Battery and electric device

Abstract

A battery (2) and an electrical device. The battery (2) comprises a box body (20) and a battery cell (10). The box body (20) comprises a first box wall (21). The battery cell (10) is accommodated in the box body (20) and located on the lower side of the first box wall (21), the battery cell (10) comprises a shell (12), an electrode assembly (11) and a pressure relief mechanism (15), the shell (12) is fixed to the first box wall (21), the electrode assembly (11) is accommodated in the shell (12), the shell (12) comprises a first end wall (12a), the first end wall (12a) is located on the side, away from the first box wall (21), of the electrode assembly (11), and the pressure relief mechanism (15) is arranged on the first end wall (12a). At room temperature, the charging time of the battery cell (10) from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes.

Description

Battery and powered device TECHNICAL FIELD

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

[0002] Batteries are widely used in electronic devices, such as mobile phones, notebook computers, electric cars, electric vehicles, electric aircraft, electric ships, electric toy cars, electric toy ships, electric toy aircraft, 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 powered device, which can improve the reliability.

[0006] In a first aspect, an embodiment of the present application provides a battery, which includes a box body and a battery monomer. The box body includes a first box wall. The battery monomer is contained in the box body and located at the lower side of the first box wall. The battery monomer includes an outer shell, an electrode assembly, and a pressure relief mechanism. The outer shell is fixed to the first box wall. The electrode assembly is contained in the outer shell. The outer shell includes a first end wall, which is located at the side of the electrode assembly away from the first box wall. The pressure relief mechanism is arranged on the first end wall. The charging time of the battery monomer from 10% SOC to 80% SOC under room temperature conditions is 5 minutes to 10.5 minutes.

[0007] The battery monomer has a fast charging capability, which can save charging time and improve user experience. During the fast charging process of the battery, even if the battery monomer is accidentally in thermal runaway, the high-temperature substances generated by the battery monomer can be sprayed downward through the pressure relief mechanism, thereby reducing the thermal impact on the upper side of the battery, reducing the risk of user injury, and improving the reliability of the battery and the powered device using the battery.

[0008] In some embodiments, the pressure relief mechanism and the first end wall are an integrally formed structure. Integrally forming the pressure relief mechanism and the first end wall can save the space required for connecting the pressure relief mechanism and the first end wall, provide more space for the pressure relief mechanism, improve the pressure relief efficiency, and improve the reliability of the battery.

[0009] In some embodiments, the battery further includes a heat exchange member for heat exchange with the outer shell. During the charging process of the battery, the heat exchange member can exchange heat with the outer shell of the battery monomer, thereby controlling the temperature of the battery monomer within a suitable range, improving the cycle performance of the battery monomer, reducing the risk of thermal runaway, and improving the reliability.

[0010] In some embodiments, the shell further comprises a second end wall and a side wall, the first end wall is opposite to the second end wall, and the side wall connects the first end wall and the second end wall and surrounds the electrode assembly, and the second end wall is fixed to the first box wall. The heat exchange member is arranged on the side wall. The pressure relief mechanism is arranged on the first end wall, and the second end wall is fixed to the first box wall. Arranging the heat exchange member on the side wall can reduce the risk of interference between the heat exchange member and the pressure relief mechanism and save space in the vertical direction.

[0011] In some embodiments, the side wall comprises two first side walls and two second side walls, the two first side walls are arranged opposite to each other along the thickness direction of the battery cell, the two second side walls are arranged opposite to each other along a first direction perpendicular to the thickness direction, and each second side wall connects the two first side walls. At least one first side wall of the battery cell is connected with the heat exchange member. The first side wall is the largest shell wall of the shell. Connecting the first side wall with the heat exchange member can increase the heat exchange area, improve the heat exchange efficiency, thereby reducing the temperature rise of the battery cell during fast charging, reducing the risk of thermal runaway, and improving the reliability.

[0012] 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 between the positive electrode current collectors, the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium-containing phosphate with an olivine structure. One first side wall of the battery cell is connected with the heat exchange member.

[0013] The lithium-containing phosphate with an olivine structure has excellent cycle stability. Using the lithium-containing phosphate with an olivine structure can reduce the heat generation of the battery cell during fast charging and reduce the risk of thermal runaway of the battery cell. Using the lithium-containing phosphate with an olivine structure can reduce the heat exchange demand. The embodiments of the present application only connect one side first side wall of the battery cell with the heat exchange member, which can reduce the number of heat exchange members, save space, and improve the energy density of the battery.

[0014] In some embodiments, the battery comprises a plurality of battery cell groups and a plurality of heat exchange members, the plurality of battery cell groups are arranged along the thickness direction, and each battery cell group comprises at least two battery cells arranged along a first direction. One heat exchange member is arranged between every two battery cell groups. One heat exchange member can exchange heat with the battery cells of two battery cell groups at the same time, which can reduce the number of heat exchange members and improve the space utilization and energy density of the battery.

[0015] In some embodiments, the heat exchange member is bonded to the first side wall through a first adhesive layer. The first adhesive layer can stably connect the heat exchange member with the first side wall to improve the stability of heat exchange between the heat exchange member and the battery cell.

[0016] In some embodiments, the heat exchange member comprises a heat conduction plate, and the heat conduction plate is internally provided with a flow channel for the flow of a heat exchange medium. The heat exchange medium exchanges heat with the battery cell when flowing through the heat conduction plate.

[0017] In some embodiments, the heat exchange member further comprises an insulation layer disposed on the outer surface of the heat conduction plate and configured to separate the heat conduction plate from the first side wall. The insulation layer can insulate the heat conduction plate from the first side wall, increase the creepage distance between the heat conduction plate and the first side wall, and reduce the risk of short circuit.

[0018] In some embodiments, the thermal conductivity of the insulation layer is greater than or equal to 0.1 W / (m·K). The insulation layer has good heat conduction capacity, thereby improving the heat exchange efficiency.

[0019] In some embodiments, the shell is bonded to the first box wall by a second adhesive layer. The second adhesive layer can fix the battery monomer to the first box wall, thereby improving the stability of the battery monomer. The second adhesive layer is easy to form, which is conducive to simplifying the assembly process.

[0020] In some embodiments, the battery monomer further comprises a first electrode terminal disposed on the first end wall, and the electrode assembly comprises an electrode body and a first tab extending from the electrode body, and the first electrode terminal is electrically connected to the first tab. By disposing the first electrode terminal on the first end wall, the space below the battery monomer can be fully utilized, the risk of interference of the first electrode terminal with the connection of the shell and the first box wall is reduced, and the space utilization is improved.

[0021] In some embodiments, the area of the projection of the part of the first electrode terminal located outside the first end wall on the first end wall is 200mm 2 -600mm 2 . The part of the first electrode terminal located outside the first end wall has a larger area, which can increase the overcurrent area, reduce heat generation, reduce the temperature rise of the first electrode terminal during battery cycling, and improve reliability. The first electrode terminal has a larger exposed area, which can increase the heat dissipation efficiency of the first electrode terminal.

[0022] In some embodiments, the first end wall has an inner surface facing the electrode assembly, and the first electrode terminal does not exceed the inner surface in the direction close to the electrode assembly. The first electrode terminal can not occupy the internal space of the shell, thereby improving the space utilization of the battery monomer and improving the energy density of the battery monomer.

[0023] In some embodiments, the first electrode terminal comprises a connecting portion provided with a through hole, the first tab is arranged in the through hole, and a part of the first tab is located on the side of the connecting portion away from the electrode body and connected to the connecting portion. By providing the through hole, the first tab can be led out to the outside of the connecting portion, thereby reducing the distance between the connecting portion and the electrode body, improving the internal space utilization of the battery monomer, and improving the energy density of the battery monomer.

[0024] In some embodiments, the first electrode terminal includes a terminal body and a cover plate, the terminal body is fixed to the first end wall, the terminal body is provided with a recess on a side away from the electrode body, and a bottom wall of the recess is a connecting portion. The cover plate is arranged on a side of the connecting portion away from the electrode body and is used for covering the recess. The recess can accommodate a part of the first tab, thereby improving the space utilization. The cover plate separates the external space of the shell from the through hole, thereby achieving sealing and reducing the risk of electrolyte leakage.

[0025] In some embodiments, at least part of the cover plate is accommodated in the recess. By accommodating the cover plate in the recess, the space utilization can be improved.

[0026] In some embodiments, in the width direction of the first end wall, the size of the first end wall is W1 mm, and the size of the part of the first electrode terminal outside the first end wall is W2 mm. W2 and W1 satisfy: 0.4≤W2 / W1≤1.

[0027] By setting W2 / W1 to be greater than or equal to 0.4, the first electrode terminal can have a larger exposed area, the connection area between the first electrode terminal and the current collecting component can be increased, the overcurrent capacity can be improved, the temperature rise can be reduced, the cycle performance of the battery can be improved, and the reliability of the battery can be improved. By limiting W2 / W1 to be less than or equal to 1, the space occupied by the first electrode terminal in the width direction can be reduced, and the space utilization can be improved.

[0028] In some embodiments, the box body further includes a second box wall arranged on the lower side of the battery monomer and arranged opposite to the first box wall. The second box wall can protect the battery monomer from the lower side to reduce the risk of the battery monomer being impacted by external impurities and improve the reliability of the battery.

[0029] In some embodiments, the second box wall is arranged spaced apart from the battery monomer. When the battery monomer is in thermal runaway, the space between the second box wall and the battery monomer can serve as a discharge channel to timely discharge the substances released by the battery monomer to the outside of the box body, thereby reducing the risk of explosion of the battery. When the second box wall is impacted by external impact, the space between the second box wall and the battery monomer can play a blocking role to reduce the impact force transmitted to the battery monomer, thereby reducing the risk of failure of the battery monomer and improving the reliability of the battery.

[0030] In some embodiments, the battery further includes a support arranged on the lower side of the first end wall and used for supporting the first end wall. The support can support the battery monomer, thereby improving the stability of the battery monomer and improving the structural strength of the entire battery.

[0031] In some embodiments, the box body further includes a second box wall arranged on the lower side of the battery monomer and arranged opposite to the first box wall. The support is bonded to the first end wall and the second box wall. The support connects the battery monomer and the second box wall, thereby improving the structural strength of the entire battery.

[0032] In some embodiments, the elastic modulus of the support is less than the elastic modulus of the second box wall. The support has a smaller elastic modulus, and when the second box wall is subjected to an external impact, the support can deform to reduce the force transmitted to the battery cells, thereby reducing the risk of failure of the battery cells.

[0033] In some embodiments, the battery further comprises a plurality of limiting beams connected to the first box wall, the plurality of limiting beams being spaced apart along the thickness direction of the battery cells, and a plurality of battery cells being arranged between adjacent limiting beams. The support is connected to the adjacent limiting beams.

[0034] The limiting beam has a high deformation resistance and can effectively constrain the battery cells in the thickness direction; the support can provide a restraining force to the limiting beam, thereby reducing the deformation of the limiting beam and limiting the expansion of the battery cells, improving the cycle performance of the battery cells, and reducing the risk of cracking of the battery box.

[0035] In some embodiments, the support comprises a metal strip and an insulating film covering the metal strip, and the insulating film separates the metal strip from the first end wall. The metal strip has high strength and can effectively constrain the limiting beam. The insulating film can insulate and separate the metal strip from the battery cells, thereby reducing the risk of short circuit.

[0036] In some embodiments, the support has a cavity inside. By providing a cavity, the weight of the support can be reduced.

[0037] In some embodiments, the first box wall is used as at least part of the floor of the vehicle. Using the first box wall as the floor can save vehicle parts, improve the integration of the vehicle, and simplify the assembly process of the vehicle.

[0038] In some embodiments, the battery further comprises a mounting beam arranged on the side of the first box wall away from the battery cells. The mounting beam is connected to the first box wall, which can improve the overall strength of the battery. The mounting beam can also provide mounting positions for some components of the electric device, thereby reducing the number of parts, improving integration, and simplifying the assembly process.

[0039] In some embodiments, the mounting beam is used to mount the seat of the vehicle. Combining the mounting beam for mounting the seat with the first box wall can improve the utilization rate of the vehicle.

[0040] In some embodiments, the battery cell further comprises a sampling member arranged in the shell, and the sampling member is used to collect the temperature of the shell. The sampling member can collect the temperature of the shell in real time, so as to monitor and adjust the temperature of the battery cell, reduce the risk of abnormal temperature rise of the battery cell during rapid charging, and improve the reliability of the battery.

