Battery cell, battery device and power-consuming device

Abstract

Battery cell comprising an electrode arrangement, wherein the electrode arrangement comprises a positive electrode sheet, a separator and a negative electrode sheet stacked in the thickness direction of the battery cell; where the positive electrode sheet, a positive electrode tab, a positive electrode current collection section and comprising a positive electrode film layer arranged on at least one surface of the positive electrode current collection section along the thickness direction and containing a positive electrode active material, wherein the positive electrode tab is arranged on at least one side of the positive electrode current collection section; the negative electrode sheet, a negative electrode tab, a negative electrode current collection section and comprising a negative electrode film layer arranged on at least one surface of the negative electrode current collection section along the thickness direction and containing a negative electrode active material, wherein the negative electrode tab is arranged on at least one side of the negative electrode current collection section, wherein the ratio of the dimension of the positive electrode film layer along the longitudinal direction of the battery cell to the dimension of the positive electrode film layer along the width direction of the battery cell is 4 to 20, wherein the dimension of the positive electrode film layer along the longitudinal direction is 600 mm to 1200 mm; The one-sided coating weight of the negative electrode film layer is 74 mg / 1540.25 mm². 2 up to 156 mg / 1540.25 mm 2 amounts.

Description

Technical field

[0001] The present application relates to a battery cell, a battery device and a power-consuming device. State of the art

[0002] Battery cells are characterized by high capacity, long lifespan, and other properties, and are therefore widely used in electronic devices such as mobile phones, laptops, e-bikes, electric vehicles, electric aircraft, electric boats, electric toy cars, electric toy ships, electric toy airplanes, and power tools. As significant advancements have been made in battery technology, the demands on battery performance have also increased. However, current battery cells cannot simultaneously improve energy density and fast-charging capabilities. Disclosure of the invention

[0003] The present application provides a battery cell, a battery device and a power-consuming device that can improve the operational reliability and cycle performance of the battery cell.

[0004] In a first aspect, the present application relates to a battery cell, wherein the battery cell comprises an electrode arrangement, the electrode arrangement comprising a positive electrode sheet, a separator, and a negative electrode sheet, each arranged stacked along the thickness direction of the battery cell, wherein the positive electrode sheet comprises a positive electrode tab, a positive electrode current collection section, and a positive electrode film layer arranged on at least one surface of the positive electrode current collection section along the thickness direction and containing a positive electrode active material, wherein the positive electrode tab is arranged on at least one side of the positive electrode current collection section, and wherein the negative electrode sheet comprises a negative electrode tab, a negative electrode current collection section, and a negative electrode film layer.which is arranged on at least one surface of the negative electrode current collection section along the thickness direction and contains a negative electrode active material, wherein the negative electrode tab is arranged on at least one side of the negative electrode current collection section, wherein the ratio of the length to the width of the positive electrode film layer is 4 to 20, wherein the length of the positive electrode film layer is 600 mm to 1200 mm, and wherein the one-sided coating weight of the negative electrode film layer is 74 mg / 1540.25 mm. 2 up to 156 mg / 1540.25 mm 2 The dimension of the positive electrode film layer along the longitudinal direction is the length of the positive electrode film layer, while the dimension along the lateral direction is the width of the positive electrode film layer.

[0005] Therefore, if the embodiments of the present application meet the above requirements, the length-to-width ratio of the positive electrode film layer is within the above-mentioned range, and the one-sided coating weight of the negative electrode film layer is within the above-mentioned range, the current distribution in the positive electrode current collection section and in the negative electrode current collection section is relatively uniform, and the uniformly deintercalated lithium can be uniformly intercalated into the negative electrode sheet. The negative electrode sheet does not tend to lithium plating, which can improve the fast-charging performance of the battery cell and increase the energy density.

[0006] In some embodiments, the width of the positive electrode film layer is 60 mm to 150 mm. The relatively short width of the positive electrode film layer reduces the electron transport path in the lateral direction and improves the homogeneity of the current in that direction.

[0007] In some embodiments, the positive electrode tab is arranged on both sides of the positive electrode current collector section along the longitudinal direction of the electrode assembly. By arranging the positive electrode tab on both sides of the positive electrode current collector section along the longitudinal direction, the current is evenly distributed along the length of the positive electrode current collector section by the positive electrode tab on both sides. This results in a shorter electron transport path, a more uniform current distribution, and a uniform delithization state at each point of the positive electrode sheet, thus improving the charging performance of the battery cell.

[0008] In some embodiments, one or more positive electrode tabs are located on the same side of the positive electrode current collector section, each positive electrode tab comprising a first end face connected to the positive electrode current collector section, wherein the dimension of the first end face along the width direction is W1, the sum of the dimensions of all first end faces on the same side of the positive electrode current collector section along the width direction is n*W1, and the dimension of the positive electrode current collector section along the width direction is W2, where n*W1 / W2 is greater than or equal to 1 / 3, where n represents the number of all positive electrode tabs on the same side of the positive electrode current collector section. Optionally, n*W1 / W2 is greater than or equal to 2 / 3, where n represents the number of all positive electrode tabs on the same side of the positive electrode current collector section.

[0009] If n*W1 / W2 is in the above range, the current passage area of ​​the positive electrode tabs is relatively large, which has a positive effect on improving the fast charging performance of the battery cell.

[0010] In some embodiments, the negative electrode tab is arranged on both sides of the negative electrode current collector section along the longitudinal direction of the electrode assembly. By arranging the negative electrode tab on both sides of the negative electrode current collector section along the longitudinal direction, the current is evenly distributed along the length of the negative electrode current collector section by the negative electrode tab on both sides. This results in a shorter electron transport path and a more uniform current distribution, and the lithiation state of each point on the negative electrode sheet is uniform, thus improving the charging performance of the battery cell.

[0011] In some embodiments, one or more negative electrode tabs are located on the same side of the negative electrode current collector section, each negative electrode tab comprising a second end face connected to the negative electrode current collector section, wherein the dimension of the second end face along the width direction is W3, the sum of the dimensions of all second end faces on the same side of the negative electrode current collector section along the width direction is m*W3, and the dimension of the negative electrode current collector section along the width direction is W4, where m*W3 / W4 is greater than or equal to 1 / 3, where m represents the number of all negative electrode tabs on the same side of the negative electrode current collector section. Optionally, m*W3 / W4 is greater than or equal to 2 / 3, where m represents the number of all negative electrode tabs on the same side of the negative electrode current collector section.

[0012] If m*W3 / W4 is in the above range, the current passage area of ​​the negative electrode tabs is therefore relatively large, which has a positive effect on improving the fast charging performance of the battery cell.

[0013] In some embodiments, the positive electrode tab is arranged on at least one side of the positive electrode current collection section along the width direction. The shorter electron transport path within the positive electrode current collection section, in conjunction with a more uniform current distribution, leads to a uniform delithiation state across the entire positive electrode sheet, thus improving the charging performance of the battery cell.

[0014] In some embodiments, one or more positive electrode tabs are located on the same side of the positive electrode current collecting section, each positive electrode tab comprising a third end face connected to the positive electrode current collecting section, the dimension of the third end face being along the longitudinal direction L 10 is the sum of the dimensions of all third end faces on the same side of the positive electrode current collection section along the longitudinal direction s*L 10 is, and the dimension of the positive electrode current collection section along the longitudinal direction L1 is, where s*L 10 / L1 is greater than or equal to 1 / 3, where s represents the number of all positive electrode tabs on the same side of the positive electrode current collector section.

[0015] Therefore, the current passage area of ​​the positive electrode tabs is relatively large, which has a positive effect on improving the fast charging performance of the battery cell.

[0016] In some embodiments, the negative electrode tab is arranged on at least one side of the negative electrode current collection section along the width direction. The shorter electron transport path within the negative electrode current collection section, in conjunction with a more uniform current distribution, leads to a uniform delithiation state across the entire negative electrode sheet, thus improving the charging performance of the battery cell.

[0017] In some embodiments, one or more negative electrode tabs are located on the same side of the negative electrode current collection section, each negative electrode tab comprising a fourth end face connected to the negative electrode current collection section, the dimension of the fourth end face being along the longitudinal direction L 20 is the sum of the dimensions of all fourth end faces on the same side of the negative electrode current collection section along the longitudinal direction p*L 20 is, and the dimension of the negative electrode current collection section along the longitudinal direction L2 is, where p*L 20 / L2 is greater than or equal to 1 / 3, where p represents the number of all negative electrode tabs on the same side of the negative electrode current collector section.

[0018] Therefore, the current passage area of ​​the negative electrode tabs is relatively large, which has a positive effect on improving the fast charging performance of the battery cell.

[0019] In some embodiments, the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer along the longitudinal direction, with the difference between the dimensions of the negative electrode film layer and the positive electrode film layer being OH1, and OH1 being 0.5 mm to 3.0 mm. The larger dimension of the negative electrode film layer reduces the risk of lithium plating.

[0020] In some embodiments, the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer along the width direction, with the difference between the dimensions of the negative electrode film layer and the positive electrode film layer being OH2, and OH2 being 0.5 mm to 3.0 mm. The larger dimension of the negative electrode film layer reduces the risk of lithium plating.

[0021] In some embodiments, the positive electrode tab is arranged on two sides of the positive electrode current collector section along the longitudinal direction, and the negative electrode tab is arranged on at least one side of the negative electrode current collector section along the longitudinal direction. Along the longitudinal direction of the battery cell, the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer, wherein the difference between the dimension of the negative electrode film layer and the dimension of the positive electrode film layer is OH1; along the transverse direction of the battery cell, the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer, wherein the difference between the dimension of the negative electrode film layer and the dimension of the positive electrode film layer is OH2, where OR1 is greater than OH2.

[0022] By making OH1 larger than OH2 in the embodiments of the present application, the ability of the negative electrode film layer to absorb lithium ions in the longitudinal direction is enhanced; in particular, the ability of the negative electrode film layer to absorb lithium ions near the negative electrode tab can be improved, the risk of lithium plating can be reduced, and the operational reliability of the battery cell can be improved.

[0023] In some embodiments, the battery cell also includes a positive electrode terminal, wherein the positive electrode terminal is electrically connected to the positive electrode tab.

[0024] In some embodiments, the positive electrode terminal is directly welded to the positive electrode tab. Directly welding the positive electrode terminal to the positive electrode tab reduces the resistance at the connection, which has a positive effect on reducing the overall internal resistance of the battery cell.

[0025] In some embodiments, the battery cell further comprises a positive electrode terminal, wherein the positive electrode terminal is connected to the positive electrode tab, wherein one or at least two positive electrode terminals are provided, optionally including at least two positive electrode terminals. The at least two positive electrode terminals increase the overall current-carrying capacity of the positive electrode terminals.

[0026] In some embodiments, the number of positive electrode terminals on the same side of the positive electrode current collector section is at least two. The at least two positive electrode terminals increase the overall current-carrying capacity of the positive electrode terminals.

[0027] In some embodiments, the current-carrying area of ​​a single positive electrode terminal is 200 mm². 2 up to 800 mm 2 If the current-carrying area of ​​the positive electrode terminals meets the above condition, the current-carrying capability is relatively excellent, which favors fast charging.

[0028] In some embodiments, the battery cell also includes a negative electrode terminal which is electrically connected to the negative electrode tab.

[0029] In some embodiments, the battery cell further comprises a negative electrode terminal, wherein the negative electrode terminal is connected to the negative electrode tab, wherein one or at least two negative electrode terminals are provided, optionally including at least two negative electrode terminals. The at least two negative electrode terminals can increase the overall current-carrying capacity of the negative electrode terminals.

[0030] In some embodiments, the negative electrode terminal is directly welded to the negative electrode tab. Directly welding the negative electrode terminal to the negative electrode tab reduces the resistance at the connection, which has a positive effect on reducing the overall internal resistance of the battery cell.

[0031] In some embodiments, the number of negative electrode terminals on the same side of the negative electrode current collector section is at least two. The at least two negative electrode terminals increase the overall current-carrying capacity of the negative electrode terminals.

[0032] In some embodiments, the current-carrying area of ​​a single negative electrode terminal is 200 mm². 2 up to 800 mm 2 If the current-carrying area of ​​the negative electrode terminals meets the above condition, the current-carrying capability is relatively excellent, which favors fast charging.

[0033] In some embodiments, the battery cell comprises a housing body, which accommodates the electrode array and the electrolyte solution, and whose thickness is 0.1 mm to 0.5 mm, optionally 0.2 mm to 0.35 mm. The housing body is thin and takes up less space, which further increases the energy density of the battery cell.

[0034] In some embodiments, the compaction density of the positive electrode film layer is 2.50 g / cm³. 3 up to 2.80 g / cm³ 3 , optional 2.55 g / cm² 3 up to 2.70 g / cm³ 3, when the battery cell is at 100% charge. If the packing density of the positive electrode film layer is within the aforementioned range, this is advantageous for increasing the energy density of the battery cell; and because the positive electrode active material in the positive electrode film layer is relatively densely packed, and the contact resistance between the particles is low, the resistance of the electrode sheet can be further reduced, thereby decreasing heat generation.

[0035] In some embodiments, the one-sided coating weight of the positive electrode film layer is 160 mg / 1540.25 mm². 2 up to 340 mg / 1540.25 mm 2If the one-sided coating weight of the positive electrode film layer is within the range mentioned above, the amount of heat generated per unit area of ​​the positive electrode sheet is not too large, so that the energy density of the battery cell can be increased at the same time.

[0036] In some embodiments, the powder resistance of the positive electrode active material ranges from 1 Ω·cm to 27.5 Ω·cm. The powder resistance of the positive electrode active material is relatively low, resulting in a relatively low resistance of the positive electrode sheet and thus reduced heat generation from the battery cell.

[0037] In some embodiments, the powder compaction density of the positive electrode active material at 30000 N is 2.46 g / cm³. 3 up to 2.8 g / cm³ 3If the powder compaction density of the positive electrode active material at 30000 N is within the range mentioned above, the energy density of the battery cell can be increased, and because the positive electrode active material can be stacked more densely in the positive electrode film layer, the contact resistance between the particles is lower, which can further reduce the resistance of the electrode sheet and thus decrease heat generation.

[0038] In some embodiments, the charge capacity per gram of positive electrode active material at a rate of 0.1 C is 150 mAh / g to 170 mAh / g. If the charge capacity per gram of positive electrode active material at a rate of 0.1 C is within the above-mentioned range, the energy density of the battery cell is relatively high.

[0039] In some embodiments, the lithium-containing phosphate with an olivine structure comprises phosphate particles and a coating layer, wherein the coating layer coats the phosphate particles and contains one or more of C, Fe, Ti, Zr, Hf, Ge, and Sn. The surface coating of the phosphate particles with the coating layer can improve the conductivity of the lithium-containing phosphate with an olivine structure, reduce the powder resistance of the material, and increase the migration rate of the lithium ions, thereby reducing the amount of heat generated by the battery cell.

[0040] In some embodiments, the phosphate particles comprise a compound with the general formula of Li x1 A y1 Me a M b P 1-c X c Y z, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3 and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5 and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5, A comprises one or more of Na, K and Mg, Me comprises one or more of Mn, Fe, Co and Ni, M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce, X comprises one or more of S, Si, Cl, B, C, and N, and Y comprises one or more of O and F. The phosphate particles exhibit excellent cycle stability, which has a positive effect on improving the cycle performance of the battery cell.

[0041] In some embodiments, the coating layer comprises a fast ion conductor with the general formula of Li 3-d Fe 2-d M2 d (PO x2 ) y2, where M2 comprises one or more of Ti, Zr, Hf, Ge and Sn, and 0 < d ≤ 1, 0 < x2 < 5, 0 < y2 < 4. By surface coating phosphate particles with the fast ion conductor, the transport rate of lithium ions during multiple deintercalations and intercalations of lithium ions at the positive electrode can be significantly increased, the ionic conductivity of the positive electrode active material improved, and thereby the capacity per gram increased and the energy density of the corresponding battery cell further increased.

[0042] In some embodiments, the graphitization degree of the positive electrode active material is 0.15 to 0.32 and optionally 0.19 to 0.26. If the graphitization degree of the positive electrode active material is within the aforementioned range, this is advantageous for improving the conductivity of the positive electrode active material, reducing the heat generation of the positive electrode sheet, and thus the amount of heat generated by the battery cell.

[0043] In some embodiments, the mass fraction of the element carbon in the lithium-containing phosphate with olivine structure is 1% to 2%, and the specific surface area of ​​the lithium-containing phosphate with olivine structure is 5 m². 2 / g up to 18 m 2 / g, optional 7.5 m 2 / g up to 14 m 2 / G.

[0044] Therefore, in the embodiments of the present application, the material in which the above-mentioned mass fraction of the element carbon is combined with the above-mentioned specific surface area promotes the effective contact between the electrolyte solution and the lithium-containing phosphate with olivine structure, which promotes the transport of lithium ions at the phase interface.

[0045] In some embodiments, the lithium-containing phosphate with an olivine structure is in granular form, and its volume distribution particle size meets the following criteria: 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm. The particle size of the lithium-containing phosphate with an olivine structure is relatively small, resulting in a short deintercalation and intercalation pathway of lithium ions in the positive electrode active material and low heat generation. Furthermore, the particle size of the aforementioned positive electrode active material is not too small, and agglomeration is practically non-existent during processing and manufacturing, thus maintaining stable performance of the positive electrode active material.

[0046] In some embodiments, the lithium-containing phosphate with an olivine structure is in granular form and comprises secondary particles, wherein the secondary particles contain several primary particles, the average particle size of which is 200 nm to 500 nm. The average particle size of the primary particles is relatively small, resulting in a short deintercalation and intercalation path of lithium ions in the positive electrode active material and a low amount of heat generation.

[0047] In some embodiments, the particle size of the smallest particle in the lithium-containing phosphate with an olivine structure is 0.1 µm to 0.4 µm. If the particle size of the smallest particle is within the aforementioned range, the particles do not agglomerate as readily during the production of the positive electrode film layer.

[0048] In some embodiments, the particle size of the largest particle in the lithium-containing phosphate with olivine structure is 15 µm to 25 µm. If the particle size of the largest particle is within the aforementioned range, the migration path of the lithium ions during the charging and discharging process is not too long, which can improve the fast charging and discharging performance of the battery cell.

[0049] In some embodiments, the ratio of the thickness of the positive electrode current collection section to the thickness of the one-sided positive electrode film layer is 0.05 to 0.3. If the ratio of the thickness of the positive electrode current collection section to the thickness of the one-sided positive electrode film layer is within the aforementioned range, the fast-charging capability and the energy density of the battery cell can be increased.

[0050] In some embodiments, the thickness of the positive electrode current collector section is 10 µm to 15 µm. If the thickness of the positive electrode current collector section is within the aforementioned range, the positive electrode current collector section exhibits relatively excellent current conductivity and enables a higher energy density of the battery cell.

[0051] In some embodiments, the positive electrode film layer also comprises a first material, wherein the first material comprises one or more of the following: ternary material, lithium phosphate, lithium dihydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, trilithium citrate, lithium nickelate, and lithium ferrite. The first material can be used as a lithium replenisher and add lithium ions to the positive electrode film layer to compensate for the irreversible lithium ion loss in the system and to increase the capacity, which in turn increases the energy density of the battery cell.

[0052] In some embodiments, the mass fraction of the lithium supplement in the positive electrode film layer is 0.5% to 5%. If the mass fraction of the lithium supplement is within the aforementioned range, it can replenish lithium ions for the positive electrode film layer, compensate for the irreversible lithium ion loss in the system, and increase the capacity and thus the energy density of the battery cell.

[0053] In some embodiments, the positive electrode sheet further comprises a conductive layer of the positive electrode, wherein the conductive layer of the positive electrode is located between the positive electrode film layer and the positive electrode current collection section. The conductive layer of the positive electrode can further improve the conductivity of the positive electrode sheet and reduce the heat generation of the positive electrode sheet, thereby reducing the amount of heat generated by the battery cell.

[0054] In some embodiments, the thickness of the conductive layer of the positive electrode is 0.5 µm to 2 µm. If the thickness of the conductive layer of the positive electrode is within the aforementioned range, the conductivity of the positive electrode sheet can be further improved and the heat generation of the positive electrode sheet reduced, thereby reducing the heat generation of the battery cell and simultaneously increasing the energy density of the battery cell.

[0055] In some embodiments, the conductive layer of the positive electrode comprises one or more positive electrode conductive elements and positive electrode binders. The positive electrode conductive element in the conductive layer of the positive electrode can improve the conductivity of the positive electrode layer, thereby improving the conductivity of the positive electrode sheet and reducing the amount of heat generated by the battery cell. The positive electrode binder in the conductive layer of the positive electrode can improve the bonding performance between the positive electrode current collector section and the positive electrode film layer, thus improving the structural stability of the positive electrode sheet.

[0056] In some embodiments, the conductive medium of the positive electrode comprises one or more of superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen carbon black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0057] In some embodiments, the binder of the positive electrode comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid and fluorine-containing acrylate resin.

[0058] In some embodiments, the powder compaction density of the negative electrode active material at 20000 N is 1.5 g / cm³. 3 up to 1.85 g / cm³ 3If the powder compaction density of the negative electrode active material at 20000 N is within the range mentioned above, the energy density of the battery cell can be increased, and because the negative electrode active material can be stacked more densely in the negative electrode film layer, the contact resistance between the particles is lower, which can further reduce the resistance of the electrode sheet and thus decrease heat generation.

[0059] In some embodiments, the charge capacity per gram of negative electrode active material at a rate of 0.1 C is greater than or equal to 350 mAh / g. If the charge capacity per gram of negative electrode active material at a rate of 0.1 C is within the aforementioned range, the energy density of the battery cell is relatively high.

[0060] In some embodiments, the negative electrode active material comprises a carbon-based material, wherein the carbon-based material includes graphite particles, the graphiteization degree of the graphite particles being between 92.0% and 94.5%. When the graphiteization degree of the graphite particles is within the aforementioned range, the graphite particles exhibit excellent conductivity, which can reduce heat generation from the negative electrode sheet and the battery cell, and improve the fast-charging performance of the battery cell.

[0061] In some embodiments, the graphite particles comprise synthetic graphite and a carbon coating layer, wherein the synthetic graphite includes secondary particles and the surface of the synthetic graphite is coated with the carbon coating layer. The carbon coating layer has more end faces and defects, thereby increasing the number of sites where lithium ions can deintercalate and intercalate. This makes the carbon coating layer more conductive, which can reduce the internal resistance of the negative electrode sheet and thus the amount of heat generated by the battery cell.

[0062] In some embodiments, the mass fraction of the carbon coating layer is 2% to 5%, based on the mass of the graphite particles. If the mass fraction of the carbon coating layer is within the aforementioned range, the internal resistance of the negative electrode sheet can be further reduced and the amount of heat generated by the battery cell can be decreased.

[0063] In some embodiments, the negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer is arranged on the surface of the negative electrode current collection section, the first negative electrode film layer comprises a carbon-based material, the second negative electrode film layer is connected to the side of the first negative electrode film layer facing away from the negative electrode current collection section, the second negative electrode film layer comprises a carbon-based material, wherein the carbon-based material in the first negative electrode film layer and the carbon-based material in the second negative electrode film layer each independently comprise graphite particles.wherein the volume-averaged particle size Dv50 of the graphite particles in the first negative electrode film layer is greater than or equal to the volume-averaged particle size Dv50 of the graphite particles in the second negative electrode film layer.

[0064] Therefore, the particle size in the first and second negative electrode film layers differs in the embodiments of the present application, which can improve the fast-charging performance of the battery cell. In particular, during fast charging, the overpotential of the second negative electrode film layer is typically higher, and the bottleneck during fast charging is mainly in the second negative electrode film layer. In the embodiments of the present application, the particle size in the second negative electrode film layer is relatively small, which can shorten the solid-phase transport path of the lithium ions, improve fast-charging performance, and enhance lithium plating on the surface of the negative electrode sheet.

[0065] In some embodiments, the carbon-based material in the first negative electrode film layer further comprises natural graphite.

[0066] In some embodiments, the bulk density of the carbon-based material in the first negative electrode film layer is less than or equal to the bulk density of the carbon-based material in the second negative electrode film layer. If the bulk density of the carbon-based material in the second negative electrode film layer is greater than the bulk density of the carbon-based material in the first negative electrode film layer, the second negative electrode film layer is more densely filled, thereby increasing the energy density of the battery cell. The first negative electrode film layer is relatively thinly filled and has more pores, which can improve the fast-charging performance of the battery cell.

[0067] In some embodiments, the bulk density of the carbon-based material in the first negative electrode film layer is 0.82 g / cm³. 3 up to 1.21 g / cm³ 3If the bulk density of the carbon-based material in the first negative electrode film layer is within a suitable range, the fast charging performance of the battery cell can be improved.

[0068] In some embodiments, the bulk density of the carbon-based material in the second negative electrode film layer is 0.90 g / cm³. 3 up to 1.25 g / cm³ 3 If the bulk density of the carbon-based material in the second negative electrode film layer is within a suitable range, the energy density of the battery cell can be increased.

[0069] In some embodiments, the volume-averaged particle size Dv50 of the graphite particles in the first negative electrode film layer is 9.5 µm to 18.5 µm. If the volume-averaged particle size Dv50 of the negative electrode active material in the first negative electrode film layer is within the aforementioned range, the fast charging performance can be improved.

[0070] In some embodiments, the volume-averaged particle size Dv50 of the graphite particles in the second negative electrode film layer is 7.8 µm to 14.3 µm. If the volume-averaged particle size Dv50 of the negative electrode active material in the second negative electrode film layer is within the aforementioned range, the tortuosity of lithium ion transport can be reduced and the fast-charging performance of the battery cell improved.

[0071] In some embodiments, the first negative electrode film layer further comprises a first lithium-containing binder and the second negative electrode film layer further comprises a second lithium-containing binder, wherein the mass fraction of the first lithium-containing binder, based on the mass of the first negative electrode film layer, is less than or equal to the mass fraction of the second lithium-containing binder, based on the mass of the second negative electrode film layer.

[0072] Therefore, in the embodiments of the present application, the mass fraction of the second lithium-containing binder in the second negative electrode film layer is relatively high, and the second lithium-containing binder provides a relatively larger number of freely moving lithium ions for the second negative electrode film layer, which can further improve the fast charging performance of the battery cell.

[0073] In some embodiments, the mass fraction of the first lithium-containing binder, relative to the mass of the first negative electrode film layer, is 0.1% to 1%. If the mass fraction of the first lithium-containing binder is within the aforementioned range, the deintercalation and intercalation rate of the lithium ions can be increased, thereby improving the fast-charging performance of the battery cell.

[0074] In some embodiments, the mass fraction of elemental lithium in the first lithium-containing binder is 3% to 10%, optionally 3% to 8%. If the mass fraction of elemental lithium is within the aforementioned range, the number of lithium ions freely moving in the negative electrode film layer can be relatively large, thereby further reducing the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increasing the deintercalation and intercalation rate of the lithium ions, and improving the fast-charging performance of the battery cell.

[0075] In some embodiments, the mass fraction of the second lithium-containing binder, relative to the mass of the second negative electrode film layer, is 0.1% to 1%. If the mass fraction of the element lithium in the second lithium-containing binder is within the aforementioned range, the deintercalation and intercalation rate of the lithium ions is increased, thereby improving the fast-charging performance of the battery cell.

