Battery and electrical apparatus

Abstract

A battery (2) and an electrical apparatus. The battery (2) comprises a plurality of battery cells (10) and a first busbar component (30a). The plurality of battery cells (10) are arranged along the thickness direction of each battery cell (10), and the battery cells (10) each comprise a housing (12) and an electrode assembly (11) accommodated in the housing. The expansion pressure of each battery cell (10) in the thickness direction is 0.5 MPa to 2.4 MPa. The first busbar component (30a) is electrically connected to at least two battery cells (10) arranged in the thickness direction, and the first busbar component (30a) is of a multi-layer structure. The electrode assembly comprises a positive electrode plate (111), a negative electrode plate (112), and a separator (113) located between the positive electrode plate (111) and the negative electrode plate (112). The positive electrode plate (111) comprises a positive electrode current collector (1111) and a positive electrode film layer (1112) provided on at least one side of the positive electrode current collector (1111). The positive electrode film layer (1112) comprises a positive electrode active material. The positive electrode active material comprises a lithium-containing phosphate having an olivine structure. The negative electrode plate (112) comprises a negative electrode current collector (1121) and a negative electrode film layer (1122) provided on at least one side of the negative electrode current collector (1121). The negative electrode film layer (1122) comprises a negative electrode active material. The negative electrode active material comprises a carbon-based material.

Description

Battery and power consuming device TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, and more particularly, to a battery and a power consuming device. BACKGROUND

[0002] Batteries are widely used in electronic devices, such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, electric tools, and the like.

[0003] In the development of battery technology, how to improve the reliability of the battery is a research direction in the battery technology.

[0004] SUMMARY

[0005] The present application provides a battery and a power consuming device, which can improve the reliability of the battery.

[0006] In a first aspect, the embodiments of the present application provide a battery, which includes a plurality of battery monomers and a first current collecting component. The plurality of battery monomers are arranged along the thickness direction of the battery monomers, and the battery monomers include a shell and an electrode assembly contained in the shell. The expansion pressure of the battery monomers in the thickness direction is 0.5-2.4 MPa. The first current collecting component is electrically connected to at least two battery monomers arranged along the thickness direction, and the first current collecting component has a multi-layer structure. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator film between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material. The positive electrode active material includes lithium-containing phosphate with an olivine structure. The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material. The negative electrode active material includes a carbon-based material.

[0007] The expansion pressure of the battery monomers is related to the density of the electrode assembly. The embodiments of the present application can allow the battery monomers to have an expansion pressure greater than or equal to 0.5 MPa in the thickness direction, thereby improving the density of the electrode assembly and increasing the energy density of the battery monomers. The expansion pressure of the battery monomers in the thickness direction is less than or equal to 2.4 MPa, which can limit the deformation of the electrode assembly during the cycle process, reduce the risk of the deformation of the separator of the electrode assembly and the risk of the increase of the local spacing between the positive electrode sheet and the negative electrode sheet, reduce the polarization, and improve the cycle performance of the battery monomers. The first current collecting component has a multi-layer structure, and each layer of the first current collecting component can transmit current. In this way, the first current collecting component can have a higher current-carrying area, thereby reducing the heat generation of the first current collecting component and improving the rapid charging capability and reliability of the battery.

[0008] The first busbar component is provided as a multi-layer structure under the premise that the overcurrent area meets the requirements, so that the thickness of each layer of the first busbar component can be reduced. The battery cell will swell during the cycle process, thereby stretching the layer of the first busbar component connected to the battery cell. The layer of the first busbar component has a smaller thickness, which is easy to deform to adapt to the swelling deformation of the battery cell, thereby reducing the risk of the connection between the battery cell and the first busbar component being pulled apart when the swelling pressure of the battery cell 10 is 0.5 MPa-2.4 MPa, and improving the reliability of the battery.

[0009] The first busbar component with a multi-layer structure can adapt to the swelling of the battery cell, and also take into account the overcurrent capacity and deformability of the first busbar component, thereby improving the reliability and rapid charging capability of the battery.

[0010] In some embodiments, the first busbar component includes a first busbar layer and a second busbar layer stacked and connected, and the first busbar layer is connected to at least two battery cells arranged in the thickness direction.

[0011] The first busbar layer and the second busbar layer can both transmit current, so that the first busbar component has a higher overcurrent area, thereby reducing the heat generation of the first busbar component and improving the rapid charging capability and reliability of the battery. Under the premise that the overcurrent area meets the requirements, the first busbar component is provided as a double-layer structure, so that the thickness requirement of the first busbar layer can be reduced. The battery cell will swell during the cycle process, thereby stretching the first busbar layer. The first busbar layer has a smaller thickness, which is easy to deform to adapt to the deformation of the battery cell, thereby reducing the risk of the connection between the battery cell and the first busbar layer being pulled apart, and improving the reliability of the battery.

[0012] In some embodiments, the battery cell includes an electrode terminal arranged in the shell, and the electrode terminal is electrically connected to the electrode assembly. The part of the first busbar layer that does not overlap the second busbar layer is connected to the electrode terminal. The second busbar layer can avoid the connection between the first busbar layer and the electrode terminal, thereby reducing the influence of the second busbar layer on the connection between the first busbar layer and the electrode terminal when the battery cell swells, reducing the risk of the connection between the electrode terminal and the first busbar layer being pulled apart, and improving the reliability of the battery.

[0013] In some embodiments, the first busbar layer is welded to the electrode terminal, and the welding area of the first busbar layer and the electrode terminal is greater than or equal to 60 mm 2 . The first busbar layer and the electrode terminal have a larger overcurrent area, thereby reducing the heat generation at the welding site, reducing the temperature rise of the first busbar layer during rapid charging, and improving the rapid charging capability of the battery.

[0014] In some embodiments, the first busbar component includes at least one bending portion connecting the first busbar layer and the second busbar layer. The bending portion can connect the first busbar layer and the second busbar layer and transmit current between the first busbar layer and the second busbar layer, thereby improving the overcurrent capacity of the first busbar component.

[0015] In some embodiments, the first busbar layer includes a first busbar portion and a second busbar portion arranged along the thickness direction and connected to different battery cells, and a first buffer portion connecting the first busbar portion and the second busbar portion. At least one of the first busbar portion and the second busbar portion is connected to the bending portion. During the cycle of the battery cell, the battery cell expands and exerts tension on the first busbar layer; the first buffer portion can release stress by deforming, thereby reducing the stress at the connection between the first busbar portion and the battery cell and the stress at the connection between the second busbar portion and the battery cell, and reducing the risk of failure of the connection between the first busbar layer and the battery cell.

[0016] In some embodiments, the bending portion is arranged away from the first buffer portion. The bending portion is not directly connected to the first buffer portion, thereby reducing the influence of the bending portion on the deformation of the first buffer portion and reducing the difficulty of deformation of the first buffer portion.

[0017] In some embodiments, the second busbar layer includes a first laminated portion laminated with the first busbar portion and connected through the at least one bending portion, a second laminated portion laminated with the second busbar portion and connected through the at least one bending portion, and a second buffer portion connecting the first laminated portion and the second laminated portion. In the laminating direction of the first busbar layer and the second busbar layer, the second buffer portion at least partially overlaps the first buffer portion.

[0018] During the cycle of the battery cell, the battery cell expands and exerts tension on the first busbar layer; both the first buffer portion and the second buffer portion can release stress by deforming, thereby reducing the risk of failure of the connection between the first busbar layer and the battery cell. The second buffer portion at least partially overlaps the first buffer portion, which can make the deformation areas of the first buffer portion and the second buffer portion close, thereby reducing the risk of interference between the first buffer portion and the second buffer portion and other parts when deforming.

[0019] In some embodiments, the second buffer portion and the first buffer portion are arranged in close contact, which can save space and improve the overcurrent capacity.

[0020] In some embodiments, the battery further comprises at least one second busbar component, the second busbar component is a single-layer structure and connects at least two battery monomers, the thickness of the second busbar component is greater than the thickness of the first busbar layer, and the thickness of the second busbar component is greater than the thickness of the second busbar layer. In the battery, the expansion amount of the battery monomers at different positions may be different. For the battery monomers with a smaller expansion amount, the second busbar component with a single-layer structure can be used; compared with the first busbar component, the second busbar component has a simple structure and is easy to manufacture, and the cost can be saved. The thickness of the second busbar component is greater than the thickness of the first busbar layer and the thickness of the second busbar layer, and the current-carrying capacity of the second busbar component can meet the requirements.

[0021] In some embodiments, the sum of the thickness of the first busbar layer and the thickness of the second busbar layer is equal to the thickness of the second busbar component, which can reduce the difference in current-carrying capacity between the first busbar component and the second busbar component, and improve the current consistency.

[0022] In some embodiments, among the plurality of battery monomers, the battery monomers located at the outermost side in the thickness direction are connected to the first busbar component. During the charging process, the expansion of the plurality of battery monomers may be superimposed in the thickness direction, which causes a larger displacement of the battery monomers located at the outermost side in the thickness direction; the first busbar component with a multi-layer structure is used to connect the battery monomers located at the outermost side, which can reduce the risk of connection failure between the first busbar component and the battery monomers.

[0023] In some embodiments, the thickness of the first busbar layer is 1 mm-2.5 mm, which can be selected as 1.2 mm-1.8 mm. According to the expansion pressure of the battery monomers, the thickness of the first busbar layer is selected in the embodiments of the present application, which can balance the current-carrying capacity of the first busbar layer and the deformability of the first busbar layer to a certain extent, thereby improving the rapid charging capability and reliability of the battery.

[0024] In some embodiments, the thickness of the second busbar layer is 1 mm-2.5 mm, which can be selected as 1.2 mm-1.8 mm.

[0025] In some embodiments, the volumetric energy density of the battery monomers is 390 Wh / L-450 Wh / L, and the thickness of the first busbar layer is less than or equal to 2.5 mm; or the volumetric energy density of the battery monomers is 450 Wh / L-480 Wh / L, and the thickness of the first busbar layer is less than or equal to 2.2 mm.

[0026] The expansion of the battery monomers is related to the volumetric energy density thereof, and the thickness of the first busbar layer is designed according to the volumetric energy density of the battery monomers in the present application, which can balance the current-carrying capacity of the first busbar layer and the deformability of the first busbar layer to a certain extent, thereby improving the rapid charging capability and reliability of the battery.

[0027] In some embodiments, the negative active material further comprises a silicon-based material. The mass content of silicon in the silicon-based material in the negative active material is 1% to 6%; the thickness of the first current-collecting layer is 1.2 mm to 2.2 mm, and the thickness of the second current-collecting layer is 1.2 mm to 2.2 mm.

[0028] By introducing the silicon-based material, the capacity of the negative electrode sheet can be improved, and the energy density of the battery cell can be improved. The introduction of the silicon-based material also increases the expansion of the negative electrode sheet during the cycle process. By designing the thickness of the first current-collecting layer and the thickness of the second current-collecting layer in combination with the content of silicon, the risk of connection failure of the first current-collecting layer and the battery cell caused by the introduction of the silicon-based material can be reduced, and the requirements for the overcurrent capacity of the first current-collecting part can be met.

[0029] In some embodiments, the first current-collecting layer comprises a first current-collecting part, a second current-collecting part, and a first buffer part connecting the first current-collecting part and the second current-collecting part. The first current-collecting part and the second current-collecting part are arranged in the thickness direction and connected to different battery cells. In the stacking direction of the first current-collecting layer and the second current-collecting layer, the first buffer part protrudes from the first current-collecting part and the second current-collecting part. The first current-collecting layer is provided with a recess at a position corresponding to the first buffer part. By providing the recess, the strength of the first buffer part can be reduced, facilitating the deformation of the first buffer part when the battery cell expands.

[0030] In some embodiments, the volumetric energy density of the battery cell is 390 Wh / L to 450 Wh / L, and the depth of the recess is 1.2 mm to 2.5 mm; or the volumetric energy density of the battery cell is 450 Wh / L to 480 Wh / L, and the depth of the recess is 1 mm to 2.2 mm.

[0031] The expansion of the battery cell is related to the volumetric energy density thereof. In the present application, the depth of the recess is designed according to the volumetric energy density of the battery cell, so as to balance the overcurrent capacity of the first buffer part and the deformability of the first buffer part to a certain extent, thereby improving the rapid charging capacity and reliability of the battery.

[0032] In some embodiments, the electrode assembly comprises two first surfaces and two second surfaces. The two first surfaces are oppositely arranged in the thickness direction, and the two second surfaces are oppositely arranged in a direction perpendicular to the thickness direction. The second surfaces connect the two first surfaces. The area of the first surface is greater than that of the second surface.

[0033] In some embodiments, the expansion pressure of the battery cell in the thickness direction is 1.5 MPa to 2.0 MPa. By limiting the expansion pressure of the battery cell in the thickness direction within the above range, the tensile force of the battery cell on the first current-collecting part during the cycle process of the battery cell can be reduced, the risk of connection failure of the battery cell and the first current-collecting part can be reduced, and the reliability of the battery can be improved.

[0034] In some embodiments, the single-side coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , and optionally 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 The single-side coating weight of the negative electrode film layer is related to the expansion of the battery monomer. By limiting the single-side coating weight of the negative electrode film layer in the above range, the energy density and expansion pressure of the battery monomer can be considered to a certain extent, the deformation of the battery monomer is reduced, and the risk of connection failure of the battery monomer and the first bus member is reduced.

[0035] In some embodiments, the compaction density of the negative electrode film layer at 100% SOC of the battery monomer is 1.15 g / cm 3 to 1.36 g / cm 3 , and optionally 1.25 g / cm 3 to 1.36 g / cm 3 The compaction density of the negative electrode film layer is related to the expansion of the battery monomer at 100% state of charge. By limiting the compaction density of the negative electrode film layer to 1.15 g / cm 3 to 1.36 g / cm 3 , the energy density and expansion pressure of the battery monomer can be considered to a certain extent, the deformation of the battery monomer is reduced, and the risk of connection failure of the battery monomer and the first bus member is reduced.

[0036] When the compaction density of the negative electrode film layer is in the above range, it is beneficial to improve the energy density of the battery monomer; and because the negative electrode active material in the negative electrode film layer is packed more tightly, the contact resistance between particles is smaller, which can reduce the resistance of the negative electrode sheet, thereby reducing heat generation.

[0037] When the compaction density of the negative electrode film layer is in the above range, the rapid charging capability of the battery monomer can be improved. A smaller compaction density of the negative electrode film layer can increase the porosity of the negative electrode sheet, slow down the expansion of the negative electrode sheet, and reduce the expansion pressure of the battery monomer.

[0038] In some embodiments, the porosity of the negative electrode sheet is 27%-40%. When the porosity of the negative electrode sheet is greater than or equal to 27%, it can provide space for impurities generated by side reactions of the negative electrode sheet, slow down the expansion of the negative electrode sheet, reduce the expansion pressure of the battery monomer, reduce the deformation of the battery monomer, improve the cycle performance of the battery monomer, and reduce the risk of connection failure of the battery monomer and the first bus member. When the porosity of the negative electrode sheet is less than or equal to 40%, the energy density of the battery monomer can be considered.

[0039] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. Artificial graphite and natural graphite have good electrical conductivity, which can reduce the heat generation of the negative electrode sheet during charging and improve the rapid charging performance of the battery cell.

[0040] In some embodiments, the negative electrode active material further includes a silicon-based material, and the mass content of silicon in the negative electrode active material is 0.3% to 10%, or 1% to 6%.

[0041] The introduction of the silicon-based material into the negative electrode sheet can not only improve the capacity but also increase the expansion of the negative electrode sheet. Therefore, the limitation of the mass content of silicon in the negative electrode active material within the above range can balance the energy density and expansion of the battery cell to some extent, reduce the deformation of the battery cell, improve the cycle performance of the battery cell, and reduce the risk of connection failure of the battery cell and the first bus member.

[0042] In some embodiments, the silicon-based material includes at least one of a silicon oxide compound and a silicon-carbon composite.

[0043] In some embodiments, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, and the second negative electrode film layer is arranged between the first negative electrode film layer and the negative electrode current collector. The negative electrode active material includes a first negative electrode active material arranged in the first negative electrode film layer and a second negative electrode active material arranged in the second negative electrode film layer, the first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and a silicon-based material. The first negative electrode film layer and the second negative electrode film layer can be differentially arranged, so as to balance the expansion and capacity of the negative electrode film layer to some extent; double-layer coating can construct the pore difference of the negative electrode film layer, reduce the ion transmission tortuosity, reduce the side reaction, and improve the rapid charging performance of the battery cell.