[0041] In some embodiments, the battery cell has an expansion pressure in the thickness direction of 0.5 MPa to 2.4 MPa. Limiting the expansion pressure of the battery cell in the thickness direction to 0.5 MPa to 2.4 MPa reduces the deformation of the battery cell during rapid charging, improves the cycle performance of the battery cell, reduces the risk of cracking of the battery case, and improves the reliability of the battery.

[0042] In some embodiments, the battery includes a plurality of battery cells and 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 electrically connecting at least two battery cells arranged in the thickness direction.

[0043] The first busbar component has at least a double-layer structure, and the first busbar layer and the second busbar layer of the first busbar component can both transmit current, so that the first busbar component has a high current-carrying area, thereby reducing heat generation of the first busbar component, improving the rapid charging capability of the battery, and reducing the risk of thermal runaway. Under the premise that the current-carrying area meets the requirements, the first busbar component is set to a double-layer structure, which can reduce the requirement for the thickness of the first busbar layer. The battery cell will expand during the cycle, thereby stretching the first busbar layer. The first busbar layer has a small thickness and is easily deformed to adapt to the deformation of the battery cell, thereby reducing the risk of the connection between the battery cell and the first busbar layer being pulled apart and improving the reliability of the battery.

[0044] 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 current-carrying capability of the first busbar component.

[0045] 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 in the thickness direction and connected to different battery cells. The second busbar layer includes a first stacking portion, a second stacking portion, and a second buffer portion, the first stacking portion being stacked with the first busbar portion and connected by at least one bending portion, the second stacking portion being stacked with the second busbar portion and connected by at least one bending portion, and the second buffer portion connecting the first stacking portion and the second stacking portion.

[0046] In the circulation process of the battery, part of the current can be transmitted between the first busbar and the second busbar through the first laminated part, the second buffer part and the second laminated part, a plurality of conductive paths are formed between the first busbar and the second busbar, thereby improving the overcurrent capacity. In the circulation process of the battery cell, the battery cell expands and exerts a pulling force on the first busbar layer; both the first buffer part and the second buffer part can release stress by deformation, thereby reducing the risk of connection failure of the first busbar layer and the battery cell.

[0047] In some embodiments, the box further comprises a plurality of limiting beams connected to the first box wall, the plurality of limiting beams are arranged in the thickness direction of the battery cell, and a plurality of battery cells are arranged between adjacent limiting beams. The distance between the adjacent two limiting beams in the thickness direction is D1. In the thickness direction, the distance between the adjacent two limiting beams is D1, and the sum of the sizes of all the electrode assemblies stacked between the adjacent two limiting beams in the thickness direction is D2. 85%≤D2 / D1≤92%.

[0048] D2 / D1 is limited to be less than or equal to 92% to reduce the swelling pressure of the battery cell, reduce the deformation of the battery cell in the rapid charging process, reduce the risk of cracking of the box, and improve the reliability of the battery; D2 / D1 is limited to be greater than or equal to 85% to improve the space utilization in the thickness direction and improve the energy density of the battery. D2 / D1 is limited to 85%-92%, which can balance the swelling pressure of the battery cell and the energy density of the battery to a certain extent.

[0049] In some embodiments, the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator film between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged between the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises a lithium-containing phosphate with an olivine structure, 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 carbon-based material.

[0050] The carbon-based material has high cycle stability and can improve the cycle performance of the battery cell. The lithium-containing phosphate has high cycle stability, and using the lithium-containing phosphate as the positive electrode active material can improve the cycle decay of the battery cell caused by excessive temperature rise in the rapid charging process.

[0051] In some embodiments, the single-sided coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , which can be 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2The single-side coating weight of the negative electrode film layer is limited in the above range, which can limit the heat generation of the negative electrode sheet per unit area, reduce the temperature rise of the battery cell, especially the temperature rise during fast charging.

[0052] In some embodiments, the compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 , and can be 1.25 g / cm 3 to 1.36 g / cm 3 The compaction density of the negative electrode film layer is in the above range, which is beneficial to improve the energy density of the battery cell; and because the negative electrode active material in the negative electrode film layer is packed more tightly, the contact resistance between particles is smaller, which can reduce the resistance of the negative electrode sheet, thereby reducing heat generation and improving the fast charging capability of the battery.

[0053] In some embodiments, the porosity of the negative electrode sheet is 27%-40%.

[0054] 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 swelling pressure of the battery cell, reduce the deformation of the battery cell, improve the cycle performance of the battery cell, and improve the reliability of the battery cell during fast charging. The porosity of the negative electrode sheet is less than or equal to 40%, which can balance the energy density of the battery cell.

[0055] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. Artificial graphite and natural graphite have good conductivity, which can reduce heat generation of the negative electrode sheet during charging and improve the fast charging performance of the battery cell.

[0056] In some embodiments, the negative electrode active material further includes a silicon-based material, and the mass content of silicon in the negative electrode active material is 0.3%-10%, and can be 1%-6%.

[0057] The introduction of the silicon-based material in the negative electrode sheet can not only improve the capacity, but also increase the expansion of the negative electrode sheet. Therefore, by limiting the mass content of silicon in the negative electrode active material to 0.3%-10%, the energy density and expansion of the battery cell can be balanced to some extent, the deformation of the battery cell is reduced, and the cycle performance and fast charging capability of the battery cell are improved.

[0058] In some embodiments, the silicon-based material includes at least one of a silicon oxide compound and a silicon-carbon composite.

[0059] 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, 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.

[0060] The first negative electrode film layer and the second negative electrode film layer can be arranged differently, so as to balance the expansion and capacity of the negative electrode film layer to a certain extent; double-layer coating can construct the pore difference of the negative electrode film layer, reduce the ion transmission tortuosity, reduce the side reaction, and improve the rapid charging performance of the battery cell.

[0061] In some embodiments, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer is 3:7 to 7:3, and optionally 4:6 to 6:4. By adjusting the thickness ratio of the first negative electrode film layer to the second negative electrode film layer, the gradient pore difference between the upper and lower layers can be further increased, the lithium ion transmission tortuosity can be reduced, and the rapid charging capability of the battery cell can be improved.

[0062] In some embodiments, the thickness of the first negative electrode film layer is less than or equal to the thickness of the second negative electrode film layer, which can further improve the rapid charging capability of the battery cell.

[0063] 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.

[0064] The particle size of the first negative electrode active material and the second negative electrode active material is different, which can improve the rapid charging performance of the battery cell; in the rapid charging process, the overpotential of the first negative electrode film layer is usually high, and the bottleneck of rapid charging is mainly in the first negative electrode film layer, and the particle size of the first negative electrode active material in the embodiment is relatively small, which can shorten the solid-phase transmission path of ions, improve the rapid charging performance, and improve the ion precipitation problem of the surface layer of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer, and the pores can absorb expansion during charging, reduce the expansion amount of the negative electrode film layer, and improve the reliability of the battery cell in the rapid charging process

[0065] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and optionally 7.8 μm-11.3 μm.

[0066] 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, which can improve the stability of the material; furthermore, the first negative electrode active material within the aforementioned volume average particle size range can cooperate 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.

[0067] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm, and optionally 9.5-14.6 μm.

[0068] Setting the volume average particle size Dv50 of the second negative electrode active material within the above range can enrich the porosity of the second negative electrode film, which is beneficial to improving the fast charging capability of the battery cell and reducing the expansion of the negative electrode film during charging.

[0069] 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.

[0070] In some embodiments, the olivine-structured lithium phosphate has the chemical formula LiFe. 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

[0071] In some embodiments, the single-sided coating weight of the positive electrode film is 200 mg / 1540 mm. 2 -370mg / 1540 / mm 2 ; 240mg / 1540mg is optional 2 Up to 330mg / 1540mm 2 Setting the single-sided coating weight of the positive electrode film within the above range can limit the heat generation per unit area of ​​the positive electrode sheet, while also improving the energy density and charging rate performance of the battery cell.

[0072] In some embodiments, the compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 ; and optionally 2.55 g / cm 3 to 2.70 g / cm 3 . When the compaction density of the positive electrode film layer is within the above range, the energy density of the battery cell can be improved; and since the positive electrode active material in the positive electrode film layer is packed more closely, the contact resistance between particles is smaller, which can further reduce the resistance of the positive electrode sheet, thereby reducing the heat generation under fast charging.

[0073] In some embodiments, the porosity of the positive electrode sheet is 25%-32%. When the porosity of the positive electrode sheet is greater than or equal to 25%, space can be provided for impurities generated by side reactions of the positive electrode sheet, which can reduce the swelling pressure of the battery cell, reduce the deformation of the battery cell, 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 considered to some extent.

[0074] In some embodiments, the thickness of the positive electrode sheet is 0.13 mm-0.2 mm. By using a positive electrode sheet with a smaller thickness, the ion migration path can be shortened, the ion migration rate can be improved, the heat generation of the battery cell can be reduced, and the fast charging performance of the battery cell can be improved.

[0075] In some embodiments, the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer is 0.05-0.3. By limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be greater than or equal to 0.05, the current-carrying capacity of the positive electrode current collector can be improved, the temperature rise of the positive electrode sheet can be reduced, and the fast charging performance of the battery cell can be improved; by limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be less than or equal to 0.3, the loss of the capacity of the positive electrode sheet can be reduced. By limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be 0.05-0.3, the fast charging performance and the energy density of the battery cell can be considered to some extent.

[0076] 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; and 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.

[0077] In some embodiments, the battery cell includes an electrolyte contained in the shell. During the charging and discharging of the battery cell, active ions are embedded and extracted between the positive plate and the negative plate, and the electrolyte plays a role in conducting the active ions between the positive plate and the negative plate.

[0078] In some embodiments, the electrolyte has an electrical conductivity of 15 mS / cm to 20 mS / cm at room temperature. When the electrolyte has an electrical conductivity in the above range, the migration rate of ions 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.

[0079] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of a carbonate solvent and a carboxylate 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.

[0080] In some embodiments, the carbonate solvent includes one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0081] 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 above chain carboxylate solvent has a high electrical conductivity, which is conducive to improving the rapid charging capability of the battery cell.

[0082] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes lithium bisfluorosulfonylimide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bisfluorosulfonylimide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L. 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 cell.

[0083] 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 high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the rapid charging performance of the battery cell.

[0084] In a second aspect, the embodiments of the present application provide a power utilization device, which includes the battery provided by any of the embodiments of the first aspect, and the battery is used to provide electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0085] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on the drawings.

[0086] Fig. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0087] Fig. 2 is a schematic diagram of a battery provided by some embodiments of the present application;

[0088] Fig. 3 is an exploded schematic diagram of a battery cell provided by some embodiments of the present application;

[0089] Fig. 4 is an enlarged schematic diagram of the circle frame in Fig. 2;

[0090] Fig. 5 is a partial cross-sectional schematic diagram of a battery provided by some embodiments of the present application;

[0091] Fig. 6 is a partial cross-sectional schematic diagram of a battery cell provided by some other embodiments of the present application;

[0092] Fig. 7 is a partial cross-sectional schematic diagram of a battery cell provided by some other embodiments of the present application;

[0093] Fig. 8 is a cross-sectional schematic diagram of a battery provided by some embodiments of the present application;

[0094] Fig. 9 is an enlarged schematic diagram of the circle frame in Fig. 8;

[0095] Fig. 10 is a cross-sectional schematic diagram of a battery provided by some other embodiments of the present application;

[0096] Fig. 11 is an enlarged schematic diagram of the square frame in Fig. 10;

[0097] Fig. 12 is a cross-sectional schematic diagram of a support member of a battery provided by some embodiments of the present application;

[0098] Fig. 13 is a schematic diagram of an electrode assembly of a battery cell provided by some embodiments of the present application;

[0099] Fig. 14 is a schematic diagram of a battery cell and a first bus member provided by some embodiments of the present application;

[0100] Fig. 15 is a schematic diagram of the first bus member in Fig. 14;

[0101] Fig. 16 is an exploded schematic diagram of a battery provided by some other embodiments of the present application;

[0102] Fig. 17 is a cross-sectional schematic diagram of a negative electrode sheet of a battery cell provided by some embodiments of the present application;

[0103] FIG. 18 is a cross-sectional view of a negative electrode tab of a battery cell according to some embodiments of the present application;

[0104] FIG. 19 is a cross-sectional view of a positive electrode tab of a battery cell according to some embodiments of the present application.

