Battery and electric device

Abstract

A battery (2) and an electric device. The battery (2) comprises multiple battery cells (10) and a case (20). The multiple battery cells (10) are arranged along the thickness direction of the battery cells (10), and each battery cell (10) comprises a casing (12) and an electrode assembly (11) accommodated in the casing (12). The case (20) is used for accommodating the multiple battery cells (10). The case (20) comprises at least two limiting beams (21), and two adjacent limiting beams (21) are respectively arranged on two sides of the multiple battery cells (10) along the thickness direction. The swelling pressure of the battery cells (10) in the thickness direction ranges from 0.5 MPa to 2.4 MPa. Each limiting beam (21) comprises a first side surface (21a) facing the multiple battery cells (10), and the first side surface (21a) is configured so that under a pressure of 1.7 MPa, the maximum displacement of the first side surface (21a) in the thickness direction is less than or equal to 8 mm.

Description

Battery and power consuming device TECHNICAL FIELD

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

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

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

[0004] SUMMARY

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

[0006] In a first aspect, an embodiment of the present application provides a battery, which includes a plurality of battery monomers and a box body. The plurality of battery monomers are arranged along the thickness direction of the battery monomers, and the battery monomers include a shell and an electrode assembly contained in the shell. The box body is used to contain the plurality of battery monomers, and the box body includes at least two limiting beams, and the adjacent two limiting beams are respectively arranged on both sides of the plurality of battery monomers along the thickness direction. The expansion pressure of the battery monomers in the thickness direction is 0.5 MPa-2.4 MPa. The limiting beam includes a first side surface facing the plurality of battery monomers, and the first side surface is configured to have a maximum displacement in the thickness direction less than or equal to 8 mm under a pressure of 1.7 MPa.

[0007] The expansion pressure of the battery monomers is related to the density of the electrode assembly. The limiting beam of the embodiment of the present application has high strength, so that the battery monomers can have an expansion pressure greater than or equal to 0.5 MPa in the thickness direction, thereby improving the density of the electrode assembly and increasing the energy density of the battery monomers. The expansion pressure of the battery monomers in the thickness direction is less than or equal to 2.4 MPa, and the limiting beam has high deformation resistance. Therefore, the limiting beam can effectively constrain the battery monomers in the thickness direction to reduce the deformation of the electrode assembly in the cycle process, reduce the risk of crease deformation of the separator of the electrode assembly and the risk of local increase in the distance between the positive plate and the negative plate, reduce polarization, and improve the cycle performance of the battery monomers. The present application controls the expansion pressure of the battery monomers within a reasonable range and designs the limiting beam accordingly, which can reduce the deformation of the battery monomers and the limiting beam, reduce the risk of cracking of the box body, and improve the cycle performance of the battery monomers.

[0008] In some embodiments, the expansion pressure of the battery cell in the thickness direction is 1.5MPa-2.0MPa. This reduces the deformation of the limiting beam, lowers the risk of casing cracking, and improves the cycle performance of the battery cell. Limiting the expansion pressure of the battery cell to 1.5MPa-2.0MPa also reduces the strength requirements of the limiting beam, thereby reducing costs.

[0009] In some embodiments, the electrode assembly includes two first surfaces and two second surfaces. The two first surfaces are disposed opposite each other along the thickness direction, and the two second surfaces are disposed opposite each other along a direction perpendicular to the thickness direction. The second surfaces connect the two first surfaces. The area of ​​the first surface is larger than the area of ​​the second surface. By aligning the larger first surface with the first side surface along the thickness direction, the stress-bearing area of ​​the limiting beam can be increased, thereby reducing the deformation of the limiting beam when the battery assembly expands.

[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 local deformation of the limiting beam, improve the consistency of the force on the electrode assembly, and improve the cycle performance of the battery cell.

[0011] In some embodiments, the electrode assembly includes a negative electrode sheet, the negative electrode sheet including 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 including a negative electrode active material.

[0012] In some embodiments, the single-sided coating weight of the negative electrode film is 90 mg / 1540 mm. 2 Up to 170mg / 1540mm 2 110mg / 1540mm is available as an option. 2 Up to 150mg / 1540mm 2 The single-sided coating weight of the negative electrode film is related to the expansion of the negative electrode film. Limiting the single-sided coating weight of the negative electrode film 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 at 100% SOC of the battery cell is 1.15 g / cm³. 3 Up to 1.36 g / cm 3 The option is 1.25g / cm³. 3 Up to 1.36 g / cm 3 The compaction density of the negative electrode film is related to the expansion of the battery cell at 100% charge. Limiting the compaction density of the negative electrode film to 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 is greater than or equal to 27%, which can provide space for impurities generated by side reactions of the negative electrode sheet, slow down the expansion of the negative electrode sheet, reduce the expansion pressure of the battery 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 negative electrode sheet is less than or equal to 40%, which can balance 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 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 in the negative electrode active material is 0.3-10%, which can be 1-6%. The introduction of the silicon-based material into the negative electrode sheet can not only improve the capacity and energy density of the battery cell, but also increase the expansion of the negative electrode sheet. Therefore, limiting the mass content of silicon in the negative electrode active material to 0.3-10% can balance the energy density and expansion of the battery cell to a certain extent, reduce the deformation of the battery cell and the limiting beam, and improve the cycle performance of the battery cell.

[0017] In some embodiments, the silicon-based material includes at least one of a silicon oxide compound and a silicon-carbon composite.

[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 arranged between the first negative electrode film layer and the negative electrode current collector. The negative electrode active material includes a first negative electrode active material arranged in the first negative electrode film layer and a second negative electrode active material arranged in the second negative electrode film layer, the first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and a silicon-based material. The first negative electrode film layer and the second negative electrode film layer can be differentially arranged, thereby balancing the expansion and capacity of the negative electrode film layer to a certain extent; double-layer coating can construct the porosity difference of the negative electrode film layer, reduce the ion transmission tortuosity, reduce the side reaction, and improve the fast charging performance of the battery cell.

[0019] In some embodiments, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer is 3:7-7:3, which can be 4:6-6:4. By adjusting the thickness ratio of the first negative electrode film layer to the second negative electrode film layer, the gradient porosity difference between the upper and lower layers can be further increased, the lithium ion transmission tortuosity can be reduced, and the fast charging capacity 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 capacity 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] The difference in particle size between the first and second negative electrode active materials can improve the fast charging performance of the battery cell. During fast charging, the overpotential of the first negative electrode film is usually high, and the bottleneck of fast charging mainly lies in the first negative electrode film. However, in the embodiments of this application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transport path of ions, improve fast charging performance, and improve the problem of ion deposition on the surface of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film. During charging, the pores can absorb expansion, reduce the expansion of the negative electrode film, 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, 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, optionally 9.5 μm-14.6 μm.

[0024] Setting the volume average particle size Dv50 of the first negative electrode active material within the aforementioned range can, on the one hand, shorten the solid-phase transport path of lithium ions and improve fast charging performance; on the other hand, the material is less prone to agglomeration during preparation, thus improving its stability; furthermore, the first negative electrode active material within the aforementioned volume average particle size range can work in conjunction with the second negative electrode active material, which is beneficial for constructing a gradient porosity difference between the first and second negative electrode films, 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 between 9.5 μm and 18.5 μm, which can make the porosity of the second negative electrode film more abundant, which is beneficial for improving the fast charging capability of the battery cell and reducing the expansion of the negative electrode film during charging.

[0025] In some embodiments, the specific surface area of ​​the negative electrode active material is 0.5 m². 2 / g-3m 2 / g, optional 0.6m 2 / g-1.2m 2 / g. The specific surface area of ​​the negative electrode active material is limited to greater than or equal to 0.5m². 2 / g can improve the fast charging capability of individual battery cells; the specific surface area of ​​the negative electrode active material is limited to less than or equal to 3m². 2 / g can reduce side reactions of individual battery cells during storage and reduce expansion pressure.

[0026] In some embodiments, the electrode assembly comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material is a lithium-containing phosphate. The lithium-containing phosphate has high cycle stability, and the use of the lithium-containing phosphate as the positive electrode active material can improve the cycle decay 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 ; and can be 240 mg / 1540 mm 2 -330 mg / 1540 mm 2 . Setting the single-sided coating weight of the positive electrode film layer in 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 the 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 -2.80 g / cm 3 ; and can be 2.55 g / cm 3 -2.70 g / cm 3 . When the compaction density of the positive electrode film layer is in the above range, it is beneficial to improve the energy density of the battery cell; and since the positive electrode active material in the positive electrode film layer is packed more tightly, the contact resistance between particles is smaller, 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%. When the porosity of the positive electrode sheet is greater than or equal to 25%, it can provide space for impurities generated by side reactions of the positive electrode sheet, reduce the swelling 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. When the porosity of the positive electrode sheet is less than or equal to 32%, the energy density of the battery cell can be taken into account.

[0030] In some embodiments, the thickness of the positive electrode sheet is 0.13 mm-0.2 mm. The use of a positive electrode sheet with a smaller thickness can shorten the ion migration path, improve 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 electrode 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 electrode 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 electrode current collector, reduce the temperature rise of the positive electrode sheet, and improve the rapid charging performance of the battery cell. Limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be less than or equal to 0.3 can reduce the loss of capacity of the positive electrode sheet. The embodiments of the present application limit the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be 0.05-0.3, which can balance the rapid charging performance and energy density of the battery cell to a certain extent.

[0032] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1 μm≤Dv50≤2 μm, 0.4 μm≤Dv10≤0.7 μm. The particle size of the positive electrode active material is relatively small, the lithium ion deintercalation path in the positive electrode active material is shorter, and the heat generation is less. Moreover, the particle size of the positive electrode active material is not too small, which can reduce agglomeration during processing and preparation, and the performance of the positive electrode active material is stable.

[0033] In some embodiments, the battery cell includes an electrolyte contained in the shell.

[0034] In some embodiments, the electrolyte has an electrical conductivity of 15 mS / cm to 20 mS / cm at room temperature. When the electrical conductivity of the electrolyte is in the above range, the ion migration rate in the electrolyte is high, thereby further reducing the internal resistance of the battery cell, reducing heat generation, and improving the rapid 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 a carbonate-based solvent and a carboxylate-based solvent. The combination of the organic solvent can improve the electrical conductivity and reduce the viscosity of the electrolyte, thereby improving the rapid charging performance of the battery.

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

[0037] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 each independently includes an alkyl group having 1-5 carbon atoms or a halogenated alkyl group having 1-5 carbon atoms. The chain carboxylate-based solvent has high electrical conductivity, which is conducive to improving the rapid charging performance of the battery cell.

[0038] In some embodiments, the electrolyte comprises a lithium salt, the lithium salt comprises lithium bisfluorosulfonylimide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bisfluorosulfonylimide LiFSI is 0.2-0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5-1.0 mol / L.

[0039] In some embodiments, the density p of the electrolyte at room temperature satisfies 1.05 g / mL≤p≤1.35 g / mL. When the density p of the electrolyte is in the above range, the migration rate of lithium ions in the electrolyte is higher, which can further reduce the internal resistance of the battery cell, thereby reducing the heat generation and improving the rapid charging performance of the battery cell.

[0040] In some embodiments, the electrode assembly comprises a negative electrode sheet; the electrode assembly has a size T in the thickness direction, the negative electrode sheet has a thickness T1, and the negative electrode sheet has N layers stacked in the thickness direction. T, T1 and N satisfy 0.3≤(N×T1) / T≤0.5. During the cycle of the battery cell, the thickness of the negative electrode sheet increases due to the irreversible side reaction, thereby causing the expansion of the battery cell. 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 the two adjacent limiting beams in the thickness direction is D1. A plurality of battery cell columns are arranged 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 comprises at least two battery cells arranged in the thickness direction. The total size of the electrode assemblies of the battery cells of the battery cell column in the thickness direction is D2; 85%≤D2 / D1≤92%.

[0042] D2 / D1 is related to the expansion pressure of 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 cracking of the box body. Limiting D2 / D1 to be greater than or equal to 85% can improve the space utilization in the thickness direction and improve 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 comprises a second side surface, the second side surface is located on the side of the limiting beam away from the plurality of battery cells, and is inclinedly arranged towards the first side surface.

[0044] When the limiting beam is subjected to force due to expansion of the battery cell during the battery cell cycle, the second side can decompose the force in a tilt manner, thereby improving the deformation resistance of the limiting beam and reducing the deformation or displacement of the first side; the first side can provide stronger constraint to the battery cell to reduce the expansion deformation of the battery cell and improve the cycle performance of the battery cell. Compared with the scheme of improving the deformation resistance of the limiting beam by increasing the overall size of the limiting beam, the scheme of improving the deformation resistance of the limiting beam by using the tilt second side can reduce the weight of the limiting beam and improve the energy density of the battery.

[0045] In some embodiments, the included angle a between the first side and the second side is 1°-25°. Setting the included angle a to be greater than or equal to 1° can make the limiting beam have higher structural strength and rigidity and reduce the deformation resistance of the limiting beam. Setting the included angle a 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 of the limiting beam in the thickness direction.

[0046] In some embodiments, the volumetric energy density of the battery cell is 390Wh / L-450Wh / L, and the included angle a between the first side and the second side is 5°-20°. The expansion of the battery cell is related to its volumetric energy density. The present application designs the included angle a according to the volumetric energy density of the battery cell, thereby to some extent taking into account the requirements of the battery on the expansion pressure and the requirements on the energy density.

[0047] In some embodiments, the volumetric energy density of the battery cell is 450Wh / L-480Wh / L, and the included angle a 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 a can make the limiting beam provide more constraint force to the battery cell, thereby improving the cycle 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 arranged 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 a between the first side and the second side is 8°-25°.

[0049] By introducing the silicon oxide compound or the silicon-carbon composite, the capacity of the negative electrode sheet can be improved, and the energy density of the battery cell can be improved. The introduction of the silicon oxide compound and the silicon-carbon composite also increases the expansion of the negative electrode sheet during the cycle process. Setting the included angle a to be 8°-25° can improve the deformation resistance of the limiting beam, thereby providing constraint to the expansion of the battery cell and reducing the risk of cycle attenuation of the battery cell caused by the introduction of the silicon oxide compound or the silicon-carbon composite.

[0050] In some embodiments, the limiting beam comprises a third side surface, which is located on a side of the limiting beam away from the battery cell and parallel to the first side surface, and 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, and the space utilization rate can be improved. Through the combination of the third side surface and the second side surface, the limiting beam can also form a cross section similar to a trapezoid, so as to improve the structural strength and rigidity of the limiting beam and reduce the deformation of the limiting beam.

[0051] In some embodiments, the box body comprises a frame and a supporting beam, the frame defines a containing space, the limiting beam and the plurality of battery cells are arranged in the containing space. The supporting beam is arranged on a side of the limiting beam away from the plurality of battery cells and is connected to the frame and the limiting beam.

[0052] In the cycle process of the battery, the limiting beam is used to resist the expansion force of the battery cell in the cycle process, and the frame can support the limiting beam through the supporting beam, thereby providing effective support for the limiting beam, reducing the deformation of the limiting beam, and then providing constraint to the battery cell, reducing the expansion of the battery cell, and improving the cycle life of the battery cell.

