Battery and electrical device

Abstract

The present application provides a battery and an electrical device. The battery includes a plurality of battery cells and a box body. The plurality of battery cells are arranged along the thickness direction of the battery cell. The battery cell includes a housing and an electrode assembly accommodated in the housing. The box body is used to accommodate the plurality of battery cells, and the box body includes at least two limiting beams. Adjacent two limiting beams are respectively arranged on both sides of the plurality of battery cells along the thickness direction. The expansion pressure of the battery cell in the thickness direction is 0.5 MPa - 2.4 MPa. The limiting beam includes a first side facing the plurality of battery cells, and the first side is configured such that when subjected to a pressure of 1.7 MPa, the maximum displacement of the first side in the thickness direction is less than or equal to 8 mm.

Description

[0001] This application claims the priority of PCT International Application PCT / CN2024 / 102678 titled "Battery and Electrical Appliance" filed on June 28, 2024, the entire content of which is incorporated herein by reference. Technical Field

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

[0003] Batteries are widely used in electronic devices, such as mobile phones, laptop computers, battery-powered vehicles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0004] In the development of battery technology, how to improve the reliability of batteries is a research direction in battery technology. Summary of the Invention

[0005] This application provides a battery and an electrical appliance, which can improve the reliability of the battery.

[0006] In a first aspect, an embodiment of this application provides a battery, which includes a plurality of battery cells and a box body. The plurality of battery cells are arranged along the thickness direction of the battery cells. Each battery cell includes a housing and an electrode assembly accommodated in the housing. The box body is used to accommodate the plurality of battery cells. The box body includes at least two limiting beams, and two adjacent limiting beams are respectively arranged on both sides of the plurality of battery cells along the thickness direction. The expansion pressure of the battery cell in the thickness direction is 0.5 MPa - 2.4 MPa. The limiting beam includes a first side facing the plurality of battery cells, and the first side is configured such that: when subjected to a pressure of 1.7 MPa, the maximum displacement of the first side in the thickness direction is less than or equal to 8 mm.

[0007] The expansion pressure of the battery cell is related to the compactness of the electrode assembly. The limiting beam of the embodiment of this application has high strength, so that the battery cell can have an expansion pressure greater than or equal to 0.5 MPa in the thickness direction, thereby improving the compactness of the electrode assembly and increasing the energy density of the battery cell. The expansion pressure of the battery cell in the thickness direction is less than or equal to 2.4 MPa, and the limiting beam has high anti-deformation ability. Therefore, the limiting beam can provide effective constraint to the battery cell in the thickness direction to reduce the deformation of the electrode assembly during cycling, reduce the risk of wrinkling deformation of the separator of the electrode assembly and the risk of increased local spacing between the positive electrode sheet and the negative electrode sheet, reduce polarization, and improve the cycling performance of the battery cell. By controlling the expansion pressure of the battery cell within a reasonable range and correspondingly designing the limiting beam, this application can reduce the deformation of the battery cell and the limiting beam, reduce the risk of cracking of the box body, and improve the cycling performance of the battery cell.

[0008] In some embodiments, the expansion pressure of the battery cell in the thickness direction is 1.5 MPa - 2.0 MPa. This can reduce the deformation of the limiting beam, lower the risk of the box body cracking, and improve the cycle performance of the battery cell. Limiting the expansion pressure of the battery cell to 1.5 MPa - 2.0 MPa can also reduce the requirement for the strength of the limiting beam and lower the cost.

[0009] In some embodiments, the electrode assembly includes two first surfaces and two second surfaces. The two first surfaces are oppositely arranged in the thickness direction, the two second surfaces are oppositely arranged in a direction perpendicular to the thickness direction, and the second surfaces connect the two first surfaces. The area of the first surface is larger than the area of the second surface. Opposing the larger-area first surface to the first side surface in the thickness direction can increase the force-bearing area of the limiting beam when the battery assembly expands and reduce the deformation of the limiting beam.

[0010] In some embodiments, the first surface is parallel to the first side surface, which can reduce stress concentration when the electrode assembly expands, reduce the local deformation of the limiting beam, improve the consistency of the force on the electrode assembly, and enhance the cycle performance of the battery cell.

[0011] In some embodiments, the electrode assembly includes a negative electrode sheet, and the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material.

[0012] In some embodiments, the single-sided coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , and may be optionally 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 . The single-sided coating weight of the negative electrode film layer is related to the expansion of the negative electrode film layer. Limiting the single-sided coating weight of the negative electrode film layer within the above range can, to a certain extent, balance the energy density and expansion pressure of the battery cell and reduce the deformation of the battery cell and the limiting beam.

[0013] In some embodiments, the compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 , and may be 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 cell at 100% state of charge. Limiting the compaction density of the negative electrode film layer within the above range can, to a certain extent, balance the energy density and expansion pressure of the battery cell and reduce the deformation of the battery cell and the limiting beam.

[0014] In some embodiments, the porosity of the negative electrode sheet is 27% - 40%. The porosity of the negative electrode sheet being greater than or equal to 27% can provide space for impurities generated by side reactions in the negative electrode sheet, slow down the swelling of the negative electrode sheet, reduce the swelling pressure of the battery cell, decrease the deformation of the battery cell and the limiting beam, and improve the cycling performance of the battery cell. The porosity of the negative electrode sheet being less than or equal to 40% can take into account the energy density of the battery cell.

[0015] In some embodiments, the negative electrode active 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 fast charging performance of the battery cell.

[0016] In some embodiments, the negative electrode active material includes a silicon-based material, and the mass content of silicon element in the silicon-based material in the negative electrode active material is 0.3% to 10%, and can be selected as 1% to 6%. Introducing a silicon-based material into the negative electrode sheet can not only increase the capacity and the energy density of the battery cell, but also increase the swelling of the negative electrode sheet. Therefore, limiting the mass content of silicon element in the negative electrode active material to 0.3% to 10% can, to a certain extent, take into account the energy density and swelling of the battery cell, reduce the deformation of the battery cell and the limiting beam, and improve the cycling performance of the battery cell.

[0017] In some embodiments, the silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

[0018] 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 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 in the first negative electrode film layer and a second negative electrode active material disposed 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 silicon-based materials. The first negative electrode film layer and the second negative electrode film layer can be differentially set, so as to take into account the swelling and capacity of the negative electrode film layer to a certain extent; double-layer coating can construct pore differences in the negative electrode film layer, reduce the tortuosity of ion transport, reduce side reactions, and improve the fast charging performance of the battery cell.

[0019] In some embodiments, the ratio of the thickness 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. By adjusting the thickness ratio of the first negative electrode film layer and the second negative electrode film layer, the gradient pore difference between the upper and lower layers can be further increased, the tortuosity of lithium ion transport can be reduced, and the fast charging ability of the battery cell can be improved.

[0020] 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 fast charging ability of the battery cell.

[0021] 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.

[0022] There are differences in the particle sizes of the first negative electrode active material and the second negative electrode active material, which can improve the fast charging performance of the battery cell; during fast charging, the overpotential of the first negative electrode film layer is usually relatively high, and the bottleneck of fast charging mainly lies in the first negative electrode film layer. In the embodiments of the present 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 the fast charging performance, and can improve the problem of ion precipitation on the surface layer 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 layer. During charging, the pores can absorb expansion, reduce the expansion amount of the negative electrode film layer, and reduce the deformation of the battery cell and the limiting beam.

[0023] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm - 14.3 μm, and can be optionally 7.8 μm - 11.3 μm. The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, and can be optionally 9.5 μm - 14.6 μm.

[0024] Setting the volume average particle size Dv50 of the first negative electrode active material within the above range can, on the one hand, shorten the solid-phase transport path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material; on the other hand, the first negative electrode active material within the above volume average particle size range can cooperate with the second negative electrode active material, which is beneficial to constructing the gradient pore difference between the first negative electrode film layer and the second negative electrode film layer, reducing the tortuosity of lithium ion transport, and improving the fast charging performance of the battery cell. The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, which can make the pores of the second negative electrode film layer more abundant, be beneficial to improving the fast charging ability of the battery cell, and reduce the expansion of the negative electrode film layer during charging.

[0025] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g, and can be optionally 0.6 m 2 / g - 1.2 m 2 / g. Limiting the specific surface area of the negative electrode active material to be greater than or equal to 0.5 m 2 / g can improve the fast charging ability of the battery cell; limiting the specific surface area of the negative electrode active material to be less than or equal to 3 m 2 / g can reduce the side reactions during the storage of the battery cell and reduce the expansion pressure.

[0026] In some embodiments, the electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material is a lithium-containing phosphate. The lithium-containing phosphate has relatively high cycle stability. Using the lithium-containing phosphate as the positive electrode active material can improve the cycle attenuation of the battery cell caused by excessive temperature rise during fast charging.

[0027] In some embodiments, the single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 ; optionally 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2 。Setting the single-sided coating weight of the positive electrode film layer within the above range can limit the heat generation per unit area of the positive electrode sheet, and can take into account the improvement of the energy density and charging rate performance of the battery cell.

[0028] 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 to 2.80 g / cm 3 ; optionally 2.55 g / cm 3 -2.70 g / cm 3 。When the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and because the positive electrode active materials in the positive electrode film layer are stacked relatively tightly, the contact resistance between particles is small, which can further reduce the resistance of the positive electrode sheet, thereby reducing the heat generation during fast charging.

[0029] In some embodiments, the porosity of the positive electrode sheet is 25% - 32%. The porosity of the positive electrode sheet being greater than or equal to 25% can provide space for impurities generated by side reactions in the positive electrode sheet, reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell and the limiting beam, and improve the cycle performance of the battery cell. The porosity of the positive electrode sheet being less than or equal to 32% can take into account the energy density of the battery cell.

[0030] In some embodiments, the thickness of the positive electrode sheet is 0.13 mm - 0.2 mm. Using a positive electrode sheet with a smaller thickness can shorten the ion migration path, increase the ion migration rate, reduce the heat generation of the battery cell, and improve the fast charging performance of the battery cell.

[0031] In some embodiments, the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer is 0.05 - 0.3. Limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be greater than or equal to 0.05 can improve the current-carrying capacity of the positive current collector, reduce the temperature rise of the positive electrode sheet, and improve the fast charging performance of the battery cell; limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be less than or equal to 0.3 can reduce the loss of the capacity of the positive electrode sheet. In the embodiments of the present application, limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be between 0.05 and 0.3 can balance the fast charging ability and energy density of the battery cell to a certain extent.

[0032] In some embodiments, the volume-average particle size of the positive active material satisfies 1 µm ≤ Dv50 ≤ 2 µm, and 0.4 µm ≤ Dv10 ≤ 0.7 µm. The particle size of the positive active material is relatively small, the lithium deintercalation / lithiation path of lithium ions in the positive active material is short, and the heat generation is less; moreover, the particle size of the above positive active material is not too small, which can reduce agglomeration during the processing and preparation process, making the performance of the positive active material stable.

[0033] In some embodiments, the battery cell includes an electrolyte accommodated in a housing.

[0034] In some embodiments, the conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm. When the conductivity of the electrolyte is within the above range, the migration rate of ions in the electrolyte is relatively high, thereby further reducing the internal resistance of the battery cell, reducing heat generation, and improving the fast charging performance of the battery cell.

[0035] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents. The combination of organic solvents can improve the conductivity of the electrolyte and reduce the viscosity, thereby improving the fast charging performance of the battery.

[0036] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0037] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 each independently include an alkyl group having 1 - 5 carbon atoms or a haloalkyl group having 1 - 5 carbon atoms. The chain-like carboxylate solvent has a relatively high conductivity, which is beneficial to improving the fast charging ability of the battery cell.

[0038] In some embodiments, the electrolyte includes a lithium salt, the lithium salt includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) is 0.5 mol / L to 1.0 mol / L.

[0039] 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 within 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 cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0040] In some embodiments, the electrode assembly includes a negative electrode sheet; the size of the electrode assembly in the thickness direction is T, the thickness of the negative electrode sheet is T1, and the number of layers of the negative electrode sheet stacked in the thickness direction is N. T, T1, and N satisfy: 0.3 ≤ (N × T1) / T ≤ 0.5. During the cycling of the battery cell, the thickness of the negative electrode sheet increases due to irreversible side reactions, thereby causing the battery cell to expand; limiting (N × T1) / T to 0.3 - 0.5 can reduce the expansion of the battery cell and reduce the deformation of the limiting beam.

[0041] In some embodiments, the distance between two adjacent limiting beams in the thickness direction is D1. A plurality of battery cell columns are arranged between adjacent limiting beams, the plurality of battery cell columns are arranged in a direction perpendicular to the thickness direction, and each battery cell column includes at least two battery cells arranged in the thickness direction. The total size of the electrode assemblies of the battery cells in the battery cell column in the thickness direction is D2; 85% ≤ D2 / D1 ≤ 92%.

[0042] D2 / D1 is related to the expansion pressure exerted by the battery cell on the limiting beam. Limiting D2 / D1 to be less than or equal to 92% can reduce the expansion pressure of the battery cell, reduce the deformation of the limiting beam and the battery cell, and reduce the risk of the box body cracking; limiting D2 / D1 to be greater than or equal to 85% can improve the space utilization rate in the thickness direction and increase the energy density of the battery. Limiting D2 / D1 to 85% - 92% can balance the expansion pressure of the battery cell and the energy density of the battery to a certain extent.

[0043] In some embodiments, the limiting beam includes a second side surface, and the second side surface is located on the side of the limiting beam away from the plurality of battery cells and is inclined towards the first side surface.

[0044] When a force is exerted on the limiting beam due to expansion during the cycling of the battery cell, the second side can utilize the inclination to decompose the force, thereby improving the anti-deformation ability of the limiting beam and reducing the deformation or displacement of the first side; the first side can provide a strong constraint to the battery cell to reduce the expansion deformation of the battery cell and improve the cycling performance of the battery cell. Compared with the solution of improving the anti-deformation ability of the limiting beam by increasing the overall size of the limiting beam, the solution of using the inclined second side to increase the anti-deformation ability of the limiting beam can reduce the weight of the limiting beam and improve the energy density of the battery.

[0045] In some embodiments, the included angle α between the first side and the second side is 1° - 25°. Setting the included angle α to be greater than or equal to 1° can make the limiting beam have higher structural strength and stiffness and reduce the anti-deformation ability of the limiting beam. Setting the included angle α to be less than or equal to 25° can limit the maximum size of the limiting beam in the thickness direction, thereby saving space and improving the space utilization rate of the limiting beam in the thickness direction.

[0046] In some embodiments, the volumetric energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the included angle α between the first side and the second side is 5° - 20°. The expansion of the battery cell is related to its volumetric energy density. In this application, the included angle α is designed according to the volumetric energy density of the battery cell, so as to balance the requirements of the battery for expansion pressure and energy density to a certain extent.

[0047] In some embodiments, the volumetric energy density of the battery cell is 450 Wh / L - 480 Wh / L, and the included angle α between the first side and the second side is 8° - 25°. The battery cell has a higher energy density, and the expansion pressure of the battery cell is also greater; increasing the included angle α can enable the limiting beam to provide more binding force to the battery cell, thereby improving the cycling performance of the battery cell.

[0048] In some embodiments, the electrode assembly includes a negative electrode sheet. The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes at least one of a silicon oxide compound and a silicon-carbon composite. The included angle α between the first side and the second side is 8° - 25°.

[0049] By introducing a silicon oxide compound or a silicon-carbon composite, the capacity of the negative electrode sheet can be improved, and the energy density of the battery cell can be increased. Introducing a silicon oxide compound and a silicon-carbon composite will also increase the expansion of the negative electrode sheet during cycling. Setting the included angle α to 8° - 25° can improve the anti-deformation ability of the limiting beam, thereby providing a constraint for the expansion of the battery cell and reducing the risk of cycling decay of the battery cell caused by introducing a silicon oxide compound or a silicon-carbon composite.

[0050] In some embodiments, the limiting beam includes a third side surface, which is located on the side of the limiting beam away from the battery cell and is parallel to the first side surface, and the third side surface is connected to the second side surface. Through the third side surface, the maximum dimension of the limiting beam in the thickness direction can be limited, improving the space utilization rate. Through the combination of the third side surface and the second side surface, the limiting beam can also form a cross-section approximately in the shape of a trapezoid, thereby enhancing the structural strength and stiffness of the limiting beam and reducing the deformation of the limiting beam.

[0051] In some embodiments, the box body includes a frame body and a support beam. The frame body defines an accommodation space, and the limiting beam and a plurality of battery cells are arranged in the accommodation space. The support beam is arranged on the side of the limiting beam away from the plurality of battery cells and connects the frame body and the limiting beam.

[0052] During the cycling process of the battery, the limiting beam is used to resist the expansion force of the battery cell during the cycling process. The frame body can support the limiting beam through the support beam, thereby providing effective support for the limiting beam, reducing the deformation of the limiting beam, and further providing restraint to the battery cell, reducing the expansion of the battery cell, and improving the cycling life of the battery cell.

[0053] In some embodiments, the limiting beam extends in a direction perpendicular to the thickness direction. The box body includes a plurality of support beams arranged at intervals along the extension direction of the limiting beam. The plurality of support beams can increase the binding force received by the limiting beam, improve the uniformity of the force on different regions of the limiting beam, reduce the deformation of the limiting beam during the cycling process of the battery cell, and improve the cycling performance of the battery.

[0054] In some embodiments, the limiting beam further includes a second side surface and a third side surface. The third side surface is located on the side of the limiting beam away from the battery cell and is parallel to the first side surface. The second side surface is connected to one end of the third side surface and is inclined towards the first side surface. The support beam is connected to the third side surface. The third side surface is perpendicular to the thickness direction. Connecting the support beam to the third side surface can enable the support beam to effectively support the limiting beam in the thickness direction and reduce the deformation of the limiting beam.

[0055] In some embodiments, the limiting beam includes an outer wall and a plurality of reinforcing ribs. The outer wall encloses to form an accommodation cavity, and the plurality of reinforcing ribs are arranged in the accommodation cavity and connected to the outer wall. The outer wall includes a first side surface. The accommodation cavity can not only provide a deformation space for energy absorption for the limiting beam, but also reduce the overall weight of the limiting beam, which is beneficial to improving the energy density of the battery. The reinforcing ribs can improve the structural strength and stiffness of the limiting beam and enhance the anti-deformation ability of the limiting beam.

[0056] In some embodiments, the electrode assembly includes a negative electrode sheet, which includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material. The mass content of silicon element in the silicon-based material in the negative electrode active material is 1%-6%; the thickness of the outer wall is 2 mm - 7 mm, and the thickness of the reinforcing rib is 2 mm - 7 mm.

[0057] 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 increased. Introducing the silicon-based material will also increase the expansion of the negative electrode sheet during cycling. By designing the thickness of the outer wall and the thickness of the reinforcing rib in combination with the content of silicon element, the risk of deformation of the limiting beam caused by the introduction of the silicon-based material can be reduced, and the cycling performance of the battery can be improved.

[0058] In some embodiments, the outer wall includes a first side wall and a second side wall spaced apart in the thickness direction. The second side wall is located on the side of the first side wall away from the battery cell. The first side wall includes a first side surface. The plurality of reinforcing ribs include a first reinforcing rib connected to the first side wall. The expansion deformation of the battery cell during cycling will exert a force on the limiting beam, and the force is first applied to the first side wall. The first reinforcing rib is connected to the first side wall, which can transmit the force to other parts of the outer wall and form a support for the first side wall, thereby improving the anti-deformation ability of the first side wall.