[0044] In some embodiments, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer is 3:7 to 7:3, or 4:6 to 6:4. By adjusting the thickness ratio of the first negative electrode film layer to the second negative electrode film layer, the gradient pore difference between the upper and lower layers can be further increased, the lithium ion transmission tortuosity can be reduced, and the rapid charging capacity of the battery cell can be improved.

[0045] In some embodiments, the thickness of the first negative electrode film layer is less than or equal to the thickness of the second negative electrode film layer, which can further improve the rapid charging capacity of the battery cell.

[0046] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material.

[0047] The difference in particle size between the first and second negative electrode active materials can improve the fast charging performance of the battery cell. During fast charging, the overpotential of the first negative electrode film is usually high, and the bottleneck of fast charging mainly lies in the first negative electrode film. However, in the embodiments of this application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transport path of ions, improve fast charging performance, and improve the problem of ion deposition on the surface of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film. During charging, the pores can absorb expansion, reduce the expansion of the negative electrode film, reduce the force exerted by the battery cell on the first busbar component, and reduce the risk of connection failure between the battery cell and the first busbar component.

[0048] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and optionally 7.8 μm-11.3 μm.

[0049] The volume average particle size Dv50 of the first negative electrode active material is set within the above-mentioned range. On the one hand, this can shorten the solid-phase transport path of lithium ions and improve fast charging performance. On the other hand, the material is less prone to agglomeration during the preparation process, which can improve the stability of the material. Furthermore, the first negative electrode active material within the above-mentioned volume average particle size range can cooperate with the second negative electrode active material, which is conducive to constructing a gradient porosity difference between the first negative electrode film and the second negative electrode film, reducing the tortuosity of lithium ion transport, and improving the fast charging performance of the battery cell.

[0050] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm, optionally 9.5 μm-14.6 μm. Setting the volume average particle size Dv of the second negative electrode active material within the above range can enrich the porosity of the second negative electrode film, which is beneficial to improving the fast charging capability of the battery cell and reducing the expansion of the negative electrode film during charging.

[0051] In some embodiments, the specific surface area of ​​the negative electrode active material is 0.5 m². 2 / g-3m 2 / g, optional 0.6m 2 / g-1.2m 2 / g. The specific surface area of ​​the negative electrode active material is limited to greater than or equal to 0.5m². 2 / g can improve the fast charging capability of individual battery cells; the specific surface area of ​​the negative electrode active material is limited to less than or equal to 3m². 2 / g can reduce side reactions of individual battery cells during storage and reduce expansion pressure.

[0052] In some embodiments, the single-side coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 - 370 mg / 1540 / mm 2 ; and can be 240 mg / 1540 mm 2 - 330 mg / 1540 mm 2 . When the single-side coating weight of the positive electrode film layer is set in the above range, the heat generation per unit area of the positive electrode sheet can be limited, and the energy density and the charge rate performance of the battery cell can be improved.

[0053] In some embodiments, the compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.50 g / cm 3 - 2.80 g / cm 3 ; and can be 2.55 g / cm 3 - 2.70 g / cm 3 . When the compaction density of the positive electrode film layer is in the above range, the energy density of the battery cell can be improved; and because the positive electrode active material in the positive electrode film layer is packed more closely, the contact resistance between particles is smaller, which can further reduce the resistance of the positive electrode sheet, thereby reducing the heat generation under fast charging.

[0054] In some embodiments, the porosity of the positive electrode sheet is 25%-32%. When the porosity of the positive electrode sheet is greater than or equal to 25%, space can be provided for impurities generated by side reactions of the positive electrode sheet, which can reduce the swelling pressure of the battery cell, reduce the deformation of the battery cell, improve the cycle performance of the battery cell, and reduce the risk of connection failure between the battery cell and the busbar component. When the porosity of the positive electrode sheet is less than or equal to 32%, the energy density of the battery cell can be considered to some extent.

[0055] In some embodiments, the thickness of the positive electrode sheet is 0.13 mm-0.2 mm. By using a positive electrode sheet with a smaller thickness, the ion migration path can be shortened, the ion migration rate can be improved, the heat generation of the battery cell can be reduced, and the fast charging performance of the battery cell can be improved.

[0056] In some embodiments, the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer is 0.05-0.3. By limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be greater than or equal to 0.05, the current-carrying capacity of the positive electrode current collector can be improved, the temperature rise of the positive electrode sheet can be reduced, and the fast charging performance of the battery cell can be improved; by limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be less than or equal to 0.3, the loss of the capacity of the positive electrode sheet can be reduced. By limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer in the above range, the fast charging performance and the energy density of the battery cell can be considered to some extent.

[0057] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1 μm≤Dv50≤2 μm, 0.4 μm≤Dv10≤0.7 μm. The particle size of the positive electrode active material is relatively small, the lithium ion has a shorter deintercalation lithium path in the positive electrode active material, and the heat generation is less; and the particle size of the positive electrode active material is not too small, so that the agglomeration can be reduced in the process of preparation, and the performance of the positive electrode active material is stable.

[0058] In some embodiments, the battery cell includes an electrolyte contained in the housing.

[0059] In some embodiments, the electrolyte has an electrical conductivity of 15 mS / cm to 20 mS / cm at room temperature. When the electrical conductivity of the electrolyte is in the above range, the migration rate of ions in the electrolyte is higher, thereby further reducing the internal resistance of the battery cell, reducing heat generation, and being able to improve the rapid charging performance of the battery cell.

[0060] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of a carbonate-based solvent and a carboxylate-based solvent. The combination of the organic solvent can improve the electrical conductivity and reduce the viscosity of the electrolyte, thereby improving the rapid charging performance of the battery.

[0061] In some embodiments, the carbonate-based solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0062] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 each independently includes an alkyl group with 1-5 carbon atoms or a halogenated alkyl group with 1-5 carbon atoms. The above chain carboxylate-based solvent has a high electrical conductivity, which is conducive to improving the rapid charging capability of the battery cell.

[0063] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes lithium bisfluorosulfonylimide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bisfluorosulfonylimide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L.

[0064] In some embodiments, the density ρ of the electrolyte at room temperature satisfies 1.05 g / mL≤ρ≤1.35 g / mL. When the density ρ of the electrolyte is in the above range, the migration rate of lithium ions in the electrolyte is higher, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and being able to improve the rapid charging performance of the battery cell.

[0065] In some embodiments, the electrode assembly has a size T in the thickness direction, the thickness of the single-layer negative electrode sheet is T1, and the number of layers of the negative electrode sheet stacked in the thickness direction is N.

[0066] T, T1 and N satisfy: 0.3≤(N×T1) / T≤0.5.

[0067] During the cycle of the battery cell, the thickness of the negative electrode sheet increases due to the irreversible side reaction, thereby causing the battery cell to swell; limiting (N×T1) / T in the above range can reduce the swelling of the battery cell and reduce the risk of failure of the connection between the battery cell and the busbar component.

[0068] In some embodiments, the charging time of the battery cell from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes.

[0069] In a second aspect, the embodiments of the present application provide a power utilization device, which comprises the battery provided by any of the embodiments of the first aspect, and the battery is used to provide electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0070] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by the drawings without creative labor.

[0071] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0072] FIG. 2 is a schematic diagram of a battery provided by some embodiments of the present application;

[0073] FIG. 3 is an exploded schematic diagram of a battery cell provided by some embodiments of the present application;

[0074] FIG. 4 is a schematic diagram of a battery provided by some embodiments of the present application;

[0075] FIG. 5 is an enlarged schematic diagram of the circular frame in FIG. 4;

[0076] FIG. 6 is a structural schematic diagram of a first busbar component shown in FIG. 5;

[0077] FIG. 7 is a connection schematic diagram of a battery cell and a first busbar component provided by some embodiments of the present application;

[0078] FIG. 8 is a schematic diagram of an electrode assembly described in FIG. 3;

[0079] FIG. 9 is a cross-sectional schematic diagram of the electrode assembly shown in FIG. 8;

[0080] FIG. 10 is a cross-sectional schematic diagram of a negative electrode sheet of a battery cell provided by some embodiments of the present application;

[0081] Fig. 11 is a cross-sectional view of a positive electrode tab of a battery cell according to some embodiments of the present application;

[0082] Fig. 12 is a cross-sectional view of a negative electrode tab of a battery cell according to some embodiments of the present application;

[0083] Fig. 13 is a top view of a battery according to some embodiments of the present application;

[0084] Fig. 14 is an enlarged view of the box in Fig. 13;

[0085] Fig. 15 is a structural view of a second bus member in Fig. 14.

[0086] Reference signs are explained as follows

[0087] 1, vehicle; 2, battery; 3, controller; 4, motor;

[0088] 10, battery cell; 100, battery cell row; 10a, large face; 10b, narrow face;

[0089] 11, electrode assembly; 111, positive electrode tab; 1111, positive electrode current collector; 1112, positive electrode film layer; 112, negative electrode tab; 1121, negative electrode current collector; 1122, negative electrode film layer; 11221, first negative electrode film layer; 11222, second negative electrode film layer; 112a, flat layer; 113, separator; 11a, main body portion; 11b, positive electrode tab; 11c, negative electrode tab; 11d, first surface; 11e, second surface; 11f, third surface;

[0090] 12, housing; 121, case; 122, end cap; 13, electrode terminal;

[0091] 20, box body; 21, limiting beam; 22, frame body; 23, support beam; 24, load bearing plate;

[0092] 30, bus member; 30a, first bus member; 30b, second bus member; 30c, third bus member; 31, first bus layer; 311, first bus portion; 312, second bus portion; 313, first buffer portion; 314, recess; 32, second bus layer; 321, first lamination portion; 322, second lamination portion; 323, second buffer portion; 33, bent portion;

[0093] X, thickness direction; Y, width direction; Z, height direction. DETAILED DESCRIPTION

[0094] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0095] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0096] In the present application, the phrase "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it mutually exclusive or alternative to other embodiments.

[0097] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0098] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0099] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed description of the same components is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length and width of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0100] "RANGES" disclosed herein are defined, for a given range by selecting: (1) a lower limit and (2) an upper limit, to define the range endpoints. Ranges can thus include the endpoint values or be excluded from the end values, as is normally perceived by one of ordinary skill in the art, and where the following claims appended hereto are drafted to particularize this application. Any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and a range of 80 to 110 are listed for a particular parameter, it is understood that a range of 60 to 110 and a range of 80 to 120 are also contemplated. Further, if a minimum range value of 1 and 2 are listed, and if a maximum range value of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, numerical ranges "a to b" are shorthand for describing all values that are within the range between "a" and "b", inclusive of "a" and "b", unless otherwise indicated. For example, a numerical range of "0 to 5" means that all real numbers between "0" and "5", inclusive of "0" and "5", have been listed herein. In addition, when a parameter is stated to be an integer > 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0101] "Plural" means two or more (including two).

[0102] "Parallel" includes not only instances of absolute parallel, but also instances of approximate parallel as commonly recognized in the engineering arts. "Perpendicular" includes not only instances of absolute perpendicular, but also instances of approximate perpendicular as commonly recognized in the engineering arts.

[0103] At present, from the development of market situation, the application of battery is more and more widely. The battery is not only applied to the energy storage power supply system of water power, fire power, wind power and solar power station, but also widely applied to electric bicycle, electric motorcycle, electric vehicle and other electric vehicles, and aerospace and other fields. With the continuous expansion of the application field of battery, the demand of its market is also increasing.

[0104] A battery generally refers to a single physical module including a plurality of battery cells to provide higher voltage and capacity. A battery cell is the smallest unit constituting a battery, and the plurality of battery cells are usually electrically connected through a busbar component. During the cycle process, an electrochemical reaction occurs inside the battery cell, causing the battery cell to swell. The swelling of the battery cell exerts a pulling force on the busbar component, triggering the risk of connection failure of the battery cell and the busbar component, affecting the reliability. In order to reduce the risk of connection failure of the battery cell and the busbar component, the thickness of the busbar component can be reduced so that the busbar component can release stress by deforming when the battery cell swells, reducing the risk of connection failure of the battery cell and the busbar component. However, reducing the thickness of the busbar component reduces the overcurrent area of the busbar component, that is, causes the busbar component to have high temperature rise and large resistance, affecting the rapid charging capability of the battery.

[0105] In view of this, the embodiments of the present application provide a battery, which reduces the risk of connection failure of the battery cell and the busbar component, increases the overcurrent area of the busbar component, and improves the rapid charging capability of the battery by reasonably designing the battery cell and the busbar component.

[0106] The battery described in the embodiments of the present application is suitable for a power consumption device using the battery. The power consumption device can be a device using the battery as a power source or various energy storage systems using the battery as an energy storage element. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, and the like. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, and an electric aircraft toy, and the like. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

[0107] The following embodiments take a vehicle as an example for convenience of description.

[0108] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application.

[0109] As shown in FIG. 1, a vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, the head or the tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power source of the vehicle 1.

[0110] The vehicle 1 can further include a controller 3 and a motor 4, and the controller 3 is used to control the battery 2 to supply power to the motor 4, for example, to meet the power demand of the vehicle 1 during starting, navigation and driving.

[0111] In some embodiments of the present application, the battery 2 can not only be used as an operating power source of the vehicle 1, but also be used as a driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0112] FIG. 2 is a schematic diagram of a battery according to some embodiments of the present application.

[0113] Referring to FIG. 2, in some embodiments, the battery 2 includes a case 20 and a plurality of battery cells 10 housed in the case 20.

[0114] The battery cell 10 can be a secondary battery, which refers to a battery cell that can be used continuously by activating the active material through charging after the battery cell is discharged.

[0115] By way of example, the battery cell 10 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium-metal battery cell, a sodium-metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, or the like.

[0116] By way of example, the battery cell 10 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, the prismatic battery cell including a square battery cell, a blade battery cell, a multi-prismatic battery cell, such as a hexagonal battery cell, or the like.

[0117] The plurality of battery cells 10 can be connected in series, in parallel, or in a mixed manner, the mixed manner referring to a manner in which the plurality of battery cells 10 are connected in series and in parallel. The plurality of battery cells 10 can be directly connected in series, in parallel, or in a mixed manner, and the plurality of battery cells 10 can be housed in the case 20 as a whole. Alternatively, the plurality of battery cells 10 can be connected in series, in parallel, or in a mixed manner to form a battery module, and the plurality of battery modules can be connected in series, in parallel, or in a mixed manner to form a whole, which can be housed in the case 20.

[0118] In some embodiments, the battery 2 includes a plurality of busbar components that electrically connect the plurality of battery cells 10.

[0119] In some embodiments, the case 20 can be a part of a chassis structure of a vehicle. For example, a part of the case 20 can be at least a part of a floor of the vehicle, or a part of the case 20 can be at least a part of a cross beam and a longitudinal beam of the vehicle.

[0120] FIG. 3 is an exploded schematic diagram of a battery cell according to some embodiments of the present application.

[0121] Referring to FIG. 3, in some embodiments, the battery cell 10 includes a housing 12 and an electrode assembly 11 housed in the housing 12.

[0122] The housing 12 is a hollow structure, and an accommodation space for accommodating the electrode assembly 11 and an electrolyte is formed inside the housing 12. The shape of the housing 12 can be determined according to the specific shape of the electrode assembly 11. For example, if the electrode assembly 11 is a cuboid structure, a cuboid housing can be selected.

[0123] As an example, the housing 12 includes a shell 121 having an opening and an end cap 122 for covering the opening.

[0124] The shell 121 is a component for cooperating with the end cap 122 to form an internal cavity of the battery cell 10, which can be used to house the electrode assembly 11, electrolyte, and other components.

[0125] The shell 121 and the end cap 122 can be separate components. As an example, the shell 121 can be provided with an opening, and the end cap 122 can be used to cover the opening to form the internal cavity of the battery cell 10.

[0126] The shell 121 can be in various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. In particular, the shape of the shell 121 can be determined according to the specific shape and size of the electrode assembly 11. The shell 121 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the present application does not make special limitations on this.