[0076] In some embodiments, the mass fraction of elemental lithium in the second lithium-containing binder is 3% to 10%, optionally 3% to 8%. If the mass fraction of elemental lithium is within the aforementioned range, the number of lithium ions freely moving in the negative electrode film layer can be relatively large, thereby further reducing the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increasing the deintercalation and intercalation rate of the lithium ions, and improving the fast-charging performance of the battery cell.

[0077] In some embodiments, the first lithium-containing binder comprises a lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 30% to 50%:15% to 45%:5% to 20%:20% to 35%.

[0078] Therefore, the lithium-containing binder from the above material can provide a specific number of lithium ions for the negative electrode film layer, thus improving the fast-charging performance of the battery cell. Furthermore, it does not swell as easily during charging and discharging and exhibits a stable structure, thereby improving the cycle life of the negative electrode film layer during fast charging and discharging.

[0079] In some embodiments, the second lithium-containing binder comprises a lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 30% to 50%:15% to 45%:5% to 20%:20% to 35%.

[0080] Therefore, the lithium-containing binder from the above material can provide a specific number of lithium ions for the negative electrode film layer, thus improving the fast-charging performance of the battery cell. Furthermore, it does not swell as easily during charging and discharging and exhibits a stable structure, thereby improving the cycle life of the negative electrode film layer during fast charging and discharging.

[0081] In some embodiments, the negative electrode active material further comprises a silicon-based material, wherein the mass fraction of the element silicon in the silicon-based material is 0.3% to 10.0%, based on the mass of the negative electrode active material. The introduction of the silicon-based material can increase the capacity of the negative electrode active material and the energy density of the battery cell.

[0082] In some embodiments, the thickness of the negative electrode current collector section is 4 µm to 6 µm. If the thickness of the negative electrode current collector section is within the aforementioned range, the negative electrode current collector section exhibits relatively excellent current conductivity and enables a higher energy density of the battery cell.

[0083] In some embodiments, the negative electrode sheet further comprises a conductive layer of the negative electrode, wherein the conductive layer of the negative electrode is located between the negative electrode film layer and the negative electrode current collection section.

[0084] In some embodiments, the thickness of the conductive layer of the negative electrode is 0.5 µm to 2 µm. The conductive layer of the negative electrode can further improve the conductivity of the negative electrode sheet and reduce heat generation from the negative electrode sheet, thereby reducing the amount of heat generated by the battery cell.

[0085] In some embodiments, the conductive layer of the negative electrode comprises one or more negative electrode conductive elements and negative electrode binders. The conductive element in the negative electrode conductive layer can improve the conductivity of the negative electrode conductive layer, thereby improving the conductivity of the negative electrode sheet and reducing the amount of heat generated by the battery cell. The negative electrode binder in the conductive layer of the negative electrode can improve the bonding performance between the negative electrode current collector section and the negative electrode film layer, thereby increasing the structural stability of the negative electrode sheet.

[0086] In some embodiments, the conductive medium of the negative electrode comprises one or more of superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen carbon black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0087] In some embodiments, the binder of the negative electrode comprises one or more of styrene-butadiene rubber, water-soluble unsaturated resin SR-1B, aqueous acrylic resin, polyvinyl alcohol, sodium alginate, and carboxymethyl chitosan.

[0088] In some embodiments, the separator comprises a base film with a porous structure, wherein the porosity of the base film is between 20% and 70%. If the porosity of the separator in the embodiments of the present application is within the aforementioned range, the migration capability of the lithium ions in the separator can be improved and the internal resistance of the battery cell can be further reduced, thereby reducing heat generation.

[0089] In some embodiments, the separator comprises a base film with a porous structure, wherein the porosity of the base film is between 35% and 60%. If the porosity of the separator in the embodiments of the present application is within the aforementioned range, the migration capability of the lithium ions in the separator can be improved and the internal resistance of the battery cell can be further reduced, thereby reducing heat generation.

[0090] In some embodiments, the thickness of the base film is 6 µm to 12 µm. If the thickness of the base film is within the aforementioned range, the migration path of the lithium ions in the base film is shorter, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation.

[0091] In some embodiments, the thickness of the base film is 6 µm to 9 µm. If the thickness of the base film is within the aforementioned range, the migration path of the lithium ions in the base film is shorter, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation.

[0092] In some embodiments, the separator comprises a base film and a functional layer arranged on at least one side of the base film. The functional layer comprises a first functional layer and a second functional layer, wherein the first functional layer is located on one side of the base film and comprises first inorganic particles. The second functional layer is located on the other side of the base film and comprises composite particles, wherein the composite particles comprise second inorganic particles and several non-fluoropolymer particles. The second inorganic particles adhere to the surface of the non-fluoropolymer particles and / or are dispersed within the non-fluoropolymer particles. The first and second functional layers exhibit good heat resistance and can increase the heat resistance of the separator.

[0093] In some embodiments, the non-fluoropolymer particles comprise an acrylate copolymer. This acrylate copolymer is characterized by excellent bonding performance and high bond stability with the base film.

[0094] In some embodiments, the first inorganic particles comprise one or more of silicon dioxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium dioxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. The aforementioned first inorganic particles can increase the heat resistance of the first functional layer.

[0095] In some embodiments, the second inorganic particles comprise one or more of silicon dioxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium dioxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These second inorganic particles can increase the heat resistance of the first functional layer.

[0096] In some embodiments, the average particle size of the second inorganic particles is 5 nm to 100 nm. Having the average particle size of the second inorganic particles within the aforementioned range is advantageous for increasing the heat resistance and bulk modulus of the composite particles.

[0097] In some embodiments, the carboxylic acid ester solvent comprises a chain-like carboxylic acid ester solvent, wherein the mass fraction of the chain-like carboxylic acid ester solvent in the organic solvent is greater than or equal to 5% and less than or equal to 75%, optionally greater than or equal to 10% and less than or equal to 75%, or optionally from 30% to 75%. When the mass fraction of the chain-like carboxylic acid ester solvent is within the aforementioned range, the viscosity of the electrolyte solution system is relatively low, which has a positive effect on the migration of lithium ions.

[0098] In some embodiments, the chain-like carboxylic acid ester solvent comprises a compound represented by formula I, where in Formula I, R1 comprises a hydrogen atom, a halogen atom, a C1 to C5 alkyl group, or a halogenated C1 to C5 alkyl group, and R2 comprises a C1 to C5 alkyl group or a halogenated C1 to C5 alkyl group. Therefore, in the embodiments of the present application, the aforementioned chain-like carboxylic acid ester solvent exhibits high conductivity, which has a positive effect on the fast-charging capability of the battery cell.

[0099] In some embodiments, R1 comprises a hydrogen atom, a halogen atom, a C1 to C3 alkyl group, or a halogenated C1 to C3 alkyl group.

[0100] In some embodiments, R2 comprises a C1 to C3 alkyl group or a halogenated C1 to C3 alkyl group.

[0101] In some embodiments, the chain-like carboxylic acid ester solvent comprises one or more of the compounds represented by Formula I-1 to Formula I-8,

[0102] In some embodiments, the organic solvent further comprises carbonate solvents, wherein the carbonate solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The aforementioned carbonate solvent and chain-like carboxylic acid ester solvents are used together to improve the conductivity of the electrolyte solution, which has a positive effect on the migration of lithium ions.

[0103] In some embodiments, the carbonate solvent comprises one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0104] In some embodiments, the mass fraction of the carbonate solvent in the organic solvent is 25% to 95%, optionally 25% to 70%. The carbonate solvent with the aforementioned mass fraction can further improve the conductivity of the electrolyte solution, which has a positive effect on the migration of lithium ions.

[0105] In some embodiments, the electrolyte solution further comprises an additive, wherein the additive includes one or more carbonate additives, sulfur-containing additives, and lithium salt additives. The aforementioned additive can improve the performance of the interfacial films on the positive electrode side and / or the negative electrode side, which has a positive effect on improving the fast-charging performance of the battery cell and its cycle life.

[0106] In some embodiments, the carbonate additive comprises one or more of vinylene carbonate VC and fluoroethylene carbonate FEC.

[0107] In some embodiments, the sulfur-containing additive comprises one or more of ethylene sulfate DTD, bis(ethylene sulfate) 2-DTD, butylene sulfite BS, 1,3-propanesultone PS, ethylene sulfite ES and methylenemethanedisulfonate MMDS.

[0108] In some embodiments, the lithium salt additive comprises one or more of lithium difluorophosphate LiPO2F2, lithium difluoro(oxalato)borate LiDFOB, lithium tetrafluoroborate LiBF4, and lithium bis(oxalato)borate LiBOB.

[0109] In some embodiments, the mass fraction of the additive in the electrolyte solution is 1% to 10% and optionally 2% to 8%. The additive with the aforementioned mass fraction can effectively improve the performance of the interfacial films on the positive electrode side and / or the negative electrode side, which has a positive effect on improving the fast-charging performance of the battery cell and the cycle life.

[0110] In some embodiments, the electrolyte solution further comprises a lithium salt, wherein the lithium salt includes one or more fluorinated sulfonylimide salts and lithium hexafluorophosphate (LiPF6). The aforementioned lithium salt is readily dissociated, which promotes the rapid migration of lithium ions. Furthermore, the electrolyte solution system is relatively stable and does not decompose easily, which can improve the cycle life of the battery cell.

[0111] In some embodiments, the fluorine-containing sulfonylimide salt comprises one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0112] In some embodiments, the lithium salt comprises lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. The molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L.

[0113] In some embodiments, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate LiPF6 is 0.2 to 1.0.

[0114] In some embodiments, the charging time for the battery cell from 20% to 80% charge is 6 to 15 minutes. The charging speed of the battery cell is faster, which further improves the fast-charging capability.

[0115] In a second aspect, the present application proposes a battery device comprising several battery cells according to any embodiment of the first aspect of the present application.

[0116] In some embodiments, the charging time for the battery device from 20% to 80% charge is 6 to 15 minutes. The faster charging speed of the battery device primarily contributes to improved fast-charging capability.

[0117] In a third aspect, the present application proposes a power-consuming device comprising a battery device according to any embodiment of the second aspect of the present application. Brief description of the drawings

[0118] To better illustrate the technical solutions in the embodiments of the present application, a brief description of the drawings required in these embodiments is given below. Of course, the drawings described below represent only some embodiments of the present application, and other drawings can be created by a person skilled in the art based on these drawings without any creative effort. Fig. Figure 1 is a schematic representation of the structure of a battery cell according to some embodiments of the present application; Fig. Figure 2 is a schematic exploded view of the battery cell according to some embodiments of the present application; Fig. Figure 3 is a schematic sectional view of an electrode arrangement of a battery cell according to some embodiments of the present application; Fig.Figure 4 is a schematic representation of the structure of a positive electrode sheet of a battery cell according to some embodiments of the present application; Fig. Figure 5 is a schematic representation of the structure of a negative electrode sheet of a battery cell according to some embodiments of the present application; Fig. Figure 6 is a schematic representation of the structure of a positive electrode sheet of a battery cell according to some further embodiments of the present application; Fig. Figure 7 is a schematic representation of the structure of a negative electrode sheet of a battery cell according to some further embodiments of the present application; Fig. Figure 8 is a schematic representation of the structure of an electrode arrangement of the battery cell according to some embodiments of the present application; Fig.Figure 9 is a schematic representation of the structure of a battery cell according to some further embodiments of the present application; Fig. Figure 10 is a schematic representation of the structure of a battery module according to some embodiments of the present application; Fig. Figure 11 is a schematic representation of the structure of a battery pack according to some embodiments of the present application; Fig. Figure 12 is a schematic representation of the structure of a power-consuming device according to some embodiments of the present application.

[0119] The drawings are not necessarily to scale. Reference symbol list:

[0120] X. Thickness direction; Y. Width direction; Z. Length direction; 1. Power-consuming device; 2. Battery pack; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Receiving compartment; 6. Battery module; 7. Battery cell; 10. Electrode arrangement; 11. Positive electrode sheet; 111. Positive electrode tab; 1111. First end face; 1112. Third end face; 112. Positive electrode current collection section; 113. Positive electrode film layer; 12. Negative electrode sheet; 121. Negative electrode tab; 1211. Second end face; 1212. Fourth end face; 122. Negative electrode current collection section; 123. Negative electrode film layer; 13. Separator; 20. Housing; 21. Housing body; 211. First housing section; 212. Second housing section; 22. End cap; 31. Positive electrode connection; 32. Negative electrode connection. Detailed descriptions

[0121] The following section describes in detail embodiments of a battery cell, a battery device, and a power-consuming device specifically disclosed in the present application, possibly with reference to the drawings. However, an unnecessarily detailed description can be omitted. For example, a detailed description of known facts and a repeated description of essentially the same structure can be avoided. This is to prevent the following description from becoming unnecessarily lengthy, thus facilitating understanding by those skilled in the art. Furthermore, the drawings and the following description serve to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0122] The “range” disclosed in the present application is defined in terms of a lower bound and an upper bound. A given range is defined by selecting a lower bound and an upper bound. The selected lower bound and upper bound define the limits of the specific range. The ranges thus defined may or may not include the end values ​​and may be specified in any combination; that is, any lower bound can be combined with any upper bound to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, then ranges of 60 to 110 and 80 to 120 are also conceivable. Furthermore, if minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are listed, then all of the following ranges are conceivable: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.In the present application, unless otherwise specified, a range of numbers "a to b" represents an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the range "0 to 5" means that all real numbers between "0 to 5" are listed therein, and "0 to 5" is simply an abbreviation for these number combinations. Furthermore, if a particular parameter is specified as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0123] Unless otherwise stated, all embodiments and optional embodiments of the present application may be combined to form a new technical solution.

[0124] Unless otherwise stated, all technical features and optional technical features of the present application may be combined to form a new technical solution.

[0125] Unless otherwise stated, all steps of the present application may be carried out sequentially or in any order, but preferably sequentially. For example, a method comprising steps (a) and (b) means that the method may include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially. Similarly, if it is mentioned that the method may further include step (c), this means that step (c) may be added in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0126] With the development of the battery sector, the demands on battery energy density and fast charging are gradually increasing. However, studies have shown that increasing battery energy density can lead to increased transport resistance of active ions such as lithium ions, making fast charging of the battery cell impossible. Therefore, it is not possible to improve both battery energy density and fast charging capability simultaneously.

[0127] In view of the aforementioned problems, the embodiments of the present application design the battery cell and improve the structure, size of the electrode sheet and the coating weight of the film layer, so that the energy density and fast-charging capability of the battery cell can be improved simultaneously. Battery cell

[0128] In a first aspect, the embodiments of the present application propose a battery cell.

[0129] As in the Fig.As shown in Figures 1 to 5, the battery cell 7 comprises an electrode arrangement 10 and an electrolyte solution, wherein the electrode arrangement 10 comprises a positive electrode sheet 11, a separator 13 and a negative electrode sheet 12, each stacked along the thickness direction X of the battery cell 7, wherein the positive electrode sheet 11 comprises a positive electrode tab 111, a positive electrode current collector section 112 and a positive electrode film layer 113, which is arranged on at least one surface of the positive electrode current collector section 112 along the thickness direction X and contains a positive electrode active material, wherein the positive electrode tab 111 is arranged on at least one side of the positive electrode current collector section 112, wherein the negative electrode sheet 12 comprises a negative electrode tab 121, a negative electrode current collector section 122 and a negative electrode film layer 123.which is arranged on at least one surface of the negative electrode current collection section 122 along the thickness direction X and contains a negative electrode active material, wherein the negative electrode tab 121 is arranged on at least one side of the negative electrode current collection section 122, wherein the ratio of the length to the width of the positive electrode film layer 113 is 4 to 20, wherein the length of the positive electrode film layer 113 is 600 mm to 1200 mm, wherein the one-sided coating weight of the negative electrode film layer 123 is 74 mg / 1540.25 mm, 2 up to 156 mg / 1540.25 mm 2 amounts.

[0130] The electrode arrangement 10 of the embodiments of the present application is a stacked electrode arrangement 10, and the positive electrode sheet 11, the separator 13, and the negative electrode sheet 12 are formed into the electrode arrangement 10 by a stacking process. The thickness direction X of the electrode arrangement 10, the thickness direction of the positive electrode sheet 11, and the thickness direction of the negative electrode sheet 12 are parallel; the width direction of the electrode arrangement 10, the width direction of the positive electrode sheet 11, and the width direction of the negative electrode sheet 12 are parallel; and the length direction of the electrode arrangement 10, the length direction of the positive electrode sheet 11, and the length direction of the negative electrode sheet 12 are parallel.The thickness direction X of the electrode arrangement 10, the width direction of the electrode arrangement 10 and the length direction of the electrode arrangement 10 are pairwise perpendicular to each other, wherein the width direction of the electrode arrangement 10 is denoted by Y and the length direction of the electrode arrangement 10 is denoted by Z.

[0131] In the embodiments of the present application, the dimension of the positive electrode sheet 11 along the thickness direction of the battery cell 7 can be understood as the thickness of the positive electrode sheet 11. The dimension of the positive electrode sheet 11 along the longitudinal direction of the battery cell 7 can be understood as the length of the positive electrode sheet 11. The dimension of the positive electrode sheet 11 along the width direction of the battery cell 7 can be understood as the width of the positive electrode sheet 11. Fig.4. The length of the positive electrode current collection section 112 is equal to the length of the positive electrode film layer 113, where both the length of the positive electrode film layer 113 and the length of the positive electrode current collection section 112 can be denoted by L1. In Fig. 4 the width of the positive electrode current collection section 112 is equal to the width of the positive electrode film layer 113, where both the width of the positive electrode film layer 113 and the width of the positive electrode current collection section 112 can be denoted by W2.

[0132] In the embodiments of the present application, the dimension of the negative electrode sheet 12 along the thickness direction of the battery cell 7 can be understood as the thickness of the negative electrode sheet 12. The dimension of the negative electrode sheet 12 along the longitudinal direction of the battery cell 7 can be understood as the length of the negative electrode sheet 12. The dimension of the negative electrode sheet 12 along the width direction of the battery cell 7 can be understood as the width of the negative electrode sheet 12. Fig. 5. The length of the negative electrode current collection section 122 is equal to the length of the negative electrode film layer 123, where the length of the negative electrode film layer 123 can be denoted by L2 and the length of the negative electrode current collection section 122 can also be denoted by L2. In Fig.5 the width of the negative electrode current collection section 122 is equal to the width of the negative electrode film layer 123, where both the width of the negative electrode film layer 123 and the width of the negative electrode current collection section 122 can be designated by W4.

[0133] Both the positive electrode sheet 11 and the negative electrode sheet 12 influence the energy density and fast-charging performance of the battery cell 7. Improving the positive electrode sheet 11 and the negative electrode sheet 12 improves the energy density and fast-charging performance of the battery cell 7. Specifically:

[0134] If the one-sided coating weight of the negative electrode film layer 123 is less than 74 mg / 1540.25 mm 2 The energy density of battery cell 7 is low; if the one-sided coating weight of the negative electrode film layer 123 is greater than 156 mg / 1540.25 mm² 2The migration path of active ions such as lithium ions in the negative electrode film layer 123 is long, although the energy density of the battery cell 7 is improved, which is not conducive to the rapid charging and discharging of the battery cell 7; and the one-sided coating weight of the negative electrode film layer 123 in the embodiments of the present application is 74 mg / 1540.25 mm². 2 up to 156 mg / 1540.25 mm 2 determined, thereby enabling a favorable balance between fast charging performance and energy density;

[0135] If the length-to-width ratio of the positive electrode film layer 113 is less than 4, the coating weight of the positive electrode film layer 113 is relatively low and the energy density of the battery cell 7 is relatively low. By increasing the length-to-width ratio of the positive electrode film layer 113 and by setting the length-to-width ratio of the positive electrode film layer 113 to less than or equal to 20, the coating weight of the positive electrode film layer 113 is advantageously increased and the energy density of the battery cell 7 is improved.However, with an increasing length-to-width ratio of the positive electrode film layer 113, the size difference between the length and width of the positive electrode film layer 113 also increases, which can easily lead to an uneven current distribution in the positive electrode sheet 11. This, in turn, leads to an uneven state of charge of the positive electrode film layer 113 during charging. The delithiation rate varies in different areas of the positive electrode film layer 113. The lithium deintercalated from the positive electrode film layer 113 is subsequently intercalated into the negative electrode sheet 12, resulting in an uneven lithiation rate in the negative electrode sheet 12. This easily leads to lithium plating in the negative electrode sheet 12.

[0136] If the length-to-width ratio of the positive electrode film layer 113 is less than or equal to 20, a positive electrode tab 111 is arranged on at least one side of the positive electrode current collector section 112. Optionally, positive electrode tabs 111 are arranged on both sides. The positive electrode tabs 111 can share the current among themselves, shorten the electron transport path in the positive electrode current collector section 112, and promote a more uniform current distribution. During the charging process, this enables uniform delithization of the positive electrode active material across the entire positive electrode sheet 11.Since the negative electrode current collector section 122 has a negative electrode tab 121 on at least one side, and optionally negative electrode tabs 121 on both sides, the negative electrode tabs 121 can share the current, shorten the electron transport path in the negative electrode current collector section 122, and promote a more uniform current distribution. The uniformly deintercalated lithium can be uniformly intercalated into the negative electrode sheet 12, thus preventing the negative electrode sheet 12 from becoming lithium-plated. Furthermore, the one-sided coating weight of the negative electrode film layer 123 is 74 mg / 1540.25 mm². 2 up to 156 mg / 1540.25 mm 2 This results in a relatively short migration path for lithium ions in the negative electrode film layer 123, thereby improving the fast charging performance of the battery cell 7.

[0137] Therefore, by coordinated adjustment of the length-to-width ratio of the positive electrode film layer 113 and the one-sided coating weight of the negative electrode film layer 123, the energy density and fast-charging performance of the battery cell 7 can be improved simultaneously.

[0138] In the embodiments of the present application, the ratio of the length to the width of the positive electrode film layer is 113 4 to 20, for example 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20 or lies in a range consisting of any two of the above values.

[0139] In the embodiments of the present application, the length of the positive electrode film layer 113 is 600 mm to 1200 mm, and by way of example, the length of the positive electrode film layer 113 can be 600 mm, 650 mm, 700 mm, 750 mm, 800 mm, 850 mm, 900 mm, 950 mm, 1000 mm, 1050 mm, 1100 mm, 1150 mm, 1200 mm, or lie in a range consisting of any two of the above values. The length of the positive electrode film layer 113 is relatively long, which has a positive effect on increasing the coating weight of the positive electrode film layer 113 and improving the energy density of the battery cell 7.

[0140] In some embodiments, the width of the positive electrode film layer 113 is 60 mm to 150 mm, and by way of example, the width of the positive electrode film layer 113 can be 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, 150 mm, or lie in a range consisting of any two of the above values. The width of the positive electrode film layer 113 is relatively short, which shortens the transport path of the electrons in the lateral direction Y and can improve the homogeneity of the current in the lateral direction Y.

[0141] The positive electrode tab 111 is arranged on at least one side of the positive electrode current collecting section 112.

[0142] In some embodiments, the positive electrode tab 111 can be arranged on at least one side of the positive electrode current collection section 112 along the longitudinal direction Z. Optionally, the positive electrode tabs 111 are arranged on both sides of the positive electrode current collection section 112 along the longitudinal direction Z. Since the length of the positive electrode current collection section 112 is greater than its width, the current path in the longitudinal direction Z is longer, and the current distribution in the longitudinal direction Z is uneven. By arranging the positive electrode tabs 111 on both sides of the positive electrode current collection section 112 along the longitudinal direction Z, the current in the longitudinal direction Z of the positive electrode current collection section 112 is distributed evenly by the positive electrode tabs 111 on both sides.This results in a shorter electron transport path and a more uniform current distribution; the delithiation state of each point on the positive electrode sheet 11 is uniform, thus improving the charging performance of the battery cell 7. Fig. Figure 4 shows that the positive electrode tabs 111 are arranged on both sides of the positive electrode current collector section 112 along the longitudinal direction Z. The positive electrode tabs 111 are arranged on both sides, allowing them to share the current, shorten the electron transport path in the positive electrode current collector section 112, and promote a more uniform current distribution. During charging, this enables uniform delithization of the positive electrode active material across the entire positive electrode sheet 11.

[0143] If the positive electrode tab 111 is arranged on at least one side of the positive electrode current collector section 112 along the longitudinal direction Z, the number of positive electrode tabs 111 on the same side of the positive electrode current collector section 112 can be at least one, for example, or at least two. If the number of positive electrode tabs 111 on the same side of the positive electrode current collector section 112 is at least two, the at least two positive electrode tabs 111 can increase the current passage area and distribute the current evenly, thereby improving the current uniformity in the positive electrode sheet 11, which has a positive effect on further improving the fast-charging performance of the battery cell 7.

[0144] In some embodiments, one or more positive electrode tabs 111 are located on the same side of the positive electrode current collector section 112, and, for example, all positive electrode tabs 111 are located on the same side of the positive electrode current collector section 112 along the longitudinal direction Z, or alternatively, all positive electrode tabs 111 are arranged on both sides of the positive electrode current collector section 112 along the longitudinal direction Z. The positive electrode tab 111 comprises a first end face 1111 which is connected to the positive electrode current collector section 112, wherein the dimension of the first end face 1111 along the lateral direction Y is W1.The sum of the dimensions of all first end faces 1111 located on the same side of the positive electrode current collector section 112 is n*W1. The width of the positive electrode current collector section 112 is W2, where n*W1 / W2 is greater than or equal to 1 / 3 and less than or equal to 1, optionally greater than or equal to 2 / 3 and less than 1, where n represents the number of all positive electrode tabs 111 on the same side of the positive electrode current collector section 112, and n is greater than or equal to 1. For example, if the number of all positive electrode tabs 111 on the same side of the positive electrode current collector section 112 is 1, then n is 1; if the number of all positive electrode tabs 111 on the same side of the positive electrode current collector section 112 is 2, then n is 2.

[0145] For example, n*W1 / W2 is 1 / 3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.85, 0.9 or lies in a range consisting of any two of the above values.

[0146] If n*W1 / W2 is in the above range, the current passage area of ​​the positive electrode tabs 111 is relatively large, which has a positive effect on improving the fast charging performance of the battery cell 7.

[0147] The negative electrode tab 121 is arranged on at least one side of the negative electrode current collection section 122.

[0148] In some embodiments, the negative electrode tab 121 can be arranged on at least one side of the negative electrode current collection section 122 along the longitudinal direction Z. Optionally, the negative electrode tabs 121 are arranged on both sides of the negative electrode current collection section 122 along the longitudinal direction Z. Since the length of the negative electrode current collection section 122 is greater than its width, the current path in the longitudinal direction Z is longer, and the current distribution in the longitudinal direction Z is uneven. By arranging the negative electrode tabs 121 on both sides of the negative electrode current collection section 122 along the longitudinal direction Z, the current in the longitudinal direction Z of the negative electrode current collection section 122 is distributed evenly by the negative electrode tabs 121 on both sides.This results in a shorter electron transport path and a more uniform current distribution; the lithiation state of each point on the negative electrode sheet 12 is uniform, thus improving the charging performance of the battery cell 7. Fig. Figure 5 shows that the negative electrode tabs 121 are arranged on both sides of the negative electrode current collecting section 122 along the longitudinal direction Z.