[0059] In some embodiments, at least one first reinforcing rib is inclined relative to the thickness direction. The expansion deformation of the battery cell during cycling will exert a force on the first side wall, and the component force of the force in the thickness direction is relatively large; the first reinforcing rib inclined relative to the thickness direction can decompose the force, thereby reducing the risk of the first reinforcing rib being crushed.

[0060] In some embodiments, the limiting beam extends in a direction perpendicular to the thickness direction. At least two first reinforcing ribs are spaced apart in a direction perpendicular to both the extending direction of the limiting beam and the thickness direction, and are inclined in opposite directions relative to the thickness direction. Inclining at least two first reinforcing ribs in opposite directions can further improve the structural strength and stiffness of the limiting beam. When the first side wall is subjected to a force in the thickness direction, the torque directions of the two first reinforcing ribs are different, thereby reducing the risk of rotational deformation of the two first reinforcing ribs.

[0061] In some embodiments, the included angle between the first reinforcing rib and the thickness direction is 30° - 80°. Setting the included angle β at 30° - 80° can take into account the pressure and moment received by the first reinforcing rib to a certain extent, reduce the risk of the first reinforcing rib being crushed or undergoing rotational deformation, improve the structural strength and stiffness of the limiting beam, and provide an effective constraint for the battery cell.

[0062] In some embodiments, the first sidewall includes a middle region and two edge regions. In a direction parallel to the first side surface and perpendicular to the extending direction of the limiting beam, the two edge regions extend from both ends of the middle region, and the dimensions of the middle region and the edge regions are equal. At least one first reinforcing rib is connected to the middle region.

[0063] During the cycling of the battery cell, the center of the battery cell expands greatly along its own height direction, and the middle region of the first sidewall is opposite to the center of the battery cell. Therefore, the force received by the middle region is generally greater than the force received by the edge regions; connecting at least one first reinforcing rib to the middle region can provide support for the middle region to inhibit the expansion deformation of the battery cell during the cycling process.

[0064] In some embodiments, the outer wall includes a first sidewall and a second sidewall arranged at intervals in the thickness direction. The second sidewall is located on the side of the first sidewall away from the plurality of battery cells, and the first sidewall includes a first side surface. The second sidewall includes a first section and a second section. The first section is parallel to the first sidewall, and the second section extends from one end of the first section and is inclined towards the first sidewall. At least one reinforcing rib is connected to the connection between the first section and the second section.

[0065] During the cycling of the battery cell, the battery cell expands and applies a force to the first sidewall. A part of the force can be transmitted to the connection between the first section and the second section through the reinforcing rib, thereby dispersing the stress. Both the first section and the second section can support the first sidewall through the reinforcing rib to reduce the deformation of the first sidewall.

[0066] In some embodiments, the outer wall includes a first sidewall, a second sidewall, and a top wall. The second sidewall is located on the side of the first sidewall away from the plurality of battery cells, and the top wall connects the first sidewall and the second sidewall; the first sidewall includes a first side surface. The limiting beam further includes a partition wall connected to the top wall. In the thickness direction, the partition wall is located between the first sidewall and the second sidewall. At least one reinforcing rib connects the first sidewall and the partition wall, and at least one reinforcing rib connects the second sidewall and the partition wall.

[0067] By providing the partition wall and the reinforcing rib, a multi-chamber structure can be formed inside the limiting beam, which is beneficial to improving the overall stiffness of the limiting beam. During the cycling of the battery cell, the battery cell expands and applies a force to the first sidewall. The partition wall can transmit and disperse the force, thereby reducing the deformation of the first sidewall and constraining the battery cell.

[0068] In some embodiments, the limiting beam is an integrally formed structure. This can reduce the connection weak points of the limiting beam, which is beneficial to improving the structural strength and stiffness of the limiting beam.

[0069] In some embodiments, the battery further includes an insulating member disposed between the limiting beam and the housing. The insulating member can insulate the limiting beam from the housing, increase the creepage distance between the battery cell and the limiting beam, reduce the short-circuit risk, and improve the reliability.

[0070] In some embodiments, the battery further includes a constraining member that connects adjacent limiting beams. During the cycling of the battery cell, the battery cell expands and applies a force to the limiting beam. The constraining member can provide a constraining force to the limiting beam, thereby reducing the deformation of the limiting beam and restricting the expansion amount of the battery cell, improving the cycling performance of the battery cell, and reducing the risk of cracking of the box body.

[0071] In some embodiments, the constraining member is connected to the battery cell, which can increase the connection strength between the battery cell and the box body, reduce the shaking of the battery cell relative to the box body when the battery is impacted, and improve the reliability and stability of the battery.

[0072] In some embodiments, the constraining member is adhesively bonded to the battery cell. By means of adhesion, a stable connection between the battery cell and the constraining member can be quickly achieved, and the constraining force of the constraining member on the battery cell can be enhanced.

[0073] In some embodiments, the constraining member is detachably connected to the limiting beam. The detachable connection method can facilitate the later maintenance or replacement of the constraining member.

[0074] In some embodiments, the battery further includes a fixing member that connects the constraining member and the limiting beam. At least a part of the fixing member is embedded in the limiting beam and fixed to the limiting beam. The fixing member is embedded in the limiting beam, thereby enhancing the connection strength between the fixing member and the limiting beam and reducing the risk of connection failure between the fixing member and the limiting beam. The constraining member can be connected to the limiting beam through the fixing member, and the connection between the fixing member and the constraining member is not restricted by the limiting beam. In this way, the connection method between the fixing member and the constraining member can be flexibly selected according to needs, and the connection strength between the fixing member and the constraining member can be improved.

[0075] In some embodiments, the limiting beam has a receiving cavity inside, and the fixing member is received in the receiving cavity. By providing the receiving cavity, the fixing member can be integrally embedded into the limiting beam, improving the connection strength between the fixing member and the limiting beam.

[0076] In some embodiments, the limiting beam extends in a direction perpendicular to the thickness direction. There are multiple constraining members, and the multiple constraining members are arranged at intervals along the extending direction of the limiting beam. The multiple constraining members can increase the constraining force received by the limiting beam, improve the uniformity of the force on different regions of the limiting beam, reduce the deformation of the limiting beam during the cycling of the battery cell, and improve the cycling performance of the battery.

[0077] In some embodiments, the battery further includes a plurality of current collecting components that electrically connect a plurality of battery cells. The plurality of current collecting components includes at least one first current collecting component, and the first current collecting component includes a first current collecting layer and a second current collecting layer that are stacked and connected. The first current collecting layer is connected to at least two battery cells arranged in the thickness direction.

[0078] The first current collecting component has at least a double-layer structure, and both the first current collecting layer and the second current collecting layer of the first current collecting component can conduct current. In this way, the first current collecting component can have a relatively large current-carrying area, thereby reducing the heat generation of the first current collecting component and improving the fast charging ability of the battery. On the premise that the current-carrying area meets the requirements, setting the first current collecting component as a double-layer structure can reduce the thickness of the first current collecting layer. During the cycling process of the battery cell, it will expand, thereby stretching the first current collecting layer. The first current collecting layer has a relatively small thickness and is easy to deform to adapt to the deformation of the battery cell, reducing the risk that the connection between the battery cell and the first current collecting layer is torn, and improving the reliability of the battery.

[0079] In some embodiments, the battery cell includes an electrode terminal disposed on the outer casing, and the electrode terminal is electrically connected to the electrode assembly. The portion of the first current collecting layer that does not overlap with the second current collecting layer is connected to the electrode terminal. The second current collecting layer can avoid the connection between the first current collecting layer and the electrode terminal, thereby reducing the influence of the second current collecting layer on the connection between the first current collecting layer and the electrode terminal when the battery cell expands, reducing the risk that the connection between the electrode terminal and the first current collecting layer is torn, and improving the reliability of the battery.

[0080] In some embodiments, the first current collecting component includes at least one bending portion that connects the first current collecting layer and the second current collecting layer. The bending portion can connect the first current collecting layer and the second current collecting layer and conduct current between the first current collecting layer and the second current collecting layer, thereby improving the current-carrying capacity of the first current collecting component.

[0081] In some embodiments, the first current collecting layer includes a first current collecting portion, a second current collecting portion, and a first buffer portion connecting the first current collecting portion and the second current collecting portion. The first current collecting portion and the second current collecting portion are arranged in the thickness direction and are connected to different battery cells. The bending portion and the first buffer portion are arranged to avoid each other.

[0082] During the cycling process of the battery cell, the battery cell expands and applies a pulling force to the first current collecting layer; the first buffer portion can release stress through deformation, thereby reducing the force at the connection between the first current collecting portion and the battery cell and the force at the connection between the second current collecting portion and the battery cell, reducing the risk of connection failure between the first current collecting layer and the battery cell. 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.

[0083] In some embodiments, the second current collecting layer includes a first stacked portion, a second stacked portion, and a second buffer portion. The first stacked portion is stacked with the first current collecting portion and connected through at least one bent portion. The second stacked portion is stacked with the second current collecting portion and connected through at least one bent portion. The second buffer portion connects the first stacked portion and the second stacked portion. In the stacking direction of the first current collecting layer and the second current collecting layer, the second buffer portion at least partially overlaps with the first buffer portion.

[0084] During the cycling of the battery cell, the battery cell expands and applies a tensile force to the first current collecting layer; both the first buffer portion and the second buffer portion can release stress through deformation, thereby reducing the risk of connection failure between the first current collecting layer and the battery cell. The second buffer portion at least partially overlaps with the first buffer portion, so that the deformation regions of the first buffer portion and the second buffer portion are close, thereby reducing the risk of interference between the first buffer portion and the second buffer portion and other parts during deformation.

[0085] In some embodiments, the second buffer portion and the first buffer portion are disposed in a fitting manner, which can save space.

[0086] In some embodiments, the plurality of current collecting components further includes at least one second current collecting component, and the thickness of the second current collecting component is greater than the thickness of the first current collecting layer and greater than the thickness of the second current collecting layer.

[0087] In the battery, the expansion amounts of the battery cells at different positions may vary. For the battery cells with a small expansion amount, a second current collecting component with a single-layer structure can be used; compared with the first current collecting component, the second current collecting component has a simple structure, is easy to manufacture, and can save costs. The thickness of the second current collecting component is greater than the thickness of the first current collecting layer and the thickness of the second current collecting layer, and its current-carrying capacity can meet the requirements.

[0088] In some embodiments, the sum of the thickness of the first current collecting layer and the thickness of the second current collecting layer is equal to the thickness of the second current collecting component, which can reduce the difference in current-carrying capacity between the first current collecting component and the second current collecting component and improve the current consistency.

[0089] In some embodiments, the battery cells adjacent to the limiting beam are connected to the first current collecting component. During the charging process, the expansions of the plurality of battery cells may be superimposed in the thickness direction, resulting in a relatively large displacement of the battery cells adjacent to the limiting beam; using a first current collecting component with a double-layer structure to connect the battery cells near the limiting beam can reduce the risk of connection failure between the first current collecting component and the battery cells.

[0090] In some embodiments, the thickness of the first current collecting layer is 1 mm - 2.5 mm, and may be optionally 1.2 mm - 1.8 mm. Selecting the thickness of the first current collecting layer according to the expansion pressure of the battery cell can balance the current-carrying capacity and deformability of the first current collecting layer to a certain extent, thereby improving the fast charging capacity and reliability of the battery.

[0091] In some embodiments, the thickness of the second current collecting layer is 1 mm - 2.5 mm.

[0092] In some embodiments, the volumetric energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the thickness of the first current collecting layer is less than or equal to 2.5 mm; or, the volumetric energy density of the battery cell is 450 Wh / L - 480 Wh / L, and the thickness of the first current collecting layer is less than or equal to 2.2 mm.

[0093] The expansion of the battery cell is related to its volumetric energy density. In this application, the thickness of the first current collecting layer is designed according to the volumetric energy density of the battery cell, so as to balance the current-carrying capacity and deformability of the first current collecting layer to a certain extent, thereby improving the fast charging capacity and reliability of the battery.

[0094] In some embodiments, the electrode assembly includes a negative electrode sheet, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material. The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% - 6%; the thickness of the first current collecting layer is 1.2 mm - 2.2 mm, and the thickness of the second current collecting layer is 1.2 mm - 2.2 mm.

[0095] 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 increased. Introducing the silicon-based material will also increase the expansion of the negative electrode sheet during cycling. Designing the thicknesses of the first current collecting layer and the second current collecting layer in combination with the content of silicon element can reduce the risk of connection failure between the first current collecting layer and the battery cell caused by the introduction of the silicon-based material, and meet the requirements for the current-carrying capacity of the first current collecting component.

[0096] In some embodiments, the first current collecting layer includes a first current collecting portion, a second current collecting portion, and a first buffer portion connecting the first current collecting portion and the second current collecting portion. The first current collecting portion and the second current collecting portion are disposed along the thickness direction and are connected to different battery cells. In the stacking direction of the first current collecting layer and the second current collecting layer, the first buffer portion protrudes from the first current collecting portion and the second current collecting portion. The first current collecting layer is provided with a concave portion at a position corresponding to the first buffer portion. By providing the concave portion, the strength of the first buffer portion can be reduced, facilitating the deformation of the first buffer portion when the battery cell expands.

[0097] In some embodiments, the volumetric energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the depth of the recess is 1.2 mm - 2.5 mm; alternatively, the volumetric energy density of the battery cell is 450 Wh / L - 480 Wh / L, and the depth of the recess is 1 mm - 2.2 mm.

[0098] The expansion of the battery cell is related to its volumetric energy density. In this 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 and deformability of the first buffer part to a certain extent, thereby improving the fast charging ability and reliability of the battery.

[0099] In some embodiments, it takes 5 minutes to 10.5 minutes for the battery cell to be charged from 10% SOC to 80% SOC. The battery cell has the ability of fast charging, which can save charging time.

[0100] In a second aspect, an embodiment of the present application provides an electrical device, which includes the battery provided in any one of the embodiments of the first aspect, and the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0102] Figure 1 It is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0103] Figure 2 It is a schematic diagram of a battery provided in some embodiments of the present application;

[0104] Figure 3 It is an exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0105] Figure 4 It is a schematic diagram of a battery provided in some embodiments of the present application;

[0106] Figure 5 It is Figure 4 A cross-sectional schematic diagram taken along the A-A direction;

[0107] Figure 6 It is Figure 5 An enlarged schematic diagram at the square box;

[0108] Figure 7 It is Figure 3 A schematic diagram of the electrode assembly described;

[0109] Figure 8 is Figure 7 a schematic cross-sectional view of the electrode assembly shown;

[0110] Figure 9 a schematic cross-sectional view of the negative electrode sheet of a battery cell provided by some embodiments of the present application;

[0111] Figure 10 a schematic cross-sectional view of the negative electrode sheet of a battery cell provided by other embodiments of the present application;

[0112] Figure 11 a schematic cross-sectional view of the positive electrode sheet of a battery cell provided by some embodiments of the present application;

[0113] Figure 12 provided by some embodiments of the present application Figure 2 a partial cross-sectional view of the battery at the circular frame;

[0114] Figure 13 provided by yet other embodiments of the present application Figure 2 a partial cross-sectional view of the battery at the circular frame;

[0115] Figure 14 a schematic structural view of a battery provided by other embodiments of the present application;

[0116] Figure 15 is Figure 14 a partial cross-sectional view of the battery shown;

[0117] Figure 16 is Figure 4 an enlarged view at the circular frame;

[0118] Figure 17 is Figure 16 a schematic structural view of the first current collecting member shown;

[0119] Figure 18 a schematic connection view of a battery cell and the first current collecting member provided by some embodiments of the present application;

[0120] Figure 19 a top view of a battery provided by other embodiments of the present application;

[0121] Figure 20 is Figure 19 an enlarged view at the square frame;

[0122] Figure 21 is Figure 20 a schematic structural view of the second current collecting member in.

[0123] The reference numerals are explained as follows

[0124] 1. Vehicle; 2. Battery; 3. Controller; 4. Motor;

[0125] 10. Battery cell; 100. Battery cell column; 10a. Large face; 10b. Narrow face;

[0126] 11. Electrode assembly; 111. Positive electrode sheet; 1111. Positive current collector; 1112. Positive electrode film layer; 112. Negative electrode sheet; 1121. Negative 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; 11b. Positive electrode tab; 11c. Negative electrode tab; 11d. First surface; 11e. Second surface; 11f. Third surface;

[0127] 12. Outer shell; 121. Housing; 122. End cap; 13. Electrode terminal;

[0128] 20. Box body;

[0129] 21. Limiting beam; 211. Outer wall; 2111. First side wall; 21111. Middle region; 21112. Edge region; 2112. Second side wall; 21121. First section; 21122. Second section; 2113. Top wall; 2114. Bottom wall; 212. Reinforcing rib; 212a. First reinforcing rib; 212b. Second reinforcing rib; 213. Accommodating cavity; 214. Partition wall; 2141. Third section; 2142. Fourth section; 21a. First side; 21b. Second side; 21c. Third side;

[0130] 22. Frame body; 23. Support beam; 24. Bearing plate;

[0131] 30. Insulating part; 40. Restraining part; 50. Adhesive layer; 60. Fixing part;

[0132] 70. Busbar component; 70a. First busbar component; 70b. Second busbar component; 70c. Third busbar component; 71. First busbar layer; 711. First busbar part; 712. Second busbar part; 713. First buffer part; 714. Recess; 72. Second busbar layer; 721. First stacked part; 722. Second stacked part; 723. Second buffer part; 73. Bending part;

[0133] 80. Fastener;

[0134] X. Thickness direction; Y. Extension direction; Z. Height direction. Detailed implementation mode

[0135] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0136] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used in the description of this application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above drawings are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0137] Referring to "embodiments" in this application means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0138] In the description of this application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "coupled", and "attached" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0139] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the associated objects before and after.

[0140] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width, and other dimensions of various components shown in the drawings in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device, are only for illustrative purposes and should not constitute any limitation to this application.

[0141] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are understood to be anticipated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all anticipated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0142] The term "a plurality of" as used in this application refers to two or more (including two).

[0143] "Parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism that is conventionally recognized in engineering. "Perpendicular" includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity that is conventionally recognized in engineering.

[0144] Currently, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only applied to energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, but also widely applied to electric transportation means such as electric bicycles, electric motorcycles, and electric vehicles, as well as multiple fields such as aerospace. With the continuous expansion of the application fields of batteries, the market demand for them is also continuously increasing.

[0145] A battery generally refers to a single physical module that includes a plurality of battery cells to provide a higher voltage and capacity. A battery cell is the smallest unit that makes up a battery. During the cycling process of the battery cell, an electrochemical reaction occurs inside, causing the battery cell to expand. As the battery cell continuously expands, it will affect the overall performance of the battery.

[0146] Based on this, in order to limit the expansion of the battery cell, a battery generally has a limiting beam to support and restrain the battery cell. The restraint of the limiting beam on the battery cell will affect the cycling performance of the battery cell.

