Battery cell, battery device, and electric device

Abstract

The application provides a battery monomer, a battery device and a power utilization device. A positive electrode film layer of the battery monomer comprises a positive electrode active material, the positive electrode active material comprises a lithium-containing transition metal oxide, the lithium-containing transition metal oxide comprises a nickel element, a cobalt element and a manganese element, and the mole percentage of the nickel element is greater than or equal to 0.6 based on the total mole amount of the nickel element, the cobalt element and the manganese element. The battery monomer satisfies that the ratio of the electrolyte mass to the battery monomer capacity is 1.9 g / Ah-2.35 g / Ah, the lithium-containing transition metal oxide comprises single crystal particles, and the number percentage of the single crystal particles is greater than or equal to 90% based on the total number of the lithium-containing transition metal oxide; and the isolation film comprises a base film and inorganic coating layers located on both sides of the base film. The application can reduce the gas production problem of the battery monomer in the charging and discharging process, and can also consider the cycle life and fast discharge performance of the battery monomer.

Description

Cross-reference to related applications

[0001] This application claims priority to PCT application filed on November 21, 2025, with international application number PCT / CN2025 / 136892 entitled "Battery Cell, Battery Device and Electrical Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery device technology, and more specifically, to a battery cell, a battery device, and an electrical device. Background Technology

[0003] Electric vehicles have advantages such as a good driving experience, low cost, and intelligence, and are increasingly recognized by consumers. When electric vehicles are in use, their speed is relatively high, and the battery is in a fast discharge state. The better the fast discharge performance, the better the electric vehicle's range. Therefore, improving the fast discharge performance of the battery is particularly important. Summary of the Invention

[0004] This application was made in view of the above-mentioned issues, and its purpose is to provide a battery cell, a battery device, and an electrical device to improve the fast discharge performance of the battery, reduce the gas production of the battery, and extend its cycle life.

[0005] In a first aspect, this application provides a battery cell, including an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator located between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material, which includes a lithium-containing transition metal oxide. The lithium-containing transition metal oxide includes nickel, cobalt, and manganese, and the molar percentage of nickel is ≥0.6 based on the total molar amount of nickel, cobalt, and manganese. The battery cell satisfies the following: the ratio of electrolyte mass to battery cell capacity is 1.9 g / Ah to 2.35 g / Ah; the lithium-containing transition metal oxide includes single-crystal particles; and the separator includes a base film and inorganic coatings located on both sides of the base film.

[0006] In the above technical solutions, in order to improve the fast-discharge performance of the battery (capacity retention rate under high current conditions), the electrolyte needs to be more fully wetted. Therefore, the ratio of electrolyte mass to battery cell capacity is controlled within the range of 1.9 g / Ah to 2.35 g / Ah. However, the electrolyte content in this range is relatively high, which will cause gas generation problems. Lithium-containing transition metal oxides, including single crystal particles, can reduce side reactions during battery charging and discharging, thereby improving gas generation and extending the cycle life of the battery. At the same time, gas generation will also cause electrolyte wetting problems between the separator and the electrode. In addition, the use of single crystal particles has basically no grain boundaries and pores inside, and the electrode film layer formed is not easily wetted by the electrolyte. This application coats an inorganic coating on both sides of the base film of the separator. The inorganic particles in the inorganic coating can increase the surface roughness of the separator, thereby forming a capillary effect between the separator and the electrode, improving the wetting of the electrode, and thus improving the fast-discharge performance of the battery.

[0007] In some embodiments, the ratio of electrolyte mass to cell capacity is 2.0 g / Ah to 2.3 g / Ah. Within this range, the amount of electrolyte can be more appropriate to ensure proper wetting and improve the battery's fast-discharge performance, while also maintaining the battery's energy density.

[0008] In some embodiments, the proportion of single-crystal particles is ≥95% based on the total number of lithium-containing transition metal oxides. The fact that most of the particles in the lithium-containing transition metal oxides are single-crystal particles can further improve gas generation, extend cycle life, and reduce gas generation, thus having less impact on electrode wetting. Combined with the inorganic coating on the base film surface, this can improve the electrode wetting effect, thereby simultaneously improving the fast-discharge performance of the battery. Optionally, the proportion of single-crystal particles is ≥98% based on the total number of lithium-containing transition metal oxides; further, the proportion of single-crystal particles is 100% based on the total number of lithium-containing transition metal oxides.

[0009] In some embodiments, the thickness of the inorganic coating on one side is 0.5 μm to 2 μm. Within this range, the thickness of the inorganic coating can, on the one hand, increase the roughness of the separator, thereby creating a capillary effect between the separator and the electrode, which is beneficial for electrode wetting and thus improves the fast-discharge performance of the battery; on the other hand, it can also increase the strength of the separator while maintaining the energy density of the battery.

[0010] In some embodiments, the inorganic coating includes inorganic particles, with the inorganic particles accounting for ≥90% of the mass of the inorganic coating. The presence of a higher proportion of inorganic particles in the inorganic coating can further increase the roughness of the separator, thereby improving the wetting effect between the separator and the electrode and enhancing the fast-discharge performance of the battery.

[0011] In some embodiments, the inorganic particles include at least one of boehmite, silica, magnesium hydroxide, alumina, zirconium oxide, magnesium oxide, mullite, or cordierite. These inorganic particles form an inorganic coating, which can increase the surface roughness of the separator to facilitate wetting of the separator and the electrode.

[0012] In some embodiments, the ionic conductivity of the electrolyte is 7.8 mS / cm to 8.5 mS / cm at 25°C. This range of ionic conductivity, when combined with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah), allows for electrolyte wetting while facilitating lithium-ion transport, thereby further improving the battery's fast-discharge performance. Optionally, the ionic conductivity of the electrolyte is 7.8 mS / cm to 8.2 mS / cm at 25°C.

[0013] In some embodiments, the viscosity of the electrolyte at 25°C is 2 mPa·s to 5 mPa·s. This viscosity range, when combined with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah), allows for better wetting of the electrolyte, thereby improving the battery's fast-discharge performance. Optionally, the viscosity of the electrolyte at 25°C is 2.5 mPa·s to 4 mPa·s.

[0014] In some embodiments, the molar percentage of nickel, based on the total molar amount of nickel, cobalt, and manganese, is 0.6 to 0.95. The lithium-containing transition metal oxide is a medium-nickel or high-nickel material, which has a higher capacity to improve the energy density of the battery. Optionally, the molar percentage of nickel, based on the total molar amount of nickel, cobalt, and manganese, is 0.6 to 0.7.

[0015] In some embodiments, the molar percentage of cobalt, based on the total molar amount of nickel, cobalt, and manganese, is 0.025 to 0.3%. Within this range, the cobalt content can stabilize the structure of lithium-containing transition metal oxides, improve the problem of lithium-nickel mixing, and extend the cycle life of the battery.

[0016] In some embodiments, the molar percentage of manganese, based on the total molar amount of nickel, cobalt, and manganese, is 0.025 to 0.3%. Within this range, the manganese content can improve the structural stability of lithium-containing transition metal oxides, enhance battery safety, and also take into account cost.

[0017] In some embodiments, the lithium-containing transition metal oxide further includes a doping element, which includes at least one selected from aluminum, zirconium, magnesium, titanium, vanadium, and tungsten. Aluminum doping can improve the lithium-nickel mixing problem, facilitate lithium-ion diffusion, and improve the battery's fast-discharge performance; zirconium doping can improve the structural stability of the lithium-containing transition metal oxide, which is beneficial for extending the battery's cycle life; magnesium doping can improve the lithium-nickel mixing problem, stabilize the layered structure, and extend the battery's cycle life; titanium doping can form strong Ti-O bonds to suppress oxygen release, improve battery safety performance, and also suppress phase transitions and microcracks, extending the battery's cycle life; vanadium doping can improve the lithium-nickel mixing problem, stabilize the layered structure, and extend the battery's cycle life. + / V 4+ / V 5+ Redox reactions occur between them, contributing additional electrons and increasing battery capacity. They can also suppress drastic changes in cell parameters during charging and discharging, stabilize the layer structure, and extend cycle life. Doping with tungsten can stabilize the surface structure of the material, suppress phase transitions and oxygen loss, thereby improving the cycle life and thermal safety of the battery.

[0018] In some embodiments, the aluminum content is 1500 ppm to 3500 ppm based on the mass of the lithium-containing transition metal oxide. This aluminum doping level, within this range, can improve the lithium-nickel mixing problem, facilitating lithium-ion diffusion; on the other hand, it can also maintain battery capacity and energy density. Optionally, the aluminum content is 1800 ppm to 2500 ppm based on the mass of the lithium-containing transition metal oxide.

[0019] In some embodiments, the zirconium content is 2000 ppm to 3500 ppm based on the mass of the lithium-containing transition metal oxide. Doping with zirconium within this range can improve material stability and extend battery cycle life; on the other hand, it can also maintain battery capacity and energy density. Optionally, the zirconium content is 2100 ppm to 3000 ppm based on the mass of the lithium-containing transition metal oxide.

[0020] In some embodiments, the magnesium content is 30 ppm to 100 ppm based on the mass of the lithium-containing transition metal oxide. This magnesium doping level, within this range, can improve the lithium-nickel mixing problem, stabilize the layered structure, and extend the battery's cycle life; on the other hand, it can also maintain battery capacity and energy density. Optionally, the magnesium content is 40 ppm to 70 ppm based on the mass of the lithium-containing transition metal oxide.

[0021] In some embodiments, the tungsten content is 1500 ppm to 3000 ppm based on the mass of the lithium-containing transition metal oxide. Tungsten doping within this range can effectively stabilize the material surface structure, suppress phase transitions and oxygen loss, thereby improving the battery's cycle life and thermal safety; on the other hand, it can also maintain battery capacity and energy density. Optionally, the tungsten content is 1800 ppm to 2500 ppm based on the mass of the lithium-containing transition metal oxide.

[0022] In some embodiments, the (Dv90-Dv10) / Dv50 value of the positive electrode active material is 1.0 to 1.4. A particle size distribution within this range can increase the compaction density of the electrode, thereby improving the energy density of the battery; simultaneously, it can also adjust the lithium-ion diffusion path, making it more efficient, thus improving the battery's fast-discharge performance. Optionally, the (Dv90-Dv10) / Dv50 value of the positive electrode active material is 1.1 to 1.4.

[0023] In some embodiments, the powder compaction density of the positive electrode active material at 3T pressure is 3.15 g / cm³ to 3.35 g / cm³. This indicates that it allows for closer contact between particles, reducing contact resistance in electron transport, decreasing the probability of contact between the particle material and the electrolyte, and reducing side reactions; it also results in a higher energy density for the battery. Optionally, the powder compaction density of the positive electrode active material at 3T pressure is 3.2 g / cm³ to 3.3 g / cm³.

[0024] In some embodiments, the positive electrode active material I 003 / I 104 The value is 0.95~1.05. This positive electrode active material has a high capacity, but significant lithium-nickel mixing is observed. However, by combining it with doping elements, the lithium-nickel mixing problem can be effectively improved, while also maintaining the material's capacity. Optionally, the I of the positive electrode active material... 003 / I 104 The value is 0.98~1.03.

[0025] In some embodiments, the specific surface area of ​​the positive electrode active material is 1.0 m² / g to 1.4 m² / g. A smaller specific surface area reduces the contact between the material and the electrolyte, improves gas generation, and enhances cycle performance. Furthermore, improved gas generation allows the electrolyte to more easily wet the electrode components, thus aiding in improving the battery's fast-discharge performance. Optionally, the specific surface area of ​​the positive electrode active material is 1.1 m² / g to 1.3 m² / g.

[0026] In some embodiments, the Dv10 value of the positive electrode active material is 0.8 μm to 2.5 μm. Small particles within this particle size range of the positive electrode active material can shorten the diffusion path of lithium ions in the material, allowing for faster extraction and insertion of lithium ions, thereby improving the fast-discharge performance of the battery. Optionally, the Dv10 value of the positive electrode active material is 1 μm to 1.8 μm.

[0027] In some embodiments, the Dv50 value of the positive electrode active material is 2.5 μm to 4.0 μm. The medium-sized particles in the positive electrode active material, within this range, combined with the aforementioned small particles, can result in a higher compaction density of the electrode, which is beneficial for improving the energy density of the battery. Furthermore, the lithium-ion diffusion path is shorter, which is beneficial for improving the battery's fast-discharge performance. Optionally, the Dv50 value of the positive electrode active material is 2.6 μm to 3.8 μm.

[0028] In some embodiments, the Dv90 value of the positive electrode active material is 4.5 μm to 8.0 μm. Large particles in the positive electrode active material within this range can be blended with the aforementioned medium and small particles, which is beneficial for increasing the compaction density of the electrode. Furthermore, blending with the (Dv90-Dv10) / Dv50 range (1.0 to 1.4) makes the lithium-ion diffusion path more rational, thereby improving the fast-discharge performance of the battery. Optionally, the Dv90 value of the positive electrode active material is 5 μm to 6.5 μm.

[0029] In some embodiments, the Dv99 value of the positive electrode active material is 6.5 μm to 9.0 μm. The maximum particle size in the positive electrode active material is within this range, which improves the uniformity and yield of the electrode, and also allows for more uniform current distribution and improved cycle life. Optionally, the Dv99 value of the positive electrode active material is 7 μm to 8.5 μm.

[0030] In some embodiments, the Dn10 value of the positive electrode active material is 0.2 μm to 0.45 μm. The ultrafine powder of the positive electrode active material within this range, when compounded with a (Dv90-Dv10) / Dv50 ratio (1.0 to 1.4), can improve the compaction density of the electrode and optimize the lithium-ion diffusion path, thereby improving the fast-discharge performance of the battery. Optionally, the Dn10 value of the positive electrode active material is 0.25 μm to 0.43 μm.