[0105] Reference signs are explained as follows

[0106] 1, vehicle; 2, battery; 3, controller; 4, motor;

[0107] 10, battery cell; 100, battery cell group;

[0108] 11, electrode assembly; 111, positive electrode tab; 1111, positive current collector; 1112, positive film layer; 112, negative electrode tab; 1121, negative current collector; 1122, negative film layer; 11221, first negative film layer; 11222, second negative film layer; 113, separator; 11a, electrode main body; 11b, first tab; 11c, second tab;

[0109] 12, housing; 121, casing; 122, end cover; 1221, outer surface; 1222, inner surface; 1223, electrode lead-out hole; 12a, first end wall; 12b, second end wall; 12c, side wall; 12d, first side wall; 12e, second side wall;

[0110] 13, first electrode terminal; 131, connecting portion; 1311, through hole; 132, terminal main body; 133, cover plate; 134, recess;

[0111] 14, second electrode terminal; 15, pressure relief mechanism; 151, weak portion; 152, pressure relief portion; 153, fixing portion; 16, sampling member; 17, first fixing member; 18, second fixing member;

[0112] 20, box body; 21, first box wall; 22, second box wall; 23, frame; 24, limiting beam;

[0113] 30, heat exchange member; 31, heat conducting plate; 311, flow channel; 32, insulating layer;

[0114] 40, first adhesive layer; 41, second adhesive layer; 42, third adhesive layer; 43, insulating pad;

[0115] 50, connecting pipe group;

[0116] 60, support member; 61, metal strip; 62, insulating film; 63, cavity;

[0117] 70, first busbar member; 71, first busbar layer; 711, first busbar portion; 712, second busbar portion; 713, first buffer portion; 72, second busbar layer; 721, first laminated portion; 722, second laminated portion; 723, second buffer portion; 73, bent portion;

[0118] 80, mounting beam;

[0119] X, thickness direction; Y, first direction; Z, vertical direction. DETAILED DESCRIPTION

[0120] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be 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 protection scope of the present application.

[0121] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as those 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 the specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, and are not intended to describe a particular order or primary and secondary relationship.

[0122] In the present application, the phrase "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment to other embodiments.

[0123] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "attachment" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0124] The term "and / or", as used in the specification and in claims of the application, indicates that the associated names can exist in three forms, for example, A and / or B can represent: A alone, A and B together, and B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0125] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed description of the same components is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length, width and other dimensions of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0126] The "range" disclosed in the present application is defined in the form of lower limit and upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way can include or not include the end value, and can be arbitrarily combined, i.e. any lower limit can be combined with any upper limit to form a range. For example, if the ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that the ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4 and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise stated, the numerical range "a to b" represents a shorthand representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been listed herein, and "0 to 5" is only a shorthand representation of these numerical combinations. In addition, when a parameter is stated to be ≥2 integers, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0127] "Multiple" appearing in the present application means more than two (including two).

[0128] At present, from the development of market situation, the application of battery is more and more extensive. The battery is not only applied to the energy storage power supply system of hydropower, thermal power, wind power and solar power station, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, and aerospace and other fields. With the continuous expansion of the application field of battery, the market demand is also increasing.

[0129] The battery generally refers to a single physical module including a plurality of battery monomers to provide higher voltage and capacity. The battery monomer can be the smallest unit constituting the battery.

[0130] With the development of batteries, especially the wide use in daily life, users hope that the battery can be charged faster to adapt to the needs of fast-paced modern life. However, in the process of fast charging, the heat generation of the battery cell increases, so that the battery cell maintains in the high temperature interval during the whole charging process, which aggravates the risk of battery thermal runaway and affects the safety of the user.

[0131] In view of this, the embodiments of the present application provide a battery, which sets the pressure relief mechanism of the battery cell downward, so as to spray the high-temperature substances generated downward when the battery appears thermal runaway due to fast charging, reduce the risk of injury to the user, and improve the reliability of the battery.

[0132] The battery described in the embodiments of the present application is suitable for a power consumption device using a battery. The power consumption device can be a device using a battery as a power source or various energy storage systems using a 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 vehicle, a ship, a spacecraft, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0133] The following embodiments take a vehicle as an example for convenience of description.

[0134] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application.

[0135] As shown in FIG. 1, the vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, head or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power source of the vehicle 1.

[0136] 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, for the working power demand of the vehicle 1 during starting, navigation and driving.

[0137] 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, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1.

[0138] FIG. 2 is a schematic diagram of a battery provided by some embodiments of the present application.

[0139] Referring to FIG. 2, in some embodiments, the battery 2 includes a box body 20 and a plurality of battery cells 10 contained in the box body 20.

[0140] The battery cell 10 can be a secondary battery, which refers to a battery cell that can be used continuously by activating active materials through charging after the battery cell is discharged.

[0141] By way of example, the battery cell 10 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium-metal battery cell, a sodium-metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, or the like.

[0142] By way of example, the battery cell 10 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, the prismatic battery cell including a square battery cell, a blade battery cell, a multi-prismatic battery cell, such as a hexagonal battery cell, or the like.

[0143] The plurality of battery cells 10 can be connected in series, in parallel, or in a mixed manner, the mixed manner referring to a manner in which the plurality of battery cells 10 are connected in series and in parallel. The plurality of battery cells 10 can be directly connected in series, in parallel, or in a mixed manner, and the whole of the plurality of battery cells 10 can be accommodated in the case 20. Alternatively, the plurality of battery cells 10 can be connected in series, in parallel, or in a mixed manner to form a battery module, and a plurality of battery modules can be connected in series, in parallel, or in a mixed manner to form a whole, which can be accommodated in the case 20.

[0144] 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.

[0145] FIG. 3 is an exploded schematic view of a battery cell according to some embodiments of the present application.

[0146] Referring to FIG. 3, in some embodiments, the battery cell 10 includes an outer case 12 and an electrode assembly 11 accommodated in the outer case 12.

[0147] The outer case 12 is a hollow structure, and an accommodation space for accommodating the electrode assembly 11 and an electrolyte is formed in the inner portion of the outer case 12. The shape of the outer case 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 outer case can be used.

[0148] By way of example, the outer case 12 includes a case body 121 having an opening and an end cap 122 for closing the opening.

[0149] The case body 121 is a component for fitting the end cap 122 to form an inner cavity of the battery cell 10, and the inner cavity can be used to accommodate the electrode assembly 11, the electrolyte, and other components.

[0150] The shell 121 and the end cover 122 can be separate components. In an example, an opening can be provided on the shell 121, and the end cover 122 can be coupled to the shell 121 by covering the opening.

[0151] The shell 121 can have various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. In particular, the shape of the shell 121 can be determined according to the specific shape and size of the electrode assembly 11. The shell 121 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the present application does not make special limitations on this.

[0152] The end cover 122 can have a shape that is 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 the material 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 easily deformed when subjected to extrusion and collision, and the battery cell 10 can have higher structural strength and improved reliability.

[0153] The end cover 122 can be connected to the shell 121 by welding, bonding, clamping, or other means.

[0154] The shell 121 can be open at one end or both ends. In some examples, the shell 121 can have a structure that is open at one side, and the end cover 122 is provided as one and covers the shell 121. In other examples, the shell 121 can also have a structure that is open at both ends, and the end cover 122 is provided as two, and the two end covers 122 cover the two openings of the shell 121, respectively.

[0155] The electrode assembly 11 is a component in which electrochemical reactions occur in the battery cell 10. The shell 121 can contain one or more electrode assemblies 11.

[0156] In some embodiments, the electrode assembly 11 includes a positive electrode sheet and a negative electrode sheet. During charging and discharging of the battery cell 10, active ions (such as lithium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet.

[0157] In some embodiments, the electrode assembly 11 further includes a separator film, which is disposed between the positive electrode sheet and the negative electrode sheet, and can prevent short circuiting of the positive and negative electrodes while allowing the active ions to pass through.

[0158] In some embodiments, the electrode assembly 11 includes an electrode body 11a, a first tab 11b, and a second tab 11c, the first tab 11b and the second tab 11c being drawn out from the electrode body 11a. The first tab 11b and the second tab 11c are opposite in polarity, in other words, one of the first tab 11b and the second tab 11c is a positive tab, and the other is a negative tab.

[0159] As an example, a portion of the positive electrode sheet having the active material and a portion of the negative electrode sheet having the active material and the separator film constitute the electrode assembly 11. A portion of the positive electrode sheet not having the active material constitutes the positive tab, and a portion of the negative electrode sheet not having the active material constitutes the negative tab. The positive tab and the negative tab can be located together at one end of the electrode body 11a or at two ends of the electrode body 11a, respectively.

[0160] In some embodiments, the electrode assembly 11 is a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound into the jelly-roll structure.

[0161] In some embodiments, the electrode assembly 11 is a stacked structure.

[0162] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be alternately stacked.

[0163] As an example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet is folded to form a plurality of folded segments that are stacked.

[0164] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded segments that are stacked.

[0165] As an example, a plurality of separator films can be provided, and each of the plurality of separator films is provided between any adjacent positive electrode sheet or negative electrode sheet.

[0166] As an example, the separator film can be continuously provided, and is provided between any adjacent positive electrode sheet or negative electrode sheet by a folding or winding manner.

[0167] In some embodiments, the battery cell 10 includes a first electrode terminal 13 and a second electrode terminal 14 that are insulated from each other, the first electrode terminal 13 being electrically connected to the first tab 11b, and the second electrode terminal 14 being electrically connected to the second tab 11c.

[0168] The first electrode terminal 13 and the second electrode terminal 14 are used to be electrically connected to an external circuit to achieve charging or discharging of the battery cell 10.

[0169] As an example, the first electrode terminal 13 can be a separately formed component that is mounted to the housing 12. Alternatively, the first electrode terminal 13 can also be a part of the housing 12.

[0170] As an example, the second electrode terminal 14 can be a separately formed component that is mounted to the housing 12. Alternatively, the second electrode terminal 14 can also be part of the housing 12.

[0171] In some embodiments, both the first electrode terminal 13 and the second electrode terminal 14 are provided on the end cap 122.

[0172] In some embodiments, the battery cell 10 further comprises a pressure relief mechanism 15. The pressure relief mechanism 15 has an important impact on the reliability of the battery cell 10. For example, when a short circuit, overcharge, or the like occurs, thermal runaway can occur inside the battery cell 10, causing a sudden increase in pressure. In this case, the internal pressure can be released outward by actuating the pressure relief mechanism 15, thereby reducing the risk of explosion or fire of the battery cell 10.

[0173] Illustratively, the pressure relief mechanism 15 refers to an element or component that is actuated to release internal gas when the internal pressure or temperature of the battery cell 10 reaches a predetermined threshold. The threshold is designed differently depending on the design requirements. The threshold can depend on the material of one or more of the positive electrode sheet, the negative electrode sheet, the electrolyte, and the separator film in the battery cell 10.

[0174] The pressure relief mechanism 15 can take the form of, for example, a rupture disc, a gas valve, a pressure relief valve, or a safety valve, and can specifically take the form of a pressure-sensitive element or structure, i.e., when the internal pressure of the battery cell 10 reaches a predetermined threshold, the pressure relief mechanism 15 performs an action or a weak zone provided in the pressure relief mechanism 15 breaks, thereby forming an opening or passage for the internal pressure to be released. Alternatively, the pressure relief mechanism 15 can also take the form of a temperature-sensitive element or structure, i.e., when the internal temperature of the battery cell 10 reaches a predetermined threshold, the pressure relief mechanism 15 performs an action, thereby forming an opening or passage for the internal pressure to be released.

[0175] When the battery cell 10 is in thermal runaway, the discharge of the battery cell 10 includes, but is not limited to, electrolyte, dissolved or split positive and negative electrode sheets, fragments of the separator film, high-temperature and high-pressure gas generated by the reaction, flames, and the like.

[0176] In some embodiments, the pressure relief mechanism 15 is provided on the housing 12. Illustratively, the pressure relief mechanism 15 can be provided on the housing 121 or on the end cap 122.

[0177] FIG. 4 is an enlarged view of the circle in FIG. 2; and FIG. 5 is a partial cross-sectional view of a battery according to some embodiments of the present application.

[0178] Referring to FIGS. 2-5, an embodiment of the present application provides a battery 2 including a case 20 and a battery cell 10. The case 20 includes a first case wall 21. The battery cell 10 is housed in the case 20 and is located on a lower side of the first case wall 21. The battery cell 10 includes a housing 12, an electrode assembly 11, and a pressure relief mechanism 15, the housing 12 is fixed to the first case wall 21, the electrode assembly 11 is housed in the housing 12, the housing 12 includes a first end wall 12a, the first end wall 12a is located on a side of the electrode assembly 11 away from the first case wall 21, and the pressure relief mechanism 15 is provided on the first end wall 12a. The battery cell 10 has a charging time of less than or equal to 10.5 minutes to charge from 10% SOC to 80% SOC at room temperature.