[0127] The end cap 122 can be shaped to cooperate with the shell 121. The material of the end cap 122 can be the same as or different from that of the shell 121. Alternatively, the end cap 122 can be made of a material with certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 122 is less likely to deform when subjected to extrusion and collision, and the battery cell 10 can have higher structural strength and improved reliability.

[0128] The end cap 122 can be connected to the shell 121 by welding, bonding, clamping, or other means.

[0129] The shell 121 can be open at one end or both ends. In some examples, the shell 121 can be open at one side, and the end cap 122 can be provided as one and cover the shell 121. In other examples, the shell 121 can be open at both ends, and the end cap 122 can be provided as two and cover the two openings of the shell 121.

[0130] The electrode assembly 11 is a component in which electrochemical reactions occur in the battery cell 10. The shell 121 can contain one or more electrode assemblies 11.

[0131] In some embodiments, the electrode assembly 11 includes a positive electrode sheet and a negative electrode sheet. During charging and discharging of the battery cell 10, active ions (such as lithium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet.

[0132] As an example, the portion of the positive electrode sheet and the portion of the negative electrode sheet having active material constitute a main body portion 11a of the electrode assembly 11, the portion of the positive electrode sheet not having active material constitutes a positive electrode tab 11b, and the portion of the negative electrode sheet not having active material constitutes a negative electrode tab 11c. The positive electrode tab 11b and the negative electrode tab 11c can be located at one end of the main body portion 11a or at both ends of the main body portion 11a.

[0133] In some embodiments, the electrode assembly 11 further comprises a separator film, which is arranged between the positive electrode sheet and the negative electrode sheet, and can prevent the positive and negative electrodes from short-circuiting while allowing active ions to pass through.

[0134] In some embodiments, the electrode assembly 11 has a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound to form the jelly-roll structure.

[0135] In some embodiments, the electrode assembly 11 has a stack structure.

[0136] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be arranged alternately.

[0137] As an example, a plurality of positive electrode sheets can be arranged, and the negative electrode sheet can be folded to form a plurality of folded segments arranged in layers.

[0138] As an example, the positive electrode sheet and the negative electrode sheet can be folded to form a plurality of folded segments arranged in layers.

[0139] As an example, a plurality of separator films can be arranged between any adjacent positive electrode sheets or negative electrode sheets.

[0140] As an example, the separator film can be arranged continuously and arranged between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0141] In some embodiments, the battery cell 10 further comprises an electrode terminal 13 arranged on the housing 12; the electrode terminal 13 can be used to electrically connect with the electrode assembly 11 to input or output electric energy.

[0142] In some embodiments, the electrode terminal 13 is electrically connected to the electrode tab. As an example, the electrode terminal 13 is two, and the two electrode terminals 13 are electrically connected to the positive electrode tab 11b and the negative electrode tab 11c, respectively.

[0143] FIG. 4 is a schematic diagram of a battery according to some embodiments of the present application; FIG. 5 is an enlarged schematic diagram of the circle in FIG. 4; FIG. 6 is a schematic diagram of a structure of a first current collecting component according to some embodiments of the present application; FIG. 7 is a schematic diagram of a connection between a battery cell and a first current collecting component according to some embodiments of the present application; FIG. 8 is a schematic diagram of an electrode assembly according to some embodiments of the present application; FIG. 9 is a cross-sectional schematic diagram of the electrode assembly according to some embodiments of the present application; FIG. 10 is a cross-sectional schematic diagram of a negative electrode sheet of a battery cell according to some embodiments of the present application; FIG. 11 is a cross-sectional schematic diagram of a positive electrode sheet of a battery cell according to some embodiments of the present application; and FIG. 12 is a cross-sectional schematic diagram of a negative electrode sheet of a battery cell according to some embodiments of the present application.

[0144] Referring to FIGS. 4-12, a battery according to some embodiments of the present application includes a plurality of battery cells 10 and a plurality of current collecting components 30 electrically connecting the plurality of battery cells 10.

[0145] The plurality of current collecting components 30 can connect the plurality of battery cells 10 in series, in parallel, or in a mixed connection.

[0146] The plurality of current collecting components 30 can have the same structure or different structures.

[0147] In some embodiments, the plurality of battery cells 10 are arranged along a thickness direction X of the battery cells 10. The battery cell 10 includes a housing 12 and an electrode assembly 11 contained in the housing 12. The battery cell 10 has an expansion pressure of 0.5 MPa-2.4 MPa in the thickness direction X.

[0148] In some embodiments, the battery includes a first current collecting component 30a electrically connecting at least two battery cells 10 arranged along the thickness direction X. The first current collecting component 30a has a multi-layer structure.

[0149] The electrode assembly 11 includes a positive electrode sheet 111, a negative electrode sheet 112, and a separator 113 between the positive electrode sheet 111 and the negative electrode sheet 112. The positive electrode sheet 111 includes a positive electrode current collector 1111 and a positive electrode film layer 1112 disposed on at least one side of the positive electrode current collector 1111, the positive electrode film layer 1112 including a positive electrode active material, the positive electrode active material including a lithium-containing phosphate with an olivine structure. The negative electrode sheet 112 includes a negative electrode current collector 1121 and a negative electrode film layer 1122 disposed on at least one side of the negative electrode current collector 1121, the negative electrode film layer 1122 including a negative electrode active material, the negative electrode active material including a carbon-based material.

[0150] The battery cells 10 can be arranged in one row or in multiple rows. For example, a row of battery cells 10 can form a battery cell row 100, the battery cell row 100 including at least two battery cells 10 arranged along the thickness direction X.

[0151] The battery cell 10 can include one or more electrode assemblies 11. Optionally, the electrode assemblies 11 are arranged along the thickness direction X.

[0152] Optionally, the battery cell 10 has an expansion pressure in the thickness direction X of 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa, or 2.4 MPa.

[0153] As an example, the expansion pressure of the battery cell 10 can be measured in the following manner:

[0154] Discharge the battery cell 10 at a constant current discharge rate of 1C to 2.0V at an ambient temperature of 45℃;

[0155] Clamp the battery cell 10 between two clamping plates, wherein the two clamping plates are respectively located on both sides of the battery cell 10 along the thickness direction X and cover the large face 10a (the large face 10a is the surface on one side of the battery cell 10 along the thickness direction X);

[0156] Charge the battery cell at a constant current charge rate of 0.8C to 3.8V at an ambient temperature of 45℃, detect and record the pressure exerted by the battery cell on the clamping plate;

[0157] Cycle the battery cell according to the above charge strategy and charge strategy until the battery cell is cycled to 70% SOH (i.e., the capacity retention rate of the battery cell = the discharge capacity of the battery cell / the nominal capacity of the battery cell = 70%), and record the maximum pressure exerted by the battery cell on the clamping plate;

[0158] Calculate the expansion pressure Q of the battery cell in the thickness direction as: maximum pressure / large face area.

[0159] In the embodiments of the present application, the negative electrode film layer 1122 can be arranged on only one side of the negative electrode current collector 1121, or can be arranged on both sides of the negative electrode current collector 1121.

[0160] Optionally, the negative electrode current collector 1121 has a negative electrode film layer 1122 on both surfaces opposite in the thickness direction of the negative electrode current collector 1121. The negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 can use the same negative electrode active material, or can use different negative electrode active materials; the thickness of the negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 can be the same, or can be different.

[0161] Exemplarily, the negative current collector 1121 can adopt a metal foil or a composite current collector. As an example of the metal foil, at least one of a copper foil, a copper alloy foil, a nickel foil, a nickel alloy foil, a titanium foil, a titanium alloy foil, a silver foil, and a silver alloy foil can be adopted. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer can include at least one of copper, a copper alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0162] The negative active material includes a carbon-based material. The carbon-based material has high cycle stability, and can improve the cycle performance of the battery cell.

[0163] The positive current collector 1111 has two surfaces opposite in the thickness direction thereof, and the positive film layer 1112 is disposed on either or both of the two opposite surfaces of the positive current collector 1111.

[0164] Exemplarily, the positive current collector 1111 can adopt a metal foil or a composite current collector. As an example of the metal foil, at least one of an aluminum foil, an aluminum alloy foil, a nickel foil, a nickel alloy foil, a titanium foil, a titanium alloy foil, a silver foil, and a silver alloy foil can be adopted. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer can include at least one of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0165] The lithium-containing phosphate has high cycle stability, and the use of the lithium-containing phosphate as the positive active material can improve the cycle degradation of the battery cell 10 caused by excessively high temperature rise during fast charging.

[0166] The plurality of bus members 30 can all be the first bus member 30a, or some of the plurality of bus members 30 can be the first bus member 30a.

[0167] The expansion pressure of the battery cell 10 is related to the compactness of the electrode assembly 11. The embodiments of the present application can allow the battery cell 10 to have an expansion pressure greater than or equal to 0.5 MPa in the thickness direction X, thereby improving the compactness of the electrode assembly 11 and improving the energy density of the battery cell 10. The expansion pressure of the battery cell 10 in the thickness direction X is less than or equal to 2.4 MPa, which can limit the deformation of the electrode assembly 11 during the cycle process, reduce the risk of crease deformation of the separator of the electrode assembly 11 and the risk of local increase in the distance between the positive and negative electrode sheets, reduce polarization, and improve the cycle performance of the battery cell 10.

[0168] The first busbar component 30a has a multi-layer structure, and each layer structure of the first busbar component 30a can transmit current, so that the first busbar component 30a has a higher current-carrying area, thereby reducing the heat generation of the first busbar component 30a and improving the rapid charging capability of the battery 2.

[0169] Under the premise that the current-carrying area meets the requirements, the first busbar component 30a is provided as a multi-layer structure, which can reduce the thickness of each layer structure of the first busbar component 30a. The battery cell 10 will expand during the cycle process, thereby stretching the layer structure of the first busbar component 30a connected to the battery cell 10. The layer structure of the first busbar component 30a has a smaller thickness, which is easy to deform to adapt to the expansion deformation of the battery cell 10, thereby reducing the risk of tearing at the connection between the battery cell 10 and the first busbar component 30a when the expansion pressure of the battery cell 10 is 0.5 MPa-2.4 MPa, and improving the reliability of the battery 2.

[0170] The embodiments of the present application adopt the first busbar component with a multi-layer structure, which can adapt to the expansion of the battery cell and take into account the current-carrying capability and deformability of the first busbar component, thereby improving the reliability and rapid charging capability of the battery.

[0171] In some embodiments, the first busbar component 30a includes a first busbar layer 31 and a second busbar layer 32 stacked and connected, and the first busbar layer 31 is connected to at least two battery cells 10 arranged in the thickness direction X.

[0172] The first busbar layer 31 and the second busbar layer 32 can be an integrally formed structure. Alternatively, the first busbar layer 31 and the second busbar layer 32 can also be independently formed and connected by welding or other means.

[0173] The first busbar layer 31 and the second busbar layer 32 can both transmit current, so that the first busbar component 30a has a high current-carrying area, thereby reducing the heat generation of the first busbar component 30a and improving the rapid charging capability and reliability of the battery. Under the premise that the current-carrying area meets the requirements, the first busbar component 30a is provided in a double-layer structure, which can reduce the requirement for the thickness of the first busbar layer 31. The battery cell 10 will swell during the cycle process, thereby stretching the first busbar layer 31. The first busbar layer 31 has a small thickness and is easy to deform to adapt to the deformation of the battery cell 10, thereby reducing the risk of the connection between the battery cell 10 and the first busbar layer 31 being pulled apart and improving the reliability of the battery 2.

[0174] In some embodiments, the battery cell 10 includes an electrode terminal 13 disposed on the shell 12, and the electrode terminal 13 is electrically connected to the electrode assembly 11. The first busbar layer 31 is connected to the electrode terminal 13 of the battery cell 10.

[0175] Optionally, the first busbar layer 31 is welded to the electrode terminal 13.

[0176] In some embodiments, the part of the first busbar layer 31 that does not overlap the second busbar layer 32 is connected to the electrode terminal 13.

[0177] The second busbar layer 32 can avoid the connection between the first busbar layer 31 and the electrode terminal 13, thereby reducing the influence of the second busbar layer 32 on the connection between the first busbar layer 31 and the electrode terminal 13 when the battery cell swells, reducing the risk of the connection between the electrode terminal 13 and the first busbar layer 31 being pulled apart, and improving the reliability of the battery 2. In addition, when the battery cell 10 and the first busbar component 30a are assembled, the second busbar layer 32 does not cover the area of the first busbar layer 31 for connecting with the electrode terminal 13, so that the assembly difficulty can be reduced.

[0178] In some embodiments, the first busbar layer 31 is welded to the electrode terminal 13, and the welding area of the first busbar layer 31 and the electrode terminal 13 is greater than or equal to 60mm 2 .

[0179] Illustratively, the first busbar layer 31 is welded to the electrode terminal 13 and forms a welding mark; the welding area can be the area of the projection of the welding mark along the thickness direction of the first busbar layer. Optionally, the welding mark is a circular ring, and the inner radius and the outer radius of the welding mark are R1 and R2 respectively, so that the welding area is π×(R2 2 -R1 2 ).

[0180] Illustratively, the welding area of the first busbar layer 31 and the electrode terminal 13 is 60mm 2 , 70mm 2 , 80mm 2 , 90mm2 100mm 2 110mm 2 or 120mm 2 .

[0181] The embodiments of the present application can make the first busbar layer 31 and the electrode terminal 13 have a larger flow area, thereby reducing the heat generation at the welding position, reducing the temperature rise of the first busbar layer 31 during rapid charging, and improving the rapid charging capability of the battery.

[0182] In some embodiments, the second busbar layer 32 does not cover the welding position.

[0183] In some embodiments, the second busbar layer 32 partially overlaps with the electrode terminal 13 in the stacking direction of the first busbar layer 31 and the second busbar layer 32, which can shorten the conductive path between the second busbar layer 32 and the electrode terminal 13, thereby reducing the resistance and reducing the heat generation.

[0184] In some embodiments, the first busbar layer 31 and the second busbar layer 32 are stacked along the height direction Z of the battery monomer 10. In other words, the stacking direction of the first busbar layer 31 and the second busbar layer 32 is parallel to the height direction Z. Exemplarily, the height direction Z is perpendicular to the thickness direction X.

[0185] In some embodiments, the second busbar layer 32 can be arranged on the side of the first busbar layer 31 facing the battery monomer 10, or on the side of the first busbar layer 31 away from the battery monomer 10.

[0186] In some embodiments, the first busbar component 30a includes at least one bending portion 33 connecting the first busbar layer 31 and the second busbar layer 32.

[0187] The bending portion 33 can be one or more.

[0188] The bending portion 33 can connect the first busbar layer 31 and the second busbar layer 32 and transmit current between the first busbar layer 31 and the second busbar layer 32, thereby improving the current carrying capacity of the first busbar component 30a.

[0189] In some embodiments, the first busbar layer 31 includes a first busbar portion 311, a second busbar portion 312, and a first buffer portion 313, the first busbar portion 311 and the second busbar portion 312 are arranged along the thickness direction X and connected to different battery monomers 10, and the first buffer portion 313 connects the first busbar portion 311 and the second busbar portion 312. At least one of the first busbar portion 311 and the second busbar portion 312 is connected to the bending portion 33.

[0190] The first busbar portion 311 can be connected to the electrode terminal 13 of one battery cell 10, or can be simultaneously connected to the electrode terminals 13 of at least two battery cells 10. The second busbar portion 312 can be connected to the electrode terminal 13 of one battery cell 10, or can be simultaneously connected to the electrode terminals 13 of at least two battery cells 10.

[0191] During the cycle of the battery cell 10, the battery cell 10 expands and exerts a pulling force on the first busbar layer 31; the first buffer portion 313 can release stress by deforming, thereby reducing the stress at the connection between the first busbar portion 311 and the battery cell 10 and the stress at the connection between the second busbar portion 312 and the battery cell 10, and reducing the risk of failure of the connection between the first busbar layer 31 and the battery cell 10.

[0192] In some embodiments, the bending portion 33 is arranged away from the first buffer portion 313. The bending portion 33 is not directly connected to the first buffer portion 313, thereby reducing the influence of the deformation of the bending portion 33 on the first buffer portion 313 and reducing the difficulty of deformation of the first buffer portion 313.

[0193] In some embodiments, the first busbar layer 31 and the second busbar layer 32 are arranged in abutment. Optionally, in addition to the bending portion 33, there is no other fixed connection relationship between the first busbar layer 31 and the second busbar layer 32. Alternatively, a conductive adhesive can be provided between the first busbar layer 31 and the second busbar layer 32.