[0147] In view of this, an embodiment of the present application provides a battery, which rationally designs the battery cell and the limiting beam to effectively limit the expansion of the battery cell and improve the cycling performance of the battery cell.

[0148] The battery described in the embodiments of the present application is applicable to electric devices using batteries. The electric 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 electric device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. Among them, the electric toy can include a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, and an electric aircraft toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, and a spaceship, etc.

[0149] For the convenience of description, the following embodiments take the electric device as a vehicle as an example for description.

[0150] Figure 1 It is a schematic structural diagram of a vehicle provided by some embodiments of the present application.

[0151] As Figure 1 shown, a battery 2 is arranged inside the vehicle 1, and the battery 2 can be arranged at the bottom, head or 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 the operating power source of the vehicle 1.

[0152] The vehicle 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery 2 to supply power to the motor 4. For example, it is used for the working power requirements during the start, navigation and driving of the vehicle 1.

[0153] In some embodiments of the present application, the battery 2 can not only be used as the operating power source of the vehicle 1, but also be used as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0154] Figure 2 It is a schematic diagram of a battery provided by some embodiments of the present application.

[0155] Referring to Figure 2 , in some embodiments, the battery 2 includes a box body 20 and a plurality of battery cells 10 accommodated in the box body 20.

[0156] The battery cell 10 can be a secondary battery, and a secondary battery refers to a battery cell that can be activated by charging after discharging the battery cell and can be used continuously.

[0157] Exemplarily, 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-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0158] As an 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 includes a square shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc.

[0159] Multiple battery cells 10 can be connected in series, in parallel or in a combined series-parallel connection. A combined series-parallel connection means that there are both series and parallel connections among multiple battery cells 10. Multiple battery cells 10 can be directly connected in series, in parallel or in a combined series-parallel connection together, and then the whole formed by multiple battery cells 10 is accommodated in the box body 20; of course, it can also be that multiple battery cells 10 are first connected in series, in parallel or in a combined series-parallel connection to form battery modules, and then multiple battery modules are connected in series, in parallel or in a combined series-parallel connection to form a whole and are accommodated in the box body 20.

[0160] In some embodiments, the box body 20 can be a part of the chassis structure of a vehicle. For example, a part of the box body 20 can become at least a part of the floor of the vehicle, or a part of the box body 20 can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0161] Figure 3 This is an explosion schematic diagram of the battery cell provided in some embodiments of the present application.

[0162] Refer to Figure 3 , in some embodiments, the battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12.

[0163] The housing 12 is a hollow structure, and an accommodation space for accommodating the electrode assembly 11 and the electrolyte is formed inside it. 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.

[0164] As an example, the housing 12 includes a housing body 121 and an end cap 122. The housing body 121 has an opening, and the end cap 122 is used to cover the opening.

[0165] The housing body 121 is a component for cooperating with the end cap 122 to form the internal cavity of the battery cell 10. The formed internal cavity can be used to accommodate the electrode assembly 11, the electrolyte and other components.

[0166] The housing 121 and the end cap 122 can be independent components. Exemplarily, an opening can be provided on the housing 121, and the end cap 122 is covered at the opening to form the internal cavity of the battery cell 10.

[0167] The housing 121 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 121 can be determined according to the specific shape and size of the electrode assembly 11. The material of the housing 121 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not make special restrictions on this.

[0168] The shape of the end cap 122 can be adapted to the shape of the housing 121 to cooperate with the housing 121. The material of the end cap 122 can be the same as or different from the material of the housing 121. Optionally, the end cap 122 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 122 is not easily deformed when being squeezed and collided, enabling the battery cell 10 to have higher structural strength and improved reliability.

[0169] The end cap 122 is connected to the housing 121 by welding, bonding, clamping or other means.

[0170] One end of the housing 121 can be open, or both ends can be open. In some examples, the housing 121 can be a structure with one side open, and the end cap 122 is provided as one and covers the housing 121. In other examples, the housing 121 can also be a structure with both sides open, and the end caps 122 are provided as two, and the two end caps 122 respectively cover the two openings of the housing 121.

[0171] The electrode assembly 11 is a component in the battery cell 10 where an electrochemical reaction occurs. The housing 121 can contain one or more electrode assemblies 11.

[0172] In some embodiments, the electrode assembly 11 includes a positive electrode plate and a negative electrode plate. During the charging and discharging process of the battery cell 10, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate.

[0173] As an example, the parts of the positive electrode plate and the negative electrode plate with active substances constitute the main body part 11a of the electrode assembly 11, the part of the positive electrode plate without active substances constitutes the positive electrode tab 11b, and the part of the negative electrode plate without active substances constitutes the 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 part 11a together or at both ends of the main body part 11a respectively.

[0174] In some embodiments, the electrode assembly 11 further includes a separator membrane disposed between the positive electrode sheet and the negative electrode sheet, which can prevent short circuit between the positive and negative electrodes and allow active ions to pass through.

[0175] In some embodiments, the electrode assembly 11 is in a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0176] In some embodiments, the electrode assembly 11 is in a stacked structure.

[0177] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately stacked.

[0178] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet is folded to form a plurality of stacked folding segments, and a positive electrode sheet is clamped between adjacent folding segments.

[0179] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folding segments.

[0180] As an example, a plurality of separator membranes may be provided and disposed between any adjacent positive electrode sheet or negative electrode sheet respectively.

[0181] As an example, the separator membrane may be continuously provided and disposed between any adjacent positive electrode sheet or negative electrode sheet by folding or winding.

[0182] In some embodiments, the battery cell 10 further includes an electrode terminal 13 disposed on the outer casing 12; the electrode terminal 13 can be used to electrically connect to the electrode assembly 11 to input or output electrical energy.

[0183] In some embodiments, the electrode terminal 13 is electrically connected to the tab. Exemplarily, there are two electrode terminals 13, and the two electrode terminals 13 are respectively electrically connected to the positive tab 11b and the negative tab 11c.

[0184] Figure 4 Schematic diagram of the battery provided by some embodiments of the present application; Figure 5 is Figure 4 A cross-sectional schematic diagram taken along the A-A direction; Figure 6 is Figure 5 An enlarged schematic diagram at the square box; Figure 7 is Figure 3 The schematic diagram of the said electrode assembly; Figure 8 is Figure 7 The cross-sectional schematic diagram of the shown electrode assembly.

[0185] Referring to Figures 4 to 8, embodiments of the present application provide a battery 2, which includes a plurality of battery cells 10 and a box body 20. The plurality of battery cells 10 are arranged along the thickness direction X of the battery cells 10. The battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12. The box body 20 is used to accommodate the plurality of battery cells 10. The box body 20 includes at least two limiting beams 21, and two adjacent limiting beams 21 are respectively arranged on both sides of the plurality of battery cells 10 along the thickness direction X. The expansion pressure of the battery cell 10 in the thickness direction X is 0.5 MPa - 2.4 MPa. The limiting beam 21 includes a first side surface 21a facing the plurality of battery cells 10, and the first side surface 21a is configured such that: when subjected to a pressure of 1.7 MPa, the maximum displacement of the first side surface 21a in the thickness direction X is less than or equal to 8 mm.

[0186] The battery cells 10 between two adjacent limiting beams 21 can be arranged in a row or in multiple rows. Exemplarily, a row of battery cells 10 can form a battery cell row 100, and the battery cell row 100 includes at least two battery cells 10 arranged along the thickness direction X.

[0187] The battery cell 10 may include one or more electrode assemblies 11. Optionally, the electrode assemblies 11 are arranged along the thickness direction X.

[0188] Optionally, the expansion pressure of the battery cell 10 in the thickness direction X is 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.

[0189] As an example, the expansion pressure of the battery cell 10 can be measured in the following manner:

[0190] In an ambient temperature of 45°C, discharge the battery cell 10 at a constant current discharge rate of 1C until 2.0V;

[0191] Clamp the battery cell 10 between two clamping plates, where the two clamping plates are respectively located on both sides of the battery cell 10 along the thickness direction X and cover the large surface 10a (the large surface 10a is the surface on one side of the battery cell 10 along the thickness direction X);

[0192] In an ambient temperature of 45°C, charge the battery cell at a constant current charge rate of 0.8C until 3.8V, and detect and record the pressure exerted by the battery cell on the clamping plate;

[0193] Perform cyclic charge and discharge on the battery cell according to the above charging strategy and charging 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;

[0194] Calculate the expansion pressure Q of the battery cell in the thickness direction as: the maximum pressure / the large surface area.

[0195] There may be two or more limiting beams 21. As an example, at least one battery cell row 100 is provided between any two adjacent limiting beams 21.

[0196] 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 against the battery cell 10 in the thickness direction X; alternatively, other components can also be provided between the limiting beam 21 and the battery cell 10, that is, the limiting beam 21 restricts the expansion of the battery cell 10 through this component.

[0197] Exemplarily, the first side surface 21a of the limiting beam 21 can be a vertical plane for facing the large surface of the battery cell 10.

[0198] Exemplarily, the maximum displacement E of the first side surface 21a of the limiting beam 21 in the thickness direction under a pressure of 1.7 MPa can be measured in the following manner:

[0199] (Ⅰ) Remove the battery cell 10 of the battery 2 and fix the battery box 20 of the battery 2 to the fixture;

[0200] (Ⅱ) Make the indenter of the pressure testing machine abut against the first side surface 21a of the limiting beam 21, wherein the pressing surface of the indenter abutting against the first side surface 21a is the same as the large surface 10a of the battery cell 10;

[0201] (Ⅲ) Apply a constant force F to the indenter and move the indenter along the thickness direction X of the battery cell 10, and record the maximum displacement E of the indenter. Exemplarily, the area of the pressing surface is S, and F / S is 1.7 MPa.

[0202] As an example, when the indenter abuts against the middle region of the first side surface 21a along the extension direction Y of the limiting beam 21, the maximum displacement of the first side surface 21a in the thickness direction X is less than or equal to 8 mm.

[0203] The expansion pressure of the battery cell 10 is related to the compactness of the electrode assembly 11. The limiting beam in the embodiment of the present application has a high strength, so that the battery cell 10 can 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 increasing 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, and the limiting beam 21 has a high anti-deformation ability. Therefore, the limiting beam 21 can effectively constrain the battery cell 10 in the thickness direction X to reduce the deformation of the electrode assembly 11 during cycling, reduce the risk of wrinkling deformation of the separator of the electrode assembly 11 and the risk of increased local spacing between the positive electrode sheet and the negative electrode sheet, reduce polarization, and improve the cycling performance of the battery cell 10. By controlling the expansion pressure of the battery cell within a reasonable range and correspondingly designing the limiting beam 21, the present application can reduce the deformation of the battery cell 10 and the limiting beam, reduce the risk of cracking of the box body 20, and improve the cycling performance of the battery cell 10.

[0204] In some embodiments, the electrode assembly 11 includes 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 surfaces 11e connect the two first surfaces 11d. The area of the first surface 11d is larger than the area of the second surface 11e.

[0205] Opposing the larger-area first surface 11d to the first side surface 21a along the thickness direction X can increase the force-bearing area of the limiting beam 21 and reduce the deformation of the limiting beam 21 when the electrode assembly 11 expands.

[0206] In some embodiments, the first surface 11d is parallel to the first side surface 21a, which can reduce stress concentration when the electrode assembly 11 expands, reduce local deformation of the limiting beam 21, improve the consistency of the force on the electrode assembly 11, and enhance the cycling performance of the battery cell 10.

[0207] In the embodiment of the present application, "parallel" includes not only the case of absolute parallelism but also the case of approximately parallelism commonly recognized in engineering. In a battery, due to manufacturing tolerances, displacement and deformation of the battery cell during cycling, etc., the first surface 11d and the first side surface 21a may fluctuate. Exemplarily, when the included angle between the first surface 11d and the first side surface 21a is within 0° - 5°, the first surface 11d and the first side surface 21a can be considered parallel.

[0208] In some embodiments, along the extension direction Y of the limiting beam 21, the two second surfaces 11e are oppositely arranged. The extension direction Y of the limiting beam 21 can be perpendicular to the thickness direction X. Exemplarily, the extension direction Y of the limiting beam 21 is the length direction of the limiting beam 21.

[0209] In some embodiments, the main body portion 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 in the height direction Z, and the third surfaces 11f are connected to the two first surfaces 11d and the two second surfaces 11e.

[0210] 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 third surfaces 11f respectively.

[0211] In some embodiments, at least a part 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.

[0212] In some embodiments, the outer surface of the battery cell 10 includes two large surfaces 10a and two narrow surfaces 10b, the two large surfaces 10a are oppositely arranged along the thickness direction X, the two narrow surfaces 10b are oppositely arranged along the extension direction Y, and both ends of the large surface 10a in the extension direction Y are connected to the two narrow surfaces 10b. The area of the large surface 10a is larger than the area of the narrow surface 10b.

[0213] In some embodiments, the large surface 10a, the first side surface 21a, and the first surface 11d are parallel.

[0214] In some embodiments, the battery cell 10 is a square shell battery cell. Optionally, the narrow surface 10b is perpendicular to the large surface 10a.

[0215] In some embodiments, the expansion pressure of the battery cell 10 in the thickness direction X is 1.5 MPa - 2.0 MPa.

[0216] In the embodiments of the present application, the expansion pressure of the battery cell 10 in the thickness direction X is limited to 1.5 MPa - 2.0 MPa to reduce the deformation of the limiting beam 21, reduce the risk of cracking of the box body 20, and improve the cycle performance of the battery cell 10.

[0217] Limiting the expansion pressure of the battery cell 10 to 1.5 MPa - 2.0 MPa can reduce the requirement for the strength of the limiting beam 21 and reduce the cost.

[0218] Figure 9 It is a cross-sectional view schematic diagram of the negative electrode sheet of the battery cell provided in some embodiments of the present application.

[0219] Refer to Figure 8 and Figure 9, in some embodiments, the electrode assembly 11 includes a negative electrode sheet 112, and 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 includes a negative electrode active material.

[0220] In the embodiments of the present application, the negative electrode film layer 1122 may be disposed on only one side of the negative electrode current collector 1121, or the negative electrode film layer 1122 may be disposed on both sides of the negative electrode current collector 1121.

[0221] Optionally, negative electrode film layers 1122 are provided on both surfaces of the negative electrode current collector 1121 that are opposite to each other 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 may be made of the same negative electrode active material or different negative electrode active materials; the thicknesses of the negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 may be the same or different.

[0222] In some embodiments, a part of the negative electrode current collector 1121 is not covered by the negative electrode film layer 1122; the part of the negative electrode current collector 1121 not covered by the negative electrode film layer 1122 can be used to form a negative electrode tab 11c.

[0223] In some embodiments, the negative electrode current collector 1121 may be a metal foil or a composite current collector. As an example of the metal foil, at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy foils may be used. The composite current collector may 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 may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0224] 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 a range composed of any two of the above values.

[0225] In some embodiments, the compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 . Exemplarily, when the battery cell is at 100% state of charge, the compaction density of the negative electrode film layer 1122 is 1.15 g / cm 3 、1.18 g / cm 3, 1.20 g / cm 3 , 1.22 g / cm 3 , 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 composed of any two of the above values.

[0226] Exemplarily, 100% SOC (state of charge) and 0% SOC are defined as follows:

[0227] Charge the battery cell at a constant current charge rate of 0.33C to the upper limit voltage of battery charging, and then charge at a constant voltage until 0.05C, corresponding to the state of 100% SOC of the battery cell; discharge the battery cell at a constant current discharge rate of 0.33C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell. Exemplarily, the upper limit voltage of battery charging can be 3.8V; the cut-off voltage of battery discharge can be 2.0V.

[0228] Exemplarily, the compaction density of the negative electrode film layer of the battery cell in the 100% charged state has the meaning well-known in the art, that is, disassemble the negative electrode sheet of the battery cell at 100% SOC and measure the compaction density of the negative electrode film layer; for example, take 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), punch it into small round pieces with an area of S1, weigh it, record it as M1, and measure its thickness H1. Then wipe off the negative electrode film layer of the above weighed negative electrode sheet, weigh the weight of the negative electrode current collector, record it as M0, and measure its thickness H0. The single-sided coating weight of the negative electrode film layer = (the weight M1 of the negative electrode sheet - the weight M0 of the negative electrode current collector) / S1, the thickness of the negative electrode film layer = the thickness H1 of the negative electrode sheet - the thickness H0 of the negative electrode current collector, 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.

[0229] The compaction density of the negative electrode film layer 1122 is related to the swelling of the battery cell 10 in the 100% charged state. Limiting the compaction density of the negative electrode film layer 1122 to 1.15 g / cm 3 to 1.36 g / cm 3 can, to a certain extent, balance the energy density and swelling pressure of the battery cell 10 and reduce the deformation of the battery cell 10 and the limiting beam 21.

[0230] When the compaction density of the negative electrode film layer 1122 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and since the negative electrode active materials in the negative electrode film layer 1122 are stacked relatively tightly, the contact resistance between particles is small, which can reduce the resistance of the negative electrode sheet 112, thereby reducing heat generation.

[0231] When the compaction density of the negative electrode film layer 1122 is within the above range, the fast charging ability of the battery cell 10 can be improved. When the compaction density of the negative electrode film layer 1122 is small, the porosity of the negative electrode sheet 112 can be increased, the swelling of the negative electrode sheet can be slowed down, and the swelling pressure of the battery cell 10 can be reduced.

[0232] In some embodiments, the compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.25 g / cm 3 to 1.36 g / cm 3 , which can improve the energy density of the battery cell 10.

[0233] 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 . Exemplarily, 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 composed of any two of the above values.

[0234] The single-sided coating weight of the negative electrode film layer 1122 is related to the swelling of the negative electrode film layer. Limiting the single-sided coating weight of the negative electrode film layer 1122 to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 can, to a certain extent, take into account the energy density and swelling pressure of the battery cell 10, and reduce the deformation of the battery cell 10 and the limiting beam 21.

[0235] In addition, limiting the single-sided 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 amount per unit area of the negative electrode sheet 112, and reduce the temperature rise of the battery cell 10, especially the temperature rise during rapid charging.

[0236] In some embodiments, the single-sided coating weight of the negative electrode film layer 1122 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 to further take into account the energy density and swelling pressure of the battery cell 10.

[0237] In some embodiments, the porosity of the negative electrode sheet 112 is 27% - 40%. As an 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%.

[0238] The porosity of the negative electrode sheet can be the percentage of the pore volume in the negative electrode sheet to the total volume of the negative electrode sheet. Exemplarily, when the battery cell is in the 0% state of charge, a double-sided coated negative electrode sheet is taken; the AccuPyc Ⅱ 1340 true density meter is used to measure the porosity of the negative electrode sheet in accordance with the national standard GB / T 24586 - 2009.

[0239] 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 in 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 and the limiting beam 21, and improve the cycling performance of the battery cell 10. The porosity of the negative electrode sheet 112 is less than or equal to 40%, which can take into account the energy density of the battery cell 10.

[0240] In some embodiments, the negative electrode active material includes a carbon-based material. Optionally, the carbon-based material includes graphite particles, and the graphitization degree of the graphite particles is 92.0% to 94.5%. Exemplarily, the graphitization degree of the graphite particles is 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5% or any range composed of any two of the above values.

[0241] When the graphitization degree of the graphite particles is within 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 can improve the fast charging performance of the battery cell 10.