[0179] As an example, the room temperature can be an ambient temperature of 30°C.

[0180] The battery cell 10 can include one or more electrode assemblies 11.

[0181] The electrode assembly 11 can be housed entirely in the housing 12 or can be partially housed in the housing 12.

[0182] As an example, the first case wall 21 can be located on an upper side of the battery cell 10 in a vertical direction Z when the battery 2 is installed in an electrical device. The first case wall 21 does not have to be located on the upper side of the battery cell 10 during production, transportation, and the like of the battery 2.

[0183] The first case wall 21 can be a single-layer structure or a multi-layer structure. The first case wall 21 can be a unitarily formed member or can be formed by connecting a plurality of separately formed members.

[0184] The first end wall 12a can be an end cap 122 or can be a wall of a housing 121.

[0185] The pressure relief mechanism 15 and the first end wall 12a can be unitarily formed,

[0186] In some examples, the pressure relief mechanism 15 and the first end wall 12a can be separately formed members that are connected by welding, adhesion, or the like. For example, the first end wall 12a can be provided with a pressure relief hole that penetrates the first end wall 12a, and the pressure relief mechanism 15 can be mounted to the first end wall 12a and cover the pressure relief hole to separate the space on the inside and outside of the first end wall 12a. In alternative embodiments, the pressure relief mechanism 15 and the first end wall 12a can be a unitarily formed structure.

[0187] The SOC refers to the state of charge of the battery cell 10.

[0188] Exemplarily, 100% SOC and 0% SOC are defined as follows: charging the battery cell 10 to a battery charge upper limit voltage at a constant current charging rate of 0.33C, and then charging at a constant voltage to 0.05C, corresponding to the state of 100% SOC of the battery cell; discharging the battery cell 10 to a cut-off voltage at a constant current discharging rate of 0.33C, corresponding to the state of 0% SOC of the battery cell. Exemplarily, the battery charge upper limit voltage can be 3.8V; the battery discharge cut-off voltage can be 2.0V.

[0189] Exemplarily, the charging time of the battery cell 10 from 10% SOC to 80% SOC is 10.5min, 10min, 9.5min, 9min, 8.5min, 8min, 7.5min, 7min, 6.5min, 6min, 5.5min, 5min, or a range composed of any two of the above values.

[0190] In the embodiments of the present application, the battery cell 10 has a fast charging capability, which can save charging time and improve user experience. During the fast charging process of the battery 2, even if the battery cell 10 is accidentally in thermal runaway, the high-temperature substances generated by the battery cell 10 can be ejected downward through the pressure relief mechanism 15, thereby reducing the thermal impact on the upper side of the battery 2, reducing the risk of user injury, and improving the reliability of the battery 2 and the electric device using the battery 2.

[0191] In some embodiments, the charging steps of the battery 2 or any battery cell 10 constituting the battery 2 from 10% SOC to 80% SOC can be performed as follows:

[0192] charging from 10% SOC to 15% SOC at a constant current of 5.0C;

[0193] charging from 15% SOC to 20% SOC at a constant current of 5.0C;

[0194] charging from 20% SOC to 25% SOC at a constant current of 5.0C;

[0195] charging from 25% SOC to 30% SOC at a constant current of 5.0C;

[0196] charging from 30% SOC to 35% SOC at a constant current of 5.0C;

[0197] charging from 35% SOC to 40% SOC at a constant current of 5.0C;

[0198] charging from 40% SOC to 45% SOC at a constant current of 4.6C;

[0199] charging from 45% SOC to 50% SOC at a constant current of 4.3C;

[0200] from 50% SOC to 55% SOC at 4.0 C constant current;

[0201] from 55% SOC to 60% SOC at 3.7 C constant current;

[0202] from 60% SOC to 65% SOC at 3.4 C constant current;

[0203] from 65% SOC to 70% SOC at 3.1 C constant current;

[0204] from 70% SOC to 75% SOC at 2.9 C constant current;

[0205] from 75% SOC to 80% SOC at 2.7 C constant current.

[0206] As an example, the above charging strategy is performed in an ambient temperature of 30 °C.

[0207] In some embodiments, the battery cell 10 charging step from 0% SOC to 10% SOC can be performed as follows: from 0% SOC to 10% SOC at 5.0 C constant current.

[0208] In some embodiments, the battery cell 10 charging step from 80% SOC to 98% SOC can be performed as follows:

[0209] from 80% SOC to 85% SOC at 1.8 C constant current;

[0210] from 85% SOC to 90% SOC at 1.3 C constant current;

[0211] from 90% SOC to 95% SOC at 0.7 C constant current;

[0212] from 95% SOC to 98% SOC at 0.33 C constant current.

[0213] In some embodiments, the battery cell 10 charging step from 98% SOC to 100% SOC can be performed as follows: from 98% SOC to 100% SOC at 0.01 C, 0.05 C, 0.1 C, or 0.3 C constant current. Alternatively, the battery cell 10 charging step from 98% SOC to 100% SOC can be performed as follows: from 98% SOC to 100% SOC at 0.01 C, 0.05 C, or 0.1 C constant current.

[0214] In some embodiments, the battery cell 10 charging step from 10% SOC to 80% SOC at room temperature can be performed at a constant current of 2 C to 6 C, or alternatively 2.7 C to 5 C. The constant current can vary during the charging process of the battery cell 10 depending on the SOC of the battery cell 10.

[0215] 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 charge strategy and the discharge strategy, the negative electrode tab at the battery cell 10 is disassembled and the lithium precipitation area of the negative electrode tab is observed and measured. The ratio of the area of the lithium precipitation area to the total area of the negative electrode tab is less than 2%.

[0216] As an example, the discharge strategy employs constant current discharge at 0.33C to 2.0V.

[0217] As an example, the charge strategy can be:

[0218] charging from 5% SOC to 10% SOC at 5.0C constant current;

[0219] charging from 5% SOC to 10% SOC at 5.0C constant current;

[0220] charging from 10% SOC to 15% SOC at 5.0C constant current;

[0221] charging from 15% SOC to 20% SOC at 5.0C constant current;

[0222] charging from 20% SOC to 25% SOC at 5.0C constant current;

[0223] charging from 25% SOC to 30% SOC at 5.0C constant current;

[0224] charging from 30% SOC to 35% SOC at 5.0C constant current;

[0225] charging from 35% SOC to 40% SOC at 5.0C constant current;

[0226] charging from 40% SOC to 45% SOC at 4.6C constant current;

[0227] charging from 45% SOC to 50% SOC at 4.3C constant current;

[0228] charging from 50% SOC to 55% SOC at 4.0C constant current;

[0229] charging from 55% SOC to 60% SOC at 3.7C constant current;

[0230] charging from 60% SOC to 65% SOC at 3.4C constant current;

[0231] charging from 65% SOC to 70% SOC at 3.1C constant current;

[0232] charging from 70% SOC to 75% SOC at 2.9C constant current;

[0233] Charge from 75% SOC to 80% SOC at 2.7C constant current;

[0234] Charge from 80% SOC to 85% SOC at 1.8C constant current;

[0235] Charge from 85% SOC to 90% SOC at 1.3C constant current;

[0236] Charge from 90% SOC to 95% SOC at 0.7C constant current;

[0237] Charge from 95% SOC to 98% SOC at 0.33C constant current;

[0238] Charge from 98% SOC to 100% SOC at 0.1C constant current.

[0239] 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% and can be considered as 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% and can be considered as slight lithium precipitation.

[0240] In some embodiments, the pressure relief mechanism 15 comprises a weak portion 151. The weak portion 151 is a portion of the pressure relief mechanism 15 that has relatively small strength, and is a portion of the pressure relief mechanism 15 that is easily broken, fractured, torn or opened.

[0241] In some examples, the present application can form a groove, a notch or other structure in a predetermined region of the pressure relief mechanism 15 to reduce the strength of the pressure relief mechanism 15 in the local region, thereby forming the weak portion 151 on the pressure relief mechanism 15. For example, a thinning treatment is performed on a predetermined region of the pressure relief mechanism 15, and the portion of the pressure relief mechanism 15 that is subjected to the thinning treatment forms the weak portion 151. In other examples, a material treatment can be performed on a predetermined region of the pressure relief mechanism 15 so that the strength of the region is weaker than the strength of other regions, in other words, the region is the weak portion 151.

[0242] In some embodiments, the pressure relief mechanism 15 and the first end wall 12a are independently formed, and the pressure relief mechanism 15 is fixed to the first end wall 12a.

[0243] For example, the pressure relief mechanism 15 comprises a pressure relief portion 152, a weak portion 151 and a fixing portion 153, the weak portion 151 is arranged along the outer periphery of the pressure relief portion 152 and connects the pressure relief portion 152 and the fixing portion 153, and the fixing portion 153 can be used to fix the connection to the first end wall 12a.

[0244] Optionally, the weak portion 151 surrounds the pressure relief portion 152.

[0245] Optionally, the fixed portion 153 is welded to the first end wall 12a.

[0246] In some embodiments, the pressure relief mechanism 15 and the first end wall 12a are integrally formed. Integrally forming the pressure relief mechanism 15 and the first end wall 12a can save the space required for connecting the pressure relief mechanism 15 and the first end wall 12a, provide more space for the pressure relief mechanism 15, improve the pressure relief efficiency, and improve the reliability of the battery 2.

[0247] Integrally forming the pressure relief mechanism 15 and the first end wall 12a can also eliminate the conventional welding process, reduce the heat impact on the weak portion 151 of the pressure relief mechanism 15, and improve the stability of the pressure relief mechanism 15.

[0248] For example, the first end wall 12a can be provided with a groove, a notch, or other structures to form the annular weak portion 151. The weak portion 151 and the area surrounded by the weak portion 151 constitute the pressure relief mechanism 15.

[0249] For example, the first end wall 12a can be the bottom wall of the housing 121.

[0250] In some embodiments, the battery 2 further includes a heat exchange member 30 for heat exchange with the housing 12.

[0251] The heat exchange member 30 can be one or more. For example, the battery cell 10 can exchange heat with only one heat exchange member 30, or can exchange heat with multiple heat exchange members 30 at the same time.

[0252] The heat exchange member 30 can directly contact the housing 12 for heat exchange, or can indirectly exchange heat with the housing 12 through other heat-conducting structures.

[0253] The heat exchange member 30 can exchange heat with one or more shell walls of the housing 12.

[0254] For example, the heat exchange member 30 can be a separately formed component arranged in the box 20, or can be integrated with the box 20.

[0255] The heat exchange member 30 can be an integrally formed component, or can be spliced from multiple separately formed sub-components.

[0256] During the charging process of the battery 2, the heat exchange member 30 can exchange heat with the housing 12 of the battery cell 10, thereby controlling the temperature of the battery cell 10 within an appropriate range, improving the cycle performance of the battery cell 10, reducing the risk of thermal runaway, and improving the reliability.

[0257] In some embodiments, the housing 12 further comprises a second end wall 12b opposite to the first end wall 12a, and a side wall 12c connecting the first end wall 12a and the second end wall 12b and surrounding the electrode assembly 11, the second end wall 12b being fixed to the first case wall 21.

[0258] As an example, the side wall 12c can be a cylindrical structure. For example, the battery cell 10 is a prismatic battery cell, the side wall 12c can be a prismatic cylindrical structure; for example, the battery cell 10 is a cylindrical battery cell, the side wall 12c can be a cylindrical structure.

[0259] The heat exchange member 30 can exchange heat with at least one of the first end wall 12a, the second end wall 12b, and the side wall 12c.

[0260] In some examples, the heat exchange member 30 is integrated with the first case wall 21. For example, the first case wall 21 is internally provided with a flow channel for the heat exchange medium to flow. The first case wall 21 can exchange heat with the second end wall 12b.

[0261] In other examples, the heat exchange member 30 is located at the lower side of the battery cell 10 and exchanges heat with the first end wall 12a. Optionally, the heat exchange member 30 is arranged to avoid the pressure relief mechanism 15, so as to reduce the interference of the heat exchange member 30 with the actuation of the pressure relief mechanism 15.

[0262] In some embodiments, the heat exchange member 30 is arranged at the side wall 12c. The heat exchange member 30 is configured to exchange heat with the side wall 12c.