[0194] In some embodiments, the first busbar portion 311 is located on the upper side of the electrode terminal 13 of the battery cell 10, and the second busbar portion 312 is located on the upper side of the electrode terminal 13 of the battery cell 10.

[0195] In some embodiments, the first buffer portion 313 comprises an arch-shaped structure.

[0196] In some embodiments, the first busbar portion 311 is connected to the second busbar layer 32 through at least one bending portion 33, and the second busbar portion 312 is connected to the second busbar layer 32 through at least one bending portion 33.

[0197] In some embodiments, the second busbar layer 32 comprises a first laminated portion 321, a second laminated portion 322, and a second buffer portion 323. The first laminated portion 321 is laminated with the first busbar portion 311 and is connected through at least one bending portion 33, and the second laminated portion 322 is laminated with the second busbar portion 312 and is connected through at least one bending portion 33. The second buffer portion 323 connects the first laminated portion 321 and the second laminated portion 322. In the laminating direction of the first busbar layer 31 and the second busbar layer 32, the second buffer portion 323 at least partially overlaps the first buffer portion 313.

[0198] During the cycle of the battery cell 10, the battery cell 10 expands and exerts a pulling force on the first busbar layer 31; the first buffer part 313 and the second buffer part 323 can both release stress by deforming, thereby reducing the risk of connection failure of the first busbar layer 31 and the battery cell 10. The second buffer part 323 at least partially overlaps the first buffer part 313, so that the deformation areas of the first buffer part 313 and the second buffer part 323 are close to each other, thereby reducing the risk of interference of the first buffer part 313 and the second buffer part 323 with other parts when deforming.

[0199] In some embodiments, the second buffer part 323 and the first buffer part 313 are arranged in abutment. The embodiments of the application can save space and improve the overcurrent capacity.

[0200] In some embodiments, the outer surface of the battery cell 10 includes two large faces 10a and two narrow faces 10b, the two large faces 10a are arranged opposite to each other along the thickness direction X, the two narrow faces 10b are arranged opposite to each other along the width direction Y of the battery cell, and the two ends of the large face 10a along the width direction Y are connected to the two narrow faces 10b. The area of the large face 10a is larger than the area of the narrow face 10b.

[0201] In some embodiments, the thickness direction X, the width direction Y and the height direction Z are perpendicular to each other.

[0202] In some embodiments, the plurality of battery cell columns 100 are arranged along the width direction Y.

[0203] In some embodiments, the expansion pressure of the battery cell 10 in the thickness direction X is 1.5-2.0 MPa.

[0204] The embodiments of the application limit the expansion pressure of the battery cell 10 in the thickness direction X to 1.5-2.0 MPa, so as to reduce the pulling force of the battery cell on the first busbar part during the cycle of the battery cell, reduce the risk of connection failure of the battery cell and the first busbar part, and improve the reliability of the battery.

[0205] In some embodiments, the thickness of the first busbar layer 31 is 1-2.5 mm, and optionally 1.2-1.8 mm.

[0206] For example, the thickness of the first busbar layer 31 is 1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm or 2.5 mm.

[0207] The thickness of the first busbar layer 31 is selected according to the swelling pressure of the battery cell 10, so that the overcurrent capacity of the first busbar layer 31 and the deformability of the first busbar layer 31 are considered to some extent, thereby improving the rapid charging capability and reliability of the battery 2.

[0208] In some embodiments, the thickness of the second busbar layer 32 is 1 mm-2.5 mm, which can be 1.2 mm-1.8 mm. For example, the thickness of the second busbar layer 32 is 1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm or 2.5 mm.

[0209] The thickness of the second busbar layer 32 can be selected according to the thickness of the first busbar layer 31 and the overcurrent capacity of the battery to the first busbar component. For example, when the thickness of the first busbar layer 31 is small, the second busbar layer 32 can have a thickness greater than that of the first busbar layer 31 to improve the overcurrent capacity of the first busbar component.

[0210] In some embodiments, the volumetric energy density of the battery cell 10 is 390 Wh / L-450 Wh / L, and the thickness of the first busbar layer 31 is less than or equal to 2.5 mm.

[0211] The volumetric energy density of the battery cell 10 is the meaning known in the art, which can be detected by using the devices and methods known in the art.

[0212] The swelling of the battery cell 10 is related to its volumetric energy density, and the thickness of the first busbar layer 31 is designed according to the volumetric energy density of the battery cell 10, so that the overcurrent capacity of the first busbar layer 31 and the deformability of the first busbar layer 31 are considered to some extent, thereby improving the rapid charging capability and reliability of the battery 2.

[0213] In some embodiments, the volumetric energy density of the battery cell 10 is 450 Wh / L-480 Wh / L, and the thickness of the first busbar layer 31 is less than or equal to 2.2 mm.

[0214] The swelling of the battery cell 10 is related to its volumetric energy density, and for the battery 2 using a battery cell 10 with high volumetric energy density, the thickness of the first busbar layer 31 needs to be reduced. The thickness of the first busbar layer 31 is designed according to the volumetric energy density of the battery cell 10, so that the overcurrent capacity of the first busbar layer 31 and the deformability of the first busbar layer 31 are considered to some extent, thereby improving the rapid charging capability and reliability of the battery 2.

[0215] In some embodiments, the negative active material further comprises a silicon-based material. The mass content of silicon in the silicon-based material in the negative active material is 1%-6%; the thickness of the first current-collecting layer 31 is 1.2mm-2.2mm, and the thickness of the second current-collecting layer 32 is 1.2mm-2.2mm.

[0216] For example, the mass content of silicon in the silicon-based material in the negative active material is 1%, 2%, 3%, 4%, 5%, or 6%. For example, the thickness of the first current-collecting layer 31 is 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, or 2.2mm. For example, the thickness of the second current-collecting layer 32 is 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, or 2.2mm.

[0217] By introducing the silicon-based material, the capacity of the negative electrode sheet 112 can be improved, and the energy density of the battery monomer 10 can be improved. The introduction of the silicon-based material also increases the expansion of the negative electrode sheet 112 during the cycle process. By designing the thickness of the first current-collecting layer 31 and the thickness of the second current-collecting layer 32 in combination with the content of silicon, the risk of failure of the connection between the first current-collecting layer 31 and the battery monomer 10 caused by the introduction of the silicon-based material can be reduced, and the requirement for the overcurrent capacity of the first current-collecting member 30a can be met.

[0218] In some embodiments, the first current-collecting layer 31 comprises a first current-collecting part 311, a second current-collecting part 312, and a first buffer part 313 connecting the first current-collecting part 311 and the second current-collecting part 312. The first current-collecting part 311 and the second current-collecting part 312 are arranged along the thickness direction X and connected to different battery monomers 10. In the stacking direction of the first current-collecting layer 31 and the second current-collecting layer 32, the first buffer part 313 protrudes from the first current-collecting part 311 and the second current-collecting part 312. The first current-collecting layer 31 is provided with a recess 314 at a position corresponding to the first buffer part 313.

[0219] By providing the recess 314, the strength of the first buffer part 313 can be reduced, and the deformation of the first buffer part 313 when the battery monomer 10 expands can be facilitated.

[0220] In some embodiments, the volumetric energy density of the battery monomer 10 is 390Wh / L-450Wh / L, and the depth H2 of the recess 314 is 1.2mm-2.5mm.

[0221] The expansion of the battery cell 10 is related to the volumetric energy density thereof. The depth of the recess 314 is designed according to the volumetric energy density of the battery cell 10 in the application, so as to balance the overcurrent capacity of the first buffer part 313 and the deformability of the first buffer part 313 to a certain extent, thereby improving the rapid charging capacity and reliability of the battery 2.

[0222] In some embodiments, the volumetric energy density of the battery cell 10 is 450-480 Wh / L, and the depth of the recess 314 is 1-2.2 mm.

[0223] The expansion of the battery cell 10 is related to the volumetric energy density thereof. For the battery 2 using the battery cell 10 with high volumetric energy density, it is necessary to reduce the difficulty of deformation of the first buffer part 313. The depth of the recess 314 is designed according to the volumetric energy density of the battery cell 10 in the application, so as to balance the overcurrent capacity of the first buffer part 313 and the deformability of the first buffer part 313 to a certain extent, thereby improving the rapid charging capacity and reliability of the battery 2.

[0224] In some embodiments, the battery 2 further comprises a box body 20. The box body 20 is used to accommodate a plurality of battery cells 10. The box body 20 comprises at least two limiting beams 21, and adjacent two limiting beams 21 are arranged along the thickness direction X, and a plurality of battery cell columns 100 are arranged between adjacent limiting beams 21.

[0225] For example, at least one battery cell column 100 is arranged between any adjacent two limiting beams 21.

[0226] The limiting beam 21 can be used to limit the expansion deformation of the battery cell 10 in the thickness direction X. The limiting beam 21 can directly abut the battery cell 10 in the thickness direction X; alternatively, other components can be arranged between the limiting beam 21 and the battery cell 10, i.e., the limiting beam 21 limits the expansion of the battery cell 10 through the components.

[0227] The limiting beam 21 can limit the expansion of the battery cell 10 in the cycle process of the battery, thereby reducing the pulling force exerted by the battery cell 10 on the first bus member 30a, reducing the risk of connection failure between the battery cell 10 and the first bus member 30a, and improving the reliability of the battery.

[0228] In some embodiments, the electrode assembly 11 comprises two first surfaces 11d and two second surfaces 11e, the two first surfaces 11d are oppositely arranged along the thickness direction X, the two second surfaces 11e are oppositely arranged along a direction perpendicular to the thickness direction X, and the second surface 11e connects the two first surfaces 11d. The area of the first surface 11d is greater than that of the second surface 11e.

[0229] By positioning the larger first surface 11d opposite the limiting beam 21 along the thickness direction X, the force-bearing area of ​​the limiting beam 21 can be increased and the deformation of the limiting beam 21 can be reduced when the electrode assembly 11 expands.

[0230] In some embodiments, the limiting beam 21 extends along the width direction Y.

[0231] In some embodiments, the two second surfaces 11e are arranged opposite each other along the width direction Y.

[0232] In some embodiments, the main body 11a includes two first surfaces 11d, two second surfaces 11e, and two third surfaces 11f; the two third surfaces 11f are located at both ends of the battery cell 10 along the height direction Z, and the third surfaces 11f are connected to the two first surfaces 11d and the two second surfaces 11e.

[0233] The positive electrode tab 11b and the negative electrode tab 11c extend from the same third surface 11f, or the positive electrode tab 11b and the negative electrode tab 11c extend from two different third surfaces 11f.

[0234] In some embodiments, at least a portion of the second surface 11e is arc-shaped. Optionally, the electrode assembly 11 is a wound structure, and the second surface 11e is an arc surface.

[0235] In some embodiments, the large surface 10a is parallel to the first surface 11d.

[0236] In some embodiments, the battery cell 10 is a prismatic battery cell. Optionally, the narrow face 10b is perpendicular to the large face 10a.

[0237] In some embodiments, a portion of the negative current collector 1121 is not covered by the negative electrode film layer 1122; the portion of the negative current collector 1121 not covered by the negative electrode film layer 1122 may be used to form a negative electrode tab 11c.

[0238] In some embodiments, the thickness of the negative electrode current collector 1121 is 4 μm to 6 μm. Exemplarily, the thickness of the negative electrode current collector 1121 is 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, or any range of two of the above values.

[0239] In some embodiments, the compaction density of the negative electrode film 1122 at 100% SOC of the battery cell is 1.15 g / cm³. 3 Up to 1.36 g / cm 3 For example, when the battery cell 10 is at 100% charge, the compaction density of the negative electrode film layer 1122 is 1.15 g / cm³. 3 1.18 g / cm 3 1.20g / cm 3 1.22g / cm3 1.25 g / cm 3 1.28 g / cm 3 1.3 g / cm 3 1.32 g / cm 3 1.35 g / cm 3 1.36 g / cm 3 or a range between any two of the above values.

[0240] For example, 100% SOC (state of charge) and 0% SOC are defined as follows:

[0241] The battery cell is charged to the upper limit voltage of battery charge at a constant current charging rate of 0.33C, and then charged to 0.05C at a constant voltage, corresponding to the state of 100% SOC of the battery cell; the battery cell is discharged to the cut-off voltage at a constant current discharge rate of 0.33C, corresponding to the state of 0% SOC of the battery cell. For example, the upper limit voltage of battery charge can be 3.8V; the cut-off voltage of battery discharge can be 2.0V.

[0242] For example, the compaction density of the negative electrode film layer of the battery cell at 100% state of charge is the meaning known in the art, that is, the negative electrode film layer of the battery cell at 100% SOC is disassembled to obtain a negative electrode sheet, and the compaction density of the negative electrode film layer is measured; for example, a single-sided coated negative electrode sheet (if it is a double-sided coated negative electrode sheet, the negative electrode film layer on one side can be wiped off first) is punched into a small round piece with an area of S1, weighed, and recorded as M1, and its thickness H1 is measured. Then the negative electrode film layer of the above weighed negative electrode sheet is wiped off, the weight of the negative electrode current collector is weighed and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the negative electrode film layer = (the weight of the negative electrode sheet M1 - the weight of the negative electrode current collector M0) / S1, the thickness of the negative electrode film layer = the thickness of the negative electrode sheet H1 - the thickness of the negative electrode current collector H0, and the compaction density of the negative electrode film layer = the single-sided coating weight of the negative electrode film layer / the thickness of the negative electrode film layer.

[0243] The compaction density of the negative electrode film layer 1122 is related to the expansion of the battery cell 10 at 100% state of charge, and the compaction density of the negative electrode film layer 1122 is limited to 1.15 g / cm 3 1.36 g / cm 3 , which can balance the energy density and expansion pressure of the battery cell 10 to a certain extent, reduce the deformation of the battery cell 10, and reduce the risk of connection failure of the battery cell 10 and the busbar component.

[0244] The compaction density of the negative electrode film layer 1122 in the above range is beneficial to improve the energy density of the battery monomer 10; and since the negative electrode active material in the negative electrode film layer 1122 is packed more closely, the contact resistance between particles is smaller, which can reduce the resistance of the negative electrode sheet 112, thereby reducing the heat generation.

[0245] The compaction density of the negative electrode film layer 1122 in the above range can improve the rapid charging capability of the battery monomer 10. The compaction density of the negative electrode film layer 1122 is smaller, which can increase the porosity of the negative electrode sheet 112, slow down the expansion of the negative electrode sheet, and reduce the expansion pressure of the battery monomer 10.

[0246] In some embodiments, the compaction density of the negative electrode film layer 1122 at 100% SOC of the battery monomer is 1.25 g / cm 3 to 1.36 g / cm 3 , which can improve the energy density of the battery monomer 10.

[0247] In some embodiments, the single-sided coating weight of the negative electrode film layer 1122 is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 . For example, the single-sided coating weight of the negative electrode film layer 1122 is 90 mg / 1540.25 mm 2 , 92 mg / 1540.25 mm 2 , 95 mg / 1540.25 mm 2 , 96 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 102 mg / 1540.25 mm 2 , 104 mg / 1540.25 mm 2 , 105 mg / 1540.25 mm 2 , 108 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 112 mg / 1540.25 mm 2 , 114 mg / 1540.25 mm 2 , 115 mg / 1540.25 mm 2 , 116 mg / 1540.25 mm 2 , 118 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 122 mg / 1540.25 mm 2 , 125 mg / 1540.25 mm 2 , 128 mg / 1540.25 mm 2, 130 mg / 1540.25 mm 2 , 132 mg / 1540.25 mm 2 , 135 mg / 1540.25 mm 2 , 137 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 142 mg / 1540.25 mm 2 , 145 mg / 1540.25 mm 2 , 148 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 152 mg / 1540.25 mm 2 , 155 mg / 1540.25 mm 2 , 160 mg / 1540.25 mm 2 , 165 mg / 1540.25 mm 2 , 167 mg / 1540.25 mm 2 , 170 mg / 1540.25 mm 2 or a range between any two of the above values.

[0248] The single-side coating weight of the negative electrode film layer 1122 is related to the expansion of the negative electrode film layer. The single-side coating weight of the negative electrode film layer 1122 is limited to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , which can balance the energy density and the expansion pressure of the battery monomer 10 to a certain extent, reduce the deformation of the battery monomer 10, and reduce the risk of connection failure between the battery monomer 10 and the busbar component.