[0242] In some embodiments, the negative electrode active material includes at least one of artificial graphite and natural graphite. The artificial graphite and natural graphite have good conductive performance, which can reduce the heat generation of the negative electrode sheet 112 during charging and improve the fast charging performance of the battery cell 10.

[0243] In some embodiments, the negative electrode active material 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.

[0244] In some embodiments, the mass content of silicon element in the silicon-based material in the negative electrode active material is from 0.3% to 10%. Exemplarily, the mass content of 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 the range composed of any two of the above values.

[0245] Introducing the silicon-based material into the negative electrode sheet 112 can not only improve the capacity but also increase the expansion of the negative electrode sheet 112. Therefore, limiting the mass content of silicon element in the negative electrode active material to be from 0.3% to 10% can, to a certain extent, balance the energy density and expansion of the battery cell 10, reduce the deformation of the battery cell 10 and the limiting beam 21, and improve the cycling performance of the battery cell 10.

[0246] In some embodiments, the mass content of silicon element in the silicon-based material in the negative electrode active material is from 1% to 6%.

[0247] The qualitative and quantitative determination of each substance or each element in this application can be detected by 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 some detection steps / instrument parameters, etc. 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.

[0248] For example, the silicon-based material can be combined with the general rules of X-ray diffraction analysis method in JIS / K0131-1996 to perform X-ray powder diffraction test and qualitative analysis on the negative electrode sheet or the negative electrode active material.

[0249] In some embodiments, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.

[0250] In some embodiments, the silicon-based material includes at least one of silicon oxide compound and silicon-carbon composite.

[0251] In some embodiments, in addition to the carbon-based material and the optional silicon-based material, the negative electrode active material may further include at least one of tin-based material and lithium titanate. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.

[0252] 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 be a single-layer film layer or at least two-layer film layers. Optionally, the negative electrode film layer 1122 includes at least two-layer film layers.

[0253] When the negative electrode film layer 1122 is a single-layer film layer, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. When a single-layer film layer is used, the volume average particle diameter Dv50 of the negative electrode active material is 8.2 μm to 13.5 μm. Exemplarily, the volume average particle diameter 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 the range composed of any two of the above values.

[0254] When the negative electrode film layer 1122 is at least two-layer film layers, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. The silicon-based material can be located in one of the at least two-layer film layers or in at least two of the at least two-layer film layers. The negative electrode film layer 1122 can include two-layer film layers, three-layer film layers, four-layer film layers, or even more film layers.

[0255] Figure 10 It is a cross-sectional schematic view of the negative electrode sheet of the battery cell provided in other embodiments of the present application.

[0256] Refer to Figure 10 , 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. The second negative electrode film layer 11222 is disposed 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 disposed in the first negative electrode film layer 11221 and a second negative electrode active material disposed in the second negative electrode film layer 11222. 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.

[0257] The interface between the first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be regular or irregular; optionally it is irregular.

[0258] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be set differently, so as to balance the swelling and capacity of the negative electrode film layer 1122 to a certain extent; double-layer coating can construct the pore difference of the negative electrode film layer 1122, reduce the ion transport tortuosity, reduce side reactions, and improve the fast charging performance of the battery cell 10.

[0259] Artificial graphite can have a relatively small volume average particle size Dv50. On the one hand, it can shorten the solid-phase transport path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material.

[0260] In some embodiments, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is from 3:7 to 7:3. Optionally, 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. Optionally, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is from 4:6 to 6:4.

[0261] 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 ion transport tortuosity can be reduced, and the fast charging ability of the battery cell 10 can be improved.

[0262] 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 fast charging ability of the battery cell 10.

[0263] In some embodiments, the first negative electrode active material is granular, and the second negative electrode active material is granular.

[0264] 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.

[0265] There are differences in the particle sizes of the first negative electrode active material and the second negative electrode active material, which can improve the fast charging performance of the battery cell 10; during fast charging, the overpotential of the first negative electrode film layer 11221 is usually relatively high, and the bottleneck of fast charging mainly lies in the first negative electrode film layer 11221. In the embodiments of the present 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 the fast charging performance, and can 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. During charging, the pores can absorb expansion, reduce the expansion amount of the negative electrode film layer 1122, and reduce the deformation of the battery cell 10 and the limiting beam 21.

[0266] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm - 14.3 μm, and can be optionally 7.8 μm - 11.3 μm. Exemplarily, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm, 8.0 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.3 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, 13.8 μm, 14 μm, 14.1 μm, 14.3 μm or the range composed of any two of the above values.

[0267] The volume average particle size Dv50 of the first negative electrode active material is set to 7.8 μm - 14.3 μm. On the one hand, it can shorten the solid-phase transport path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material; on the other hand, the first negative electrode active material within the above volume average particle size range can cooperate with the second negative electrode active material, which is beneficial to constructing the gradient pore difference between the first negative electrode film layer 11221 and the second negative electrode film layer 11222, reducing the tortuosity of lithium ion transport, and improving the fast charging performance of the battery cell 10.

[0268] 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. It can be detected by using the equipment and methods well-known in the art. For example, taking the negative electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer.

[0269] In some embodiments, the volume-average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, and can be optionally 9.5 - 14.6 μm.

[0270] Exemplarily, the volume-average particle size Dv50 of the second negative electrode active material is 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 14.6 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm or the range composed of any two of the above values.

[0271] The volume-average particle size Dv50 of the second negative electrode active material being in the range of 9.5 μm - 18.5 μm can make the pores of the second negative electrode film layer 11222 richer, which is beneficial to improving the fast charging ability of the battery cell 10 and reducing the swelling of the negative electrode film layer 1122 during charging.

[0272] In some embodiments, the first negative electrode active material includes graphite particles, and the volume-average particle size Dv50 of the graphite particles in the first negative electrode film layer 11221 is 7.8 μm to 14.3 μm, and can be optionally 7.8 μm to 11.3 μm. Optionally, the first negative electrode active material includes artificial graphite.

[0273] The second negative electrode active material includes graphite particles, and the volume-average particle size Dv50 of the graphite particles is 9.5 μm to 18.5 μm, and can be optionally 9.5 μm to 14.6 μm. Optionally, the second negative electrode active material includes natural graphite.

[0274] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g, and can be optionally 0.6 m 2 / g - 1.2 m 2 / g. Exemplarily, the specific surface area of the negative electrode 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 m2 / 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 composed of any two of the above values.

[0275] The specific surface area of the material has the meaning well-known in the art and can be detected by equipment and methods well-known in the art. For example, it can be detected according to the test standard GB / T 19587-2017. Taking the negative electrode active material as a sample, the specific surface area is tested by a Tri-Star 3020 specific surface area and pore size analyzer of Micromeritics Company, USA.

[0276] In the embodiments of the present application, the specific surface area of the negative electrode active material is limited to be greater than or equal to 0.5 m 2 / g, which can improve the fast charging ability of the battery cell 10; the specific surface area of the negative electrode active material is limited to be less than or equal to 3 m 2 / g, which can reduce the side reactions during the storage of the battery cell 10, slow down the expansion of the negative electrode sheet, and reduce the expansion pressure.

[0277] Figure 11 It is a cross-sectional view schematic diagram of the positive electrode sheet of the battery cell provided by some embodiments of the present application.

[0278] Referring to Figure 8 and Figure 11 , the electrode assembly 11 includes a positive electrode sheet 111, and the positive electrode sheet 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.

[0279] For example, the positive electrode current collector 1111 has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer 1112 is provided on any one or both of the two opposite surfaces of the positive electrode current collector 1111.

[0280] In some embodiments, the positive electrode film layer 1112 includes a positive electrode active material, and the positive electrode active material is a lithium-containing phosphate. The lithium-containing phosphate has relatively high cycle stability. Using the lithium-containing phosphate as the positive electrode active material can improve the cycle attenuation caused by excessive temperature rise during the fast charging process of the battery cell 10.

[0281] In some embodiments, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 ; optionally 2.55 g / cm 3 -2.70 g / cm 3 . Exemplarily, when the battery cell 10 is at 100% state of charge (SOC), the compaction density of the positive electrode film layer 1112 is 2.50 g / cm 3 , 2.52 g / cm 3 , 2.55 g / cm 3 , 2.56 g / cm 3 , 2.57 g / cm 3 , 2.58 g / cm 3 , 2.60 g / cm 3 , 2.62 g / cm 3 , 2.65 g / cm 3 , 2.68 g / cm 3 , 2.70 g / cm 3 , 2.72 g / cm 3 , 2.75 g / cm 3 , 2.78 g / cm 3 , 2.80 g / cm 3 or the range composed of any two of the above values.

[0282] When the compaction density of the positive electrode film layer 1112 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and since the positive active materials in the positive electrode film layer 1112 are stacked relatively tightly and the contact resistance between particles is small, the resistance of the positive electrode sheet 111 can be further reduced, thereby reducing the heat generation during fast charging.

[0283] In the embodiments of the present application, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell has the meaning well known in the art, that is, the positive electrode sheet 111 is disassembled from the battery cell 10 at 100% SOC, and the compaction density of the positive electrode film layer 1112 is measured. Exemplarily, the test method for the compaction density of the positive electrode film layer 1112 can be the same as that of the negative electrode film layer 1122.

[0284] 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 ; optionally 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2Exemplarily, 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.

[0285] In the embodiments of the present application, the single-sided coating weight of the positive electrode film layer 1112 has the meaning well-known in the art, and can be detected by equipment and methods well-known in the art. The detection method is the same as the single-sided coating weight test method of the negative electrode film layer 1122 described above.

[0286] Set the single-sided coating weight of the positive electrode film layer 1112 at 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 , which can limit the heat generation per unit area of the positive electrode sheet 111 and can balance the improvement of the energy density and charging rate performance of the battery cell 10.

[0287] In some embodiments, the porosity of the positive electrode sheet 111 is 25%-32%. As an example, the porosity of the positive electrode sheet 111 can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32% or a range composed of any two of the above values.

[0288] In the embodiments of the present application, the porosity of the positive electrode sheet 111 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. Its detection method is the same as that of the porosity test of the negative electrode sheet 112.

[0289] The porosity of the positive electrode sheet 111 is greater than or equal to 25%, which can provide space for the impurities generated by the side reactions of the positive electrode sheet 111, reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell 10 and the limiting beam 21, and improve the cycling performance of the battery cell 10. The porosity of the positive electrode sheet 111 is less than or equal to 32%, which can take into account the energy density of the battery cell 10.

[0290] In some embodiments, the thickness of the positive electrode sheet 111 can be 0.13 mm - 0.2 mm. As an 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 the range composed of any two of the above values.

[0291] In the embodiments of the present application, the thickness of the positive electrode sheet 111 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. For example, a micrometer can be used to measure the thickness of the positive electrode sheet 111.

[0292] Using a positive electrode sheet 111 with a smaller thickness can shorten the ion migration path, increase the ion migration rate, reduce the heat generation of the battery cell 10, and improve the fast charging performance of the battery cell 10.

[0293] 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. Exemplarily, 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.

[0294] Exemplarily, 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 the range composed of any two of the above values.

[0295] Limiting the thickness ratio of the positive current collector 1111 to the thickness of the positive film layer 1112 to be greater than or equal to 0.05 can improve the current capacity of the positive current collector 1111, reduce the temperature rise of the positive electrode sheet 111, and improve the fast charging performance of the battery cell 10; limiting the thickness ratio of the positive current collector 1111 to the thickness of the positive film layer 1112 to be less than or equal to 0.3 can reduce the capacity loss of the positive electrode sheet 111. In the embodiment of the present application, the thickness ratio of the positive current collector 1111 to the thickness of the positive film layer 1112 is limited to 0.05 to 0.3, which can take into account the fast charging capability and energy density of the battery cell 10 to a certain extent.

[0296] The thickness of the positive electrode film layer and the thickness of the positive electrode current collector are well known in the art and can be detected by equipment and methods well known in the art. For example, the thickness of the positive electrode sheet is measured using a micrometer, and the film layer on the surface of the positive electrode current collector is removed, and the thickness of the positive electrode current collector is measured using a micrometer. When the positive electrode film layer is coated on one side, 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 coated on both sides, 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.

[0297] In some embodiments, the thickness of the positive current collector 1111 is 10 μm to 15 μm, and can be 12 μm to 15 μm. Exemplarily, the thickness of the positive 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 consisting of any two of the above values. When the thickness of the positive current collector 1111 is within the above range, the positive current collector 1111 has excellent current flow capacity and can enable the battery cell 10 to have a higher energy density.

[0298] In some embodiments, a portion of the positive electrode current collector 1111 is not covered by the positive electrode film layer 1112 ; the portion of the positive electrode current collector 1111 not covered by the positive electrode film layer 1112 can be used to form a positive electrode tab 11 b .

[0299] In some embodiments, the positive electrode active material includes an olivine-structured lithium-containing phosphate or a modified material thereof.

[0300] The lithium-containing phosphate with an olivine structure or its modified material can be the lithium-containing phosphate with an olivine structure, or a material obtained by coating and modifying the lithium-containing phosphate with an olivine structure. For example, the lithium-containing phosphate with an olivine structure includes phosphate particles and an ion-conducting layer, the ion-conducting layer coats the phosphate particles, and the ion-conducting layer contains one or more elements selected from C, Fe, Ti, Zr, Hf, Ge, and Sn.

[0301] In some embodiments, the mass percentage of the lithium-containing phosphate with olivine structure or its modified material in the positive electrode active material can be greater than or equal to 80% and less than or equal to 100%. It can be considered that the positive electrode active material of the present application is a system of lithium-containing phosphate with olivine structure or its modified material. When the mass percentage of the lithium-containing phosphate with olivine structure or its modified material is less than 100%, the positive electrode active material can further include common positive electrode active materials, such as at least one of lithium-containing transition metal oxides, for example, but 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 their respective modified compounds.

[0302] Optionally, the mass percentage of the lithium-containing phosphate with olivine structure or its modified material in the positive electrode active material is 100%.

[0303] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1 µm ≤ Dv50 ≤ 2 µm and 0.4 µm ≤ Dv10 ≤ 0.7 µm.

[0304] Exemplarily, 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 composed of any two of the above values.

[0305] Exemplarily, 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 composed of any two of the above values.

[0306] The particle size of the positive electrode active material is relatively small, the lithium deintercalation / insertion path of lithium ions in the positive electrode active material is short, and the heat generation is less; moreover, the particle size of the above positive electrode active material is not too small, which can reduce agglomeration during the processing and preparation process, making the performance of the positive electrode active material stable.

[0307] 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. It can be detected by using equipment and methods well-known in the art. For example, taking the positive electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer.

[0308] In some embodiments, the battery cell 10 includes an electrolyte accommodated in a housing 12. During the charging and discharging process of the battery cell 10, active ions are inserted into and extracted from between the positive electrode plate 111 and the negative electrode plate 112, and the electrolyte plays a role in conducting the active ions between the positive electrode plate 111 and the negative electrode plate 112.

[0309] In some embodiments, the conductivity of the electrolyte at room temperature is 13 mS / cm to 20 mS / cm, and may be optionally 15 mS / cm to 20 mS / cm. Exemplarily, the conductivity of the electrolyte at room temperature is 13 mS / cm, 13.5 mS / cm, 14 mS / cm, 14.5 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 16.5 mS / cm, 17 mS / cm, 17.5 mS / cm, 18 mS / cm, 18.5 mS / cm, 19 mS / cm, 19.5 mS / cm, 20 mS / cm or a range composed of any two of the above values.

[0310] As an example, the room temperature may be 25 °C.

[0311] When the conductivity of the electrolyte is within the above range, the migration rate of ions in the electrolyte is relatively high, thereby further reducing the internal resistance of the battery cell 10, reducing heat generation, and being able to improve the fast charging performance of the battery cell 10.

[0312] The conductivity of the electrolyte is the ionic conductivity, and it can be detected by using equipment and methods well-known in the art. For example, it can be tested with reference to the industry standard HG-T 4067-2015.

[0313] In some embodiments, the density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

[0314] Exemplarily, the density ρ 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 composed of any two of the above values.

[0315] When the density ρ of the electrolyte is within 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 cell 10, thereby reducing heat generation, and being able to improve the fast charging performance of the battery cell 10.

[0316] In the embodiments of the present application, the density of the electrolyte has the meaning well-known in the art, and it can be detected by using equipment and methods well-known in the art. For example, it can be tested with reference to GB / T 2013-2010.

[0317] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents.

[0318] In some embodiments, the carboxylate solvent includes a chain carboxylate solvent, and the mass content of the chain carboxylate solvent in the organic solvent is 5% to 75%. The mass content of the chain carboxylate solvent is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or a range composed of any two of the above values. When the mass content of the chain carboxylate solvent is within the above range, the viscosity of the electrolyte system is relatively small, which is beneficial to the migration of lithium ions.

[0319] In some embodiments, the mass content of the chain carboxylate solvent in the organic solvent is 30% to 70%.

[0320] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 each independently include an alkyl group with 1-5 carbon atoms or a haloalkyl group with 1-5 carbon atoms. The above chain carboxylate solvent has a relatively high conductivity, which is beneficial to improving the fast charging ability of the battery cell 10.

[0321] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0322] Further optionally, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0323] The above carbonate solvent and chain carboxylate solvent are used in combination, which improves the conductivity of the electrolyte and is beneficial to the migration of lithium ions.

[0324] Further optionally, the mass content of the carbonate solvent in the organic solvent is 5% to 95%, optionally 25% to 60%, and optionally 30% to 45%. Exemplarily, the mass content of the carbonate 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 composed of any two of the above values. The carbonate solvent with the above mass content can further improve the conductivity of the electrolyte and is beneficial to the migration of lithium ions.

[0325] Exemplarily, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the mass content of the carbonate solvent is 25% to 60%.

[0326] The combination of organic solvents can improve the conductivity of the electrolyte and reduce the viscosity, thereby enhancing the fast charging performance of Battery 2.

[0327] In some embodiments, the electrolyte includes a lithium salt. The lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate LiPF6. The above lithium salts are easy to dissociate, which is beneficial to the rapid migration of lithium ions; and the electrolyte system is relatively stable and not easily decomposed, which can improve the cycling performance of Battery Cell 10.

[0328] Optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0329] In some embodiments, the lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. The molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.4 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.7 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.8 mol / L.

[0330] Optionally, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate LiPF6 is (2 to 5):10. Exemplarily, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide 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 composed of any two of the above values.

[0331] Referring back to Figures 4 to 10 , in some embodiments, the electrode assembly 11 includes a negative electrode sheet 112; the size of the electrode assembly 11 in the thickness direction X is T, the thickness of the negative electrode sheet 112 is T1, and the number of layers of the negative electrode sheet 112 stacked in the thickness direction X is N. T, T1, and N satisfy: 0.3 ≤ (N×T1) / T ≤ 0.5.

[0332] At least one of the negative electrode sheets 112 includes a flat layer 112a perpendicular to the thickness direction X, and the number of layers of the flat layer 112a in the electrode assembly 11 is N.

[0333] Exemplarily, the battery cell 10 is disassembled at 0% state of charge, and the electrode assembly 11 is taken out; a micrometer is used to measure T and T1.

[0334] Exemplarily, the electrode assembly 11 is of a wound structure, and the negative electrode sheet 112 includes N flat layers 112a; alternatively, the electrode assembly 11 is of a stacked structure, the electrode assembly 11 includes N negative electrode sheets 112, and each negative electrode sheet 112 includes one flat layer 112a.