[0031] In some embodiments, the areal density of the positive electrode film is 0.220 g / 1540.25 mm. 2 ~0.270 g / 1540.25mm 2Within this range, the areal density of the positive electrode film is beneficial for improving the energy density of the battery. Furthermore, its combination with the particle size distribution of the positive electrode active material can optimize the lithium-ion diffusion path and improve the battery's fast-discharge performance. Optionally, the areal density of the positive electrode film is 0.230 g / 1540.25 mm. 2 ~0.260 g / 1540.25mm 2 .

[0032] In some embodiments, the thickness of the positive electrode current collector is 11 μm to 13 μm. This facilitates electron collection and transport while also balancing electrode strength and battery energy density. Optionally, the thickness of the positive electrode current collector is 11.5 μm to 12.5 μm.

[0033] In some embodiments, the porosity of the positive electrode film is 19% to 25%. A porosity within this range, combined with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah), is beneficial for electrolyte wetting and lithium-ion transport, thereby improving the battery's fast-discharge performance; it also maintains good energy density. Optionally, the porosity of the positive electrode film is 20% to 22%.

[0034] In some embodiments, the positive electrode film layer includes a conductive agent, which includes carbon nanotubes, and the mass percentage of carbon nanotubes in the positive electrode film layer is 0.2% to 0.6%. This facilitates the formation of an excellent conductive network in the positive electrode film layer, which is beneficial for electron transport and thus improves the fast discharge performance of the battery. Optionally, the mass percentage of carbon nanotubes in the positive electrode film layer is 0.3% to 0.5%.

[0035] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, which includes graphite. Graphite has a relatively stable structure, small volume change during lithium insertion / extraction, and good reversibility, which can extend the cycle life of the battery. Furthermore, its low voltage plateau allows for higher battery operating voltage, thereby improving the battery's energy density.

[0036] In some embodiments, the areal density of the negative electrode film is 0.160 g / 1540.25 mm. 2 ~0.175 g / 1540.25mm 2 The areal density of the negative electrode film layer is within this range, and combining it with the areal density of the positive electrode film layer is beneficial to improving the energy density of the battery. Optionally, the areal density of the negative electrode film layer is 0.162 g / 1540.25 mm. 2 ~0.172 g / 1540.25mm 2 .

[0037] In some embodiments, the thickness of the negative electrode current collector is 4.0 μm to 6.0 μm. This facilitates electron collection and transport while also balancing electrode strength and battery energy density. Optionally, the thickness of the negative electrode current collector is 4.4 μm to 5.0 μm.

[0038] In some embodiments, the porosity of the negative electrode film is 25% to 35%. Within this porosity range, a combination with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah) is beneficial for electrolyte wetting and lithium-ion transport, thereby improving the battery's fast-discharge performance; it also maintains good energy density. Optionally, the porosity of the negative electrode film is 28% to 31%.

[0039] In some embodiments, the (Dv90-Dv10) / Dv50 ratio of the negative electrode active material is 1.2 to 1.8. A particle size distribution within this range, with a relatively large value, allows for multi-gradation of graphite, increasing the compaction density of the electrode and thus improving the battery's energy density. Simultaneously, the combination of large and small particles forms a mechanically interlocked stable network, reducing the probability of electrode rebound and resulting in good ionic and electronic conductivity, thereby improving the battery's fast-charging performance. Optionally, the (Dv90-Dv10) / Dv50 ratio of the negative electrode active material is 1.3 to 1.7.

[0040] In some embodiments, the Dv10 value of the negative electrode active material is 4.5 μm to 6.0 μm. The small particles of the negative electrode active material within this particle size range, combined with the (Dv90-Dv10) / Dv50 range (1.2 to 1.8) of the negative electrode active material, make it easier to achieve multi-gradation of the negative electrode active material, thus balancing the battery's energy density and fast-charging performance. Simultaneously, a Dv10 value ≥ 4.5 μm results in a relatively small specific surface area of ​​the graphite particles, which can reduce side reactions to some extent and avoid excessive consumption of lithium ions and electrolyte during the formation of the SEI film during the first charge and discharge, thereby improving the battery's initial efficiency. Optionally, the Dv10 value of the negative electrode active material is 5.0 μm to 5.5 μm.

[0041] In some embodiments, the Dv50 value of the negative electrode active material is 9.0 μm to 13 μm. The medium-sized particles in the negative electrode active material, within this range, combined with the aforementioned small particles, can give the electrode a higher compaction density, which is beneficial for improving the battery's energy density and lithium-ion diffusion, thus improving the battery's fast-charging performance. Optionally, the Dv50 value of the negative electrode active material is 10 μm to 11.5 μm.

[0042] In some embodiments, the Dv90 value of the negative electrode active material is 18 μm to 25 μm. Larger particles in the negative electrode active material within this range can improve the flatness and uniformity of the electrode, thus enabling a more uniform lithium insertion / extraction process in the negative electrode film. Optionally, the Dv90 value of the negative electrode active material is 20 μm to 23 μm.

[0043] In some embodiments, the Dv99 value of the negative electrode active material is 28 μm to 38 μm. The maximum particle size in the negative electrode active material is within this range, which improves the uniformity and yield of the electrode, and also allows for more uniform current distribution and improved cycle life. Optionally, the Dv99 value of the negative electrode active material is 30 μm to 35 μm.

[0044] In some embodiments, the graphitization degree of the negative electrode active material is 91% to 94%. This degree of graphitization reduces crystal defects in graphite, improving its electronic conductivity; it also reduces defect sites in graphite, resulting in less lithium ions and electrolyte consumed in the formation of the SEI film, thereby increasing battery capacity. Optionally, the graphitization degree of the negative electrode active material is 92% to 93%.

[0045] In some embodiments, the specific surface area of ​​the negative electrode active material is 3.0 m² / g to 5.0 m² / g. A larger specific surface area provides more lithium-ion active sites, allowing for more uniform lithium-ion insertion and extraction, thereby improving the battery's fast-charging performance. Optionally, the specific surface area of ​​the negative electrode active material is 3.5 m² / g to 4.5 m² / g.

[0046] In some embodiments, the electrolyte includes ethyl methyl carbonate, with the ethyl methyl carbonate comprising 55% to 65% of the electrolyte by mass. The higher amount of ethyl methyl carbonate in the electrolyte results in lower viscosity, allowing the electrolyte viscosity to be within the range of 2 mPa·s to 5 mPa·s. This, combined with the electrolyte mass-to-cell capacity ratio (1.9 g / Ah to 2.35 g / Ah), facilitates electrolyte wetting and lithium-ion transport, thereby improving the battery's fast-discharge and fast-charge performance.

[0047] In some embodiments, the electrolyte further includes ethylene carbonate, which accounts for 20% to 30% of the electrolyte by mass. Ethyl methyl carbonate accounts for 55% to 65% of the electrolyte by mass. Ethyl methyl carbonate has very low viscosity and high ionic conductivity, significantly improving the fast-discharge performance of the battery; therefore, its mass percentage is ≥55%. However, its thermal stability is slightly poor, so its mass percentage is ≤65%. Additionally, some thermally stable ethylene carbonate is added, which helps promote lithium salt dissociation and further improves ionic conductivity, thereby improving the battery's fast-discharge and fast-charge performance. Optionally, ethylene carbonate accounts for 22% to 28% of the electrolyte by mass.

[0048] In some embodiments, the electrolyte further includes diethyl carbonate, with a mass percentage of ≤10% in the electrolyte. Diethyl carbonate has good thermal stability and a slightly higher viscosity than methyl ethyl carbonate. Therefore, controlling its addition amount to ≤10% can improve the battery's fast discharge and fast charge performance while also mitigating gas generation issues. Optionally, the mass percentage of diethyl carbonate in the electrolyte is ≤5%.

[0049] In some embodiments, the electrolyte further includes additives, including at least one of fluoroethylene carbonate, propylene sulfate, vinylene carbonate, ethylene ethylene carbonate, allyl ethylene carbonate, vinyl sulfate, vinyl disulfate, butene sulfite, 1,3-propanesulfonate lactone, vinyl sulfite, and methyl disulfonate.

[0050] In some embodiments, the additive constitutes 1% to 5% of the electrolyte by mass. The additive in the electrolyte can facilitate the formation of a stable CEI film at the positive electrode and a stable SEI film at the negative electrode, thereby extending the cycle life of the battery. Optionally, the additive constitutes 2% to 4% of the electrolyte by mass.

[0051] In some embodiments, the additive includes at least one of fluoroethylene carbonate and propylene sulfate. The addition of fluoroethylene carbonate can form a stable and flexible SEI film on the negative electrode surface. This SEI film is not easily damaged, reducing irreversible loss of active lithium and extending cycle life. The addition of propylene sulfate can form a dense CEI film on the positive electrode surface, isolating the positive electrode active material from the electrolyte, inhibiting the continuous oxidative decomposition of the electrolyte under high voltage, reducing gas production, and extending the battery's cycle life.

[0052] In some embodiments, the electrolyte further includes an electrolyte lithium salt, which includes lithium hexafluorophosphate. Optionally, the electrolyte lithium salt also includes at least one of lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium difluorophosphate. The addition of lithium bis(fluorosulfonyl)imide is beneficial for improving the ionic conductivity of the electrolyte and providing better high and low temperature stability.

[0053] In some embodiments, a polymeric adhesive layer is further disposed on the side of the inorganic coating facing away from the base film. When the ratio of electrolyte mass to battery cell capacity is in the range of 1.9 g / Ah to 2.35 g / Ah, gas generation may occur. A small amount of gas may enter between the separator and the electrode, affecting electrolyte wetting. The formation of the inorganic coating can improve the wetting problem and, when combined with the polymeric adhesive layer, which contains a large amount of polymeric materials (organic matter), it is electrolyte-friendly and can quickly absorb the electrolyte. Furthermore, the inorganic coating locks in the electrolyte, thereby improving the electrolyte wetting effect and enhancing the battery's fast-discharge performance.

[0054] In some embodiments, the polymeric adhesive layer comprises a polymeric material, and the polymeric material accounts for ≥90% of the mass of the polymeric adhesive layer. The polymeric coating contains a large amount of polymeric material to provide better attraction to the electrolyte, which is beneficial for improving the wetting effect of the electrolyte when combined with the inorganic coating.

[0055] In some embodiments, the polymeric adhesive layer comprises a polymeric material, including at least one selected from nitrile rubber, polyvinyl chloride, polypropylene, polyvinyl alcohol, polyethylene, or polyvinylidene fluoride polymers. These polymeric materials facilitate the attraction of the electrolyte, thereby improving the wetting effect of the electrolyte in conjunction with the inorganic coating.

[0056] In some embodiments, the single-sided weight of the polymer adhesive layer is 0.5 mg / 1540.25 mm. 2 ~1.5mg / 1540.25mm 2 This allows the polymer adhesive layer to be distributed in an island-like pattern on the surface of the inorganic coating, so as to cooperate with the inorganic coating. It can also form a capillary effect between the separator and the electrode, which is beneficial to the wetting of the electrolyte.

[0057] In some embodiments, the thickness of the base film is 5μm to 9μm. This can both isolate the positive and negative electrodes, preventing short circuits, and maintain the energy density of the battery.

[0058] In some embodiments, the porosity of the separator is 25% to 40%. Within this porosity range, rapid and uniform lithium-ion transport can be achieved while simultaneously isolating the positive and negative electrodes, preventing short circuits. Optionally, the porosity of the separator is 28% to 35%.

[0059] Secondly, this application provides a battery device including any of the battery cells in the first aspect.

[0060] Thirdly, this application provides an electrical device, including the battery device of the second aspect. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0062] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0063] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0064] Figure 4 This is a schematic diagram of a battery device according to one embodiment of this application.

[0065] Figure 5 yes Figure 4 An exploded view of a battery device according to an embodiment of this application is shown.

[0066] Figure 6 This is a schematic diagram of a battery device used as a power source according to an embodiment of this application.

[0067] Explanation of reference numerals in the attached figures: 1-Battery unit; 2-Upper housing; 3-Lower housing; 4-Battery module; 5-Battery cell; 51-Housing; 52-Electrode assembly; 53-Cover plate. Detailed Implementation

[0068] Hereinafter, embodiments of the battery cell, battery device, and power-consuming device of this application will be described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0069] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0070] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0071] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0072] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0073] During the use of electric vehicles, the battery is usually in a state of high-current discharge. The higher the capacity retention rate of the battery under high-current discharge, the better the driving range of the electric vehicle. In order to achieve a high capacity retention rate of the battery under high-current discharge, more electrolyte can usually be injected. However, in reality, injecting more electrolyte cannot achieve the above purpose.

[0074] Therefore, this application provides a battery cell including an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator is located between the positive and negative electrode. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material, which includes a lithium-containing transition metal oxide. The lithium-containing transition metal oxide includes nickel, cobalt, and manganese. Based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of nickel is ≥0.6. The battery cell satisfies the following: the ratio of electrolyte mass to battery cell capacity is 1.9 g / Ah to 2.35 g / Ah; the lithium-containing transition metal oxide includes single crystal particles; and the separator includes a base film and inorganic coatings located on both sides of the base film.