[0249] In addition, limiting the single-side coating weight of the negative electrode film layer 1122 to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 can also limit the heat generation per unit area of the negative electrode sheet 112, and reduce the temperature rise of the battery monomer 10, especially during rapid charging.

[0250] In some embodiments, the single-side coating weight of the negative electrode film layer 1122 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 , to further balance the energy density and the expansion pressure of the battery monomer 10.

[0251] In some embodiments, the porosity of the negative electrode sheet 112 is 27% to 40%. For example, the porosity of the negative electrode sheet 112 can be 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%.

[0252] The porosity of the negative electrode sheet can be a percentage of a pore volume in the negative electrode sheet to a total volume of the negative electrode sheet. For example, a double-sided coated negative electrode sheet is taken when the battery cell is at 0% state of charge, and the porosity of the negative electrode sheet is measured by a true density instrument AccuPyc II 1340 according to the national standard GB / T 24586-2009.

[0253] In the embodiments of the present application, the porosity of the negative electrode sheet 112 is greater than or equal to 27%, which can provide space for impurities generated by side reactions of the negative electrode sheet 112, slow down the expansion of the negative electrode sheet 112, reduce the expansion pressure of the battery cell 10, reduce the deformation of the battery cell 10, improve the cycle performance of the battery cell 10, and reduce the risk of connection failure of the battery cell and the busbar component. The porosity of the negative electrode sheet 112 is less than or equal to 40%, which can balance the energy density of the battery cell 10.

[0254] In some embodiments, the carbon-based material includes graphite particles, and the graphitization degree of the graphite particles is 92.0% to 94.5%. For example, the graphitization degree of the graphite particles is 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5%, or a range composed of any two of the above values.

[0255] When the graphitization degree of the graphite particles is in the above range, the conductive performance of the graphite particles is relatively excellent, which can reduce the heat generation of the negative electrode sheet 112 and the battery cell 10, and improve the rapid charging performance of the battery cell 10.

[0256] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. The conductive performance of the artificial graphite and the natural graphite is good, which can reduce the heat generation of the negative electrode sheet 112 during charging and improve the rapid charging performance of the battery cell 10.

[0257] In some embodiments, the negative electrode active material further includes a silicon-based material. The introduction of the silicon-based material can improve the capacity of the negative electrode active material and increase the energy density of the battery cell 10.

[0258] In some embodiments, the mass content of the silicon element in the silicon-based material in the negative electrode active material is 0.3% to 10%, and can be 1% to 6% optionally. Illustratively, the mass content of the silicon element in the negative electrode active material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or a range between any two of the above values.

[0259] The introduction of the silicon-based material in the negative electrode sheet 112 can not only improve the capacity, but also increase the expansion of the negative electrode sheet 112. Therefore, the mass content of the silicon element in the negative electrode active material is limited to 0.3% to 10%, which can balance the energy density and expansion of the battery monomer 10 to a certain extent, reduce the deformation of the battery monomer 10, reduce the risk of connection failure between the battery monomer and the busbar component, and improve the cycle performance of the battery monomer 10.

[0260] The qualitative and quantitative detection of each substance or element in the present application can be carried out by using suitable equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc., and those skilled in the art can also adaptively change certain detection steps / instrument parameters from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used jointly for qualitative or quantitative determination.

[0261] For example, the silicon-based material can be subjected to X-ray powder diffraction test and qualitative analysis by combining JIS / K0131-1996 X-ray Diffraction Analysis Method General Rules for the negative electrode sheet or the negative electrode active material.

[0262] In some embodiments, the silicon-based material can include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.

[0263] In some embodiments, the silicon-based material includes at least one of silicon oxide and silicon-carbon composite.

[0264] In some embodiments, the negative electrode active material can include at least one of tin-based material and lithium titanate in addition to the carbon-based material and the optional silicon-based material. The tin-based material can include at least one of elemental tin, tin oxide, and tin alloy material.

[0265] In some embodiments, the negative electrode film layer 1122 in the embodiments of the present application includes at least one film layer, in other words, the negative electrode film layer 1122 can adopt a single-layer film layer or at least two film layers. Optionally, the negative electrode film layer 1122 includes at least two film layers.

[0266] In the case where the negative electrode film layer 1122 adopts a single-layer film layer, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally further includes a silicon-based material. In the case where a single-layer film layer is adopted, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm to 13.5 μm. Illustratively, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, or a range formed by any two of the above values.

[0267] In the case where the negative electrode film layer 1122 adopts at least two film layers, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally further includes a silicon-based material, which can be located in one of the at least two film layers or in at least two of the at least two film layers. The negative electrode film layer 1122 can include two film layers, three film layers, four film layers, or even more film layers.

[0268] In some embodiments, the negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222, and the second negative electrode film layer 11222 is arranged between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material arranged in the first negative electrode film layer 11221 and a second negative electrode active material arranged in the second negative electrode film layer 11222, and the first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and a silicon-based material.

[0269] The interface of the first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be regular or irregular; and optionally irregular.

[0270] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be differentially arranged, so as to take into account the expansion and capacity of the negative electrode film layer 1122 to some extent; double-layer coating can construct the pore difference of the negative electrode film layer 1122, reduce the ion transmission tortuosity, reduce the side reaction, and improve the rapid charging performance of the battery monomer 10.

[0271] The artificial graphite can have a small volume average particle size Dv50, which can shorten the solid-phase transmission path of lithium ions on one hand, and can improve the rapid charging performance; on the other hand, the material is not prone to agglomeration in the preparation process, and the stability of the material can be improved.

[0272] In some embodiments, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is 3:7 to 7:3. For example, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is 3:7, 4:6, 5:5, 6:4 or 7:3.

[0273] Optionally, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is 4:6 to 6:4.

[0274] By adjusting the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222, the gradient pore difference between the upper and lower layers can be further increased, the tortuosity of lithium ion transmission can be reduced, and the rapid charging capability of the battery monomer 10 can be improved.

[0275] In some embodiments, the thickness of the first negative electrode film layer 11221 is less than or equal to the thickness of the second negative electrode film layer 11222, which can further improve the rapid charging capability of the battery monomer 10.

[0276] In some embodiments, the first negative electrode active material is granular, and the second negative electrode active material is granular.

[0277] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material. Further optionally, the volume average particle size Dv50 of the first negative electrode active material is less than the volume average particle size Dv50 of the second negative electrode active material.

[0278] The particle size of the first negative electrode active material and the second negative electrode active material is different, which can improve the rapid charging performance of the battery monomer 10; in the rapid charging process, the overpotential of the first negative electrode film layer 11221 is usually high, and the bottleneck of rapid charging is mainly in the first negative electrode film layer 11221, and the particle size of the first negative electrode active material is relatively small in the present application, which can shorten the solid-phase transmission path of ions, improve the rapid charging performance, and improve the problem of ion precipitation on the surface layer of the negative electrode sheet 112. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer 11222, and the pores can absorb expansion during charging, reduce the expansion amount of the negative electrode film layer 1122, reduce the force exerted by the battery monomer 10 on the first bus member 30a, and reduce the risk of connection failure between the battery monomer 10 and the first bus member 30a.

[0279] In some embodiments, the first negative active material has a volume average particle size Dv50 of 7.8-14.3 μm, which can be 7.8-11.3 μm. Illustratively, the first negative active material has a volume average particle size Dv50 of 7.8 μm, 8.0 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.3 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, 13.8 μm, 14 μm, 14.1 μm, 14.3 μm, or a range defined by any two of the above values.

[0280] The first negative active material has a volume average particle size Dv50 of 7.8-14.3 μm, which can shorten the solid-phase transmission path of lithium ions, improve the rapid charging performance, and also can prevent the material from agglomeration during preparation, improve the stability of the material, and further facilitate the construction of a gradient pore difference between the first negative electrode film layer 11221 and the second negative electrode film layer 11222, reduce the tortuosity of lithium ion transmission, and improve the rapid charging performance of the battery cell 10.

[0281] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% of the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% of the volume distribution. The volume average particle size Dv50 and Dv10 of the negative active material can be detected by using a device and method known in the art, for example, by using a Mastersizer 2000E laser particle size analyzer according to the test standard GB / T 19077-2016.

[0282] In some embodiments, the second negative active material has a volume average particle size Dv50 of 9.5-18.5 μm, which can be 9.5-14.6 μm.

[0283] Illustratively, the second negative active material has a volume average particle size Dv50 of 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 14.6 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, or a range defined by any two of the above values.

[0284] The volume average particle size Dv50 of the second negative active material is 9.5 μm-18.5 μm, which can make the pores of the second negative film layer 11222 more abundant, and is beneficial to improve the rapid charging capability of the battery monomer 10 and reduce the expansion of the negative film layer 1122 during the charging process.

[0285] In some embodiments, the first negative active material includes graphite particles, and the volume average particle size Dv50 of the graphite particles in the first negative film layer 11221 is 7.8 μm-14.3 μm, which can be 7.8 μm-11.3 μm. Optionally, the first negative active material includes artificial graphite.

[0286] The second negative active material includes graphite particles, and the volume average particle size Dv50 of the graphite particles is 9.5 μm-18.5 μm, which can be 9.5 μm-14.6 μm. Optionally, the second negative active material includes natural graphite.

[0287] In some embodiments, the specific surface area of the negative active material is 0.5 m 2 / g-3 m 2 / g, which can be 0.6 m 2 / g-1.2 m 2 / g. Exemplarily, the specific surface area of the negative active material is 0.5 m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1.0 m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g, 2.0 m 2 / g, 2.1 m 2 / g, 2.2 m 2 / g, 2.3 m 2 / g, 2.4 m 2 / g, 2.5 m 2 / g, 2.6 m 2 / g, 2.7 m 2 / g, 2.8 m 2 / g, 2.9 m 2 / g, 3.0 m 2 / g or a range between any two of the above values.

[0288] The specific surface area of the material is in the meaning known in the art and can be detected by using devices and methods known in the art, for example, according to the test standard GB / T 19587-2017, taking the negative active material as a sample, and testing the specific surface area by using a Tri-Star 3020 specific surface area and pore size analyzer of the Micromeritics company in the United States.

[0289] In the embodiments of the present application, the specific surface area of the negative active material is limited to be greater than or equal to 0.5m 2 / g, which can improve the ability of the battery monomer 10 to be quickly charged; and the specific surface area of the negative active material is limited to be less than or equal to 3m 2 / g, which can reduce the side reaction of the battery monomer 10 during storage, slow down the expansion of the negative plate, and reduce the expansion pressure.

[0290] In some embodiments, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery monomer is 2.50g / cm 3 to 2.80g / cm 3 ; and can be 2.55g / cm 3 -2.70g / cm 3 . For example, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery monomer 10 is 2.50g / cm 3 , 2.52g / cm 3 , 2.55g / cm 3 , 2.56g / cm 3 , 2.57g / cm 3 , 2.58g / cm 3 , 2.60g / cm 3 , 2.62g / cm 3 , 2.65g / cm 3 , 2.68g / cm 3 , 2.30g / cm 3 , 2.32g / cm 3 , 2.75g / cm 3 , 2.78g / cm 3 , 2.80g / cm 3 , or a range between any two of the above values.

[0291] The compaction density of the positive electrode film layer 1112 in the above range is beneficial to improve the energy density of the battery monomer 10; and since the positive electrode active material in the positive electrode film layer 1112 is packed more closely, the contact resistance between particles is smaller, which can further reduce the resistance of the positive electrode sheet 111, thereby reducing the heat generation under fast charging.

[0292] In the embodiments of the present application, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery monomer 100 is the meaning known in the art, that is, the positive electrode sheet 111 is disassembled from the battery monomer 10 at 100% SOC, and the compaction density of the positive electrode film layer 1112 is measured. Exemplarily, the test method of the compaction density of the positive electrode film layer 1112 can be the same as the test method of the compaction density of the negative electrode film layer 1122.

[0293] In some embodiments, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 ; and can be 240 mg / 1540 mm 2 -330 mg / 1540 mm 2 . Exemplarily, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540.25 mm 2 , 210 mg / 1540.25 mm 2 , 220 mg / 1540.25 mm 2 , 230 mg / 1540.25 mm 2 , 240 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 270 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 310 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 330 mg / 1540.25 mm 2 , 340 mg / 1540.25 mm 2 , 350 mg / 1540.25 mm 2 , 360 mg / 1540.25 mm 2 , 370 mg / 1540.25 mm 2 , or a range composed of any two of the above values.

[0294] In the embodiments of the present application, the single-side coating weight of the positive electrode film layer 1112 is in the meaning known in the art, which can be detected by using the devices and methods known in the art, and the detection method is the same as the single-side coating weight test method of the negative electrode film layer 1122.

[0295] The single-side coating weight of the positive electrode film layer 1112 is set to 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 The heat generation per unit area of the positive electrode sheet 111 can be limited, and the energy density and the charge rate performance of the battery monomer 10 can be improved.

[0296] In some embodiments, the porosity of the positive electrode sheet 111 is 25%-32%. For example, the porosity of the positive electrode sheet 111 can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, or a range formed by any two of the above values.

[0297] In the embodiments of the present application, the porosity of the positive electrode sheet 111 is in the meaning known in the art, which can be detected by using the devices and methods known in the art, and the detection method is the same as the porosity test method of the negative electrode sheet 112.

[0298] The porosity of the positive electrode sheet 111 is greater than or equal to 25%, which can provide space for impurities generated by side reactions of the positive electrode sheet 111, reduce the swelling pressure of the battery monomer, reduce the deformation of the battery monomer 10, improve the cycle performance of the battery monomer 10, and reduce the risk of connection failure between the battery monomer and the busbar component. The porosity of the positive electrode sheet 111 is less than or equal to 32%, which can improve the energy density of the battery monomer 10 to a certain extent.

[0299] In some embodiments, the thickness of the positive electrode sheet 111 can be 0.13 mm-0.2 mm. For example, the thickness of the positive electrode sheet 111 can be 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, or a range formed by any two of the above values.

[0300] In the embodiments of the present application, the thickness of the positive electrode sheet 111 is in the meaning known in the art, which can be detected by using the devices and methods known in the art, for example, using a micrometer to measure the thickness of the positive electrode sheet 111.

[0301] Using the positive electrode sheet 111 with a smaller thickness can shorten the ion migration path, improve the ion migration rate, reduce the heat generation of the battery monomer 10, and improve the rapid charging performance of the battery monomer 10.

[0302] In some embodiments, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05 to 0.3. Illustratively, in the embodiments of the present application, the thickness of the positive electrode film layer 1112 is the thickness of the positive electrode film layer 1112 on one side of the positive electrode current collector 1111.

[0303] Illustratively, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, or a range defined by any two of the above values.

[0304] Limiting the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be greater than or equal to 0.05 can improve the flow capacity of the positive electrode current collector 1111, reduce the temperature rise of the positive electrode sheet 111, and improve the rapid charging performance of the battery monomer 10. Limiting the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be less than or equal to 0.3 can reduce the loss of capacity of the positive electrode sheet 111. The embodiments of the present application limit the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be 0.05 to 0.3, which can balance the rapid charging capacity and energy density of the battery monomer 10 to a certain extent.

[0305] The thickness of the positive electrode film layer and the thickness of the positive electrode current collector are well-known meanings in the art, which can be detected by using well-known devices and methods in the art. For example, the thickness of the positive electrode sheet is measured by using a micrometer, the thickness of the positive electrode current collector is measured by removing the film layer on the surface of the positive electrode current collector, and the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector when the positive electrode film layer is single-sided coated. When the positive electrode film layer is double-sided coated, the thickness of the positive electrode film layer is (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector) / 2.

[0306] In some embodiments, the thickness of the positive electrode current collector 1111 is 10 μm to 15 μm, which can be 12 μm to 15 μm. Illustratively, the thickness of the positive electrode current collector 1111 is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, or a range defined by any two of the above values. When the thickness of the positive electrode current collector 1111 is in the above range, the flow capacity of the positive electrode current collector 1111 is relatively excellent, and the battery monomer 10 can have a relatively high energy density.

[0307] In some embodiments, a part of the positive electrode current collector 1111 is not covered by the positive electrode film layer 1112; the part of the positive electrode current collector 1111 not covered by the positive electrode film layer 1112 can be used to form the positive electrode tab 11b.