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

[0054] In some embodiments, the limiting beam further comprises a second side surface and a third side surface, the third side surface is located on a side of the limiting beam away from the battery cell and parallel to the first side surface, and the second side surface is connected to one end of the third side surface and inclined toward the first side surface. The supporting beam is connected to the third side surface. The third side surface is perpendicular to the thickness direction, and connecting the supporting beam to the third side surface can enable the supporting 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 comprises an outer wall and a plurality of reinforcing ribs, the outer wall encloses a containing cavity, and the plurality of reinforcing ribs are arranged in the containing cavity and connected to the outer wall. The outer wall comprises a first side surface. The containing cavity can not only provide a deformation space for energy absorption of the limiting beam, but also reduce the overall weight of the limiting beam, which is conducive to improving the energy density of the battery. The reinforcing ribs can improve the structural strength and rigidity of the limiting beam and improve the anti-deformation capability of the limiting beam.

[0056] In some embodiments, the electrode assembly comprises a negative electrode sheet, the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged 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 in the silicon-based material in the negative electrode active material is 1% to 6%, the thickness of the outer wall is 2 mm to 7 mm, and the thickness of the reinforcing rib is 2 mm to 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 improved. By introducing the silicon-based material, the expansion of the negative electrode sheet during the cycle process is also increased. By designing the thickness of the outer wall and the thickness of the reinforcing rib in combination with the content of silicon, the risk of deformation of the limiting beam caused by the introduction of the silicon-based material can be reduced, and the cycle performance of the battery can be improved.

[0058] In some embodiments, the outer wall comprises a first side wall and a second side wall arranged at intervals along the thickness direction, the second side wall is located on the side of the first side wall away from the battery cell, and the first side wall comprises a first side surface. The plurality of reinforcing ribs comprises a first reinforcing rib connected to the first side wall. The expansion deformation of the battery cell during the cycle process will exert a force on the limiting beam, and the force is first applied to the first side wall. The first reinforcing rib connected to the first side wall can transmit the force to other parts of the outer wall and support 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 the cycle process will exert a force on the first side wall, and the component of the force along the thickness direction is large; the first reinforcing rib inclined relative to the thickness direction can decompose the force, thereby reducing the risk of crushing of the first reinforcing rib.

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

[0061] In some embodiments, the first reinforcing rib has an included angle of 30° to 80° with the thickness direction. By setting the included angle β to 30° to 80°, the pressure and torque received by the first reinforcing rib can be considered to some extent, the risk of crushing or rotational deformation of the first reinforcing rib can be reduced, the structural strength and rigidity of the limiting beam can be improved, and effective constraint of the battery cell can be provided.

[0062] In some embodiments, the first side wall comprises a middle region and two edge regions, the two edge regions extending from two ends of the middle region in a direction parallel to the first side and perpendicular to the extending direction of the limiting beam, and the middle region has the same size as the edge regions. The at least one first reinforcing rib is connected to the middle region.

[0063] During the circulation of the battery cells, the battery cells expand greatly along the center in the height direction of the battery cells, and the middle region of the first side wall is opposite to the center of the battery cells, so the force acting on the middle region is generally greater than the force acting on the edge regions. By connecting the at least one first reinforcing rib to the middle region, support can be provided to the middle region to inhibit the expansion deformation of the battery cells during the circulation.

[0064] In some embodiments, the outer wall comprises a first side wall and a second side wall spaced apart in the thickness direction, the second side wall being located on the side of the first side wall away from the plurality of battery cells, and the first side wall comprises a first side. The second side wall comprises a first section parallel to the first side wall and a second section extending from one end of the first section and inclined toward the first side wall. The at least one reinforcing rib is connected to the connection between the first section and the second section.

[0065] During the circulation of the battery cells, the battery cells expand and exert a force on the first side wall, part of the force being transmitted to the connection between the first section and the second section through the reinforcing rib, thereby dispersing the stress. The first section and the second section can both support the first side wall through the reinforcing rib to reduce the deformation of the first side wall.

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

[0067] By providing the partition wall and the reinforcing rib, the interior of the limiting beam can be formed into a multi-cavity structure, which is conducive to improving the overall rigidity of the limiting beam. During the circulation of the battery cells, the battery cells expand and exert a force on the first side wall, and the partition wall can transmit and disperse the force, thereby reducing the deformation of the first side wall and restraining the battery cells.

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

[0069] In some embodiments, the battery further comprises an insulating member arranged between the limiting beam and the shell. The insulating member can insulate the limiting beam from the shell, increase the creepage gap between the battery monomer and the limiting beam, reduce the risk of short circuit, and improve the reliability.

[0070] In some embodiments, the battery further comprises a constraint member connected to the limiting beams. During the cycle of the battery monomer, the battery monomer expands and exerts a force on the limiting beam. The constraint member can provide a constraint force to the limiting beam, thereby reducing the deformation of the limiting beam and limiting the expansion of the battery monomer, improving the cycle performance of the battery monomer, and reducing the risk of cracking of the box.

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

[0072] In some embodiments, the constraint member is bonded to the battery monomer. Through the bonding method, the stable connection between the battery monomer and the constraint member can be quickly achieved, and the constraint force of the constraint member on the battery monomer can be enhanced.

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

[0074] In some embodiments, the battery further comprises a fixing member connected to the constraint member and the limiting beam. At least part of the fixing member is embedded in the limiting beam and fixed with the limiting beam. The fixing member is embedded in the limiting beam, thereby improving 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 constraint member can be connected to the limiting beam through the fixing member, and the connection between the fixing member and the constraint member is not limited by the limiting beam, so that the connection mode between the fixing member and the constraint member can be flexibly selected according to the needs, and the connection strength between the fixing member and the constraint 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 arranging the receiving cavity, the fixing member can be embedded in the limiting beam as a whole, thereby 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. The constraint member is a plurality of constraint members, and the plurality of constraint members are arranged at intervals along the extension direction of the limiting beam. The plurality of constraint members can increase the constraint force on 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 cycle of the battery monomer, and improve the cycle performance of the battery.

[0077] In some embodiments, the battery further includes a plurality of busbar components electrically connecting the plurality of battery cells. The plurality of busbar components includes at least one first busbar component including a first busbar layer and a second busbar layer stacked and connected, the first busbar layer connecting at least two battery cells arranged along a thickness direction.

[0078] The first busbar component has at least a double-layer structure, and both the first busbar layer and the second busbar layer of the first busbar component can transmit current, so that the first busbar component has a higher overcurrent area, thereby reducing the heat generation of the first busbar component and improving the rapid charging capability of the battery. Under the premise that the overcurrent area meets the requirements, the first busbar component is arranged as a double-layer structure, which can reduce the thickness of the first busbar layer. The battery cell will swell during the cycle process, thereby stretching the first busbar layer. The first busbar layer has a smaller thickness, which is easy to deform to adapt to the deformation of the battery cell, reduces the risk of the connection between the battery cell and the first busbar layer being pulled apart, and improves the reliability of the battery.

[0079] In some embodiments, the battery cell includes an electrode terminal arranged on the shell, and the electrode terminal is electrically connected to the electrode assembly. The part of the first busbar layer that does not overlap with the second busbar layer is connected to the electrode terminal. The second busbar layer can avoid the connection between the first busbar layer and the electrode terminal, thereby reducing the influence of the second busbar layer on the connection between the first busbar layer and the electrode terminal when the battery cell swells, reducing the risk of the connection between the electrode terminal and the first busbar layer being pulled apart, and improving the reliability of the battery.

[0080] In some embodiments, the first busbar component includes at least one bending portion connecting the first busbar layer and the second busbar layer. The bending portion can connect the first busbar layer and the second busbar layer and transmit current between the first busbar layer and the second busbar layer, thereby improving the overcurrent capability of the first busbar component.

[0081] In some embodiments, the first busbar layer includes a first busbar portion, a second busbar portion, and a first buffer portion connecting the first busbar portion and the second busbar portion, the first busbar portion and the second busbar portion being arranged along a thickness direction and connected to different battery cells. The bending portion is arranged away from the first buffer portion.

[0082] During the cycle process of the battery cell, the battery cell swells and exerts a pulling force on the first busbar layer; the first buffer portion can release stress by deforming, thereby reducing the stress at the connection between the first busbar portion and the battery cell and the stress at the connection between the second busbar portion and the battery cell, and reducing the risk of the connection between the first busbar layer and the battery cell failing. 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 the deformation of the first buffer portion.

[0083] In some embodiments, the second busbar layer comprises a first layer portion, a second layer portion and a second buffer portion, the first layer portion is laminated with the first busbar portion and connected through at least one bending portion, and the second layer portion is laminated with the second busbar portion and connected through at least one bending portion. The second buffer portion connects the first layer portion and the second layer portion. In the lamination direction of the first busbar layer and the second busbar layer, the second buffer portion at least partially overlaps the first buffer portion.

[0084] During the cycle of the battery cell, the battery cell expands and exerts tension on the first busbar layer; both the first buffer portion and the second buffer portion can release stress through deformation, thereby reducing the risk of connection failure of the first busbar layer and the battery cell. The second buffer portion at least partially overlaps the first buffer portion, so that the deformation areas of the first buffer portion and the second buffer portion are close, thereby reducing the risk of interference of the first buffer portion and the second buffer portion with other parts when deformed.

[0085] In some embodiments, the second buffer portion and the first buffer portion are arranged in close contact, which can save space.

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

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

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

[0089] In some embodiments, the battery cell adjacent to the limiting beam is connected to the first busbar component. During charging, the expansion of the plurality of battery cells may be stacked in the thickness direction, which causes the displacement of the battery cell adjacent to the limiting beam to be larger; using the first busbar component with a double-layer structure to connect the battery cell close to the limiting beam can reduce the risk of connection failure of the first busbar component and the battery cell.

[0090] In some embodiments, the thickness of the first busbar layer is 1 mm-2.5 mm, and optionally 1.2 mm-1.8 mm. The thickness of the first busbar layer is selected according to the swelling pressure of the battery cell, so as to balance the overcurrent capacity of the first busbar layer and the deformability of the first busbar layer to some extent, thereby improving the rapid charging capacity and reliability of the battery.

[0091] In some embodiments, the thickness of the second busbar 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 busbar 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 busbar layer is less than or equal to 2.2 mm.

[0093] The swelling of the battery cell is related to the volumetric energy density thereof. In the present application, the thickness of the first busbar layer is designed according to the volumetric energy density of the battery cell, so as to balance the overcurrent capacity of the first busbar layer and the deformability of the first busbar layer to some extent, thereby improving the rapid 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 electrode current collector and a negative electrode film layer arranged 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 in the negative electrode active material is 1%-6%. The thickness of the first busbar layer is 1.2 mm-2.2 mm, and the thickness of the second busbar 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. The introduction of the silicon-based material also increases the swelling of the negative electrode sheet during the cycle process. The thickness of the first busbar layer and the thickness of the second busbar layer are designed in combination with the content of silicon, so as to reduce the risk of connection failure of the first busbar layer and the battery cell caused by the introduction of the silicon-based material, and meet the requirement for the overcurrent capacity of the first busbar component.

[0096] In some embodiments, the first busbar layer includes a first busbar portion, a second busbar portion, and a first buffer portion connecting the first busbar portion and the second busbar portion. The first busbar portion and the second busbar portion are arranged in the thickness direction and connected to different battery cells. In the stacking direction of the first busbar layer and the second busbar layer, the first buffer portion protrudes from the first busbar portion and the second busbar portion. The first busbar layer is provided with a recess at a position corresponding to the first buffer portion. By providing the recess, the strength of the first buffer portion can be reduced, and the deformation of the first buffer portion during the swelling of the battery cell can be facilitated.

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

[0098] The expansion of the battery cell is related to the volumetric energy density thereof. According to the volumetric energy density of the battery cell, the depth of the recess is designed in the application, so that the overcurrent capacity of the first buffer part and the deformability of the first buffer part are taken into account to some extent, so as to improve the rapid charging capacity and reliability of the battery.

[0099] In some embodiments, the battery cell is charged from 10% SOC to 80% SOC for 5-10.5 minutes. The battery cell has a rapid charging capacity, and the charging time can be saved.

[0100] In a second aspect, the embodiments of the application provide a power utilization device, which comprises the battery according to any of the embodiments of the first aspect, and the battery is used to provide electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0101] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments of the application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the application, and other drawings can be obtained by the drawings without creative labor for those skilled in the art.

[0102] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the application;

[0103] FIG. 2 is a schematic diagram of a battery according to some embodiments of the application;

[0104] FIG. 3 is an exploded schematic diagram of a battery cell according to some embodiments of the application;

[0105] FIG. 4 is a schematic diagram of a battery according to some embodiments of the application;

[0106] FIG. 5 is a sectional view of FIG. 4 along the direction of A-A;

[0107] FIG. 6 is an enlarged schematic diagram of the box in FIG. 5;

[0108] FIG. 7 is a schematic diagram of an electrode assembly according to some embodiments of the application;

[0109] FIG. 8 is a sectional view of the electrode assembly shown in FIG. 7;

[0110] FIG. 9 is a sectional view of a negative electrode tab of a battery cell according to some embodiments of the application;

[0111] FIG. 10 is a cross-sectional view of a negative tab of a battery cell according to some embodiments of the present application;

[0112] FIG. 11 is a cross-sectional view of a positive tab of a battery cell according to some embodiments of the present application;

[0113] FIG. 12 is a partial cross-sectional view of a battery according to some embodiments of the present application;

[0114] FIG. 13 is a partial cross-sectional view of a battery according to some embodiments of the present application;

[0115] FIG. 14 is a structural view of a battery according to some embodiments of the present application;

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

[0117] FIG. 16 is an enlarged view of the circle in FIG. 4;

[0118] FIG. 17 is a structural view of the first bus member of FIG. 16;

[0119] FIG. 18 is a connection view of a battery cell and a first bus member according to some embodiments of the present application;

[0120] FIG. 19 is a top view of a battery according to some embodiments of the present application;

[0121] FIG. 20 is an enlarged view of the square in FIG. 19;

[0122] FIG. 21 is a structural view of the second bus member of FIG. 20.

[0123] Reference signs are explained as follows

[0124] 1, vehicle; 2, battery; 3, controller; 4, motor;

[0125] 10, battery cell; 100, battery cell row; 10a, large face; 10b, narrow face;

[0126] 11, electrode assembly; 111, positive tab; 1111, positive current collector; 1112, positive film layer; 112, negative tab; 1121, negative current collector; 1122, negative film layer; 11221, first negative film layer; 11222, second negative film layer; 112a, flat layer; 113, separator; 11a, main body portion; 11b, positive tab; 11c, negative tab; 11d, first surface; 11e, second surface; 11f, third surface;

[0127] 12, housing; 121, case; 122, end cap; 13, electrode terminal;

[0128] 20, box

[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 surface; 21b, second side surface; 21c, third side surface;

[0130] 22, frame; 23, support beam; 24, bearing plate;

[0131] 30, insulating member; 40, restraining member; 50, adhesive layer; 60, fixing member;

[0132] 70, busbar component; 70a, first busbar component; 70b, second busbar component; 70c, third busbar component; 71, first busbar layer; 711, first busbar portion; 712, second busbar portion; 713, first buffer portion; 714, recess; 72, second busbar layer; 721, first laminated portion; 722, second laminated portion; 723, second buffer portion; 73, bent portion;

[0133] 80, fastener;

[0134] X, thickness direction; Y, extension direction; Z, height direction. DETAILED DESCRIPTION

[0135] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

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

[0137] Reference to "an embodiment" or "the embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" or "in the embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to one alternative embodiment versus another alternative embodiment.

[0138] In the description of the application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, can also be indirectly connected through intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0139] The term "and / or" in this application is only a description of the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this application generally represents that the front and rear associated objects have an "or" relationship.