[0149] If the negative electrode tab 121 is arranged on at least one side of the negative electrode current collector section 122 along the longitudinal direction Z, the number of negative electrode tabs 121 on the same side of the negative electrode current collector section 122 can be at least one, for example, one or at least two. If the number of negative electrode tabs 121 on the same side of the negative electrode current collector section 122 is at least two, the at least two negative electrode tabs 121 can increase the current passage area and distribute the current evenly, thereby improving the current uniformity in the negative electrode sheet 12, which has a positive effect on further improving the fast-charging performance of the battery cell 7.

[0150] In some embodiments, one or more negative electrode tabs 121 are located on the same side of the negative electrode current collector section 122, and, for example, all negative electrode tabs 121 are located on the same side of the negative electrode current collector section 122 along the longitudinal direction Z, or alternatively, all negative electrode tabs 121 are arranged on both sides of the negative electrode current collector section 122 along the longitudinal direction Z. The negative electrode tab 121 comprises a second end face 1211 that is connected to the negative electrode current collector section 122, wherein the dimension of the second end face 1211 along the lateral direction Y of the battery cell 7 is W3. The sum of the dimensions of all second end faces 1211 that are located on the same side of the negative electrode current collector section 122 is m*W3.The width of the negative electrode current collector section 122 is W4, where m*W3 / W4 is greater than or equal to 1 / 3 and less than or equal to 1, optionally greater than or equal to 2 / 3 and less than 1, where m represents the number of all negative electrode tabs 121 on the same side of the negative electrode current collector section 122, and m is, for example, greater than or equal to 1. If the number of all negative electrode tabs 121 on the same side of the negative electrode current collector section 122 is 1, then m is 1; if the number of all negative electrode tabs 121 on the same side of the negative electrode current collector section 122 is 2, then m is 2.

[0151] For example, m*W3 / W4 is 1 / 3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.85, 0.9 or lies within a range consisting of any two of the above values.

[0152] If m*W3 / W4 is in the above range, the current passage area of ​​the negative electrode tabs 121 is relatively large, which has a positive effect on improving the fast charging performance of the battery cell 7.

[0153] As in Fig.As shown in Figure 6, in some embodiments the positive electrode tab 111 can be arranged on at least one side, for example on one or both sides, of the positive electrode current collection section 112 along the lateral direction Y. Optionally, the positive electrode tab 111 can be arranged on one side of the positive electrode current collection section 112 along the lateral direction Y. The positive electrode current collection section 112 is arranged along the lateral direction Y on one side of the positive electrode tab 111, which shortens the electron transport path in the positive electrode current collection section 112, resulting in a more uniform current distribution. During the charging process, this enables uniform delithation of the positive electrode active material across the entire positive electrode sheet 11.

[0154] If the positive electrode tab 111 is arranged on at least one side of the positive electrode current collector section 112 along the lateral direction Y, the number of positive electrode tabs 111 on the same side of the positive electrode current collector section 112 is one or more, wherein the positive electrode tab 111 comprises a third end face 1112 which is connected to the positive electrode current collector section 112, wherein the dimension of the third end face 1112 along the longitudinal direction ZL 10 is the sum of the dimensions of all third end faces 1112 on the same side of the positive electrode current collecting section 112 along the longitudinal direction Z s*L 10 is, and the dimension of the positive electrode current collection section 112 along the longitudinal direction Z L1 is, where s*L 10 / L1 is greater than or equal to 1 / 3, optionally greater than or equal to 2 / 3 and less than 1, where s represents the number of all positive electrode tabs 111 on the same side of the positive electrode current collector section 112.

[0155] For example, s*L 10 / L1 1 / 3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.85, 0.9 or lies within a range consisting of any two of the above values.

[0156] If s*L 10 Since / L1 is located in the above area, the current passage area of ​​the positive electrode tab 111 is relatively large, which has a positive effect on improving the fast charging performance of the battery cell 7.

[0157] As in Fig.As shown in Figure 7, in some embodiments the negative electrode tab 121 is arranged on at least one side, for example on one or both sides of the negative electrode current collection section 122 along the lateral direction Y. Optionally, the negative electrode tab 121 is arranged on one side of the negative electrode current collection section 122 along the lateral direction Y, thereby shortening the electron transport path in the negative electrode current collection section 122, resulting in a more uniform current distribution and a lower susceptibility to lithium plating.

[0158] If the negative electrode tab 121 is arranged on at least one side of the negative electrode current collector section 122 along the lateral direction Y, the number of negative electrode tabs 121 on the same side of the negative electrode current collector section 122 is one or more, wherein the negative electrode tab 121 comprises a fourth end face 1212 connected to the negative electrode current collector section 122, the dimension of the fourth end face 1212 being along the longitudinal direction ZL 20 is the sum of the dimensions of all fourth end faces 1212 on the same side of the negative electrode current collecting section 122 along the longitudinal direction Z p*L 20 is, and the dimension of the negative electrode current collection section 122 along the longitudinal direction Z L2 is, where p*L 20 / L2 is greater than or equal to 1 / 3, optionally greater than or equal to 2 / 3 and less than 1, where p represents the number of all negative electrode tabs 121 on the same side of the negative electrode current collector section 122.

[0159] For example, p*L 20 / L2 1 / 3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.85, 0.9 or lies within a range consisting of any two of the above values.

[0160] If p*L 20 Since / L2 is located in the above area, the current passage area of ​​the negative electrode tab 121 is relatively large, which has a positive effect on improving the fast charging performance of the battery cell 7.

[0161] As in Fig.As shown in Figure 8, in some embodiments along the longitudinal direction Z of the battery cell 7, the dimension of the negative electrode film layer 123 is larger than that of the positive electrode film layer 113. The difference between the dimension of the negative electrode film layer 123 and the dimension of the positive electrode film layer 113 is OH1, where OH1 is from 0.5 mm to 3.0 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.0 mm, or in a range consisting of any two of the above values. Along the longitudinal direction Z, both sides of the negative electrode film layer 123 project beyond the positive electrode film layer 113, and each side by OH1 / 2, that is, half a dimension of OH1. Fig. Figure 8 shows OH1 / 2.

[0162] In some embodiments, along the lateral direction Y of the battery cell 7, the dimension of the negative electrode film layer 123 is larger than that of the positive electrode film layer 113. The difference between the dimension of the negative electrode film layer 123 and the dimension of the positive electrode film layer 113 is OH2, where OH2 is 0.5 mm to 3.0 mm, for example 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.0 mm, or in a range consisting of any two of the above values. Along the lateral direction Y, both sides of the negative electrode film layer 123 project beyond the positive electrode film layer 113, and each side by OH2 / 2, that is, half a dimension of OH2. Fig. Figure 8 shows OH2 / 2.

[0163] In some embodiments, the positive electrode tab 111 is connected to both sides of the positive electrode current collector section 112 along the longitudinal direction Z, and the negative electrode tab 121 is connected to both sides of the negative electrode current collector section 122 along the longitudinal direction Z. Along the longitudinal direction Z of the battery cell 7, the dimension of the negative electrode film layer 123 is larger than the dimension of the positive electrode film layer 113, and the difference between the dimension of the negative electrode film layer 123 and the dimension of the positive electrode film layer 113 is OH1. Along the transverse direction Y of the battery cell 7, the dimension of the negative electrode film layer 123 is larger than the dimension of the positive electrode film layer 113, and the difference between the dimension of the negative electrode film layer 123 and the dimension of the positive electrode film layer 113 is OH2, where OH1 is larger than OH2.The positive electrode tab 111 and the negative electrode tab 121 are in . Fig. 8 not shown.

[0164] The negative electrode tab 121 is located on both sides of the negative electrode current collector section 122 along the longitudinal direction Z, and the width of the negative electrode current collector section 122 is greater than the width of the negative electrode tab 121. Therefore, the current-pass area of ​​the negative electrode current collector section 122 is larger than the current-pass area of ​​the negative electrode tab 121. Due to the different current-pass areas, the current density in the connection area between the negative electrode tab 121 and the negative electrode current collector section 122 increases significantly, and lithium plating and other problems occur more frequently in this area. In the embodiments of the present application, however, OH1 is set larger than OH2, thereby improving the ability of the negative electrode film layer 123 to absorb lithium ions along the longitudinal direction Z.This particularly improves the ability of the negative electrode film layer 123 to absorb lithium ions near the negative electrode tab 121, thereby reducing the risk of lithium plating and improving the operational reliability of the battery cell 7.

[0165] In other embodiments, the positive electrode tab 111 is connected to one side of the positive electrode current collector section 112 along the lateral direction Y, and the negative electrode tab 121 is connected to one side of the negative electrode current collector section 122 along the lateral direction Y. Along the lateral direction Y of the electrode arrangement 10, the dimension of the negative electrode film layer 123 is larger than the dimension of the positive electrode film layer 113, and the difference between the dimensions of the negative electrode film layer 123 and the positive electrode film layer 113 is OH2. Along the longitudinal direction Z of the electrode arrangement 10, the dimension of the negative electrode film layer 123 is larger than the dimension of the positive electrode film layer 113, and the difference between the dimensions of the negative electrode film layer 123 and the positive electrode film layer 113 is OH. 1,where OH2 is larger than OH1. Of course, OH1 can also be larger than OH2.

[0166] The negative electrode tab 121 is located on one side of the negative electrode current collector section 122 along the lateral direction Y, and the length of the negative electrode current collector section 122 is greater than the length of the negative electrode tab 121. Therefore, the current-pass area of ​​the negative electrode current collector section 122 is larger than the current-pass area of ​​the negative electrode tab 121. Due to the different current-pass areas, the current density in the connection area between the negative electrode tab 121 and the negative electrode current collector section 122 increases significantly, and lithium plating and other problems occur more frequently in this area. In the embodiments of the present application, OH2 is set larger than OH1, thereby improving the ability of the nearby negative electrode film layer 123 to absorb lithium ions along the lateral direction Y.In particular, the ability of the negative electrode film layer 123 to absorb lithium ions in the area near the negative electrode tab 121 can be improved, thereby reducing the risk of lithium plating and improving the operational reliability of the battery cell 7.

[0167] As in the Fig. 2 and Fig. In some embodiments, the battery cell 7 shown in Figure 9 can comprise a housing 20.

[0168] In some embodiments, the housing 20 of the battery cell 7 can be a hard housing, for example, a hard plastic housing, an aluminum housing, a steel housing, etc. The housing 20 of the battery cell 7 can also be a soft packaging, for example, a bag-like soft packaging. The material of the soft packaging can be plastic, for example, at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0169] The housing 20 has a hollow structure and the housing 20 can be used to encapsulate the electrode arrangement 10 and the electrolyte solution.

[0170] The method for producing the battery cell 7 according to the embodiments of the present application is known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte solution can be assembled to form a battery cell 7. For example, the positive electrode sheet, the separator, and the negative electrode sheet can be formed into an electrode assembly 10 by a stacking process, the electrode assembly 10 can be inserted into a housing 20, and after drying, an electrolyte solution can be injected, and a battery cell 7 can be obtained by vacuum sealing, standing, formation, and shaping, etc.

[0171] In some embodiments, the housing 20 comprises a housing body 21 and an end cover 22, wherein the housing body 21 has an opening and the end cover 22 covers the opening.

[0172] The shape of the housing body 21 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, a cylindrical housing body can be selected; if the electrode assembly 10 has a cuboid structure, a cuboid housing body can be selected. Optionally, both the electrode assembly 10 and the housing body 21 can have a cuboid structure.

[0173] In some embodiments, the housing body 21 is made of steel. Steel has high mechanical strength and does not deform easily, which can improve the operational reliability and cycle life of the battery cell. Optionally, steel constitutes the largest proportion of material in the housing body 21.

[0174] Optionally, the thickness of the casing 21 is 0.1 mm to 0.5 mm, and optionally 0.2 mm to 0.35 mm. For example, the thickness of the casing 21 could be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or a range consisting of any two of the above values. If the thickness of the casing 21 is within the above range, the mechanical strength of the casing 21 is relatively high, which can improve the operational reliability and cycle life of the battery cell 7. Furthermore, the casing 21 occupies less space, and its internal volume is relatively large, which contributes to increasing the energy density of the battery cell 7.

[0175] If the housing body 21 has a cuboid structure, the housing body 21 comprises two first housing sections 211 and two second housing sections 212, wherein the two first housing sections 211 are arranged opposite each other, the two second housing sections 212 are arranged opposite each other, the first housing sections 211 are connected between the two second housing sections 212, and the area of ​​the first housing section 211 is larger than the area of ​​the second housing section 212.

[0176] In some embodiments, the thickness of the first housing section 211 is 0.1 mm to 0.5 mm, optionally 0.2 mm to 0.35 mm. The first housing section 211 is thinner and the housing body 21 occupies less space, which can further improve the energy density of the battery cell 7.

[0177] In some embodiments, the thickness of the second housing section 212 is 0.1 mm to 0.5 mm, optionally 0.2 mm to 0.35 mm.

[0178] In some embodiments, the thickness of the first housing section 211 is greater than or equal to the thickness of the second housing section 212. In other embodiments, the thickness of the first housing section 211 is less than the thickness of the second housing section 212.

[0179] In some embodiments, the base material of the housing body 21 comprises steel. Steel exhibits high mechanical strength and does not deform easily, which can improve the operational reliability and cycle life of the battery cell. In the embodiments of the present application, the base material is defined as the material with the highest proportion in the housing body 21.

[0180] In some embodiments, the battery cell 7 also includes a positive electrode terminal 31, and the positive electrode terminal 31 is electrically connected to the positive electrode tab 111. Optionally, the positive electrode terminal 31 and the positive electrode tab 111 are welded together, and the positive electrode terminal 31 and the positive electrode tab 111 can be connected via an adapter or without an adapter; optionally, the positive electrode terminal 31 and the positive electrode tab 111 are not connected via an adapter, i.e., the positive electrode terminal 31 and the positive electrode tab 111 are directly welded together, which can reduce the resistance at the connection and has a positive effect on reducing the overall internal resistance of the battery cell 7.

[0181] Optionally, the number of positive electrode terminals 31 is at least one, optionally at least two. For example, if two positive electrode terminals 31 are present, the two positive electrode terminals 31 are located on either side of the positive electrode current collector section.

[0182] Optionally, the number of positive electrode terminals 31 on the same side of the positive electrode current collection section 112 is at least one, optionally at least two. The at least two positive electrode terminals 31 can increase the current-carrying capacity of the positive electrode terminals 31.

[0183] Optionally, the current-carrying area of ​​a single positive electrode terminal 31 is greater than or equal to 200 mm². 2 , optionally from 200 mm 2 up to 800 mm 2The current-passing area of ​​the positive electrode terminal 31 can be understood as the cross-sectional area of ​​the positive electrode terminal 31, and the cross-sectional area runs perpendicular to the thickness direction of the positive electrode terminal 31.

[0184] For example, the current-carrying area of ​​a single positive electrode terminal can be 31,200 mm². 2 , 210mm 2 , 250 mm 2 , 280 mm 2 , 300 mm 2 , 320 mm 2 , 350 mm 2 , 380 mm 2 400 min 2 , 450 mm 2 , 500 mm 2 , 550 mm 2 , 600 mm 2 , 650 mm 2 , 700 mm 2 , 750 mm 2 , 800 mm 2 or lie within a range consisting of any two of the above values.

[0185] In some embodiments, the battery cell 7 also includes a negative electrode terminal 32, and the negative electrode terminal 32 is electrically connected to the negative electrode tab 121. Optionally, the negative electrode terminal 32 and the negative electrode tab 121 are welded together, and the negative electrode terminal 32 and the negative electrode tab 121 can be connected to each other via an adapter or without an adapter; optionally, the negative electrode terminal 32 and the negative electrode tab 121 are not connected to each other via an adapter, i.e., the negative electrode terminal 32 and the negative electrode tab 121 are welded directly, which reduces the resistance at the connection, thus positively reducing the overall internal resistance of the battery cell 7.

[0186] Optionally, the number of negative electrode terminals 32 is at least one, optionally at least two. For example, if two negative electrode terminals 32 are present, the two negative electrode terminals 32 are located on opposite sides of the negative electrode current collector section. By way of example, the battery cell 7 comprises two positive electrode terminals 31 and two negative electrode terminals 32. The two positive electrode terminals 31 are located on opposite sides of the positive electrode current collector section, while the two negative electrode terminals 32 are also located on opposite sides of the negative electrode current collector section. It is understood that one side of the battery cell 7 has one positive electrode terminal 31 and one negative electrode terminal 32, while the other side has one positive electrode terminal 31 and one negative electrode terminal 32. Fig.Figure 9 shows that the battery cell 7 comprises two positive electrode terminals 31 and two negative electrode terminals 32.

[0187] Optionally, the number of negative electrode terminals 32 on the same side of the negative electrode current collection section 122 is at least one, optionally at least two. The at least two negative electrode terminals 32 can increase the current-carrying capacity of the negative electrode terminals 32.

[0188] Optionally, the current-carrying area of ​​the individual negative electrode terminal 32 can be greater than or equal to 200 mm². 2 , optionally from 200 mm 2 up to 800 mm 2 The current-pass area of ​​a negative electrode terminal 32 can be understood as the cross-sectional area of ​​the negative electrode terminal 32, and the cross-sectional area runs perpendicular to the thickness direction of the negative electrode terminal 32.

[0189] For example, the current-carrying area of ​​a single negative electrode terminal can be 32,200 mm². 2 , 210 mm 2 , 250 min 2 , 280 mm 2 , 300 mm 2 , 320 min 2 , 350 mm 2 , 380 mm 2 , 400 mm 2 , 450 mm 2 , 500 mm 2 , 550 mm 2 , 600 mm 2 , 650 mm 2 , 700 mm 2 , 750 mm 2 , 800 mm 2 or lie within a range consisting of any two of the above values. [Positive electrode sheet]

[0190] The positive electrode sheet comprises a positive electrode current collector section and a positive electrode film layer, which is arranged on at least one surface of the positive electrode current collector section and comprises a positive electrode active material. For example, the positive electrode current collector section has two surfaces that are opposite each other along its thickness direction, and the positive electrode film layer is arranged on one or both of the two opposite surfaces of the positive electrode current collector section.

[0191] The upper charging voltage and the discharge cut-off voltage of the battery cell differ depending on the positive electrode active material. For example, if the phosphate material includes lithium iron phosphate, the upper charging voltage can be 3.65 V and the discharge cut-off voltage 2.0 V. If the phosphate material also includes, for example, lithium manganese iron phosphate, the upper charging voltage can be 4.3 V and the discharge cut-off voltage 2.0 V. The state of the battery cell is explained below using the example of an upper charging voltage of 3.65 V and a discharge cut-off voltage of 2.0 V: In the embodiments of the present application, the state of charge (SOC) of 100% and the state of charge (SOC) of the battery cell are defined as follows:

[0192] The battery cell is charged at a constant charging current rate of 0.33C up to the upper charging limit voltage and then further charged at a constant voltage down to 0.05C, which corresponds to a state of 100% SOC (State of Charge) of the battery cell. The battery cell is then discharged at a constant discharge rate of 0.33C down to the final voltage, which corresponds to a state of 0% SOC of the battery cell.

[0193] In some embodiments, the compaction density of the positive electrode film layer when the battery cell is at a state of charge (SOC) of 100% is 2.50 g / cm³. 3 up to 2.80 g / cm³ 3 ; optional 2.55 g / cm² 3 up to 2.70 g / cm³ 3 When the battery cell is at a state of charge (SOC) of 100%, the density of the positive electrode film layer is, for example, 2.50 g / cm³. 3 , 2.52 g / cm³ 3 , 2.55 g / cm³ 3 , 2.56 g / cm³ 3 , 2.57 g / cm³ 3 , 2.58 g / cm³ 3, 2.60 g / cm³ 3 , 2.62 g / cm³ 3 , 2.65 g / cm³ 3 , 2.68 g / cm³ 3 , 2.70 g / cm³ 3 , 2.72 g / cm³ 3 , 2.75 g / cm³ 3 , 2.78 g / cm³ 3 , 2.80 g / cm³ 3 or lies within a range consisting of any two of the values ​​mentioned above.

[0194] If the density of the positive electrode film layer is within the aforementioned range, this is advantageous for increasing the energy density of the battery cell; and because the positive electrode active material in the positive electrode film layer is relatively densely packed, and the contact resistance between the particles is low, the resistance of the electrode sheet can be further reduced, thereby decreasing heat generation during fast charging. By adjusting the density of the positive electrode film layer to an appropriate range, the battery cell therefore exhibits both high energy density and high charging rate performance.

[0195] In some embodiments, the one-sided coating weight of the positive electrode film layer is 160 mg / 1540.25 mm². 2 up to 340 mg / 1540.25 mm 2For example, the coating weight of the positive electrode film layer on one side is 160 mg / 1540.25 mm². 2 , 170 mg / 1540.25 mm 2 , 180 mg / 1540.25 mm 2 , 190 mg / 1540.25 mm 2 , 200 mg / 1540.25 mm 2 , 210 mg / 1540.25 mm 2 , 220 mg / 1540.25 mm 2 , 230 mg / 1540.25 mm 2 , 240 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 270 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 310 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 330 mg / 1540.25 mm 2 , 340 mg / 1540.25 mm 2 or lies within a range consisting of any two of the values ​​mentioned above.

[0196] If the one-sided coating weight of the positive electrode film layer is within the range mentioned above, the amount of heat generated per unit area of ​​the positive electrode sheet is not too large, so that the energy density and the charging rate performance of the battery cell can be increased simultaneously.

[0197] In the embodiments of the present application, the density of the positive electrode film layer in the battery cell at a state of charge (SOC) of 100% has the meaning known in the art. The positive electrode sheet is thus removed from the battery cell at a state of charge (SOC) of 100%, and the density of the positive electrode film layer is measured. For example, the positive electrode sheet coated on one side (in the case of a double-sided electrode sheet, the positive electrode film layer can first be wiped off one side) is taken, then punched into small discs with an area of ​​S1, and weighed, with its weight recorded as M1. Subsequently, its thickness H1 is measured.The positive electrode film layer of the above-mentioned weighed positive electrode sheet is then wiped off, the positive electrode current collector section is weighed and its weight is recorded as M0, and its thickness H0 is measured. The one-sided coating weight of the positive electrode film layer = (the weight M1 of the positive electrode sheet - the weight M0 of the positive electrode current collector section) / S1, the thickness of the positive electrode film layer = the thickness H1 of the positive electrode sheet - the thickness H0 of the positive electrode current collector section, the compaction density of the positive electrode film layer = the one-sided coating weight of the positive electrode film layer / the thickness of the positive electrode film layer.

[0198] In some embodiments, the powder resistance of the positive electrode active material is 1 Ω·cm to 27.5 Ω·cm, optionally less than or equal to 20 Ω·cm, and optionally less than or equal to 11 Ω·cm. For example, the powder resistance of the positive electrode active material can be 27.5 Ω·cm, 20 Ω·m, 19 Ω·cm, 18 Ω·cm, 17 Ω·cm, 16 Ω·cm, 15 Ω·cm, 14 Ω·cm, 13 Ω·cm, 12 Ω·cm, 11 Ω·cm, 10 Ω·m, 9 Ω·cm, 8 Ω·cm, 7 Ω·cm, 6 Ω·cm, 5 Ω·cm, 4 Ω·m, 3 Ω·cm, 2 Ω·cm, 1 Ω·cm or lie in a range consisting of any two of the above values.

[0199] The powder resistance of the positive electrode active material is relatively low, so the resistance of the positive electrode sheet is relatively low, resulting in less heat generation from the battery cell.

[0200] In the embodiments of the present application, the powder resistance of the material has a meaning known in the art and can be determined using methods and devices known in the art, for example in accordance with the test standard GB / T30835-2014 with a powder resistance measuring device PRCD1100.

[0201] In some embodiments, the powder compaction density of the positive electrode active material at 30000 N is greater than or equal to 2.46 g / cm³. 3 , optionally from 2.46 g / cm² 3 up to 2.8 g / cm³ 3 For example, the powder compaction density of the positive electrode active material at 30000 N is 2.46 g / cm³. 3 , 2.47 g / cm³ 3 , 2.48 g / cm³ 3 , 2.49 g / cm³ 3 , 2.5 g / cm³ 3 , 2.51 g / cm³ 3 , 2.55 g / cm³ 3 , 2.58 g / cm³ 3 , 2.60 g / cm³ 3 , 2.65 g / cm³ 3 , 2.68 g / cm³ 3 , 2.70 g / cm³ 3 , 2.72 g / cm³ 3 2.75 g / cm²3 , 2.78 g / cm³ 3 , 2.80 g / cm³ 3 or lies within a range consisting of any two of the values ​​mentioned above.

[0202] If the powder compaction density of the positive electrode active material is within the above-mentioned range at 30000 N, the energy density of the battery cell can be increased, and because the positive electrode active material can be stacked more densely in the positive electrode film layer, the contact resistance between the particles is lower, which can further reduce the resistance of the electrode sheet and thus decrease heat generation.

[0203] In the embodiments of the present application, the powder compaction density of the material has a meaning known in the art and can be determined using methods and devices known in the art, as in accordance with test standard GB / T24533-2009. For example, a certain quantity of positive electrode active material is taken as a sample and placed in a mold with a base area of ​​1.327 cm². 2 The powder was inserted into the UTM7305 electronic pressure testing device and subjected to a pressure of 3000 kg (corresponding to 30000 N), held for 30 s, then released and held for 10 s. The powder compaction density of the positive electrode active material under a force of 30000 N was then recorded and calculated.

[0204] In some embodiments, the charging capacity per gram of positive electrode active material at a rate of 0.1 C is 150 mAh / g to 170 mAh / g. For example, the charging capacity per gram of positive electrode active material at a rate of 0.1 C is 150 mAh / g or 151 mAh / g. 152 mAh / g, 153 mAh / g, 154 mAh / g, 155 mAh / g, 156 mAh / g, 157 mAh / g, 158 mAh / g, 159 mAh / g, 160 mAh / g, 161 mAh / g, 162 mAh / g, 163 mAh / g, 164 mAh / g, 165 mAh / g, 166 mAh / g, 167 mAh / g, 168 mAh / g, 169 mAh / g, 170 mAh / g or lies within a range consisting of any two of the above values.

[0205] If the charging capacity per gram of the positive electrode active material at a rate of 0.1 C is within the range mentioned above, the energy density of the battery cell is relatively high.

[0206] In the embodiments of the present application, the capacity of the active material per gram has a meaning known in the art and can be determined using devices and methods known in the art, whereby the test method for the first coulomb efficiency and the first specific discharge capacity in Annex G of the national standard GB / T 24533-2019 can be used, wherein metallic lithium is used as the negative electrode and a sample electrode sheet containing the above material is used as the positive electrode, and the two are assembled to form a half-button cell.At 23 °C ± 2 °C, the half-button cell is charged and discharged at a rate of 0.1 C on a battery tester or other test device with equivalent performance to obtain the capacity of the half-button cell, and then the parameter of the charging capacity per gram is obtained by dividing this capacity by the mass of the active material of the electrode sheet.

[0207] In some embodiments, the mass fraction of the lithium-containing phosphate with an olivine structure in the positive electrode active material can be greater than or equal to 80% and less than or equal to 100%. The positive electrode active material in the present application can be considered a lithium-containing phosphate system with an olivine structure. If the mass fraction of the lithium-containing phosphate with an olivine structure is less than 100%, the positive electrode active material can also comprise, but is not limited to, a commonly used positive electrode active material, for example, at least one of the lithium-containing transition metal oxides.Examples of lithium-containing transition metal oxides may include, but are not limited to, at least one of the following: lithium cobalt oxide; lithium uninicel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.