[0335] During the cycling of the battery cell 10, the thickness of the negative electrode sheet 112 increases due to irreversible side reactions, thereby causing the battery cell 10 to expand; limiting (N×T1) / T to 0.3 - 0.5 can reduce the expansion of the battery cell 10 and reduce the deformation of the limiting beam 21.

[0336] In some embodiments, the distance between two adjacent limiting beams 21 in the thickness direction X is D1. A plurality of battery cell columns 100 are provided between the adjacent limiting beams 21, the plurality of battery cell columns 100 are arranged in a direction perpendicular to the thickness direction X, and each battery cell column 100 includes at least two battery cells 10 arranged in the thickness direction X. The total dimension of the electrode assemblies 11 of the battery cells 10 in the battery cell column 100 in the thickness direction X is D2; 85% ≤ D2 / D1 ≤ 92%.

[0337] Exemplarily, the first side surfaces 21a of two adjacent limiting beams 21 are arranged opposite to each other, and D1 is the minimum distance between the first side surfaces 21a of the two limiting beams 21 in the thickness direction X. The first side surface 21a is perpendicular to the thickness direction X.

[0338] Exemplarily, D1 is measured at the position where the limiting beam 21 overlaps with the battery cell 10 in the thickness direction.

[0339] Exemplarily, the plurality of battery cell columns 100 are arranged along the extending direction Y of the limiting beam 21.

[0340] Exemplarily, the battery cell column 100 includes K1 battery cells 10, and each battery cell 10 includes K2 electrode assemblies 11 stacked in the thickness direction X; when the battery cell 10 is at 0% SOC, the dimension of the electrode assembly 11 in the thickness direction X is T; D2 = K1×K2×T; K1 is a positive integer greater than 1, and K2 is a positive integer.

[0341] D2 / D1 is related to the expansion pressure exerted by the battery cell 10 on the limiting beam 21. In the embodiments of the present application, D2 / D1 is limited to be less than or equal to 92% to reduce the expansion pressure of the battery cell 10, reduce the deformation of the limiting beam 21 and the battery cell 10, and reduce the risk of cracking of the box body 20; D2 / D1 is limited to be greater than or equal to 85% to improve the space utilization rate in the thickness direction X and increase the energy density of the battery 2. When D2 / D1 is limited to 85%-92%, the expansion pressure of the battery cell 10 and the energy density of the battery 2 can be taken into account to a certain extent.

[0342] In some embodiments, the limiting beam 21 includes a second side surface 21b, and the second side surface 21b is located on the side of the limiting beam 21 away from the plurality of battery cells 10 and is inclined toward the first side surface 21a.

[0343] When the battery cell 10 exerts a force on the limiting beam 21 due to expansion during the cycling process, the second side surface 21b can use the inclination to decompose the force, thereby improving the anti-deformation ability of the limiting beam 21 and reducing the deformation or displacement of the first side surface 21a; the first side surface 21a can provide a strong constraint to the battery cell 10 to reduce the expansion deformation of the battery cell 10 and improve the cycling performance of the battery cell 10. Compared with the solution of improving the anti-deformation ability of the limiting beam 21 by increasing the overall size of the limiting beam 21, the solution of using the inclined second side surface 21b to increase the anti-deformation ability of the limiting beam 21 can reduce the weight of the limiting beam 21 and increase the energy density of the battery 2.

[0344] In some embodiments, the included angle α between the first side surface 21a and the second side surface 21b is 1°-25°. As an example, α can be, but is not limited to, 1°, 2°, 3°, 5°, 6°, 8°, 10°, 12°, 15°, 18°, 20°, 21°, 23° or 25°.

[0345] Setting the included angle α to be greater than or equal to 1° can make the limiting beam 21 have higher structural strength and stiffness and reduce the anti-deformation ability of the limiting beam 21. Setting the included angle α to be less than or equal to 25° can limit the maximum size of the limiting beam 21 in the thickness direction X, thereby saving space and increasing the space utilization rate of the limiting beam 21 in the thickness direction X.

[0346] In some embodiments, the volume energy density of the battery cell 10 is 390 Wh / L - 450 Wh / L, and the included angle α between the first side surface 21a and the second side surface 21b is 5°-20°.

[0347] In the embodiments of the present application, the volume energy density of the battery cell 10 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art.

[0348] The swelling of the battery cell 10 is related to its volumetric energy density. In this application, the angle α is designed according to the volumetric energy density of the battery cell 10, so as to balance the requirements of the battery 2 for swelling pressure and energy density to a certain extent.

[0349] In some embodiments, the volumetric energy density of the battery cell 10 is 450 Wh / L - 480 Wh / L, and the angle α between the first side 21a and the second side 21b is 8° - 25°.

[0350] The swelling of the battery cell 10 is related to its volumetric energy density. In this application, the angle α is designed according to the volumetric energy density of the battery cell 10, so as to balance the requirements of the battery 2 for swelling pressure and energy density to a certain extent.

[0351] The battery cell 10 of the embodiments of this application has a higher energy density, and the swelling pressure of the battery cell 10 is also greater; increasing the angle α can enable the limiting beam 21 to provide more restraint force for the battery cell 10, thereby improving the cycling performance of the battery cell 10.

[0352] In some embodiments, the electrode assembly 11 includes a negative electrode sheet 112. The negative electrode sheet 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 includes a negative electrode active material, and the negative electrode active material includes at least one of a silicon oxide compound and a silicon-carbon composite. The angle α between the first side 21a and the second side 21b is 8° - 25°.

[0353] By introducing a silicon oxide compound or a silicon-carbon composite, the capacity of the negative electrode sheet 112 can be improved, and the energy density of the battery cell 10 can be increased. Introducing a silicon oxide compound and a silicon-carbon composite will also increase the swelling of the negative electrode sheet 112 during cycling. Setting the angle α to 8° - 25° can improve the anti-deformation ability of the limiting beam 21, thereby providing restraint for the swelling of the battery cell 10 and reducing the risk of cycling decay of the battery cell 10 caused by the introduction of a silicon oxide compound or a silicon-carbon composite.

[0354] In some embodiments, the limiting beam 21 is an integrally formed structure, which can reduce the connection weak points of the limiting beam 21 and is beneficial to improving the structural strength and stiffness of the limiting beam 21. Alternatively, the limiting beam 21 can also be formed by splicing multiple components. For example, the limiting beam 21 is formed by welding multiple sheet metal parts.

[0355] In some embodiments, the limiting beam 21 is a profile beam.

[0356] The limiting beam 21 can be a hollow beam structure formed by a plate or a rod through stamping / extrusion or metal casting. The wall thickness of the limiting beam 21 can be 1mm-8mm according to actual needs, and 3mm-5mm is more common. With this wall thickness, the limiting beam 21 has a good cost performance, and can have a light weight and good structural strength, which can effectively suppress the expansion deformation of the battery cell 10 during the cycle.

[0357] The limiting beam 21 can be made of, but is not limited to, steel, iron, aluminum, and aluminum alloy.

[0358] In some embodiments, the box 20 includes a frame 22 and a support beam 23. The frame 22 defines a storage space, and the limiting beam 21 and multiple battery cells 10 are arranged in the storage space. The support beam 23 is arranged on the side of the limiting beam 21 away from the multiple battery cells 10 and connects the frame 22 and the limiting beam 21.

[0359] Optionally, the frame 22 may be a rectangular frame.

[0360] The number of the supporting beam 23 may be one or more.

[0361] For two adjacent limiting beams 21 , one limiting beam 21 may be connected to the supporting beam 23 , or both limiting beams 21 may be connected to the supporting beam 23 .

[0362] During the cycle of the battery 2, the limiting beam 21 is used to resist the expansion force of the battery cell 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 constraints to the battery cell 10, reducing the expansion of the battery cell 10, and improving the cycle life of the battery cell 10.

[0363] By providing the supporting force connecting the frame 22 and the limiting beam 21 , the overall structural strength and rigidity of the box body 20 can be improved, and the risk of cracking of the box body 20 can be reduced.

[0364] In some embodiments, the frame 22 includes a plurality of side beams, which are sequentially arranged and connected to form an annular frame 22 .

[0365] 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 may be rectangular, trapezoidal, elliptical, circular, L-shaped or other shapes.

[0366] In some embodiments, the support beam 23 is a plate or hollow beam structure. The support beam 23 can be made of steel, aluminum or aluminum alloy.

[0367] In some embodiments, the support beam 23 and the housing 22 may be fixedly connected by welding, bolt connection, snap connection or the like.

[0368] In some embodiments, the limiting beam 21 extends in a direction perpendicular to the thickness direction X. The housing 20 includes a plurality of support beams 23 arranged at intervals along the extending direction Y of the limiting beam 21. The plurality of support beams 23 can increase the binding force received by the limiting beam 21, improve the uniformity of the force 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.

[0369] In some embodiments, the battery 2 further includes an insulating member 30 disposed between the limiting beam 21 and the outer shell 12. The insulating member 30 can insulate and isolate the limiting beam 21 from the outer shell 12, increase the creepage distance between the battery cell 10 and the limiting beam 21, reduce the short - circuit risk, and improve the reliability.

[0370] In some embodiments, the insulating member 30 is bonded to at least one of the outer shell 12 and the limiting beam 21.

[0371] Figure 12 This is a partial cross - sectional schematic view of the battery provided in other embodiments of the present application.

[0372] Refer to Figure 12 , in some embodiments, the limiting beam 21 includes a third side surface 21c, the third side surface 21c is located on the side of the limiting beam 21 away from the battery cell 10 and is parallel to the first side surface 21a, and the third side surface 21c is connected to the second side surface 21b.

[0373] Through the third side surface 21c, the maximum dimension of the limiting beam 21 in the thickness direction X can be limited, improving the space utilization rate. Through the combination of the third side surface 21c and the second side surface 21b, the limiting beam 21 can also form a cross - section approximately in the shape of a trapezoid, thereby enhancing the structural strength and stiffness of the limiting beam 21 and reducing the deformation of the limiting beam 21.

[0374] As an example, the second side surface 21b is connected to one end of the third side surface 21c and is inclined toward the first side surface 21a.

[0375] In some embodiments, the housing 20 further includes a carrier plate 24, and a plurality of battery cells 10 and limiting beams 21 are located on the same side of the carrier plate 24 and are fixed to the carrier plate 24. Exemplarily, the carrier plate 24 and the plurality of battery cells 10 are arranged along the height direction Z of the battery cell 10.

[0376] In some embodiments, the housing 20 further includes a cover plate (not shown), the cover plate is disposed opposite to the carrier plate 24 along the height direction Z and is fixed to the housing 22. The battery cell and the limiting beam are located between the cover plate and the carrier plate.

[0377] In some examples, the carrier plate 24 is located on the upper side of the battery cell, and the battery cell is inverted; alternatively, in some other examples, the carrier plate 24 is located on the lower side of the battery cell, and the battery cell is upright.

[0378] In some embodiments, both the third side surface 21c and the first side surface 21a are vertical planes.

[0379] In some embodiments, the second side surface 21b extends from one end of the third side surface 21c away from the carrier plate 24 and is inclined toward the first side surface 21a.

[0380] In some embodiments, the support beam 23 is connected to the third side surface 21c. The third side surface 21c is perpendicular to the thickness direction X. Connecting the support beam 23 to the third side surface 21c can enable the support beam 23 to effectively support the limiting beam 21 in the thickness direction X and reduce the deformation of the limiting beam 21.

[0381] In addition, setting the third side surface 21c as a vertical plane can facilitate the connection between the limiting beam 21 and the support beam 23 and simplify the structure of the support beam 23.

[0382] In some embodiments, the limiting beam 21 includes an outer wall 211 and a plurality of reinforcing ribs 212. The outer wall 211 encloses to form a receiving cavity 213, and the plurality of reinforcing ribs 212 are disposed in the receiving cavity 213 and connected to the outer wall 211. The outer wall 211 includes the first side surface 21a.

[0383] Exemplarily, the outer wall 211 further includes the second side surface 21b. Optionally, the outer wall 211 further includes the third side surface 21c.

[0384] Exemplarily, both the reinforcing ribs 212 and the outer wall 211 extend along the extending direction Y of the limiting beam 21.

[0385] The receiving cavity 213 can not only provide an energy-absorbing deformation space for the limiting beam 21, but also reduce the overall weight of the limiting beam 21, which is beneficial to improving the energy density of the battery 2. The reinforcing ribs 212 can improve the structural strength and stiffness of the limiting beam 21 and enhance the anti-deformation ability of the limiting beam 21.

[0386] In some embodiments, the electrode assembly 11 includes a negative electrode sheet 112. 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 includes a negative electrode active material, and the negative electrode active material includes a silicon-based material; the mass content of silicon element in the silicon-based material in the negative electrode active material is 1% - 6%; the thickness of the outer wall 211 is 2 mm - 7 mm, and the thickness of the reinforcing ribs 212 is 2 mm - 7 mm.

[0387] As an example, the mass content of silicon element in the silicon-based material in the negative electrode active material is 1%, 2%, 3%, 4%, 5% or 6%. As an example, the thickness of the outer wall 211 is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm. As an example, the thickness of the outer wall 211 is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm.

[0388] By introducing the silicon-based material, the capacity of the negative electrode sheet 112 can be improved, and the energy density of the battery cell 10 can be increased. Introducing the silicon-based material will also increase the expansion of the negative electrode sheet 112 during the cycling process. By designing the thickness of the outer wall 211 and the thickness of the reinforcing rib 212 in combination with the content of the silicon element, the risk of deformation of the limiting beam 21 caused by the introduction of the silicon-based material can be reduced, and the cycling performance of the battery 2 can be improved.

[0389] In some embodiments, the outer wall 211 includes a first side wall 2111 and a second side wall 2112 that are spaced apart along the thickness direction X. The second side wall 2112 is located on the side of the first side wall 2111 away from the battery cell 10. The first side wall 2111 includes a first side surface 21a. The plurality of reinforcing ribs 212 include a first reinforcing rib 212a connected to the first side wall 2111.

[0390] Exemplarily, among the plurality of reinforcing ribs 212 of the limiting beam 21, the reinforcing rib 212 directly connected to the first side wall 2111 is called the first reinforcing rib 212a. In the limiting beam 21, all the reinforcing ribs 212 may be the first reinforcing ribs 212a, or some of the reinforcing ribs 212 may be the first reinforcing ribs 212a.

[0391] Exemplarily, the reinforcing rib 212 and the outer wall 211 may be integrally formed. Alternatively, the reinforcing rib 212 may be independently formed from the outer wall 211. The reinforcing rib 212 may be inserted into the outer wall 211 and fixed to the outer wall 211 by welding, screwing or other means.

[0392] The expansion and deformation of the battery cell 10 during the cycling process will exert a force on the limiting beam 21, and the force is first applied to the first side wall 2111. The first reinforcing rib 212a is connected to the first side wall 2111, and it can transfer the force to other parts of the outer wall 211 and form a support for the first side wall 2111, thereby enhancing the anti-deformation ability of the first side wall 2111.

[0393] In some embodiments, the number of the reinforcing ribs 212 is 2 - 8.

[0394] In some embodiments, both ends of each reinforcing rib 212 are respectively connected to the first side wall 2111 and the second side wall 2112.

[0395] In some embodiments, the second side wall 2112 includes a second side surface 21b.

[0396] In some embodiments, at least one first reinforcing rib 212a is inclined with respect to the thickness direction X.

[0397] During the cycling process, the expansion and deformation of the battery cell 10 will exert a force on the first sidewall 2111, and the component force of this force along the thickness direction X is relatively large; the first reinforcing rib 212a inclined with respect to the thickness direction X can decompose the force, thereby reducing the risk of the first reinforcing rib 212a being crushed.

[0398] In some embodiments, the limiting beam 21 extends in a direction perpendicular to the thickness direction X. At least two first reinforcing ribs 212a are spaced apart in a direction perpendicular to both the extending direction Y of the limiting beam 21 and the thickness direction X, and are inclined in opposite directions with respect to the thickness direction X.

[0399] Exemplarily, at least two first reinforcing ribs 212a are arranged along the height direction Z of the battery cell 10.

[0400] Tilting at least two first reinforcing ribs 212a in opposite directions can further improve the structural strength and stiffness of the limiting beam 21. When the first sidewall 2111 is subjected to a force along the thickness direction X, the torque directions of the two first reinforcing ribs 212a are different, thereby reducing the risk of rotational deformation of the two first reinforcing ribs 212a.

[0401] In some embodiments, the included angle β between the first reinforcing rib 212a and the thickness direction X is 30° - 80°.

[0402] Setting the included angle β at 30° - 80° can balance the pressure and moment received by the first reinforcing rib 212a to a certain extent, reduce the risk of the first reinforcing rib 212a being crushed or undergoing rotational deformation, improve the structural strength and stiffness of the limiting beam 21, and provide effective restraint for the battery cell 10.

[0403] In some embodiments, the first sidewall 2111 includes a middle region 21111 and two edge regions 21112. In a direction parallel to the first side 21a and perpendicular to the extending direction Y of the limiting beam 21, the two edge regions 21112 extend from both ends of the middle region 21111, and the dimensions of the middle region 21111 and the edge regions 21112 are equal. At least one first reinforcing rib 212a is connected to the middle region 21111.

[0404] During the cycling of the battery cell 10, the center of the battery cell 10 expands significantly along its height direction Z. Since the middle region 21111 of the first side wall 2111 is opposite to the center of the battery cell 10, the force received by the middle region 21111 is generally greater than that received by the edge region 21112. Connecting at least one first reinforcing rib 212a to the middle region 21111 can provide support for the middle region 21111 to inhibit the expansion deformation of the battery cell 10 during cycling.

[0405] In some embodiments, at least two first reinforcing ribs 212a are directly connected to the middle region 21111.

[0406] In some embodiments, the number of first reinforcing ribs 212a directly connected to the middle region 21111 is greater than the number of first reinforcing ribs 212a directly connected to the edge region.

[0407] In some embodiments, all the first reinforcing ribs 212a are directly connected to the middle region 21111.

[0408] In some embodiments, the outer wall 211 includes a first side wall 2111 and a second side wall 2112 spaced apart along the thickness direction X. The second side wall 2112 is located on the side of the first side wall 2111 away from the plurality of battery cells 10. The first side wall 2111 includes a first side surface 21a. The second side wall 2112 includes a first section 21121 and a second section 21122. The first section 21121 is parallel to the first side wall 2111, and the second section 21122 extends from one end of the first section 21121 and inclines towards the first side wall 2111. At least one reinforcing rib 212 is connected to the connection between the first section 21121 and the second section 21122.

[0409] In the embodiments of the present application, the first section 21121 and the first side wall 2111 are not required to be absolutely parallel, and may also be approximately parallel as conventionally recognized in engineering.

[0410] Exemplarily, the first section 21121 includes a third side surface 21c, and the second section 21122 includes a second side surface 21b.

[0411] During the cycling of the battery cell 10, the battery cell 10 expands and applies a force to the first side wall 2111. A part of the force can be transmitted to the connection between the first section 21121 and the second section 21122 through the reinforcing rib 212, thereby dispersing the stress. Both the first section 21121 and the second section 21122 can support the first side wall 2111 through the reinforcing rib 212 to reduce the deformation of the first side wall 2111.