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

[0141] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it is also expected that ranges of 60 to 110 and 80 to 120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1 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 a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" have been listed in this article; "0 to 5" is just a shortened representation of these numerical combinations. In addition, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0142] In this application, "multiple" means two or more (including two).

[0143] "Parallelism" includes not only absolutely parallel cases, but also roughly parallel cases as commonly understood in engineering. "Perpendicularity" includes not only absolutely perpendicular cases, but also roughly perpendicular cases as commonly understood in engineering.

[0144] Currently, judging from market trends, battery applications are becoming increasingly widespread. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in aerospace and other fields. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0145] A battery typically refers to a single physical module comprising multiple individual cells to provide higher voltage and capacity. The individual cell is the smallest unit that makes up a battery. During cycling, electrochemical reactions occur inside the cell, causing it to expand. As the individual cells expand, it affects the overall performance of the battery.

[0146] Therefore, to limit the expansion of individual battery cells, batteries are typically equipped with limiting beams to support and constrain the cells. The constraint imposed by these limiting beams on the battery cells affects their cycle performance.

[0147] Therefore, the battery provided by the embodiments of the present application effectively limits the expansion of the battery monomer and improves the cycle performance of the battery monomer by reasonably designing the battery monomer and the limiting beam.

[0148] The battery described in the embodiments of the present application is suitable for a power consumption device using the battery. The power consumption device can be a device using the battery as a power source or various energy storage systems using the battery as an energy storage element. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, and an electric aircraft toy, and the like. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

[0149] The following embodiments are described by taking a vehicle as an example for the convenience of description.

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

[0151] As shown in FIG. 1, the vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, the head, or the tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power source of the vehicle 1.

[0152] The vehicle 1 can further include a controller 3 and a motor 4, the controller 3 being used to control the battery 2 to supply power to the motor 4, for example, to meet the working power demand of the vehicle 1 during starting, navigation, and driving.

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

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

[0155] Referring to FIG. 2, in some embodiments, the battery 2 includes a box body 20 and a plurality of battery monomers 10 contained in the box body 20.

[0156] The battery monomer 10 can be a secondary battery, which refers to a battery monomer that can be activated by charging after discharging.

[0157] For example, the battery monomer 10 can be a lithium ion battery monomer, a sodium ion battery monomer, a sodium lithium ion battery monomer, a lithium metal battery monomer, a sodium metal battery monomer, a lithium sulfur battery monomer, a magnesium ion battery monomer, a nickel hydrogen battery monomer, a nickel cadmium battery monomer, a lead storage battery monomer, and the like.

[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 including a square battery cell, a blade battery cell, a multi-prismatic battery cell, such as a hexagonal battery cell, etc.

[0159] The plurality of battery cells 10 can be connected in series, in parallel, or in a mixed connection, the mixed connection referring to a connection in which both series and parallel connections are present among the plurality of battery cells 10. The plurality of battery cells 10 can be directly connected in series, in parallel, or in a mixed connection, and the plurality of battery cells 10 can be accommodated in the case 20 as a whole. Alternatively, the plurality of battery cells 10 can be connected in series, in parallel, or in a mixed connection to form a battery module, and a plurality of battery modules can be connected in series, in parallel, or in a mixed connection to form a whole, which can be accommodated in the case 20.

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

[0161] FIG. 3 is an exploded view of a battery cell according to some embodiments of the present application.

[0162] Referring to FIG. 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 an electrolyte is formed inside the housing 12. The shape of the housing 12 can be determined according to the specific shape of the electrode assembly 11. For example, if the electrode assembly 11 has a cuboid structure, a cuboid housing can be used.

[0164] As an example, the housing 12 includes a housing body 121 having an opening and an end cap 122 for closing the opening.

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

[0166] The housing body 121 and the end cap 122 can be separate components. As an example, an opening can be provided in the housing body 121, and the internal cavity of the battery cell 10 can be formed by closing the opening with the end cap 122.

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

[0168] The shape of the end cover 122 can be adapted to the shape of the shell 121 to fit the shell 121. The material of the end cover 122 can be the same as or different from that of the shell 121. Optionally, the end cover 122 can be made of a material with certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cover 122 is not easy to deform when subjected to extrusion and collision, so that the battery monomer 10 can have higher structural strength, and the reliability can also be improved.

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

[0170] The shell 121 can be open at one end or at both ends. In some examples, the shell 121 can be a structure open on one side, and the end cover 122 is provided as one and covers the shell 121. In other examples, the shell 121 can also be a structure open on both sides, and the end cover 122 is provided as two, and the two end covers 122 cover the two openings of the shell 121 respectively.

[0171] The electrode assembly 11 is a component in which electrochemical reactions occur in the battery monomer 10. The shell 121 can contain one or more electrode assemblies 11.

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

[0173] As an example, the positive electrode sheet and the negative electrode sheet have a portion with active material constituting the main body part 11a of the electrode assembly 11, and a portion without active material constituting the positive electrode tab 11b and the negative electrode tab 11c. The positive electrode tab 11b and the negative electrode tab 11c can be located together at one end of the main body part 11a or at two ends of the main body part 11a respectively.

[0174] In some embodiments, the electrode assembly 11 further includes a separator film arranged between the positive electrode sheet and the negative electrode sheet, which can prevent the positive and negative electrodes from short-circuiting and allow the 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 a laminated structure.

[0177] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets are alternately arranged.

[0178] As an example, a plurality of positive electrode sheets are arranged, and the negative electrode sheet is folded to form a plurality of folded segments arranged in layers, and one positive electrode sheet is clamped between adjacent folded segments.

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

[0180] As an example, a plurality of isolation films are arranged, and each isolation film is arranged between any adjacent positive electrode sheet or negative electrode sheet.

[0181] As an example, the isolation film is continuously arranged, and is arranged between any adjacent positive electrode sheet or negative electrode sheet by folding or winding.

[0182] In some embodiments, the battery cell 10 further comprises an electrode terminal 13 arranged on the shell 12; the electrode terminal 13 can be used to electrically connect with the electrode assembly 11 to input or output electric energy.

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

[0184] FIG. 4 is a schematic diagram of a battery according to some embodiments of the present application; FIG. 5 is a cross-sectional view of FIG. 4 taken along the A-A direction; FIG. 6 is an enlarged view of the box in FIG. 5; FIG. 7 is a schematic diagram of an electrode assembly according to some embodiments of the present application; and FIG. 8 is a cross-sectional view of the electrode assembly shown in FIG. 7.

[0185] Referring to FIGS. 4-8, the embodiments of the present application provide a battery 2 comprising a plurality of battery cells 10 and a box 20. The plurality of battery cells 10 are arranged along the thickness direction X of the battery cell 10. The battery cell 10 comprises a shell 12 and an electrode assembly 11 contained in the shell 12. The box 20 is used to contain the plurality of battery cells 10. The box 20 comprises at least two limiting beams 21, and the two 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 0.5-2.4 MPa. The limiting beam 21 comprises a first side surface 21a facing the plurality of battery cells 10, and the first side surface 21a is configured to have a maximum displacement in the thickness direction X of less than or equal to 8 mm under a pressure of 1.7 MPa.

[0186] The battery cells 10 between any two adjacent limiting beams 21 can be arranged in one row or multiple rows. Exemplarily, one row of battery cells 10 can constitute one 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 can 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] Discharge the battery cell 10 at a constant current discharge rate of 1C to 2.0V at an ambient temperature of 45°C;

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

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

[0193] According to the above charging strategy and the charging strategy, the battery cell is subjected to cyclic charging and discharging 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 the maximum pressure exerted by the battery cell on the clamping plate is recorded;

[0194] The expansion pressure Q of the battery cell in the thickness direction is calculated as: maximum pressure / large face area.

[0195] The limiting beam 21 can be two or more. As an example, at least one battery cell row 100 is arranged 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 the battery cell 10 in the thickness direction X; alternatively, other components can be arranged between the limiting beam 21 and the battery cell 10, i.e., the limiting beam 21 limits the expansion of the battery cell 10 through the components.

[0197] Exemplarily, the first side surface 21a of the limiting beam 21 can be a vertical plane for opposing 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) dismount the battery cell 10 of the battery 2 and fix the case 20 of the battery 2 to a clamp;

[0200] (II) abut the pressure head of the pressure testing machine with the first side surface 21a of the limiting beam 21, wherein the pressure surface of the pressure head abutting 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 pressure head and move the pressure head in the thickness direction X of the battery cell 10, and record the maximum displacement E of the pressure head. Exemplarily, the area of the pressure surface is S, and F / S is 1.7 MPa.

[0202] As an example, when the pressure head abuts the middle region of the first side surface 21a in 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 density of the electrode assembly 11. The limiting beam of the embodiment has 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 density of the electrode assembly 11 and improving the energy density of the battery cell 10. The expansion pressure of the battery cell 10 in the thickness direction X is less than or equal to 2.4 MPa, and the limiting beam 21 has high deformation resistance, so that the limiting beam 21 can effectively constrain the battery cell 10 in the thickness direction X, so as to reduce the deformation of the electrode assembly 11 in the cycle process, reduce the risk of crease deformation of the separator of the electrode assembly 11 and the risk of local increase in the distance between the positive and negative electrode sheets, reduce polarization, and improve the cycle performance of the battery cell 10. By controlling the expansion pressure of the battery cell within a reasonable range and designing the limiting beam 21 accordingly, the deformation of the battery cell 10 and the limiting beam can be reduced, the risk of cracking of the case 20 can be reduced, and the cycle performance of the battery cell 10 can be improved.

[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 are connected to the two first surfaces 11d. The area of the first surface 11d is greater than the area of the second surface 11e.

[0205] Opposing the first surface 11d with a larger area to the first side surface 21a along the thickness direction X can increase the stress 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, reduce local deformation of the limiting beam 21, improve the consistency of stress of the electrode assembly 11, and improve the cycle performance of the battery cell 10 when the electrode assembly 11 expands.

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

[0208] In some embodiments, the two second surfaces 11e are oppositely arranged along the extension direction Y of the limiting beam 21. The extension direction Y of the limiting beam 21 can be perpendicular to the thickness direction X. For example, 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 part 11a includes two first surfaces 11d, two second surfaces 11e and two third surfaces 11f, the two third surfaces 11f are located at two ends of the battery cell 10 along the height direction Z, and the third surfaces 11f are connected to the two first surfaces 11d and the two second surfaces 11e.

[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 the two third surfaces 11f respectively.

[0211] In some embodiments, at least part of the second surface 11e is arc-shaped. Optionally, the electrode assembly 11 is a winding 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 faces 10a and two narrow faces 10b, the two large faces 10a are oppositely arranged along the thickness direction X, the two narrow faces 10b are oppositely arranged along the extension direction Y, and the two ends of the large face 10a along the extension direction Y are connected to the two narrow faces 10b. The area of the large face 10a is greater than the area of the narrow face 10b.

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

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

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

[0216] The embodiments of the present application limit the expansion pressure of the battery cell 10 in the thickness direction X to 1.5 MPa-2.0 MPa, so as 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] FIG. 9 is a schematic view of a negative electrode sheet of a battery cell according to some embodiments of the present application.

[0219] Referring to FIGS. 8 and 9, 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 arranged 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.

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

[0221] Optionally, the negative electrode current collector 1121 is provided with the negative electrode film layer 1122 on both surfaces thereof opposite along the thickness direction thereof. The negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 can be made of the same negative electrode active material or different negative electrode active materials, and the thicknesses of the negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 can be the same or different.

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

[0223] In some embodiments, the negative current collector 1121 can employ 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 can be employed. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer can include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0224] In some embodiments, the thickness of the negative current collector 1121 is 4 μm to 6 μm. Illustratively, the thickness of the negative current collector 1121 is 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, or a range defined by any two of the aforementioned values.

[0225] In some embodiments, the compaction density of the negative film layer 1122 at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 . Illustratively, the compaction density of the negative film layer 1122 at 100% state of charge of the battery cell 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 defined by any two of the aforementioned values.

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

[0227] The battery cell is charged to a battery charging upper limit voltage at a constant current charging rate of 0.33C, and then charged to a state corresponding to 100% SOC of the battery cell at a constant voltage of 0.05C. The battery cell is discharged to a cut-off voltage at a constant current discharging rate of 0.33C, and the state corresponds to 0% SOC of the battery cell. Illustratively, the battery charging upper limit voltage can be 3.8V; the battery discharging cut-off voltage can be 2.0V.

[0228] Illustratively, the compaction density of the negative electrode film layer of the battery cell at 100% state of charge is a meaning known in the art, that is, the negative electrode film layer of the battery cell at 100% SOC is disassembled to obtain a negative electrode sheet, and the compaction density of the negative electrode film layer is measured; for example, a single-sided coated negative electrode sheet (if it is a double-sided coated negative electrode sheet, the negative electrode film layer on one side can be wiped off first), cut into a small round piece with an area of S1, weighed, recorded as M1, and its thickness H1 is measured. Then wipe off the negative electrode film layer of the above weighed negative electrode sheet, weigh the negative electrode current collector, record as M0, and measure its thickness H0. The single-sided coating weight of the negative electrode film layer = (the weight of the negative electrode sheet M1-the weight of the negative electrode current collector M0) / S1, the thickness of the negative electrode film layer = the thickness of the negative electrode sheet H1-the thickness of the negative electrode current collector H0, and the compaction density of the negative electrode film layer = the single-sided coating weight of the negative electrode film layer / the thickness of the negative electrode film layer.

[0229] The compaction density of the negative electrode film layer 1122 is related to the expansion of the battery cell 10 at 100% state of charge, and the compaction density of the negative electrode film layer 1122 is limited to 1.15g / cm 3 1.36g / cm 3 , which can balance the energy density and expansion pressure of the battery cell 10 to a certain extent, 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 in the above range, it is beneficial to improve the energy density of the battery cell 10; and because the negative electrode active material in the negative electrode film layer 1122 is packed more tightly, the contact resistance between particles is smaller, 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 in the above range, the rapid charging capability of the battery cell 10 can be improved. The smaller the compaction density of the negative electrode film layer 1122, the greater the porosity of the negative electrode sheet 112, the slower the expansion of the negative electrode sheet, and the smaller the expansion pressure of the battery cell 10.

[0232] In some embodiments, the compaction density of the negative electrode film layer 1122 of the battery cell at 100% SOC is 1.25g / cm 3 1.36g / 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 . Illustratively, 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 consisting of any two of the above values.

[0234] The single-side coating weight of the negative electrode film layer 1122 is related to the expansion of the negative electrode film layer. The single-side coating weight of the negative electrode film layer 1122 is limited to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , which can balance the energy density and the expansion pressure of the battery monomer 10 to some extent, and reduce the deformation of the battery monomer 10 and the limiting beam 21.

[0235] In addition, the single-side coating weight of the negative electrode film layer 1122 is limited to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , which can also limit the heat generation per unit area of the negative electrode sheet 112, and reduce the temperature rise of the battery monomer 10, especially during rapid charging.

[0236] In some embodiments, the single-side coating weight of the negative electrode film layer 1122 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 , which can further balance the energy density and the expansion pressure of the battery monomer 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. As an example, when the battery monomer is at 0% state of charge, a double-sided coated negative electrode sheet is taken; the porosity of the negative electrode sheet is measured by a true density instrument AccuPyc II 1340 according to the national standard GB / T 24586-2009.