[0208] Optionally, the mass fraction of the lithium-containing phosphate with olivine structure in the positive electrode active material is 100%.

[0209] In the embodiments of the present application, the lithium-containing phosphate with an olivine structure can consist of phosphate particles or of a material obtained by coating and modifying the phosphate particles. For example, the lithium-containing phosphate with an olivine structure comprises phosphate particles and a coating layer, wherein the surface of the phosphate particles is coated with the coating layer and contains one or more of C, Fe, Ti, Zr, Hf, Ge, and Sn.

[0210] By coating the surface of phosphate particles with the coating layer, the conductivity of the lithium-containing phosphate with olivine structure can be improved, the powder resistance of the material reduced, and the migration rate of the lithium ions increased, thereby improving the fast charging capability of the battery and reducing the amount of heat generated by the battery cell.

[0211] In some embodiments, the phosphate particles comprise a compound with the general formula of Li x1 A y1 Me a M b P 1-c X c Y z , where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3 and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5 and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5, A comprises one or more of Na, K and Mg, Me comprises one or more of Mn, Fe, Co and Ni, M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce, X comprises one or more of S, Si, Cl, B, C, and N, and Y comprises one or more of O and F. The phosphate particles exhibit excellent cycle stability, which has a positive effect on improving the cycle performance of the battery cell.

[0212] Examples of phosphate particles include one or more LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. During the charging and discharging process of a battery cell, deintercalation and intercalation, as well as the consumption of active ions such as lithium, occur, and the molar content of lithium varies depending on the state of discharge of the battery cell. When listing positive electrode active materials such as LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc., the molar content of lithium refers to the initial state of the material, i.e., the state before it is added. The positive electrode active material is used in the battery system. After the charge-discharge cycle, the molar content of lithium may change. When listing positive electrode active materials such as LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc., in the embodiments of the present application, the molar content of oxygen (O) is only a theoretical value.The release of oxygen from the lattice leads to a change in the molar content of oxygen (O), which is why the molar content of oxygen (O) varies in practice. The situations mentioned above all fall within the scope of protection of this application.

[0213] In some embodiments, the coating layer comprises a fast ion conductor with the general formula of Li 3-d Fe 2-d M2 d (PO x2 ) y2 , where M2 comprises one or more of Ti, Zr, Hf, Ge and Sn, and 0 ≤ d ≤ 1, 0< x2 < 5, 0 < y2 ≤ 4.

[0214] An example of a fast ion conductor is a material with a NASICON structure and includes, for example, one or more of lithium iron titanium phosphate Li2FeTi(PO4)3, lithium iron zirconium phosphate Li2FeZr(PO4)3 and lithium iron tin phosphate Li2FeSn(PO4)3.

[0215] The fast ion conductor with NASICON structure is a material with superior ionic conductivity and features numerous three-dimensional diffusion and transport channels for lithium ions. It is characterized by high ionic conduction efficiency and structural stability during multiple deintercalations and intercalations of lithium ions. Surface coating of phosphate particles with a fast ion conductor with NASICON structure significantly increases the lithium ion transport rate during multiple deintercalations and intercalations at the positive electrode, improves the ionic conductivity of the positive electrode active material, and enhances the fast-charging capability of the battery cell. Furthermore, this can increase the capacity per gram and the energy density of the corresponding battery cell.

[0216] In some embodiments, the coating layer also comprises elemental carbon.

[0217] The elemental carbon and the fast ionic conductor can be arranged in layers. For example, the elemental carbon can be used as a separate carbon coating layer, and the fast ionic conductor as a separate fast ionic conductor layer. The surface of the phosphate particles can be coated with the carbon coating layer, and the fast ionic conductor layer is located on the surface of the carbon coating layer, i.e., on the side of the carbon coating layer facing away from the phosphate particles. Alternatively, the surface of the phosphate particles can be coated with the fast ionic conductor layer, and the carbon coating layer is located on the surface of the fast ionic conductor layer, i.e., on the side of the fast ionic conductor layer facing away from the phosphate particles.Of course, the elemental carbon and the fast ion conductor can also be arranged in the same layer.

[0218] Optionally, the surface of the fast ion conductor layer can be coated with a carbon coating layer formed by carbonizing an organic carbon source (e.g., glucose, polyethylene glycol, etc.). The carbon coating layer can partially or completely cover the surface of the ion conductor layer. By applying the carbon coating layer, the electronic conductivity of the phosphate particles can be significantly improved, compensating for their poor electronic conductivity and increasing the energy density of the battery cell.

[0219] In particular, the arrangement of the carbon coating layer enables the positive electrode active material of the present application to have the following advantages:

[0220] The carbon coating layer in the positive electrode active material of the present application provides a suitable channel for electron transport, thereby significantly increasing the electron conductivity during multiple deintercalations and intercalations of lithium, improving the electronic conductivity of the lithium-containing phosphate, improving the charging capability of the corresponding battery cell, and also increasing the energy density.

[0221] The carbon coating layer of the positive electrode active material of the present application is loose and porous, allowing the electrolyte solution to come into complete and effective contact with the lithium-containing phosphate, thus increasing the transport rate of lithium ions at the phase interface and improving the charging capability of the battery cell.

[0222] Coating the surface of the lithium-containing phosphate with a carbon coating layer can not only improve the conductivity of the lithium-containing phosphate, but also improve the structural stability of the positive electrode active material, thereby effectively reducing the iron dissolution of the positive electrode active material during long-term storage and cyclic use of the battery cell, and thus improving the cycle life of the battery cell.

[0223] The positive electrode active material of the present application uses lithium-containing phosphate as a substrate and fully exploits its advantages such as cost-effective production, high operational reliability, and excellent cycle stability, while coating layers (fast ionic conduction layer and carbon coating layer) are used to overcome the disadvantages of poor electronic and ionic conductivity. The battery cell produced from the positive electrode active material of the present application can exhibit improved energy density with excellent cycle performance.

[0224] In the embodiments of the present application, the element content in the positive electrode active material has a meaning known in the art and can be determined using devices and methods known in the art. For example, it is measured by inductively coupled plasma atomic emission spectroscopy (ICP-OES, instrument model: Thermo ICAP7400) with reference to EPA 6010D-2014. After the battery cell is discharged to a state of charge (SOC) of 0%, the positive electrode sheet is removed, cleaned with DMC, and dried. It is then calcined at a high temperature to remove impurities. Next, 0.4 g of positive electrode active material is weighed out and mixed with 10 mL (50% concentration) of aqua regia. It is then placed on a plate at 180 °C for 30 minutes.After digestion on the plate, the volume is made up to 100 mL and the quantitative test is carried out using the standard curve method.

[0225] In some embodiments, the degree of graphitization of the positive electrode active material is 0.15 to 0.32 and optionally 0.19 to 0.26. For example, the degree of graphitization of the positive electrode active material is 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, or lies in a range consisting of any two of the above values.

[0226] If the graphitization level of the positive electrode active material is within the range mentioned above, this is advantageous in order to improve the conductivity of the positive electrode active material, reduce the heat generation of the positive electrode sheet and thus the amount of heat generated by the battery cell.

[0227] In the embodiments of the present application, the higher the degree of graphitization of the material, the lower the degree of disorder. This can be verified according to the test standard JIS / K 0131-1996 (General Rules for X-ray Diffractometry).

[0228] In some embodiments, the mass fraction of the element carbon in the lithium-containing phosphate with olivine structure is 1% to 2%, and the specific surface area of ​​the lithium-containing phosphate with olivine structure is 5 m². 2 / g up to 18 m 2 / G.

[0229] Optionally, the mass fraction of the element carbon in the lithium-containing phosphate with olivine structure is 1% to 2%, and the specific surface area of ​​the lithium-containing phosphate with olivine structure is 7.5 m². 2 / g up to 14 m 2 / G.

[0230] For example, the mass fraction of the element carbon in the lithium-containing phosphate with olivine structure is 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or lies in a range consisting of any two of the above values.

[0231] For example, the specific surface area of ​​lithium-containing phosphate with an olivine structure is 5 m². 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, 9 m 2 / g, 10 m 2 / g, 11 m 2 / g, 12 m 2 / g, 13 m 2 / g, 14 m 2 / g, 15 m 2 / g, 16 m 2 / g, 17 m 2 / g, 18 m 2 / g or lies within a range consisting of any two of the above values.

[0232] The element carbon is primarily present in the coating layer as a carbon coating layer. This carbon coating layer is loose and porous, which increases the specific surface area of ​​the material, improves the effective contact between the electrolyte solution and the phosphate particles, and promotes the transport of lithium ions at the interface. If the mass fraction of the element carbon is within the aforementioned range, the conductivity of the lithium-containing phosphate with an olivine structure can be significantly improved. This, in turn, enhances the ionic and electronic conductivity of the lithium-containing phosphate with an olivine structure, thereby increasing the fast-charging capability and energy density of the battery cell.

[0233] In the embodiments of the present application, the specific surface area of ​​the material has a meaning known in the art and can be determined using devices and methods known in the art, for example according to the test standard GB / T 19587-2017. In this process, the positive electrode active material is used as a sample and the specific surface area is measured using a specific surface and pore size analyzer (model: Tri-Star 3020) from the American manufacturer Micromeritics.

[0234] In some embodiments, the volume distribution particle size of the positive electrode active material meets: 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm.

[0235] For example, the Dv50 value of the positive electrode active material can be 1 µm, 1.1 µm, 1.15 µm, 1.2 µm, 1.25 µm, 1.3 µm, 1.35 µm, 1.4 µm, 1.45 µm, 1.5 µm, 1.55 µm, 1.6 µm, 1.65 µm, 1.7 µm, 1.75 µm, 1.8 µm, 1.85 µm, 1.9 µm, 1.95 µm or 2 µm, or be in a range consisting of any two of the above values.

[0236] For example, the Dv10 value of the positive electrode active material can be 0.4 µm, 0.45 µm, 0.5 µm, 0.55 µm, 0.6 µm, 0.65 µm or 0.7 µm, or in a range consisting of any two of the above values.

[0237] The particle size of the positive electrode active material is relatively small, resulting in a short deintercalation and intercalation pathway for lithium ions within the material and minimal heat generation. Furthermore, the particle size of the aforementioned positive electrode active material is not excessively small, and agglomeration is practically non-existent during processing and manufacturing, ensuring stable performance.

[0238] In the embodiments of the present application, the volume-averaged particle size Dv50 of the material refers to the particle size corresponding to 50% of the volume distribution, and the volume-averaged particle size Dv10 refers to the particle size corresponding to 10% of the volume distribution. The particle sizes can be determined using devices and methods known in the art. For example, the positive electrode active material is used as a sample, and the Dv50 and Dv10 of the particles are measured using a Mastersizer 2000E laser particle size analyzer in accordance with test standard GB / T 19077-2016.

[0239] If the positive electrode active material includes other materials besides the lithium-containing phosphate with olivine structure, the volume distribution particle size of the positive electrode active material refers to the volume distribution particle size of all positive electrode active materials.

[0240] In some embodiments, the lithium-containing phosphate with an olivine structure is in granular form and comprises secondary particles formed by agglomeration of primary particles, the average particle size of which is 200 nm to 500 nm. For example, the average particle size of the primary particles is 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm, or lies within a range consisting of any two of the above values.

[0241] The average particle size of the primary particles is relatively small, which means that the deintercalation and intercalation path of lithium ions in the positive electrode active material is short and the amount of heat generated is low.

[0242] In the embodiments of the present application, primary particles and secondary particles are known terms in the art, and secondary particles refer to particles in an agglomerated state formed by the aggregation of two or more primary particles. The primary and secondary particles can be easily distinguished experimentally (e.g., by taking SEM images with a scanning electron microscope). The average particle size of the primary particles can be determined from the SEM images. The SEM test parameters can be set as follows: the operating voltage (EHT) is 10.00 kV, the InLens detector is used, the working distance is 4.6 mm, and the magnification is 1000x.

[0243] The positive electrode film layer typically comprises several particles of the positive electrode active material; that is, the lithium-containing phosphate with an olivine structure exists as multiple particles of varying sizes, including a smallest and a largest particle. The combination of large and small particles increases the density of the positive electrode film layer and enlarges its pore structure, thereby improving the fast-charging performance of the battery cell.

[0244] In some embodiments, the particle size of the smallest particle in the lithium-containing phosphate with olivine structure is 0.1 µm to 0.4 µm, for example 0.1 µm, 0.15 µm, 0.2 µm, 0.25 µm, 0.3 µm, 0.35 µm, 0.4 µm, or lies within a range consisting of any two of the above values. If the particle size of the smallest particle is within the above range, the particles do not agglomerate as readily during the fabrication of the positive electrode film layer 113.

[0245] In some embodiments, the particle size of the largest particle in the lithium-containing phosphate with olivine structure is 15 µm to 25 µm, for example 15 µm, 16 µm, 17 µm, 18 µm, 19 µm, 20 µm, 21 µm, 22 µm, 23 µm, 24 µm, 25 µm, or lies within a range consisting of any two of the above values. If the particle size of the largest particle is within the above range, the migration path of the lithium ions during the charging and discharging process is not too long, which can improve the fast charging and discharging performance of the battery cell.

[0246] In some embodiments, the positive electrode film layer further comprises one or more ternary materials, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, trilithium citrate, lithium nickelate, and lithium ferrite. The aforementioned materials can be used as lithium replenishers, replenishing the lithium ions for the positive electrode film layer, compensating for the irreversible lithium ion loss in the system, and increasing the capacity and thus the energy density of the battery cell.

[0247] Optionally, the ternary material Li x3 A y3 Ni a3 Co b3 Mn c M3 (1-a3-b3-c3) Y3 z3, where 0 < x3 ≤ 2.1, 0 < y3 ≤ 2.1 and 0.9 ≤ x3 + y3 ≤ 2.1, 0 ≤ a3 ≤ 1, 0 < b3 ≤ 1, 0 ≤ c3 ≤ 1 and 0.1 ≤ a3 + b3 + c3 ≤ 1, 1.8 ≤ z3 ≤ 3.5, A comprises one or more of Na, K and Mg, M3 comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce, and Y3 comprises one or more of O and F.

[0248] For example, the ternary material includes at least one of LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.3 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.80 Co 0.15 Al 0.05 O2.

[0249] In some embodiments, the mass fraction of the lithium supplement in the positive electrode film layer is 0.5% to 5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or lies within a range consisting of any two of the above values. If the mass fraction of the lithium supplement is within the above range, it can replenish lithium ions for the positive electrode film layer, compensate for the irreversible lithium ion loss in the system, and increase the capacity and thus the energy density of the battery cell.

[0250] The lithium supplement can be located in the same layer as the positive electrode active material or in a different layer. If the lithium supplement is located in a different layer than the positive electrode active material, the lithium supplement can be located in a lithium supplement layer, and the positive electrode active material can be located in the positive electrode active material layer. In other words, the positive electrode film layer comprises the lithium supplement layer and the positive electrode active material layer. The positive electrode active material layer can be located on at least one side of the positive electrode current collection section, and the lithium supplement layer can be located between the positive electrode active material layer and the positive electrode current collection section.Alternatively, the lithium supplement layer can be arranged on at least one side of the positive electrode current collection section, and the positive electrode active material layer can be located between the lithium supplement layer and the positive electrode current collection section. Optionally, the lithium supplement layer can be located between the positive electrode active material layer and the positive electrode current collection section. During the cyclic charging and discharging process of the battery cell, the lithium supplement in the lithium supplement layer can be gradually released into the system to compensate for the lithium loss of the battery system.

[0251] In some embodiments, the positive electrode film layer optionally comprises a conductive element of the positive electrode. The embodiments of the present application are not subject to any particular restrictions regarding the type of conductive element of the positive electrode. By way of example, the conductive element of the positive electrode comprises at least one of superconducting carbon, conductive graphite, carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass fraction of the conductive element of the positive electrode is ≤ 5%, based on the mass of the positive electrode film layer.

[0252] In some embodiments, the positive electrode film layer optionally comprises a positive electrode binder. The embodiments of the present application are not subject to any particular restrictions regarding the type of positive electrode binder. By way of example, the positive electrode binder may comprise at least one of the following: polyvinylidene fluoride, polytetrafluoroethylene, a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and a fluorine-containing acrylate resin. In some embodiments, the mass fraction of the positive electrode binder is ≤ 5%, based on the mass of the positive electrode film layer.

[0253] In some embodiments, the positive electrode current collector section can be a metal foil or a composite current collector section. For example, the metal foil can be made of at least one material: aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. The composite current collector section can comprise a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal material of the metal layer can be aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. For example, the polymer base layer can be polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

[0254] In some embodiments, the ratio of the thickness of the positive electrode current collector section to the thickness of the one-sided positive electrode film layer is 0.05 to 0.3. For example, the ratio of the thickness of the positive electrode current collector section to the thickness of the one-sided positive electrode film layer is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, or lies in a range consisting of any two of the above values.

[0255] If the ratio of the thickness of the positive electrode current collection section to the thickness of the one-sided positive electrode film layer is within the range mentioned above, the fast charging capability and the energy density of the battery cell can be increased.

[0256] In some embodiments, the thickness of the positive electrode current collector section is 10 µm to 15 µm and optionally 12 µm to 15 µm. For example, the thickness of the positive electrode current collector section is 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, 12.5 µm, 13 µm, 13.5 µm, 14 µm, 14.5 µm, 15 µm, or lies in a range consisting of any two of the above values.

[0257] If the thickness of the positive electrode current collection section is within the range mentioned above, the positive electrode current collection section exhibits relatively excellent current conductivity and allows for a higher energy density of the battery cell.

[0258] In the embodiments of the present application, the thicknesses of the positive electrode film layer and the positive electrode current collection section have meanings known in the art and can be measured using devices and methods known in the art, for example by measuring the thickness of the positive electrode sheet with a high-precision micrometer, removing the film layer from the surface of the positive electrode current collection section and measuring the thickness of the positive electrode current collection section with the high-precision micrometer, wherein, in the case of single-sided coating of the positive electrode film layer, its thickness corresponds to the difference between the thickness of the positive electrode sheet and that of the positive electrode current collection section, while in the case of double-sided coating, the thickness of the positive electrode film layer corresponds to half of this difference.

[0259] The positive electrode film layer is typically formed by applying a positive electrode paste to the positive electrode current collector section, followed by drying and cold pressing. The positive electrode paste is generally formed by dispersing and uniformly stirring the positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent. The solvent may be, but is not limited to, N-methyl-2-pyrrolidone (NMP).

[0260] The positive electrode sheet does not exclude further additional functional layers besides the positive electrode film layer. For example, in some embodiments, the positive electrode sheet according to the embodiments of the present application also comprises a conductive layer of the positive electrode, which is enclosed between the positive electrode current collection section and the positive electrode film layer and is arranged on the surface of the positive electrode current collection section. In other embodiments, the positive electrode sheet according to the embodiments of the present application further comprises a protective layer that covers the surface of the positive electrode film layer.

[0261] In some embodiments, the positive electrode sheet further comprises a conductive layer of the positive electrode, wherein the conductive layer of the positive electrode is located between the positive electrode film layer and the positive electrode current collection section. The conductive layer of the positive electrode can further improve the conductivity of the positive electrode sheet and reduce the heat generation of the positive electrode sheet, thereby reducing the amount of heat generated by the battery cell.

[0262] In some embodiments, the thickness of the conductive layer of the positive electrode is 0.5 µm to 2 µm. For example, the thickness of the conductive layer of the positive electrode can be 0.5 µm, 0.8 µm, 1 µm, 1.2 µm, 1.5 µm, 1.6 µm, 1.8 µm, 2 µm, or a range consisting of any two of the above values.

[0263] If the thickness of the conductive layer of the positive electrode is within the range mentioned above, the conductivity of the positive electrode sheet can be further improved and the heat generation of the positive electrode sheet reduced, thereby reducing the heat generation of the battery cell, and at the same time increasing the energy density of the battery cell.

[0264] In the embodiments of the present application, the thickness of the conductive layer of the positive electrode has a meaning known in the art and can be determined using devices and methods known in the art. For example, a tomographic examination is carried out on the positive electrode sheet to directly measure the thickness of the conductive layer of the positive electrode.

[0265] In some embodiments, the conductive layer of the positive electrode comprises one or more of a conductive element of the positive electrode and a binder of the positive electrode.

[0266] Optionally, the mass fraction of the conductive material of the positive electrode in the conductive layer of the positive electrode is 30% to 50%. For example, the mass fraction of the conductive material of the positive electrode is 30%, 35%, 40%, 45%, 50%, or lies within a range consisting of any two of the values ​​mentioned above.

[0267] For example, the conductive material of the positive electrode comprises one or more of superconducting carbon, conductive graphite, carbon black, carbon black, Ketjen carbon black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The conductive material of the positive electrode within the conductive layer of the positive electrode can improve the conductivity of the conductive layer of the positive electrode, thereby improving the conductivity of the positive electrode sheet and reducing the amount of heat generated by the battery cell.

[0268] Optionally, the mass fraction of the binder in the conductive layer of the positive electrode is 50% to 70%. For example, it is 50%, 60%, 65%, 70%, or lies within a range consisting of any two of the values ​​mentioned above.

[0269] For example, the positive electrode binder comprises one or more of the following: polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorine-containing acrylate resin. The positive electrode binder in the conductive layer of the positive electrode can improve the bonding performance between the positive electrode current collection section and the positive electrode film layer, and enhance the structural stability of the positive electrode sheet. [Negative electrode sheet]

[0270] The negative electrode sheet comprises a negative electrode current collector section and a negative electrode film layer arranged on at least one surface of the negative electrode current collector section and comprising a negative electrode active material. For example, the negative electrode current collector section has two surfaces that are opposite each other along its thickness direction, and the negative electrode film layer is arranged on one or both of the two opposite surfaces of the negative electrode current collector section.

[0271] In some embodiments, the compaction density of the negative electrode film layer is 1.15 g / cm³. 3 up to 1.36 g / cm³ 3 , optional 1.25 g / cm² 3 up to 1.36 g / cm³ 3When the battery cell is at 100% charge, the density of the negative electrode film layer is, for example, 1.15 g / cm³. 3 , 1.18 g / cm³ 3 , 1.20 g / cm³ 3 , 1.22 g / cm³ 3 , 1.25 g / cm³ 3 , 1.28 g / cm³ 3 , 1.3 g / cm³ 3 , 1.32 g / cm³ 3 , 1.35 g / cm³ 3 , 1.36 g / cm³ 3 or lies within a range consisting of any two of the values ​​mentioned above.

[0272] If the density of the negative electrode film layer is within the range mentioned above, this is advantageous for increasing the energy density of the battery cell; and because the negative electrode active material is packed relatively densely in the negative electrode film layer, and the contact resistance between the particles is low, the resistance of the electrode sheet can be further reduced, thereby decreasing heat generation.

[0273] In the embodiments of the present application, the density of the negative electrode film layer when the battery cell is at 100% charge has a meaning known in the art and can be determined using devices and methods known in the art. The detection method, for example, is the same as the test method for the density of the positive electrode film layer.

[0274] In some embodiments, the one-sided coating weight of the negative electrode film layer is 74 mg / 1540.25 mm². 2 up to 156 mg / 1540.25 mm 2 For example, the one-sided coating weight of the negative electrode film layer is 74 mg / 1540.25 mm². 2 , 80 mg / 1540.25 mm 2 , 85 mg / 1540.25 mm 2 , 90 mg / 1540.25 mm 2 , 95 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 102 mg / 1540.25 mm 2 , 104 mg / 1540.25 mm 2 , 105 mg / 1540.25 mm 2 , 108 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 112 mg / 1540.25 mm 2 , 114 mg / 1540.25 mm 2 , 115 mg / 1540.25 mm 2 , 116 mg / 1540.25 mm 2 , 118 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 122 mg / 1540.25 mm 2 , 125 mg / 1540.25 mm 2 , 128 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 132 mg / 1540.25 mm 2 , 135 mg / 1540.25 mm 2, 137 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 145 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 155 mg / 1540.25 mm 2 , 156 mg / 1540.25 mm 2 or lies within a range consisting of any two of the values ​​mentioned above.

[0275] If the one-sided coating weight of the negative electrode film layer is within the range mentioned above, the amount of heat generated per unit area of ​​the negative electrode sheet is not too large, so that the energy density of the battery cell can be increased at the same time.

[0276] In the embodiments of the present application, the one-sided coating weight of the negative electrode film layer has the meaning known in the art and can be determined using devices and methods known in the art, and the detection method is the same as the above test method for the one-sided coating weight of the film layer.

[0277] In some embodiments, the powder resistance of the negative electrode active material is 0.005 Ω·cm to 0.043 Ω·cm and optionally 0.04 Ω·cm. For example, the powder resistance of the negative electrode active material can be 0.043 Ω·cm, 0.04 Ω·cm, 0.035 Ω·cm, 0.03 Ω·cm, 0.025 Ω·cm, 0.02 Ω·cm, 0.015 Ω·cm, 0.01 Ω·cm, 0.005 Ω·cm, or a range consisting of any two of the above values.

[0278] The powder resistance of the negative electrode active material is relatively low, so the resistance of the negative electrode sheet is relatively low, resulting in less heat generation from the battery cell.

[0279] In the embodiments of the present application, the powder resistance of the negative electrode active material has a meaning known in the art and can be determined using devices and methods known in the art, and the detection method is the same as the test method for the powder resistance of the positive electrode active material.

[0280] In some embodiments, the powder compaction density of the negative electrode active material under a pressure of 20000 N is 1.5 g / cm³. 3 up to 1.85 g / cm³ 3 , optional 1.55 g / cm² 3 up to 1.65 g / cm³ 3For example, the powder compaction density of the negative electrode active material under a pressure of 20000 N is 1.5 g / cm³. 3 , 1.55 g / cm³ 3 , 1.6 g / cm³ 3 , 1.65 g / cm³ 3 , 1.7 g / cm³ 3 , 1.75 g / cm³ 3 , 1.8 g / cm³ 3 , 1.85 g / cm³ 3 or lies within a range consisting of any two of the values ​​mentioned above.

[0281] If the powder compaction density of the negative electrode active material at 20000 N is within the range mentioned above, the energy density of the battery cell can be increased, and because the negative electrode active material can be stacked more densely in the negative electrode film layer, the contact resistance between the particles is lower, which can further reduce the resistance of the electrode sheet and thus decrease heat generation.

[0282] In the embodiments of the present application, the powder compaction density of the material has a meaning known in the art and can be determined using methods and devices known in the art in accordance with test standard GB / T24533-2009. As an example, a specific quantity of negative electrode active material is taken as a sample and placed in a mold with a base area of ​​1.327 cm². 2 The powder was inserted into the UTM7305 electronic pressure testing device and subjected to a pressure of 2000 kg (corresponding to 20000 N), held for 30 s, then released and held for 10 s. The powder compaction density of the negative electrode active material under a force of 20000 N was then recorded and calculated.

[0283] In some embodiments, the charging capacity per gram of negative electrode active material at a rate of 0.1 C is 350 mAh / g to 480 mAh / g. For example, the charging capacity per gram of negative electrode active material at a rate of 0.1 C is 350 mAh / g, 355 mAh / g, 360 mAh / g, 365 mAh / g, 370 mAh / g, 375 mAh / g, 380 mAh / g, 385 mAh / g, 390 mAh / g, 395 mAh / g, 400 mAh / g, 410 mAh / g, 420 mAh / g, 430 mAh / g, 440 mAh / g, 450 mAh / g, 460 mAh / g, 470 mAh / g, 480 mAh / g or lies within a range consisting of any two of the above values.