[0075] The fully discharged battery cell was disassembled in a dry glove box (discharged to 2.5V at 0.33C current), the positive electrode was removed, and the positive electrode was soaked in DMC solution for 12 hours to wash away excess electrolyte and lithium salt. Then the powder was scraped off and calcined at 400±25℃ in air for 12 hours to obtain the positive electrode active material. According to the EPA 6010D-2018 and JY / T 0567-2020 testing standards, aqua regia was used as the digesting agent, and the positive electrode active material was digested under high temperature and high pressure using microwave digestion. The content of nickel, cobalt, and manganese was tested by inductively coupled plasma-atomized emission spectrometry (ICP-AES). The molar amount was calculated based on the content, and the total molar amount of nickel, cobalt, and manganese was A. The molar amount of nickel was a, and the value of a / A was the molar percentage of nickel. The molar amount of cobalt was b, and the value of b / A was the molar percentage of cobalt. The molar amount of manganese was c, and the value of c / A was the molar percentage of manganese.

[0076] The ratio of electrolyte mass to battery cell capacity reflects the wetting effect of the electrolyte. The higher the value, the more fully the electrolyte wets the electrode assembly. However, if the ratio is too high, it will affect the energy density of the battery cell. Therefore, in this application, the ratio of electrolyte mass to battery cell capacity is 1.9 g / Ah to 2.35 g / Ah, which can ensure sufficient electrolyte to wet the electrode assembly while also maintaining the energy density of the battery cell to a certain extent.

[0077] The test method for the ratio of electrolyte mass to battery cell capacity is as follows: At 25℃, the battery is charged at a constant current rate of 0.33C to the charging cutoff voltage of 4.4V, then charged at a constant voltage until the current drops to 0.05C, left to stand for 5 minutes, and then discharged at a constant current rate of 0.33C to 2.5V, left to stand for 5 minutes. This constitutes one charge-discharge cycle, and the resulting discharge capacity is the battery cell capacity FAh. The battery cell is weighed and recorded as m1g. The battery cell (2.5V) is fully disassembled in a dry glove box, and all disassembled components (except for the electrolyte) are soaked in DMC (dimethyl carbonate) for 16 hours, dried, and then soaked and dried in DMC repeatedly three times. The mass of all disassembled components is then recorded as m2g, and the electrolyte mass is (m1-m2)g. The ratio is (m1-m2)g / FAh.

[0078] "Monocrystalline particles" refer to irregular aggregates of one or several primary particles, with a particle size > 500 nm. "Polycrystalline particles" refer to aggregates of dozens to hundreds of primary particles forming spherical or near-spherical cross-sections, with a particle size of 50 nm to 500 nm. The testing method is as follows: The battery cell is disassembled, the positive electrode is removed and dried, and the positive electrode is subjected to brittle fracture under liquid nitrogen to obtain a cross-section. The cross-section is tested using a scanning electron microscope. The LIBMAS lithium-ion battery material microscopic intelligent analysis system is used to automatically identify the monocrystalline particles and all ternary material particles using AI, determining the number of monocrystalline particles as e and the total number of ternary material particles as E. The value of e / E is the ratio of monocrystalline particles to the total number of ternary material particles.

[0079] In the above technical solutions, to improve the fast-discharge performance of the battery, the electrolyte needs to be more fully wetted. Therefore, the ratio of electrolyte mass to battery cell capacity is controlled within the range of 1.9 g / Ah to 2.35 g / Ah. However, the electrolyte content in this range is relatively high, which may lead to gas generation. Lithium-containing transition metal oxides, including single-crystal particles, can reduce side reactions during the charging and discharging process, thereby improving gas generation and extending the cycle life of the battery. At the same time, gas generation can also cause electrolyte wetting problems between the separator and the electrode. In addition, the use of single-crystal particles results in a smaller specific surface area, making the formed electrode film layer difficult to be wetted by the electrolyte. This application coats both sides of the base film of the separator with an inorganic coating. The inorganic particles in the inorganic coating can increase the surface roughness of the separator, thereby forming a capillary effect between the separator and the electrode, improving the wetting of the electrode, and thus improving the fast-discharge performance of the battery.

[0080] In possible examples of this application, the ratio of electrolyte mass to battery cell capacity is 1.9 g / Ah, 1.95 g / Ah, 2.0 g / Ah, 2.05 g / Ah, 2.1 g / Ah, 2.15 g / Ah, 2.2 g / Ah, 2.25 g / Ah, 2.3 g / Ah, or 2.35 g / Ah, or any value within either of these ranges. Optionally, the ratio of electrolyte mass to battery cell capacity is between 2.0 g / Ah and 2.3 g / Ah. Within this range, the amount of electrolyte can be more reasonable to ensure proper electrolyte wetting, thereby improving the battery's fast-discharge performance while also maintaining the battery's energy density.

[0081] In this application, based on the total number of lithium-containing transition metal oxides, the proportion of single-crystal particles is ≥95%. Most of the particles in the lithium-containing transition metal oxides are single-crystal particles, which can further improve the gas generation problem, extend cycle life, and reduce the amount of gas generation, thus having less impact on the wetting of the electrode. In combination with the inorganic coating on the surface of the base film, the wetting effect of the electrode can be improved, thereby improving the fast discharge performance of the battery.

[0082] As an example, based on the total amount of lithium-containing transition metal oxides, the percentage of single-crystal particles is 95%, 96%, 97%, 98%, 99%, or 100%, or any value within either of these ranges; optionally, based on the total amount of lithium-containing transition metal oxides, the percentage of single-crystal particles is ≥98%; further, based on the total amount of lithium-containing transition metal oxides, the percentage of single-crystal particles is 100%. In other embodiments, based on the total amount of lithium-containing transition metal oxides, the percentage of single-crystal particles can also be 90%~100%, 80%~100%, or 70%~100%, etc.

[0083] In some embodiments of this application, the molar percentage of nickel, based on the total molar amount of nickel, cobalt, and manganese, is 0.6, 0.65, 0.7, 0.75, 0.8, 0.9, 0.95, or 0.98, or any value within either of these ranges; optionally, the molar percentage of nickel, based on the total molar amount of nickel, cobalt, and manganese, is 0.6 to 0.95. This lithium-containing transition metal oxide is a medium-nickel or high-nickel material, which has a higher capacity to improve the energy density of the battery. Further, the molar percentage of nickel, based on the total molar amount of nickel, cobalt, and manganese, is 0.6 to 0.7. Even further, the molar percentage of nickel, based on the total molar amount of nickel, cobalt, and manganese, is 0.63 to 0.7.

[0084] In this application, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of cobalt is 0.025~0.3%. Within this range, the cobalt content can stabilize the structure of lithium-containing transition metal oxides, improve the problem of lithium-nickel mixing, and extend the cycle life of the battery.

[0085] As an example, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of cobalt is 0.025, 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3, or any value within either of these ranges. Optionally, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of cobalt is 0.05 to 0.25. Further, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of cobalt is 0.08 to 0.15.

[0086] In this application, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of manganese is 0.025~0.3%. Within this range, the manganese content can improve the structural stability of lithium-containing transition metal oxides, enhance battery safety, and also take cost into consideration.

[0087] As an example, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of manganese is 0.025, 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3, or any value within either of these ranges. Optionally, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of manganese is 0.05 to 0.28. Further, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of manganese is 0.15 to 0.25.

[0088] In this application, the lithium-containing transition metal oxide further includes doping elements, including at least one selected from aluminum, zirconium, magnesium, titanium, vanadium, and tungsten. Aluminum doping can improve the lithium-nickel mixing problem, facilitate lithium-ion diffusion, and improve the battery's fast-discharge performance; zirconium doping can improve the structural stability of the lithium-containing transition metal oxide, which is beneficial for extending the battery's cycle life; magnesium doping can improve the lithium-nickel mixing problem, stabilize the layered structure, and extend the battery's cycle life; titanium doping can form strong Ti-O bonds to suppress oxygen release, improve battery safety performance, and also suppress phase transitions and microcracks, extending the battery's cycle life; vanadium doping can improve the lithium-nickel mixing structure, stabilize the layered structure, and extend the battery's cycle life. + / V 4+ / V 5+Redox reactions occur between them, contributing additional electrons and increasing battery capacity. They can also suppress drastic changes in cell parameters during charging and discharging, stabilize the layer structure, and extend cycle life. Doping with tungsten can stabilize the surface structure of the material, suppress phase transitions and oxygen loss, thereby improving the cycle life and thermal safety of the battery.

[0089] The method for testing the amount of doping elements was as follows: The fully discharged battery was disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The positive electrode was removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt. The powder was then scraped off and calcined at 400±25℃ in air for 12 hours to obtain the positive electrode active material. According to EPA 6010D-2018 and JY / T 0567-2020 testing standards, aqua regia was used as the digesting agent. The positive electrode active material was digested under high temperature and pressure using microwave digestion. The content of each doping element was tested using inductively coupled plasma-atomic emission spectrometry (ICP-AES).

[0090] In some embodiments, the aluminum content is 1500 ppm to 3500 ppm, based on the mass of the lithium-containing transition metal oxide. This aluminum doping level, within this range, can improve the lithium-nickel mixing problem and facilitate lithium-ion diffusion; on the other hand, it can also maintain battery capacity and energy density.

[0091] As an example, the aluminum content is 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, or 3500 ppm, or any value within either of these ranges, based on the mass of the lithium-containing transition metal oxide. Alternatively, the aluminum content is between 1800 ppm and 2500 ppm, based on the mass of the lithium-containing transition metal oxide.

[0092] In some embodiments, the zirconium content is 2000 ppm to 3500 ppm based on the mass of the lithium-containing transition metal oxide. This zirconium doping level, within this range, can improve material stability and extend battery cycle life; on the other hand, it can also maintain battery capacity and energy density.

[0093] As an example, based on the mass of the lithium-containing transition metal oxide, the zirconium content is 2000 ppm, 2200 ppm, 2400 ppm, 2600 ppm, 2800 ppm, 3000 ppm, 3200 ppm, or 3500 ppm, or any value within either of these ranges. Optionally, based on the mass of the lithium-containing transition metal oxide, the zirconium content is between 2100 ppm and 3000 ppm.

[0094] In some embodiments, the magnesium content is 30 ppm to 100 ppm based on the mass of the lithium transition metal oxide. This magnesium doping level, within this range, can improve the lithium-nickel mixing problem, stabilize the layered structure, and extend the battery's cycle life; on the other hand, it can also maintain battery capacity and energy density.

[0095] As an example, the magnesium content is 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, or 100 ppm, or any value within either of these ranges, based on the mass of the lithium-containing transition metal oxide. Optionally, the magnesium content is between 40 ppm and 70 ppm, based on the mass of the lithium-containing transition metal oxide.

[0096] In some embodiments, the tungsten content is 1500 ppm to 3000 ppm, based on the mass of the lithium-containing transition metal oxide. Within this range, the tungsten doping level can effectively stabilize the material surface structure, suppress phase transitions and oxygen loss, thereby improving the battery's cycle life and thermal safety; on the other hand, it can also maintain battery capacity and energy density.

[0097] As an example, the tungsten content is 1500 ppm, 1800 ppm, 2000 ppm, 2300 ppm, 2500 ppm, 2800 ppm, or 3000 ppm, or any value within either of these ranges, based on the mass of the lithium-containing transition metal oxide. Optionally, the tungsten content is between 1800 ppm and 2500 ppm, based on the mass of the lithium-containing transition metal oxide.

[0098] In some embodiments, the (Dv90-Dv10) / Dv50 value of the positive electrode active material is 1.0 to 1.4. A particle size distribution within this range can increase the compaction density of the electrode, thereby improving the energy density of the battery; simultaneously, it can also adjust the diffusion path of lithium ions to make it more reasonable, thus improving the battery's fast-discharge performance.

[0099] The test method for the particle size distribution of the positive electrode active material is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The positive electrode sheet is removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt. The powder is then scraped off and calcined at 400±25℃ in air for 12 hours to obtain the positive electrode active material. Following GB / T19077-2016, particle size distribution is measured using a laser diffraction instrument (such as the Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK). The values ​​of Dv10, Dv50, Dv90, Dv99, and Dn10 are obtained, and the value of (Dv90-Dv10) / Dv50 is calculated.

[0100] As an example, the value of (Dv90-Dv10) / Dv50 of the positive electrode active material is 1.0, 1.1, 1.2, 1.3 or 1.4, or any value within either of these two ranges. Optionally, the value of (Dv90-Dv10) / Dv50 of the positive electrode active material is 1.1 to 1.4.

[0101] In some embodiments, the Dv10 value of the positive electrode active material is 0.8 μm to 2.5 μm. Smaller particles within this particle size range allow for shorter diffusion paths of lithium ions within the material, enabling faster extraction and insertion of lithium ions, thereby improving the fast-discharge performance of the battery.

[0102] As an example, the Dv10 value of the positive electrode active material is 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.3 μm, 2.5 μm, or any value within either of these ranges. Optionally, the Dv10 value of the positive electrode active material is 1 μm to 1.8 μm.

[0103] In some embodiments, the Dv50 value of the positive electrode active material is 2.5 μm to 4.0 μm. The medium-sized particles in the positive electrode active material fall within this range. Combined with the aforementioned small particles, this allows the electrode to have a higher compaction density, which is beneficial for improving the battery's energy density. Furthermore, the lithium-ion diffusion path is shorter, which is beneficial for improving the battery's fast-discharge performance.

[0104] As an example, the Dv50 value of the positive electrode active material is 2.5 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, or 4.0 μm, or any value within either of these ranges. Optionally, the Dv50 value of the positive electrode active material is 2.6 μm to 3.8 μm.