[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 of the negative electrode sheet 112, slow down the expansion of the negative electrode sheet 112, reduce the expansion pressure of the battery monomer 10, reduce the deformation of the battery monomer 10 and the limiting beam 21, and improve the cycle performance of the battery monomer 10. The porosity of the negative electrode sheet 112 is less than or equal to 40%, which can balance the energy density of the battery monomer 10.

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

[0241] When the graphitization degree of the graphite particles is in the above range, the electrical conductivity of the graphite particles is relatively excellent, which can reduce the heat generation of the negative electrode sheet 112 and the battery monomer 10, and improve the rapid charging performance of the battery monomer 10.

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

[0243] In some embodiments, the negative active material comprises a silicon-based material. The introduction of the silicon-based material can improve the capacity of the negative active material and increase the energy density of the battery monomer 10.

[0244] In some embodiments, the mass content of silicon in the silicon-based material in the negative active material is 0.3% to 10%. For example, the mass content of silicon in the negative active material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or a range defined by any two of the above values.

[0245] The introduction of the silicon-based material in the negative electrode sheet 112 can not only improve the capacity, but also increase the expansion of the negative electrode sheet 112. Therefore, by limiting the mass content of silicon in the negative active material to 0.3% to 10%, the energy density and the expansion of the battery monomer 10 can be considered to a certain extent, the deformation of the battery monomer 10 and the limiting beam 21 is reduced, and the cycle performance of the battery monomer 10 is improved.

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

[0247] The qualitative and quantitative detection of each substance or element in the present application can be carried out by using suitable equipment and methods known to those skilled in the art, and the relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc., and those skilled in the art can also adaptively change certain detection steps / instrument parameters from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used for qualitative or quantitative determination.

[0248] For example, the silicon-based material can be subjected to X-ray powder diffraction test and qualitative analysis by JIS / K0131-1996 X-ray Diffraction Analysis Method General Rules on the negative electrode sheet or the negative electrode active material.

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

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

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

[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 adopt a single-layer film layer or at least two film layers. Alternatively, the negative electrode film layer 1122 includes at least two film layers.

[0253] In the case where the negative electrode film layer 1122 adopts a single-layer film layer, the negative electrode active material in the negative electrode film layer 1122 includes the carbon-based material and optionally the silicon-based material. In the case where a single-layer film layer is adopted, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm to 13.5 μm. Illustratively, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, or a range consisting of any two of the above values.

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

[0255] FIG. 10 is a cross-sectional schematic view of a negative electrode sheet of a battery cell according to some embodiments of the present application.

[0256] Referring to FIG. 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, and the second negative electrode film layer 11222 is arranged between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material arranged in the first negative electrode film layer 11221 and a second negative electrode active material arranged in the second negative electrode film layer 11222, and the first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and a silicon-based material.

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

[0258] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be differentially arranged, so as to balance the expansion and capacity of the negative electrode film layer 1122 to some extent; the double-layer coating can construct the pore difference of the negative electrode film layer 1122, reduce the ion transmission tortuosity, reduce the side reaction, and improve the rapid charging performance of the battery cell 10.

[0259] The artificial graphite can have a relatively small volume average particle size Dv50, which on the one hand can shorten the solid-phase transmission path of lithium ions and improve the rapid charging performance, and on the other hand, the material is not easy to agglomerate during preparation, 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 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 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 lithium ion transmission tortuosity can be reduced, and the rapid charging capability 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 rapid charging capability of the battery cell 10.

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

[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] The difference in particle size of the first negative electrode active material and the second negative electrode active material can improve the rapid charging performance of the battery cell 10. During rapid charging, the overpotential of the first negative electrode film layer 11221 is usually high, and the bottleneck of rapid charging is mainly in the first negative electrode film layer 11221. In the present application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transmission path of ions, improve the rapid charging performance, and improve the problem of ion precipitation on the surface 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, reducing the expansion of the negative electrode film layer 1122 and 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 7.8-14.3 μm, which can be 7.8-11.3 μm. Illustratively, 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 a range formed by 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, which can shorten the solid-phase transmission path of lithium ions, improve the rapid charging performance, on the one hand; on the other hand, the material is not easy to agglomerate during preparation, which can improve the stability of the material; on the other hand, the first negative electrode active material with the above volume average particle size range can cooperate with the second negative electrode active material, which is beneficial to build a gradient pore difference of the first negative electrode film layer 11221 and the second negative electrode film layer 11222, reduce the tortuosity of lithium ion transmission, and improve the rapid charging performance of the battery monomer 10.

[0268] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% of the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% of the volume distribution, which can be detected by using devices and methods known in the art, for example, taking the negative electrode active material as a sample, and testing the Dv50 and Dv10 of the particles by a Mastersizer 2000E laser particle size analyzer according to the test standard GB / T 19077-2016.

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

[0270] For example, 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 a range formed by any two of the above values.

[0271] The volume average particle size Dv50 of the second negative electrode active material is 9.5 um-18.5 μm, which can make the pores of the second negative electrode film layer 11222 more abundant, which is beneficial to improve the rapid charging capacity of the battery monomer 10 and reduce the expansion 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, which 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, which 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 active material is 0.5m 2 / g-3m 2 / g, optionally 0.6m 2 / g-1.2m 2 / g. Exemplarily, the specific surface area of the negative active material is 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1.0m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g, 2.0m 2 / g, 2.1m 2 / g, 2.2m 2 / g, 2.3m 2 / g, 2.4m 2 / g, 2.5m 2 / g, 2.6m 2 / g, 2.7m 2 / g, 2.8m 2 / g, 2.9m 2 / g, 3.0m 2 / g, or a range between any two of the above values.

[0275] The specific surface area of the material is the meaning known in the art, which can be detected by using devices and methods known in the art, for example, according to the test standard GB / T 19587-2017, taking the negative active material as a sample, and using a Tri-Star 3020 specific surface area and pore size analyzer of the United States Micromeritics Company to test the specific surface area.

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

[0277] FIG. 11 is a cross-sectional view of a positive electrode sheet of a battery cell according to some embodiments of the present application.

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

[0279] For example, the positive electrode current collector 1111 has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer 1112 is disposed on either 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, which is a lithium-containing phosphate. The lithium-containing phosphate has high cycle stability, and use of the lithium-containing phosphate as the positive electrode active material can improve cycle degradation of the battery cell 10 due to excessive temperature rise during fast charging.

[0281] In some embodiments, the positive electrode film layer 1112 has a compaction density of 2.50 g / cm 3 to 2.80 g / cm 3 at 100% SOC of the battery cell 10. 3 For example, the positive electrode film layer 1112 has a compaction density of 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 a range defined by any two of the above values. 3

[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 electrode active material in the positive electrode film layer 1112 is packed more tightly and the contact resistance between particles is smaller, it can further reduce the resistance of the positive electrode sheet 111, thereby reducing the heat generation under fast charging.

[0283] In this embodiment, the compaction density of the positive electrode film 1112 at 100% SOC of the battery cell is a term known in the art, meaning that the positive electrode sheet 111 is disassembled from the battery cell 10 at 100% SOC, and the compaction density of the positive electrode film 1112 is measured. Exemplarily, the method for testing the compaction density of the positive electrode film 1112 can be the same as the method for testing the compaction density of the negative electrode film 1122.

[0284] In some embodiments, the single-sided coating weight of the positive electrode film 1112 is 200 mg / 1540 mm. 2 -370mg / 1540 / mm 2 ; 240mg / 1540mg is optional 2 Up to 330mg / 1540mm 2 For example, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540.25 mm. 2 210mg / 1540.25mm 2 220mg / 1540.25mm 2 230mg / 1540.25mm 2 240mg / 1540.25mm 2 250mg / 1540.25mm 2 260mg / 1540.25mm 2 270mg / 1540.25mm 2 280mg / 1540.25mm 2 290mg / 1540.25mm 2 300mg / 1540.25mm 2 310mg / 1540.25mm 2 320mg / 1540.25mm 2 330mg / 1540.25mm 2 340mg / 1540.25mm 2 350mg / 1540.25mm 2 360mg / 1540.25mm 2 370mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0285] In the embodiments of the present application, the single-side coating weight of the positive electrode film layer 1112 is in the meaning known in the art, which can be detected by using the devices and methods known in the art, and the detection method is the same as the single-side coating weight test method of the negative electrode film layer 1122.

[0286] The single-side coating weight of the positive electrode film layer 1112 is set to 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 The heat generation per unit area of the positive electrode sheet 111 can be limited, and the energy density and the charge rate performance of the battery monomer 10 can be improved.

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

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

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

[0290] In some embodiments, the thickness of the positive electrode sheet 111 can be 0.13 mm-0.2 mm. For example, the thickness of the positive electrode sheet 111 can be 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, or a range formed by any two of the above values.

[0291] In the embodiments of the present application, the thickness of the positive electrode sheet 111 is in the meaning known in the art, which can be detected by using the devices and methods known in the art, for example, using a micrometer to measure the thickness of the positive electrode sheet 111.

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

[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. Illustratively, in the embodiments of the present application, the thickness of the positive electrode film layer 1112 is the thickness of the positive electrode film layer 1112 on one side of the positive electrode current collector 1111.

[0294] Illustratively, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, or a range defined by any two of the above values.

[0295] Limiting the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be greater than or equal to 0.05 can improve the flow capacity of the positive electrode current collector 1111, reduce the temperature rise of the positive electrode sheet 111, and improve the rapid charging performance of the battery monomer 10. Limiting the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be less than or equal to 0.3 can reduce the loss of capacity of the positive electrode sheet 111. The embodiments of the present application limit the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be 0.05 to 0.3, which can balance the rapid charging capacity and energy density of the battery monomer 10 to a certain extent.

[0296] The thickness of the positive electrode film layer and the thickness of the positive electrode current collector are well-known meanings in the art, which can be detected by using well-known devices and methods in the art. For example, the thickness of the positive electrode sheet can be measured by using a micrometer, the thickness of the positive electrode current collector can be measured by removing the film layer on the surface of the positive electrode current collector, and the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector when the positive electrode film layer is single-sided coated. When the positive electrode film layer is double-sided coated, the thickness of the positive electrode film layer is (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector) / 2.

[0297] In some embodiments, the thickness of the positive electrode current collector 1111 is 10 μm to 15 μm, which can be 12 μm to 15 μm. Illustratively, the thickness of the positive electrode current collector 1111 is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, or a range defined by any two of the above values. When the thickness of the positive electrode current collector 1111 is within the above range, the flow capacity of the positive electrode current collector 1111 is relatively excellent, and the battery monomer 10 can have a relatively high energy density.

[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 the positive electrode tab 11b.

[0299] In some embodiments, the positive electrode active material comprises a lithium-containing phosphate of olivine structure or a modified material thereof.

[0300] The lithium-containing phosphate of olivine structure or the modified material thereof can be a lithium-containing phosphate of olivine structure or a material obtained after coating modification. For example, the lithium-containing phosphate of olivine structure comprises phosphate particles and an ion-conducting layer, the ion-conducting layer coating the phosphate particles, the ion-conducting layer containing one or more elements of C, Fe, Ti, Zr, Hf, Ge and Sn.

[0301] In some embodiments, the mass fraction of the lithium-containing phosphate of olivine structure or the modified material thereof in the positive electrode active material can be greater than or equal to 80% and less than or equal to 100%, and the positive electrode active material of the present application can be considered as a lithium-containing phosphate of olivine structure or a modified material thereof system. When the mass fraction of the lithium-containing phosphate of olivine structure or the modified material thereof is less than 100%, the positive electrode active material can further comprise a commonly used positive electrode active material, for example, can comprise but is not limited to at least one of a lithium-containing transition metal oxide. Examples of the lithium-containing transition metal oxide can comprise but are not limited to at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and a modified compound of each thereof.

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

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

[0304] Exemplarily, the Dv50 of the positive electrode active material can be 1 μm, 1.1 μm, 1.15 μm, 1.2 μm, 1.25 μm, 1.3 μm, 1.35 μm, 1.4 μm, 1.45 μm, 1.5 μm, 1.55 μm, 1.6 μm, 1.65 μm, 1.7 μm, 1.75 μm, 1.8 μm, 1.85 μm, 1.9 μm, 1.95 μm, 2 μm or a range formed by any two of the above values.

[0305] Exemplarily, the Dv10 of the positive electrode active material can be 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm or a range formed by any two of the above values.

[0306] The particle size of the positive electrode active material is relatively small, the lithium ion deintercalation lithium path in the positive electrode active material is short, and the heat production is less; and the particle size of the positive electrode active material is not too small, and the agglomeration can be reduced in the processing and preparation process, so that the performance of the positive electrode active material is stable.

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

[0308] In some embodiments, the battery cell 10 includes an electrolyte contained in the shell 12. During the charging and discharging of the battery cell 10, active ions are embedded and de-embedded between the positive electrode sheet 111 and the negative electrode sheet 112, and the electrolyte plays a role in conducting active ions between the positive electrode sheet 111 and the negative electrode sheet 112.

[0309] In some embodiments, the electrolyte has an electrical conductivity of 13 mS / cm to 20 mS / cm at room temperature, which can be 15 mS / cm to 20 mS / cm. For example, the electrolyte has an electrical conductivity of 13 mS / cm, 13.5 mS / cm, 14 mS / cm, 14.5 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 16.5 mS / cm, 17 mS / cm, 17.5 mS / cm, 18 mS / cm, 18.5 mS / cm, 19 mS / cm, 19.5 mS / cm, 20 mS / cm or a range formed by any two of the above values at room temperature.

[0310] For example, the room temperature can be 25°C.

[0311] When the electrical conductivity of the electrolyte is in the above range, the migration rate of ions in the electrolyte is high, thereby further reducing the internal resistance of the battery cell 10, reducing heat production, and improving the rapid charging performance of the battery cell 10.

[0312] The electrical conductivity of the electrolyte is the ionic conductivity, which can be detected by using devices and methods known in the art, for example, the industry standard HG-T 4067-2015 is referred to for testing.

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

[0314] Exemplarily, the density p of the electrolyte is 1.05 g / mL, 1.10 g / mL, 1.15 g / mL, 1.2 g / mL, 1.25 g / mL, 1.3 g / mL, 1.35 g / mL, or a range formed by any two of the above values.

[0315] When the density p of the electrolyte is in the above range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery monomer 10, thereby reducing the heat generation and improving the rapid charging performance of the battery monomer 10.

[0316] In the embodiments of the present application, the density of the electrolyte is the meaning known in the art, which can be detected by using the devices and methods known in the art, for example, referring to GB / T 2013-2010 for testing.

[0317] In some embodiments, the electrolyte comprises an organic solvent, and the organic solvent comprises one or more of a carbonate-based solvent and a carboxylate-based solvent.

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

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

[0320] In some embodiments, the carboxylate comprises R1-COO-R2, and R1 and R2 each independently comprises an alkyl group with 1-5 carbon atoms or a halogenated alkyl group with 1-5 carbon atoms. The above chain carboxylate-based solvent has a relatively high conductivity, which is beneficial to improving the rapid charging capability of the battery monomer 10.

[0321] In some embodiments, the carbonate-based solvent comprises one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0322] Further optionally, the carbonate-based solvent comprises one or more of vinyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.

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

[0324] Further optionally, the mass content of the carbonate-based solvent in the organic solvent is 5% to 95%, optionally 25% to 60%, optionally 30% to 45%. Illustratively, the mass content of the carbonate-based solvent in the organic solvent is 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60%, or a range between any two of the foregoing values. The carbonate-based solvent in the above mass content can further improve the conductivity of the electrolyte, which is conducive to the migration of lithium ions.