[0284] If the charging capacity per gram of the negative electrode active material at a rate of 0.1 C is within the range mentioned above, the energy density of the battery cell is relatively high.

[0285] In the embodiments of the present application, the charging capacity per gram of the negative electrode active material at a rate of 0.1 C has a meaning known in the art and can be determined using devices and methods known in the art, and the detection method is the same as the test method for the charging capacity per gram of the positive electrode active material at a rate of 0.1 C.

[0286] In some embodiments, the negative electrode active material comprises a carbon-based material. This carbon-based material exhibits high cycle stability, thereby improving the cycle performance of the battery cell. Optionally, the mass fraction of the carbon-based material in the negative electrode active material can be greater than or equal to 80% and less than or equal to 100%.

[0287] The positive electrode active material of the present application consists mainly of a lithium-containing phosphate system with an olivine structure, while the negative electrode active material consists mainly of a carbon-based material system. The two are used in combination, resulting in a relatively excellent cycle life of the battery cell.

[0288] Optionally, the carbon-based material includes graphite particles, with a graphitization degree of 92.0% to 94.5%. For example, the graphitization degree of the graphite particles is 92.0%, 92.5%, 93%, 93.5%, 94%, or 94.5%, or lies within a range consisting of any two of the above values.

[0289] If the graphitization level of the graphite particles is within the range mentioned above, the graphite particles exhibit excellent conductivity, which reduces the heat generation of the negative electrode sheet and the heat generation of the battery cell, and improves the fast charging performance of the battery cell.

[0290] In some embodiments, the graphite particles comprise synthetic graphite and a carbon coating layer, wherein the synthetic graphite comprises secondary particles, the secondary particles comprising several primary particles, and the surface of the synthetic graphite is coated with the carbon coating layer. The carbon in the carbon coating layer consists mainly of amorphous carbon, which is a transitional carbon material with a very low degree of graphitization and crystallinity, close to an amorphous state (or without a fixed shape and periodic structural regularity). In the present application, the amorphous carbon refers to the product obtained after the carbonization of an organic carbon source.

[0291] The artificial graphite comprises secondary particles and offers more migration pathways for lithium ions, while the migration pathways in the primary particles are shorter, which can improve the lithium ion migration rate. The carbon coating layer has more end faces and defects, increasing the number of sites where lithium ions can deintercalate and intercalate. This makes the carbon coating layer more conductive, which can reduce the internal resistance of the negative electrode sheet and thus the amount of heat generated by the battery cell.

[0292] Optionally, the mass fraction of the carbon coating layer is 2% to 5%, based on the mass of the graphite particles. For example, the mass fraction of the carbon coating layer is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or lies within a range consisting of any two of the values ​​mentioned above.

[0293] If the mass fraction of the carbon coating layer is within the range mentioned above, the internal resistance of the negative electrode sheet can be further reduced and the amount of heat generated by the battery cell can be reduced.

[0294] In the embodiments of the present application, the graphite particles can be produced according to a method known in the art. For example, one production method comprises: providing artificial graphite and an organic carbon source, mixing and carbonizing the two, and forming a carbon coating layer on at least a part of the surface of the artificial graphite particles.

[0295] Optionally, the organic carbon source comprises one or more of coal tar pitch, petroleum pitch, phenolic resin, and coconut shell. Optionally, the organic carbon source also includes petroleum pitch. Optionally, the softening point of coal tar pitch and petroleum pitch is below 250 °C.

[0296] Optionally, the carbonization temperature is 700 °C to 1800 °C. Optionally, the carbonization temperature is 1000 °C to 1300 °C. If the carbonation temperature is within a suitable range, the organic carbon source can be carbonized and a coating layer containing amorphous carbon can be formed on at least part of the surface of the artificial graphite.

[0297] Optionally, the carbonation time can last from 1 hour to 6 hours.

[0298] In some embodiments, the carbon-based material may further comprise natural graphite. In particular, the carbon-based material may comprise graphite particles, or the carbon-based material may comprise graphite particles and natural graphite. Optionally, the carbon-based material consists of graphite particles.

[0299] In some embodiments, the negative electrode active material can also comprise a silicon-based material. The introduction of the silicon-based material can increase the capacity of the negative electrode active material and the energy density of the battery cell.

[0300] Optionally, the mass fraction of the element silicon in the silicon-based material is 0.3% to 10.0% and optionally 1% to 6%, based on the mass of the negative electrode active material. For example, the mass fraction of the element silicon in the silicon-based material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or lies in a range consisting of any two of the above values.

[0301] If the mass fraction of the element silicon in the silicon-based material is within the range mentioned above, the capacity of the negative electrode active material can be increased, thereby improving the energy density of the battery cell.

[0302] Optionally, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite and silicon alloy material.

[0303] In some embodiments, the negative electrode active material can, in addition to the carbon-based material mentioned above and optionally the silicon-based material, comprise at least one tin-based material and lithium titanate. The tin-based material can comprise at least one elemental tin, tin oxide, and tin alloy.

[0304] The qualitative and quantitative determination of the individual substances or elements in the present application can be carried out using suitable equipment and methods known to those skilled in the art. The relevant methods of determination may refer to national and international testing standards as well as national and international company standards. Those skilled in the art may also adjust certain test steps / equipment parameters with regard to test accuracy in order to obtain more precise test results. A single method may be used for the qualitative or quantitative determination, or a combination of several methods may be used.

[0305] For example, the present application can combine the general rules for X-ray diffractometry JIS / K0131-1996 to perform an X-ray powder diffraction test and a qualitative analysis of the negative electrode sheet or negative electrode active material.

[0306] Artificial and natural graphites can be distinguished using SEM cross-sectional images obtained with a scanning electron microscope (SEM). The SEM cross-sectional image of natural graphite shows gaps between the scaly structures, while the SEM cross-sectional image of artificial graphite is dense and shows no obvious gaps. They can also be distinguished using their XRD spectra obtained by X-ray diffraction. The XRD spectrum of natural graphite shows a distinct 2H phase and a 3R phase, while the XRD spectrum of artificial graphite shows only the 2H phase.

[0307] In the embodiments of the present application, the negative electrode film layer comprises at least one film layer, wherein either a single film layer or at least two film layers may be present. Optionally, the negative electrode film layer comprises at least two film layers.

[0308] In the case where the negative electrode film layer comprises a single-layer film, the negative electrode active material in the negative electrode film layer comprises a carbon-based material and optionally a silicon-based material. When using a single-layer film, the volume-averaged particle size Dv50 of the negative electrode active material is 8.2 µm to 13.5 µm. For example, the volume-averaged particle size Dv50 of the negative electrode active material is 8.2 µm, 8.5 µm, 8.8 µm, 9 µm, 9.2 µm, 9.5 µm, 9.8 µm, 10 µm, 10.2 µm, 10.5 µm, 10.8 µm, 11 µm, 11.2 µm, 11.5 µm, 11.8 µm, 12 µm, 12.2 µm, 12.5 µm, 12.8 µm, 13 µm, 13.2 µm or 13.5 µm, or lies in a range consisting of any two of the above values.

[0309] In the case where the negative electrode film layer comprises at least two film layers, the negative electrode active material in the negative electrode film layer comprises a carbon-based material and optionally a silicon-based material. The silicon-based material may be located in one or at least two of the at least two film layers. The negative electrode film layer may comprise two, three, four, or even more film layers.

[0310] In some embodiments, the negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer is arranged on the surface of the negative electrode current collection section, the carbon-based material in the first negative electrode film layer comprises graphite particles, the second negative electrode film layer is connected to the side of the first negative electrode film layer facing away from the negative electrode current collection section, and the carbon-based material in the second negative electrode film layer comprises graphite particles, wherein the graphite particles in the first negative electrode film layer and the graphite particles in the second negative electrode film layer may be the same or different.

[0311] The interface between the first negative electrode film layer and the second negative electrode film layer is regular or irregular, optionally irregular.

[0312] Optionally, the carbon-based material in the first negative electrode film layer also includes natural graphite.

[0313] The negative electrode film layer comprises at least two film layers. This multilayer coating contributes to improving the fast-charging performance of the battery cell. In particular, if there is a difference between the first and second negative electrode film layers, the pore size difference of the negative electrode film layer can be increased, the tortuosity of lithium-ion transport can be reduced, and the fast-charging performance of the battery cell can be improved.

[0314] Optionally, the volume-averaged particle size Dv50 of the negative electrode active material in the first negative electrode film layer is greater than or equal to the volume-averaged particle size Dv50 of the negative electrode active material in the second negative electrode film layer. Furthermore, optionally, the volume-averaged particle size Dv50 of the negative electrode active material in the first negative electrode film layer is greater than the volume-averaged particle size Dv50 of the negative electrode active material in the second negative electrode film layer, which has a beneficial effect on improving the compaction density of the negative electrode film layer. If the negative electrode active material includes graphite particles, the volume-averaged particle size Dv50 of the graphite particles in the first negative electrode film layer is greater than or equal to the volume-averaged particle size Dv50 of the graphite particles in the second negative electrode film layer.

[0315] The particle size in the first and second negative electrode film layers differs, which can improve the fast-charging performance of the battery cell. In particular, during fast charging, the overpotential of the second negative electrode film layer is typically higher, and the bottleneck during fast charging lies mainly in this layer. In the embodiments of the present application, the particle size of the second negative electrode film layer is relatively small, which shortens the solid-phase transport path of the lithium ions, improves fast-charging performance, and reduces the problem of lithium plating on the surface of the negative electrode sheet.

[0316] Optionally, the negative electrode active material in the first negative electrode film layer is in granular form and its volume-averaged particle size Dv50 is 9.5 µm to 18.5 µm and optionally 9.5 µm to 14.6 µm. For example, the volume-averaged particle size of the negative electrode active material in the first negative electrode film layer is 9.5 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, 12.5 µm, 13 µm, 13.5 µm, 14 µm, 14.5 µm, 14.6 µm, 15 µm, 15.5 µm, 16 µm, 16.5 µm, 17 µm, 17.5 µm, 18 µm, 18.5 µm, or lies within a range consisting of any two of the above values. If the first negative electrode film layer includes graphite particles, the volume-averaged particle size Dv50 of the graphite particles in the first negative electrode film layer is 9.5 µm to 18.5 µm and optionally 9.5 µm to 14.6 µm.

[0317] If the volume-averaged particle size Dv50 of the negative electrode active material in the first negative electrode film layer is within the range mentioned above, the solid-phase transport path of the lithium ions can be shortened and the fast charging performance improved; on the other hand, the material does not agglomerate as easily during the manufacturing process, which can improve the stability of the material.

[0318] Optionally, the negative electrode active material in the second negative electrode film layer is in granular form and its volume-averaged particle size Dv50 is 7.8 µm to 14.3 µm and optionally 7.8 µm to 11.3 µm. For example, the volume-averaged particle size Dv50 of the negative electrode active material is 7.8 µm, 8.0 µm, 8.2 µm, 8.5 µm, 8.8 µm, 9 µm, 9.2 µm, 9.5 µm, 9.8 µm, 10 µm, 10.2 µm, 10.5 µm, 10.8 µm, 11 µm, 11.3 µm, 11.2 µm, 11.5 µm, 11.8 µm, 12 µm, 12.2 µm, 12.5 µm, 12.8 µm, 13 µm, 13.2 µm. 13.5 µm, 13.8 µm, 14 µm, 14.1 µm, 14.3 µm, or lies within a range consisting of any two of the above values. If the second negative electrode film layer comprises graphite particles, the volume-averaged particle size Dv50 of the graphite particles in the second negative electrode film layer is 7.8 µm to 14.3 µm, and optionally 7.8 µm to 11.3 µm.

[0319] If the volume-averaged particle size Dv50 of the negative electrode active material in the second negative electrode film layer lies within the aforementioned range, the solid-phase transport path of the lithium ions can be shortened and the fast-charging performance improved; furthermore, the material does not agglomerate as easily during the manufacturing process, which can improve the material's stability; and even moreover, combining the negative electrode active material in the second negative electrode film layer and the negative electrode active material in the first negative electrode film layer within the aforementioned range of volume-averaged particle size is advantageous for creating a gradient pore difference between the second negative electrode film layer and the first negative electrode film layer, reducing the tortuosity of lithium ion transport and improving the fast-charging performance of the battery cell.

[0320] In the embodiments of the present application, the volume-averaged particle size Dv50 of the negative electrode active material has a meaning known in the art and can be determined using devices and methods known in the art, and the detection method is the same as the test method for the volume-averaged particle size Dv50 of the above-mentioned positive electrode active material.

[0321] Optionally, the bulk density of the carbon-based material in the first negative electrode film layer is less than or equal to the bulk density of the carbon-based material in the second negative electrode film layer. The bulk density can reflect the packing density of the active material in the film layer. If the bulk density of the carbon-based material in the second negative electrode film layer is greater than the bulk density of the carbon-based material in the first negative electrode film layer, the second negative electrode film layer is more densely packed, thus increasing the energy density of the battery cell. The first negative electrode film layer is relatively thinly packed and has more pores, which can improve the fast-charging performance of the battery cell.If the negative electrode active material comprises graphite particles, the bulk density of the graphite particles in the first negative electrode film layer is less than or equal to the bulk density of the graphite particles in the second negative electrode film layer.

[0322] Optionally, the bulk density of the carbon-based material in the first negative electrode film layer is 0.82 g / cm³. 3 up to 1.21 g / cm³ 3 , for example 0.82 g / cm³ 3 , 0.85 g / cm³ 3 , 0.88 g / cm³ 3 , 0.90 g / cm³ 3 , 0.92 g / cm³ 3 , 0.95 g / cm³ 3 , 0.98 g / cm³ 3 , 1.00 g / cm² 3 , 1.05 g / cm³ 3 , 1.08 g / cm³ 3 , 1.10 g / cm³ 3 , 1.12 g / cm³ 3 , 1.15 g / cm³ 3 , 1.18 g / cm³ 3 , 1.20 g / cm³ 3 , 1.21 g / cm³ 3or lies within a range consisting of any two of the values ​​mentioned above. If the bulk density of the carbon-based material in the first negative electrode film layer is within a suitable range, the fast-charging performance of the battery cell can be improved.

[0323] Optionally, the bulk density of the carbon-based material in the second negative electrode film layer is 0.90 g / cm³. 3 up to 1.25 g / cm³ 3 , for example 0.90 g / cm² 3 , 0.92 g / cm³ 3 , 0.95 g / cm³ 3 , 0.98 g / cm³ 3 1.00 g / cm² 3 , 1.05 g / cm³ 3 , 1.08 g / cm³ 3 , 1.10 g / cm³ 3 , 1.12 g / cm³ 3 , 1.15 g / cm³ 3 , 1.18 g / cm³ 3 , 1.20 g / cm³ 3 , 1.21 g / cm³ 3 , 1.22 g / cm³ 3 , 1.23 g / cm³ 3 , 1.24 g / cm³ 3 , 1.25 g / cm³ 3or lies within a range consisting of any two of the values ​​mentioned above. If the bulk density of the carbon-based material is in the second negative

[0324] If the electrode film layer lies within a suitable area, the energy density of the battery cell can be increased.

[0325] In the embodiments of the present application, the bulk density of a material has a meaning known in the art and can be measured using equipment and methods known in the art. By way of example, it can be measured using a powder bulk density test device, as described in GB / T5162-2006. The test device can be the Bettersize BT-301.

[0326] Optionally, the ratio of the thickness of the second negative electrode film layer to the thickness of the first negative electrode film layer is 3:7 to 7:3 and optionally 4:6 to 6:4. For example, the ratio of the thickness of the second negative electrode film layer to the thickness of the first negative electrode film layer could be 3:7, 4:6, 5:5, 6:4, 7:3, or a range consisting of any two of the above values. By adjusting the ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer, the gradient pore difference between the upper and lower layers can be further increased, the tortuosity of lithium-ion transport reduced, and the fast-charging capability of the battery cell improved.

[0327] In some embodiments, the thickness of the first negative electrode film layer after 10 cycles of the complete charge-discharge test of the battery cell at the beginning of life (BOL) is 15 µm to 65 µm, for example 15 µm, 17 µm, 18 µm, 20 µm, 25 µm, 30 µm, 35 µm, 40 µm, 45 µm, 50 µm, 55 µm, 57 µm, 58 µm, 60 µm, 61 µm, 62 µm, 63 µm, 64 µm, 65 µm, or lies in a range consisting of any two of the above values. If the thickness of the first negative electrode film layer is within the range mentioned above, the gradient pore difference between the first negative electrode film layer and the second negative electrode film layer can be increased, the tortuosity of lithium ion transport can be reduced, and the fast charging capability of the battery cell can be improved.

[0328] In some embodiments, the thickness of the second negative electrode film layer after 10 cycles of the complete charge-discharge test of the battery cell at the beginning of life (BOL) is 15 µm to 65 µm, for example 15 µm, 17 µm, 18 µm, 20 µm, 25 µm, 30 µm, 35 µm, 40 µm, 45 µm, 50 µm, 55 µm, 57 µm, 58 µm, 60 µm, 61 µm, 62 µm, 63 µm, 64 µm, 65 µm or lies in a range consisting of any two of the above values. If the thickness of the second negative electrode film layer is within the range mentioned above, the gradient pore difference between the first negative electrode film layer and the second negative electrode film layer can be increased in a controlled manner, the tortuosity of lithium ion transport can be reduced, and the fast charging capability of the battery cell can be improved.

[0329] In the embodiments of the present application, for example, an upper charging limit voltage of the battery of 3.65 V and a discharge cut-off voltage of the battery of 2.0 V are explained:

[0330] The BOL test steps are as follows: The battery is charged at 25 °C at a rate of 0.33 C of its nominal capacity to 3.65 V. It is then charged at a constant voltage of 3.65 V to 0.05 C. After a 10-minute rest period, the battery is discharged at a rate of 0.33 C to 2.0 V. The battery is then left to rest again for 10 minutes. This charge-discharge process is defined as one cycle and is repeated 10 times. The battery is then charged at a rate of 0.33 C of its nominal capacity to 3.65 V and subsequently charged at a constant voltage of 3.65 V to 0.05 C. This corresponds to the BOL full charge state. At the BOL full charge state, the negative electrode sheet is removed. The cross-section of the central region of the negative electrode sheet in the thickness direction is examined using a tomographic scanning electron microscope.The first and second negative electrode film layers are distinguished by their interfaces. The thicknesses of both layers are measured. For example, the thicknesses of the first negative electrode film layer are measured at 10 positions, and the average value is calculated as the average thickness of the first negative electrode film layer. Similarly, the thicknesses of the second negative electrode film layer are measured at 10 positions, and the average value is calculated as the average thickness of the second negative electrode film layer.

[0331] In some embodiments, the thickness of the first negative electrode film layer after the complete charge-discharge test of the battery cell at the end of life (EOL) is 15 µm to 70 µm, for example 15 µm, 16 µm, 17 µm, 18 µm, 19 µm, 20 µm, 21 µm, 22 µm, 23 µm, 24 µm, 25 µm, 26 µm, 27 µm, 28 µm, 29 µm, 30 µm, 35 µm, 40 µm, 43 µm, 45 µm, 50 µm, 55 µm, 60 µm, 65 µm. 66 µm, 67 µm, 68 µm, 69 µm, 70 µm, or lies within a range consisting of any two of the above values. If the thickness of the first negative electrode film layer is within the above range, the gradient pore difference between the upper and lower layers of the first and second negative electrode film layers can be controlled and increased, reducing the tortuosity of lithium ion transport and improving the fast-charging capability of the battery cell.

[0332] In some embodiments, the thickness of the second negative electrode film layer after the complete charge-discharge test of the battery cell at the end of life (EOL) is 15 µm to 70 µm, for example 15 µm, 16 µm, 17 µm, 18 µm, 19 µm, 20 µm, 21 µm, 22 µm, 23 µm, 24 µm, 25 µm, 26 µm, 27 µm, 28 µm, 29 µm, 30 µm, 35 µm, 40 µm, 43 µm, 45 µm, 50 µm, 55 µm, 60 µm, 65 µm. 66 µm, 67 µm, 68 µm, 69 µm, 70 µm, or lies within a range consisting of any two of the above values. If the thickness of the second negative electrode film layer is within the above range, the gradient pore difference between the upper and lower layers of the first and second negative electrode film layers can be increased in a controlled manner, reducing the tortuosity of lithium ion transport and improving the fast-charging capability of the battery cell.

[0333] In the embodiments of the present application, for example, an upper charging limit voltage of the battery of 3.65 V and a discharge cut-off voltage of the battery of 2.0 V are explained:

[0334] The steps of the complete end-of-life charge-discharge test are as follows: The battery is charged at 60°C at a rate of 0.33C to 3.65V of its nominal capacity. It is then charged at a constant voltage of 3.65V to 0.05C. After a 10-minute rest period, the battery is discharged at a rate of 0.33C to 2.0V. It is then left to rest again for 10 minutes. This charge-discharge process is defined as one cycle and is repeated until the battery capacity has dropped to 80% of its nominal capacity. The battery is then charged at 25°C at a constant current of 0.33C to 3.65V. At a constant voltage, it is charged at a rate of 0.05C to 3.65V. This corresponds to the EOL full charge state. At the EOL full charge state, the negative electrode sheet is removed. The cross-section of the central region of the negative .The electrode sheet is examined in the thickness direction using a tomographic scanning electron microscope. The first and second negative electrode film layers are distinguished based on their interfaces. The thicknesses of both layers are measured. For example, the thicknesses of the first negative electrode film layer are measured at 10 positions, and the average value is calculated as the average thickness of the first negative electrode film layer. Similarly, the thicknesses of the second negative electrode film layer are measured at 10 positions, and the average value is calculated as the average thickness of the second negative electrode film layer.

[0335] In some embodiments, if the negative electrode film layer is a single-layer film layer (unlike the double-layer film layer mentioned above), it also comprises a lithium-containing binder. Optionally, the mass fraction of the lithium-containing binder, based on the mass of the negative electrode film layer, is 0.1% to 1%. By way of example, the mass fraction of the lithium-containing binder, based on the mass of the negative electrode film layer, is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or lies in a range consisting of any two of the values ​​mentioned above.The lithium element in the lithium-containing binder can be present in ionic form, thereby increasing the number of lithium ions that can move freely within the negative electrode film layer, shortening the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increasing the rate of deintercalation and intercalation of lithium ions, and improving the fast-charging performance of the battery cell. Optionally, the negative electrode film layer can also include a negative electrode binder. For example, the negative electrode binder may include at least one of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0336] Optionally, the mass fraction of lithium in the lithium-containing binder is 3% to 10%. For example, the mass fraction of lithium in the lithium-containing binder is 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or lies within any two of the values ​​mentioned above. The mass fraction of lithium is calculated relative to the mass of the lithium-containing binder. If the mass fraction of lithium is within the range mentioned above, the number of lithium ions freely moving within the negative electrode film layer can be relatively large. This further reduces the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increases the deintercalation and intercalation rate of the lithium ions, and improves the fast-charging performance of the battery cell.

[0337] For example, the lithium-containing binder comprises a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and hydroxyethyl acrylate monomer, the molar ratio of the lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and hydroxyethyl acrylate monomer is 30% to 50%: 15% to 45%: 5% to 20%: 20% to 35%. For example, the molar ratio of the lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and hydroxyethyl acrylate monomer is 35%:30%:15%:20% or 40%:20%:10%:30% or 45%:15%:20%:20%, etc.

[0338] The lithium-containing binder in the above material can provide a specific amount of lithium ions to the negative electrode film layer, thus improving the fast-charging performance of the battery cell. It does not swell as easily during charging and discharging and exhibits a stable structure, thereby improving the cycle life of the negative electrode film layer during fast charging and discharging.

[0339] In other embodiments, if the negative electrode film layer comprises at least two film layers, the negative electrode film layer also comprises a lithium-containing binder.

[0340] Optionally, the first negative electrode film layer also includes a first lithium-containing binder, and the second negative electrode film layer also includes a second lithium-containing binder, with the mass fraction of the first lithium-containing binder relative to the mass of the first negative electrode film layer being less than or equal to the mass fraction of the second lithium-containing binder relative to the mass of the second negative electrode film layer. Furthermore, optionally, the mass fraction of the first lithium-containing binder relative to the mass of the first negative electrode film layer is less than the mass fraction of the second lithium-containing binder relative to the mass of the second negative electrode film layer.

[0341] The mass fraction of the second lithium-containing binder in the second negative electrode film layer is relatively high, and the second lithium-containing binder provides the second negative electrode film layer with a relatively larger number of freely moving lithium ions, which can further improve the fast charging performance of the battery cell.

[0342] Optionally, the mass fraction of the first lithium-containing binder, relative to the mass of the first negative electrode film layer, is 0.1% to 1%. For example, the mass fraction of the first lithium-containing binder, relative to the mass of the first negative electrode film layer, is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or lies within a range consisting of any two of the values ​​mentioned above. The lithium element in the first lithium-containing binder can be present in ionic form, thereby increasing the number of lithium ions that can move freely within the negative electrode film layer, reducing the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increasing the rate of deintercalation and intercalation of lithium ions, and improving the fast-charging performance of the battery cell.

[0343] Optionally, the mass fraction of lithium in the first lithium-containing binder is 3% to 10%, and optionally 3% to 8%. For example, the mass fraction of lithium in the first lithium-containing binder is 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or lies within any two of the values ​​mentioned above. If the mass fraction of lithium is within the range mentioned above, the number of lithium ions freely moving within the negative electrode film layer can be relatively large. This further reduces the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increases the deintercalation and intercalation rate of the lithium ions, and improves the fast-charging performance of the battery cell.

[0344] For example, the first lithium-containing binder comprises a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 30% to 50%: 15% to 45%: 5% to 20%: 20% to 35%. For example, the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20% or 40%:20%:10%:30% or 45%:15%:20%:20% etc.

[0345] The lithium-containing binder in the above material can provide a specific amount of lithium ions to the negative electrode film layer, thus improving the fast-charging performance of the battery cell. It does not swell as easily during charging and discharging and exhibits a stable structure, thereby improving the cycle life of the negative electrode film layer during fast charging and discharging.

[0346] Optionally, the mass fraction of the second lithium-containing binder, relative to the mass of the second negative electrode film layer, is 0.1% to 1%. For example, the mass fraction of the second lithium-containing binder, relative to the mass of the second negative electrode film layer, is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or lies within any two of the values ​​mentioned above. The lithium element in the second lithium-containing binder can be present in ionic form, thereby increasing the number of lithium ions that can move freely within the negative electrode film layer, reducing the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increasing the rate of deintercalation and intercalation of lithium ions, and improving the fast-charging performance of the battery cell.

[0347] The first lithium-containing binder and the second lithium-containing binder can be made of the same material or of different materials.

[0348] Optionally, the mass fraction of lithium in the second lithium-containing binder is 3% to 10%, and optionally 3% to 8%. For example, the mass fraction of lithium in the second lithium-containing binder is 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or lies within any two of the values ​​mentioned above. If the mass fraction of lithium is within the range mentioned above, the number of lithium ions freely moving in the negative electrode film layer can be relatively large, further reducing the distance over which the lithium ions diffuse to the surface of the negative electrode film layer, increasing the deintercalation and intercalation rate of the lithium ions, and improving the fast-charging performance of the battery cell.