[0105] In some embodiments, the Dv90 value of the positive electrode active material is 4.5 μm to 8.0 μm. Large particles in the positive electrode active material fall within this range and can be blended with the aforementioned medium and small particles, which is beneficial for increasing the compaction density of the electrode. Furthermore, blending with the (Dv90-Dv10) / Dv50 range (1.0 to 1.4) makes the lithium-ion diffusion path more rational, thereby improving the fast-discharge performance of the battery.

[0106] As an example, the Dv90 value of the positive electrode active material is 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, or 8.0 μm, or any value within either of these ranges. Optionally, the Dv90 value of the positive electrode active material is 5 μm to 6.5 μm.

[0107] In some embodiments, the Dv99 value of the positive electrode active material is 6.5 μm to 9.0 μm. The maximum particle size in the positive electrode active material falls within this range, improving electrode uniformity and yield, and also enabling more uniform current distribution and improved cycle life.

[0108] As an example, the Dv99 value of the positive electrode active material is 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, or 9.0 μm, or any value within either of these ranges. Optionally, the Dv99 value of the positive electrode active material is 7 μm to 8.5 μm.

[0109] In some embodiments, the Dn10 value of the positive electrode active material is 0.2 μm to 0.45 μm. The ultrafine powder of the positive electrode active material within this range, when compounded with (Dv90-Dv10) / Dv50 in the range of 1.0 to 1.4, can improve the compaction density of the electrode and make the lithium-ion diffusion path more reasonable, thereby improving the fast discharge performance of the battery.

[0110] As an example, the Dn10 value of the positive electrode active material is 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, or 0.45 μm, or any value within either of these ranges. Optionally, the Dn10 value of the positive electrode active material is 0.25 μm to 0.43 μm.

[0111] In some embodiments, the powder compaction density of the positive electrode active material under 3T pressure is 3.15 g / cm³ to 3.35 g / cm³. This indicates that it can achieve a tighter contact between particles, reducing the contact resistance of electron transport, reducing the probability of contact between the particulate material and the electrolyte, reducing side reactions, and also enabling the battery to have a higher energy density.

[0112] The powder compaction density test method is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The positive electrode is removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt. The powder is then scraped off and calcined at 400±25℃ in air for 12 hours to obtain the positive electrode active material. A mass M of the test material is weighed and added to a mold with a bottom area of ​​S1. A pressure of 3T is applied and held for 30 seconds, then the pressure is released and held for 10 seconds. The powder compaction density of the material under 3T pressure is then recorded and calculated.

[0113] As an example, the powder compaction density of the positive electrode active material under 3T pressure is 3.15 g / cm³, 3.20 g / cm³, 3.25 g / cm³, 3.30 g / cm³, or 3.35 g / cm³, or any value within either of these ranges. Optionally, the powder compaction density of the positive electrode active material under 3T pressure is 3.2 g / cm³ to 3.3 g / cm³.

[0114] In some embodiments, the positive electrode active material I 003 / I 104 The value is 0.95~1.05. This positive electrode active material has a high capacity, but the lithium-nickel mixture is quite obvious. However, when combined with doping elements, it can effectively improve the lithium-nickel mixture problem and also take into account the capacity of the material.

[0115] Among them, I 003 / I 104 The test method is as follows: the fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current), the positive electrode is taken out, the positive electrode is soaked in DMC solution for 12h, the excess electrolyte and lithium salt are washed away, and then the powder is scraped off and calcined at 400±25℃ in air atmosphere for 12h to obtain the positive electrode active material. XRD pattern test is performed using an X-ray diffractometer (Brook D8 Advance). First, the powder sample of the positive electrode active material is placed on the sample stage, the powder sample is compacted with a glass slide, and then placed in the sample chamber. X-ray irradiation is used to obtain the XRD pattern, and the diffraction peak intensity of the (003) crystal plane and the diffraction peak intensity of the (104) crystal plane are determined, and I is calculated. 003 / I 104 The value of .

[0116] As an example, the positive electrode active material I 003 / I 104 The values ​​are 0.95, 0.97, 0.99, 1.01, 1.03, or 1.05, and any value within either of these two ranges. Optionally, the I of the positive electrode active material... 003 / I 104 The value is 0.98~1.03.

[0117] In some embodiments, the specific surface area of ​​the positive electrode active material is 1.0 m² / g to 1.4 m² / g. A smaller specific surface area reduces the contact between the material and the electrolyte, improves gas generation, and enhances cycle performance. Furthermore, improved gas generation allows the electrolyte to more easily wet the electrode components, thus further improving the battery's fast-discharge performance.

[0118] The specific surface area was tested as follows: A fully discharged battery was disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The positive electrode was removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt. The powder was then scraped off and calcined at 400±25℃ in air for 12 hours to obtain the positive electrode active material. The specific surface area of ​​the positive electrode active material was then tested using nitrogen adsorption. Specifically, the positive electrode active material was heated in a vacuum at a certain temperature for a sufficient time to completely remove adsorbed moisture, gases, and other contaminants from its surface. The treated positive electrode active material was then placed in liquid nitrogen for adsorption experiments. The instrument software automatically used the BET equation for fitting and calculation, directly providing the results.

[0119] As an example, the specific surface area of ​​the positive electrode active material is 1.0 m² / g, 1.1 m² / g, 1.2 m² / g, 1.3 m² / g, or 1.4 m² / g, or any value within either of these ranges. Optionally, the specific surface area of ​​the positive electrode active material is between 1.1 m² / g and 1.3 m² / g.

[0120] In this application, the positive electrode active material is the aforementioned ternary material. In other embodiments, in addition to the aforementioned ternary material, a small amount (e.g., 0wt% to 10wt% of the mass of the positive electrode active material) of other positive electrode active materials may be added. Optionally, the mass percentage of other positive electrode active materials is ≤5%; further, the mass percentage of other positive electrode active materials is ≤1%.

[0121] Other positive electrode active materials can be: other lithium transition metal oxides, such as: lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, and lithium nickel manganese oxide, at least one of these. Other positive electrode active materials can also be: other lithium phosphates, such as: lithium iron phosphate (e.g., LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites, at least one of these.

[0122] Optionally, the chemical formula of lithium manganese iron phosphate is Li m1 Fe x1 Mn y1 M1 b1 P z1 Q1 c1 O n1 N1 d1 Wherein, 0.8≤m1≤1.2, 0<x1<1, 0<y1<1, 0.9≤x1+y1≤1, 0.95≤z1≤1, 3.5≤n1≤4, 0≤b1≤0.1, 0≤c1≤0.1, 0≤d1≤0.1; wherein, M1 includes one or more of Cu, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb, V, and Ti, Q1 includes one or more of B, S, Si, and N, and N1 includes one or more of S, F, Cl, and Br.

[0123] Alternatively, other positive electrode active materials may also be: polyanionic compounds may be Li 1+x Mn 1-y A y P 1- z R z O4; where x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, A includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and R includes one or more elements selected from B, S, Si and N; As an optional technical approach in this application, the polyanionic compound can be Li a A e Mn 1-f B f P 1-g C g O 4-n D n Wherein, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements selected from B, S, Si, and N; D includes one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1, e is selected from the range of 0.001 to 0.1, f is selected from the range of 0.001 to 0.5, g is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1, and the second positive electrode active material is electrically neutral.

[0124] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of cathode materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. When the cathode material is applied to the battery system, the molar Li content changes after charge-discharge cycles.

[0125] In the examples of cathode materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0126] In some embodiments, the positive electrode film layer includes a conductive agent, which includes carbon nanotubes, and the mass percentage of carbon nanotubes in the positive electrode film layer is 0.2% to 0.6%. This facilitates the formation of an excellent conductive network in the positive electrode film layer, which is beneficial for electron transport and can improve the fast discharge performance of the battery.

[0127] As an example, the mass percentage of conductive carbon nanotubes in the positive electrode film is 0.2%, 0.3%, 0.4%, 0.5%, or 0.6%, or any value within either of these ranges. Optionally, the mass percentage of carbon nanotubes in the positive electrode film is 0.3% to 0.5%.

[0128] In some embodiments, the conductive agent in the positive electrode film may further include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, and the mass percentage of the conductive agent in the positive electrode film is 0.5% to 3%.

[0129] In some embodiments, the positive electrode film layer may further include a binder, wherein the mass ratio of the positive electrode active material, binder, and conductive agent in the positive electrode film layer is (92~99):(0.5~3):(0.5~3). The positive electrode active material here includes ternary materials and optionally other positive electrode active materials mentioned above, wherein the mass percentage of other positive electrode active materials in the positive electrode active material is ≤10%.

[0130] Optionally, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin. In other embodiments, the positive electrode film layer may also contain other substances, such as dispersants, etc., which are not limited in this application.

[0131] In some embodiments, the areal density of the positive electrode film is 0.220 g / 1540.25 mm. 2~0.270 g / 1540.25 mm². The areal density of the positive electrode film within this range is beneficial for improving the energy density of the battery. Furthermore, its combination with the particle size distribution of the positive electrode active material can optimize the diffusion path of lithium ions and improve the fast discharge performance of the battery.

[0132] The test method for single-sided areal density is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The positive electrode sheet containing the positive electrode film layer on both sides is removed. The positive electrode sheet is immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt, and then dried. Twenty sheets with an area of ​​S2 (e.g., S2 is 1540.25 mm²) are punched out using a punching machine. 2 Take the average mass of the disc as m3, scrape off the positive electrode film, wipe the positive electrode current collector clean and dry it, and take the average mass of the positive electrode current collector as m4. (m3-m4) / (2 S2), which gives the value of the surface density on one side. If it is a positive electrode sheet with a positive electrode film layer on one side, the value of the surface density on one side is (m3-m4) / S2.

[0133] As an example, the areal density of the positive electrode film is 0.220 g / 1540.25 mm. 2 0.230 g / 1540.25mm 2 0.240 g / 1540.25mm 2 0.250 g / 1540.25mm 2 0.260 g / 1540.25mm 2 Or 0.270 g / 1540.25mm 2 , and any value within its two numerical ranges. Optionally, the areal density of the positive electrode film is 0.230 g / 1540.25 mm. 2 ~0.260 g / 1540.25mm 2 .

[0134] In some embodiments, the porosity of the positive electrode film is 19% to 25%. A porosity within this range, combined with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah), is beneficial for electrolyte wetting and lithium-ion transport, thereby improving the battery's fast-discharge performance; it also takes into account the battery's energy density.

[0135] The method for testing the porosity of the positive electrode film is as follows: The fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The positive electrode sheet is removed and soaked in DMC solution for 12 hours to remove excess electrolyte and lithium salt, then dried. Twenty circular wafers with an area of ​​S3 are punched out using a punching machine (the thickness of each small wafer is measured, and the sum of the volumes of the 20 small wafers is calculated as V0). The 20 small wafers are placed in a sample cup, which is then placed in a true density analyzer. The test system is sealed, and helium gas is introduced according to the procedure. The pressure of the gas in the sample chamber and expansion chamber is detected, and the true volume V1 is calculated according to Bohr's law (PV=nRT). The porosity P=(V0-V1) / V0. 100%.

[0136] As an example, the porosity of the positive electrode film is 19%, 20%, 21%, 22%, 23%, 24%, or 25%, or any value within either of these ranges. Optionally, the porosity of the positive electrode film is 20% to 22%.

[0137] In some embodiments, the thickness of the positive electrode current collector is 11 μm to 13 μm. This facilitates electron collection and transport while also balancing electrode strength and battery energy density. As an example, the thickness of the positive electrode current collector is 11 μm, 11.5 μm, 12 μm, 12.5 μm, or 13 μm, or any value within either of these ranges. Optionally, the thickness of the positive electrode current collector is 11.5 μm to 12.5 μm.

[0138] In this application, the positive current collector in the positive electrode sheet can be a metal foil or a composite current collector. For example, aluminum foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0139] After introducing the positive electrode sheet, the preparation method of the positive electrode sheet is explained. For example, the components used to prepare the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0140] In this application, the negative electrode of the electrode assembly includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, which includes graphite (the graphite is artificial graphite and / or natural graphite). Graphite has a relatively stable structure, small volume change during lithium insertion / extraction, and good reversibility, which can extend the cycle life of the battery. Furthermore, its low voltage plateau allows for higher battery operating voltage, thereby increasing the battery's energy density.

[0141] In some embodiments, the (Dv90-Dv10) / Dv50 ratio of the negative electrode active material is 1.2 to 1.8. A particle size distribution within this range, with a relatively large value, allows for multi-gradation of graphite, increasing the compaction density of the electrode and thus improving the battery's energy density. Simultaneously, the combination of large and small particles forms a mechanically interlocked stable network, reducing the probability of electrode rebound and resulting in good ionic and electronic conductivity, thereby improving the battery's fast-charging performance.

[0142] The test method for the particle size distribution of the negative electrode active material is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The negative electrode sheet is removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt. The powder is then scraped off and calcined at 400±25℃ in air for 12 hours to obtain the negative electrode active material. Following GB / T19077-2016, particle size distribution is measured using a laser diffraction instrument (such as the Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK). The values ​​of Dv10, Dv50, Dv90, and Dv99 are obtained, and the value of (Dv90-Dv10) / Dv50 is calculated.

[0143] As an example, the (Dv90-Dv10) / Dv50 value of the negative electrode active material is 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8, or any value within either of these two ranges. Optionally, the (Dv90-Dv10) / Dv50 value of the negative electrode active material is 1.3 to 1.7.