[0263] The pressure relief mechanism 15 is arranged at the first end wall 12a, the second end wall 12b is fixed to the first case wall 21, and the heat exchange member 30 is arranged at the side wall 12c, which can reduce the risk of interference of the heat exchange member 30 with the pressure relief mechanism 15 and save space in the vertical direction Z.

[0264] In some embodiments, the side wall 12c comprises two first side walls 12d arranged opposite to each other along the thickness direction X of the battery cell 10, and two second side walls 12e arranged opposite to each other along a first direction Y perpendicular to the thickness direction X, each second side wall 12e connecting the two first side walls 12d. At least one first side wall 12d of the battery cell 10 is connected to the heat exchange member 30.

[0265] In some examples, one first side wall 12d of the battery cell 10 exchanges heat with the heat exchange member 30. Alternatively, two first side walls 12d of the battery cell 10 exchange heat with two heat exchange members 30, respectively.

[0266] The first side wall 12d is the largest shell wall of the shell 12. Connecting the first side wall 12d with the heat exchange member 30 can increase the heat exchange area, improve the heat exchange efficiency, and thus reduce the temperature rise of the battery monomer 10 during fast charging, reduce the risk of thermal runaway, and improve the reliability.

[0267] In some embodiments, the thickness direction X, the first direction Y, and the vertical direction Z are perpendicular to each other two by two.

[0268] In some embodiments, the electrode assembly 11 includes a positive electrode sheet including a positive electrode current collector and a positive electrode film layer disposed between the positive electrode current collector, the positive electrode film layer including a positive electrode active material, the positive electrode active material including a lithium-containing phosphate with an olivine structure. One first side wall 12d of the battery monomer 10 is connected with the heat exchange member 30.

[0269] The lithium-containing phosphate with an olivine structure has excellent cycle stability. Using the lithium-containing phosphate with an olivine structure can reduce the heat generation of the battery monomer 10 during fast charging and reduce the risk of thermal runaway of the battery monomer 10. Using the lithium-containing phosphate with an olivine structure can reduce the heat exchange demand. In the present embodiment, only one first side wall 12d of the battery monomer 10 is connected with the heat exchange member 30, which can reduce the number of heat exchange members 30, save space, and improve the energy density of the battery 2.

[0270] Of course, in alternative embodiments, if the capacity of the battery 2 meets the requirements, two first side walls 12d of the battery monomer 10 can be connected with two heat exchange members 30, respectively, to improve the temperature control effect.

[0271] In some embodiments, the battery 2 includes a plurality of battery monomer groups 100, and each battery monomer group 100 includes at least two battery monomers 10 arranged along the first direction Y.

[0272] Exemplarily, the plurality of battery monomers 10 of the battery 2 are arrayed in the box body 20.

[0273] The number of battery monomers 10 of adjacent battery monomer groups 100 can be the same or different.

[0274] In some embodiments, one heat exchange member 30 is arranged between every two battery monomer groups 100.

[0275] The number of battery monomer groups 100 can be even or odd.

[0276] In some examples, the number of battery monomer groups 100 is 2n, n is a positive integer. One heat exchange member 30 is arranged between the 2k-1th battery monomer group 100 and the 2kth battery monomer group 100 along the thickness direction X, k is a natural number from 1 to n. The number of heat exchange members 30 can be n.

[0277] In some examples, the number of the battery cell groups 100 is 2n+1, n is a positive integer. One heat exchange member 30 is arranged between the 2k-1th battery cell group 100 and the 2kth battery cell group 100 along the thickness direction X, k is a natural number from 1 to n. The number of the heat exchange members 30 can be n+1, and one heat exchange member 30 can be arranged in the 2n+1th battery cell group 100.

[0278] In the embodiments of the present application, one heat exchange member 30 can exchange heat with the battery cells 10 of two battery cell groups 100 at the same time, which can reduce the number of the heat exchange members 30 and improve the space utilization and energy density of the battery 2.

[0279] In some examples, the heat exchange member 30 is a plurality of heat exchange members 30 arranged along the thickness direction X. Two battery cell groups 100 are arranged between adjacent heat exchange members 30.

[0280] In some examples, the battery cell group 100 includes m battery cells 10, m is a positive integer greater than 1. The m battery cells 10 of the battery cell group 100 are connected to the same heat exchange member 30.

[0281] In some examples, the heat exchange member 30 is bonded to the first side wall 12d by a first adhesive layer 40. The first adhesive layer 40 can stably connect the heat exchange member 30 and the first side wall 12d to improve the stability of heat exchange between the heat exchange member 30 and the battery cell 10.

[0282] In some examples, the first adhesive layer 40 is a thermally conductive adhesive layer.

[0283] In some examples, the heat exchange member 30 includes a thermally conductive plate 31, and the thermally conductive plate 31 has a flow channel 311 for the flow of a heat exchange medium. The heat exchange medium exchanges heat with the battery cell 10 when flowing through the thermally conductive plate 31.

[0284] As an example, the heat exchange medium can be a liquid or a gas, such as water.

[0285] In some examples, the thermally conductive plate 31 is a metal plate or a non-metal plate.

[0286] In some examples, the heat exchange member 30 further includes an insulating layer 32 arranged on the outer surface of the thermally conductive plate 31 and used to separate the thermally conductive plate 31 and the first side wall 12d.

[0287] The insulating layer 32 can insulate the thermally conductive plate 31 and the first side wall 12d, increase the creepage distance between the thermally conductive plate 31 and the first side wall 12d, and reduce the risk of short circuit.

[0288] In some examples, the insulating layer 32 is bonded to the first adhesive layer 40.

[0289] In some embodiments, the heat-conducting plate 31 is made of an insulating non-metallic material, and the insulating layer can be omitted accordingly.

[0290] In some embodiments, the thermal conductivity of the insulating layer 32 is greater than or equal to 0.1 W / (m·K). The insulating layer 32 has good heat conduction capacity, thereby improving the heat exchange efficiency.

[0291] In some embodiments, at least part of the heat exchange member 30 is configured to be deformable in the thickness direction X. The battery cell 10 will swell during the cycle process, and the heat exchange member 30 can be compressed when the battery cell 10 swells, thereby providing space for the swelling of the battery cell 10, reducing the pressure on the electrode assembly 11, and improving the cycle performance of the battery cell 10.

[0292] In some embodiments, the battery 2 further comprises a connecting pipe set 50 for connecting a plurality of heat exchange members 30. The connecting pipe set 50 can be in communication with the flow channels 311 of the plurality of heat exchange members 30, thereby realizing the flow of the heat exchange medium in the flow channels 311.

[0293] Exemplarily, the connecting pipe set 50 comprises an inlet pipe and an outlet pipe, the inlet pipe being in communication with the flow channels 311 of the plurality of heat exchange members 30, and the outlet pipe being in communication with the flow channels 311 of the plurality of heat exchange members 30.

[0294] The inlet pipe and the outlet pipe can be located on the same side of the plurality of battery cells 10, or can be respectively arranged on the two sides of the plurality of battery cells 10. Alternatively, the inlet pipe and the outlet pipe are respectively arranged on the two sides of the plurality of battery cells 10 along the first direction Y.

[0295] In some embodiments, the battery cell 10 further comprises a sampling member 16 arranged in the shell 12, and the sampling member 16 is used for sampling the temperature of the shell 12.

[0296] The sampling member 16 can be arranged in the shell 12 or outside the shell 12.

[0297] The sampling member 16 can sample the temperature of the shell 12 in real time, so as to monitor and adjust the temperature of the battery cell 10, reduce the risk of abnormal temperature rise of the battery cell 10 during rapid charging, and improve the reliability of the battery 2.

[0298] In some embodiments, the sampling member 16 is arranged in the end cover 122.

[0299] In some embodiments, the sampling member 16 is a plurality of sampling members 16, and the plurality of sampling members 16 can be arranged at positions where the temperature of the battery cell 10 is relatively high during the cycle process.

[0300] In some embodiments, the sampling member 16 comprises a negative temperature coefficient thermistor.

[0301] In some embodiments, the shell 12 is bonded to the first case wall 21 by a second adhesive layer 41. The second adhesive layer 41 can fix the battery cell 10 to the first case wall 21, thereby improving the stability of the battery cell 10. The second adhesive layer 41 facilitates molding and is conducive to simplifying the assembly process.

[0302] In some embodiments, the battery cell 10 further comprises a first electrode terminal 13 disposed at the first end wall 12a, and the electrode assembly 11 comprises an electrode body 11a and a first tab 11b extending from the electrode body 11a, the first electrode terminal 13 being electrically connected to the first tab 11b.

[0303] Providing the first electrode terminal 13 at the first end wall 12a can make full use of the space on the lower side of the battery cell 10, reduce the risk of the first electrode terminal 13 interfering with the connection of the shell 12 to the first case wall 21, and improve the space utilization.

[0304] In some embodiments, the second electrode terminal 14 is also disposed at the first end wall 12a.

[0305] In some embodiments, at least part of the first electrode terminal 13 is located outside the first end wall 12a.

[0306] The side of the first end wall 12a away from the electrode assembly 11 has an outer surface 1221, and at least part of the first electrode terminal 13 is located below the plane of the outer surface 1221 of the first end wall 12a.

[0307] In some examples, the first electrode terminal 13 can be located entirely outside the first end wall 12a; alternatively, in other examples, part of the first electrode terminal 13 is located outside the first end wall 12a, and the other part extends into the shell 12 through the first end wall 12a.

[0308] The part of the first electrode terminal 13 located outside the first end wall 12a can be used to connect to the busbar component of the battery 2.

[0309] In some embodiments, the area of the projection of the part of the first electrode terminal 13 located outside the first end wall 12a on the first end wall 12a is 200mm 2 - 600mm 2 , optionally 200mm 2 , 250mm 2 , 300mm 2 , 350mm 2 , 400mm 2 , 450mm 2 , 500mm 2 , 550mm 2 , or 600mm 2 .

[0310] Exemplarily, the projection of the portion of the first electrode terminal 13 outside the first end wall 12a on the first end wall 12a is the projection of the portion of the first electrode terminal 13 outside the first end wall 12a on the vertical direction Z. The vertical direction Z is parallel to the thickness direction of the first end wall 12a.

[0311] The portion of the first electrode terminal 13 outside the first end wall 12a has a larger area, which can increase the overcurrent area, reduce heat generation, reduce the temperature rise of the first electrode terminal 13 during the cycle of the battery 2, and improve the reliability. The first electrode terminal 13 has a larger exposed area, which can increase the heat dissipation efficiency of the first electrode terminal 13.

[0312] In some embodiments, in the width direction of the first end wall 12a, the size of the first end wall 12a is W1 mm, and the size of the portion of the first electrode terminal 13 outside the first end wall 12a is W2 mm. W2 and W1 satisfy: 0.4≤W2 / W1≤1.

[0313] Optionally, the width direction of the first end wall 12a is parallel to the thickness direction X of the battery cell 10.

[0314] As an example, W2 / W1 is 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0315] Setting W2 / W1 to be greater than or equal to 0.4 can make the first electrode terminal 13 have a larger exposed area, increase the connection area of the first electrode terminal 13 and the current collecting component, improve the overcurrent capacity, reduce the temperature rise, improve the cycle performance of the battery 2, and improve the reliability of the battery 2. Limiting W2 / W1 to be less than or equal to 1 can reduce the space occupied by the first electrode terminal 13 in the width direction, and improve the space utilization.

[0316] In some embodiments, W2 / W1 is 0.6-0.9.

[0317] In some embodiments, the first electrode terminal 13 and the second electrode terminal 14 are arranged along the length direction of the first end wall 12a. Optionally, the length direction of the first end wall 12a is parallel to the first direction Y.

[0318] In some embodiments, in the length direction of the first end wall 12a, the pressure relief mechanism 15 is located between the first electrode terminal 13 and the second electrode terminal 14.

[0319] FIG. 6 is a partial cross-sectional schematic view of a battery cell provided by some embodiments of the present application.

[0320] In some embodiments, referring to FIG. 6, the first end wall 12a has an inner surface 1222 facing the electrode assembly 11, and the first electrode terminal 13 does not protrude beyond the inner surface 1222 in a direction close to the electrode assembly 11.

[0321] In the embodiments of the present application, the first electrode terminal 13 does not occupy the internal space of the shell 12, thereby improving the space utilization of the battery monomer 10 and increasing the energy density of the battery monomer 10.