[0349] For example, the second lithium-containing binder comprises a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 30% to 50%:15% to 45%:5% to 20%:20% to 35%. For example, the molar ratio of lithiuniacrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20% or 40%:20%:10%:30% or 45%:15%:20%:20% etc.

[0350] The lithium-containing binder in the above material can provide a specific amount of lithium ions to the negative electrode film layer, thus improving the fast-charging performance of the battery cell. It does not swell as easily during charging and discharging and exhibits a stable structure, thereby improving the cycle life of the negative electrode film layer during fast charging and discharging.

[0351] In some embodiments, the first negative electrode film layer also comprises a negative electrode binder, and the second negative electrode film layer also comprises a negative electrode binder. The negative electrode binder in the first negative electrode film layer and the negative electrode binder in the second negative electrode film layer each independently comprise at least one of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (for example, polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0352] In some embodiments, the total content of the first lithium-containing binder and the negative electrode binder in the first negative electrode film layer is greater than the total content of the second lithium-containing binder and the negative electrode binder in the second negative electrode film layer, and the mass fraction of the first lithium-containing binder relative to the mass of the first negative electrode film layer is less than the mass fraction of the second lithium-containing binder relative to the mass of the second negative electrode film layer.

[0353] In some embodiments, the negative electrode film layer optionally comprises a conductive element of the negative electrode. The embodiments of the present application do not specifically restrict the type of conductive element of the negative electrode. By way of example, the conductive element of the negative electrode may comprise at least one of superconducting carbon, conductive graphite, carbon black, carbon black, Ketjen carbon black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass fraction of the conductive element of the negative electrode is ≤ 5%, based on the total weight of the negative electrode film layer.

[0354] In some embodiments, the negative electrode film layer optionally also includes a negative electrode binder. In some embodiments, the mass fraction of the negative electrode binder is ≤ 5%, based on the total weight of the negative electrode film layer.

[0355] In some embodiments, the negative electrode film layer optionally comprises further excipients. For example, these excipients may include a thickening agent, a dispersing agent, and the like, such as sodium carboxymethylcellulose (CMC-Na), PTC thermistor material, and the like. In some embodiments, the mass fraction of the excipients, based on the total weight of the negative electrode film layer, is ≤ 2%.

[0356] In some embodiments, the porosity of the negative electrode film layer is 40% to 55%. For example, the porosity of the negative electrode film layer is 40%, 45%, 50%, 55%, or lies in a range consisting of any two of the values ​​mentioned above.

[0357] If the porosity of the negative electrode film layer in the embodiments of the present application is within the above-mentioned range, the migration capability of lithium ions in the negative electrode film layer can be increased and the fast charging performance improved.

[0358] In the embodiments of the present application, the porosity of the negative electrode film layer can be measured using a gas exchange method in accordance with standard GB / T24586. The porosity P = (V1 - V2) / V1 * 100%, where V1 is the apparent volume of the sample and V2 is the actual volume of the sample.

[0359] In some embodiments, the negative electrode current collector section can be a metal foil or a composite current collector section. For example, the metal foil can be made of at least one material: copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. The composite current collector section can comprise a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal material in the metal layer can be copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. For example, the polymer base layer can be polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

[0360] In some embodiments, the thickness of the negative electrode current collector section is 4 µm to 6 µm. For example, the thickness of the negative electrode current collector section is 4 µm, 4.5 µm, 5 µm, 5.5 µm, 6 µm, or lies in a range consisting of any two of the above values.

[0361] If the thickness of the negative electrode current collection section is within the range mentioned above, the negative electrode current collection section exhibits relatively excellent current conductivity and allows for a higher energy density of the battery cell.

[0362] In the embodiments of the present application, the thickness of the negative electrode current collection section has a meaning known in the art and can be determined using devices and methods known in the art, for example by using a solvent to wash off the film layer on the surface of the negative electrode current collection section and by using a high-precision micrometer to measure the thickness of the negative electrode current collection section.

[0363] The negative electrode film layer is typically formed by applying a negative electrode paste to the negative electrode current collector section, followed by drying and cold pressing. The negative electrode paste is usually formed by dispersing and uniformly stirring the negative electrode active, an optional conductive agent, an optional binder, and other optional excipients in a solvent. The solvent may be, but is not limited to, N-methyl-2-pyrrolidone (NMP) or deionized water.

[0364] The negative electrode sheet does not exclude further additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet according to the embodiments of the present application also comprises a conductive layer of the negative electrode, which is enclosed between the negative electrode current collection section and the negative electrode film layer and is arranged on the surface of the negative electrode current collection section. In some other embodiments, the negative electrode sheet according to the embodiments of the present application also comprises a protective layer that covers the surface of the negative electrode film layer.

[0365] In some embodiments, the negative electrode sheet further comprises a conductive layer of the negative electrode, wherein the conductive layer of the negative electrode is located between the negative electrode film layer and the negative electrode current collection section. The conductive layer of the negative electrode can further improve the conductivity of the negative electrode sheet and reduce the heat generation of the negative electrode sheet, thereby reducing the amount of heat generated by the battery cell.

[0366] In some embodiments, the thickness of the conductive layer of the negative electrode is 0.5 µm to 2 µm. For example, the thickness of the conductive layer of the negative electrode can be 0.5 µm, 0.8 µm, 1 µm, 1.2 µm, 1.5 µm, 1.6 µm, 1.8 µm, 2 µm, or a range consisting of any two of the above values.

[0367] If the thickness of the conductive layer of the negative electrode is within the range mentioned above, the conductivity of the negative electrode sheet can be further improved and the heat generation of the negative electrode sheet reduced, thereby reducing the heat generation of the battery cell and simultaneously increasing the energy density of the battery cell.

[0368] In the embodiments of the present application, the thickness of the conductive layer of the negative electrode has a meaning known in the art and can be determined using devices and methods known in the art, and the test method mentioned above for the conductive layer of the negative electrode can be used.

[0369] In some embodiments, the conductive layer of the negative electrode comprises one or more negative electrode conductive elements and negative electrode binders. The conductive element in the negative electrode conductive layer can improve the conductivity of the negative electrode conductive layer, thereby improving the conductivity of the negative electrode sheet and reducing the amount of heat generated by the battery cell. The negative electrode binder in the conductive layer of the negative electrode can improve the bonding performance between the negative electrode current collector section and the negative electrode film layer, thereby increasing the structural stability of the negative electrode sheet.

[0370] In some embodiments, the conductive layer of the negative electrode optionally comprises further excipients. For example, these excipients may include a thickening agent, such as sodium carboxymethylcellulose (CMC), PTC thermistor material, and the like.

[0371] Optionally, the mass fraction of the conductive material of the negative electrode in the conductive layer of the negative electrode is 20% to 40%. For example, the mass fraction of the conductive material of the negative electrode is 20%, 25%, 30%, 35%, 40%, or lies within a range consisting of any two of the values ​​mentioned above.

[0372] For example, the conductive material of the negative electrode comprises one or more of superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen carbon black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0373] Optionally, the mass fraction of the binder in the conductive layer of the negative electrode is 60% to 80%. For example, it is 60%, 65%, 70%, 75%, 80%, or lies within a range consisting of any two of the values ​​mentioned above.

[0374] For example, the binder of the negative electrode comprises one or more of styrene-butadiene rubber SBR, water-soluble unsaturated resin SR-1B, aqueous acrylic resin, polyvinyl alcohol, sodium alginate and carboxymethyl chitosan.

[0375] In some embodiments, the ratio CB of the capacity per unit area of ​​the negative electrode film layer to the capacity per unit area of ​​the positive electrode film layer in the battery cell is 1.05 to 1.30 and optionally 1.07 to 1.15. For example, the ratio CB of the capacity per unit area of ​​the negative electrode film layer to the capacity per unit area of ​​the positive electrode film layer in the battery cell is 1.05, 1.07, 1.1, 1.12, 1.15, 1.18, 1.2, 1.22, 1.25, 1.28, 1.3, or lies in a range consisting of any two of the values ​​mentioned above.

[0376] If the ratio CB of the capacity per unit area of ​​the negative electrode film layer to the capacity per unit area of ​​the positive electrode film layer in the battery cell is within the range mentioned above, there are sufficient sites in the negative electrode film layer for lithium intercalation, which can reduce the risk of lithium plating and promote fast charging.

[0377] In the embodiments of the present application, the CB value has a meaning known in the art and can be determined using devices and methods known in the art. For example, the capacitance of the negative electrode film layer per unit area and the capacitance of the positive electrode film layer per unit area are calculated separately, and the ratio of the two values ​​is calculated to obtain the CB value.

[0378] In particular, it is explained with an upper charging limit voltage of the battery of 3.65 V and a discharge cut-off voltage of the battery of 2.0 V:

[0379] The capacitance of the positive electrode film layer per unit area refers to the actual available delithiation capacitance of the positive electrode active material. The test method is as follows: The battery is disassembled in a Braun glove box PRS340 / 11-119-11, the positive electrode sheet is removed, and reassembled into a CR2430 half-button cell with one positive electrode and one lithium sheet. Assuming that the area of ​​the positive electrode sheet used is a mm² 2The electrolyte solution used is a 1 mol / L LiPF6 solution with an EC / EMC / DEC ratio of 3 / 5 / 2. The assembled half-button cell is left to stand for 3 hours. The tests are performed at 25 °C. The half-button cell is first charged (charged) at 0.1 C in the voltage range of 2.0 V to 3.65 V to deintercalate the lithium, and then discharged (discharged) at 0.05 C to 2.0 V to intercalate the lithium. After two cycles, the discharge capacity of the half-button cell is recorded as Y mAh in the second cycle. Assuming that the positive electrode sheet in the actual battery design has a length of b mm and a width of c mm, and that d areas of the positive electrode current collection section are coated with the positive electrode active material, the capacity of the positive electrode film layer per unit area is then = Y / a*b*c*d.

[0380] Specifically, the capacitance of the negative electrode film layer per unit area refers to the actual available lithiation capacitance of the negative electrode active material. The test method is as follows: The battery is disassembled in a Braun glove box PRS340 / 11-119-11, the negative electrode sheet is removed, and it is reassembled into a CR2430 half-button cell with one negative electrode and one lithium sheet. Assuming that the area of ​​the negative electrode sheet used is f mm² 2The electrolyte solution used is a 1 mol / L LiPF6 solution with an EC / EMC / DEC ratio of 3 / 5 / 2. The assembled half-button cell is left to stand for 3 hours. The tests are performed at 25 °C. The half-button cell is first discharged at 0.1 C in the voltage range of 2 V to 0 V to intercalate the lithium, and then charged at 0.05 C to 2 V to deintercalate the lithium. After two cycles, the discharge capacity of the half-button cell is recorded as Z mAh in the second cycle. Assuming that the negative electrode sheet in the actual battery design has a length of h mm and a width of i mm, and that d areas of the negative electrode current collection section are coated with the negative electrode active material, the capacity of the negative electrode film layer per unit area is then Z / f*h*i*d. [Separator]

[0381] In the embodiments of the present application, the separator comprises a base film with a porous structure.

[0382] In some embodiments, the base film comprises at least one of glass fiber, nonwoven fabric, and polyolefin. The base film can be a single-layer film or a multi-layer composite film without any particular restriction. If the base film is a multi-layer composite film, the materials of each layer can be the same or different without any particular restriction.

[0383] Optionally, the polyolefin comprises at least one of polyethylene, polypropylene and polyvinylidene fluoride.

[0384] In some embodiments, the porosity of the base film is 20% to 70%, optionally 35% to 60%. For example, the porosity of the base film is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or lies within a range consisting of any two of the values ​​mentioned above.

[0385] If the porosity of the base film in the embodiments of the present application is within the above-mentioned range, the migration capability of lithium ions in the separator can be improved and the internal resistance of the battery cell can be further reduced, thereby reducing heat generation.

[0386] In the embodiments of the present application, porosity refers to the percentage of the pore volume relative to the total volume of the separator. The porosity can be tested in accordance with standard GB / T 36363-2018 "Polyolefin separators for battery cells". It should be noted that the actual test process may employ test procedures that deviate from the standard to obtain more accurate measurements, depending on test equipment variations, measurement errors, and the need to minimize the influence of porosity measurements.

[0387] In some embodiments, the thickness of the base film is 6 µm to 12 µm, optionally 6 µm to 9 µm. For example, the thickness of the base film is 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, or lies in a range consisting of any two of the above values.

[0388] If the thickness of the base film is within the range mentioned above, the migration path of the lithium ions in the base film is shorter, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation.

[0389] In the embodiments of the present application, the separator can be a base film. Optionally, the separator additionally comprises a functional layer arranged on at least one side of the base film. The functional layer can comprise inorganic particles to increase the heat resistance of the separator. Optionally, a functional layer is arranged on each side of the base film.

[0390] In some embodiments, the functional layer comprises a first functional layer and a second functional layer, wherein the first functional layer is located on one side of the base film, the first functional layer comprises first inorganic particles, the second functional layer is located on the other side of the base film, and the second functional layer comprises composite particles, wherein the composite particles comprise second inorganic particles and several non-fluoropolymer particles, wherein the second inorganic particles adhere to the surface of the non-fluoropolymer particles and / or are dispersed inside the non-fluoropolymer particles.

[0391] The first functional layer and the second functional layer exhibit good heat resistance and can increase the heat resistance of the separator.

[0392] Optionally, the first functional layer may include a binder, optionally at least one of a fluorine-containing binder or a polyacrylic binder, such as polyvinylidene fluoride.

[0393] Optionally, the first inorganic particles include one or more of silicon dioxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium dioxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These initial inorganic particles can increase the heat resistance of the first functional layer.

[0394] In the embodiments of the present application, the thickness of the base film has a meaning known in the art and can be determined using means and devices known in the art. For example, a freshly manufactured separator can be taken as a sample, or a fully discharged battery cell (discharged to the lower limit voltage, so that the battery's state of charge is approximately 0% SOC) can be reverse disassembled and the separator removed. The separator is dried and used as a sample. Subsequently, the separator is cut with an ion beam cutter to produce a cross-section. The thickness of the separator cross-section and its various layers is then measured using a scanning electron microscope.

[0395] The non-fluorinated polymer particles in the second functional layer are non-fluorinated polymers. For example, the non-fluorinated polymer particles comprise an acrylate copolymer. Optionally, the acrylate copolymer comprises an acrylate-acrylonitrile-acrylamide-propylene copolymer. The acrylate copolymer is characterized by excellent bonding performance and high bond stability with the base film. The molar ratio of the individual monomers in the copolymer can be any desired ratio, for example, 35%:30%:15%:20%, 40%:20%:10%:30%, 45%:15%:20%:20%, etc.

[0396] Within the composite particles, the second set of inorganic particles prevents the non-fluoropolymer particles from bonding during the high-temperature granulation process. This creates pores in the composite particles that promote lithium ion transport and improve the separator's ion conductivity. Additionally, these second set of inorganic particles increase the bulk modulus of the composite particles, making them less prone to deformation during charging and discharging. This stabilizes the separator's structure, improves the battery cell's kinetic performance, and enhances fast-charging capabilities. Optionally, the second functional layer is positioned closer to the negative electrode sheet than the first.Since the composite particles do not deform easily, the separator generally does not cause any side effects such as pressure on the negative electrode sheet, so the kinetic performance of the negative electrode sheet remains stable. Accordingly, the first functional layer is located close to the positive electrode sheet.

[0397] Optionally, the second inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. Silicon oxide is also optionally included. These second inorganic particles can enhance the heat resistance of the second functional layer and, together with non-fluorinated polymers, form composite particles to further improve the separator's cycle stability and kinetic performance, thereby enhancing the battery cell's cycle life and fast-charging performance.

[0398] The average particle size of the second inorganic particle is 5 nm to 100 nm, optionally 10 nm to 100 nm, and optionally 5 nm to 20 nm. For example, the average particle size of the second inorganic particle could be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or a range consisting of any two of the above values. Having the average particle size of the second inorganic particle within the above range is advantageous for increasing the heat resistance and bulk modulus of the composite particles.

[0399] In the embodiments of the present application, the average particle size of the second inorganic particles has a meaning known in the art and can be determined using devices and methods known in the art. For example, after receiving the separator, it is dried and used as a sample. Subsequently, the separator is cut with an ion beam cutter to produce a cross-section. The particle size of the second inorganic particles in the separator is then measured with a scanning electron microscope. The particle sizes of several, for example 50, second inorganic particles are measured, and the average value is calculated as the average particle size of the second inorganic particles.

[0400] In some embodiments, the ionic conductivity of the separator is 0.3 mS / cm to 0.6 mS / cm. For example, the ionic conductivity of the separator is 0.3 mS / cm, 0.35 mS / cm, 0.4 mS / cm, 0.45 mS / cm, 0.5 mS / cm, 0.55 mS / cm, 0.6 mS / cm, or lies within a range consisting of any two of the above values.

[0401] If the ionic conductivity of the separator is within the range mentioned above, the migration capability of the lithium ions in the separator can be further improved, thereby improving the fast charging performance of the battery cell.

[0402] In the embodiments of the present application, the ionic conductivity of the separator has a meaning known in the art and can be determined using devices and methods known in the art, for example:

[0403] Production of a 2025 button cell for testing purposes: A lithium sheet is placed in a negative electrode casing of the battery within a vacuum glove box. 150 µL of electrolyte solution is added. The electrolyte solution used is a 1 mol / L LiPF6 solution with an EC / EMC / DEC ratio of 3 / 5 / 2 (mass ratio). A separator (with an area of ​​3.14 cm²) is then used. 2 and a thickness of 12 µm) is placed on the lithium sheet. A further 25 µL of electrolyte solution is added. Finally, a positive electrode sheet (the positive electrode sheet can be the one from embodiment 1) is placed on top before the cell is encapsulated. The assembled button cell is removed from the vacuum glove box and stored for 24 hours to prepare for subsequent tests.

[0404] Test: At an electrochemical workstation, measurements are taken in the frequency range of 10 -1 up to 10 6Hz measured to measure a separator resistor R b to determine. The ionic conductivity σ (unit: mS / cm) is calculated using the following formula: σ=L / (Rb×S) where R b L represents the resistance of the separator, while L denotes the thickness and S the area of ​​the separator to be tested. [Electrolyte solution]

[0405] In some embodiments, the battery cell also includes an electrolyte solution.

[0406] During the charging and discharging process of the battery cell, the active ions migrate between the positive and negative electrode sheets for intercalation and deintercalation, with the electrolyte solution having the function of guiding the active ions between the positive and negative electrode sheets.

[0407] In the embodiments of the present application, the conductivity of the electrolyte solution is 13 mS / cm to 20 mS / cm, optionally 15 mS / cm to 20 mS / cm. By way of example, the conductivity of the electrolyte solution at room temperature is 13 mS / cm, 13.5 mS / cm, 14 mS / cm, 14.5 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 16.5 mS / cm, 17 mS / cm, 17.5 mS / cm, 18 mS / cm, 18.5 mS / cm, 19 mS / cm, 19.5 mS / cm or 20 mS / cm, or lies in a range consisting of any two of the above values.

[0408] If the conductivity of the electrolyte solution at room temperature, for example 25 °C, is within the range mentioned above, the migration rate of lithium ions in the electrolyte solution is relatively high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0409] In the embodiments of the present application, the conductivity of the electrolyte solution at room temperature, for example 25 °C, is the ionic conductivity, which can be determined using devices and methods known in the art, for example by tests with reference to the industry standard HG-T 4067-2015.

[0410] In some embodiments, the viscosity of the electrolyte solution at room temperature is between 2.3 mPa·s and 3.5 mPa·s. For example, the viscosity of the electrolyte solution is 2.3 mPa·s, 2.4 mPa·s, 2.5 mPa·s, 2.6 mPa·s, 2.7 mPa·s, 2.8 mPa·s, 2.9 mPa·s, 3.0 mPa·s, 3.1 mPa·s, 3.2 mPa·s, 3.3 mPa·s, 3.4 mPa·s, 3.5 mPa·s, or lies within a range consisting of any two of the values ​​mentioned above.

[0411] If the viscosity of the electrolyte solution at room temperature, for example 25 °C, is within the range mentioned above, the migration rate of lithium ions in the electrolyte solution is relatively high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and thus improving the fast charging performance of the battery cell.

[0412] In the embodiments of the present application, the viscosity of the electrolyte solution has a meaning known in the art and can be determined using devices and methods known in the art. For example, it can be determined according to GB / T10247-2008.

[0413] In some embodiments, the density of the electrolyte solution at room temperature, for example 25 °C, is 1.05 g / mL to 1.35 g / mL. For example, the density of the electrolyte solution is 1.05 g / mL, 1.10 g / mL, 1.15 g / mL, 1.2 g / mL, 1.25 g / mL, 1.3 g / mL, 1.35 g / mL, or lies within a range consisting of any two of the above values.

[0414] If the density of the electrolyte solution is within the range mentioned above, the migration rate of lithium ions in the electrolyte solution is relatively high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and thus improving the fast charging performance of the battery cell.

[0415] In the embodiments of the present application, the density of the electrolyte solution has a meaning known in the art and can be determined using devices and methods known in the art, for example by reference to GB / T 2013-2010 for testing.

[0416] The electrolyte solution comprises an organic solvent and an electrolyte salt. There are no particular restrictions on the types of organic solvents and electrolyte salts used, and they can be selected according to the actual requirements.

[0417] In some embodiments, the organic solvent comprises a chain-like carboxylic ester solvent, and the mass fraction of the chain-like carboxylic ester solvent, relative to the mass of the organic solvent, is greater than or equal to 5% and less than or equal to 75%, optionally greater than or equal to 10% and less than or equal to 75%, optionally 30% to 75%. For example, the mass fraction of the chain-like carboxylic ester solvent is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or 75%, or lies within a range consisting of any two of the above values.

[0418] If the mass fraction of the chain-like carboxylic acid ester solvent is within the range mentioned above, the viscosity of the electrolyte solution system is relatively low, which has a positive effect on the migration of lithium ions.

[0419] If the mass fraction of the chain-like carboxylic acid ester solvent is within the range mentioned above, the viscosity of the electrolyte solution system is relatively low, which has a positive effect on the migration of lithium ions.

[0420] In some embodiments, the chain-like carboxylic acid ester solvent comprises a compound represented by formula I, where in Formula I, R1 comprises a hydrogen atom, a halogen atom, a C1 to C5 alkyl group, or a halogenated C1 to C5 alkyl group. R2 comprises a C1 to C5 alkyl group or a halogenated C1 to C5 alkyl group.

[0421] The aforementioned chain-like carboxylic acid ester solvent exhibits high conductivity, which has a positive effect on improving the fast-charging capability of the battery cell.

[0422] Optionally, R1 comprises a hydrogen atom, a halogen atom, a C1 to C3 alkyl group, or a halogenated C1 to C3 alkyl group. Furthermore, optionally, R1 comprises a hydrogen atom, a halogen atom, a C1 to C2 alkyl group, or a halogenated C1 to C2 alkyl group.

[0423] Optionally, R2 comprises a C1 to C3 alkyl group or a halogenated C1 to C3 alkyl group. Furthermore, optionally, R2 comprises a C1 to C2 alkyl group or a halogenated C1 to C2 alkyl group.

[0424] In the embodiments described above, the halogen atom comprises one or more fluorine, chlorine, bromine, and iodine atoms. Optionally, the halogen atom comprises a fluorine atom.

[0425] In the above embodiments, the haloalkyl group comprises one or more fluoroalkyl groups, chloroalkyl groups, bromoalkyl groups, and iodoalkyl groups. Optionally, the haloalkyl group comprises a fluoroalkyl group.

[0426] For example, the chain-like carboxylic acid ester solvent comprises one or more of the compounds represented by formulas I-1 to I-8,

[0427] In some embodiments, the organic solvent also comprises a carbonate solvent.

[0428] Optionally, the carbonate solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The aforementioned carbonate solvent and chain-like carboxylic acid ester solvents are used together to improve the conductivity of the electrolyte solution, which has a positive effect on the migration of lithium ions.

[0429] Optionally, the mass fraction of the carbonate solvent in the organic solvent can be 25% to 95%, or optionally 25% to 70%. For example, the mass fraction of the carbonate solvent in the organic solvent can be 25%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or a range consisting of any two of the values ​​mentioned above. The carbonate solvent with the mass fraction mentioned above can further improve the conductivity of the electrolyte solution at room temperature, which has a positive effect on the migration of lithium ions.

[0430] For example, the carbonate solvent comprises one or more of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, wherein the mass fraction of the carbonate solvent is 30% to 50%.

[0431] In some embodiments, the electrolyte solution also contains an additive, which may include a film-forming additive for the negative electrode, a film-forming additive for the positive electrode, and an additive that can improve certain battery performance characteristics, such as an additive that improves the battery's overcharge behavior, an additive that improves the battery's high-temperature performance, and an additive that improves the battery's low-temperature performance.

[0432] In some embodiments, the additive contains one or more carbonate additives, sulfur-containing additives, and lithium salt additives, and optionally at least two of these. The aforementioned additive can improve the performance of the interfacial films on the positive electrode side and / or the negative electrode side, which has a positive effect on improving the fast-charging performance of the battery cell and its cycle life.

[0433] In some embodiments, the mass fraction of the additive in the electrolyte solution is 1% to 10%, optionally 2% to 8%, and further optionally 3.5% to 8%. For example, the mass fraction of the additive in the electrolyte solution is 1%, 2%, 3%, 3.5%; 4%, 5%, 6%, 7%, 8%, 9%, 10%, or lies within a range consisting of any two of the above values.

[0434] The additive with the above-mentioned mass fraction can effectively improve the performance of the interfacial films on the positive electrode side and / or the negative electrode side, which has a positive effect on improving the fast charging performance of the battery cell and the cycle performance.

[0435] For example, the carbonate additive comprises one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0436] For example, the sulfur-containing additive includes one or more of ethylene sulfate DTD, bis(ethylene sulfate) 2-DTD, butylene sulfite BS, 1,3-propanesultone PS, ethylene sulfite ES and methylenemethanedisulfonate MMDS.

[0437] Optionally, the lithium salt additive includes one or more of lithium difluorophosphate LiPO2F2, lithium difluoro(oxalato)borate LiDFOB, lithium tetrafluoroborate LiBF4, lithium bis(oxalato)borate LiBOB.

[0438] Optionally, the mass fraction of vinylene carbonate (VC) in the electrolyte solution is 0.5% to 9%, optionally 2% to 6%.

[0439] Optionally, the mass fraction of fluoroethylene carbonate (FEC) in the electrolyte solution is 0.1% to 4%, optionally 0.5% to 3%.

[0440] Optionally, the mass fraction of vinylene carbonate VC in the electrolyte solution is 0.5% to 9% and the mass fraction of fluoroethylene carbonate FEC in the electrolyte solution is 0.1% to 4%.

[0441] Optionally, the mass fraction of vinylene carbonate VC in the electrolyte solution is 2% to 6% and the mass fraction of fluoroethylene carbonate FEC in the electrolyte solution is 0.5% to 3%.

[0442] In some embodiments, the electrolyte salt comprises a lithium salt, and the lithium salt comprises one or more fluorinated sulfonylimide salts and lithium hexafluorophosphate (LiPF6). The aforementioned lithium salt is readily dissociated, which promotes the rapid migration of lithium ions. Furthermore, the electrolyte solution system is relatively stable and does not decompose easily, which can improve the cycle life of the battery cell.