[0144] In some embodiments, the Dv10 value of the negative electrode active material is 4.5 μm to 6.0 μm. The small particles of the negative electrode active material within this particle size range, combined with the (Dv90-Dv10) / Dv50 range (1.2 to 1.8) of the negative electrode active material, make it easier to achieve multi-gradation of the negative electrode active material, thus balancing the battery's energy density and fast-charging performance. Simultaneously, a Dv10 value ≥ 4.5 μm results in a relatively small specific surface area of ​​the small graphite particles, which can reduce side reactions to some extent and avoid excessive consumption of lithium ions and electrolyte during the formation of the SEI film during the first charge and discharge, thereby improving the battery's initial efficiency.

[0145] As an example, the Dv10 value of the negative electrode active material is 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.4 μm, 5.6 μm, 5.8 μm, or 6.0 μm, or any value within either of these ranges. Optionally, the Dv10 value of the negative electrode active material is 5.0 μm to 5.5 μm.

[0146] In some embodiments, the Dv50 value of the negative electrode active material is 9.0 μm to 13 μm. The medium-sized particles in the negative electrode active material, within this range, combined with the aforementioned small particles, can give the electrode a higher compaction density, which is beneficial for improving the battery's energy density and lithium-ion diffusion, thus enhancing the battery's fast-charging performance.

[0147] As an example, the Dv50 value of the negative electrode active material is 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11 μm, 11.5 μm, 12.0 μm, 12.5 μm, or 13 μm, or any value within either of these ranges. Optionally, the Dv50 value of the negative electrode active material is 10 μm to 11.5 μm.

[0148] In some embodiments, the Dv90 value of the negative electrode active material is 18 μm to 25 μm. Larger particles in the negative electrode active material within this range can improve the flatness and uniformity of the electrode, thus enabling a more uniform lithium insertion / extraction / deintercalation formation in the negative electrode film.

[0149] As an example, the Dv90 value of the negative electrode active material is 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, or 25 μm, or any value within either of these ranges. Optionally, the Dv90 value of the negative electrode active material is 20 μm to 23 μm.

[0150] In some embodiments, the Dv99 value of the negative electrode active material is 28 μm to 38 μm. The maximum particle size in the negative electrode active material is within this range, which improves the consistency and yield of the electrode, and also allows for more uniform current distribution and improved cycle life.

[0151] As an example, the Dv99 value of the negative electrode active material is 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, or 38 μm, or any value within either of these ranges. Optionally, the Dv99 value of the negative electrode active material is 30 μm to 35 μm.

[0152] In some embodiments, the graphitization degree of the negative electrode active material is 91% to 94%. This degree of graphitization can reduce the number of crystal defects in graphite, thereby improving the electronic conductivity of graphite; it can also reduce the number of defect sites in graphite, resulting in less lithium ions and electrolyte consumed in the formation of the SEI film, which can improve the battery capacity.

[0153] The method for testing the graphitization degree of the negative electrode active material includes: disassembling a fully discharged battery (discharging to 2.5V at 0.33C current) in a dry glove box, removing the negative electrode sheet, immersing the negative electrode sheet in DMC solution for 12 hours to wash away excess electrolyte and lithium salt, then scraping off the powder, and calcining it at 400±25℃ in air for 12 hours to obtain the negative electrode active material. The interplanar spacing (d002) of the 002 facet of the negative electrode active material is measured using an X-ray diffractometer (Cu Kα target), and the degree of graphitization is calculated using the following formula: Degree of graphitization = (0.3440–d002) / (0.3440–0.3354) × 100%.

[0154] As an example, the graphitization degree of the negative electrode active material is 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, or 94%, or any value within either of these ranges. Optionally, the graphitization degree of the negative electrode active material is 92% to 93%.

[0155] In some embodiments, the specific surface area of ​​the negative electrode active material is 3.0 m² / g to 5.0 m² / g. A larger specific surface area provides more lithium-ion active sites, allowing for more uniform insertion and extraction of lithium ions, thereby improving the battery's fast-charging performance.

[0156] The specific surface area was tested as follows: A fully discharged battery was disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The negative electrode was removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt. The powder was then scraped off and calcined at 400±25℃ in air for 12 hours to obtain the negative electrode active material. The specific surface area of ​​the negative electrode active material was then tested using nitrogen adsorption. Specifically, the negative electrode active material was heated in a vacuum at a certain temperature for a sufficient time to completely remove adsorbed moisture, gases, and other contaminants from its surface. The treated negative electrode active material was then placed in liquid nitrogen for adsorption experiments. The instrument software automatically used the BET equation for fitting and calculation, directly providing the results.

[0157] As an example, the specific surface area of ​​the negative electrode active material is 3.0 m² / g, 3.5 m² / g, 4 m² / g, 4.5 m² / g, or 5 m² / g, or any value within either of these ranges. Optionally, the specific surface area of ​​the negative electrode active material is between 3.5 m² / g and 4.5 m² / g.

[0158] In this application, the negative electrode active material is graphite. In other embodiments, the negative electrode active material also includes a small amount of other negative electrode active materials (e.g., 0wt%~10wt% of the negative electrode active material by mass), such as soft carbon, hard carbon, silicon-based materials, and tin-based materials. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more. Optionally, the mass percentage of other negative electrode active materials is ≤5%; further, the mass percentage of other negative electrode active materials is ≤1%.

[0159] In some embodiments, the negative electrode film layer may optionally include an adhesive. The adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0160] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0161] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0162] In this application, the mass ratio of negative electrode active material, binder, and conductive agent in the negative electrode film layer is (92~99):(0.5~3):(0.5~3). When the mass ratio of these three components in the negative electrode sheet is within the above range, the battery can achieve high energy density, the electrode sheet can achieve high stability, and it also possesses an excellent conductive network. The negative electrode active material here includes graphite and optionally other negative electrode active materials mentioned above, with the other negative electrode active materials accounting for ≤10% of the total mass of the negative electrode active material.

[0163] In some embodiments, the areal density of the negative electrode film is 0.160 g / 1540.25 mm. 2~0.175 g / 1540.25mm 2 Within this range, the areal density of the negative electrode film layer, when combined with the areal density of the positive electrode film layer, is beneficial for improving the energy density of the battery.

[0164] The test method for single-sided areal density is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The negative electrode sheet containing the negative electrode film on both sides is removed. The negative electrode sheet is immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt, and then dried. Twenty sheets with an area of ​​S4 (e.g., S4 is 1540.25 mm²) are punched out using a punching machine. 2 Take the disc, weigh its average mass as m7, then scrape off the negative electrode film, wipe the negative electrode current collector clean and dry it, weigh the average mass of the negative electrode current collector as m8, (m7-m8) / (2 S4), which gives the value of the single-sided areal density. If it is a negative electrode sheet with a negative electrode film layer on one side, the value of the single-sided areal density is (m7-m8) / S4.

[0165] As an example, the areal density of the negative electrode film is 0.160 g / 1540.25 mm. 2 0.162 g / 1540.25mm 2 0.164 g / 1540.25 mm 2 0.166 g / 1540.25 mm 2 0.168 g / 1540.25mm 2 0.170 g / 1540.25mm 2 0.172 g / 1540.25mm 2 Or 0.175 g / 1540.25mm 2 , and any value within its two numerical ranges. Optionally, the areal density of the negative electrode film is 0.162 g / 1540.25 mm. 2 ~0.172 g / 1540.25mm 2 .

[0166] In some embodiments, the porosity of the negative electrode film is 25% to 35%. A porosity within this range, combined with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah), is beneficial for electrolyte wetting and lithium-ion transport, thereby improving the battery's fast-charging performance; it also takes into account the battery's energy density.

[0167] The test method for the porosity of the negative electrode film is as follows: The fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The negative electrode sheet is removed and soaked in DMC solution for 12 hours to remove excess electrolyte and lithium salt, then dried. Twenty circular wafers with an area of ​​S5 are punched out using a punching machine. The thickness of each small wafer is measured, and the sum of the volumes of the 20 wafers is calculated as V0. The 20 wafers are placed in a sample cup, which is then placed in a true density analyzer. The test system is sealed, and helium gas is introduced according to the procedure. By detecting the gas pressure in the sample chamber and expansion chamber, the true volume V1 is calculated according to Bohr's Law (PV=nRT). The porosity P=(V0-V1) / V0. 100%.

[0168] As an example, the porosity of the negative electrode film is 25%, 27%, 29%, 31%, 33%, or 35%, or any value within either of these ranges. Alternatively, the porosity of the negative electrode film is 28% to 31%.

[0169] In some embodiments, the thickness of the negative electrode current collector is 4.0 μm to 6.0 μm. This facilitates electron collection and transport while also balancing electrode strength and battery energy density. As an example, the thickness of the negative electrode current collector is 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, or 6.0 μm, or any value within either of these ranges. Optionally, the thickness of the negative electrode current collector is 4.5 μm to 5.0 μm.

[0170] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0171] In other embodiments, the negative current collector of the negative electrode sheet may typically include a current collector body and a base coating. The base coating may be disposed on at least one side of the current collector body. The base coating basically does not contain negative electrode active material, but may include a small amount of carbon material. However, the carbon material forms a thin coating and cannot play the role of negative electrode active material.

[0172] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry. The negative electrode slurry is then coated onto a negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode sheet is obtained.

[0173] In this application, the separator includes a base membrane and inorganic coatings located on both sides of the base membrane. The base membrane can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0174] In some embodiments, the inorganic coating includes inorganic particles, with the inorganic particles accounting for ≥90% of the mass of the inorganic coating. The presence of a higher proportion of inorganic particles in the inorganic coating can further increase the roughness of the separator, thereby improving the wetting effect between the separator and the electrodes (including between the separator and the positive electrode, and between the separator and the negative electrode), thus enhancing the battery's fast discharge and fast charge performance.

[0175] Optionally, the inorganic coating comprises inorganic particles and a binder, which are mixed (optionally with the addition of a solvent) and then applied to the surface of a base film, and dried to form the inorganic coating. Optionally, the binder in the inorganic coating includes at least one of nitrile rubber, polyvinyl chloride, polypropylene, polyvinyl alcohol, polyethylene, or polyvinylidene fluoride polymers. The mass percentage of inorganic particles in the inorganic coating is 90%, 92%, 94%, 96%, or 98%, or any value within either of these ranges.

[0176] The test method for the mass ratio of inorganic particles in the inorganic coating is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The separator is removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt, then dried. A portion of the inorganic coating powder is scraped off, dried, and weighed as m5g. This powder is then calcined at 400±25℃ in air for 12 hours, and the mass of the inorganic particles is weighed as m6g. The ratio of m6 / m5 is calculated. 100% represents the mass percentage of inorganic particles in the inorganic coating.

[0177] Optionally, the inorganic particles include at least one of boehmite, silica, magnesium hydroxide, alumina, zirconium oxide, magnesium oxide, mullite, or cordierite. These inorganic particles form an inorganic coating, which can increase the surface roughness of the separator to facilitate wetting of the separator and the electrode.

[0178] In some embodiments, the thickness of the inorganic coating on one side is 0.5 μm to 2 μm. Within this range, the thickness of the inorganic coating can, on the one hand, increase the roughness of the separator, thereby creating a capillary effect between the separator and the electrode, which is beneficial for electrode wetting and thus improves the battery's fast discharge and fast charge performance; on the other hand, it can also improve the strength of the separator while maintaining the battery's energy density.

[0179] The method for testing the single-sided thickness of the inorganic coating is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The separator is removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt, followed by drying. The separator is then cut using laser cutting, and the cross-section is photographed using a scanning electron microscope. Five arbitrary points are selected along the length of the cross-section to determine the thickness of the single-sided inorganic coating. The average value is then calculated to obtain the single-sided thickness.

[0180] As an example, the thickness of the inorganic coating on one side is 0.5 μm, 1 μm, 1.5 μm or 2 μm, or any value within either of these ranges.

[0181] In this embodiment, a polymeric adhesive layer is further provided on the side of the inorganic coating facing away from the base film. When the ratio of electrolyte mass to battery cell capacity is in the range of 1.9 g / Ah to 2.35 g / Ah, gas generation may occur. A small amount of gas can enter between the separator and the electrode, affecting electrolyte wetting. The formation of the inorganic coating can improve the wetting problem and, when combined with the polymeric adhesive layer, which contains a large amount of polymeric materials (organic matter), it is electrolyte-friendly and can quickly absorb the electrolyte. Furthermore, the inorganic coating locks in the electrolyte, thereby improving the electrolyte wetting effect and enhancing the battery's fast discharge and fast charge performance.

[0182] In some embodiments, the polymeric adhesive layer comprises a polymeric material, and the polymeric material accounts for ≥90% of the mass of the polymeric adhesive layer. The polymeric coating contains a large amount of polymeric material to provide better attraction to the electrolyte, which is beneficial for improving the wetting effect of the electrolyte when combined with the inorganic coating.

[0183] Optionally, the polymeric adhesive layer includes a polymeric material. The polymeric material is mixed with a solvent and then coated onto the surface of a base film, and after drying, a polymeric adhesive coating is formed. Optionally, the polymeric material includes at least one of nitrile rubber, polyvinyl chloride, polypropylene, polyvinyl alcohol, polyethylene, or polyvinylidene fluoride polymers. The polymeric adhesive layer may consist entirely of polymeric materials, and a small amount of inorganic particles may also be added. The mass percentage of the polymeric material in the polymeric adhesive layer is 90%, 92%, 94%, 96%, 98%, or 100%, or any value within either of these ranges.

[0184] In some embodiments, the single-sided weight of the polymer adhesive layer is 0.5 mg / 1540.25 mm. 2 ~1.5mg / 1540.25mm 2 This allows the polymer adhesive layer to be distributed in an island-like pattern on the surface of the inorganic coating, so as to cooperate with the inorganic coating. It can also form a capillary effect between the separator and the electrode, which is beneficial to the wetting of the electrolyte.