[0322] In some embodiments, the first end wall 12a includes an electrode lead-out hole 1223, the first electrode terminal 13 is located outside the electrode lead-out hole 1223, and the first electrode terminal 13 covers the electrode lead-out hole 1223 in the axial direction of the electrode lead-out hole 1223.

[0323] In some embodiments, the battery monomer 10 further includes a first fixing member 17 and a second fixing member 18, the first fixing member 17 at least partially surrounds the first electrode terminal 13 and is fixed to the first electrode terminal 13, and the second fixing member 18 is connected to the first fixing member 17 and is fixedly connected to the first end wall 12a.

[0324] In some embodiments, a portion of the second fixing member 18 is embedded in the first fixing member 17.

[0325] In some embodiments, the second fixing member 18 is welded to the first end wall 12a.

[0326] In some embodiments, the first fixing member 17 is an insulating member. The first fixing member 17 is formed by an injection molding process.

[0327] FIG. 7 is a partial cross-sectional view of a battery monomer according to some embodiments of the present application.

[0328] Referring to FIG. 7, in some embodiments, the first electrode terminal 13 includes a connecting portion 131, the connecting portion 131 is provided with a through hole 1311, the first tab 11b is inserted into the through hole 1311, and a portion of the first tab 11b is located on a side of the connecting portion 131 away from the electrode body 11a and is connected to the connecting portion 131.

[0329] By providing the through hole 1311, the first tab 11b can be led out to the outside of the connecting portion 131, thereby reducing the distance between the connecting portion 131 and the electrode body 11a, improving the internal space utilization of the battery monomer 10, and increasing the energy density of the battery monomer 10.

[0330] In some embodiments, the first tab 11b is welded to the connecting portion 131. The first tab 11b can be directly connected to the first electrode terminal 13, thereby eliminating the conventional adapter piece and improving the energy density.

[0331] In some embodiments, the first electrode terminal 13 includes a terminal body 132 fixed to the first end wall 12a, and a cover plate 133 disposed on a side of the terminal body 132 away from the electrode body 11a and connected to the terminal body 132. The cover plate 133 separates the through hole 1311 from the external space of the battery cell 10.

[0332] In some embodiments, the terminal body 132 is provided with a recess 134 on a side away from the electrode body 11a, and the bottom wall of the recess 134 is the connecting portion 131. The cover plate 133 is disposed on a side of the connecting portion 131 away from the electrode body 11a and covers the recess 134.

[0333] The recess 134 can accommodate a portion of the first tab 11b, thereby improving the space utilization. The cover plate 133 separates the external space of the shell 12 from the through hole 1311, thereby achieving sealing and reducing the risk of electrolyte leakage.

[0334] In some embodiments, at least a portion of the cover plate 133 is accommodated in the recess 134. By accommodating the cover plate 133 in the recess 134, the space utilization can be improved.

[0335] In some embodiments, the cover plate 133 is welded to the terminal body 132.

[0336] In some embodiments, the cover plate 133 is spaced apart from the first tab 11b to reduce the risk of the cover plate 133 and the first tab 11b being pressed against each other.

[0337] In some embodiments, the through hole 1311 is a strip-shaped hole extending along the length direction of the first end wall 12a.

[0338] FIG. 8 is a cross-sectional view of a battery according to some embodiments of the present application; and FIG. 9 is an enlarged view of the circular frame in FIG. 8.

[0339] Referring to FIGS. 8 and 9, in some embodiments, the box body 20 further includes a second box wall 22 disposed on the lower side of the battery cell 10 and opposite to the first box wall 21.

[0340] The second box wall 22 can be a single-layer structure or a multi-layer structure.

[0341] The second box wall 22 can protect the battery cell 10 from the outside, thereby reducing the risk of the battery cell 10 being impacted by external impurities and improving the reliability of the battery 2.

[0342] The battery cell 10 is fixed to the first box wall 21, and the weight of the battery cell 10 is mainly borne by the first box wall 21. Therefore, the second box wall 22 can have a smaller thickness and weight.

[0343] In some embodiments, the box 20 further comprises a frame 23, and the first box wall 21 and the second box wall 22 are respectively located on the upper side and the lower side of the frame 23. The first box wall 21, the second box wall 22 and the frame 23 define an internal space for accommodating the battery cell 10 and the heat exchange member 30.

[0344] In some embodiments, the second box wall 22 is spaced apart from the battery cell 10.

[0345] When the battery cell 10 is in thermal runaway, the space between the second box wall 22 and the battery cell 10 can serve as a discharge channel, thereby timely discharging the substances released by the battery cell 10 to the outside of the box 20, reducing the risk of explosion of the battery 2. When the second box wall 22 is subjected to external impact, the space between the second box wall 22 and the battery cell 10 can play a blocking role, reducing the impact force transmitted to the battery cell 10, reducing the risk of failure of the battery cell 10, and improving the reliability of the battery 2.

[0346] In some embodiments, the pressure relief mechanism 15, the first electrode terminal 13 and the second electrode terminal 14 are all arranged downward, so that the bottom space of the box 20 can be fully utilized, and the space utilization in the vertical direction Z is improved.

[0347] In some embodiments, the battery 2 further comprises a support 60, which is arranged on the lower side of the first end wall 12a and is used to support the first end wall 12a.

[0348] The support 60 can be one or multiple.

[0349] As an example, the support 60 can be in contact with the second box wall 22, or can be spaced apart from the second box wall 22.

[0350] The support 60 can support the battery cell 10, thereby improving the stability of the battery cell 10 and improving the overall structural strength of the battery 2.

[0351] In some embodiments, the box 20 further comprises a second box wall 22 arranged on the lower side of the battery cell 10, and the second box wall 22 is arranged opposite to the first box wall 21. The support 60 is bonded to the first end wall 12a and the second box wall 22.

[0352] The support 60 connects the battery cell 10 and the second box wall 22, thereby improving the overall structural strength of the battery 2.

[0353] In some embodiments, the support 60 is provided with a third adhesive layer 42 on both sides, and the support 60 is bonded to the second box wall 22 and the first end wall 12a through the two third adhesive layers 42 respectively.

[0354] In some embodiments, the elastic modulus of the support 60 is less than the elastic modulus of the second box wall 22.

[0355] The support 60 has a small elastic modulus, and can deform to reduce the force transmitted to the battery cell 10 and reduce the risk of failure of the battery cell 10 when the second case wall 22 is subjected to external impact.

[0356] In some embodiments, the support 60 has a cavity inside. By providing the cavity, the weight of the support 60 can be reduced, and the compressibility of the support 60 can be provided.

[0357] In some embodiments, the support 60 is multiple. The support 60 extends along the thickness direction X of the battery cell 10, and the multiple supports 60 are arranged at intervals along the first direction Y.

[0358] In some embodiments, the first end wall 12a is supported by two supports 60 at both ends along the first direction Y. Exemplarily, the first electrode terminal 13, the pressure relief mechanism 15, and the second electrode terminal 14 are arranged between the two supports 60 along the first direction Y.

[0359] In some embodiments, one support 60 can simultaneously support two battery cells 10 adjacent along the first direction Y.

[0360] In some embodiments, a gap is provided between the support 60 and the heat exchange member 30 in the vertical direction Z.

[0361] FIG. 10 is a cross-sectional view of a battery according to some embodiments of the present application; FIG. 11 is an enlarged view of the box in FIG. 10; FIG. 12 is a cross-sectional view of a support of a battery according to some embodiments of the present application; and FIG. 13 is a schematic view of an electrode assembly of a battery cell according to some embodiments of the present application.

[0362] Referring to FIGS. 10 to 13, in some embodiments, the case 20 further includes multiple limiting beams 24 connected to the first case wall 21, the multiple limiting beams 24 being arranged at intervals along the thickness direction X of the battery cell 10, and multiple battery cells 10 being arranged between any two adjacent limiting beams 24.

[0363] The limiting beam 24 can be two or more. As an example, the battery cell 10 is arranged between any two adjacent limiting beams 24.

[0364] The limiting beam 24 can be used to limit the swelling deformation of the battery cell 10 in the thickness direction X. The limiting beam 24 can directly abut the battery cell 10 in the thickness direction X; alternatively, other components can be arranged between the limiting beam 24 and the battery cell 10, i.e., the limiting beam 24 limits the swelling of the battery cell 10 through the components.

[0365] The limiting beam 24 has high deformation resistance, which can effectively constrain the battery cell 10 in the thickness direction X, reduce the maximum expansion amount of the battery cell 10 in the thickness direction X, and improve the cycle performance of the battery cell 10.

[0366] In some embodiments, an insulating pad 43 is arranged between the battery cell 10 and the limiting beam 24.

[0367] In some embodiments, the support 60 is connected to adjacent limiting beams 24.

[0368] The support 60 can be one or multiple.

[0369] The support 60 can be connected to the limiting beam 24 by welding, clamping, fastening, or other connection methods.

[0370] The support 60 has a strip structure, a line structure, a beam structure, or other structures. For example, the support 60 extends in the thickness direction X of the battery cell 10.

[0371] During the cycle of the battery cell 10, the battery cell 10 expands and exerts a force on the limiting beam 24. The support 60 can provide a restraining force to the limiting beam 24, thereby reducing the deformation of the limiting beam 24 and limiting the expansion amount of the battery cell 10, improving the cycle performance of the battery cell 10, and reducing the risk of cracking of the box body 20.

[0372] In some embodiments, the support 60 can exert a pre-tightening force on adjacent limiting beams 24.

[0373] In some embodiments, the support 60 has a strip structure. The strip structure has low cost and occupies small space. The use of the strip structure support 60 can improve the space utilization rate inside the battery 2 and improve the energy density of the battery 2.

[0374] In some embodiments, the support 60 includes a metal strip 61 and an insulating film 62 covering the metal strip 61, and the insulating film 62 separates the metal strip 61 from the first end wall 12a.

[0375] For example, the metal strip 61 includes a steel strip.

[0376] The metal strip 61 has high strength, which can not only support the battery cell 10 but also effectively constrain the limiting beam 24. The insulating film 62 can insulate and separate the metal strip 61 from the battery cell 10, reducing the risk of short circuit.

[0377] In some embodiments, the support 60 has a cavity 63 inside. By providing the cavity 63, the weight of the support 60 can be reduced.

[0378] In some embodiments, the metal strip 61 has a cavity 63.

[0379] In some embodiments, the support 60 is bonded to the first end wall 12a. The support 60 is bonded to the battery cell 10, which can increase the connection strength of the battery cell 10 and the box 20, reduce the shaking of the battery cell 10 relative to the box 20 when the battery 2 is impacted, and improve the reliability and stability of the battery 2.

[0380] In some embodiments, the support 60 is spaced apart from the second box wall 22 in the vertical direction Z. Alternatively, the support 60 is bonded to the second box wall 22.

[0381] In some embodiments, the support 60 is detachably connected to the limiting beam 24.

[0382] In some embodiments, the support 60 and the limiting beam 24 can be connected by, but not limited to, a bolt connection, a buckle connection, or other detachable connection modes.

[0383] In some embodiments, the expansion pressure of the battery cell 10 in the thickness direction X thereof is 0.5 MPa-2.4 MPa.

[0384] Alternatively, the expansion pressure of the battery cell 10 in the thickness direction X thereof 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.

[0385] As an example, the expansion pressure of the battery cell 10 can be measured in the following manner:

[0386] Discharge the battery cell at a constant current discharge rate of 1C to 2.0V in an environment temperature of 45°C;

[0387] Clamp the battery cell between two clamping plates, wherein the two clamping plates are respectively located on both sides of the battery cell in the thickness direction X and cover a large surface (the large surface is the outer surface of the first side wall 12d);

[0388] Charge the battery cell to 3.8V at a constant current charge rate of 0.8C in an environment temperature of 45°C, detect and record the pressure applied by the battery cell to the clamping plate;

[0389] 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 applied by the battery cell to the clamping plate is recorded;

[0390] The expansion pressure Q of the battery cell in the thickness direction is: maximum pressure / large surface area.

[0391] The expansion pressure of the battery cell 10 is related to the compactness of the electrode assembly 11. The battery cell 10 has an expansion pressure in the thickness direction X greater than or equal to 0.5 MPa, thereby improving the compactness of the electrode assembly 11 and increasing the energy density of the battery cell 10. The expansion pressure of the battery cell 10 in the thickness direction X is less than or equal to 2.4 MPa, so as to limit the deformation of the electrode assembly 11 during the cycle process, reduce the risk of the separator of the electrode assembly 11 being deformed in a pleated manner and the risk of the positive and negative electrode sheets being locally spaced apart, reduce polarization, and improve the cycle performance of the battery cell 10.