[0412] In some embodiments, the first reinforcing rib 212a is connected to the connection between the first section 21121 and the second section 21122.

[0413] Figure 13 A partial cross-sectional schematic diagram of the battery provided by some other embodiments of the present application.

[0414] In some embodiments, the outer wall 211 includes a first side wall 2111, a second side wall 2112, and a top wall 2113. The second side wall 2112 is located on a side of the first side wall 2111 away from the plurality of battery cells 10, and the top wall 2113 connects the first side wall 2111 and the second side wall 2112; the first side wall 2111 includes a first side surface 21a.

[0415] As an example, the top wall 2113 is located on one side of the accommodation cavity 213 along the height direction Z.

[0416] In some embodiments, the top wall 2113 includes a top surface, and the top surface connects the first side surface 21a and the second side surface 21b.

[0417] In some embodiments, the limiting beam 21 further includes a partition wall 214 connected to the top wall 2113. In the thickness direction X, the partition wall 214 is located between the first side wall 2111 and the second side wall 2112. At least one reinforcing rib 212 connects the first side wall 2111 and the partition wall 214, and at least one reinforcing rib 212 connects the second side wall 2112 and the partition wall 214.

[0418] By providing the partition wall 214 and the reinforcing ribs 212, a multi-chamber structure can be formed inside the limiting beam 21, which is beneficial to improving the overall stiffness of the limiting beam 21. During the cycling of the battery cell 10, the battery cell 10 expands and applies a force to the first side wall 2111. The partition wall 214 can transmit and disperse the force, thereby reducing the deformation of the first side wall 2111 and constraining the battery cell 10.

[0419] In some embodiments, the partition wall 214 can be integrally formed with the outer wall 211 or fixed to the outer wall 211 by welding.

[0420] In some embodiments, the partition wall 214 includes a third section 2141 and a fourth section 2142, and the fourth section 2142 extends from the upper end of the third section 2141 along the height direction Z and is inclined with respect to the third section 2141.

[0421] In some embodiments, the first section 21121 is parallel to the third section 2141, and the second section 21122 is parallel to the fourth section 2142.

[0422] In some embodiments, one end of a reinforcing rib 212 is connected to the connection point of the first section 21121 and the second section 21122, and the other end is connected to the connection point of the third section 2141 and the fourth section 2142.

[0423] In some embodiments, the reinforcing rib 212 connecting the second side wall 2112 and the partition wall 214 may be the second reinforcing rib 212b.

[0424] In some embodiments, at least one first reinforcing rib 212a is connected to the joint of the third section 2141 and the fourth section 2142.

[0425] In some embodiments, the outer wall 211 further includes a bottom wall 2114, and the bottom wall 2114 and the top wall 2113 are arranged along the height direction Z of the battery cell 10.

[0426] In some embodiments, the bottom wall 2114 is fixed to the carrier plate 24.

[0427] Figure 14 Schematic structural diagram of a battery provided in some other embodiments of the present application, Figure 15 is Figure 14 partial cross-sectional schematic diagram of the battery shown.

[0428] Referring to Figure 14 and Figure 15 , in some embodiments, the battery 2 further includes a constraint member 40, and the constraint member 40 connects adjacent limiting beams 21.

[0429] The constraint member 40 may be one or more.

[0430] The constraint member 40 can be connected to the limiting beam 21 by welding, clamping, fastener connection or other connection means.

[0431] The constraint member 40 is a strip structure, a linear structure, a beam structure or other structures. Exemplarily, the constraint member 40 extends along the thickness direction X of the battery cell 10.

[0432] During the cycling of the battery cell 10, the battery cell 10 expands and applies a force to the limiting beam 21. The constraint member 40 can provide a binding force to the limiting beam 21, thereby reducing the deformation of the limiting beam 21, restricting the expansion amount of the battery cell 10, improving the cycling performance of the battery cell 10, and reducing the risk of cracking of the box body 20.

[0433] In some embodiments, the constraint member 40 can apply a pre-tightening force to adjacent limiting beams 21.

[0434] In some embodiments, the constraint member 40 is a strip structure. The strip structure has low cost and small occupied space; by using the strip-structured constraint member 40, the space utilization rate inside the battery 2 can be improved, and the energy density of the battery 2 can be increased.

[0435] In some embodiments, the constraint member 40 includes a metal strip. Exemplarily, the constraint member 40 includes a steel strip.

[0436] In some embodiments, the restraint 40 is located on one side of the battery cell 10 in the height direction Z. The restraint 40 can limit the position of the battery cell 10 in the height direction Z.

[0437] In some embodiments, the restraint 40 is connected to the battery cell 10, which can increase the connection strength between the battery cell 10 and the box body 20, reduce the sway of the battery cell 10 relative to the box body 20 when the battery 2 is impacted, and improve the reliability and stability of the battery 2.

[0438] In some embodiments, one restraint 40 is connected to the battery cells 10 of at least one battery cell row 100. Optionally, one restraint 40 is connected to the battery cells 10 of two adjacent battery cell rows 100.

[0439] In some embodiments, the restraint 40 is adhesively bonded to the battery cell 10. By means of adhesion, a stable connection between the battery cell 10 and the restraint 40 can be quickly achieved, and the binding force of the restraint 40 on the battery cell 10 can be enhanced.

[0440] In some embodiments, an adhesive layer 50 is provided between the restraint 40 and the battery cell 10. Exemplarily, the adhesive layer 50 includes a structural member or double-sided tape.

[0441] In some embodiments, the restraint 40 is detachably connected to the limit beam 21. The detachable connection method can facilitate the later maintenance or replacement of the restraint 40.

[0442] The restraint 40 and the limit beam 21 can adopt, but are not limited to, bolt connection, snap connection or other detachable connection methods.

[0443] In some embodiments, the battery 2 further includes a fixing member 60, and the fixing member 60 connects the restraint 40 and the limit beam 21. At least a part of the fixing member 60 is embedded in the limit beam 21 and fixed to the limit beam 21.

[0444] The fixing member 60 can be integrally embedded in the limit beam 21 or only partially embedded in the limit beam 21. The fixing member 60 is fixed to the limit beam 21.

[0445] The fixing member 60 can be one or multiple.

[0446] The fixing member 60 can be fixed to the limit beam 21 by welding, clamping, riveting, bolt connection, adhesion or other means.

[0447] The fixing member 60 is embedded into the limiting beam 21, thereby enhancing the connection strength between the fixing member 60 and the limiting beam 21 and reducing the risk of connection failure between the fixing member 60 and the limiting beam 21. The restraining member 40 can be connected to the limiting beam 21 through the fixing member 60, and the connection between the fixing member 60 and the restraining member 40 is not restricted by the limiting beam 21. In this way, the connection mode between the fixing member 60 and the restraining member 40 can be flexibly selected as needed, improving the connection strength between the fixing member 60 and the restraining member 40.

[0448] In some embodiments, the limiting beam 21 has an accommodation cavity 213 inside, and the fixing member 60 is accommodated in the accommodation cavity 213. By providing the accommodation cavity 213, the fixing member 60 can be integrally embedded into the limiting beam 21, enhancing the connection strength between the fixing member 60 and the limiting beam 21.

[0449] Optionally, the limiting beam 21 is formed by splicing a plurality of sheet metal parts, and the fixing member 60 can be fixed to the sheet metal parts during the splicing process.

[0450] In some alternative embodiments, the limiting beam 21 is provided with an upper concave portion recessed from the top wall 2113, and the fixing member 60 can be inserted into the upper concave portion and fixed to the limiting beam 21.

[0451] In some embodiments, the restraining member 40 is fixed to the fixing member 60 through a fastener 80.

[0452] In some embodiments, the limiting beam 21 extends in a direction perpendicular to the thickness direction X. There are a plurality of restraining members 40, and the plurality of restraining members 40 are arranged at intervals along the extension direction Y of the limiting beam 21.

[0453] The plurality of restraining members 40 can increase the binding force received by the limiting beam 21, improve the uniformity of the force received by different regions of the limiting beam 21, reduce the deformation of the limiting beam 21 during the cycling process of the battery cell 10, and improve the cycling performance of the battery 2.

[0454] Figure 16 is Figure 4 an enlarged schematic view at the circular frame; Figure 17 is Figure 16 the structural schematic view of the first current collecting member shown; Figure 18 This is a connection schematic view of a battery cell and a first current collecting member provided in some embodiments of the present application.

[0455] Referring to Figure 4 and Figures 16 - 18 , in some embodiments, the battery 2 further includes a plurality of current collecting members 70, and the plurality of current collecting members 70 electrically connect the plurality of battery cells 10.

[0456] The plurality of current collecting members 70 can connect the plurality of battery cells 10 in series, parallel, or in a mixed connection.

[0457] Multiple current collecting components 70 may have the same structure or different structures.

[0458] In some embodiments, the multiple current collecting components 70 include at least one first current collecting component 70a. The first current collecting component 70a includes a first current collecting layer 71 and a second current collecting layer 72 that are stacked and connected. The first current collecting layer 71 is connected to at least two battery cells 10 arranged in the thickness direction X.

[0459] All of the multiple current collecting components 70 may be first current collecting components 70a, or some of them may be first current collecting components 70a.

[0460] The first current collecting layer 71 and the second current collecting layer 72 may be integrally formed. Alternatively, the first current collecting layer 71 and the second current collecting layer 72 may also be independently formed and connected by welding or other means.

[0461] The first current collecting component 70a has at least a double-layer structure, and both the first current collecting layer 71 and the second current collecting layer 72 of the first current collecting component 70a can conduct current. This can enable the first current collecting component 70a to have a relatively large current-carrying area, thereby reducing the heat generation of the first current collecting component 70a and improving the fast charging ability of the battery 2.

[0462] On the premise that the current-carrying area meets the requirements, setting the first current collecting component 70a as a double-layer structure can reduce the thickness of the first current collecting layer 71. During the cycling process, the battery cell 10 will expand, thereby stretching the first current collecting layer 71. The first current collecting layer 71 has a relatively small thickness and is easy to deform to adapt to the deformation of the battery cell 10, reducing the risk of the connection between the battery cell 10 and the first current collecting layer 71 being torn, and improving the reliability of the battery 2.

[0463] In some embodiments, the battery cell 10 includes an electrode terminal 13 disposed on the outer casing 12, and the electrode terminal 13 is electrically connected to the electrode assembly 11. The first current collecting layer 71 is connected to the electrode terminal 13 of the battery cell 10.

[0464] Optionally, the first current collecting layer 71 is welded to the electrode terminal 13.

[0465] In some embodiments, the portion of the first current collecting layer 71 that does not overlap with the second current collecting layer 72 is connected to the electrode terminal 13.

[0466] The second current collecting layer 72 can avoid the connection between the first current collecting layer 71 and the electrode terminal 13, so as to reduce the influence of the second current collecting layer 72 on the connection between the first current collecting layer 71 and the electrode terminal 13 when the battery cell expands, reduce the risk of the connection between the electrode terminal 13 and the first current collecting layer 71 being torn, and improve the reliability of the battery 2. In addition, when assembling the battery cell 10 and the first current collecting component 70a, the second current collecting layer 72 does not cover the area of the first current collecting layer 71 for connecting with the electrode terminal 13, which can reduce the assembly difficulty.

[0467] In some embodiments, the first current collecting layer 71 is welded to the electrode terminal 13 to form a welding mark, and the second current collecting layer 72 does not cover the welding mark.

[0468] In some embodiments, in the stacking direction of the first current collecting layer 71 and the second current collecting layer 72, the second current collecting layer 72 partially overlaps with the electrode terminal 13, which can shorten the conduction path between the second current collecting layer 72 and the electrode terminal 13, thereby reducing the resistance and heat generation.

[0469] In some embodiments, the first current collecting layer 71 and the second current collecting layer 72 are stacked along the height direction Z of the battery cell 10. In other words, the stacking direction of the first current collecting layer 71 and the second current collecting layer 72 is parallel to the height direction Z.

[0470] In some embodiments, the second current collecting layer 72 can be disposed on the side of the first current collecting layer 71 facing the battery cell 10, or can be disposed on the side of the first current collecting layer 71 facing away from the battery cell 10.

[0471] In some embodiments, the first current collecting component 70a includes at least one bending portion 73, and the bending portion 73 connects the first current collecting layer 71 and the second current collecting layer 72.

[0472] The bending portion 73 can be one or multiple.

[0473] The bending portion 73 can connect the first current collecting layer 71 and the second current collecting layer 72 and transmit current between the first current collecting layer 71 and the second current collecting layer 72, thereby improving the overcurrent capacity of the first current collecting component 70a.

[0474] In some embodiments, the first current collecting layer 71 includes a first current collecting portion 711, a second current collecting portion 712, and a first buffer portion 713 connecting the first current collecting portion 711 and the second current collecting portion 712. The first current collecting portion 711 and the second current collecting portion 712 are disposed along the thickness direction X and are connected to different battery cells 10.

[0475] In some embodiments, the bending portion 73 and the first buffer portion 713 are arranged to avoid each other. The bending portion 73 is not directly connected to the first buffer portion 713.

[0476] Exemplarily, the bent portion 73 extends from one end of the first current collecting layer 71 along the extending direction Y and bends away from the battery cell. The bent portion 73 does not cover the side surface of the first buffer portion 713 along the extending direction Y.

[0477] The first current collecting portion 711 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 current collecting portion 712 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.

[0478] During the cycling of the battery cell 10, the battery cell 10 expands and applies a tensile force to the first current collecting layer 71; the first buffer portion 713 can release stress through deformation, thereby reducing the force at the connection between the first current collecting portion 711 and the battery cell 10 and the force at the connection between the second current collecting portion 712 and the battery cell 10, and reducing the risk of connection failure between the first current collecting layer 71 and the battery cell 10. The bent portion 73 is not directly connected to the first buffer portion 713, thereby reducing the influence of the bent portion 73 on the deformation of the first buffer portion 713 and reducing the difficulty of deformation of the first buffer portion 713.

[0479] In some embodiments, the first current collecting portion 711 is located above the electrode terminal 13 of the battery cell 10, and the second current collecting portion 712 is located above the electrode terminal 13 of the battery cell 10.

[0480] In some embodiments, the first buffer portion 713 includes an arched structure.

[0481] In some embodiments, the first current collecting portion 711 is connected to the second current collecting layer 72 through at least one bent portion 73, and the second current collecting portion 712 is connected to the second current collecting layer 72 through at least one bent portion 73.

[0482] In some embodiments, the second current collecting layer 72 includes a first stacked portion 721, a second stacked portion 722, and a second buffer portion 723. The first stacked portion 721 is stacked with the first current collecting portion 711 and connected through at least one bent portion 73. The second stacked portion 722 is stacked with the second current collecting portion 712 and connected through at least one bent portion 73. The second buffer portion 723 connects the first stacked portion 721 and the second stacked portion 722. In the stacking direction of the first current collecting layer 71 and the second current collecting layer 72, the second buffer portion 723 and the first buffer portion 713 at least partially overlap.

[0483] During the cycling of the battery cell 10, the battery cell 10 expands and applies a tensile force to the first current collecting layer 71; both the first buffer portion 713 and the second buffer portion 723 can release stress through deformation, thereby reducing the risk of connection failure between the first current collecting layer 71 and the battery cell 10. The second buffer portion 723 overlaps at least partially with the first buffer portion 713, so that the deformation regions of the first buffer portion 713 and the second buffer portion 723 can be close, thereby reducing the risk of interference between the first buffer portion 713 and the second buffer portion 723 and other parts during deformation.

[0484] In some embodiments, the second buffer portion 723 and the first buffer portion 713 are disposed in a fitting manner. This embodiment of the present application can save space.

[0485] In some embodiments, the thickness of the first current collecting layer 71 is 1 mm - 2.5 mm. Optionally, the thickness of the first current collecting layer 71 is 1.2 mm - 1.8 mm. By way of example, the thickness of the first current collecting layer 71 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.

[0486] This embodiment of the present application selects the thickness of the first current collecting layer 71 according to the expansion pressure of the battery cell 10, which can balance the current-carrying capacity and the deformability of the first current collecting layer 71 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0487] In some embodiments, the thickness of the second current collecting layer 72 is 1 mm - 2.5 mm. Optionally, the thickness of the second current collecting layer 72 is 1.2 mm - 1.8 mm. By way of example, the thickness of the second current collecting layer 72 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.

[0488] The thickness of the second current collecting layer 72 can be selected according to the thickness of the first current collecting layer 71 and the current-carrying capacity of the battery for the first current collecting component. Exemplarily, when the thickness of the first current collecting layer 71 is relatively small, the second current collecting layer 72 can have a thickness greater than that of the first current collecting layer 71 to improve the current-carrying capacity of the first current collecting component.

[0489] In some embodiments, the volume energy density of the battery cell 10 is 390 Wh / L - 450 Wh / L, and the thickness of the first current collecting layer 71 is less than or equal to 2.5 mm.

[0490] The swelling of the battery cell 10 is related to its volumetric energy density. In this application, the thickness of the first current collecting layer 71 is designed according to the volumetric energy density of the battery cell 10, so as to balance the current-carrying capacity and deformability of the first current collecting layer 71 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0491] 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 current collecting layer 71 is less than or equal to 2.2 mm.

[0492] The swelling of the battery cell 10 is related to its volumetric energy density. For the battery 2 using the battery cell 10 with a high volumetric energy density, it is necessary to reduce the thickness of the first current collecting layer 71. In the embodiments of this application, the thickness of the first current collecting layer 71 is designed according to the volumetric energy density of the battery cell 10, so as to balance the current-carrying capacity and deformability of the first current collecting layer 71 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0493] In some embodiments, the electrode assembly 11 includes a negative electrode sheet 112. 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 includes a negative electrode active material, and the negative electrode active material includes a silicon-based material. The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% - 6%; the thickness of the first current collecting layer 71 is 1.2 mm - 2.2 mm, and the thickness of the second current collecting layer 72 is 1.2 mm - 2.2 mm.

[0494] As an example, the mass content of silicon element in the silicon-based material in the negative electrode active material is 1%, 2%, 3%, 4%, 5% or 6%. As an example, the thickness of the first current collecting layer 71 is 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 or 2.2 mm. As an example, the thickness of the second current collecting layer 72 is 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 or 2.2 mm.

[0495] By introducing the silicon-based material, the capacity of the negative electrode sheet 112 can be improved, and the energy density of the battery cell 10 can be increased. Introducing the silicon-based material will also increase the swelling of the negative electrode sheet 112 during cycling. By designing the thickness of the first current collecting layer 71 and the second current collecting layer 72 in combination with the content of silicon element, the risk of connection failure between the first current collecting layer 71 and the battery cell 10 caused by introducing the silicon-based material can be reduced, and the requirements for the current-carrying capacity of the first current collecting component 70a can be met.

[0496] In some embodiments, the first current collecting layer 71 includes a first current collecting portion 711, a second current collecting portion 712, and a first buffer portion 713 connecting the first current collecting portion 711 and the second current collecting portion 712. The first current collecting portion 711 and the second current collecting portion 712 are arranged along the thickness direction X and are connected to different battery cells 10. In the stacking direction of the first current collecting layer 71 and the second current collecting layer 72, the first buffer portion 713 protrudes from the first current collecting portion 711 and the second current collecting portion 712. The first current collecting layer 71 is provided with a recess 714 at a position corresponding to the first buffer portion 713.