[0185] The test method for the single-sided weight of the polymer adhesive layer is as follows: Disassemble the fully discharged battery (discharge to 2.5V at 0.33C current) in a dry glove box, remove the separator membrane coated with polymer adhesive layers on both sides, soak the separator membrane in DMC solution for 12 hours to remove excess electrolyte and lithium salt, and then dry it. Cut a separator membrane with an area of ​​S6, weigh it as M0, soak the separator membrane in NMP for 12 hours, remove the polymer adhesive layer, dry it, and weigh it as M1. The single-sided weight of the polymer adhesive layer is (M0-M1) / (2 S6). If it is a release liner coated with a polymer adhesive layer on one side, the weight of the polymer adhesive layer on one side is (M0-M1) / S6.

[0186] As an example, the single-sided weight of the polymer adhesive layer is 0.5 mg / 1540.25 mm. 2 0.7 mg / 1540.25 mm 2 0.9 mg / 1540.25 mm 2 1.1 mg / 1540.25 mm 2 1.3 mg / 1540.25 mm 2 Or 1.5 mg / 1540.25 mm 2 , and any value within its two numerical ranges.

[0187] In some embodiments, the thickness of the base film is 5μm to 9μm. This can both isolate the positive and negative electrodes, preventing short circuits, and maintain the energy density of the battery.

[0188] The method for testing the thickness of the base film is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The separator is removed and immersed in DMC solution for 12 hours to remove excess electrolyte and lithium salt, then dried. The separator is cut using laser cutting, and the cross-section is photographed using a scanning electron microscope. Five arbitrary points are selected along the length of the cross-section to determine the thickness of the base film at each point. The average value is then calculated to obtain the thickness of the base film.

[0189] As an example, the thickness of the base film is 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm or 9 μm, and any value within either of these ranges.

[0190] In some embodiments, the porosity of the separator is 25% to 40%. Within this porosity range, rapid and uniform lithium-ion transport can be achieved while isolating the positive and negative electrodes and preventing short circuits.

[0191] The porosity test method for the separator membrane is as follows: A fully discharged battery is disassembled in a dry glove box (discharged to 2.5V at 0.33C current). The separator membrane is removed and soaked in DMC solution for 12 hours to remove excess electrolyte and lithium salt, then dried. Twenty circular wafers with an area of ​​S7 are punched out using a punching machine. The thickness of the separator membrane is measured, and the average value is taken at 20 locations. The volume of the separator membrane is calculated as V0. The separator membrane is placed in a sample cup, and the sample cup containing the sample is placed in a true density analyzer. The test system is sealed, and helium gas is introduced according to the procedure. By detecting the gas pressure in the sample chamber and expansion chamber, the true volume V1 is calculated according to Bohr's Law (PV=nRT). The porosity P=(V0-V1) / V0 100%.

[0192] As an example, the porosity of the separator is 25%, 28%, 30%, 32%, 35%, 38%, or 40%, or any value within either of these ranges. Optionally, the porosity of the separator is 28% to 35%. In some embodiments, at 25°C, the ionic conductivity of the electrolyte is 7.8 mS / cm to 8.5 mS / cm. This ionic conductivity, within this range, combined with the electrolyte mass to cell capacity ratio (1.9 g / Ah to 2.35 g / Ah), allows for electrolyte wetting while facilitating lithium-ion transport, thereby further improving the battery's fast-discharge performance.

[0193] The test method for the ionic conductivity of the electrolyte at 25℃ is as follows: refer to the density meter method on page 5 of the industry standard HG / T4067-2015 "Lithium Hexafluorophosphate Electrolyte". Specific test steps: Disassemble the fully discharged battery (discharge to 2.5V at 0.33C current) in a dry glove box. Take approximately 100mL of the fully discharged electrolyte sample in a dry, clean, corrosion-resistant sample bottle, seal it, and place it in a constant temperature water bath at 25℃±0.5℃. Shake it occasionally. When the sample temperature is constant, replace the bottle cap with a rubber stopper containing electrodes. When the temperature is within the range of 25℃±0.5℃, read the data in the conductivity meter; this is the ionic conductivity of the tested sample.

[0194] As an example, at 25°C, the ionic conductivity of the electrolyte is 7.8 mS / cm, 7.9 mS / cm, 8.0 mS / cm, 8.1 mS / cm, 8.2 mS / cm, 8.3 mS / cm, 8.4 mS / cm, or 8.5 mS / cm, or any value within either of these ranges. Optionally, at 25°C, the ionic conductivity of the electrolyte is 8.0 mS / cm to 8.2 mS / cm.

[0195] In some embodiments, the viscosity of the electrolyte at 25°C is 2 mPa·s to 5 mPa·s. When the electrolyte viscosity is within this range, and combined with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah), the wetting effect of the electrolyte can be improved, thereby enhancing the battery's fast-discharge performance.

[0196] The method for testing the viscosity of the electrolyte at 25℃ is as follows: Based on Appendix D of the national standard GB / T10247-2008, a rotational viscometer is used for testing. The specific test steps are as follows: Disassemble the fully discharged battery (discharge to 2.5V at 0.33C current) in a dry glove box. Take a certain mass of electrolyte sample and place it in a sample container. Use a Brookfield DV2TLV rotational viscometer for testing. At a certain temperature, the shear force experienced by the rotor rotating continuously at a constant speed in the sample causes the spring to generate torque. The torque is proportional to the viscosity, thus yielding the viscosity value.

[0197] The testing equipment meets the following testing environment conditions: 1. External environment of the equipment: temperature: 25℃, humidity: RH<80%; 2. Internal environment of the equipment: 2 / 3 of the sample container is immersed in the water bath, the medium is water, and water is used to keep the sample at a constant temperature.

[0198] As an example, at 25°C, the viscosity of the electrolyte is 2 mPa·s, 2.5 mPa·s, 3 mPa·s, 3.5 mPa·s, 4 mPa·s, 4.5 mPa·s, or 5 mPa·s, or any value within either of these ranges. Optionally, at 25°C, the viscosity of the electrolyte is between 2.5 mPa·s and 4 mPa·s.

[0199] In some embodiments, the electrolyte includes ethyl methyl carbonate, and the mass percentage of ethyl methyl carbonate in the electrolyte is 55% to 65% based on the total mass of the electrolyte. The higher amount of ethyl methyl carbonate in the electrolyte results in lower viscosity, allowing the electrolyte viscosity to be within the range of 2 mPa·s to 5 mPa·s. This, combined with the ratio of electrolyte mass to battery cell capacity (1.9 g / Ah to 2.35 g / Ah), facilitates electrolyte wetting and lithium-ion transport, thereby improving the battery's fast-discharge and fast-charge performance.

[0200] As an example, the mass percentage of methyl ethyl carbonate in the electrolyte is 55%, 57%, 59%, 61%, 63%, or 65%, or any value within either of these ranges.

[0201] In some embodiments, the electrolyte further includes ethylene carbonate, which accounts for 20% to 30% of the total mass of the electrolyte. Ethyl methyl carbonate accounts for 55% to 65% of the mass. Ethyl methyl carbonate has very low viscosity and high ionic conductivity, significantly improving the fast-discharge performance of the battery; therefore, its mass percentage is ≥55%. However, its thermal stability is slightly poor, so its mass percentage is ≤65%. Additionally, some thermally stable ethylene carbonate (20% to 30%) is added, which helps promote lithium salt dissociation and further improves ionic conductivity, thereby enhancing the battery's fast-discharge and fast-charge performance.

[0202] As an example, the mass percentage of ethylene carbonate in the electrolyte is 20%, 22%, 24%, 26%, 28%, or 30%, or any value within either of these ranges. Optionally, the mass percentage of ethylene carbonate in the electrolyte is 22% to 28%.

[0203] In some embodiments, the electrolyte also includes diethyl carbonate. Based on the total mass of the electrolyte, the mass percentage of diethyl carbonate in the electrolyte is ≤10%. Diethyl carbonate has good thermal stability and its viscosity is slightly higher than that of methyl ethyl carbonate. Therefore, its addition amount is controlled to ≤10% in order to improve the fast discharge and fast charging performance of the battery, while also improving the gas generation problem of the battery.

[0204] As an example, the mass percentage of diethyl carbonate in the electrolyte is 0%, 2%, 4%, 6%, 8%, or 10%, or any value within either of these ranges. Optionally, the mass percentage of diethyl carbonate in the electrolyte is ≤8% based on the total mass of the electrolyte. Further, the mass percentage of diethyl carbonate in the electrolyte is ≤5% based on the total mass of the electrolyte. Still further, the mass percentage of diethyl carbonate in the electrolyte is ≤1% based on the total mass of the electrolyte.

[0205] In some embodiments, the electrolyte further includes additives, wherein the additives constitute 1% to 5% of the electrolyte by mass, based on the total mass of the electrolyte. The additives in the electrolyte can facilitate the formation of a stable CEI film at the positive electrode and a stable SEI film at the negative electrode, thereby extending the cycle life of the battery. As an example, the additives constitute 1%, 2%, 3%, 4%, or 5% of the electrolyte by mass, or any value within either of these ranges.

[0206] In some embodiments, the additive includes at least one selected from fluoroethylene carbonate, propylene sulfate, vinylene carbonate, ethylene ethylene carbonate, allyl ethylene carbonate, vinyl sulfate, vinyl disulfate, butenyl sulfite, 1,3-propanesulfonate lactone, vinyl sulfite, and methyl methylene disulfonate. Optionally, the additive includes at least one selected from fluoroethylene carbonate and propylene sulfate. The addition of fluoroethylene carbonate can form a stable and flexible SEI film on the negative electrode surface. The SEI film is not easily damaged, which can reduce the irreversible loss of active lithium and extend the cycle life. The addition of propylene sulfate can form a dense CEI film on the positive electrode surface, which can isolate the positive electrode active material from the electrolyte, inhibit the continuous oxidative decomposition of the electrolyte under high voltage, reduce gas production, and extend the cycle life of the battery. When multiple additives are included, the mass percentage of the additive in the electrolyte refers to the sum of the mass percentages of the various additives.

[0207] In some embodiments, the electrolyte further includes an electrolyte lithium salt, which includes lithium hexafluorophosphate. In this application, based on the total mass of the electrolyte, the electrolyte lithium salt accounts for 10% to 17% of the electrolyte by mass; exemplarily, the electrolyte lithium salt accounts for 10%, 11%, 12%, 13%, 14%, 15%, 16%, or 17% of the electrolyte by mass, or any value within either of these ranges. Optionally, based on the total mass of the electrolyte, the electrolyte lithium salt accounts for 12% to 15% of the electrolyte by mass.

[0208] In other embodiments, the electrolyte salt in the electrolyte may further include a small amount of other electrolyte salts (the concentration of other electrolyte salts in the electrolyte ≤ 1%), including at least one of lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate. Optionally, the electrolyte lithium salt may further include at least one of lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium difluorophosphate. The addition of lithium bis(fluorosulfonyl)imide is beneficial for improving the ionic conductivity of the electrolyte and provides better high and low temperature stability.

[0209] In this application, the testing methods for each component in the electrolyte include: testing based on the national standard GB / T 6041-2020. Specific testing steps are as follows: disassemble the fully discharged battery in a dry glove box (discharge to 2.5V at 0.33C current), take approximately 100mL of the fully discharged electrolyte sample in a dry, clean, corrosion-resistant sample bottle, and use mass spectrometry to test the content of each component in the electrolyte, calculating the mass percentage of each component in the electrolyte.

[0210] In this application, positive and negative electrode sheets are stacked sequentially, and a separator is placed between the positive and negative electrode sheets to provide isolation, resulting in a bare cell. Alternatively, the bare cell can be obtained after stacking or winding. The bare cell is placed in an outer package, electrolyte is injected, and then it is sealed to obtain a battery cell.

[0211] In some embodiments, the battery cell also includes an outer packaging that can be used to encapsulate electrode assemblies.

[0212] In some embodiments, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0213] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is a schematic diagram of a battery cell 5 according to one embodiment of this application.

[0214] In some embodiments, Figure 2 yes Figure 1 The exploded view of the battery cell 5 according to one embodiment of this application is shown below. Figure 2 The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0215] In some embodiments, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0216] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0217] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0218] In some embodiments, the battery modules described above can also be assembled into a battery device. The number of battery modules contained in the battery device can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery device.

[0219] Figure 4 This is a schematic diagram of a battery device according to one embodiment of this application. Figure 5 yes Figure 4 An exploded view of a battery device according to an embodiment of this application is shown. (Refer to...) Figure 4 and Figure 5 The battery device 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0220] In addition, this application also provides an electrical device, which includes at least one of the battery device, battery module, or battery device provided in this application. The battery device, battery module, or battery device can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0221] As an electrical device, a battery device, battery module, or battery cell can be selected according to its usage requirements.

[0222] Figure 6 This is a schematic diagram of a battery device according to an embodiment of this application, used as a power source for an electrical device. Please refer to [link / reference]. Figure 6 The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the device's requirements for long-cycle and high-energy-density battery devices, battery devices or battery modules can be used.

[0223] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a battery as their power source.