[0443] Optionally, the fluorine-containing sulfonylimide salt comprises one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0444] Optionally, the lithium salt comprises lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. The molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L.

[0445] For example, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.4 mol / L to 0.5 mol / L and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.7 mol / L.

[0446] For example, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.5 mol / L and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L.

[0447] For example, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.8 mol / L.

[0448] Optionally, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate LiPF6 is 0.2 to 1.0, optionally 0.2 to 0.5. For example, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate LiPF6 is 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or lies within a range consisting of any two of the values ​​mentioned above.

[0449] In the embodiments of the present application, the type and concentration of the inorganic components / lithium salts in the electrolyte solution have meanings known in the art and can be determined using devices and methods known in the art. For example, the inorganic components / lithium salts in the electrolyte solution can be analyzed qualitatively or quantitatively by ion chromatography in accordance with the standard JY / T020-1996 "General rules for ion chromatography analysis methods".In the embodiments of the present application, a newly prepared electrolyte solution can be taken as a sample, a free electrolyte solution from a fresh battery can be taken as a sample, or a completely discharged battery (it has been discharged to the discharge cut-off voltage, so that the state of charge of the battery is approximately 0% SOC) can be reverse disassembled and the free electrolyte solution obtained from the battery taken as a sample. The sample is analyzed using the ion chromatography analytical method.

[0450] In the embodiments of the present application, the type and content of the organic components in the electrolyte solution have meanings known in the art and can be determined using devices and methods known in the art. For example, reference can be made to GB / T9722-2006 "General rules for the gas chromatography of chemical reagents" to carry out a qualitative and quantitative analysis of organic components in the electrolyte solution by means of gas chromatography.In the embodiments of the present application, a newly prepared electrolyte solution can be taken as a sample, a free electrolyte solution from a fresh battery can be taken as a sample, or a completely discharged battery (it has been discharged to the discharge cut-off voltage, so that the state of charge of the battery is approximately 0% SOC) can be reverse disassembled and the free electrolyte solution obtained from the battery taken as a sample. The sample is analyzed using the ion chromatography analytical method.

[0451] In the embodiments of the present application, the components are classified after quantitative and qualitative analysis of all components in the electrolyte solution. The chain-like carboxylic acid ester solvents and carbonate solvents (such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate) are classified as constituents of the organic solvent. The mass fraction of the individual components is calculated relative to the mass of the organic solvent, based on 100%.

[0452] The carbonate additive (such as vinylene carbonate, fluoroethylene carbonate), the sulfur-containing additive, and the lithium salt additive are classified as additives to the electrolyte solution. The mass fraction of each component is calculated based on the mass of the electrolyte solution at 100%.

[0453] In some embodiments, the battery cell meets the following condition: d / A ≤ 3.5 g / Ah, optionally 2.40 g / Ah ≤ d / A ≤ 3.3 g / Ah, where d represents the mass of the electrolyte solution in the battery cell in g and A represents the nominal capacity of the battery cell in Ah. For example, d / A can be 3.5 g / Ah, 3.3 g / Ah, 3.2 g / Ah, 3.0 g / Ah, 2.8 g / Ah, 2.5 g / Ah, 2.45 g / Ah, 2.4 g / Ah, or within a range consisting of any two of the above values.

[0454] d / A can reflect the liquid retention capacity of the electrolyte solution. If d / A is within the range mentioned above, the electrolyte solution can better wet the positive and negative electrode sheets and increase the migration rate of lithium ions in the liquid phase, which has a positive effect on the fast-charging capability of the battery cell.

[0455] In the embodiments of the present application, d / A of the battery cell is understood to be the liquid retention coefficient, which can be determined using devices and methods known in the art. For example, according to GB / T3 1486-2015 "Electrical performance requirements and test methods for traction batteries for electric vehicles" with an upper charging voltage of 3.65 V and a discharge cut-off voltage of 2.0 V, the following can be explained:

[0456] The battery cell is charged at 25 °C at 0.33 C to 3.65 V, then further charged at a constant voltage to 0.05 C. It is then discharged at a constant current of 0.33 C to 2.0 V. The discharged capacity A is used as the denominator. The battery cell is weighed as M0. The positive electrode, the negative electrode, the separator, and the electrolyte solution are disassembled, with the free electrolyte solution collected in a bag. All solid components (including, but not limited to, the positive and negative electrodes, the separator, and other mechanical components of the disassembled battery cell that contribute to M0) are dried in a drying box at 60 °C for over 4 hours. Subsequently, all components of the battery cell are weighed as M1. The difference between M0 and M1 is used as the counter.The fluid retention coefficient is equal to the value obtained by dividing the weight difference d between M0 and M1 by the capacity A.

[0457] As in Fig. As shown in Figure 10, in some embodiments of the present application, the battery cells 7 can be assembled into a battery module 6 according to the embodiments of the present application. The number of battery cells 7 contained in the battery module 6 can be one or more, and the exact number can be adapted depending on the application and capacity of the battery module 6.

[0458] If multiple battery cells 7 are present, they can be connected in series, parallel, or in a mixed circuit, where a mixed circuit means that both series and parallel connections exist between the multiple battery cells 7. The multiple battery cells 7 can be connected directly in series, parallel, or in a mixed circuit, and the resulting assembly can then be accommodated in a receiving section of the battery module 6. Alternatively, the multiple battery cells 7 can first be connected in series, parallel, or in a mixed circuit to form a battery module 6, and multiple battery modules 6 can then be further connected in series, parallel, or in a mixed circuit to form a complete assembly and accommodated in the receiving section.Optionally, the battery module 6 can also include a recording section with a recording space, and the multiple battery cells 7 are recorded in the recording space.

[0459] As in Fig. As shown in Figure 11, in some embodiments the aforementioned battery modules 6 can also be assembled into a battery pack 2. The number of battery modules 6 contained in the battery pack 2 can be adjusted depending on the application and capacity of the battery pack. The battery device can be either a single battery module 6 or a battery pack 2.

[0460] The battery pack 2 can comprise a housing 5 and several battery modules 6 arranged within the housing 5. The housing 5 comprises a first housing section 5a and a second housing section 5b. The housing 5 has a receiving space 5c. The first housing section 5a serves to cover the second housing section 5b and form an enclosed space for receiving the battery module 6. The multiple battery modules 6 can be arranged within the housing 5 in any configuration.

[0461] The first box body section 5a and the second box body section 5b overlap each other, and together they define a receiving space 5c for the battery cell. The second box body section 5b can have a hollow structure with one open side. The first box body section 5a has a plate-like structure. The first box body section 5a covers the open side of the second box body section 5b, thus forming the box body 5 with the receiving space 5c. Alternatively, the first box body section 5a and the second box body section 5b can each have a hollow structure with one open side. The open side of the first box body section 5a covers the open side of the second box body section 5b, thus forming the box body 5 with the receiving space 5c.Of course, the first box body section 5a and the second box body section 5b can have different shapes, for example the shape of a cylinder, a cuboid and the like.

[0462] To increase the tightness of the connection between the first box body section 5a and the second box body section 5b, a sealing element, such as a sealant, a sealing ring, etc., can also be provided between the first box body section 5a and the second box body section 5b.

[0463] Assuming that the first box body section 5a covers the top of the second box body section 5b, the first box body section 5a can also be referred to as the upper box cover and the second box body section 5b as the lower box body.

[0464] In some embodiments, the temperature of the external environment in which the battery pack 2 is located during the operation of the battery pack 2 or any battery cell of which the battery pack 2 consists, changes from the state of charge (SOC) of 0% to 100% room temperature, for example 30°C.

[0465] In some embodiments, the temperature of the external environment in which the battery pack 2 is located during the operation of the battery pack 2 or any battery cell of which the battery pack 2 consists, changes from the state of charge (SOC) of 20% to 80% room temperature, for example 30°C.

[0466] In some embodiments, the charging process of battery pack 2, or of any battery cell comprising battery pack 2, from a state of charge of 20% to 80% comprises several charging steps. The difference between the maximum state of charge of any one charging step within these multiple charging steps and the maximum state of charge in the adjacent charging step is less than or equal to the state of charge of 5%, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, or lies within a range consisting of any two of the aforementioned values.

[0467] The charging process of battery pack 2, or of any individual battery cell comprising battery pack 2, from a state of charge of 20% to 40%, involves several charging steps. Each charging step can be performed at any charging rate between 5C and 10C. The charging rate for each step can be any value from 5C, 5.5C, 6C, 6.5C, 7C, 7.5C, 8C, 8.5C, 9C, 9.5C, or 10C, or any combination of these two values.

[0468] For example, the charging step of the charging process of battery pack 2 or any battery cell of which battery pack 2 consists, from 20% to 80%, can be carried out as follows:

[0469] With a constant current of 5.0 C, charging from 20% SOC to 25% SOC is achieved; With a constant current of 5.0 C, charging from 25% SOC to 30% SOC is achieved; With a constant current of 5.0 C, charging from 30% SOC to 35% SOC is achieved; With a constant current of 5.0 C, charging from 35% SOC to 40% SOC is achieved; With a constant current of 4.6 C, it charges from 40% SOC to 45% SOC; With a constant current of 4.3 C, it charges from 45% SOC to 50% SOC; Charging with a constant current of 4.0 C from 50% SOC to 55% SOC; With a constant current of 3.7 C, it charges from 55% SOC to 60% SOC; With a constant current of 3.4 C, it charges from 60% SOC to 65% SOC; With a constant current of 3.1 C, it charges from 65% SOC to 70% SOC; With a constant current of 2.9 C, it charges from 70% SOC to 75% SOC; With a constant current of 2.7 C, the battery is charged from 75% SOC to 80% SOC.

[0470] In some embodiments, the charging time of the battery pack 2, or of any battery cell comprising the battery pack 2, from a state of charge of 20% to 80% is less than or equal to 15 minutes, optionally ranging from 6 minutes to 15 minutes. The ambient temperature of the battery pack 2 at a state of charge of 20% is room temperature, for example, 30 °C. For example, the charging time of the battery pack 2 from a state of charge of 20% to 80% may be 15 minutes, 14.5 minutes, 14 minutes, 13.5 minutes, 13 minutes, 12.5 minutes, 12 minutes, 11.5 minutes, 11 minutes, 10.5 minutes, 10 minutes, 9.5 minutes, 9 minutes, 8.5 minutes, 8 minutes, 7.5 minutes, 7 minutes, 6.5 minutes, 6 minutes, or a range consisting of any two of the above values.

[0471] In some embodiments, the volumetric energy density of the battery cell is 390 Wh / L to 500 Wh / L and optionally 410 Wh / L to 470 Wh / L. For example, the volumetric energy density of the battery cell is 390 Wh / L, 400 Wh / L, 410 Wh / L, 420 Wh / L, 430 Wh / L, 440 Wh / L, 450 Wh / L, 460 Wh / L, 470 Wh / L, 480 Wh / L, 490 Wh / L, 500 Wh / L, or lies within a range consisting of any two of the above values. The volumetric energy density of the battery cell is higher.

[0472] In the embodiments of the present application, the volume energy density of the battery cell has a meaning known in the art and can be determined using devices and methods known in the art. For example, with an upper charging limit voltage of the battery of 3.65 V and a discharge cut-off voltage of the battery of 2.0 V, the following is explained:

[0473] The battery cell is charged at 25 °C with a constant current of 0.33 C to 3.65 V, then charged with a constant voltage to 0.05 C, and finally discharged with a constant current of 0.33 C to 2.0 V. The discharge capacity A0 is recorded at this point in Ah. The length, width, and height of the battery cell are measured using calipers (usually based on the battery casing size, excluding the height of the electrode terminals and the insulating film outside the casing). The volume V0 of each battery is calculated in L. The volumetric energy density of the battery cell VED = (A0 × discharge platform voltage) / V0 in Wh / L. Power-consuming device

[0474] In a second aspect of the embodiments of the present application, a power-consuming device is provided, comprising a battery cell, a battery module, and / or a battery pack according to the embodiments of the present application. The battery cell, battery module, or battery pack can be used as a power source for the power-consuming device or as an energy storage device for the power-consuming device. The power-consuming devices can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. The vehicle can be a fuel-powered vehicle, a gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or a range-extender vehicle, etc. The spacecraft includes an aircraft, a rocket, a space transporter, and a spacecraft, etc.The term "electric toy" includes stationary or mobile electric toys such as a game console, an electric toy car, an electric toy ship, and an electric toy airplane, etc. The term "electric tool" includes metal cutting tools, grinding tools, assembly tools, and railway tools, for example, an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, a hammer drill, a concrete vibrator, and an electric planer, etc. The embodiments of the present application do not constitute any particular restrictions on the aforementioned power-consuming devices.

[0475] The power-consuming device can be equipped with a battery cell, a battery module or a battery pack, depending on its usage requirements.

[0476] Fig.Figure 12 is a schematic representation of a power-consuming device 1 as an example. The power-consuming device 1 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the power-consuming device 1's requirements for high power and high energy density, a battery pack or battery module can be used.

[0477] Inside the power-consuming device 1, a battery pack 2 is arranged. The battery pack 2 can be located at the bottom, top, or rear of the power-consuming device 1. The battery pack 2 can be used to supply power to the power-consuming device 1. For example, the battery pack 2 can be used as an operating power source for the power-consuming device 1 and also as a drive power source for the power-consuming device 1, replacing fuel or natural gas wholly or partially to provide the drive for the power-consuming device 1.

[0478] The power-consuming device 1 can further comprise a controller 3 and a motor 4, wherein the controller 3 is used to control the battery pack 2 to supply power to the motor 4, for example to meet the work power requirements of the power-consuming device 1 when starting, navigating and driving.

[0479] Another example of a power-consuming device could be a mobile phone, a tablet, a laptop, etc. The power-consuming device typically needs to be lightweight and thin, and a battery cell can be used as its power source.

[0480] The following charging methods are available for charging the power-consuming device:

[0481] With a constant current of 5.0 C, charging from 20% SOC to 25% SOC is achieved; With a constant current of 5.0 C, charging from 25% SOC to 30% SOC is achieved; With a constant current of 5.0 C, charging from 30% SOC to 35% SOC is achieved; With a constant current of 5.0 C, charging from 35% SOC to 40% SOC is achieved; With a constant current of 4.6 C, it charges from 40% SOC to 45% SOC; With a constant current of 4.3 C, it charges from 45% SOC to 50% SOC; Charging with a constant current of 4.0 C from 50% SOC to 55% SOC; With a constant current of 3.7 C, it charges from 55% SOC to 60% SOC; With a constant current of 3.4 C, it charges from 60% SOC to 65% SOC; With a constant current of 3.1 C, it charges from 65% SOC to 70% SOC; With a constant current of 2.9 C, it charges from 70% SOC to 75% SOC; With a constant current of 2.7 C, the battery is charged from 75% SOC to 80% SOC.

[0482] In some embodiments, the charging time of the power-consuming device from a state of charge of 20% to 80% is less than or equal to 15 minutes, optionally from 6 minutes to 15 minutes. The temperature of the external environment of the battery pack 2 in the power-consuming device at a state of charge of 20% is room temperature, for example, 30 °C. For example, the charging time of the battery pack 2 in the power-consuming device from a state of charge of 20% to 80% is 15 minutes, 14.5 minutes, 14 minutes, 13.5 minutes, 13 minutes, 12.5 minutes, 12 minutes, 11.5 minutes, 11 minutes, 10.5 minutes, 10 minutes, 9.5 minutes, 9 minutes, 8.5 minutes, 8 minutes, 7.5 minutes, 7 minutes, 6.5 minutes, 6 minutes, or lies within a range consisting of any two of the above values. Example of implementation

[0483] The following exemplary embodiments describe in more detail the content disclosed in the embodiments of the present application. These exemplary embodiments serve only as an illustration, since various modifications and changes within the scope of the content disclosed in the embodiments of the present application are obvious to the person skilled in the art. Unless otherwise stated, all proportions, percentages, and ratios given in the following exemplary embodiments refer to mass. All reagents used in the exemplary embodiments are commercially available or are synthesized by conventional methods and can be used directly without further treatment. The instruments used in the exemplary embodiments are commercially available. Example 11. Production of the positive electrode sheet

[0484] The positive electrode sheet comprised a positive electrode current collection section, a conductive layer of the positive electrode, and a positive electrode film layer on the positive electrode current collection section, and the positive electrode current collection section was a 10 µm thick aluminum foil.

[0485] The conductive layer of the positive electrode on the positive electrode current collection section was a 1 µm thick film layer formed by uniformly mixing the conductive medium of the positive electrode made of superconducting carbon, the binder of the positive electrode made of polyvinylidene fluoride (PVDF) and the solvent made of N-methyl-2-pyrrolidone NMP, applying the mixture to the surface of the current collection section and drying, wherein in the conductive layer of the positive electrode the mass fraction of the conductive medium of the positive electrode was 40% and that of the binder of the positive electrode was 60%.

[0486] The positive electrode film layer comprised a film layer formed by uniformly applying the positive electrode paste (solvent: N-methyl-2-pyrrolidone, NMP) to the surface of the conductive layer of the positive electrode, drying, and cold pressing. The positive electrode film layer comprised a positive electrode active material, a binder (polyvinylidene fluoride, PVDF), and a conductive agent (acetylene carbon black) in a weight ratio of 97:2:1.

[0487] The positive electrode active material comprised lithium iron phosphate and a coating layer, the surface of which was coated with the coating layer, and the coating layer comprising lithium iron titanium phosphate (Li₂FeTi(PO₄)₃) and amorphous carbon. The Dv₅₀ value of the positive electrode active material was 1.6 µm and the Dv₁₀ value was 0.64 µm. The particle size of the smallest particle was 0.2 µm and the particle size of the largest particle was 18 µm.

[0488] The one-sided coating weight of the positive electrode film layer was 240 mg / 1540.25 mm². 2 . 2. Production of the negative electrode sheet

[0489] The negative electrode sheet comprised a negative electrode current collection section, a conductive layer of the negative electrode, and a negative electron film layer on the negative electrode current collection section, and the negative electrode current collection section was a 5 µm thick copper foil.

[0490] The conductive layer of the negative electrode on the negative electrode current collector section was a 1 µm thick electrode film layer formed by uniformly mixing the conductive agent of the negative electrode made of superconducting carbon, the binder of the negative electrode made of styrene-butadiene rubber (SBR), the thickener made of sodium carboxymethylcellulose (CMC-Na), and the solvent made of water, applying the mixture to the surface of the negative electrode current collector section, and drying, wherein the mass fraction of the conductive agent of the negative electrode in the conductive layer of the negative electrode was 35%, the mass fraction of the binder of the negative electrode in the conductive layer of the negative electrode was 60%, and the mass fraction of the thickener in the conductive layer of the negative electrode was 5%.

[0491] The negative electrode film layer comprised a film layer formed by uniformly applying the negative electrode paste (solvent: deionized water) to the surface of the conductive layer of the negative electrode, followed by drying and cold pressing.

[0492] The one-sided coating weight of the negative electrode film layer was 110 mg / 1540.25 mm². 2 .

[0493] The negative electrode film layer comprised a first negative electrode film layer and a second negative electrode film layer, wherein the first negative electrode film layer was located on the surface of the conductive layer of the negative electrode and the second negative electrode film layer was located on the surface of the first negative electrode film layer.

[0494] The first negative electrode film layer comprised graphite particles, a conductive agent made of acetylene carbon black, a first lithium-containing binder (a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer was 35%:30%:15%:20%), a negative electrode binder made of styrene-butadiene rubber and a thickening agent made of sodium carboxymethylcellulose with a mass ratio of 96.5:0.5:0.5:1.5:1. The mass fraction of the element lithium in the first lithium-containing binder was 4.8%, the Dv50 value of the graphite particles was 11.3 µm, the graphite particles comprised artificial graphite and a carbon coating layer, the surface of the artificial graphite was coated with the carbon coating layer, and the mass fraction of the carbon coating layer was 3.5%.

[0495] The second negative electrode film layer comprised graphite particles, a conductive agent made of acetylene carbon black, a second lithium-containing binder (a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer was 35%:30%:15%:20%), a negative electrode binder made of styrene-butadiene rubber and a thickening agent made of sodium carboxymethylcellulose with a mass ratio of 97.5:0.5:0.5:0.5:1. The mass fraction of the element lithium in the second lithium-containing binder was 4.8%, the Dv50 value of the graphite particles was 11.3 µm, the graphite particles comprised artificial graphite and a carbon coating layer, the surface of the artificial graphite was coated with the carbon coating layer, and the mass fraction of the carbon coating layer was 3.5%. 3. Separator

[0496] The separator comprised a base film, the base film being a 7 µm thick polyethylene film layer with a porosity of 42%. 4. Preparation of the electrolyte solution

[0497] The electrolyte solution comprised an organic solvent, a lithium salt, and an additive.

[0498] The organic solvent comprised 60% chain-like carboxylic acid ester solvent (ethyl acetate) and 40% carbonate solvent (30% ethylene carbonate EC, 10% dimethyl carbonate), with the mass fractions of the individual components in the organic solvent being calculated based on the mass of the organic solvent.

[0499] Based on the mass of the electrolyte solution, the mass fraction of the additive was 6.5%, comprising vinylene carbonate VC, fluoroethylene carbonate FEC, ethylene sulfite ES and lithium difluoro(oxalato)borate LiDFOB in a mass ratio of 5:0.5:0.5:0.5.

[0500] The lithium salt comprised 1 mol / L lithium hexafluorophosphate LiPF6.

[0501] The conductivity of the electrolyte solution at room temperature was 16.4 mS / cm. 5. Manufacturing the battery cell

[0502] The positive electrode sheet, the separator, and the negative electrode sheet were stacked sequentially. The separator was positioned between the positive and negative electrode sheets to provide insulation, thus forming an electrode assembly. The electrode assembly was placed in an outer packaging sleeve. After drying, the electrolyte solution was injected, and a battery cell was obtained by vacuum sealing, standing, formation, and shaping, etc. The compaction density of the positive electrode film layer at 100% state of charge (SOC) of the battery cell was 2.65 g / cm³. 3 was, and the density of the negative electrode film layer at 100% SOC was 1.26 g / cm³ 3fraud. Comparison example 1 and comparison example 2

[0503] The battery cell was manufactured using a similar process to that described in embodiment 1. The difference compared to embodiment 1 was that the width and length of the positive electrode film layer were adjusted. Exemplary embodiment 2-1 and Exemplary embodiment 2-2

[0504] The battery cell was manufactured using a similar process to that described in embodiment 1. The difference compared to embodiment 1 was that the width of the positive electrode film layer was adjusted. Performance tests: 1. Test of the DC internal resistance (DCR) of the battery cell

[0505] Reference can be made to the methods in GB / T 31467 “Test specification for high-performance lithium-ion traction batteries for HEV”.

[0506] For example, the battery cell was charged at -20 °C with a constant current of 0.33 C to 3.65 V and left at rest for 1 minute; then it was charged with a constant current of 0.1 C to 3.65 V and left at rest for 30 minutes. The battery cell was then discharged with a constant current of 0.33 C to 2.0 V. The discharge capacity A0 was recorded in Ah at this point, then it was charged with a constant current of 0.33 C to 0.5 A0Ah and set to 50% state of charge (SOC).

[0507] The battery cell was placed at -20 °C for 2 hours and then discharged with a constant current of 4 C for 10 seconds, where ΔU Entladung and ΔI Entladung The DCR data for the discharge of the lithium-ion battery were recorded. The DCR data were calculated using the following formula: R Entladung = ΔU Entladung / ΔI Entladung ,

[0508] where ΔU Entladungrepresents the voltage change within 10 seconds after the start of the discharge and Δl Entladung represents the current value within 10 seconds after the start of the discharge. 2. Cycle performance of the battery cell

[0509] At 30 °C, the battery cell was charged from 20% SOC to 80% SOC using the charging process described above, then charged at 0.33 C to 3.65 V, and after a 30-minute rest period, discharged at 1 C to 20% SOC – this constituted one charge-discharge cycle. After 1000 repetitions of these cycles, the cyclic capacity retention rate of the battery cell was calculated. The higher the cyclic capacity retention rate, the better the cycle performance of the battery cell.

[0510] The battery charging process from a state of charge (SOC) of 20% to 80% proceeded as follows:

[0511] With a constant current of 5.0 C, charging from 20% SOC to 25% SOC is achieved; With a constant current of 5.0 C, charging from 25% SOC to 30% SOC is achieved; With a constant current of 5.0 C, charging from 30% SOC to 35% SOC is achieved; With a constant current of 5.0 C, charging from 35% SOC to 40% SOC is achieved; With a constant current of 4.6 C, it charges from 40% SOC to 45% SOC; With a constant current of 4.3 C, it charges from 45% SOC to 50% SOC; Charging with a constant current of 4.0 C from 50% SOC to 55% SOC; With a constant current of 3.7 C, it charges from 55% SOC to 60% SOC; With a constant current of 3.4 C, it charges from 60% SOC to 65% SOC; With a constant current of 3.1 C, it charges from 65% SOC to 70% SOC; With a constant current of 2.9 C, it charges from 70% SOC to 75% SOC; With a constant current of 2.7 C, the battery is charged from 75% SOC to 80% SOC.

[0512] The test results are shown in Table 1. Table 1 Positive electrode film layer Battery power Length (in mm) Width (in mm) Length / Width DCR 10 seconds at -20 °C (in mΩ) Capacity retention rate after 1000 cycles at 30 °C Energy density (in Wh / L) Comparative example 1 950 40 23,8 4,41 92,8 % 395 Comparative example 2 600 200 3,0 5,32 90,2 % 447 Example 1 950 90 10,6 4,68 92,8 % 430 Example 2-1 950 150 6,3 4,89 92,2 % 439 Example 2-2 950 60 15,8 4,46 93,1 % 410

[0513] In Table 1, in each embodiment and in comparative example 1, The positive electrode tabs are arranged on both sides of the positive electrode current collection section along the longitudinal direction, and the negative electrode tabs are arranged on both sides of the negative electrode current collection section along the longitudinal direction.

[0514] The ratio of the width of the first end face of the positive electrode tab to the width of the positive electrode current collection section is 2 / 3, and the current passage area of ​​the positive electrode terminals on the same side is 314 mm². 2 The ratio of the width of the second end face of the negative electrode tab to the width of the negative electrode current collection section was 2 / 3.

[0515] The positive electrode film layers are arranged on both sides of the positive electrode current collection section along the thickness direction, and the negative electrode film layers are arranged on both sides of the negative electrode current collection section along the thickness direction.

[0516] Table 1 shows that In comparative example 1, the length-to-width ratio of the positive electrode film layer is less than 4, while in comparative example 2, the length-to-width ratio of the positive electrode film layer is greater than 20, and the internal resistance of the battery cell is relatively high; making it impossible to achieve both excellent cycle performance and excellent energy density. In the embodiments of the present application, the length-to-width ratio of the positive electrode film layer is between 4 and 20, which reduces the internal resistance of the battery cell and has a positive effect on improving cycle performance, thus enabling simultaneous improvements in cycle performance and energy density. Comparative example 3 and comparative example 4

[0517] The battery cell was manufactured using a similar process to that described in embodiment 1. The difference compared to embodiment 1 was that the one-sided coating weight of the negative electrode film layer was adjusted. Exemplary embodiment 3-1 and Exemplary embodiment 3-2

[0518] The battery cell was manufactured using a similar process to that described in embodiment 1. The difference compared to embodiment 1 was that the one-sided coating weight of the negative electrode film layer was adjusted.