[0497] By providing the recess 714, the strength of the first buffer portion 713 can be reduced, facilitating the deformation of the first buffer portion 713 when the battery cell 10 expands.

[0498] In some embodiments, the volume energy density of the battery cell 10 is 390 Wh / L - 450 Wh / L, and the depth H2 of the recess 714 is 1.2 mm - 2.5 mm.

[0499] The expansion of the battery cell 10 is related to its volume energy density. In this application, the depth of the recess 714 is designed according to the volume energy density of the battery cell 10, so as to balance the current-carrying capacity and deformability of the first buffer portion 713 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0500] In some embodiments, the volume energy density of the battery cell 10 is 450 Wh / L - 480 Wh / L, and the depth of the recess 714 is 1 mm - 2.2 mm.

[0501] The expansion of the battery cell 10 is related to its volume energy density. For the battery 2 using the battery cell 10 with a high volume energy density, it is necessary to reduce the difficulty of deformation of the first buffer portion 713. In the embodiments of this application, the depth of the recess 714 is designed according to the volume energy density of the battery cell 10, so as to balance the current-carrying capacity and deformability of the first buffer portion 713 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0502] Figure 19 A top view schematic diagram of the battery provided in other embodiments of this application; Figure 20 is Figure 19 An enlarged schematic diagram at the square box; Figure 21 is Figure 20 A structural schematic diagram of the second current collecting component in

[0503] Please refer to Figures 17 to 21, in some embodiments, the plurality of busbar components 70 further includes at least one second busbar component 70b, and the thickness of the second busbar component 70b is greater than the thickness of the first busbar layer 71 and greater than the thickness of the second busbar layer 72.

[0504] As an example, the second busbar component 70b has a single-layer structure, and the first busbar component 70a has a multi-layer structure.

[0505] In the battery 2, the expansion amounts of the battery cells 10 at different positions may vary. For the battery cells 10 with a small expansion amount, the second busbar component 70b with a single-layer structure can be used; compared with the first busbar component 70a, the second busbar component 70b has a simple structure, is easy to manufacture, and can save costs. The thickness of the second busbar component 70b is greater than the thickness of the first busbar layer 71 and the thickness of the second busbar layer 72, and its current-carrying capacity can meet the requirements.

[0506] In some embodiments, the sum of the thickness of the first busbar layer 71 and the thickness of the second busbar layer 72 is equal to the thickness of the second busbar component 70b. The embodiments of the present application can reduce the difference in the current-carrying capacity between the first busbar component 70a and the second busbar component 70b and improve the current consistency.

[0507] In some embodiments, the battery cells 10 adjacent to the limiting beam 21 are connected to the first busbar component 70a. During the charging process, the expansions of the plurality of battery cells 10 may be superimposed in the thickness direction X, which causes a large displacement of the battery cells 10 adjacent to the limiting beam 21; using the first busbar component 70a with a double-layer structure to connect the battery cells 10 close to the limiting beam 21 can reduce the risk of connection failure between the first busbar component 70a and the battery cells 10.

[0508] In some embodiments, the plurality of busbar components 70 further includes a third busbar component 70c, and the third busbar component 70c can connect two adjacent battery cells 10 along the extending direction.

[0509] In some embodiments, the charging time of the battery cell 10 from 10% state of charge (SOC) to 80% SOC is 5 minutes to 10.5 minutes. Exemplarily, the charging time of the battery cell 10 from 10% SOC to 80% SOC 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 the range composed of any two of the above values.

[0510] The battery cell 10 of the embodiments of the present application has the ability of fast charging and can save the charging time.

[0511] In some embodiments, the charging steps of the battery 2 or any battery cell 10 that makes up the battery 2 from 10% to 80% can be carried out as follows:

[0512] Charge from 10% SOC to 15% SOC at a constant current of 5.0C;

[0513] Charge from 15% SOC to 20% SOC at a constant current of 5.0C;

[0514] Charge from 20% SOC to 25% SOC at a constant current of 5.0C;

[0515] Charge from 25% SOC to 30% SOC at a constant current of 5.0C;

[0516] Charge from 30% SOC to 35% SOC at a constant current of 5.0C;

[0517] Charge from 35% SOC to 40% SOC at a constant current of 5.0C;

[0518] Charge from 40% SOC to 45% SOC at a constant current of 4.6C;

[0519] Charge from 45% SOC to 50% SOC at a constant current of 4.3C;

[0520] Charge from 50% SOC to 55% SOC at a constant current of 4.0C;

[0521] Charge from 55% SOC to 60% SOC at a constant current of 3.7C;

[0522] Charge from 60% SOC to 65% SOC at a constant current of 3.4C;

[0523] Charge from 65% SOC to 70% SOC at a constant current of 3.1C;

[0524] Charge from 70% SOC to 75% SOC at a constant current of 2.9C;

[0525] Charge from 75% SOC to 80% SOC at a constant current of 2.7C.

[0526] As an example, the above charging strategy is carried out in an environment of 30°C.

[0527] In some embodiments, the charging steps of the battery cell 10 from 0% SOC to 10% SOC can be carried out as follows: Charge from 0% SOC to 10% SOC at a constant current of 5.0C.

[0528] In some embodiments, the charging steps of the battery cell 10 from 80% SOC to 98% SOC can be carried out as follows:

[0529] Charge from 80% SOC to 85% SOC at a constant current of 1.8C;

[0530] Charge from 85% SOC to 90% SOC at a constant current of 1.3C;

[0531] Charge from 90% SOC to 95% SOC at a constant current of 0.7C;

[0532] Charge from 95% SOC to 98% SOC at a constant current of 0.33C.

[0533] In some embodiments, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be carried out as follows: Charge from 98% SOC to 100% SOC at a constant current of 0.01C, 0.05C, 0.1C or 0.3C. Optionally, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be carried out as follows: Charge from 98% SOC to 100% SOC at a constant current of 0.01C, 0.05C or 0.1C.

[0534] In some embodiments, during the process of charging the battery cell 10 from 10% SOC to 80% SOC, the charging current can be 2C - 6C, optionally 2.7C - 5C. During the charging process of the battery cell 10, the charging current can vary according to the SOC of the battery cell 10.

[0535] In some embodiments, the battery cell 10 is a lithium - ion battery cell. After cycling the battery cell 10 20 times according to the charging strategy and the discharging strategy, disassemble the negative electrode sheet of the battery cell 10, and observe and measure the lithium - plating area of the negative electrode sheet. The ratio of the area of the lithium - plating region to the total area of the negative electrode sheet is less than 2%.

[0536] As an example, the discharging strategy is to discharge at a constant current of 0.33C to 2.0V.

[0537] As an example, the charging strategy can be:

[0538] Charge from 0% SOC to 5% SOC at a constant current of 5.0C;

[0539] Charge from 5% SOC to 10% SOC at a constant current of 5.0C;

[0540] Charge from 10% SOC to 15% SOC at a constant current of 5.0C;

[0541] Charge from 15% SOC to 20% SOC at a constant current of 5.0C;

[0542] Charge from 20% SOC to 25% SOC at a constant current of 5.0C;

[0543] Charge from 25% SOC to 30% SOC at a constant current of 5.0C;

[0544] Charge from 30% SOC to 35% SOC at a constant current of 5.0C;

[0545] Charge from 35% SOC to 40% SOC at a constant current of 5.0C;

[0546] Charge from 40% SOC to 45% SOC at a constant current of 4.6C;

[0547] Charge from 45% SOC to 50% SOC at a constant current of 4.3C;

[0548] Charge from 50% SOC to 55% SOC at a constant current of 4.0C;

[0549] Charge from 55% SOC to 60% SOC at a constant current of 3.7C;

[0550] Charge from 60% SOC to 65% SOC at a constant current of 3.4C;

[0551] Charge from 65% SOC to 70% SOC at a constant current of 3.1C;

[0552] Charge from 70% SOC to 75% SOC at a constant current of 2.9C;

[0553] Charge from 75% SOC to 80% SOC at a constant current of 2.7C;

[0554] Charge from 80% SOC to 85% SOC at a constant current of 1.8C;

[0555] Charge from 85% SOC to 90% SOC at a constant current of 1.3C;

[0556] Charge from 90% SOC to 95% SOC at a constant current of 0.7C;

[0557] Charge from 95% SOC to 98% SOC at a constant current of 0.33C;

[0558] Charge from 98% SOC to 100% SOC at a constant current of 0.1C.

[0559] The battery cell 10 of the embodiment of the present application can charge from 10% SOC to 80% SOC within 10.5 minutes without lithium plating or with slight lithium plating, and has good fast charging ability. Exemplarily, when the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 0.05%, it can be considered that there is no lithium plating. When the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 2% and greater than or equal to 0.05%, it can be considered that there is slight lithium plating.

[0560] According to some embodiments of the present application, the present application further provides an electrical device, including the battery 2 of any one of the above embodiments, and the battery 2 is used to provide electrical energy for the electrical device. The electrical device may be any of the aforementioned devices or systems using the battery 2.

[0561] Referring to Figures 2 to 18 , an embodiment of the present application provides a battery 2, which includes a plurality of battery cells 10, a box body 20, a restraint member 40, and a plurality of bus bar components 70. The plurality of battery cells 10 are accommodated in the box body 20.

[0562] The battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12. The expansion pressure of the battery cell in the thickness direction X is 0.5 MPa - 2.4 MPa.

[0563] The electrode assembly 11 includes a positive electrode sheet 111, a negative electrode sheet 112, and a separator 113, and the separator 113 separates the positive electrode sheet 111 and the negative electrode sheet 112. Optionally, the positive electrode sheet 111, the negative electrode sheet 112, and the separator 113 are wound.

[0564] 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, and the negative electrode film layer 1122 includes a negative electrode active material. The porosity of the negative electrode sheet 112 is 27% - 40%. The compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 .

[0565] 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 disposed 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 disposed in the first negative electrode film layer 11221 and a second negative electrode active material disposed in the second negative electrode film layer 11222. 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. 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.

[0566] 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 compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3The porosity of the positive electrode sheet 111 is 25%-32%. 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. The positive electrode active material includes an olivine-structured lithium-containing phosphate or a modified material thereof. The volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm, 0.4µm≤Dv10≤0.7µm.

[0567] The box body 20 includes two limiting beams 21, and the two limiting beams 21 are arranged at intervals along the thickness direction X of the battery cell 10. A plurality of battery cells 10 are arranged in an array and constitute a plurality of battery cell columns 100, and the plurality of battery cell columns 100 are arranged along the extension direction Y of the limiting beams 21, and each battery cell column 100 includes at least two battery cells 10 arranged along the thickness direction X of the battery cell 10. A plurality of battery cells 10 are arranged between the two limiting beams 21.

[0568] The limiting beam 21 includes a first side surface 21 a facing the plurality of battery cells 10 , and the first side surface 21 a is configured such that, when subjected to a pressure of 1.7 MPa, a maximum displacement of the first side surface 21 a in the thickness direction X is less than or equal to 8 mm.

[0569] The box body 20 includes a frame 22 and a support beam 23. The frame 22 defines a storage space, and the limit beam 21 and multiple battery cells 10 are arranged in the storage space. The support beam 23 is arranged on the side of the limit beam 21 away from the multiple battery cells 10 and connects the frame 22 and the limit beam 21. The restraint member 40 connects adjacent limit beams 21 and is bonded to the battery cell 10.

[0570] The plurality of busbars 70 electrically connect the plurality of battery cells 10. The plurality of busbars 70 include at least one first busbar 70a including stacked and connected first and second busbar layers 71 and 72. The first busbar layer 71 connects at least two battery cells 10 arranged in the thickness direction X.

[0571] Example

[0572] The following examples more specifically describe the contents disclosed in the embodiments of the present application, and these examples are only for illustrative purposes, because it is obvious to those skilled in the art that various modifications and changes are made within the scope of the disclosure of the embodiments of the present application. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0573] Example 1

[0574] 1. Preparation of positive electrode sheet

[0575] The positive electrode plate includes a positive current collector and positive electrode film layers disposed on both sides of the positive current collector. The positive current collector is an aluminum foil with a thickness of 15 μm.

[0576] The positive electrode film layer is formed by uniformly coating the surface of the positive electrode conductive layer with a positive electrode slurry (the solvent is N-methylpyrrolidone NMP) and then drying and cold pressing. The positive electrode film layer includes a positive electrode active material, a binder polyvinylidene fluoride (PVDF), and a conductive agent acetylene black with a weight ratio of 97:2:1.

[0577] The positive electrode active material includes lithium iron phosphate and an ion-conducting layer. The ion-conducting layer coats the surface of the lithium iron phosphate. The ion-conducting 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.

[0578] The single-sided 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 .

[0579] 2. Preparation of the negative electrode plate

[0580] The negative electrode plate includes a negative current collector and negative electrode film layers disposed on both sides of the negative current collector. The negative current collector is a copper foil with a thickness of 6 μm.

[0581] The negative electrode film layer is formed by uniformly coating the surface of the negative electrode conductive layer with a negative electrode slurry (the solvent is deionized water) and then drying and cold pressing.

[0582] The single-sided 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 .

[0583] The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The second negative electrode film layer is located between the first negative electrode film layer and the negative current collector.

[0584] The first negative electrode film layer comprises graphite particles, conductive agent acetylene black, a first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-2-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose, with a mass ratio of 97.5:0.5:0.5:0.5:1. The mass content of lithium element in the first 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, and the carbon coating layer coats the surface of the artificial graphite with a mass content of 3.5%.

[0585] The second negative electrode film layer comprises graphite particles, conductive agent acetylene black, a second lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-2-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose, with a mass ratio of 96.5:0.5:0.5:1.5:1. The mass content of lithium element 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, and the carbon coating layer coats the surface of the artificial graphite with a mass content of 3.5%.

[0586] 3. Separator

[0587] The separator includes a base film, which is a 7-μm polyethylene film layer with a porosity of 42%.

[0588] 4. Preparation of electrolyte

[0589] The electrolyte includes organic solvents, lithium salts and additives.

[0590] The organic solvents include 60% chain carboxylic ester solvents (ethyl acetate) and 40% carbonate solvents (30% ethylene carbonate EC, and the rest is dimethyl carbonate). The mass content of each component in the organic solvents is calculated based on the mass of the organic solvents.

[0591] Based on the mass of the electrolyte, the mass content of the additives is 6.5%, which includes vinylene carbonate VC, fluoroethylene carbonate FEC, ethylene sulfite ES and lithium difluoro(oxalato)borate LiDFOB with a mass ratio of 5:0.5:0.5:0.5.

[0592] The lithium salt includes 1 mol / L lithium hexafluorophosphate LiPF6.

[0593] The conductivity of the electrolyte at room temperature is 16.4 mS / cm.

[0594] 5. Preparation of Battery Cell

[0595] Stack the above-mentioned positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator placed between the positive electrode sheet and the negative electrode sheet to play an isolation role, obtaining an electrode assembly. Place the electrode assembly in a housing, inject electrolyte after drying, and go through processes such as vacuum packaging, standing, formation, and shaping to obtain a battery cell.

[0596] 6. Preparation of Battery

[0597] Install the prepared multiple battery cells into a box and arrange them between two limiting beams, and then weld the busbar components and install the high-voltage and low-voltage wire harnesses to obtain a battery.

[0598] Among them, the limiting beam is made of aluminum alloy and may have a structure as shown in Figure 12 Two limiting beams are located on both sides of the multiple battery cells in the thickness direction. The thickness of the outer wall of the limiting beam is 2 mm, the thickness of the two reinforcing ribs of the limiting beam is 2 mm, and the included angle α between the first side and the second side of the limiting beam is 5°.

[0599] Example 2

[0600] Prepare battery cells and batteries using a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing are adjusted.

[0601] Example 3

[0602] Prepare battery cells and batteries using a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing are adjusted.

[0603] Example 4

[0604] Prepare battery cells and batteries using a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing are adjusted.

[0605] Example 5

[0606] Prepare battery cells and batteries using a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, the included angle α between the first side and the second side of the limiting beam, and the wall thickness of the outer wall of the limiting beam are adjusted.

[0607] Comparative Example 1

[0608] The battery cell and the battery were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing were adjusted.

[0609] Comparative Example 2

[0610] The battery cell and the battery were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing were adjusted.

[0611] Comparative Example 3

[0612] The battery cell and the battery were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, the included angle α between the first side and the second side of the limiting beam, and the wall thickness of the outer wall of the limiting beam were adjusted.

[0613] Performance Test

[0614] 1. Test the expansion pressure of the battery cell:

[0615] In an ambient temperature of 45°C, the battery cell prepared above was discharged at a constant current discharge rate of 1C to 2.0V;

[0616] The battery cell was clamped between two clamping plates. Among them, the two clamping plates were respectively located on both sides of the battery cell in the thickness direction and covered the large surface;

[0617] In an ambient temperature of 45°C, the battery cell was charged at a constant current charge rate of 0.8C to 3.8V, and the pressure exerted by the battery cell on the clamping plate was detected and recorded;

[0618] According to the above charging strategy and charging strategy, the battery cell was cycled for charge and discharge until the battery cell decayed to 70% SOH (the discharge capacity of the battery cell decayed to 70% of the nominal capacity of the battery cell), and the maximum pressure exerted by the battery cell on the clamping plate was recorded;

[0619] The expansion pressure Q of the battery cell in the thickness direction was calculated as: maximum pressure / large surface area.

[0620] 2. Test the maximum displacement E in the thickness direction of the first side of the limiting beam under a pressure of 1.7 MPa.

[0621] The box body was fixed to the fixture;

[0622] The pressure head of the pressure testing machine is pressed against the first side surface 21a of the limiting beam, wherein the pressing surface of the pressure head that presses against the first side surface 21a is the same as the large surface of the battery cell;

[0623] A constant force F is applied to the pressing head and the pressing head is moved along the thickness direction X of the battery cell 10 , and the maximum displacement E of the pressing head is recorded. Exemplarily, the area of the pressing surface is S, and F / S is 1.7 MPa.

[0624] It is explained here that the box used for detecting the maximum displacement E and the box used for installing the battery cells are the same type of box.

[0625] 3. Volume energy density test:

[0626] The first week discharge energy was tested according to the following steps: at 25°C, the prepared battery cell was charged to 3.8V at a constant current of 0.33C, and then discharged to 2.0V at a constant current of 0.33C, and the discharge energy A0 at this time was recorded in Wh.

[0627] Volume of battery cell: Use calipers to measure the length, width, and height of the battery cell (generally calculated based on the outer shell size of the battery cell, excluding the height of the electrode terminals and the insulating film outside the outer shell), and calculate the volume V0 of the battery cell in units of L.

[0628] The volume energy density of a battery cell is VED=A0 / V0, in units of Wh / L.

[0629] 4. Cycle performance test 1:

[0630] The prepared battery was discharged at an ambient temperature of 45° C., and the battery monomer was discharged to 2.0V at a constant current discharge rate of 1C;

[0631] The prepared battery was charged at an ambient temperature of 45° C., and the battery monomer was charged to 3.8V at a constant current charging rate of 0.8C;

[0632] The battery is charged and discharged cyclically according to the above charging strategy and charging strategy until the battery experiences a cycle dive or decays to 70% SOH (battery discharge capacity / battery nominal capacity = 70%).