[0224] Example The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0225] Example 1 This embodiment provides a lithium-ion battery cell, and the preparation method is as follows: (1) Preparation of positive electrode sheet A positive electrode slurry with a solid content of 65% was prepared by mixing lithium-containing transition metal oxide, carbon nanotubes, conductive carbon black, and polyvinylidene fluoride (PVDF) in a mass ratio of 97:0.5:1.0:1.5, adding N-methylpyrrolidone as a solvent, and stirring thoroughly to obtain a homogeneous mixture. This slurry was then coated onto both sides of a 12 μm thick aluminum foil used as a positive electrode current collector. After drying, cold pressing, and slitting, a positive electrode film was formed, yielding the positive electrode sheet. The areal density of the positive electrode film on one side was 0.250 g / 1540.25 mm. 2 The porosity is 22%; all lithium-containing transition metal oxides are single-crystal particles, and the molar ratio of Ni, Co, and Mn in the lithium-containing transition metal oxides is 0.68:0.1:0.22. Among them, the doping amount of Al is 2000ppm and the doping amount of Zr is 2000ppm; the value of (Dv90-Dv10) / Dv50 is 1.32, Dv10 is 1.5μm, Dv50 is 3.4μm, Dv90 is 6.0μm, Dv99 is 8.0μm, and Dn10 is 0.35μm. The powder compaction density of the lithium-containing transition metal oxides under 3T pressure is 3.25 g / cm³, the I003 / I104 value is 1.01, and the specific surface area is 1.25 m² / g. (2) Preparation of negative electrode sheet Artificial graphite, conductive carbon black, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 97:0.5:1.5:1, and then deionized water was added. After thorough mixing, a negative electrode slurry with a solid content of 50% was prepared. The negative electrode slurry was coated on both sides of a 5μm thick copper foil current collector. After drying, cold pressing, and slitting, a negative electrode film was formed, resulting in the negative electrode sheet. The areal density of the negative electrode film on one side was 0.167 g / 1540.25 mm. 2 The porosity is 29.5%; the (Dv90-Dv10) / Dv50 ratio of the artificial graphite is 1.50, Dv10 is 5.2μm, Dv50 is 10.5μm, Dv90 is 21μm, Dv99 is 32μm, the degree of graphitization is 92.5%, and the specific surface area is 4.05 m² / g.

[0226] (3) Preparation of the separating membrane Using a 7 μm thick polyethylene film as the base film, boehmite and nitrile rubber were mixed at a mass ratio of 95:5, and N-methylpyrrolidone (NMP) was added and thoroughly stirred to prepare an inorganic slurry with a solid content of 80%. This inorganic slurry was coated onto both surfaces of the base film, and after drying, formed an inorganic coating with a thickness of 0.75 μm. Then, a layer of nitrile rubber was coated onto each of the two inorganic coating surfaces, forming a single-sided weight of 1 mg / 1540.25 mm. 2 The polymer adhesive layer has a porosity of 31%.

[0227] (4) Electrolyte Ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate were mixed, and lithium hexafluorophosphate was dissolved in the solution to obtain an electrolyte. In this electrolyte, ethyl methyl carbonate accounted for 56% by mass, diethyl carbonate for 4% by mass, ethylene carbonate for 25% by mass, lithium hexafluorophosphate for 14% by mass, fluoroethylene carbonate for 0.5% by mass, and propylene sulfate for 0.5% by mass. The electrolyte had a viscosity of 2.5 mPa·s and an ionic conductivity of 8.1 mS / cm.

[0228] (5) Battery assembly The above-mentioned positive electrode, separator, negative electrode, and separator are stacked in sequence to form a stacked battery cell; the battery cell is placed in an outer packaging to obtain a soft-pack battery cell, and the electrolyte prepared above is injected. After processes such as encapsulation, standing, formation, and aging, the lithium-ion battery cell of Example 1 is obtained, wherein the electrolyte injection coefficient of the battery is 2.25 g / Ah (wherein, the electrolyte injection coefficient refers to the ratio of the mass of injected electrolyte to the theoretical capacity of the battery).

[0229] Example 2 Example 2 provides a lithium-ion battery cell, which differs from Example 1 in that: In step (5), the injection coefficient is 2.35 g / Ah. Example 3 Example 3 provides a lithium-ion battery cell, which differs from Example 1 in that: In step (5), the injection coefficient is 2.45 g / Ah.

[0230] Example 4 Example 4 provides a lithium-ion battery cell, which differs from Example 1 in that: In step (5), the injection coefficient is 2.55 g / Ah.

[0231] Example 5 Example 5 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (5), the injection coefficient is 2.65 g / Ah.

[0232] Example 6 Example 6 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (4), methyl ethyl carbonate, diethyl carbonate, and ethylene carbonate are mixed, and lithium hexafluorophosphate is dissolved in the above solution to obtain an electrolyte. In this electrolyte, the mass percentage of methyl ethyl carbonate is 57%, the mass percentage of diethyl carbonate is 5%, the mass percentage of ethylene carbonate is 23%, the mass percentage of lithium hexafluorophosphate is 14%, the mass percentage of fluoroethylene carbonate is 0.5%, and the mass percentage of propylene sulfate is 0.5%. The viscosity of the electrolyte is 2.45 mPa·s, and the ionic conductivity of the electrolyte is 8.15 mS / cm.

[0233] Example 7 Example 7 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (4), methyl ethyl carbonate and ethylene carbonate are mixed, and lithium hexafluorophosphate is dissolved in the above solution to obtain an electrolyte. In this electrolyte, the mass percentage of methyl ethyl carbonate is 60%, the mass percentage of ethylene carbonate is 25%, the mass percentage of lithium hexafluorophosphate is 14%, the mass percentage of fluoroethylene carbonate is 0.5%, the mass percentage of propylene sulfate is 0.5%, the viscosity of the electrolyte is 2.3 mPa·s, and the ionic conductivity of the electrolyte is 8.2 mS / cm.

[0234] Example 8 Example 8 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (1), based on the total number of lithium transition metal oxides, the number of single crystal particles accounts for 90%, and the rest are polycrystalline particles. Example 9 Example 9 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (1), based on the total number of lithium transition metal oxides, the number of single crystal particles accounts for 95%, and the rest are polycrystalline particles. Example 10 Example 10 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (1), based on the total number of lithium transition metal oxides, the number of single crystal particles accounts for 98%, and the rest are polycrystalline particles. Example 11 Example 11 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (3), a 7 μm thick polyethylene film was used as the base film. Silica and nitrile rubber were mixed at a mass ratio of 95:5, and N-methylpyrrolidone (NMP) was added and thoroughly stirred to prepare an inorganic slurry with a solid content of 80%. The inorganic slurry was coated onto both surfaces of the base film, and after drying, an inorganic coating with a thickness of 1 μm was formed. Then, a layer of nitrile rubber was coated onto each of the two inorganic coating surfaces, forming a single-sided weight of 1 mg / 1540.25 mm. 2 The polymer adhesive layer has a porosity of 31.2%.

[0235] Example 12 Example 12 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (3), a polyethylene film with a thickness of 7 μm is used as the base film. Alumina and nitrile rubber are mixed at a mass ratio of 95:5, and N-methylpyrrolidone (NMP) is added and thoroughly stirred to prepare an inorganic slurry with a solid content of 80%. The inorganic slurry is coated on both surfaces of the base film, and after drying, an inorganic coating with a thickness of 1.25 μm is formed. Then, a layer of nitrile rubber is coated on each of the two inorganic coating surfaces to form a single-sided weight of 1 mg / 1540.25 mm. 2 The polymer adhesive layer has a porosity of 31.5%.

[0236] Example 13 Example 13 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (3), a 7 μm thick polyethylene film was used as the base film. Boehmite and nitrile rubber were mixed at a mass ratio of 95:5, and N-methylpyrrolidone (NMP) was added and thoroughly stirred to prepare an inorganic slurry with a solid content of 80%. The inorganic slurry was coated on both surfaces of the base film, and after drying, an inorganic coating with a thickness of 1.5 μm was formed. Then, a layer of nitrile rubber was coated on each of the two inorganic coating surfaces to form a single-sided weight of 1 mg / 1540.25 mm. 2 The polymer adhesive layer has a porosity of 31.8%.

[0237] Example 14 Example 14 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (1), the molar ratio of Ni, Co and Mn in lithium transition metal oxide is 0.7:0.1:0.2, wherein the doping amount of Al is 2000ppm and the doping amount of Zr is 2000ppm. Example 15 Example 15 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (1), the molar ratio of Ni, Co and Mn in lithium transition metal oxide is 0.68:0.1:0.22, and no Al and Zr doping is performed.

[0238] Comparative Example 1 Comparative Example 1 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (5), the injection coefficient is 2.15 g / Ah.

[0239] Comparative Example 2 Comparative Example 2 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (1), the lithium-containing transition metal oxide is a polycrystalline particle.

[0240] Comparative Example 3 Comparative Example 3 provides a lithium-ion battery cell, which differs from Example 3 in that: In step (3), a polyethylene film with a thickness of 7 μm is used as the base film, and a layer of nitrile rubber is coated on each of the two surfaces of the base film to form a single-sided weight of 1 mg / 1540.25 mm. 2 The polymer adhesive layer has a porosity of 30.1%.

[0241] The preparation conditions of some lithium-ion battery cells in Examples 1 to 15 and Comparative Examples 1 to 3 are shown in Table 1.

[0242] Table 1. Some preparation conditions of lithium-ion battery cells

[0243]

[0244]

[0245]

[0246] Test case The lithium-ion battery cells prepared in Examples 1 to 15 and Comparative Examples 1 to 3 were tested, and the test results are shown in Table 2. The specific test methods are as follows: 1. The ratio of electrolyte mass to cell capacity At 25℃, the battery is charged at a constant current rate of 0.33C to the charging cutoff voltage of 4.4V, then charged at a constant voltage until the current drops to 0.05C, left to stand for 5 minutes, and then discharged at a constant current rate of 0.33C to 2.5V, left to stand for 5 minutes. This constitutes one charge-discharge cycle, and the resulting discharge capacity is the capacity of the battery cell, FAh. The battery cell is weighed and recorded as m1g. The battery cells (2.5V) are fully disassembled in a dry glove box, and all disassembled components (except the electrolyte) are soaked in DMC (dimethyl carbonate) for 16 hours, dried, and this process is repeated three times. The mass of all disassembled components is then recorded as m2g, and the electrolyte mass is (m1-m2)g. The ratio of electrolyte mass to battery cell capacity is (m1-m2)g / FAh.

[0247] 2. Performance of lithium-ion battery cells (1) Gas production At 25°C, the battery was charged at a constant current rate of 0.33C to the charging cutoff voltage of 4.4V, then charged at a constant voltage until the current dropped to 0.05C, and then discharged at a constant current rate of 0.33C to 2.5V, obtaining the initial discharge capacity C0. The battery was then charged at a constant current rate of 0.33C to the charging cutoff voltage of 4.4V, and then charged at a constant voltage until the current dropped to 0.05C. C. When the battery outer packaging is a hard shell, a small hole is made at the edge of the hard shell, and the battery is sealed inside the aluminum-plastic film. The volume V0 of the sealed aluminum-plastic film is tested using the water displacement method at 25°C. Then, the entire aluminum-plastic film-sealed cell is placed in a constant temperature chamber at 60°C for 100 days. After cooling for 8 hours, the volume V1 of the sealed aluminum-plastic film is tested at 25°C. The increased volume is the gas production volume. When the battery outer packaging is a soft pack (e.g., aluminum-plastic film), the volume V0 of the sealed aluminum-plastic film is tested using the water displacement method at 25°C. Then, the entire aluminum-plastic film-sealed cell is placed in a constant temperature chamber at 60°C for 100 days. After cooling for 8 hours, the volume V1 of the sealed aluminum-plastic film is tested at 25°C. The increased volume is the gas production volume. Gas production (ml / Ah) = Gas production volume / First discharge capacity = (V1 - V0) / C0.

[0248] (2) Cycle life At 45℃, the battery was charged at a constant current rate of 0.33C to the charging cutoff voltage of 4.4V, then charged at a constant voltage until the current dropped to 0.05C. After resting for 5 minutes, it was discharged at a constant current rate of 0.33C to 2.5V and then rested for 5 minutes. This constitutes one charge-discharge cycle, and the resulting discharge capacity is recorded as the initial discharge capacity C0. Following this method, the battery was subjected to cyclic charge-discharge tests. At the 1000th cycle, the obtained discharge capacity was C1. The capacity retention rate (1000 cycles) = C1 / C0. 100%.

[0249] (3) Fast playback performance At 25°C, the battery was charged at a constant current rate of 0.33C to the charging cutoff voltage of 4.4V, then charged at a constant voltage until the current dropped to 0.05C, and allowed to rest for 5 minutes. It was then discharged at a constant current rate of 0.33C to 2.5V, and allowed to rest for 5 minutes. This constitutes one charge-discharge cycle, and the resulting discharge capacity is recorded as the initial discharge capacity C0. The battery was then charged at a constant current rate of 0.33C to the charging cutoff voltage of 4.4V, then charged at a constant voltage until the current dropped to 0.05C, and allowed to rest for 5 minutes. Finally, the battery was discharged at a constant current rate of 2C to 2.5V, and allowed to rest for 5 minutes. This constitutes one charge-discharge cycle, and the resulting discharge capacity is recorded as the 2C rate discharge capacity C2.

[0250] 2C retention rate = C2 / C0 100%.

[0251] Table 2. Parameters and performance test results of individual battery cells.

[0252]

[0253] As can be seen from Tables 1 and 2, in Comparative Example 1, the electrolyte injection coefficient of the battery cell is relatively low, resulting in a low ratio of electrolyte mass to battery cell capacity, which in turn leads to low capacity retention and fast discharge performance (2C retention). In Comparative Example 2, the lithium-containing transition metal oxide of the positive electrode active material is a polycrystalline particle, resulting in high gas production and low capacity retention. In Comparative Example 3, the separator base film lacks an inorganic coating, leading to low capacity retention and fast discharge performance (2C retention).