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

[0326] The organic solvent can improve the conductivity and reduce the viscosity of the electrolyte, thereby improving the rapid charging performance of the battery 2.

[0327] In some embodiments, the electrolyte includes a lithium salt. The lithium salt includes one or more of a fluorine-containing sulfimide salt and lithium hexafluorophosphate LiPF6. The above lithium salt is easy to dissociate, which is conducive to the rapid migration of lithium ions; and the electrolyte system is relatively stable and is not easy to decompose, which can improve the cycle performance of the battery monomer 10.

[0328] Optionally, the fluorine-containing sulfimide salt includes one or more of lithium bisfluorosulfimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI.

[0329] In some embodiments, the lithium salt includes lithium bisfluorosulfimide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L. Illustratively, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.4 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.7 mol / L. Illustratively, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L. Illustratively, the molar concentration of lithium bisfluorosulfimide LiFSI is 0.2 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.8 mol / L.

[0330] Optionally, the ratio of the molar concentration of lithium bisfluorosulfonylimide to the molar concentration of lithium hexafluorophosphate LiPF6 is (2 to 5):10. Illustratively, the ratio of the molar concentration of lithium bisfluorosulfonylimide to the molar concentration of lithium hexafluorophosphate LiPF6 is 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10, 5:10, or a range defined by any two of the foregoing.

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

[0332] The negative electrode sheet 112 includes at least one flat layer 112a perpendicular to the thickness direction X, and the electrode assembly 11 has N layers of the flat layer 112a.

[0333] Illustratively, 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] Illustratively, the electrode assembly 11 has a jelly-roll structure, and the negative electrode sheet 112 includes N flat layers 112a; alternatively, the electrode assembly 11 has a stack structure, and the electrode assembly 11 includes N negative electrode sheets 112, each of which includes one flat layer 112a.

[0335] During the cycling of the battery cell 10, the negative electrode sheet 112 increases in thickness due to irreversible side reactions, causing the battery cell 10 to swell; limiting (N×T1) / T to 0.3-0.5 can reduce the swelling 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 rows 100 are arranged between the two adjacent limiting beams 21, the plurality of battery cell rows 100 are arranged in a direction perpendicular to the thickness direction X, and each battery cell row 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 of the battery cell row 100 in the thickness direction X is D2; 85%≤D2 / D1≤92%.

[0337] Illustratively, the first side surfaces 21a of the two adjacent limiting beams 21 are oppositely arranged, 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 a position of the limiting beam 21 that overlaps with the battery monomer 10 in the thickness direction.

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

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

[0341] D2 / D1 is related to the expansion pressure of the battery monomer 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 monomer 10, reduce the deformation of the limiting beam 21 and the battery monomer 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 in the thickness direction X and improve the energy density of the battery 2. D2 / D1 is limited to 85%-92% to balance the expansion pressure of the battery monomer 10 and the energy density of the battery 2 to a certain extent.

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

[0343] When the limiting beam 21 is subjected to a force due to the expansion of the battery monomer 10 during the cycle of the battery monomer 10, the second side surface 21b can decompose the force by inclination, thereby improving the deformation resistance of the limiting beam 21 and reducing the deformation or displacement of the first side surface 21a; the first side surface 21a can provide stronger constraint to the battery monomer 10 to reduce the expansion deformation of the battery monomer 10 and improve the cycle performance of the battery monomer 10. Compared with the scheme of improving the deformation resistance of the limiting beam 21 by increasing the limiting beam 21 as a whole, the scheme of improving the deformation resistance of the limiting beam 21 by using the inclined second side surface 21b can reduce the weight of the limiting beam 21 and improve the energy density of the battery 2.

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

[0345] The included angle α is greater than or equal to 1°, so that the limiting beam 21 has high structural strength and rigidity, and the deformation resistance of the limiting beam 21 is reduced. The included angle α is less than or equal to 25°, so that the maximum size of the limiting beam 21 in the thickness direction X is limited, thereby saving space and improving the space utilization of the limiting beam 21 in the thickness direction X.

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

[0347] In the embodiments of the present application, the volumetric energy density of the battery cell 10 is the meaning known in the art, which can be detected by using the devices and methods known in the art.

[0348] The expansion of the battery cell 10 is related to its volumetric energy density. In the present application, the included 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 the expansion pressure and the energy density to a certain extent.

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

[0350] The expansion of the battery cell 10 is related to its volumetric energy density. In the present application, the included 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 the expansion pressure and the energy density to a certain extent.

[0351] The battery cell 10 of the embodiments of the present application has a higher energy density, and the expansion pressure of the battery cell 10 is also greater. Increasing the included angle α can make the limiting beam 21 provide more constraint force for the battery cell 10, thereby improving the cycle 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 arranged 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 included angle α between the first side 21a and the second side 21b is 8-25°.

[0353] By introducing silicon oxide compounds or silicon-carbon composites, the capacity of the negative electrode sheet 112 can be improved, and the energy density of the battery monomer 10 can be improved. By introducing silicon oxide compounds and silicon-carbon composites, the expansion of the negative electrode sheet 112 during the cycle process is increased. By setting the included angle α to 8°-25°, the anti-deformation ability of the limiting beam 21 can be improved, thereby providing constraint for the expansion of the battery monomer 10, and reducing the risk of cycle attenuation of the battery monomer 10 caused by the introduction of silicon oxide compounds or silicon-carbon composites.

[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 conducive to improving the structural strength and rigidity of the limiting beam 21. Alternatively, the limiting beam 21 can also be spliced by multiple components, for example, the limiting beam 21 is spliced by multiple sheet metal parts.

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

[0356] The limiting beam 21 can be a hollow beam structure integrally formed by stamping / extruding or metal casting process. The wall thickness of the limiting beam 21 can be 1mm-8mm according to actual needs, and 3mm-5mm is commonly used. Within this wall thickness, the limiting beam 21 has good cost performance, has relatively light weight, and has good structural strength, which can effectively suppress the expansion deformation of the battery monomer 10 during the cycle process.

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

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

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

[0360] The support beam 23 can be one or multiple.

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

[0362] During the cycle process of the battery 2, the limiting beam 21 is used to resist the expansion force of the battery monomer 10 during the cycle process, and the frame body 22 can support the limiting beam 21 through the support beam 23, thereby providing effective support for the limiting beam 21, reducing the deformation of the limiting beam 21, and further providing constraint for the battery monomer 10, reducing the expansion of the battery monomer 10, and improving the cycle life of the battery monomer 10.

[0363] By setting the support force of the connecting frame body 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 body 22 includes a plurality of side beams arranged in sequence and connected to form a ring-shaped frame body 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 can be rectangular, trapezoidal, elliptical, circular, L-shaped or other shapes.

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

[0367] In some embodiments, the support beam 23 and the frame body 22 can be fixedly connected by welding, bolting or clamping.

[0368] In some embodiments, the limiting beam 21 extends along a direction perpendicular to the thickness direction X. The box body 20 includes a plurality of support beams 23 arranged at intervals along the extension direction Y of the limiting beam 21. The plurality of support beams 23 can increase the constraint force on the limiting beam 21, improve the uniformity of the stress on different regions of the limiting beam 21, reduce the deformation of the limiting beam 21 during the cycle of the battery monomer 10, and improve the cycle performance of the battery 2.

[0369] In some embodiments, the battery 2 further includes an insulating member 30 arranged 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 gap between the battery monomer 10 and the limiting beam 21, reduce the risk of short circuit, and improve 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] FIG. 12 is a partial cross-sectional view of a battery according to some embodiments of the present application.

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

[0373] The third side surface 21c can limit the maximum size of the limiting beam 21 in the thickness direction X, thereby improving the space utilization. In combination with the second side surface 21b, the third side surface 21c can also make the limiting beam 21 form a cross section similar to a trapezoid, thereby improving the structural strength and rigidity 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 box 20 further comprises a bearing plate 24, and the plurality of battery monomers 10 and the limiting beam 21 are located on the same side of the bearing plate 24 and are fixed to the bearing plate 24. As an example, the bearing plate 24 and the plurality of battery monomers 10 are arranged along the height direction Z of the battery monomers 10.

[0376] In some embodiments, the box 20 further comprises a cover plate (not shown) arranged opposite to the bearing plate 24 along the height direction Z and fixed to the frame 22. The battery monomers and the limiting beam are located between the cover plate and the bearing plate.

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

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

[0379] In some embodiments, the second side surface 21b extends from one end of the third side surface 21c away from the bearing 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, and 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, thereby reducing the deformation of the limiting beam 21.

[0381] In addition, arranging the third side surface 21c as a vertical plane can facilitate the connection of 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 comprises an outer wall 211 and a plurality of reinforcing ribs 212, the outer wall 211 encloses a receiving cavity 213, and the plurality of reinforcing ribs 212 are arranged in the receiving cavity 213 and connected to the outer wall 211. The outer wall 211 comprises the first side surface 21a.

[0383] As an example, the outer wall 211 further comprises the second side surface 21b. Optionally, the outer wall 211 further comprises the third side surface 21c.

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

[0385] The accommodating cavity 213 can not only provide a deformation space for energy absorption of the limiting beam 21, but also reduce the overall weight of the limiting beam 21, which is conducive to improving the energy density of the battery 2. The reinforcing rib 212 can improve the structural strength and rigidity of the limiting beam 21, and improve the deformation resistance 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, the negative electrode active material includes a silicon-based material, the mass content of silicon in the negative electrode active material in the silicon-based material is 1%-6%, the thickness of the outer wall 211 is 2mm-7mm, and the thickness of the reinforcing rib 212 is 2mm-7mm.

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

[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 monomer 10 can be improved. By introducing the silicon-based material, the expansion of the negative electrode sheet 112 during the cycle process is increased. By designing the thickness of the outer wall 211 and the thickness of the reinforcing rib 212 according to the content of silicon, the risk of deformation of the limiting beam 21 caused by the introduction of the silicon-based material can be reduced, and the cycle 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 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 monomer 10, and the first side wall 2111 includes a first side surface 21a. The plurality of reinforcing ribs 212 includes 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 referred to as the first reinforcing rib 212a. In the limiting beam 21, all the reinforcing ribs 212 can be the first reinforcing rib 212a, or part of the reinforcing ribs 212 can be the first reinforcing rib 212a.

[0391] Exemplarily, the reinforcing ribs 212 can be integrally formed with the outer wall 211. Alternatively, the reinforcing ribs 212 can be separately formed from the outer wall 211, and the reinforcing ribs 212 can 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 cycle process can exert a force on the limiting beam 21, and the force is first exerted on the first side wall 2111. The first reinforcing rib 212a connected to the first side wall 2111 can transmit the force to other parts of the outer wall 211 and support the first side wall 2111, thereby improving the deformation resistance of the first side wall 2111.

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

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

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

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

[0397] The expansion and deformation of the battery cell 10 during the cycle process can exert a force on the first side wall 2111, and the component of the force along the thickness direction X is large; the first reinforcing rib 212a inclined relative to the thickness direction X can decompose the force, thereby reducing the risk of crushing the first reinforcing rib 212a.

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

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

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

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

[0402] The included angle β is set to 30°-80°, so that the pressure and torque on the first reinforcing rib 212a can be considered to some extent, the risk of crushing or rotational deformation of the first reinforcing rib 212a is reduced, the structural strength and rigidity of the limiting beam 21 are improved, and the battery monomer 10 is effectively constrained.

[0403] In some embodiments, the first side wall 2111 includes a middle region 21111 and two edge regions 21112, the two edge regions 21112 extend from both ends of the middle region 21111 in a direction parallel to the first side 21a and perpendicular to the extension direction Y of the limiting beam 21, and the size of the middle region 21111 is equal to that of the edge region 21112. The at least one first reinforcing rib 212a is connected to the middle region 21111.

[0404] During the circulation of the battery monomer 10, the battery monomer 10 expands greatly along the center in the height direction Z thereof, and the middle region 21111 of the first side wall 2111 is opposite to the center of the battery monomer 10, so that the force acting on the middle region 21111 is generally greater than that acting on the edge region 21112; the at least one first reinforcing rib 212a connected to the middle region 21111 can provide support for the middle region 21111 to inhibit the expansion deformation of the battery monomer 10 during the circulation.

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

[0406] In some embodiments, the number of the first reinforcing ribs 212a directly connected to the middle region 21111 is greater than that of the first reinforcing ribs 212a directly connected to the convenient 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 the first side wall 2111 and the 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 monomers 10, and the first side wall 2111 includes the first side 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 is inclined toward the first side wall 2111. The 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 do not require absolute parallelism, but can also be approximately parallel as generally recognized in engineering.

[0410] For example, the first section 21121 comprises the third side 21c, and the second section 21122 comprises the second side 21b.

[0411] During the circulation of the battery cells 10, the battery cells 10 expand and exert a force on the first side wall 2111, 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, so as to disperse the stress. The first section 21121 and the second section 21122 can both support the first side wall 2111 through the reinforcing rib 212, so as 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] FIG. 13 is a partial cross-sectional view of a battery according to some embodiments of the present application.

[0414] In some embodiments, the outer wall 211 comprises a first side wall 2111, a second side wall 2112 and a top wall 2113, the second side wall 2112 is located on the 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 comprises the first side 21a.

[0415] For 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 comprises a top surface, and the top surface connects the first side 21a and the second side 21b.

[0417] In some embodiments, the limiting beam 21 further comprises a partition wall 214 connected to the top wall 2113, and the partition wall 214 is located between the first side wall 2111 and the second side wall 2112 along the thickness direction X. 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 arranging the partition wall 214 and the reinforcing rib 212, the interior of the limiting beam 21 can be formed into a multi-cavity structure, which is conducive to improving the overall rigidity of the limiting beam 21. During the circulation of the battery cells 10, the battery cells 10 expand and exert a force on the first side wall 2111, and the partition wall 214 can transmit and disperse the force, thereby reducing the deformation of the first side wall 2111 and restraining the battery cells 10.

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

[0420] In some embodiments, the partition wall 214 comprises a third segment 2141 and a fourth segment 2142, the fourth segment 2142 extending from the upper end of the third segment 2141 along the height direction Z and being inclined relative to the third segment 2141.

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

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

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

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

[0425] In some embodiments, the outer wall 211 further comprises a bottom wall 2114, the bottom wall 2114 being arranged with the top wall 2113 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] FIG. 14 is a structural schematic diagram of a battery according to some embodiments of the present application, and FIG. 15 is a partial cross-sectional schematic diagram of the battery shown in FIG. 14.

[0428] Referring to FIGS. 14 and 15, in some embodiments, the battery 2 further comprises a constraint 40, the constraint 40 being connected to adjacent limiting beams 21.

[0429] The constraint 40 can be one or multiple.

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

[0431] The constraint 40 can be a strip structure, a line structure, a beam structure, or other structures. For example, the constraint 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 exerts a force on the limiting beam 21. The constraint 40 can provide a constraint force on the limiting beam 21, thereby reducing the deformation of the limiting beam 21 and limiting the expansion of the battery cell 10, improving the cycling performance of the battery cell 10, and reducing the risk of cracking of the box 20.

[0433] In some embodiments, the constraint 40 can exert a pre-tightening force on the adjacent limiting beam 21.

[0434] In some embodiments, the constraint 40 is in a belt structure. The belt structure has low cost and occupies small space. The constraint 40 in the belt structure can improve the space utilization inside the battery 2 and improve the energy density of the battery 2.