[0308] In some embodiments, the positive electrode active material comprises a lithium-containing phosphate of olivine structure or a modified material thereof.

[0309] The lithium-containing phosphate of olivine structure or the modified material thereof can be a lithium-containing phosphate of olivine structure or a material obtained after coating modification. For example, the lithium-containing phosphate of olivine structure comprises phosphate particles and an ion-conducting layer, the ion-conducting layer being coated on the surface of the phosphate particles, the ion-conducting layer containing one or more elements of C, Fe, Ti, Zr, Hf, Ge and Sn.

[0310] In some embodiments, the mass fraction of the lithium-containing phosphate of olivine structure or the modified material thereof in the positive electrode active material can be greater than or equal to 80% and less than or equal to 100%, and the positive electrode active material of the present application can be considered as a lithium-containing phosphate of olivine structure or a modified material thereof system. When the mass fraction of the lithium-containing phosphate of olivine structure or the modified material thereof is less than 100%, the positive electrode active material can further comprise a commonly used positive electrode active material, for example, can comprise but is not limited to at least one of a lithium-containing transition metal oxide. Examples of the lithium-containing transition metal oxide can comprise but are not limited to at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and a modified compound of each thereof.

[0311] Optionally, the mass fraction of the lithium-containing phosphate of olivine structure or the modified material thereof in the positive electrode active material is 100%.

[0312] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1 μm≤Dv50≤2 μm, 0.4 μm≤Dv10≤0.7 μm.

[0313] For example, the Dv50 of the positive electrode active material can be 1 μm, 1.1 μm, 1.15 μm, 1.2 μm, 1.25 μm, 1.3 μm, 1.35 μm, 1.4 μm, 1.45 μm, 1.5 μm, 1.55 μm, 1.6 μm, 1.65 μm, 1.7 μm, 1.75 μm, 1.8 μm, 1.85 μm, 1.9 μm, 1.95 μm, 2 μm or a range formed by any two of the above values.

[0314] For example, the Dv10 of the positive electrode active material can be 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm or a range formed by any two of the above values.

[0315] The particle size of the positive electrode active material is relatively small, the lithium ion deintercalation lithium path in the positive electrode active material is short, and the heat production is less; and the particle size of the positive electrode active material is not too small, and the agglomeration can be reduced in the processing and preparation process, so that the performance of the positive electrode active material is stable.

[0316] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. The Dv50 and Dv10 of the particles can be detected by using devices and methods known in the art, for example, the positive electrode active material is taken as a sample, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer according to the test standard GB / T 19077-2016.

[0317] In some embodiments, the battery cell 10 includes an electrolyte contained in the shell 12. During the charging and discharging of the battery cell 10, active ions are embedded and de-embedded between the positive electrode sheet 111 and the negative electrode sheet 112, and the electrolyte plays a role in conducting active ions between the positive electrode sheet 111 and the negative electrode sheet 112.

[0318] In some embodiments, the electrolyte has an electrical conductivity of 13 mS / cm to 20 mS / cm at room temperature, which can be 15 mS / cm to 20 mS / cm. For example, the electrolyte has an electrical conductivity of 13 mS / cm, 13.5 mS / cm, 14 mS / cm, 14.5 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 16.5 mS / cm, 17 mS / cm, 17.5 mS / cm, 18 mS / cm, 18.5 mS / cm, 19 mS / cm, 19.5 mS / cm, 20 mS / cm or a range formed by any two of the above values at room temperature.

[0319] As an example, the room temperature can be 25℃.

[0320] When the electrical conductivity of the electrolyte is in the above range, the migration rate of ions in the electrolyte is high, thereby further reducing the internal resistance of the battery cell 10, reducing heat production, and improving the rapid charging performance of the battery cell 10.

[0321] The electrical conductivity of the electrolyte is the ionic conductivity, which can be detected by using devices and methods known in the art, for example, the industry standard HG-T 4067-2015 is referred to for testing.

[0322] In some embodiments, the density p of the electrolyte at room temperature satisfies: 1.05 g / mL≤p≤1.35 g / mL.

[0323] Exemplarily, the density p of the electrolyte is 1.05 g / mL, 1.10 g / mL, 1.15 g / mL, 1.2 g / mL, 1.25 g / mL, 1.3 g / mL, 1.35 g / mL, or a range formed by any two of the above values.

[0324] When the density p of the electrolyte is in the above range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery monomer 10, thereby reducing the heat generation and improving the rapid charging performance of the battery monomer 10.

[0325] In the embodiments of the present application, the density of the electrolyte is the meaning known in the art, which can be detected by using the devices and methods known in the art, for example, referring to GB / T 2013-2010 for testing.

[0326] In some embodiments, the electrolyte comprises an organic solvent, and the organic solvent comprises one or more of a carbonate-based solvent and a carboxylate-based solvent.

[0327] In some embodiments, the carboxylate-based solvent comprises a chain carboxylate-based solvent, and the mass content of the chain carboxylate-based solvent in the organic solvent is 5% to 75%. Exemplarily, the mass content of the chain carboxylate-based solvent is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or a range formed by any two of the above values. When the mass content of the chain carboxylate-based solvent is in the above range, the viscosity of the electrolyte system is relatively small, which is beneficial to the migration of lithium ions.

[0328] In some embodiments, the mass content of the chain carboxylate-based solvent in the organic solvent is 30% to 70%.

[0329] In some embodiments, the carboxylate comprises R1-COO-R2, and R1 and R2 each independently comprises an alkyl group with 1-5 carbon atoms or a halogenated alkyl group with 1-5 carbon atoms. The above chain carboxylate-based solvent has a relatively high conductivity, which is beneficial to improving the rapid charging capability of the battery monomer 10.

[0330] In some embodiments, the carbonate-based solvent comprises one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0331] Further optionally, the carbonate-based solvent comprises one or more of vinyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.

[0332] The above carbonate-based solvent and chain carboxylate-based solvent are used in combination, so that the conductivity of the electrolyte is improved, which is beneficial to the migration of lithium ions.

[0333] Further optionally, the mass content of the carbonate-based solvent in the organic solvent is 5% to 95%, optionally 25% to 60%, optionally 30% to 45%. Illustratively, the mass content of the carbonate-based solvent in the organic solvent is 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60%, or a range between any two of the foregoing values. The carbonate-based solvent in the above mass content can further improve the conductivity of the electrolyte, which is conducive to the migration of lithium ions.

[0334] Illustratively, the carbonate-based solvent includes one or more of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate, and the mass content of the carbonate-based solvent is 25% to 60%.

[0335] The organic solvent can improve the conductivity and reduce the viscosity of the electrolyte, thereby improving the rapid charging performance of the battery 2.

[0336] In some embodiments, the electrolyte includes a lithium salt. The lithium salt includes one or more of a fluorine-containing sulfimide salt and lithium hexafluorophosphate LiPF6. The above lithium salt is easy to dissociate, which is conducive to the rapid migration of lithium ions; and the electrolyte system is relatively stable and is not easy to decompose, which can improve the cycle performance of the battery monomer 10.

[0337] Optionally, the fluorine-containing sulfimide salt includes one or more of lithium bisfluorosulfimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI.

[0338] In some embodiments, the lithium salt includes lithium bisfluorosulfimide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L. Illustratively, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.4 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.7 mol / L. Illustratively, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L. Illustratively, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.2 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.8 mol / L.

[0339] Optionally, the ratio of the molar concentration of lithium bisfluorosulfonylimide to the molar concentration of lithium hexafluorophosphate LiPF6 is (2 to 5):10. Illustratively, the ratio of the molar concentration of lithium bisfluorosulfonylimide to the molar concentration of lithium hexafluorophosphate LiPF6 is 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10, 5:10, or a range defined by any two of the aforementioned values.

[0340] In some embodiments, the electrode assembly 11 has a dimension T in the thickness direction X, the single-layer negative electrode sheet 112 has a thickness T1, and the negative electrode sheet 112 has N layers stacked in the thickness direction X. T, T1, and N satisfy 0.3≤(N×T1) / T≤0.5.

[0341] The negative electrode sheet 112 includes at least a flat layer 112a perpendicular to the thickness direction X, and the electrode assembly 11 has N layers of the flat layer 112a.

[0342] Illustratively, the battery monomer 10 is disassembled at 0% state of charge, and the electrode assembly 11 is taken out; the micrometer is used to measure T and T1.

[0343] Illustratively, the electrode assembly 11 has a winding structure, and the negative electrode sheet 112 includes N flat layers 112a; alternatively, the electrode assembly 11 has a stacking structure, and the electrode assembly 11 includes N negative electrode sheets 112, each of which includes one flat layer 112a.

[0344] During the cycle of the battery monomer 10, the thickness of the negative electrode sheet 112 increases due to irreversible side reactions, causing the battery monomer 10 to expand; limiting (N×T1) / T to 0.3-0.5 can reduce the expansion of the battery monomer 10 and reduce the risk of failure of the connection between the battery monomer 10 and the busbar component 30.

[0345] In some embodiments, the limiting beam 21 is an integrally formed structure, which can reduce the connection weakness of the limiting beam 21 and help improve the structural strength and rigidity of the limiting beam 21. Alternatively, the limiting beam 21 can also be spliced from multiple components, for example, the limiting beam 21 is spliced from multiple sheet metal parts.

[0346] In some embodiments, the limiting beam 21 is a profiled beam.

[0347] The limiting beam 21 can be a hollow beam structure integrally formed by stamping / extruding or metal casting of a plate body or a rod. The limiting beam 21 can have a wall thickness of 1-8 mm, and a wall thickness of 3-5 mm is commonly used. In this wall thickness, the limiting beam 21 has a good cost performance, has a relatively light weight, and has a good structural strength, which can effectively suppress the expansion deformation of the battery monomer 10 during the cycle.

[0348] The limiting beam 21 can be made of steel, iron, aluminum, aluminum alloy, or the like.

[0349] In some embodiments, the box 20 includes a frame 22 and a support beam 23. The frame 22 defines a containing space in which the limiting beam 21 and the plurality of battery cells 10 are arranged. The support beam 23 is arranged on the side of the limiting beam 21 away from the plurality of battery cells 10 and connects the frame 22 and the limiting beam 21.

[0350] Optionally, the frame 22 can be a rectangular frame.

[0351] The support beam 23 can be one or multiple.

[0352] For two adjacent limiting beams 21, one limiting beam 21 can be connected to the support beam 23, or both limiting beams 21 can be connected to the support beam 23.

[0353] During the cycle of the battery 2, the limiting beam 21 is used to resist the expansion force of the battery cells 10 during the cycle. The frame 22 can support the limiting beam 21 through the support beam 23, thereby providing effective support for the limiting beam 21, reducing the deformation of the limiting beam 21, and further providing constraint to the battery cells 10, reducing the expansion of the battery cells 10, and improving the cycle life of the battery cells 10.

[0354] By setting the support force connecting the frame 22 and the limiting beam 21, the overall structural strength and rigidity of the box 20 can be improved, and the risk of cracking of the box 20 can be reduced.

[0355] In some embodiments, the frame 22 includes a plurality of edge beams arranged in sequence and connected to form a ring-shaped frame 22.

[0356] In some embodiments, the support beam 23 extends along the thickness direction X. Optionally, the cross section of the support beam 23 perpendicular to the thickness direction X can be rectangular, trapezoidal, elliptical, circular, L-shaped, or other shapes.

[0357] In some embodiments, the support beam 23 is a plate body or a hollow beam structure. The support beam 23 can be made of steel, aluminum, or aluminum alloy.

[0358] In some embodiments, the support beam 23 and the frame 22 can be fixedly connected by welding, bolting, or clamping.

[0359] In some embodiments, the limiting beam 21 extends in a direction perpendicular to the thickness direction X. The box 20 comprises a plurality of support beams 23 arranged at intervals along the width direction Y of the limiting beam 21. The plurality of support beams 23 can increase the constraint force on the limiting beam 21, improve the uniformity of the stress on different regions of the limiting beam 21, reduce the deformation of the limiting beam 21 during the cycling of the battery cell 10, and improve the cycling performance of the battery 2.

[0360] In some embodiments, the box 20 further comprises a bearing plate 24, and the plurality of battery cells 10 and the limiting beam 21 are located on the same side of the bearing plate 24 and are fixed to the bearing plate 24. For example, the bearing plate 24 and the plurality of battery cells 10 are arranged along the height direction Z of the battery cell 10.

[0361] In some embodiments, the box 20 further comprises a cover plate (not shown) arranged opposite to the bearing plate 24 along the height direction Z and fixed to the frame 22. The battery cell and the limiting beam are located between the cover plate and the bearing plate.

[0362] In some examples, the bearing plate 24 is located on the upper side of the battery cell, and the battery cell is inverted; alternatively, in other examples, the bearing plate 24 is located on the lower side of the battery cell, and the battery cell is upright.

[0363] FIG. 13 is a top view of a battery according to some embodiments of the present application; FIG. 14 is an enlarged view of the box in FIG. 13; and FIG. 15 is a structural view of a second current collecting component in FIG. 14.

[0364] Referring to FIG. 6 and FIGS. 13-15, in some embodiments, the battery 2 further comprises at least one second current collecting component 30b, the second current collecting component 30b is a single-layer structure and is electrically connected to at least two battery cells 10, the thickness of the second current collecting component 30b is greater than the thickness of the first current collecting layer 31, and the thickness of the second current collecting component 30b is greater than the thickness of the second current collecting layer 32.

[0365] For example, among the plurality of current collecting components 30, a part of the current collecting components 30 are the first current collecting components 30a, and the other part of the current collecting components 30 are the second current collecting components 30b.

[0366] In the battery 2, the expansion amount of the battery cells 10 at different positions can be different. For the battery cell 10 with a smaller expansion amount, the second current collecting component 30b with a single-layer structure can be used; compared with the first current collecting component 30a, the second current collecting component 30b is simple in structure, easy to manufacture, and can save costs. The thickness of the second current collecting component 30b is greater than the thickness of the first current collecting layer 31 and the thickness of the second current collecting layer 32, and the current carrying capacity of the second current collecting component 30b can meet the requirements.

[0367] In some embodiments, the sum of the thickness of the first busbar layer 31 and the thickness of the second busbar layer 32 is equal to the thickness of the second busbar component 30b. The embodiments of the present application can reduce the difference in overcurrent capacity between the first busbar component 30a and the second busbar component 30b, and improve current consistency.

[0368] In some embodiments, the second busbar component 30b connects at least two battery cells 10 arranged in the thickness direction X.

[0369] In some embodiments, among the plurality of battery cells 10, the battery cell 10 located at the outermost side in the thickness direction X is connected to the first busbar component 30a.

[0370] During charging, the expansion of the plurality of battery cells 10 can be superimposed in the thickness direction X, which causes the displacement of the battery cell 10 located at the outermost side in the thickness direction X to be larger. The use of the first busbar component 30a with a double-layer structure to connect the battery cell 10 at the outermost side can reduce the risk of failure of the connection between the first busbar component 30a and the battery cell 10.

[0371] For example, the battery cell 10 located at the outermost side in the thickness direction X is connected to the first busbar layer 31.

[0372] In some embodiments, the battery cell 10 adjacent to the limiting beam 21 can be connected to the first busbar component 30a.

[0373] In some embodiments, the plurality of busbar components 30 further comprises a third busbar component 30c, which can connect two battery cells 10 adjacent in the width direction Y.

[0374] In some embodiments, the charging time of the battery cell 10 from 10% SOC to 80% SOC in an external environment of 25°C to 35°C is 5 minutes to 10.5 minutes. Alternatively, the charging time of the battery cell 10 from 10% SOC to 80% SOC in an external environment of 25°C to 35°C can be 5 min to 10.5 min. For example, the charging time of the battery cell 10 from 10% state of charge to 80% state of charge is 10.5 min, 10 min, 9.5 min, 9 min, 8.5 min, 8 min, 7.5 min, 7 min, 6.5 min, 6 min, 5.5 min, 5 min, or a range formed by any two of the above values.

[0375] The battery cell 10 of the embodiments of the present application has fast charging capability, which can save charging time.