[0392] The embodiments of the present application limit the expansion pressure of the battery cell 10 in the thickness direction X to 0.5-2.4 MPa, so as to reduce the expansion deformation of the battery cell 10 during the rapid charging process, improve the cycle performance of the battery cell 10, reduce the risk of the case 20 being cracked, and improve the reliability of the battery 2.

[0393] Limiting the expansion pressure of the battery cell 10 to 1.5-2.0 MPa can reduce the requirement for the strength of the limiting beam 24 and reduce the cost.

[0394] In some embodiments, the case 20 further comprises a plurality of limiting beams 24 connected to the first case wall 21, the plurality of limiting beams 24 are arranged at intervals along the thickness direction X of the battery cell 10, and a plurality of battery cells 10 are arranged between adjacent limiting beams 24. The distance between two adjacent limiting beams 24 in the thickness direction X is D1. In the thickness direction X, the distance between two adjacent limiting beams 24 is D1, and the sum of the sizes of all electrode assemblies 11 arranged between the two adjacent limiting beams 24 and stacked in the thickness direction X is D2. 85%≤D2 / D1≤92%.

[0395] For example, the number of battery cell groups 100 between adjacent limiting beams 24 is M1. The number of a row of battery cells 10 arranged in the thickness direction X between adjacent limiting beams 24 is M1. Each battery cell 10 comprises M2 electrode assemblies 11.

[0396] When the battery 2 is at 0% SOC, the distance between the two limiting beams 24 in the thickness direction X is measured as D1; the battery cell 10 is disassembled and the electrode assembly 11 is taken out, and the thickness of the M1xM2 electrode assemblies 11 arranged in the thickness direction X is measured and summed up to obtain D2.

[0397] For example, when the battery cell 10 is at % SOC, the size of the electrode assembly 11 in the thickness direction X is T; D2=M1xM2xT.

[0398] D2 / D1 is related to the expansion pressure of the battery cell 10. In the embodiments of the present application, D2 / D1 is limited to be less than or equal to 92% to reduce the expansion pressure of the battery cell 10, reduce the deformation of the battery cell 10 during fast charging, reduce the risk of cracking of the box body 20, and improve the reliability of the battery 2; 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%, which can balance the expansion pressure of the battery cell 10 and the energy density of the battery 2 to a certain extent.

[0399] FIG. 14 is a schematic view of a battery cell and a first busbar component provided in some embodiments of the present application; and FIG. 15 is a schematic view of the first busbar component of FIG. 14.

[0400] Referring to FIGS. 14 and 15, in some embodiments, the battery 2 includes a plurality of battery cells 10 and a plurality of busbar components electrically connecting the plurality of battery cells 10.

[0401] The plurality of busbar components can be connected in series, in parallel, or in a mixed manner.

[0402] The plurality of busbar components can have the same structure or different structures.

[0403] In some embodiments, the plurality of busbar components includes at least one first busbar component 70, and the first busbar component 70 includes a first busbar layer 71 and a second busbar layer 72 stacked and connected, and the first busbar layer 71 is electrically connected to at least two battery cells 10 arranged along the thickness direction X.

[0404] The plurality of busbar components can all be the first busbar component 70, or some of them can be the first busbar component 70.

[0405] The first busbar layer 71 and the second busbar layer 72 can be integrally formed. Alternatively, the first busbar layer 71 and the second busbar layer 72 can be independently formed and connected by welding or other means.

[0406] The first busbar component 70 has at least a double-layer structure, and the first busbar layer 71 and the second busbar layer 72 of the first busbar component 70 can both transmit current, so that the first busbar component 70 has a high current-carrying area, thereby reducing the heat generation of the first busbar component 70, improving the fast charging capability of the battery 2, and reducing the risk of thermal runaway.

[0407] The first current collecting component 70 is provided as a double-layer structure under the premise that the current collecting area meets the requirements, which can reduce the requirement on the thickness of the first current collecting layer 71. The battery monomer 10 will swell during the cycle process, thereby stretching the first current collecting layer 71. The first current collecting layer 71 has a smaller thickness and is easy to deform to adapt to the deformation of the battery monomer 10, which reduces the risk of the connection between the battery monomer 10 and the first current collecting layer 71 being pulled apart and improves the reliability of the battery 2.

[0408] In some embodiments, the thickness of the first current collecting layer 71 is 1 mm-2.5 mm. Alternatively, the thickness of the first current collecting layer 71 is 1.2 mm-1.8 mm. For example, the thickness of the first current collecting layer 71 is 1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm or 2.5 mm. The thickness of the first current collecting layer 71 is selected according to the swelling pressure of the battery monomer 10 in the embodiments of the present application, which can balance the current collecting capacity of the first current collecting layer 71 and the deformability of the first current collecting layer 71 to a certain extent, thereby improving the rapid charging capacity and reliability of the battery 2.

[0409] In some embodiments, the thickness of the second current collecting layer 72 is 1 mm-2.5 mm. Alternatively, the thickness of the second current collecting layer 72 is 1.2 mm-1.8 mm. For example, the thickness of the second current collecting layer 72 is 1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm or 2.5 mm.

[0410] The thickness of the second current collecting layer 72 can be selected according to the thickness of the first current collecting layer 71 and the current collecting capacity of the battery to the first current collecting component. For example, when the thickness of the first current collecting layer 71 is small, the second current collecting layer 72 can have a thickness greater than that of the first current collecting layer 71 to improve the current collecting capacity of the first current collecting component.

[0411] In some embodiments, the first current collecting layer 71 is connected to the first electrode terminal 13 of one battery monomer 10 and the second electrode terminal 14 of another battery monomer 10 to connect the two battery monomers 10 in series. Alternatively, the first current collecting layer 71 is connected to the first electrode terminals 13 of two battery monomers 10 to connect the two battery monomers 10 in parallel.

[0412] In some embodiments, the first current collecting layer 71 is welded to the first electrode terminal 13 and / or the second electrode terminal 14.

[0413] In some embodiments, the first busbar component 70 comprises at least one bending portion 73 connecting the first busbar layer 71 and the second busbar layer 72.

[0414] The bending portion 73 can be one or multiple.

[0415] 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 70.

[0416] In some embodiments, the first busbar layer 71 comprises 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 being arranged along the thickness direction X and connected to different battery monomers 10.

[0417] For example, the first busbar portion 711 can be connected to the electrode terminal (the first electrode terminal 13 or the second electrode terminal 14) of one or more battery monomers 10. The second busbar portion 712 can be connected to the electrode terminal (the first electrode terminal 13 or the second electrode terminal 14) of one or more battery monomers 10.

[0418] During the cycle of the battery monomer 10, the battery monomer 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 monomer 10 and the stress at the connection between the second busbar portion 712 and the battery monomer 10, and reducing the risk of failure of the connection between the first busbar layer 71 and the battery monomer 10.

[0419] In some embodiments, the bending portion 73 is not directly connected to the first buffer portion 713. The bending portion 73 is not directly connected to the first buffer portion 713, thereby reducing the influence of the bending portion 73 on the deformation of the first buffer portion 713 and reducing the difficulty of deformation of the first buffer portion 713.

[0420] In some embodiments, the first buffer portion 713 comprises an arch structure.

[0421] In some embodiments, the first busbar portion 711 is located on the lower side of the first electrode terminal 13 of one battery monomer 10 and is connected to the first electrode terminal 13, and the second busbar portion 712 is located on the lower side of the second electrode terminal 14 of another battery monomer 10 and is connected to the second electrode terminal 14.

[0422] 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 connected by at least one bending portion 73. The second laminated portion 722 is laminated with the second busbar portion 712 and connected by at least one bending portion 73. The second buffer portion 723 connects the first laminated portion 721 and the second laminated portion 722.

[0423] For example, the first laminated portion 721 is attached to the first busbar portion 711, and the second laminated portion 722 is attached to the second busbar portion 712.

[0424] During the circulation of the battery 2, a part of the current can be transmitted between the first busbar portion 711 and the second busbar portion 712 through the first laminated portion 721, the second buffer portion 723, and the second laminated portion 722. A plurality of conductive paths are formed between the first busbar portion 711 and the second busbar portion 712, thereby improving the overcurrent capacity.

[0425] During the circulation of the battery cell 10, the battery cell 10 expands and exerts a pulling force on the first busbar layer 71. Both the first buffer portion 713 and the second buffer portion 723 can release stress by deforming, thereby reducing the risk of failure of the connection between the first busbar layer 71 and the battery cell 10.

[0426] In some embodiments, the second buffer portion 723 at least partially overlaps with the first buffer portion 713. In this way, the deformation regions of the first buffer portion 713 and the second buffer portion 723 are close to each other, thereby reducing the risk of interference between the first buffer portion 713 and the second buffer portion 723 when deforming.

[0427] In some embodiments, the second busbar layer 72 is located on the side of the first busbar layer 71 away from the battery cell 10.

[0428] In some embodiments, the second busbar layer 72 is located on the lower side of the first busbar layer 71.

[0429] In some embodiments, the plurality of busbar components further comprises a second busbar component (not shown) having a single-layer structure. In the battery 2, the expansion amounts of the battery cells 10 at different positions can be different. For the battery cell 10 with a smaller expansion amount, the second busbar component with a single-layer structure can be used. Compared with the first busbar component 70, the second busbar component has a simple structure and is easy to manufacture, thereby saving costs. The thickness of the second busbar component is greater than the thickness of the first busbar layer 71 and the thickness of the second busbar layer 72. The overcurrent capacity of the second busbar component can meet the requirements.

[0430] FIG. 16 is an exploded schematic view of a battery according to some embodiments of the present application.

[0431] Referring to FIG. 16, in some embodiments, the first box wall 21 is used as at least part of the floor of the vehicle. Using the first box wall 21 as the floor can save parts of the vehicle, improve the integration of the vehicle, and simplify the assembly process of the vehicle.

[0432] In some embodiments, the battery 2 further comprises a mounting beam 80, which is arranged on the side of the first box wall 21 away from the battery cell 10.

[0433] The mounting beam 80 is connected to the first box wall 21, which can improve the overall strength of the battery 2. The mounting beam 80 can also provide mounting positions for some components of the electric device, thereby reducing parts, improving integration, and simplifying the assembly process.

[0434] In some embodiments, the mounting beam 80 is used to mount the seat of the vehicle. The embodiments of the present application can improve the space utilization of the whole vehicle. The mounting beam 80 in combination with the first box wall 21 can save more space in the vertical direction Z, so as to further increase the size of the battery cell 10 in the vertical direction Z and improve the energy density of the battery 2.

[0435] FIG. 17 is a cross-sectional view of a negative electrode sheet of a battery cell according to some embodiments of the present application; FIG. 18 is a cross-sectional view of a negative electrode sheet of a battery cell according to some other embodiments of the present application; and FIG. 19 is a cross-sectional view of a positive electrode sheet of a battery cell according to some other embodiments of the present application.

[0436] Referring to FIG. 13 and FIGS. 17-19, in some embodiments, the electrode assembly 11 comprises a positive electrode sheet 111, a negative electrode sheet 112, and a separator 113 between the positive electrode sheet 111 and the negative electrode sheet 112, the positive electrode sheet 111 comprises a positive electrode current collector 1111 and a positive electrode film layer 1112 arranged between the positive electrode current collector 1111, the positive electrode film layer 1112 comprises a positive electrode active material, and the positive electrode active material comprises lithium-containing phosphate with olivine structure; the negative electrode sheet 112 comprises 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 comprises a negative electrode active material, and the negative electrode active material comprises carbon-based material.

[0437] In the embodiments of the present application, the negative electrode film layer 1122 can be arranged on only one side of the negative electrode current collector 1121, or can be arranged on both sides of the negative electrode current collector 1121.

[0438] Optionally, the negative electrode film layer 1122 is arranged on both surfaces of the negative electrode current collector 1121 in the thickness direction of the negative electrode current collector 1121. The negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 can adopt the same negative electrode active material, or can adopt different negative electrode active materials; the thicknesses of the negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 can be the same, or can be different.

[0439] Exemplarily, the negative current collector 1121 can adopt a metal foil or a composite current collector. As an example of the metal foil, at least one foil of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy can be adopted. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer can include at least one of copper, 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).

[0440] The negative active material includes a carbon-based material. The carbon-based material has high cycle stability, which can improve the cycle performance of the battery monomer 10.