[0633] 5. Cycle performance test 2:

[0634] The prepared battery was discharged at an ambient temperature of 30° C., and the battery monomer was discharged at 0.33C to 2.0V;

[0635] At an ambient temperature of 30°C, the following charging strategy is used for charging:

[0636] Charge from 0% SOC to 5% SOC at a constant current of 5.0C;

[0637] Charge from 5% SOC to 10% SOC at a constant current of 5.0C;

[0638] Charge from 10% SOC to 15% SOC at a constant current of 5.0C;

[0639] Charge from 15% SOC to 20% SOC at a constant current of 5.0C;

[0640] Charge from 20% SOC to 25% SOC at a constant current of 5.0C;

[0641] Charge from 25% SOC to 30% SOC at a constant current of 5.0C;

[0642] Charge from 30% SOC to 35% SOC at a constant current of 5.0C;

[0643] Charge from 35% SOC to 40% SOC at a constant current of 5.0C;

[0644] Charge from 40% SOC to 45% SOC at a constant current of 4.6C;

[0645] Charge from 45% SOC to 50% SOC at a constant current of 4.3C;

[0646] Charge from 50% SOC to 55% SOC at a constant current of 4.0C;

[0647] Charge from 55% SOC to 60% SOC at a constant current of 3.7C;

[0648] Charge from 60% SOC to 65% SOC at a constant current of 3.4C;

[0649] Charge from 65% SOC to 70% SOC at a constant current of 3.1C;

[0650] Charge from 70% SOC to 75% SOC at a constant current of 2.9C;

[0651] Charge from 75% SOC to 80% SOC at a constant current of 2.7C;

[0652] Charge from 80% SOC to 85% SOC at a constant current of 1.8C;

[0653] Charge from 85% SOC to 90% SOC at a constant current of 1.3C;

[0654] Charge from 90% SOC to 95% SOC at a constant current of 0.7C;

[0655] Charge from 95% SOC to 98% SOC at a constant current of 0.33C;

[0656] Charge from 98% SOC to 100% SOC at a constant current of 0.1C.

[0657] Perform cyclic charge and discharge on the battery according to the above charging strategies until cyclic voltage drop occurs or the battery degrades to 70% SOH.

[0658] It should be noted here that cyclic performance test one and cyclic performance test two are respectively performed on two batteries prepared by the same preparation method.

[0659] The test results of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1.

[0660]

[0661] Referring to Table 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing in Comparative Example 1 are relatively low. Although the battery cell has a relatively small expansion pressure and is not prone to cyclic voltage drop during cycling, the volume energy density of the battery cell is relatively low.

[0662] Referring to Examples 1-5 and Comparative Example 1, the embodiments of the present application can increase the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing, so that the volume energy density of the battery cell is greater than or equal to 390 Wh / L. Although the expansion pressure of the battery cell is not less than 0.5 MPa, combined with the limiting beam with high anti-deformation ability, the expansion of the battery cell can be effectively restricted to improve the cycling performance of the battery and the battery cell and reduce the risk of cyclic voltage drop of the battery.

[0663] Referring to Examples 1-5 and Comparative Example 2, by adjusting parameters such as the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing, the expansion pressure of the battery cell can be restricted to not exceed 2.4 MPa, and the volume energy density of the battery cell can reach 415 Wh / L. The limiting beam with high anti-deformation ability can effectively restrict the expansion of the battery cell to improve the cycling performance of the battery and the battery cell and reduce the risk of cyclic voltage drop of the battery.

[0664] Referring to Examples 1-5 and Comparative Example 3, by adjusting the included angle α and the wall thickness of the outer wall of the limiting beam, the anti-deformation ability of the limiting beam can be adjusted. By the included angle α, the wall thickness of the outer wall of the limiting beam or other parameters (such as the material of the limiting beam), the anti-deformation ability of the limiting beam can be increased to effectively restrict the expansion of the battery cell when the expansion pressure of the battery cell reaches 2.4 MPa, so as to improve the cycling performance of the battery and the battery cell and reduce the risk of cyclic voltage drop of the battery.

[0665] Referring to Table 1, in the embodiments of the present application, during the fast charging of the battery, the deformation of the battery cell can be restricted, the risk of battery cycle degradation can be reduced, and the cycle performance of the battery and the battery cell can be improved. The battery cell of the present application has the ability of fast charging, and the charging time for the battery cell to charge from 10% SOC to 80% SOC can be 5 minutes to 10.5 minutes.

[0666] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0667] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some 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, characterized in that, Comprising: A plurality of battery cells arranged along the thickness direction of the battery cell, the battery cell including a housing and an electrode assembly accommodated in the housing; And, A box body for accommodating the plurality of battery cells, the box body including at least two limiting beams, and the two adjacent limiting beams are respectively arranged on both sides of the plurality of battery cells along the thickness direction, Wherein, the expansion pressure of the battery cell in the thickness direction is 0.5 MPa - 2.4 MPa, the limiting beam includes a first side facing the plurality of battery cells, and the first side is configured such that: when subjected to a pressure of 1.7 MPa, the maximum displacement of the first side in the thickness direction is less than or equal to 8 mm.

2. The battery according to claim 1, characterized in that, The expansion pressure of the battery cell in the thickness direction is 1.5 MPa - 2.0 MPa.

3. The battery according to claim 1 or 2, characterized in that, The electrode assembly includes two first surfaces and two second surfaces, the two first surfaces are arranged opposite to each other along the thickness direction, the two second surfaces are arranged opposite to each other along a direction perpendicular to the thickness direction, and the second surfaces connect the two first surfaces; The area of the first surface is larger than the area of the second surface.

4. The battery according to claim 3, characterized in that, The first surface is parallel to the first side.

5. The battery according to claim 1, wherein, The electrode assembly includes a negative electrode sheet, the negative electrode sheet including a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

6. The battery according to claim 5, characterized in that, The single-sided coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 .

7. The battery according to claim 6, characterized in that, The single-sided coating weight of the negative electrode film layer is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 .

8. The battery according to claim 5, wherein, The compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 .

9. The battery according to claim 8, characterized in that, The compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.25 g / cm 3 to 1.36 g / cm 3 .

10. The battery according to claim 5, characterized in that, The porosity of the negative electrode sheet is 27% - 40%.

11. The battery according to claim 5, characterized in that, The negative electrode active material includes at least one of artificial graphite and natural graphite.

12. The battery according to claim 5, wherein, The negative electrode active material includes a silicon-based material, and the mass content of silicon element in the silicon-based material in the negative electrode active material is 0.3% to 10%.

13. The battery according to claim 12, wherein, The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% to 6%.

14. The battery according to claim 12, characterized in that, The silicon-based material includes at least one of silicon oxide compound and silicon-carbon composite.

15. The battery according to any one of claims 5-11, characterized in that, 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 provided 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 provided in the first negative electrode film layer and a second negative electrode active material provided 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 silicon-based material.

16. The battery according to claim 15, characterized in that, The ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer is 3:7 to 7:

3.

17. The battery according to claim 16, wherein, The ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer is 4:6 to 6:

4.

18. The battery according to claim 15, characterized in that, The thickness of the first negative electrode film layer is less than or equal to the thickness of the second negative electrode film layer.

19. The battery according to claim 15, characterized in that, 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.

20. The battery according to claim 15, characterized in that, The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm - 14.3 μm, and the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm.

21. The battery according to claim 20, wherein, The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm - 11.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 14.6 μm.

22. The battery according to claim 5, characterized in that, The specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g.

23. The battery according to claim 22, wherein, The specific surface area of the negative electrode active material is 0.6 m 2 / g - 1.2 m 2 / g.

24. The battery according to claim 1, characterized in that, The electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material is a lithium-containing phosphate.

25. The battery according to claim 24, wherein, The single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 .

26. The battery according to claim 25, wherein The single-sided coating weight of the positive electrode film layer is 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2 .

27. The battery according to claim 24, wherein, The compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 .

28. The battery according to claim 27, wherein, The compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.55 g / cm 3 - 2.70 g / cm 3 .

29. The battery according to claim 24, characterized in that, The porosity of the positive electrode sheet is 25% - 32%.

30. The battery according to claim 24, wherein, The thickness of the positive electrode sheet is 0.13 mm - 0.2 mm.

31. The battery according to claim 24, wherein, 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.

32. The battery according to claim 24, wherein, The volume average particle size of the positive electrode active material satisfies 1 µm ≤ Dv50 ≤ 2 µm, and 0.4 µm ≤ Dv10 ≤ 0.7 µm.

33. The battery according to claim 1, wherein, The battery cell includes an electrolyte accommodated in the housing.

34. The battery according to claim 33, wherein, The conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm.

35. The battery according to claim 33, characterized in that, The electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents.

36. The battery according to claim 35, characterized in that, The carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

37. The battery according to claim 35 or 36, characterized in that, The carboxylate includes R1-COO-R2, and R1 and R2 each independently include an alkyl group having 1 - 5 carbon atoms or a halogenated alkyl group having 1 - 5 carbon atoms.

38. The battery according to claim 33, wherein, The electrolyte includes a lithium salt, the lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L.

39. The battery according to claim 33, characterized in that, The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

40. The battery according to claim 1, characterized in that, The electrode assembly includes a negative electrode sheet; the size of the electrode assembly in the thickness direction is T, the thickness of the negative electrode sheet is T1, and the number of layers of the negative electrode sheet stacked in the thickness direction is N; T, T1, and N satisfy: 0.3 ≤ (N×T1) / T ≤ 0.

5.

41. The battery according to claim 1, wherein, The distance between two adjacent limiting beams in the thickness direction is D1; A plurality of battery cell columns are provided between the adjacent limiting beams, the plurality of battery cell columns are arranged in a direction perpendicular to the thickness direction, and each battery cell column includes at least two battery cells arranged in the thickness direction; The total size of the electrode assemblies of the battery cells in the battery cell column in the thickness direction is D2; 85% ≤ D2 / D1 ≤ 92%.

42. The battery according to claim 1, characterized in that, The limiting beam includes a second side surface, and the second side surface is located on the side of the limiting beam away from the plurality of battery cells and is inclined towards the first side surface.

43. The battery according to claim 42, characterized in that, The included angle α between the first side surface and the second side surface is 1° - 25°.

44. The battery according to claim 42 or 43, characterized in that, The volume energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the included angle α between the first side surface and the second side surface is 5° - 20°.

45. The battery according to claim 42 or 43, characterized in that, The volume energy density of the battery cell is 450 Wh / L-480 Wh / L, and the angle α between the first side surface and the second side surface is 8°-25°.

46. The battery according to claim 42, wherein The electrode assembly comprises a negative electrode sheet, the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises at least one of a silicon-oxygen compound and a silicon-carbon composite; An included angle α between the first side surface and the second side surface is 8°-25°.

47. The battery according to claim 42, wherein The limiting beam comprises a third side surface, the third side surface is located at a side of the limiting beam away from the battery cell and is parallel to the first side surface, and the third side surface is connected to the second side surface.

48. The battery according to claim 1, characterized in that, The box body comprises a frame body and a support beam, the frame body defines a receiving space, the limiting beam and the plurality of battery cells are arranged in the receiving space; The support beam is arranged on a side of the limiting beam away from the plurality of battery cells and connects the frame and the limiting beam.

49. The battery according to claim 48, characterized in that, The limiting beam extends in a direction perpendicular to the thickness direction; The box body includes a plurality of support beams arranged at intervals along the extending direction of the limiting beam.

50. The battery according to claim 48 or 49, characterized in that, The limiting beam further includes a second side surface and a third side surface, the third side surface is located at a side of the limiting beam away from the battery cell and is parallel to the first side surface, and the second side surface is connected to one end of the third side surface and is inclined toward the first side surface; The support beam is connected to the third side surface.

51. The battery according to claim 1, characterized in that, The limiting beam comprises an outer wall and a plurality of reinforcing ribs, the outer wall encloses a receiving cavity, and the plurality of reinforcing ribs are arranged in the receiving cavity and connected to the outer wall; The outer wall includes the first side.

52. The battery according to claim 51, wherein, The electrode assembly comprises a negative electrode sheet, the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises a silicon-based material; The mass content of silicon element in the silicon-based material in the negative electrode active material is 1%-6%; the thickness of the outer wall is 2mm-7mm, and the thickness of the reinforcing rib is 2mm-7mm.

53. The battery according to claim 51 or 52, characterized in that, The outer wall includes a first side wall and a second side wall spaced apart along the thickness direction, the second side wall is located on a side of the first side wall away from the battery cell, and the first side wall includes the first side surface; The plurality of reinforcing ribs include a first reinforcing rib connected to the first side wall.

54. The battery according to claim 53, characterized in that, At least one of the first reinforcing ribs is inclined relative to the thickness direction.

55. The battery according to claim 54, characterized in that, The limiting beam extends in a direction perpendicular to the thickness direction; At least two of the first reinforcing ribs are arranged at intervals along a direction perpendicular to both the extension direction of the limiting beam and the thickness direction, and are inclined in opposite directions relative to the thickness direction.

56. The battery according to claim 54, characterized in that, The angle between the first reinforcing rib and the thickness direction is 30°-80°.

57. The battery according to claim 53, characterized in that, The first side wall includes a middle area and two edge areas, and the two edge areas extend from two ends of the middle area in a direction parallel to the first side surface and perpendicular to the extension direction of the limiting beam, and the middle area and the edge area have the same size; At least one of the first reinforcing ribs is connected to the middle region.

58. The battery according to claim 53, characterized in that, The outer wall includes a first side wall and a second side wall spaced apart in the thickness direction, the second side wall is located on a side of the first side wall away from the plurality of battery cells, and the first side wall includes the first side surface; The second side wall includes a first section and a second section, the first section is parallel to the first side wall, and the second section extends from one end of the first section and inclines toward the first side wall; At least one of the reinforcing ribs is connected to a connection portion between the first section and the second section.

59. The battery according to claim 51, wherein The outer wall includes a first side wall, a second side wall, and a top wall, the second side wall is located on a side of the first side wall away from the plurality of battery cells, and the top wall connects the first side wall and the second side wall; the first side wall includes the first side surface; The limiting beam further includes a partition wall connected to the top wall, and in the thickness direction, the partition wall is located between the first side wall and the second side wall; At least one of the reinforcing ribs connects the first side wall and the partition wall, and at least one of the reinforcing ribs connects the second side wall and the partition wall.

60. The battery according to claim 51, wherein, The limiting beam is an integrally formed structure.

61. The battery according to claim 1, wherein The battery further includes an insulating member disposed between the limiting beam and the outer shell.

62. The battery according to claim 1, characterized in that, The battery further includes a constraining member, and the constraining member connects adjacent limiting beams.

63. The battery according to claim 62, characterized in that, The constraining member is connected to the battery cell.

64. The battery according to claim 63, wherein, The constraining member is adhered to the battery cell.

65. The battery according to claim 62, characterized in that, The constraining member is detachably connected to the limiting beam.

66. The battery according to claim 62, wherein, The battery further includes a fixing member, the fixing member connects the constraining member and the limiting beam, and at least a part of the fixing member is embedded in the limiting beam and fixed to the limiting beam.

67. The battery according to claim 66, wherein, The limiting beam has a receiving cavity inside, and the fixing member is received in the receiving cavity.

68. The battery according to claim 62, wherein The limiting beam extends in a direction perpendicular to the thickness direction; There are a plurality of the constraining members, and the plurality of constraining members are spaced apart along the extending direction of the limiting beam.

69. The battery according to claim 1, characterized in that, The battery further includes a plurality of current collecting components, and the plurality of current collecting components electrically connect the plurality of battery cells; The plurality of current collecting components include at least one first current collecting component, the first current collecting component includes a first current collecting layer and a second current collecting layer stacked and connected, and the first current collecting layer connects at least two of the battery cells arranged in the thickness direction.

70. The battery according to claim 69, wherein, The battery cell includes an electrode terminal disposed on the outer shell, and the electrode terminal is electrically connected to the electrode assembly; A portion of the first current collecting layer that does not overlap with the second current collecting layer is connected to the electrode terminal.

71. The battery according to claim 69 or 70, characterized in that, The first current collecting component includes at least one bending portion, and the bending portion connects the first current collecting layer and the second current collecting layer.

72. The battery according to claim 71, characterized in that, The first current collecting layer includes a first current collecting portion, a second current collecting portion, and a first buffer portion connecting the first current collecting portion and the second current collecting portion, and the first current collecting portion and the second current collecting portion are arranged in the thickness direction and connected to different battery cells; The bending portion and the first buffer portion are arranged to avoid each other.

73. The battery according to claim 72, characterized in that, The second current collecting layer includes a first stacked portion, a second stacked portion, and a second buffer portion. The first stacked portion is stacked with the first current collecting portion and connected through at least one of the bent portions. The second stacked portion is stacked with the second current collecting portion and connected through at least one of the bent portions. The second buffer portion connects the first stacked portion and the second stacked portion; In the stacking direction of the first current collecting layer and the second current collecting layer, at least a part of the second buffer portion overlaps with the first buffer portion.

74. The battery according to claim 73, wherein, The second buffer portion and the first buffer portion are disposed in a fitting manner.

75. The battery according to claim 69, wherein, The plurality of current collecting components further includes at least one second current collecting component, the thickness of the second current collecting component is greater than the thickness of the first current collecting layer, and the thickness of the second current collecting component is greater than the thickness of the second current collecting layer.

76. The battery according to claim 75, characterized in that, The sum of the thickness of the first current collecting layer and the thickness of the second current collecting layer is equal to the thickness of the second current collecting component.

77. The battery according to claim 69, characterized in that, The battery cell adjacent to the limiting beam is connected to the first current collecting component.

78. The battery according to claim 69, characterized in that, The thickness of the first current collecting layer is 1 mm - 2.5 mm; and / or, the thickness of the second current collecting layer is 1 mm - 2.5 mm.

79. The battery according to claim 69, wherein, The volume energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the thickness of the first current collecting layer is less than or equal to 2.5 mm; or, The volume energy density of the battery cell is 450 Wh / L - 480 Wh / L, and the thickness of the first current collecting layer is less than or equal to 2.2 mm.

80. The battery according to claim 69, wherein, The electrode assembly includes a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material; The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% - 6%; the thickness of the first current collecting layer is 1.2 mm - 2.2 mm, and the thickness of the second current collecting layer is 1.2 mm - 2.2 mm.

81. The battery according to claim 69, characterized in that, The first current collecting layer includes a first current collecting portion, a second current collecting portion, and a first buffer portion connecting the first current collecting portion and the second current collecting portion. The first current collecting portion and the second current collecting portion are disposed along 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 portion protrudes from the first current collecting portion and the second current collecting portion; The first current collecting layer is provided with a concave portion at a position corresponding to the first buffer portion.

82. The battery according to claim 81, wherein The volume energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the depth of the concave portion is 1.2 mm - 2.5 mm; or, The volume energy density of the battery cell is 450 Wh / L - 480 Wh / L, and the depth of the concave portion is 1 mm - 2.2 mm.

83. The battery according to claim 1, characterized in that, The charging time of the battery cell from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes.

84. An electrical device, characterized in that, Including the battery according to any one of claims 1 - 83, the battery is used to provide electric energy.

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