[0376] In some embodiments, the charging steps of the battery 2 or any battery cell 10 constituting the battery 2 from 10% to 80% can be performed as follows:

[0377] Charge from 10% SOC to 15% SOC at a constant current of 5.0C;

[0378] Charge from 15% SOC to 20% SOC at a constant current of 5.0C;

[0379] Charge from 20% SOC to 25% SOC at a constant current of 5.0C;

[0380] Charge from 25% SOC to 30% SOC at a constant current of 5.0C;

[0381] Charge from 30% SOC to 35% SOC at a constant current of 5.0C;

[0382] Charge from 35% SOC to 40% SOC at a constant current of 5.0C;

[0383] Charge from 40% SOC to 45% SOC at a constant current of 4.6C;

[0384] Charge from 45% SOC to 50% SOC at a constant current of 4.3C;

[0385] Charge from 50% SOC to 55% SOC at a constant current of 4.0C;

[0386] Charge from 55% SOC to 60% SOC at a constant current of 3.7C;

[0387] Charge from 60% SOC to 65% SOC at a constant current of 3.4C;

[0388] Charge from 65% SOC to 70% SOC at a constant current of 3.1C;

[0389] Charge from 70% SOC to 75% SOC at a constant current of 2.9C;

[0390] Charge from 75% SOC to 80% SOC at a constant current of 2.7C.

[0391] As an example, the above charging strategy is carried out in an environment of 30°C.

[0392] In some embodiments, the charging step of the battery cell 10 from 0% SOC to 10% SOC can be performed as follows: charging from 0% SOC to 10% SOC at a constant current of 5.0C.

[0393] In some embodiments, the charging step of the battery cell 10 from 80% SOC to 98% SOC can be performed as follows:

[0394] Charge from 80% SOC to 85% SOC at a constant current of 1.8C;

[0395] Charge from 85% SOC to 90% SOC at a constant current of 1.3C;

[0396] charging from 90% SOC to 95% SOC at 0.7C constant current;

[0397] charging from 95% SOC to 98% SOC at 0.33C constant current.

[0398] In some embodiments, the battery cell 10 charging step from 98% SOC to 100% SOC can be performed as follows: charging from 98% SOC to 100% SOC at 0.01C, 0.05C, 0.1C, or 0.3C constant current. Alternatively, the battery cell 10 charging step from 98% SOC to 100% SOC can be performed as follows: charging from 98% SOC to 100% SOC at 0.01C, 0.05C, or 0.1C constant current.

[0399] In some embodiments, the battery cell 10 charging step from 10% SOC to 80% SOC can be performed at a constant current of 2C-6C, alternatively 2.7C-5C. The constant current can vary during the charging step depending on the SOC of the battery cell 10.

[0400] In some embodiments, the battery cell 10 is a lithium ion battery cell. After cycling the battery cell 10 for 20 cycles according to the charging and discharging strategies, the anode sheet of the battery cell 10 is disassembled and the lithium precipitation area of the anode sheet is observed and measured. The ratio of the lithium precipitation area to the total area of the anode sheet is less than 2%.

[0401] As an example, the discharging strategy can be discharging to 2.0V at 0.33C constant current.

[0402] As an example, the charging strategy can be:

[0403] charging from 0% SOC to 5% SOC at 5.0C constant current;

[0404] charging from 5% SOC to 10% SOC at 5.0C constant current;

[0405] charging from 10% SOC to 15% SOC at 5.0C constant current;

[0406] charging from 15% SOC to 20% SOC at 5.0C constant current;

[0407] charging from 20% SOC to 25% SOC at 5.0C constant current;

[0408] charging from 25% SOC to 30% SOC at 5.0C constant current;

[0409] charging from 30% SOC to 35% SOC at 5.0C constant current;

[0410] charging from 35% SOC to 40% SOC at 5.0 C;

[0411] charging from 40% SOC to 45% SOC at 4.6 C;

[0412] charging from 45% SOC to 50% SOC at 4.3 C;

[0413] charging from 50% SOC to 55% SOC at 4.0 C;

[0414] charging from 55% SOC to 60% SOC at 3.7 C;

[0415] charging from 60% SOC to 65% SOC at 3.4 C;

[0416] charging from 65% SOC to 70% SOC at 3.1 C;

[0417] charging from 70% SOC to 75% SOC at 2.9 C;

[0418] charging from 75% SOC to 80% SOC at 2.7 C;

[0419] charging from 80% SOC to 85% SOC at 1.8 C;

[0420] charging from 85% SOC to 90% SOC at 1.3 C;

[0421] charging from 90% SOC to 95% SOC at 0.7 C;

[0422] charging from 95% SOC to 98% SOC at 0.33 C;

[0423] charging from 98% SOC to 100% SOC at 0.1 C.

[0424] The battery cell 10 of the embodiments of the present application can be charged from 10% SOC to 80% SOC within 10.5 minutes without lithium precipitation or with slight lithium precipitation, and has good rapid charging capability. For example, the ratio of the area of the lithium precipitation region to the total area of the negative electrode sheet is less than 0.05% for no lithium precipitation, and the ratio of the area of the lithium precipitation region to the total area of the negative electrode sheet is less than 2% and greater than or equal to 0.05% for slight lithium precipitation.

[0425] According to some embodiments of the present application, the present application also provides an electric device, comprising the battery 2 of any of the above embodiments, and the battery 2 is used to provide electric energy for the electric device. The electric device can be the device or system of any of the above applications of the battery 2.

[0426] Referring to FIGS. 2 to 12, the embodiment of the present application provides a battery 2 including a plurality of battery cells 10, a case 20, and a plurality of busbar members 30. The plurality of battery cells 10 are housed in the case 20.

[0427] The battery cell 10 includes a housing 12 and an electrode assembly 11 housed in the housing 12. The battery cell has an expansion pressure of 0.5 MPa to 2.4 MPa in a thickness direction X.

[0428] The electrode assembly 11 includes a positive electrode tab 111, a negative electrode tab 112, and a separator 113 that separates the positive electrode tab 111 and the negative electrode tab 112. Optionally, the positive electrode tab 111, the negative electrode tab 112, and the separator 113 are wound.

[0429] The negative electrode tab 112 includes a negative electrode current collector 1121 and a negative electrode film layer 1122 provided on at least one side of the negative electrode current collector 1121, the negative electrode film layer 1122 including a negative electrode active material. The negative electrode tab 112 has a porosity of 27% to 40%. The negative electrode film layer 1122 has a packing density of 1.15 g / cm 3 to 1.36 g / cm 3 .

[0430] The negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222 provided between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material provided in the first negative electrode film layer 11221 and a second negative electrode active material provided in the second negative electrode film layer 11222, the first negative electrode active material including artificial graphite, and the second negative electrode active material including one or more of artificial graphite, natural graphite, and a silicon-based material. The first negative electrode active material has a volume average particle diameter Dv50 that is less than or equal to a volume average particle diameter Dv50 of the second negative electrode active material.

[0431] The positive electrode tab 111 includes a positive electrode current collector 1111 and a positive electrode film layer 1112 provided on at least one side of the positive electrode current collector 1111. The positive electrode film layer 1112 has a packing density of 2.50 g / cm 3 to 2.80 g / cm 3 at 100% SOC of the battery cell. The positive electrode tab 111 has a porosity of 25% to 32%. A ratio of a thickness of the positive electrode current collector 1111 to a thickness of the positive electrode film layer 1112 is 0.05 to 0.3. The positive electrode active material includes a lithium-containing phosphate having an olivine structure or a modified material thereof. The positive electrode active material has a volume average particle diameter satisfying 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm.

[0432] The case 20 includes two limiting beams 21 which are arranged at intervals in the thickness direction X of the battery cell 10. The plurality of battery cells 10 are arranged in a plurality of battery cell rows 100 which are arranged in the width direction Y of the limiting beam 21, and each battery cell row 100 includes at least two battery cells 10 arranged in the thickness direction X of the battery cell 10. The plurality of battery cells 10 are arranged between the two limiting beams 21.

[0433] The case 20 includes a frame 22 which defines a housing space in which the limiting beams 21 and the plurality of battery cells 10 are arranged, and a support beam 23 which is arranged on the side of the limiting beam 21 facing away from the plurality of battery cells 10 and which connects the frame 22 and the limiting beam 21. The restraint member 40 connects adjacent limiting beams 21 and is bonded to the battery cell 10.

[0434] The plurality of busbar members 30 electrically connect the plurality of battery cells 10. The plurality of busbar members 30 includes at least one first busbar member 30a which includes a first busbar layer 31 and a second busbar layer 32 which are stacked and connected, and the first busbar layer 31 connects at least two battery cells 10 arranged in the thickness direction X.

[0435] Embodiments

[0436] The following examples are provided to more fully demonstrate the application disclosed herein and are not intended to limit the scope of the application. Unless otherwise indicated, all parts, percentages, and ratios reported herein are based upon the weight of the material being measured and all reagents used in the examples are commercially available or are prepared according to conventional methods and used without further purification, unless otherwise indicated. The equipment used in the examples is commercially available.

[0437] Example 1

[0438] 1. Preparation of the positive electrode tab

[0439] The positive electrode tab includes a positive electrode current collector and positive electrode film layers arranged on both sides of the positive electrode current collector, and the positive electrode current collector is an aluminum foil with a thickness of 15 μm.

[0440] The positive electrode film layer includes a film layer formed by uniformly coating a positive electrode slurry (solvent: N-methyl pyrrolidone NMP) on the surface of the positive electrode conductive layer, and drying and cold-pressing, and the positive electrode film layer includes a positive electrode active material, a binder polyvinylidene fluoride (PVDF), and a conductive agent acetylene black in a weight ratio of 97:2:1.

[0441] The positive electrode active material includes lithium iron phosphate and an ion-conductive layer, the ion-conductive layer is coated on the surface of the lithium iron phosphate, and the ion-conductive layer includes lithium titanium iron phosphate Li2FeTi(PO4)3 and amorphous carbon. The Dv50 of the positive electrode active material is 1.6 μm, and the Dv10 is 0.64 μm.

[0442] The single-side coating weight of the positive electrode film layer is 0.21 g / 1540.25 mm 2 , and the compaction density of the positive electrode film layer after cold pressing is 2.6 g / cm 3 .

[0443] 2. Preparation of the negative electrode sheet

[0444] The negative electrode sheet includes a negative electrode current collector and negative electrode film layers arranged on both sides of the negative electrode current collector, and the negative electrode current collector is a copper foil with a thickness of 6 μm.

[0445] The negative electrode film layer includes a film layer formed by uniformly coating a negative electrode slurry (with deionized water as a solvent) on the surface of a negative electrode conductive layer, and then drying and cold pressing.

[0446] The single-side coating weight of the negative electrode film layer is 0.096 g / 1540.25 mm 2 , and the compaction density of the negative electrode film layer after cold pressing is 1.6 g / cm 3 .

[0447] The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, and the second negative electrode film layer is located between the first negative electrode film layer and the negative electrode current collector.

[0448] The second negative electrode film layer includes graphite particles, a conductive agent acetylene black, a second lithium-containing binder (a lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, in which the molar ratio of lithium acrylate monomers, acrylonitrile monomers, acrylamide monomers, and hydroxyethyl acrylate monomers is 35%:30%:15%:20%), a negative electrode binder styrene butadiene rubber, and a thickening agent sodium carboxymethyl cellulose, the mass ratio of which is 96.5:0.5:0.5:1.5:1, the mass content of lithium in the second lithium-containing binder is 4.8%, the Dv50 of the graphite particles is 11.3 μm, the graphite particles include artificial graphite and a carbon coating layer, the carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0449] The first negative electrode film layer comprises graphite particles, conductive agent acetylene black, first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene butadiene rubber, thickening agent sodium carboxymethyl cellulose, the mass content of lithium element in the first lithium-containing binder is 4.8%, the Dv50 of the graphite particles is 11.3 microns, and the graphite particles comprise artificial graphite and a carbon coating layer, the carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0450] 3. Isolation film

[0451] The isolation film comprises a base film, and the base film is a 7-micron polyethylene film layer with a porosity of 42%.

[0452] 4. Preparation of electrolyte

[0453] The electrolyte comprises an organic solvent, a lithium salt and an additive.

[0454] The organic solvent comprises 60% chain carboxylate solvents (ethyl acetate) and 40% carbonate solvents (30% ethylene carbonate EC, and the rest is dimethyl carbonate), and the mass content of each component in the organic solvent is calculated based on the mass of the organic solvent.

[0455] The mass content of the additive is 6.5% based on the mass of the electrolyte, and the additive comprises vinylene carbonate VC, fluoroethylene carbonate FEC, ethylene sulfite ES and lithium difluoro(oxalato)borate LiDFOB in a mass ratio of 5:0.5:0.5:0.5.

[0456] The lithium salt comprises 1 mol / L lithium hexafluorophosphate LiPF6.

[0457] The conductivity of the electrolyte at room temperature is 16.4 mS / cm.

[0458] 5. Preparation of battery monomer

[0459] The above positive electrode sheet, isolation film and negative electrode sheet are stacked in order, the isolation film is between the positive electrode sheet and the negative electrode sheet to play a separation role, an electrode assembly is obtained, the electrode assembly is placed in a shell, electrolyte is injected after drying, and the battery monomer is obtained through processes such as vacuum packaging, standing, formation and shaping.

[0460] 6. Preparation of battery

[0461] The prepared plurality of battery monomers are installed in a box, then a plurality of bus components are welded with electrode terminals of the plurality of battery monomers, and a high-low voltage wire harness is installed, to obtain a battery.

[0462] The busbar component can be the first busbar component shown in FIG. 6, which has a double-layer structure. The thickness Th of the single-layer structure of the first busbar component is 1.5 mm, i.e., the thickness of the first busbar layer is 1.5 mm and the thickness of the second busbar layer is 1.5 mm.

[0463] Example 2

[0464] The battery monomer and the battery were prepared by using a method similar to that of Example 1, except that the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compactness of the negative electrode film layer after cold pressing were adjusted.

[0465] Example 3

[0466] The battery monomer and the battery were prepared by using a method similar to that of Example 1, except that the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compactness of the negative electrode film layer after cold pressing were adjusted.

[0467] Example 4

[0468] The battery monomer and the battery were prepared by using a method similar to that of Example 1, except that the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, the compactness of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first busbar component were adjusted.

[0469] Example 5

[0470] The battery monomer and the battery were prepared by using a method similar to that of Example 1, except that the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, the compactness of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first busbar component were adjusted.

[0471] Example 6

[0472] The battery monomer and the battery were prepared by using a method similar to that of Example 1, except that the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, the compactness of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first busbar component were adjusted.

[0473] Example 7

[0474] A battery cell and a battery were produced in a similar manner to Example 1, except that the single-side coating weight of the positive electrode film layer, the compaction density after cold-pressing of the positive electrode film layer, the single-side coating weight of the negative electrode film layer, the compaction density after cold-pressing of the negative electrode film layer, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0475] Comparative Example 1

[0476] A battery cell and a battery were produced in a similar manner to Example 1, except that the single-side coating weight of the positive electrode film layer, the single-side coating weight of the negative electrode film layer, and the compaction density after cold-pressing of the negative electrode film layer were adjusted.

[0477] Comparative Example 2

[0478] A battery cell and a battery were produced in a similar manner to Example 1, except that the single-side coating weight of the positive electrode film layer, the compaction density after cold-pressing of the positive electrode film layer, the single-side coating weight of the negative electrode film layer, the compaction density after cold-pressing of the negative electrode film layer, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0479] Comparative Example 3

[0480] A battery cell and a battery were produced in a similar manner to Example 1, except that the single-side coating weight of the positive electrode film layer, the compaction density after cold-pressing of the positive electrode film layer, the single-side coating weight of the negative electrode film layer, the compaction density after cold-pressing of the negative electrode film layer, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0481] Comparative Example 4

[0482] A battery cell and a battery were produced in a similar manner to Example 1, except that the single-side coating weight of the positive electrode film layer, the compaction density after cold-pressing of the positive electrode film layer, the single-side coating weight of the negative electrode film layer, the compaction density after cold-pressing of the negative electrode film layer, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0483] Performance Test

[0484] 1. Test the expansion pressure of the battery cell:

[0485] The battery cell produced above was discharged to 2.0 V at a constant current discharge rate of 1C in an environment at a temperature of 45°C.

[0486] The battery cell was clamped between two clamping plates, wherein the two clamping plates were respectively located on both sides of the battery cell in the thickness direction and covered a large area.