[0435] In some embodiments, the constraint 40 includes a metal belt. For example, the constraint 40 includes a steel belt.

[0436] In some embodiments, the constraint 40 is located at one side of the battery monomer 10 along the height direction Z. The constraint 40 can limit the battery monomer 10 in the height direction Z.

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

[0438] In some embodiments, one constraint 40 is connected to the battery monomer 10 of at least one battery monomer column 100. Alternatively, one constraint 40 is connected to the battery monomers 10 of two adjacent battery monomer columns 100.

[0439] In some embodiments, the constraint 40 is bonded to the battery monomer 10. Through the bonding mode, the stable connection between the battery monomer 10 and the constraint 40 can be quickly realized, and the constraint force of the constraint 40 on the battery monomer 10 can be enhanced.

[0440] In some embodiments, a glue layer 50 is provided between the constraint 40 and the battery monomer 10. For example, the glue layer 50 includes a structural member or double-sided adhesive.

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

[0442] The constraint 40 and the limiting beam 21 can be connected by, but not limited to, a bolt connection, a buckle connection, or other detachable connection modes.

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

[0444] The fixing member 60 can be entirely embedded in the limiting beam 21, or can be only partially embedded in the limiting beam 21. The fixing member 60 is fixed with the limiting beam 21.

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

[0446] The fixing member 60 can be fixed to the limiting beam 21 by welding, clamping, riveting, bolting, bonding or other means.

[0447] The fixing member 60 is embedded in the limiting beam 21, thereby improving 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 limited by the limiting beam 21, so that the connection mode between the fixing member 60 and the restraining member 40 can be flexibly selected as needed, and the connection strength between the fixing member 60 and the restraining member 40 is improved.

[0448] In some embodiments, the limiting beam 21 has a containing cavity 213 inside, and the fixing member 60 is contained in the containing cavity 213. By providing the containing cavity 213, the fixing member 60 can be embedded in the limiting beam 21 as a whole, thereby improving the connection strength between the fixing member 60 and the limiting beam 21.

[0449] Optionally, the limiting beam 21 is spliced from multiple sheet metal members, and the fixing member 60 can be fixed to the sheet metal members during splicing.

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

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

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

[0453] The multiple restraining members 40 can increase the restraining force on the limiting beam 21, improve the uniformity of the stress on different regions of the limiting beam 21, reduce the deformation of the limiting beam 21 during the circulation of the battery monomer 10, and improve the circulation performance of the battery 2.

[0454] FIG. 16 is an enlarged schematic view of the circular frame in FIG. 4; FIG. 17 is a structural schematic view of the first busbar component shown in FIG. 16; and FIG. 18 is a connection schematic view of the battery monomer and the first busbar component according to some embodiments of the present application.

[0455] Referring to FIG. 4 and FIGS. 16-18, in some embodiments, the battery 2 further includes multiple busbar components 70, and the multiple busbar components 70 electrically connect the multiple battery monomers 10.

[0456] The plurality of bus members 70 can be connected in series, in parallel, or in a mixed connection.

[0457] The plurality of bus members 70 can have the same structure or different structures.

[0458] In some embodiments, the plurality of bus members 70 includes at least one first bus member 70a, which includes a first bus layer 71 and a second bus layer 72 stacked and connected, and the first bus layer 71 is connected to at least two battery cells 10 arranged along the thickness direction X.

[0459] The plurality of bus members 70 can all be the first bus member 70a, or some of them can be the first bus member 70a.

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

[0461] The first bus member 70a has at least a double-layer structure, and both the first bus layer 71 and the second bus layer 72 of the first bus member 70a can transmit current, so that the first bus member 70a has a higher current-carrying area, thereby reducing the heat generation of the first bus member 70a and improving the rapid charging capability of the battery 2.

[0462] Under the premise that the current-carrying area meets the requirements, the first bus member 70a is provided as a double-layer structure, which can reduce the thickness of the first bus layer 71. The battery cell 10 will swell during the cycle process, thereby stretching the first bus layer 71. The first bus layer 71 has a smaller thickness, which is easy to deform to adapt to the deformation of the battery cell 10, reduces the risk of the connection between the battery cell 10 and the first bus layer 71 being pulled apart, and improves the reliability of the battery 2.

[0463] In some embodiments, the battery cell 10 includes an electrode terminal 13 arranged on the shell 12, and the electrode terminal 13 is electrically connected to the electrode assembly 11. The first bus layer 71 is connected to the electrode terminal 13 of the battery cell 10.

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

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

[0466] The second busbar layer 72 can avoid the first busbar layer 71 and the electrode terminal 13 connection, thereby reducing the influence of the second busbar layer 72 on the first busbar layer 71 and the electrode terminal 13 connection when the battery monomer expands, reducing the risk of the electrode terminal 13 and the first busbar layer 71 connection being pulled apart, and improving the reliability of the battery 2. In addition, when assembling the battery monomer 10 and the first busbar component 70a, the second busbar layer 72 does not cover the area of the first busbar layer 71 for connecting with the electrode terminal 13, so that the assembly difficulty can be reduced.

[0467] In some embodiments, the first busbar layer 71 is welded with the electrode terminal 13 and forms a welding mark, and the second busbar layer 72 does not cover the welding mark.

[0468] In some embodiments, the second busbar layer 72 partially overlaps the electrode terminal 13 in the stacking direction of the first busbar layer 71 and the second busbar layer 72, so that the conductive path between the second busbar layer 72 and the electrode terminal 13 can be shortened, thereby reducing the resistance and reducing the heat generation.

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

[0470] In some embodiments, the second busbar layer 72 can be arranged on the side of the first busbar layer 71 facing the battery monomer 10, or on the side of the first busbar layer 71 away from the battery monomer 10.

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

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

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

[0474] In some embodiments, the first busbar layer 71 includes a first busbar portion 711, a second busbar portion 712, and a first buffer portion 713 connecting the first busbar portion 711 and the second busbar portion 712, and the first busbar portion 711 and the second busbar portion 712 are arranged along the thickness direction X and connected to different battery monomers 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 bending portion 73 extends from one end of the first busbar layer 71 along the extension direction Y and bends towards the side away from the battery cell. The bending portion 73 does not cover the side of the first buffer portion 713 along the extension direction Y.

[0477] The first busbar 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 busbar 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 cycle of the battery cell 10, the battery cell 10 expands and exerts a pulling force on the first busbar layer 71; the first buffer portion 713 can release stress by deforming, thereby reducing the stress at the connection between the first busbar portion 711 and the battery cell 10 and the stress at the connection between the second busbar portion 712 and the battery cell 10, and reducing the risk of failure of the connection between the first busbar layer 71 and the battery cell 10. The bending portion 73 is not directly connected to the first buffer portion 713, thereby reducing the influence of the deformation of the bending portion 73 on the first buffer portion 713 and reducing the difficulty of deforming the first buffer portion 713.

[0479] In some embodiments, the first busbar portion 711 is located on the upper side of the electrode terminal 13 of the battery cell 10, and the second busbar portion 712 is located on the upper side of the electrode terminal 13 of the battery cell 10.

[0480] In some embodiments, the first buffer portion 713 comprises an arch-shaped structure.

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

[0482] In some embodiments, the second busbar layer 72 comprises a first laminated portion 721, a second laminated portion 722, and a second buffer portion 723. The first laminated portion 721 is laminated with the first busbar portion 711 and is connected through at least one bending portion 73, and the second laminated portion 722 is laminated with the second busbar portion 712 and is connected through at least one bending portion 73. The second buffer portion 723 connects the first laminated portion 721 and the second laminated portion 722. In the laminating direction of the first busbar layer 71 and the second busbar layer 72, the second buffer portion 723 at least partially overlaps the first buffer portion 713.

[0483] During the cycling process of the battery cell 10, the battery cell 10 expands and applies tension to the first busbar 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 busbar 71 and the battery cell 10. The second buffer portion 723 at least partially overlaps with the first buffer portion 713, so that the deformation areas of the first buffer portion 713 and the second buffer portion 723 are 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 fitted together. Embodiments of this application can save space.

[0485] In some embodiments, the thickness of the first busbar 71 is 1mm-2.5mm. Optionally, the thickness of the first busbar 71 is 1.2mm-1.8mm. As an example, the thickness of the first busbar 71 is 1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, or 2.5mm.

[0486] The thickness of the first busbar 71 is selected based on the expansion pressure of the battery cell 10 in this embodiment, which can balance the current carrying capacity and deformability of the first busbar 71 to a certain extent, thereby improving the fast charging capability and reliability of the battery 2.

[0487] In some embodiments, the thickness of the second bus layer 72 is 1mm-2.5mm. Optionally, the thickness of the second bus layer 72 is 1.2mm-1.8mm. As an example, the thickness of the second bus layer 72 is 1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, or 2.5mm.

[0488] The thickness of the second busbar 72 can be selected based on the thickness of the first busbar 71 and the current carrying capacity of the battery to the first busbar component. For example, when the thickness of the first busbar 71 is small, the second busbar 72 may have a greater thickness than the first busbar 71 to improve the current carrying capacity of the first busbar component.

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

[0490] The expansion of the battery cell 10 is related to the volumetric energy density thereof. The thickness of the first busbar layer 71 is designed according to the volumetric energy density of the battery cell 10, so as to balance the overcurrent capacity of the first busbar layer 71 and the deformability of the first busbar layer 71 to a certain extent, thereby improving the rapid charging capability 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 busbar layer 71 is less than or equal to 2.2 mm.

[0492] The expansion of the battery cell 10 is related to the volumetric energy density thereof. For the battery 2 using the battery cell 10 with high volumetric energy density, the thickness of the first busbar layer 71 needs to be reduced. The thickness of the first busbar layer 71 is designed according to the volumetric energy density of the battery cell 10 in the embodiments of the present application, so as to balance the overcurrent capacity of the first busbar layer 71 and the deformability of the first busbar layer 71 to a certain extent, thereby improving the rapid charging capability 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 in the silicon-based material in the negative electrode active material is 1%-6%, the thickness of the first busbar layer 71 is 1.2 mm-2.2 mm, and the thickness of the second busbar layer 72 is 1.2 mm-2.2 mm.

[0494] For example, the mass content of silicon in the silicon-based material in the negative electrode active material is 1%, 2%, 3%, 4%, 5%, or 6%. For example, the thickness of the first busbar 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. For example, the thickness of the second busbar 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 improved. The introduction of the silicon-based material also increases the expansion of the negative electrode sheet 112 during the cycle process. The thickness of the first busbar layer 71 and the thickness of the second busbar layer 72 are designed in combination with the content of silicon, so as to reduce the risk of connection failure of the first busbar layer 71 and the battery cell 10 caused by the introduction of the silicon-based material, and meet the requirement for the overcurrent capacity of the first busbar component 70a.

[0496] In some embodiments, the first busbar layer 71 includes a first busbar portion 711, a second busbar portion 712, and a first buffer portion 713 connecting the first busbar portion 711 and the second busbar portion 712, the first busbar portion 711 and the second busbar portion 712 are arranged along the thickness direction X and connected to different battery monomers 10. In the stacking direction of the first busbar layer 71 and the second busbar layer 72, the first buffer portion 713 protrudes from the first busbar portion 711 and the second busbar portion 712. The first busbar 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 monomer 10 swells.

[0498] In some embodiments, the volumetric energy density of the battery monomer 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 swelling of the battery monomer 10 is related to its volumetric energy density. According to the volumetric energy density of the battery monomer 10, the depth of the recess 714 is designed, so that the overcurrent capacity of the first buffer portion 713 and the deformability of the first buffer portion 713 are considered to some extent, thereby improving the rapid charging capability and reliability of the battery 2.

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

[0501] The swelling of the battery monomer 10 is related to its volumetric energy density. For the battery 2 using a battery monomer 10 with high volumetric energy density, the difficulty of deforming the first buffer portion 713 needs to be reduced. According to the volumetric energy density of the battery monomer 10, the depth of the recess 714 is designed, so that the overcurrent capacity of the first buffer portion 713 and the deformability of the first buffer portion 713 are considered to some extent, thereby improving the rapid charging capability and reliability of the battery 2.

[0502] FIG. 19 is a top view of a battery according to some embodiments of the present application; FIG. 20 is an enlarged view of the box in FIG. 19; and FIG. 21 is a structural view of a second busbar component in FIG. 20.

[0503] Referring to FIGS. 17-21, in some embodiments, the plurality of busbar components 70 further includes at least one second busbar component 70b, 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 component 70b is greater than the thickness of the second busbar layer 72.

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

[0505] In the battery 2, the expansion amount of the battery cells 10 at different positions can be different. For the battery cells 10 with a smaller 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 is simple in structure, 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 the overcurrent capacity of the second busbar component 70b 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 overcurrent 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 expansion of the plurality of battery cells 10 can be superimposed in the thickness direction X, which causes the displacement of the battery cells 10 adjacent to the limiting beam 21 to be larger; the first busbar component 70a with a double-layer structure is used to connect the battery cells 10 close to the limiting beam 21, which can reduce the risk of connection failure of 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 be connected to two battery cells 10 adjacent in the extension direction.

[0509] In some embodiments, the charging time of the battery cell 10 from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes. As an example, the charging time of the battery cell 10 from 10% state of charge to 80% state of charge is 10.5 min, 10 min, 9.5 min, 9 min, 8.5 min, 8 min, 7.5 min, 7 min, 6.5 min, 6 min, 5.5 min, 5 min, or a range formed by any two of the above values.

[0510] The battery cell 10 of the embodiments of the present application has a fast charging capability, and the charging time can be saved.

[0511] In some embodiments, the charging steps of the battery 2 or any battery cell 10 constituting the battery 2 from 10% to 80% can be performed as follows:

[0512] Charged from 10% SOC to 15% SOC at 5.0C constant current;

[0513] from 20% SOC to 25% SOC at 5.0C constant current;

[0514] from 25% SOC to 30% SOC at 5.0C constant current;

[0515] from 30% SOC to 35% SOC at 5.0C constant current;

[0516] from 35% SOC to 40% SOC at 5.0C constant current;

[0517] from 40% SOC to 45% SOC at 4.6C constant current;

[0518] from 45% SOC to 50% SOC at 4.3C constant current;

[0519] from 50% SOC to 55% SOC at 4.0C constant current;

[0520] from 55% SOC to 60% SOC at 3.7C constant current;

[0521] from 60% SOC to 65% SOC at 3.4C constant current;

[0522] from 65% SOC to 70% SOC at 3.1C constant current;

[0523] from 70% SOC to 75% SOC at 2.9C constant current;

[0524] from 75% SOC to 80% SOC at 2.7C constant current.

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

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

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

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

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

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

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

[0532] charging from 95% SOC to 98% SOC at 0.33C constant current.

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

[0534] In some embodiments, the charging current during the process of charging the battery cell 10 from 10% SOC to 80% SOC can be 2C-6C, alternatively 2.7C-5C. The charging current during the process of charging the battery cell 10 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 for 20 cycles according to the charging strategy and the discharging strategy, the anode sheet of the battery cell 10 is disassembled and the lithium precipitation area of the anode sheet is observed and measured. The ratio of the area of the lithium precipitation area to the total area of the anode sheet is less than 2%.

[0536] As an example, the discharging strategy employs discharging at 0.33C constant current to 2.0V.