[0254] In Examples 1 to 15 of this application, the ratio of electrolyte mass to battery cell capacity is within a suitable range (1.9 g / Ah to 2.35 g / Ah), the lithium-containing transition metal oxide contains single crystal particles, and an inorganic coating is provided on the base film of the separator, which can reduce the gas production of the battery and improve the battery's capacity retention rate and fast discharge performance (2C retention rate).

[0255] A comparison of Examples 1 to 5 shows that different electrolyte injection coefficients result in different ratios of electrolyte mass to cell capacity. When the ratio is between 2 g / Ah and 2.3 g / Ah, the gas production of the battery is relatively low (between 0.5 mL / Ah and 0.6 mL / Ah), while the capacity retention rate and fast discharge performance (2C retention rate) are relatively high (capacity retention rate above 90.2% and 2C retention rate above 97.4%).

[0256] A comparison of Examples 3, 6, and 7 shows that the electrolyte viscosity is between 2 mPa·s and 3 mPa·s, the ratio of electrolyte mass to battery cell capacity is within a suitable range (1.9 g / Ah to 2.35 g / Ah), the lithium-containing transition metal oxide contains single-crystal particles, and the base film of the separator is coated with an inorganic coating, which can result in low gas production (between 0.52 mL / Ah and 0.55 mL / Ah), and high capacity retention and fast discharge performance (2C retention rate) (capacity retention rate between 90.6% and 91%, 2C retention rate above 98%).

[0257] A comparison of Examples 3 and 8-10 shows that a higher content of single crystals significantly improves the gas production of the battery and increases the capacity retention rate. Although the 2C retention rate decreases, the decrease is minimal and has virtually no impact on the battery's 2C retention rate. Therefore, the lithium-containing transition metal oxide in the battery of this application, which includes single crystal particles, and the ratio of electrolyte mass to battery cell capacity within a suitable range (1.9 g / Ah~2.35 g / Ah), along with the inorganic coating on the base film of the separator, can maintain the battery's fast discharge performance (2C retention rate) while reducing the gas production and improving the battery's capacity retention rate.

[0258] A comparison of Examples 3 and 11-13 shows that the selection of boehmite, silicon dioxide, or alumina as inorganic particles significantly improves battery performance. When the thickness of the inorganic coating is between 0.75 μm and 1.5 μm, and when combined with lithium-containing transition metal oxides, including single-crystal particles, and when the ratio of electrolyte mass to battery cell capacity is within a suitable range (1.9 g / Ah to 2.35 g / Ah), the gas production of the battery can be reduced, and the battery capacity retention rate and fast discharge performance (2C retention rate) are both high.

[0259] A comparison of Example 3 and Example 15 shows that doping with Zr and Al in lithium-containing transition metal oxides can reduce the amount of gas produced by the battery and improve the battery's capacity retention and fast discharge performance.

[0260] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, The device includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator is located between the positive electrode and the negative electrode. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material. The positive electrode active material includes a lithium-containing transition metal oxide. The lithium-containing transition metal oxide includes nickel, cobalt, and manganese. Based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of nickel is ≥0.6%. The battery cell satisfies the following conditions: the ratio of electrolyte mass to battery cell capacity is 1.9 g / Ah to 2.35 g / Ah; the lithium-containing transition metal oxide includes single crystal particles, and the number of single crystal particles accounts for ≥90% of the total number of lithium-containing transition metal oxides; the separator includes a base film and inorganic coatings located on both sides of the base film.

2. The battery cell according to claim 1, characterized in that, The ratio of the electrolyte mass to the battery cell capacity is 2.0 g / Ah to 2.3 g / Ah; or / and, based on the total amount of lithium-containing transition metal oxides, the number of single crystal particles accounts for ≥95%; or / and, the single-sided thickness of the inorganic coating is 0.5 μm to 2 μm; or / and, the inorganic coating includes inorganic particles, and the mass percentage of the inorganic particles in the inorganic coating is ≥90%; or / and, at 25°C, the ionic conductivity of the electrolyte is 7.8 mS / cm to 8.5 mS / cm; or / and, at 25°C, the viscosity of the electrolyte is 2 mPa·s to 5 mPa·s.

3. The battery cell according to claim 2, characterized in that, The number of single crystal particles accounts for ≥98% of the total number of lithium-containing transition metal oxides; or / and the inorganic particles include at least one of boehmite, silicon dioxide, magnesium hydroxide, aluminum oxide, zirconium oxide, magnesium oxide, mullite, or cordierite; or / and the ionic conductivity of the electrolyte is 7.8 mS / cm to 8.2 mS / cm at 25°C; or / and the viscosity of the electrolyte is 2.5 mPa·s to 4 mPa·s at 25°C.

4. The battery cell according to any one of claims 1 to 3, characterized in that, Based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of nickel is 0.6 to 0.95; or / and, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of cobalt is 0.025 to 0.3; or / and, based on the total molar amount of nickel, cobalt, and manganese, the molar percentage of manganese is 0.025 to 0.3; or / and, the lithium-containing transition metal oxide further includes a dopant element, which includes at least one of aluminum, zirconium, magnesium, titanium, vanadium, and tungsten.

5. The battery cell according to claim 4, characterized in that, The molar percentage of nickel, cobalt, and manganese is 0.6 to 0.7% based on the total molar amount of nickel, cobalt, and manganese; and / or the content of aluminum is 1500 ppm to 3500 ppm based on the mass of the lithium-containing transition metal oxide; and / or the content of zirconium is 2000 ppm to 3500 ppm based on the mass of the lithium-containing transition metal oxide; and / or the content of magnesium is 30 ppm to 100 ppm based on the mass of the lithium-containing transition metal oxide; and / or the content of tungsten is 1500 ppm to 3000 ppm based on the mass of the lithium-containing transition metal oxide.

6. The battery cell according to claim 5, characterized in that, Based on the mass of the lithium-containing transition metal oxide, the aluminum content is 1800 ppm to 2500 ppm; or / and, based on the mass of the lithium-containing transition metal oxide, the zirconium content is 2100 ppm to 3000 ppm; or / and, based on the mass of the lithium-containing transition metal oxide, the magnesium content is 40 ppm to 70 ppm; or / and, based on the mass of the lithium-containing transition metal oxide, the tungsten content is 1800 ppm to 2500 ppm.

7. The battery cell according to claim 1, characterized in that, The value of (Dv90-Dv10) / Dv50 of the positive electrode active material is 1.0~1.4; or / and, the powder compaction density of the positive electrode active material under 3T pressure is 3.15 g / cm³~3.35 g / cm³; or / and, the I of the positive electrode active material 003 / I 104 The value is 0.95~1.05; or / and, the specific surface area of ​​the positive electrode active material is 1.0 m² / g~1.4 m² / g.

8. The battery cell according to claim 7, characterized in that, The value of (Dv90-Dv10) / Dv50 of the positive electrode active material is 1.1~1.4; or / and, the powder compaction density of the positive electrode active material under 3T pressure is 3.2g / cm³~3.3g / cm³; or / and, the I of the positive electrode active material 003 / I 104 The value is 0.98~1.03; or / and, the specific surface area of ​​the positive electrode active material is 1.1 m² / g~1.3 m² / g.

9. The battery cell according to claim 7 or 8, characterized in that, The Dv10 value of the positive electrode active material is 0.8 μm to 2.5 μm; or / and the Dv50 value of the positive electrode active material is 2.5 μm to 4.0 μm; or / and the Dv90 value of the positive electrode active material is 4.5 μm to 8.0 μm; or / and the Dv99 value of the positive electrode active material is 6.5 μm to 9.0 μm; or / and the Dn10 value of the positive electrode active material is 0.2 μm to 0.45 μm.

10. The battery cell according to claim 9, characterized in that, The Dv10 value of the positive electrode active material is 1 μm to 1.8 μm; or / and the Dv50 value of the positive electrode active material is 2.6 μm to 3.8 μm; or / and the Dv90 value of the positive electrode active material is 5 μm to 6.5 μm; or / and the Dv99 value of the positive electrode active material is 7 μm to 8.5 μm; or / and the Dn10 value of the positive electrode active material is 0.25 μm to 0.43 μm.

11. The battery cell according to claim 1, characterized in that, The areal density of the positive electrode film is 0.220 g / 1540.25 mm. 2 ~0.270 g / 1540.25mm 2 ; or / and, the thickness of the positive electrode current collector is 11μm~13μm; or / and, the porosity of the positive electrode film is 19%~25%; or / and, the positive electrode film includes a conductive agent, the conductive agent includes carbon nanotubes, and the mass percentage of the carbon nanotubes in the positive electrode film is 0.2%~0.6%.

12. The battery cell according to claim 11, characterized in that, The areal density of the positive electrode film is 0.230 g / 1540.25 mm. 2 ~0.260 g / 1540.25mm 2 The thickness of the positive current collector is 11.5 μm to 12.5 μm; the porosity of the positive electrode film is 20% to 22%; and the positive electrode film includes a conductive agent, which includes carbon nanotubes, and the carbon nanotubes account for 0.3% to 0.5% of the mass of the positive electrode film.

13. The battery cell according to claim 1, characterized in that, The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes graphite.

14. The battery cell according to claim 13, characterized in that, The areal density of the negative electrode film is 0.160 g / 1540.25 mm. 2 ~0.175 g / 1540.25mm 2 The thickness of the negative electrode current collector is 4.0 μm to 6.0 μm; and the porosity of the negative electrode film is 25% to 35%.

15. The battery cell according to claim 14, characterized in that, The areal density of the negative electrode film is 0.162 g / 1540.25 mm. 2 ~0.172 g 1540.25mm 2 ; or / and, the thickness of the negative electrode current collector is 4.4 μm to 5.0 μm; or / and, the porosity of the negative electrode film is 28% to 31%.

16. The battery cell according to claim 13, characterized in that, The (Dv90-Dv10) / Dv50 value of the negative electrode active material is 1.2~1.8; or / and, the graphitization degree of the negative electrode active material is 91%~94%; or / and, the specific surface area of ​​the negative electrode active material is 3.0 m² / g~5.0 m² / g.

17. The battery cell according to claim 16, characterized in that, The (Dv90-Dv10) / Dv50 value of the negative electrode active material is 1.3~1.7; or / and, the graphitization degree of the negative electrode active material is 92%~93%; or / and, the specific surface area of ​​the negative electrode active material is 3.5 m² / g~4.5 m² / g.

18. The battery cell according to claim 16, characterized in that, The Dv10 value of the negative electrode active material is 4.5 μm to 6.0 μm; or / and, the Dv50 value of the negative electrode active material is 9.0 μm to 13 μm; or / and, the Dv90 value of the negative electrode active material is 18 μm to 25 μm; or / and, the Dv99 value of the negative electrode active material is 28 μm to 38 μm.

19. The battery cell according to claim 18, characterized in that, The Dv10 value of the negative electrode active material is 5.0 μm to 5.5 μm; or / and the Dv50 value of the negative electrode active material is 10 μm to 11.5 μm; or / and the Dv90 value of the negative electrode active material is 20 μm to 23 μm; or / and the Dv99 value of the negative electrode active material is 30 μm to 35 μm.

20. The battery cell according to claim 1, characterized in that, The electrolyte comprises ethyl methyl carbonate, wherein the mass percentage of ethyl methyl carbonate in the electrolyte is 55% to 65%; and / or the electrolyte further comprises additives, wherein the additives include at least one selected from fluoroethylene carbonate, propylene sulfate, vinylene carbonate, ethylene ethylene carbonate, allyl ethylene carbonate, vinyl sulfate, vinyl disulfate, butenyl sulfite, 1,3-propanesulfonate lactone, vinyl sulfite, and methyl methylene disulfonate.

21. The battery cell according to claim 20, characterized in that, The electrolyte further includes ethylene carbonate, wherein the mass percentage of ethylene carbonate in the electrolyte is 20% to 30%; or / and the electrolyte further includes diethyl carbonate, wherein the mass percentage of diethyl carbonate in the electrolyte is ≤10%; or / and the additive in the electrolyte accounts for 1% to 5% of the mass percentage.

22. The battery cell according to claim 21, characterized in that, The mass percentage of diethyl carbonate in the electrolyte is ≤5%; or / and the mass percentage of ethylene carbonate in the electrolyte is 22%~28%; or / and the additive includes at least one of fluoroethylene carbonate and propylene sulfate; or / and the electrolyte further includes an electrolyte lithium salt, the electrolyte lithium salt including lithium hexafluorophosphate.

23. The battery cell according to claim 22, characterized in that, The electrolyte lithium salt also includes at least one of lithium difluorosulfonylimide, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium difluorophosphate.

24. The battery cell according to claim 1, characterized in that, A polymer adhesive layer is further provided on the side of the inorganic coating opposite to the base film; and / or the thickness of the base film is 5μm~9μm; and / or the porosity of the isolation membrane is 25%~40%.

25. The battery cell according to claim 24, characterized in that, The polymeric adhesive layer comprises a polymeric material, wherein the polymeric material accounts for ≥90% of the mass of the polymeric adhesive layer; and / or, the single-sided weight of the polymeric adhesive layer is 0.5 mg / 1540.25 mm. 2 ~1.5mg / 1540.25mm 2 ; or / and, the polymeric adhesive layer comprises a polymeric material, the polymeric material comprising at least one of nitrile rubber, polyvinyl chloride, polypropylene, polyvinyl alcohol, polyethylene, or polyvinylidene fluoride polymer; or / and, the porosity of the separator is 28% to 35%.

26. A battery device, characterized in that, Includes the battery cell described in any one of claims 1 to 25.

27. An electrical appliance, characterized in that, Includes the battery device as described in claim 26.

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