[0487] At an ambient temperature of 45°C, the battery cells were charged to 3.8V at a constant current charging rate of 0.8C, and the pressure exerted by the battery cells on the clamping plate was detected and recorded.

[0488] The battery cells were cyclically charged and discharged according to the above charging strategy until the battery cells degraded to 70% SOH (the discharge capacity of the battery cells degraded to 70% of the nominal capacity of the battery cells), and the maximum pressure exerted by the battery cells on the clamping plate was recorded.

[0489] The expansion pressure Q of a single battery cell in the thickness direction is calculated as: maximum pressure / large surface area.

[0490] 2. Volumetric energy density test:

[0491] The discharge energy in the first week was tested according to the following steps: At 25°C, the prepared battery cell was charged to 3.8V with a constant current of 0.33C, and then discharged to 2.0V with a constant current of 0.33C. The discharge energy A0 at this time was recorded, in Wh.

[0492] Volume of a single battery cell: Use calipers to measure the length, width, and height of the single battery cell (generally calculated based on the outer casing dimensions, excluding the height of the electrode terminals and the insulating film outside the casing), and calculate the volume of the single battery cell V0, in liters (L).

[0493] The volumetric energy density of a single battery cell is VED = A0 / V0, in Wh / L.

[0494] 3. Cyclic performance test one:

[0495] The battery prepared above was discharged at an ambient temperature of 45°C, and the battery cells were discharged to 2.0V at a constant current discharge rate of 1C.

[0496] The battery prepared above was charged at an ambient temperature of 45°C, and the battery cells were charged to 3.8V at a constant current charging rate of 0.8C.

[0497] The battery is cycled through charging and discharging according to the above charging strategy until the battery degrades to 70% SOH (battery discharge capacity / battery nominal capacity = 70%).

[0498] During the cycle, the highest temperature of the end cap of the battery cell casing is detected, and it is observed whether the weld between the first busbar and the electrode terminal is cracked.

[0499] 4. Cyclic performance test two:

[0500] The battery prepared above was discharged at an ambient temperature of 30°C, and the battery cells were discharged to 2.0V at 0.33C.

[0501] Charged at ambient temperature of 30°C using the following charge strategy:

[0502] Charge from 0% SOC to 5% SOC at 5.0 C constant current;

[0503] Charge from 5% SOC to 10% SOC at 5.0 C constant current;

[0504] Charge from 10% SOC to 15% SOC at 5.0 C constant current;

[0505] Charge from 15% SOC to 20% SOC at 5.0 C constant current;

[0506] Charge from 20% SOC to 25% SOC at 5.0 C constant current;

[0507] Charge from 25% SOC to 30% SOC at 5.0 C constant current;

[0508] Charge from 30% SOC to 35% SOC at 5.0 C constant current;

[0509] Charge from 35% SOC to 40% SOC at 5.0 C constant current;

[0510] Charge from 40% SOC to 45% SOC at 4.6 C constant current;

[0511] Charge from 45% SOC to 50% SOC at 4.3 C constant current;

[0512] Charge from 50% SOC to 55% SOC at 4.0 C constant current;

[0513] Charge from 55% SOC to 60% SOC at 3.7 C constant current;

[0514] Charge from 60% SOC to 65% SOC at 3.4 C constant current;

[0515] Charge from 65% SOC to 70% SOC at 3.1 C constant current;

[0516] Charge from 70% SOC to 75% SOC at 2.9 C constant current;

[0517] Charge from 75% SOC to 80% SOC at 2.7 C constant current;

[0518] Charge from 80% SOC to 85% SOC at 1.8 C constant current;

[0519] Charge from 85% SOC to 90% SOC at 1.3 C constant current;

[0520] Charge from 90% SOC to 95% SOC at 0.7 C constant current;

[0521] 0.33C constant current from 95% SOC to 98% SOC;

[0522] 0.1C constant current from 98% SOC to 100% SOC.

[0523] The battery is cycled according to the above charging strategy and the charging strategy until the battery decays to 70% SOH.

[0524] During the cycling process, the maximum temperature of the end cap of the battery cell is detected, and whether the welding between the first current collecting component and the electrode terminal is cracked is observed.

[0525] It is explained that the cycle performance test one and the cycle performance test two are respectively performed on two batteries prepared by the same preparation method.

[0526] The test results of examples 1-7 and comparative examples 1-4 are shown in table 1.

[0527] Referring to comparative example 1 in table 1, the single-side coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing are low. Although the battery cell has a small swelling pressure, and the welding between the electrode terminal and the first current collecting component is not easy to crack during the cycling process, the volumetric energy density of the battery cell is low.

[0528] Referring to examples 1-7 and comparative examples 1-4, the single-side coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing can be increased in the examples of the present application, so that the volumetric energy density of the battery cell is greater than or equal to 390 Wh / L. Although the swelling pressure of the battery cell is not less than 0.5 MPa, in combination with the first current collecting component having a double-layer structure, the risk of welding cracking caused by the increase of the swelling pressure can be reduced, and the reliability of the battery can be improved. The first current collecting component has a double-layer structure, and has strong current carrying capacity, thereby reducing the heat generation of the first current collecting component during the cycling process, and further reducing the heat conducted to the end cap and the electrode assembly, reducing the temperature rise of the battery cell, and improving the cycle performance of the battery.

[0529] Referring to examples 1-7 and comparative examples 2-3, by adjusting the single-side coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing, the swelling pressure of the battery cell can be limited to not more than 2.4 MPa, and the volumetric energy density of the battery cell can reach 415 Wh / L.

[0530] ​​By adjusting the thickness of the single-layer structure of the first bus member, the overcurrent capacity and the deformability of the first bus member can be balanced. When the expansion pressure of the battery cell is 0.5 MPa-2.4 MPa, limiting the thickness of the single-layer structure of the first bus member to not more than 2.5 mm can reduce the risk of the weld between the electrode terminal and the first bus member being cracked, reduce the heat generated by the first bus member during cycling, and thus reduce the heat conducted to the end cover and the electrode assembly, reduce the temperature rise of the battery cell, and improve the cycle performance of the battery.

[0531] With reference to Examples 1-7 and Comparative Example 4, by adjusting the thickness of the single-layer structure of the first bus member, the overcurrent capacity and the deformability of the first bus member can be balanced. The present application limits the thickness of the single-layer structure of the first bus member to not less than 1 mm, which can improve the overcurrent capacity when the expansion pressure of the battery cell is 0.5 MPa-2.4 MPa, reduce the heat generated by the first bus member during cycling, and thus reduce the heat conducted to the end cover and the electrode assembly, reduce the temperature rise of the battery cell, and improve the cycle performance of the battery.

[0532] With reference to Examples 1-7 of Table 1, the present application can reduce the heat generation of the first bus member during fast charging of the battery, and reduce the expansion of the battery cell to reduce the risk of battery failure. The battery cell of the present application has the ability to fast charge, and the charging time of the battery cell from 10% SOC to 80% SOC can be 5 minutes to 10.5 minutes.

[0533] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0534] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement to part of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, comprising: Multiple battery cells are arranged along their thickness direction. Each battery cell includes a casing and an electrode assembly housed within the casing. The expansion pressure of each battery cell in the thickness direction is 0.5 MPa to 2.4 MPa. The first busbar component electrically connects at least two of the battery cells arranged along the thickness direction. The first busbar component has a multi-layer structure. The electrode assembly includes a positive electrode, a negative electrode, and a separator 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 phosphate with an olivine structure. The negative electrode 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 active material, which includes a carbon-based material.

2. The battery according to claim 1, wherein, The first busbar component includes a first busbar layer and a second busbar layer that are stacked and connected, wherein the first busbar layer connects at least two of the battery cells arranged along the thickness direction.

3. The battery according to claim 2, wherein, The battery cell includes electrode terminals disposed on the housing, and the electrode terminals are electrically connected to the electrode assembly; The portion of the first bus layer that does not overlap with the second bus layer is connected to the electrode terminal.

4. The battery according to claim 3, wherein, The first bus layer is soldered to the electrode terminal, and the soldering area between the first bus layer and the electrode terminal is greater than or equal to 60 mm². 2 .

5. The battery according to any one of claims 2-4, wherein, The first busbar component includes at least one bend, which connects the first busbar layer and the second busbar layer.

6. The battery according to claim 5, wherein, The first busbar layer includes a first busbar section, a second busbar section, and a first buffer section. The first busbar section and the second busbar section are disposed along the thickness direction and connected to different battery cells. The first buffer section connects the first busbar section and the second busbar section. At least one of the first busbar and the second busbar is connected to the bend.

7. The battery according to claim 6, wherein, The bent portion is positioned to avoid the first buffer portion.

8. The battery according to claim 6 or 7, wherein, The second bus layer includes a first stacked portion, a second stacked portion, and a second buffer portion. The first stacked portion is stacked with the first bus layer and connected to it through at least one of the bending portions. The second stacked portion is stacked with the second bus layer and connected to it through at least one of the bending portions. The second buffer section connects the first stacked section and the second stacked section; In the stacking direction of the first busbar layer and the second busbar layer, the second buffer portion overlaps at least partially with the first buffer portion.

9. The battery according to claim 8, wherein, The second buffer part and the first buffer part are fitted together.

10. The battery according to any one of claims 2-9, wherein, The battery further includes at least one second busbar component, which is a single-layer structure and electrically connected to at least two battery cells. The thickness of the second busbar component is greater than the thickness of the first busbar layer, and the thickness of the second busbar component is greater than the thickness of the second busbar layer.

11. The battery according to claim 10, wherein, The sum of the thickness of the first busbar layer and the thickness of the second busbar layer is equal to the thickness of the second busbar component.

12. The battery according to any one of claims 2-11, wherein, The thickness of the first busbar layer is 1mm-2.5mm; and / or The thickness of the second busbar is 1mm-2.5mm.

13. The battery according to any one of claims 2-12, wherein, The volumetric energy density of the battery cell is 390Wh / L-450Wh / L, and the thickness of the first busbar is less than or equal to 2.5mm; or, The volumetric energy density of the battery cell is 450Wh / L-480Wh / L, and the thickness of the first busbar is less than or equal to 2.2mm.

14. The battery according to any one of claims 2-13, wherein, The negative electrode active material also includes silicon-based materials; The silicon-based material contains 1%-6% silicon by mass in the negative electrode active material; the thickness of the first busbar layer is 1.2mm-2.2mm, and the thickness of the second busbar layer is 1.2mm-2.2mm.

15. The battery according to any one of claims 2-14, wherein, The first busbar layer includes a first busbar section, a second busbar section, and a first buffer section connecting the first busbar section and the second busbar section. The first busbar section and the second busbar section are disposed along the thickness direction and connected to different battery cells. In the stacking direction of the first busbar layer and the second busbar layer, the first buffer portion protrudes from the first busbar portion and the second busbar portion; The first busbar layer has a recess at a position corresponding to the first buffer section.

16. The battery according to claim 15, wherein, The volumetric energy density of the battery cell is 390Wh / L-450Wh / L, and the depth of the recess is 1.2mm-2.5mm; or, The volumetric energy density of the battery cell is 450Wh / L-480Wh / L, and the depth of the recess is 1mm-2.2mm.

17. The battery according to any one of claims 1-16, wherein, Among the plurality of battery cells, the outermost battery cell along the thickness direction is connected to the first busbar component.

18. The battery according to any one of claims 1-17, wherein, The electrode assembly includes two first surfaces and two second surfaces. The two first surfaces are disposed opposite to each other along the thickness direction, and the two second surfaces are disposed opposite to each other along a direction perpendicular to the thickness direction. The second surfaces are connected to the two first surfaces. The area of ​​the first surface is greater than the area of ​​the second surface.

19. The battery according to any one of claims 1-18, wherein, The expansion pressure of the battery cell in the thickness direction is 1.5MPa-2.0MPa.

20. The battery according to any one of claims 1-19, wherein, The single-sided coating weight of the negative electrode film is 90 mg / 1540 mm². 2 Up to 170mg / 1540mm 2 110mg / 1540mm is available as an option. 2 Up to 150mg / 1540mm 2 .

21. The battery according to any one of claims 1-20, wherein, The compaction density of the negative electrode film at 100% SOC of the battery cell is 1.15 g / cm³. 3 Up to 1.36 g / cm 3 The option is 1.25g / cm³. 3 Up to 1.36 g / cm 3 .

22. The battery according to any one of claims 1-21, wherein, The porosity of the negative electrode is 27%-40%.

23. The battery according to any one of claims 1-22, wherein, The carbon-based material includes at least one of artificial graphite and natural graphite.

24. The battery according to any one of claims 1-23, wherein, The negative electrode active material also includes a silicon-based material, wherein the silicon element in the silicon-based material has a mass content of 0.3% to 10%, optionally 1% to 6%.

25. The battery according to claim 24, wherein, The silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

26. The battery according to any one of claims 1-25, wherein, The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the second negative electrode film layer is disposed between the first negative electrode film layer and the negative electrode current collector; The negative electrode active material includes a first negative electrode active material disposed on the first negative electrode film layer and a second negative electrode active material disposed on the second negative electrode film layer. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials.

27. The battery according to claim 26, wherein, The thickness ratio of the first negative electrode film layer to the thickness of the second negative electrode film layer is 3:7 to 7:3, and can be selected as 4:6 to 6:

4.

28. The battery according to claim 26 or 27, wherein, The thickness of the first negative electrode film is less than or equal to the thickness of the second negative electrode film.

29. The battery according to any one of claims 26-28, wherein, The volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material.

30. The battery according to any one of claims 26-29, wherein, The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and can be selected as 7.8 μm-11.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5μm-18.5μm, and can be selected as 9.5μm-14.6μm.

31. The battery according to any one of claims 1-30, wherein, The specific surface area of ​​the negative electrode active material is 0.5 m². 2 / g-3m 2 / g, optional 0.6m 2 / g-1.2m 2 / g.

32. The battery according to any one of claims 1-31, wherein, The single-sided coating weight of the positive electrode film is 200 mg / 1540 mm. 2 -370mg / 1540 / mm 2 ; 240mg / 1540mg is optional 2 Up to 330mg / 1540mm 2 .

33. The battery according to any one of claims 1-32, wherein, The compaction density of the positive electrode film at 100% SOC of the battery cell is 2.50 g / cm³. 3 Up to 2.80 g / cm 3 ; 2.55g / cm³ is optional 3 -2.70g / cm 3 .

34. The battery according to any one of claims 1-33, wherein, The porosity of the positive electrode is 25%-32%.

35. The battery according to any one of claims 1-34, wherein, The thickness of the positive electrode sheet is 0.13mm-0.2mm.

36. The battery according to any one of claims 1-35, wherein, The ratio of the thickness of the positive current collector to the thickness of the positive electrode film is 0.05-0.

3.

37. The battery according to any one of claims 1-36, wherein, The volume average particle size of the positive electrode active material satisfies 1μm≤Dv50≤2μm and 0.4μm≤Dv10≤0.7μm.

38. The battery according to any one of claims 1-37, wherein, The battery cell includes an electrolyte contained within the casing.

39. The battery according to claim 38, wherein, The electrolyte has a conductivity of 15 mS / cm to 20 mS / cm at room temperature.

40. The battery according to claim 38 or 39, wherein, The electrolyte includes an organic solvent, which includes one or more of carbonate solvents and carboxylic acid ester solvents.

41. The battery according to claim 40, wherein, The carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

42. The battery according to claim 40 or 41, wherein, The carboxylic acid ester comprises R1-COO-R2, wherein R1 and R2 each independently comprise an alkyl group having 1-5 carbon atoms or a haloalkyl group having 1-5 carbon atoms.

43. The battery according to any one of claims 38-42, wherein, The electrolyte comprises a lithium salt, which includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is from 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) is from 0.5 mol / L to 1.0 mol / L.

44. The battery according to any one of claims 38-43, wherein, The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

45. The battery according to any one of claims 1-44, wherein, The electrode assembly has a dimension of T along the thickness direction, the thickness of a single negative electrode sheet is T1, and the number of negative electrode sheets stacked in the thickness direction is N. T, T1, and N satisfy: 0.3≤(N×T1) / T≤0.

5.

46. ​​The battery according to any one of claims 1-45, wherein, The charging time for a single battery cell from 10% SOC to 80% SOC is 5 to 10.5 minutes.

47. An electrical appliance, characterized in that, Includes a battery according to any one of claims 1-46, the battery being used to provide electrical energy.

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