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

[0538] charging from 0% SOC to 5% SOC at 5.0C constant current;

[0539] charging from 5% SOC to 10% SOC at 5.0C constant current;

[0540] charging from 10% SOC to 15% SOC at 5.0C constant current;

[0541] charging from 15% SOC to 20% SOC at 5.0C constant current;

[0542] charging from 20% SOC to 25% SOC at 5.0C constant current;

[0543] charging from 25% SOC to 30% SOC at 5.0C constant current;

[0544] charging from 30% SOC to 35% SOC at 5.0C constant current;

[0545] charging from 35% SOC to 40% SOC at 5.0C constant current;

[0546] charging from 40% SOC to 45% SOC at 4.6C constant current;

[0547] charging from 45% SOC to 50% SOC at 4.3C constant current;

[0548] charging from 50% SOC to 55% SOC at 4.0C constant current;

[0549] charging from 55% SOC to 60% SOC at 3.7C constant current;

[0550] charging from 60% SOC to 65% SOC at 3.4C constant current;

[0551] charging from 65% SOC to 70% SOC at 3.1C constant current;

[0552] charging from 70% SOC to 75% SOC at 2.9C constant current;

[0553] charging from 75% SOC to 80% SOC at 2.7C constant current;

[0554] charging from 80% SOC to 85% SOC at 1.8C constant current;

[0555] charging from 85% SOC to 90% SOC at 1.3C constant current;

[0556] charging from 90% SOC to 95% SOC at 0.7C constant current;

[0557] charging from 95% SOC to 98% SOC at 0.33C constant current;

[0558] charging from 98% SOC to 100% SOC at 0.1C constant current.

[0559] The battery cell 10 of the embodiments of the present application can be charged from 10% SOC to 80% SOC within 10.5 minutes without lithium precipitation or with slight lithium precipitation, and has good rapid charging capability. For example, the ratio of the area of the lithium precipitation region to the total area of the negative electrode sheet is less than 0.05% for no lithium precipitation, and the ratio of the area of the lithium precipitation region to the total area of the negative electrode sheet is less than 2% and greater than or equal to 0.05% for slight lithium precipitation.

[0560] According to some embodiments of the present application, the present application also provides a power-using device, comprising the battery 2 of any of the above embodiments, and the battery 2 is used to provide electric energy for the power-using device. The power-using device can be the device or system of any of the above applications of the battery 2.

[0561] Referring to FIGS. 2 to 18, the embodiments of the present application provide a battery 2 including a plurality of battery cells 10, a case 20, a restraint member 40, and a plurality of busbar members 70. The plurality of battery cells 10 are accommodated in the case 20.

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

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

[0564] The negative electrode tab 112 includes a negative electrode current collector 1121 and a negative electrode film layer 1122 provided on at least one side of the negative electrode current collector 1121, the negative electrode film layer 1122 including a negative electrode active material. The negative electrode tab 112 has a porosity of 27% to 40%. The negative electrode film layer 1122 has a packing density of 1.15 g / cm 3 to 1.36 g / cm 3 .

[0565] The negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222 provided between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material provided in the first negative electrode film layer 11221 and a second negative electrode active material provided in the second negative electrode film layer 11222, the first negative electrode active material including artificial graphite, and the second negative electrode active material including one or more of artificial graphite, natural graphite, and a silicon-based material. The first negative electrode active material has a volume average particle diameter Dv50 that is less than or equal to a volume average particle diameter Dv50 of the second negative electrode active material.

[0566] The positive electrode tab 111 includes a positive electrode current collector 1111 and a positive electrode film layer 1112 provided on at least one side of the positive electrode current collector 1111. The positive electrode film layer 1112 has a packing density of 2.50 g / cm 3 to 2.80 g / cm 3 at 100% SOC of the battery cell. The positive electrode tab 111 has a porosity of 25% to 32%. A ratio of a thickness of the positive electrode current collector 1111 to a thickness of the positive electrode film layer 1112 is 0.05 to 0.3. The positive electrode active material includes a lithium-containing phosphate having an olivine structure or a modified material thereof. The positive electrode active material has a volume average particle diameter satisfying 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm.

[0567] The case 20 includes two limiting beams 21 which are arranged at intervals in the thickness direction X of the battery cell 10. The plurality of battery cells 10 are arranged in a plurality of battery cell columns 100 which are arranged in the extension direction Y of the limiting beam 21, and each battery cell column 100 includes at least two battery cells 10 arranged in the thickness direction X of the battery cell 10. The plurality of battery cells 10 are arranged between the two limiting beams 21.

[0568] 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 to have a maximum displacement in the thickness direction X of less than or equal to 8 mm when subjected to a pressure of 1.7 MPa.

[0569] The case 20 includes a frame 22 defining an accommodation space in which the limiting beam 21 and the plurality of battery cells 10 are arranged, and a support beam 23 arranged on a side of the limiting beam 21 facing away from the plurality of battery cells 10 and connecting the frame 22 and the limiting beam 21. A restraint member 40 connects adjacent limiting beams 21 and is bonded to the battery cell 10.

[0570] The plurality of busbar components 70 electrically connect the plurality of battery cells 10. The plurality of busbar components 70 includes at least one first busbar component 70a including a first busbar layer 71 and a second busbar layer 72 which are stacked and connected, and the first busbar layer 71 connects at least two battery cells 10 arranged in the thickness direction X.

[0571] Embodiments

[0572] The following examples are provided to more specifically describe the present application, and are merely illustrative in nature as various modifications and variations will be apparent to those skilled in the art. Unless otherwise stated, all proportions, 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 used as received without further purification, and all instruments used in the examples are commercially available.

[0573] Example 1

[0574] 1. Preparation of positive electrode tab

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

[0576] The positive electrode film layer includes a film layer formed by uniformly coating a positive electrode slurry (solvent: N-methyl pyrrolidone NMP) on the surface of the positive electrode conductive layer, and then drying and cold-pressing.

[0577] The positive electrode active material includes lithium iron phosphate and an ion-conducting layer, the ion-conducting layer is coated on the surface of the lithium iron phosphate, and 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-side coating weight of the positive electrode film layer is 0.21 g / 1540.25 mm 2 , and the compaction density of the positive electrode film layer after cold-pressing is 2.6 g / cm 3 .

[0579] 2. Preparation of the negative electrode sheet

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

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

[0582] The single-side coating weight of the negative electrode film layer is 0.096 g / 1540.25 mm 2 , and the compaction density of the negative electrode film layer after cold-pressing is 1.6 g / cm 3 .

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

[0584] The first negative electrode film layer includes graphite particles, a conductive agent acetylene black, a first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), a negative electrode binder styrene butadiene rubber and a thickening agent sodium carboxymethyl cellulose, the mass content of lithium element in the first lithium-containing binder is 4.8%, the Dv50 of the graphite particles is 11.3 μm, the graphite particles include artificial graphite and a carbon coating layer, the carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0585] The second negative electrode film layer comprises graphite particles, conductive agent acetylene black, a second lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene butadiene rubber and thickening agent sodium carboxymethyl cellulose, the mass content of lithium element in the second lithium-containing binder is 4.8%, the Dv50 of the graphite particles is 11.3 microns, and the graphite particles comprise artificial graphite and a carbon coating layer, the carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0586] 3. Isolation film

[0587] The isolation film comprises a base film, and the base film is a 7-micron polyethylene film layer with a porosity of 42%.

[0588] 4. Preparation of electrolyte

[0589] The electrolyte comprises an organic solvent, a lithium salt and an additive.

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

[0591] The additive has a mass content of 6.5% based on the mass of the electrolyte, and comprises vinylene carbonate VC, fluoroethylene carbonate FEC, ethylene sulfite ES and lithium difluoro(oxalato)borate LiDFOB in a mass ratio of 5:0.5:0.5:0.5.

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

[0593] The electrolyte has an electrical conductivity of 16.4 mS / cm at room temperature.

[0594] 5. Preparation of battery monomer

[0595] The above positive electrode sheet, isolation film and negative electrode sheet are stacked in order, the isolation film is between the positive electrode sheet and the negative electrode sheet to play a separation role, an electrode assembly is obtained, the electrode assembly is placed in a shell, electrolyte is injected after drying, and the battery monomer is obtained through processes such as vacuum packaging, standing, formation and shaping.

[0596] 6. Preparation of battery

[0597] The prepared plurality of battery monomers are installed in the box body and arranged between the two limiting beams, and then the welding bus components are welded, and the high and low voltage wire harnesses are installed to obtain the battery.

[0598] The limiting beam is made of aluminum alloy and has the structure shown in FIG. 12. The limiting beam is located on both sides of the plurality of battery monomers along 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. The included angle a between the first side and the second side of the limiting beam is 5°.

[0599] Example 2

[0600] The battery monomers and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compactness of the negative electrode film layer after cold pressing were adjusted.

[0601] Example 3

[0602] The battery monomers and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compactness of the negative electrode film layer after cold pressing were adjusted.

[0603] Example 4

[0604] The battery monomers and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compactness of the negative electrode film layer after cold pressing were adjusted.

[0605] Example 5

[0606] The battery monomers and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, the compactness of the negative electrode film layer after cold pressing, the included angle a 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.

[0607] Example 6

[0608] The battery monomers and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, the compactness of the negative electrode film layer after cold pressing, the included angle a 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.

[0609] Comparative Example 1

[0610] The battery monomer and battery were prepared by using the similar method of Example 1, and the single-side coating weight of the positive electrode film layer, the single-side coating weight of the negative electrode film layer, and the compactness of the negative electrode film layer after cold pressing were adjusted.

[0611] Comparative Example 2

[0612] The battery monomer and battery were prepared by using the similar method of Example 1, and the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compactness of the negative electrode film layer after cold pressing were adjusted.

[0613] Comparative Example 3

[0614] The battery monomer and battery were prepared by using the similar method of Example 1, and the single-side coating weight of the positive electrode film layer, the compactness of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, the compactness of the negative electrode film layer after cold pressing, the included angle a of 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.

[0615] Performance test

[0616] 1. Test the swelling pressure of the battery monomer:

[0617] At an ambient temperature of 45°C, the battery monomer prepared above was discharged to 2.0V at a constant current discharge rate of 1C;

[0618] The battery monomer was clamped between two clamping plates, wherein the two clamping plates were located on both sides of the battery monomer along the thickness direction and covered the large surface;

[0619] At an ambient temperature of 45°C, the battery monomer was charged to 3.8V at a constant current charge rate of 0.8C, and the pressure exerted by the battery monomer on the clamping plate was detected and recorded;

[0620] The battery monomer was subjected to cyclic charging and discharging according to the above charging strategy and the charging strategy until the battery monomer decayed to 70% SOH (the discharge capacity of the battery monomer decayed to 70% of the nominal capacity of the battery monomer), and the maximum pressure exerted by the battery monomer on the clamping plate was recorded;

[0621] The swelling pressure Q of the battery monomer in the thickness direction was calculated as: maximum pressure / large surface area.

[0622] 2. Test the maximum displacement E of the first side of the limiting beam in the thickness direction under a pressure of 1.7MPa.

[0623] The box was fixed to the fixture;

[0624] The pressure head of the pressure testing machine is abutted against the first side surface 21a of the limiting beam, wherein the pressure surface of the pressure head abutted against the first side surface 21a is the same as the large surface of the battery monomer;

[0625] A constant force F is applied to the pressure head, and the pressure head is moved along the thickness direction X of the battery monomer 10, and the maximum displacement E of the pressure head is recorded. Exemplarily, the area of the pressure surface is S, and F / S is 1.7 MPa.

[0626] It is explained here that the maximum displacement E is detected as the box and the box for mounting the battery monomer are the same box.

[0627] 3. Volume energy density test:

[0628] The first week discharge energy is tested according to the following steps: at 25℃, the battery monomer prepared above is charged to 3.8V at 0.33C constant current, and then discharged to 2.0V at 0.33C constant current, and the discharge energy A0 at this time is recorded, unit: Wh.

[0629] The volume of the battery monomer: the length, width and height of the battery monomer are measured using a caliper (generally calculated based on the size of the shell of the battery monomer, excluding the height of the electrode terminal, and excluding the insulating film outside the shell), and the volume V0 of the battery monomer is calculated, unit L.

[0630] The volume energy density VED of the battery monomer is A0 / V0, unit Wh / L.

[0631] 4. Cycle performance test one:

[0632] At an ambient temperature of 45℃, the battery prepared above is discharged, and the battery monomer is discharged to 2.0V at a constant current discharge rate of 1C;

[0633] At an ambient temperature of 45℃, the battery prepared above is charged, and the battery monomer is charged to 3.8V at a constant current charge rate of 0.8C;

[0634] The battery is cycled according to the above charging strategy and charging strategy until the battery shows cycle diving or decays to 70% SOH (discharge capacity of the battery / nominal capacity of the battery = 70%).

[0635] 5. Cycle performance test two:

[0636] At an ambient temperature of 30℃, the battery prepared above is discharged, and the battery monomer is discharged to 2.0V at 0.33C;

[0637] At an ambient temperature of 30℃, the battery is charged using the following charging strategy:

[0638] Charged from 0% SOC to 5% SOC at a constant current of 5.0C;

[0639] Charge from 5% SOC to 10% SOC at 5.0C constant current;

[0640] Charge from 10% SOC to 15% SOC at 5.0C constant current;

[0641] Charge from 15% SOC to 20% SOC at 5.0C constant current;

[0642] Charge from 20% SOC to 25% SOC at 5.0C constant current;

[0643] Charge from 25% SOC to 30% SOC at 5.0C constant current;

[0644] Charge from 30% SOC to 35% SOC at 5.0C constant current;

[0645] Charge from 35% SOC to 40% SOC at 5.0C constant current;

[0646] Charge from 40% SOC to 45% SOC at 4.6C constant current;

[0647] Charge from 45% SOC to 50% SOC at 4.3C constant current;

[0648] Charge from 50% SOC to 55% SOC at 4.0C constant current;

[0649] Charge from 55% SOC to 60% SOC at 3.7C constant current;

[0650] Charge from 60% SOC to 65% SOC at 3.4C constant current;

[0651] Charge from 65% SOC to 70% SOC at 3.1C constant current;

[0652] Charge from 70% SOC to 75% SOC at 2.9C constant current;

[0653] Charge from 75% SOC to 80% SOC at 2.7C constant current;

[0654] Charge from 80% SOC to 85% SOC at 1.8C constant current;

[0655] Charge from 85% SOC to 90% SOC at 1.3C constant current;

[0656] Charge from 90% SOC to 95% SOC at 0.7C constant current;

[0657] Charge from 95% SOC to 98% SOC at 0.33C constant current;

[0658] Charge from 98% SOC to 100% SOC at 0.1C constant current.

[0659] The battery is cycled according to the above charging strategy and the charging strategy until the battery appears cycle diving or decays to 70% SOH.

[0660] It is explained that cycle performance test one and cycle performance test two are respectively tests on two batteries prepared by the same preparation method.

[0661] The test results of examples 1-5 and comparative examples 1-3 are shown in table 1.

[0662] Referring to table 1, the single-side coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing of the positive electrode film layer of comparative example 1 are low, although the battery monomer has a small expansion pressure, and is not prone to cycle diving in the process of cycling, but the volumetric energy density of the battery monomer is low.

[0663] Referring to examples 1-5 and comparative examples 1-3, the single-side coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing of the positive electrode film layer of the present application can be increased, so that the volumetric energy density of the battery monomer is greater than or equal to 390 Wh / L. Although the expansion pressure of the battery monomer is not less than 0.5 MPa, but combined with the limiting beam with high anti-deformation ability, the expansion of the battery monomer can be effectively limited to improve the cycle performance of the battery and the battery monomer, and reduce the risk of battery cycle diving.