[0519] The test results are shown in Table 2. Table 2 Coating weight of the positive electrode film layer (in mg / 1540.25 mm²) 2 ) Coating weight of the negative electrode film layer (in mg / 1540.25 mm²) 2 ) Battery power DCR10 seconds at -20 °C (in mΩ) Capacity retention rate after 1000 cycles at 30 °C Energy density (in Wh / L) Comparative example 3 120 55 4,04 93,3 % 400 Comparative example 4 380 175 5,64 89,3 % 445 Example 3-1 160 74 4,28 93,3 % 410 Example 3-2 340 156 5,04 92,2 % 437

[0520] In comparative example 3, the coating weight of the negative electrode film layer is too low to meet the energy density requirements; in comparative example 4, the coating weight of the negative electrode film layer is relatively high, resulting in low impedance of the battery cell and poor cycle life.

[0521] In the embodiments of the present application, the coating weight of the negative electrode film layer is 74 mg / 1540.25 mm². 2 up to 156 mg / 1540.25 mm 2 , which effectively reduces the internal resistance of the battery cell, improves the fast charging performance of the battery cell, thus improving the cycle performance and achieving excellent energy density. Example 4

[0522] The battery cell was manufactured using a similar method to that described in embodiment 1. The difference from embodiment 1 was that in embodiment 1, the ratio of the width of the first end face of the positive electrode tab to the width of the positive electrode current collection section was 2 / 3, and the ratio of the width of the second end face of the negative electrode tab to the width of the negative electrode current collection section was also 2 / 3. In embodiment 4-1, the ratio of the width of the first end face of the positive electrode tab to the width of the positive electrode current collection section was 1 / 3, and the ratio of the width of the second end face of the negative electrode tab to the width of the negative electrode current collection section was 1 / 3. Example 5

[0523] The battery cell was manufactured using a similar process to that described in embodiment 1. The difference compared to embodiment 1 was that in embodiment 1 the current-carrying area of ​​the positive electrode terminal was 31.4 mm². 2 and the current-carrying area of ​​the negative electrode terminal is 314 mm² 2 In embodiment 5, the current-carrying area of ​​the positive electrode terminal was 706 mm². 2 and the current-carrying area of ​​the negative electrode terminal 706 min 2 . Example 6

[0524] The battery cell was manufactured using a similar process to that described in embodiment 1. The difference from embodiment 1 was that the negative electrode sheet was manufactured as follows:

[0525] The negative electrode sheet comprised a negative electrode current collection section, a conductive layer of the negative electrode, and a negative electrode film layer on the negative electrode current collection section, and the negative electrode current collection section was a 5 µm thick copper foil.

[0526] The conductive layer of the negative electrode on the negative electrode current collector section was a 1 µm thick film layer formed by uniformly mixing the conductive agent of the negative electrode made of superconducting carbon, the binder of the negative electrode made of styrene-butadiene rubber (SBR), the thickener made of sodium carboxymethylcellulose (CMC-Na), and the solvent made of water, applying the mixture to the surface of the negative electrode current collector section, and drying, wherein the mass fraction of the conductive agent of the negative electrode in the conductive layer of the negative electrode was 35%, the mass fraction of the binder of the negative electrode in the conductive layer of the negative electrode was 60%, and the mass fraction of the thickener in the conductive layer of the negative electrode was 5%.

[0527] The negative electrode film layer comprised a film layer formed by uniformly applying the negative electrode paste (solvent: deionized water) to the surface of the conductive layer of the negative electrode, followed by drying and cold pressing.

[0528] The negative electrode film layer comprised a first negative electrode film layer, wherein the first negative electrode film layer was located on the surface of the conductive layer of the negative electrode.

[0529] The first negative electrode film layer comprised graphite particles, a conductive agent made of acetylene carbon black, a first lithium-containing binder (a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer was 35%:30%:15%:20%), a negative electrode binder made of styrene-butadiene rubber and a thickening agent made of sodium carboxymethylcellulose with a mass ratio of 96.5:0.5:0.5:1.5:1. The mass fraction of the element lithium in the first lithium-containing binder was 4.8%, the Dv50 value of the graphite particles was 11.3 µm, the graphite particles comprised artificial graphite and a carbon coating layer, the surface of the artificial graphite was coated with the carbon coating layer, and the mass fraction of the carbon coating layer was 3.5%. Comparative example 5

[0530] The battery cell was manufactured using a similar method to that in embodiment 1. The difference from embodiment 1 was that the positive electrode tab was arranged on one side of the positive electrode current collection section and the negative electrode tab was arranged on one side of the negative electrode current collection section.

[0531] The test results are shown in Table 3. Table 3 Battery power DCR 10 seconds at -20 °C (in mΩ) Capacity retention rate after 1000 cycles at 30 °C Energy density (in Wh / L) Example 4 4,83 92,4 % 430 Example 5 4,52 93,0% 430 Example 6 4,71 92,5 % 430 Comparative example 5 4,92 82,7 % 420

[0532] Table 3 shows that In comparative example 5, the current distribution was uneven, the internal resistance of the battery cell was relatively high, and the cycle performance was poor when the positive electrode tab was located on one side of the positive electrode current collection section along the longitudinal direction and the negative electrode tab was located on one side of the negative electrode current collection section along the longitudinal direction. The battery cell has a lower internal resistance as well as excellent cycle performance and energy density if the ratio of the width of the first end face of the positive electrode tab to the width of the positive electrode current collection section is greater than or equal to 1 / 3 and the ratio of the width of the second end face of the negative electrode tab to the width of the negative electrode current collection section is greater than or equal to 1 / 3. The battery cell exhibits low internal resistance as well as excellent cycle performance and energy density when the current-carrying area of ​​the positive electrode terminal is 200 mm². 2 up to 800 mm 2 and the current-carrying area of ​​the negative electrode terminal is 200 mm² 2 up to 800 mm 2 amounts. The battery cell exhibits low internal resistance as well as excellent cycle performance and energy density when the negative electrode film layer is located on at least one side of the negative electrode current collection section.

[0533] Although illustrative embodiments have been demonstrated and described, the person skilled in the art should understand that the above embodiments should not be construed as limitations of the present application and that changes, replacements and modifications to the embodiments may be made without departing from the spirit, principles and scope of the present application. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Test standard GB / T30835-2014

[0200] Test standard GB / T24533-2009

[0203] Test standard JIS / K 0131-1996

[0227] Test standard GB / T 19587-2017

[0233] X-ray diffractometry JIS / K0131-1996

[0305] GB / T5162-2006

[0325] Standard GB / T 36363-2018 “Polyolefin separators for battery cells

[0386] Industry standard HG-T 4067-2015

[0409] GB / T10247-2008

[0412] Reference to GB / T 2013-2010

[0415] Standard JY / T020-1996

[0449] GB / T3 1486-2015 “Electrical performance requirements and test methods for traction batteries for electric vehicles

[0455] GB / T 31467 “Test specification for high-performance lithium-ion traction batteries for HEV

[0505]

Claims

[1] Battery cell comprising an electrode arrangement, wherein the electrode arrangement comprises a positive electrode sheet, a separator and a negative electrode sheet stacked in the thickness direction of the battery cell; where the positive electrode sheet, a positive electrode tab, a positive electrode current collection section and comprising a positive electrode film layer arranged on at least one surface of the positive electrode current collection section along the thickness direction and containing a positive electrode active material, wherein the positive electrode tab is arranged on at least one side of the positive electrode current collection section; the negative electrode sheet, a negative electrode tab, a negative electrode current collection section and comprising a negative electrode film layer arranged on at least one surface of the negative electrode current collection section along the thickness direction and containing a negative electrode active material, wherein the negative electrode tab is arranged on at least one side of the negative electrode current collection section, wherein the ratio of the dimension of the positive electrode film layer along the longitudinal direction of the battery cell to the dimension of the positive electrode film layer along the width direction of the battery cell is 4 to 20, wherein the dimension of the positive electrode film layer along the longitudinal direction is 600 mm to 1200 mm; The one-sided coating weight of the negative electrode film layer is 74 mg / 1540.25 mm². 2 up to 156 mg / 1540.25 mm 2 amounts. [2] Battery cell according to claim 1, wherein the dimension of the positive electrode film layer along the width direction is 60 mm to 150 mm. [3] Battery cell according to claim 1 or 2, wherein the positive electrode tab is arranged on both sides of the positive electrode current collection section along the longitudinal direction. [4] Battery cell according to claim 4, wherein one or more positive electrode tabs are located on the same side of the positive electrode current collection section, wherein the positive electrode tabs each comprise a first end face connected to the positive electrode current collection section, wherein the dimension of the first end face along the width direction is W1, the sum of the dimensions of all first end faces on the same side of the positive electrode current collection section along the width direction is n*W1, and the dimension of the positive electrode current collection section along the width direction is W2, wherein n*W1 / W2 is greater than or equal to 1 / 3, where n represents the number of all positive electrode tabs on the same side of the positive electrode current collection section. [5] Battery cell according to claim 4, wherein n*W1 / W2 is greater than or equal to 2 / 3. [6] Battery cell according to any one of claims 1 to 5, wherein the negative electrode tab is arranged on both sides of the negative electrode current collection section along the longitudinal direction. [7] Battery cell according to claim 6, wherein one or more negative electrode tabs are located on the same side of the negative electrode current collection section, wherein the negative electrode tabs each comprise a second end face connected to the negative electrode current collection section, wherein the dimension of the second end face along the width direction is W3, and the sum of the dimensions of all second end faces on the same side of the negative electrode current collection section along the width direction is m*W3, and the dimension of the negative electrode current collection section along the width direction is W4, wherein m*W3 / W4 is greater than or equal to 1 / 3, where m represents the number of all negative electrode tabs on the same side of the negative electrode current collection section. [8] Battery cell according to claim 7, wherein m*W3 / W4 is greater than or equal to 2 / 3. [9] Battery cell according to any one of claims 1 to 8, wherein the positive electrode tab is arranged on at least one side of the positive electrode current collection section along the width direction. [10] Battery cell according to claim 9, wherein one or more positive electrode tabs are located on the same side of the positive electrode current collection section, wherein the positive electrode tabs each comprise a third end face connected to the positive electrode current collection section, wherein the dimension of the third end face along the longitudinal direction L 10 is the sum of the dimensions of all third end faces on the same side of the positive electrode current collection section along the longitudinal direction s*L 10 is, and the dimension of the positive electrode current collection section along the longitudinal direction L1 is, where s*L 10 / L1 is greater than or equal to 1 / 3, where s represents the number of all positive electrode tabs on the same side of the positive electrode current collector section. [11] Battery cell according to any one of claims 1 to 10, wherein the negative electrode tab is arranged on at least one side of the negative electrode current collection section along the width direction. [12] Battery cell according to claim 11, wherein one or more negative electrode tabs are located on the same side of the negative electrode current collection section, wherein the negative electrode tabs each comprise a fourth end face connected to the negative electrode current collection section, wherein the dimension of the fourth end face along the longitudinal direction L 20 is, and the sum of the dimensions of all fourth end faces on the same side of the negative electrode current collection section along the longitudinal direction p*L 20is, and the dimension of the negative electrode current collection section along the longitudinal direction L2 is, where p*L 20 / L2 is greater than or equal to 1 / 3, where p represents the number of all negative electrode tabs on the same side of the negative electrode current collector section. [13] Battery cell according to any one of claims 1 to 12, wherein along the longitudinal direction the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer, wherein the difference between the dimension of the negative electrode film layer and the dimension of the positive electrode film layer is OH1 and OH1 is 0.5 mm to 3.0 mm; and / or along the width direction the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer, where the difference between the dimension of the negative electrode film layer and the dimension of the positive electrode film layer is OH2 and OH2 is 0.5 mm to 3.0 mm. [14] Battery cell according to any one of claims 1 to 13, wherein the positive electrode tab is arranged on both sides of the positive electrode current collection section along the longitudinal direction, and the negative electrode tab is arranged on both sides of the negative electrode current collection section along the longitudinal direction, along the longitudinal direction the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer, where the difference between the dimension of the negative electrode film layer and the dimension of the positive electrode film layer is OH1; along the width direction the dimension of the negative electrode film layer is larger than the dimension of the positive electrode film layer, where the difference between the dimension of the negative electrode film layer and the dimension of the positive electrode film layer is OH2, where OH1 is larger than OH2. [15] Battery cell according to any one of claims 1 to 14, wherein the battery cell further comprises a positive electrode terminal, wherein the positive electrode terminal is directly welded to the positive electrode tab. [16] Battery cell according to one of claims 1 to 15, wherein the battery cell further comprises a positive electrode terminal, wherein the positive electrode terminal is connected to the positive electrode tab, wherein one or at least two positive electrode terminals are provided. [17] Battery cell according to claim 16, wherein at least two positive electrode terminals are provided. [18] Battery cell according to one of claims 15 to 17, wherein the current-carrying area of ​​a single positive electrode terminal is 200 mm² 2 up to 800 mm 2 amounts. [19] Battery cell according to any one of claims 1 to 18, wherein the battery cell further comprises a negative electrode terminal, wherein the negative electrode terminal is directly welded to the negative electrode tab. [20] Battery cell according to one of claims 1 to 19, wherein the battery cell further comprises a negative electrode terminal, wherein the negative electrode terminal is connected to the negative electrode tab, wherein one or at least two negative electrode terminals are provided. [21] Battery cell according to claim 20, wherein at least two negative electrode terminals are provided. [22] Battery cell according to one of claims 19 to 21, wherein the current-carrying area of ​​a single negative electrode terminal is 200 mm² 2 up to 800 mm 2 amounts. [23] Battery cell according to any one of claims 1 to 22, wherein the battery cell comprises a housing body; wherein the housing body accommodates the electrode arrangement and the thickness of the housing body is 0.1 mm to 0.5 mm. [24] Battery cell according to claim 23, wherein the thickness of the housing body is 0.2 mm to 0.35 mm. [25] Battery cell according to any one of claims 1 to 24, wherein The one-sided coating weight of the positive electrode film layer is 160 mg / 1540.25 mm² 2 up to 340 mg / 1540.25 mm 2 is; and / or The compaction density of the positive electrode film layer is 2.50 g / cm³. 3 up to 2.80 g / cm³ 3 is the value when the battery cell is at 100% charge. [26] Battery cell according to any one of claims 1 to 25, wherein the powder resistance of the positive electrode active material is 1 Ω·cm to 27.5 Ω·cm; and / or The powder compaction density of the positive electrode active material at 30000 N is 2.46 g / cm³. 3 up to 2.8 g / cm³ 3 amounts; and / or The charging capacity per gram of the positive electrode active material at a rate of 0.1 C is 150 mAh / g to 170 mAh / g. [27] Battery cell according to any one of claims 1 to 26, wherein the lithium-containing phosphate with olivine structure comprises: Phosphate particles and a coating layer, wherein the coating layer coats the phosphate particles and the coating layer contains one or more of C, Fe, Ti, Zr, Hf, Ge and Sn. [28] Battery cell according to claim 27, wherein the phosphate particles are a compound with the general formula of Li x1 A y1 Mea M b P 1-c X c Y z includes, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3 and 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5 and 0.9 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5, A includes one or more of Na, K and Mg, Me includes one or more of Mn, Fe, Co and Ni, M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce, X comprises one or more of S, Si, Cl, B, C and N, and Y comprises one or more of O and F. [29] Battery cell according to claim 27 or 28, wherein the coating layer is a fast ion conductor with the general formula of Li 3-d Fe 2-d M2 d (PO x2 ) y2 includes, where M2 includes one or more of Ti, Zr, Hf, Ge and Sn, 0 ≤ d ≤ 1, 0 < x2 < 5, and 0 < y2 < 4. [30] Battery cell according to one of claims 27 to 29, wherein the graphitization degree of the lithium-containing phosphate with olivine structure is 0.15 to 0.

32. [31] Battery cell according to claim 30, wherein the degree of graphitization of the lithium-containing phosphate with olivine structure is 0.19 to 0.

26. [32] Battery cell according to one of claims 27 to 31, wherein the mass fraction of the element carbon in the lithium-containing phosphate with olivine structure is 1% to 2%, and the specific surface area of ​​the lithium-containing phosphate with olivine structure is 5 m² 2 / g up to 18 m 2 / g. [33] Battery cell according to claim 32, wherein the specific surface area of ​​the lithium-containing phosphate with olivine structure is 7.5 m² 2 / g up to 14 m 2 / g. [34] Battery cell according to one of claims 27 to 33, wherein the lithium-containing phosphate with olivine structure is in granular form and the volume distribution particle size of the lithium-containing phosphate with olivine structure meets the following conditions: 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm. [35] Battery cell according to any one of claims 27 to 34, wherein the particle size of the smallest particle in the lithium-containing phosphate with olivine structure is 0.1 µm to 0.4 µm; and / or the particle size of the largest particle in the lithium-containing phosphate with olivine structure is 15 µm to 25 µm. [36] Battery cell according to any one of claims 1 to 35, wherein the ratio of the thickness of the positive electrode current collection section to the thickness of the one-sided positive electrode film layer is 0.05 to 0.

3. [37] Battery cell according to any one of claims 1 to 36, wherein the thickness of the positive electrode current collection section is 10 µm to 15 µm. [38] Battery cell according to one of claims 1 to 37, wherein the positive electrode sheet further comprises a conductive layer of the positive electrode, wherein the conductive layer of the positive electrode is located between the positive electrode film layer and the positive electrode current collection section. [39] Battery cell according to one of claims 1 to 38, wherein the positive electrode film layer further comprises a first material, wherein the first material comprises one or more of ternary material, lithium phosphate, dilithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, trilithium citrate, lithium nickelate and lithium ferrite. [40] Battery cell according to claim 39, wherein the mass fraction of the first material in the positive electrode film layer is 0.5% to 5%. [41] Battery cell according to any one of claims 1 to 40, wherein The compaction density of the negative electrode film layer is 1.15 g / cm³. 3 up to 1.36 g / cm³ 3 is the value when the battery cell is at 100% charge. [42] Battery cell according to any one of claims 1 to 41, wherein the powder resistance of the negative electrode active material is 0.005 Ω·cm to 0.043 Ω·cm; and / or The powder compaction density of the negative electrode active material at 20000 N is 1.5 g / cm³. 3 up to 1.85 g / cm³ 3 amounts; and / or The charging capacity per gram of the negative electrode active material at a rate of 0.1 C is 350 mAh / g to 480 mAh / g. [43] Battery cell according to any one of claims 1 to 42, wherein the negative electrode active material comprises a carbon-based material, wherein the carbon-based material comprises graphite particles, wherein the graphitization degree of the graphite particles is 92.0% to 94.5%. [44] Battery cell according to claim 43, wherein the graphite particles comprise: artificial graphite, which includes secondary particles, and a carbon coating layer with which the surface of the artificial graphite is coated. [45] Battery cell according to claim 44, wherein the mass fraction of amorphous carbon layer, based on the mass of the graphite particles, is 2% to 5%. [46] Battery cell according to any one of claims 1 to 45, wherein the porosity of the negative electrode film layer is 40% to 55%. [47] Battery cell according to any one of claims 1 to 46, wherein the negative electrode film layer is a single-layer film layer, the negative electrode active material is in granular form, and the volume-averaged particle size of the negative electrode active material is 8.2 µm to 13.5 µm. [48] ​​Battery cell according to any one of claims 1 to 46, wherein the negative electrode film layer comprises: a first negative electrode film layer arranged on the surface of the negative electrode current collecting section, wherein the first negative electrode film layer comprises a carbon-based material, and a second negative electrode film layer connected to the side of the first negative electrode film layer facing away from the negative electrode current collection section, wherein the second negative electrode film layer comprises a carbon-based material, wherein the carbon-based material in the first negative electrode film layer and the carbon-based material in the second negative electrode film layer each independently comprise graphite particles, wherein the volume-averaged particle size Dv50 of the graphite particles in the first negative electrode film layer is larger or equal to the volume-averaged particle size Dv50 of the graphite particles in the second negative electrode film layer. [49] Battery cell according to claim 48, wherein the volume-averaged particle size Dv50 of the graphite particles in the first negative electrode film layer is 9.5 µm to 18.5 µm, and / or The volume-averaged particle size Dv50 of the graphite particles in the second negative electrode film layer is 7.8 µm to 14.3 µm. [50] Battery cell according to claim 48 or 49, wherein the bulk density of the carbon-based material in the first negative electrode film layer is less than or equal to the bulk density of the carbon-based material in the second negative electrode film layer. [51] Battery cell according to claim 50, wherein the bulk density of the carbon-based material in the first negative electrode film layer is 0.82 g / cm³ 3 up to 1.21 g / cm³ 3 is, and / or The bulk density of the carbon-based material in the second negative electrode film layer is 0.90 g / cm³. 3 up to 1.25 g / cm³ 3 amounts. [52] Battery cell according to one of claims 48 to 51, wherein the first negative electrode film layer further comprises a first lithium-containing binder and the second negative electrode film layer further comprises a second lithium-containing binder, wherein the mass fraction of the first lithium-containing binder, based on the mass of the first negative electrode film layer, is less than or equal to the mass fraction of the second lithium-containing binder, based on the mass of the second negative electrode film layer. [53] Battery cell according to claim 52, wherein the mass fraction of the first lithium-containing binder, based on the mass of the first negative electrode film layer, is 0.1% to 1%, and / or The mass fraction of the second lithium-containing binder, based on the mass of the second negative electrode film layer, is 0.1% to 1%. [54] Battery cell according to claim 52 or 53, wherein the mass fraction of the element lithium in the first lithium-containing binder is 3% to 10%, and / or the mass fraction of the element lithium in the second lithium-containing binder is 3% to 10%. [55] Battery cell according to any one of claims 52 to 54, wherein The first lithium-containing binder comprises a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the copolymer consists of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and Hydroxyethyl acrylate monomer is derived, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 30% to 50%:15% to 45%:5% to 20%:20% to 35%; and / or the second lithium-containing binder comprises a copolymer of lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate, wherein the copolymer consists of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and Hydroxyethyl acrylate monomer is derived, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 30% to 50%:15% to 45%:5% to 20%:20% to 35%. [56] Battery cell according to any one of claims 1 to 55, wherein the thickness of the negative electrode current collection section is 4 µm to 6 µm. [57] Battery cell according to one of claims 1 to 56, wherein the negative electrode sheet further comprises a conductive layer of the negative electrode, wherein the conductive layer of the negative electrode is located between the negative electrode film layer and the negative electrode current collection section. [58] Battery cell according to any one of claims 1 to 57, wherein the conductivity of the electrolyte solution at room temperature is 13 mS / cm to 20 mS / cm; and / or the viscosity of the electrolyte solution at room temperature is 2.3 mPa·s to 3.5 mPa·s; and / or the density of the electrolyte solution at room temperature is 1.05 g / mL to 1.35 g / mL. [59] Battery cell according to any one of claims 1 to 58, wherein the battery cell comprises an electrolyte solution, wherein the electrolyte solution comprises an organic solvent, wherein the organic solvent comprises a chain-like carboxylic ester solvent, wherein the mass fraction of the chain-like carboxylic ester solvent in the organic solvent is 5% to 75%. [60] Battery cell according to claim 59, wherein the mass fraction of the chain-like carboxylic acid ester solvent in the organic solvent is 30% to 75%. [61] Battery cell according to claim 59 or 60, wherein the chain-like carboxylic acid ester solvent comprises a compound represented by formula I, where in Formula I, R1 comprises a hydrogen atom, a halogen atom, a C1 to C5 alkyl group or a halogenated C1 to C5 alkyl group, R2 comprises a C1 to C5 alkyl group or a halogenated C1 to C5 alkyl group. [62] Battery cell according to claim 61, wherein R1 comprises a hydrogen atom, a halogen atom, a C1 to C3 alkyl group or a halogenated C1 to C3 alkyl group, and / or R2 comprises a C1 to C3 alkyl group or a halogenated C1 to C3 alkyl group. [63] Battery cell according to claim 62, wherein the chain-like carboxylic acid ester solvent comprises one or more of the compounds represented by formula I-1 to formula I-8, [64] Battery cell according to one of claims 59 to 63, wherein the organic solvent further comprises a carbonate solvent, wherein the carbonate solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. [65] Battery cell according to claim 64, wherein the carbonate solvent comprises one or more of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate. [66] Battery cell according to claim 64 or 65, wherein the mass fraction of the carbonate solvent in the organic solvent is 25% to 95%. [67] Battery cell according to one of claims 1 to 66, wherein the electrolyte solution further comprises an additive, the additive comprising one or more of a carbonate additive, a sulfur-containing additive and a lithium salt additive. [68] Battery cell according to claim 67, wherein the carbonate additive comprises one or more of vinylene carbonate and fluoroethylene carbonate, and / or the sulfur-containing additive comprises one or more of ethylene sulfate, bis(ethylene sulfate), butylene sulfite, 1,3-propanesultone, ethylene sulfite and methylenemethanedisulfonate, and / or the lithium salt additive of one or more of lithium difluorophosphate, lithium difluoro(oxalato)borate, Includes lithium tetrafluoroborate and lithium bis(oxalato)borate. [69] Battery cell according to claim 67 or 68, wherein the mass fraction of the additive in the electrolyte solution is 1% to 10%. [70] Battery cell according to claim 69, wherein the mass fraction of the additive in the electrolyte solution is 2% to 8%. [71] Battery cell according to any one of claims 1 to 70, wherein the electrolyte solution further comprises a lithium salt, wherein the lithium salt comprises one or more of a fluorine-containing sulfonylimide salt and lithium hexafluorophosphate. [72] Battery cell according to claim 71, wherein the fluorine-containing sulfonylimide salt comprises one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide. [73] Battery cell according to claim 72, wherein the lithium salt comprises lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, wherein the molar concentration of the lithium bis(fluorosulfonyl)imide is 0.2 mol / L to 0.5 mol / L and the molar concentration of the lithium hexafluorophosphate is 0.5 mol / L to 1.0 mol / L. [74] Battery cell according to claim 73, wherein the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate is 0.2 to 1.

0. [75] Battery cell according to any one of claims 1 to 74, wherein the separator comprises a base film with a porous structure, wherein the thickness of the base film is 6 µm to 12 µm; and / or the porosity of the base film is 35% to 60%. [76] Battery cell according to claim 75, wherein the separator further comprises a functional layer arranged on at least one side of the base film, the functional layer comprising: a first functional layer located on one side of the base film, wherein the first functional layer comprises first inorganic particles, a second functional layer located on the other side of the base film, wherein the second functional layer comprises composite particles, the composite particles comprising second inorganic particles and several non-fluoropolymer particles, wherein the second inorganic particles adhere to the surface of the non-fluoropolymer particles and / or are dispersed inside the non-fluoropolymer particles. [77] Battery cell according to claim 76, wherein the non-fluoropolymer particles comprise an acrylate copolymer. [78] Battery cell according to claim 76 or 77, wherein the first inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide; and / or the second inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide. [79] Battery cell according to one of claims 76 to 78, wherein the average particle size of the second inorganic particles is 5 nm to 100 nm. [80] Battery cell according to any one of claims 1 to 79, wherein the charging time of the charging process of the battery cell from the state of charge of 20% to 80% is 6 minutes to 15 minutes. [81] Battery device comprising a battery cell according to any one of claims 1 to 80. [82] Battery device according to claim 81, wherein the charging time of the charging process of the battery device from the state of charge of 20% to 80% is 6 minutes to 15 minutes. [83] Power-consuming device comprising a battery according to claim 81 or 82.

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