[0664] Referring to examples 1-5 and comparative example 2, by adjusting the single-side coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-side coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing, the expansion pressure of the battery monomer can be limited to not more than 2.4 MPa, and the volumetric energy density of the battery monomer can reach 415 Wh / L. The limiting beam with high anti-deformation ability can effectively limit the expansion of the battery monomer to improve the cycle performance of the battery and the battery monomer, and reduce the risk of battery cycle diving.

[0665] 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 adjusting 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 constrain and limit the expansion of the battery monomer when the expansion pressure of the battery monomer reaches 2.4 MP, so as to improve the cycle performance of the battery and the battery monomer, and reduce the risk of battery cycle diving.

[0666] Referring to Table 1, in the process of fast charging of the battery, the embodiments of the present application can limit the deformation of the battery monomer, reduce the risk of battery cycle diving, and improve the cycle performance of the battery and the battery monomer. The battery monomer has the ability of fast charging, and the charging time of the battery monomer from 10% SOC to 80% SOC can be 5 minutes to 10.5 minutes.

[0667] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0668] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

A battery comprising: Multiple battery cells are arranged along the thickness direction of the battery cells, and each battery cell includes a housing and an electrode assembly housed within the housing; as well as, A housing for accommodating the plurality of battery cells, the housing including at least two limiting beams, with adjacent limiting beams respectively disposed 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 0.5MPa-2.4MPa, and the limiting beam includes a first side facing the plurality of battery cells. The first side is configured such that, under a pressure of 1.7MPa, the maximum displacement of the first side in the thickness direction is less than or equal to 8mm. According to claim 1, wherein, The expansion pressure of the battery cell in the thickness direction is 1.5MPa-2.0MPa. The battery according to claim 1 or 2, wherein, The electrode assembly includes two first surfaces and two second surfaces. The two first surfaces are disposed opposite to each other along the thickness direction, and the two second surfaces are disposed opposite to each other along a direction perpendicular to the thickness direction. The second surfaces are connected to the two first surfaces. The area of ​​the first surface is greater than the area of ​​the second surface. The battery according to claim 3, wherein, The first surface is parallel to the first side surface. The battery according to any one of claims 1-4, 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 including a negative electrode active material. According to claim 5, wherein, The single-sided coating weight of the negative electrode film is 90 mg / 1540 mm². 2 Up to 170mg / 1540mm 2 110mg / 1540mm is available as an option. 2 Up to 150mg / 1540mm 2 . The battery according to claim 5 or 6, wherein, The compaction density of the negative electrode film at 100% SOC of the battery cell is 1.15 g / cm³. 3 Up to 1.36 g / cm 3 The option is 1.25g / cm³. 3 Up to 1.36 g / cm 3 . The battery according to any one of claims 5-7, wherein, The porosity of the negative electrode is 27%-40%. The battery according to any one of claims 5-8, wherein, The negative electrode active material includes at least one of artificial graphite and natural graphite. The battery according to any one of claims 5-9, wherein, The negative electrode active material includes a silicon-based material, wherein the silicon element in the silicon-based material has a mass content of 0.3% to 10%, optionally 1% to 6%. The battery according to claim 10, wherein, The silicon-based material includes at least one of silicon oxide compounds and silicon-carbon composites. The battery according to any one of claims 5-11, wherein, The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the second negative electrode film layer is disposed between the first negative electrode film layer and the negative electrode current collector; The negative electrode active material includes a first negative electrode active material disposed on the first negative electrode film layer and a second negative electrode active material disposed on the second negative electrode film layer. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials. The battery according to claim 12, wherein, The thickness ratio of the first negative electrode film layer to the thickness of the second negative electrode film layer is 3:7 to 7:3, and can be selected as 4:6 to 6:

4. The battery according to claim 12 or 13, wherein, The thickness of the first negative electrode film is less than or equal to the thickness of the second negative electrode film. The battery according to any one of claims 12-14, wherein, The volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material. The battery according to any one of claims 12-15, wherein, The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and can be selected as 7.8 μm-11.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5μm-18.5μm, and can be selected as 9.5μm-14.6μm. The battery according to any one of claims 5-16, wherein, The specific surface area of ​​the negative electrode active material is 0.5 m². 2 / g-3m 2 / g, optional 0.6m 2 / g-1.2m 2 / g. The battery according to any one of claims 1-17, wherein, The electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector, the positive electrode film layer includes a positive electrode active material, the positive electrode active material being a lithium-containing phosphate. The battery according to claim 18, wherein, The single-sided coating weight of the positive electrode film is 200 mg / 1540 mm². 2 -370mg / 1540 / mm 2 ; 240mg / 1540mg is optional 2 Up to 330mg / 1540mm 2 . The battery according to claim 18 or 19, wherein, The compaction density of the positive electrode film at 100% SOC of the battery cell is 2.50 g / cm³. 3 Up to 2.80 g / cm 3 ; 2.55g / cm³ is optional 3 -2.70g / cm 3 . The battery according to any one of claims 18-20, wherein, The porosity of the positive electrode is 25%-32%. The battery according to any one of claims 18-21, wherein, The thickness of the positive electrode sheet is 0.13mm-0.2mm. The battery according to any one of claims 18-22, wherein, The ratio of the thickness of the positive current collector to the thickness of the positive electrode film is 0.05-0.

3. The battery according to any one of claims 18-23, wherein, The volume average particle size of the positive electrode active material satisfies 1μm≤Dv50≤2μm and 0.4μm≤Dv10≤0.7μm. The battery according to any one of claims 1-24, wherein, The battery cell includes an electrolyte contained within the casing. The battery according to claim 25, wherein, The electrolyte has a conductivity of 15 mS / cm to 20 mS / cm at room temperature. The battery according to claim 25 or 26, wherein, The electrolyte includes an organic solvent, which includes one or more of carbonate solvents and carboxylic acid ester solvents. The battery according to claim 27, wherein, The carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. The battery according to claim 27 or 28, wherein, The carboxylic acid ester comprises R1-COO-R2, wherein R1 and R2 each independently comprise an alkyl group having 1-5 carbon atoms or a haloalkyl group having 1-5 carbon atoms. The battery according to any one of claims 25-29, wherein, The electrolyte includes a lithium salt, the lithium salt... The salts include lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is from 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) is from 0.5 mol / L to 1.0 mol / L. The battery according to any one of claims 25-30, wherein, The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL. The battery according to any one of claims 1-31, wherein, The electrode assembly includes a negative electrode sheet; the dimension of the electrode assembly along 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. The battery according to any one of claims 1-32, wherein, The distance between two adjacent limiting beams in the thickness direction is D1; Multiple battery cell rows are arranged between adjacent limiting beams, the multiple battery cell rows are arranged in a direction perpendicular to the thickness direction, and each battery cell row includes at least two battery cells arranged in the thickness direction; The total dimension of the electrode assembly of the battery cell in the battery cell array in the thickness direction is D2; 85% ≤ D2 / D1 ≤ 92%. The battery according to any one of claims 1-33, wherein, The limiting beam includes a second side, which is located on the side of the limiting beam away from the plurality of battery cells and is inclined toward the first side. The battery according to claim 34, wherein, The angle α between the first side and the second side is 1°-25°. The battery according to claim 34 or 35, wherein, The volumetric energy density of the battery cell is 390Wh / L-450Wh / L, and the angle α between the first side and the second side is 5°-20°. The battery according to claim 34 or 35, wherein, The volumetric energy density of the battery cell is 450Wh / L-480Wh / L, and the angle α between the first side and the second side is 8°-25°. The battery according to any one of claims 34-37, 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, the negative electrode active material includes at least one of silicon oxide compound and silicon-carbon composite; The angle α between the first side and the second side is 8°-25°. The battery according to any one of claims 34-38, wherein, The limiting beam includes a third side, which is located on the side of the limiting beam away from the battery cell and parallel to the first side, and the third side is connected to the second side. The battery according to any one of claims 1-39, wherein, The housing includes a frame and a support beam. The frame defines an accommodating space, and the limiting beam and the plurality of battery cells are disposed in the accommodating space. The support beam is located on the side of the limiting beam opposite to the plurality of battery cells and connects the frame and the limiting beam. The battery according to claim 40, wherein, The limiting beam extends in a direction perpendicular to the thickness direction; The housing includes a plurality of support beams spaced apart along the extension direction of the limiting beam. The battery according to claim 40 or 41, wherein, The limiting beam also includes a second side and a third side. The third side is located on the side of the limiting beam away from the battery cell and is parallel to the first side. The second side is connected to one end of the third side and is inclined toward the first side. The support beam is connected to the third side surface. The battery according to any one of claims 1-42, wherein, The limiting beam includes an outer wall and multiple reinforcing ribs. The outer wall encloses a receiving cavity, and the multiple reinforcing ribs are disposed in the receiving cavity and connected to the outer wall. The outer wall includes the first side surface. The battery according to claim 43, 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 silicon-based material contains 1%-6% silicon by mass in the negative electrode active material; the outer wall has a thickness of 2mm-7mm, and the reinforcing rib has a thickness of 2mm-7mm. The battery according to claim 43 or 44, wherein, The outer wall includes a first sidewall and a second sidewall spaced apart along the thickness direction, the second sidewall being located on the side of the first sidewall away from the battery cell, and the first sidewall including the first side surface; The plurality of reinforcing ribs includes a first reinforcing rib connected to the first sidewall. The battery according to claim 45, wherein, At least one of the first reinforcing ribs is inclined relative to the thickness direction. The battery according to claim 46, wherein, The limiting beam extends in a direction perpendicular to the thickness direction; At least two of the first reinforcing ribs are spaced apart along a direction perpendicular to both the extension direction and the thickness direction of the limiting beam, and are inclined in the opposite direction to the thickness direction. The battery according to claim 46 or 47, wherein, The angle between the first reinforcing rib and the thickness direction is 30°-80°. The battery according to any one of claims 45-48, wherein, The first sidewall includes a central region and two edge regions. In a direction parallel to the first sidewall and perpendicular to the extension direction of the limiting beam, the two edge regions extend from both ends of the central region, and the central region and the edge regions are of equal size. At least one of the first reinforcing ribs is connected to the central region. The battery according to any one of claims 45-49, wherein, The outer wall includes a first sidewall and a second sidewall spaced apart along the thickness direction, the second sidewall being located on the side of the first sidewall away from the plurality of battery cells, and the first sidewall including the first side surface; The second sidewall includes a first segment and a second segment, the first segment being parallel to the first sidewall, and the second segment extending from one end of the first segment and inclined toward the first sidewall; At least one of the reinforcing ribs is connected at the junction of the first segment and the second segment. The battery according to any one of claims 43-50, wherein, 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. One sidewall includes the first sidewall; The limiting beam also 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 sidewall and the partition wall, and at least one of the reinforcing ribs connects the second sidewall and the partition wall. The battery according to any one of claims 43-51, wherein, The limiting beam is a one-piece molded structure. The battery according to any one of claims 1-52 further includes an insulating member disposed between the limiting beam and the outer casing. The battery according to any one of claims 1-53 further includes a constraint member connected to an adjacent limiting beam. The battery according to claim 54, wherein, The constraint is connected to the battery cell. The battery according to claim 55, wherein, The constraint member is bonded to the battery cell. The battery according to any one of claims 54-56, wherein, The constraint member is detachably connected to the limiting beam. The battery according to any one of claims 54-57 further includes a fixing member connecting the constraint member and the limiting beam, wherein at least a portion of the fixing member is embedded in and fixed to the limiting beam. The battery according to claim 58, wherein, The limiting beam has a receiving cavity inside, and the fixing member is received in the receiving cavity. The battery according to any one of claims 54-59, wherein, The limiting beam extends in a direction perpendicular to the thickness direction; There are multiple constraint members, and the multiple constraint members are spaced apart along the extension direction of the limiting beam. The battery according to any one of claims 1-60, wherein, The battery also includes multiple busbar components that electrically connect the multiple battery cells; The plurality of busbar components include at least one first busbar component, the first busbar component including a first busbar layer and a second busbar layer stacked and connected, the first busbar layer connecting at least two of the battery cells arranged along the thickness direction. The battery according to claim 61, wherein, The battery cell includes electrode terminals disposed on the housing, and the electrode terminals are electrically connected to the electrode assembly; The portion of the first bus layer that does not overlap with the second bus layer is connected to the electrode terminal. The battery according to claim 61 or 62, wherein, The first busbar component includes at least one bend, which connects the first busbar layer and the second busbar layer. The battery according to claim 63, wherein, The first busbar layer includes a first busbar section, a second busbar section, and a first buffer section connecting the first busbar section and the second busbar section. The first busbar section and the second busbar section are disposed along the thickness direction and connected to different battery cells. The bent portion is positioned to avoid the first buffer portion. The battery according to claim 64, wherein, The second busbar includes a first stacked portion, a second stacked portion, and a second buffer portion. The first stacked portion is stacked with the first busbar and connected to it through at least one of the bending portions. The second stacked portion is stacked with the second busbar and connected to it through at least one of the bending portions. The second buffer section connects the first stacked section and the second stacked section; In the stacking direction of the first busbar layer and the second busbar layer, the second buffer portion overlaps at least partially with the first buffer portion. The battery according to claim 65, wherein, The second buffer part and the first buffer part are fitted together. The battery according to any one of claims 61-66, wherein, The plurality of busbar components further includes at least one second busbar component, the thickness of which is greater than the thickness of the first busbar layer, and the thickness of the second busbar component is greater than the thickness of the second busbar layer. The battery according to claim 67, wherein, The sum of the thickness of the first busbar layer and the thickness of the second busbar layer is equal to the thickness of the second busbar component. The battery according to any one of claims 61-68, wherein, The battery cell adjacent to the limiting beam is connected to the first busbar component. The battery according to any one of claims 61-69, wherein, The thickness of the first busbar layer is 1mm-2.5mm; and / or the thickness of the second busbar layer is 1mm-2.5mm. The battery according to any one of claims 61-70, wherein, The volumetric energy density of the battery cell is 390Wh / L-450Wh / L, and the thickness of the first busbar is less than or equal to 2.5mm; or, The volumetric energy density of the battery cell is 450Wh / L-480Wh / L, and the thickness of the first busbar is less than or equal to 2.2mm. The battery according to any one of claims 61-71, 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 silicon-based material contains 1%-6% silicon by mass in the negative electrode active material; the thickness of the first busbar layer is 1.2mm-2.2mm, and the thickness of the second busbar layer is 1.2mm-2.2mm. The battery according to any one of claims 61-72, wherein, The first busbar layer includes a first busbar section, a second busbar section, and a first buffer section connecting the first busbar section and the second busbar section. The first busbar section and the second busbar section are disposed along the thickness direction and connected to different battery cells. In the stacking direction of the first busbar layer and the second busbar layer, the first buffer portion protrudes from the first busbar portion and the second busbar portion; The first busbar layer has a recess at a position corresponding to the first buffer section. The battery according to claim 73, wherein, The volumetric energy density of the battery cell is 390Wh / L-450Wh / L, and the depth of the recess is 1.2mm-2.5mm; or, The volumetric energy density of the battery cell is 450Wh / L-480Wh / L, and the depth of the recess is 1mm-2.2mm. The battery according to any one of claims 1-74, wherein, The charging time for a single battery cell from 10% SOC to 80% SOC is 5 to 10.5 minutes. An electrical device, characterized in that, Includes a battery according to any one of claims 1-75, the battery being used to provide electrical energy.

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