[0441] The positive current collector 1111 has two surfaces opposite in the thickness direction of the positive current collector 1111, and the positive film layer 1112 is arranged on any one or both of the two opposite surfaces of the positive current collector 1111.

[0442] Exemplarily, the positive current collector 1111 can adopt a metal foil or a composite current collector. As an example of the metal foil, at least one foil of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy can be adopted. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer can include at least one of aluminum, aluminum 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).

[0443] The lithium-containing phosphate has high cycle stability, and the use of the lithium-containing phosphate as the positive active material can improve the cycle decay of the battery monomer 10 caused by excessive temperature rise during rapid charging.

[0444] In some embodiments, a part of the negative current collector 1121 is not covered by the negative film layer 1122; the part of the negative current collector 1121 not covered by the negative film layer 1122 can be used to form a negative tab.

[0445] In some embodiments, the thickness of the negative current collector 1121 is 4 μm to 6 μm. Exemplarily, the thickness of the negative current collector 1121 is 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm or a range formed by any two of the above values.

[0446] In some embodiments, the compaction density of the negative electrode film layer 1122 of the battery cell 10 at 100% SOC is 1.15 g / cm 3 to 1.36 g / cm 3 .

[0447] For example, the compaction density of the negative electrode film layer 1122 of the battery cell 10 at 100% SOC 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 above values.

[0448] For example, the compaction density of the negative electrode film layer of the battery cell 10 at 100% SOC is the meaning known in the art, that is, the compaction density of the negative electrode film layer is measured by disassembling the battery cell at 100% SOC to obtain the negative electrode sheet, for example, a single-side coated negative electrode sheet (if it is a double-side coated negative electrode sheet, the negative electrode film layer on one side can be wiped off first), punching into a small disc with an area of S1, weighing it, recording it as M1, and measuring its thickness H1. Then, the negative electrode film layer of the above weighed negative electrode sheet is wiped off, the weight of the negative electrode current collector is weighed, recorded as M0, and its thickness H0 is measured. The single-side 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-side coating weight of the negative electrode film layer / the thickness of the negative electrode film layer.

[0449] The compaction density of the negative electrode film layer 1122 is related to the expansion of the battery cell 10 at 100% SOC, and the compaction density of the negative electrode film layer 1122 is limited to 1.15 g / cm 3 to 1.36 g / cm 3 , which can to some extent balance the energy density and expansion pressure of the battery cell 10, reduce the deformation of the battery cell 10, and reduce the risk of connection failure of the battery cell 10 and the busbar component.

[0450] The compaction density of the negative film layer 1122 in the above range is beneficial to improve the energy density of the battery monomer 10; and since the negative active material in the negative film layer 1122 is packed more closely, the contact resistance between particles is smaller, which can reduce the resistance of the negative plate 112, thereby reducing heat generation, and is beneficial to improve the rapid charging capability of the battery 2.

[0451] The compaction density of the negative film layer 1122 in the above range can improve the rapid charging capability of the battery monomer 10. The compaction density of the negative film layer 1122 is smaller, which can increase the porosity of the negative plate 112, slow down the expansion of the negative plate, and reduce the expansion pressure of the battery monomer 10.

[0452] In some embodiments, the compaction density of the negative film layer 1122 at 100% SOC of the battery monomer is 1.25 g / cm 3 to 1.36 g / cm 3 , which can improve the energy density of the battery monomer 10.

[0453] In some embodiments, the single-sided coating weight of the negative film layer 1122 is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 . For example, the single-sided coating weight of the negative film layer 1122 is 90 mg / 1540.25 mm 2 , 92 mg / 1540.25 mm 2 , 95 mg / 1540.25 mm 2 , 96 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 102 mg / 1540.25 mm 2 , 104 mg / 1540.25 mm 2 , 105 mg / 1540.25 mm 2 , 108 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 112 mg / 1540.25 mm 2 , 114 mg / 1540.25 mm 2 , 115 mg / 1540.25 mm 2 , 116 mg / 1540.25 mm 2 , 118 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 122 mg / 1540.25 mm 2 , 125 mg / 1540.25 mm 2, 128 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 132 mg / 1540.25 mm 2 , 135 mg / 1540.25 mm 2 , 137 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 142 mg / 1540.25 mm 2 , 145 mg / 1540.25 mm 2 , 148 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 152 mg / 1540.25 mm 2 , 155 mg / 1540.25 mm 2 , 160 mg / 1540.25 mm 2 , 165 mg / 1540.25 mm 2 , 167 mg / 1540.25 mm 2 , 170 mg / 1540.25 mm 2 or a range between any two of the above values.

[0454] The single-side coating weight of the negative electrode film layer 1122 is related to the expansion of the negative electrode film layer. The single-side coating weight of the negative electrode film layer 1122 is limited to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , which can balance the energy density and the expansion pressure of the battery monomer 10 to a certain extent, reduce the deformation of the battery monomer 10, reduce the risk of connection failure of the battery monomer 10 and the busbar component, and improve the reliability.

[0455] In addition, limiting the single-side coating weight of the negative electrode film layer 1122 to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 can also limit the heat generation of the negative electrode sheet 112 per unit area, reduce the temperature rise of the battery monomer 10, especially the temperature rise during rapid charging.

[0456] In some embodiments, the single-side coating weight of the negative electrode film layer 1122 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 , to further balance the energy density and the expansion pressure of the battery monomer 10.

[0457] In some embodiments, the porosity of the negative electrode sheet 112 is 27% to 40%. For example, the porosity of the negative electrode sheet 112 can be 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%.

[0458] The porosity of the negative electrode sheet can be a percentage of the pore volume in the negative electrode sheet to the total volume of the negative electrode sheet. For example, a double-sided coated negative electrode sheet is taken when the battery cell is at 0% state of charge; 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.

[0459] In the embodiments of the present application, the porosity of the negative electrode sheet 112 is greater than or equal to 27%, which can provide space for impurities generated by side reactions of the negative electrode sheet 112, slow down the expansion of the negative electrode sheet 112, reduce the expansion pressure of the battery cell 10, reduce the deformation of the battery cell 10, improve the cycle performance of the battery cell 10, and improve the reliability of the battery cell 10 in the rapid charging process. The porosity of the negative electrode sheet 112 is less than or equal to 40%, which can balance the energy density of the battery cell 10.

[0460] In some embodiments, the carbon-based material includes graphite particles, and the graphitization degree of the graphite particles is 92.0% to 94.5%. For example, the graphitization degree of the graphite particles is 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5%, or a range composed of any two of the above values.

[0461] When the graphitization degree of the graphite particles is in the above range, the conductivity of the graphite particles is relatively excellent, which can reduce the heat generation of the negative electrode sheet 112 and the battery cell 10, and improve the rapid charging performance of the battery cell 10.

[0462] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. The artificial graphite and the natural graphite have good conductivity, which can reduce the heat generation of the negative electrode sheet 112 during charging and improve the rapid charging performance of the battery cell 10.

[0463] In some embodiments, the negative electrode active material further includes a silicon-based material. The introduction of the silicon-based material can improve the capacity of the negative electrode active material and increase the energy density of the battery cell 10.

[0464] In some embodiments, the mass content of the silicon element in the silicon-based material in the negative electrode active material is 0.3% to 10%, and can be 1% to 6% optionally. Illustratively, the mass content of the silicon element in the negative electrode active material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or a range between any two of the above values.

[0465] The introduction of the silicon-based material in the negative electrode sheet 112 can not only improve the capacity, but also increase the expansion of the negative electrode sheet 112. Therefore, the mass content of the silicon element in the negative electrode active material is limited to 0.3% to 10%, which can balance the energy density and expansion of the battery monomer 10 to a certain extent, reduce the deformation of the battery monomer 10, and improve the cycle performance and rapid charging capability of the battery monomer 10.

[0466] The qualitative and quantitative detection of each substance or element in the present application can be carried out by using suitable equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc., and those skilled in the art can also adaptively change certain detection steps / instrument parameters from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used jointly for qualitative or quantitative determination.

[0467] For example, the silicon-based material can be subjected to X-ray powder diffraction test and qualitative analysis by combining JIS / K0131-1996 X-ray Diffraction Analysis Method General Rules with the negative electrode sheet or the negative electrode active material.

[0468] 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.

[0469] In some embodiments, the silicon-based material includes at least one of silicon oxide and silicon-carbon composite.

[0470] 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.

[0471] In some embodiments, the negative electrode film layer 1122 in the embodiments of the present application includes at least one film layer, in other words, the negative electrode film layer 1122 can adopt a single-layer film layer or at least two film layers. Optionally, the negative electrode film layer 1122 includes at least two film layers.

[0472] In the case where the negative electrode film layer 1122 adopts a single-layer film layer, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally further includes a silicon-based material. In the case where a single-layer film layer is adopted, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm to 13.5 μm. Illustratively, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, or a range formed by any two of the above values.

[0473] In the case where the negative electrode film layer 1122 adopts at least two film layers, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally further includes a silicon-based material, which can be located in one of the at least two film layers or in at least two of the at least two film layers. The negative electrode film layer 1122 can include two film layers, three film layers, four film layers, or even more film layers.

[0474] 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.

[0475] The interface of the first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be regular or irregular; and optionally irregular.

[0476] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be differentially arranged, so as to take into account the expansion and capacity of the negative electrode film layer 1122 to some extent; double-layer coating can construct the pore difference of the negative electrode film layer 1122, reduce the ion transmission tortuosity, reduce the side reaction, and improve the rapid charging performance of the battery monomer 10.

[0477] Artificial graphite can have a small volume average particle size Dv50, which can shorten the solid-phase transport path of lithium ions and improve fast charging performance. On the other hand, the material is less prone to agglomeration during the preparation process, which can improve the stability of the material.

[0478] In some embodiments, the thickness ratio of the first negative electrode film layer 11221 to the thickness ratio of the second negative electrode film layer 11222 is 3:7 to 7:3. As an example, the thickness ratio of the first negative electrode film layer 11221 to the thickness ratio of the second negative electrode film layer 11222 is 3:7, 4:6, 5:5, 6:4 or 7:3.

[0479] Optionally, the thickness ratio of the first negative electrode film layer 11221 to the thickness ratio of the second negative electrode film layer 11222 is 4:6 to 6:4.

[0480] By adjusting the thickness ratio of the first negative electrode film layer 11221 and the second negative electrode film layer 11222, the gradient porosity difference between the upper and lower layers can be further increased, the lithium-ion transport tortuosity can be reduced, and the fast charging capability of the battery cell 10 can be improved.

[0481] In some embodiments, the thickness of the first negative electrode film layer 11221 is less than or equal to the thickness of the second negative electrode film layer 11222, which can further improve the fast charging capability of the battery cell 10.

[0482] In some embodiments, the first negative electrode active material is in particulate form, and the second negative electrode active material is in particulate form.

[0483] 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.

[0484] The difference in particle size between the first and second negative electrode active materials improves the fast-charging performance of the battery cell 10. During fast charging, the overpotential of the first negative electrode film 11221 is typically high, and the bottleneck of fast charging mainly lies in the first negative electrode film 11221. However, in this embodiment, 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 alleviate the problem of ion deposition 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 11222. During charging, the pores can absorb expansion, reducing the expansion of the negative electrode film 1122 and improving the reliability of the battery cell 10 during fast charging.

[0485] In some embodiments, the first negative active material has a volume average particle size Dv50 of 7.8-14.3 μm, which can be 7.8-11.3 μm. Illustratively, the first negative active material has a volume average particle size Dv50 of 7.8 μm, 8.0 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.3 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, 13.8 μm, 14 μm, 14.1 μm, 14.3 μm, or a range defined by any two of the above values.

[0486] The first negative active material has a volume average particle size Dv50 of 7.8-14.3 μm, which can shorten the solid-phase transmission path of lithium ions, improve the rapid charging performance, and also can prevent the material from agglomeration during preparation, improve the stability of the material, and further facilitate the construction of the gradient pore difference between the first negative electrode film layer 11221 and the second negative electrode film layer 11222, reduce the tortuosity of lithium ion transmission, and improve the rapid charging performance of the battery cell 10.

[0487] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% of the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% of the volume distribution. The equipment and method known in the art can be used for detection. For example, the negative 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.

[0488] In some embodiments, the second negative active material has a volume average particle size Dv50 of 9.5-18.5 μm, which can be 9.5-14.6 μm.

[0489] Illustratively, the second negative active material has a volume average particle size Dv50 of 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 14.6 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, or a range defined by any two of the above values.

[0490] The volume average particle size Dv50 of the second negative active material is 9.5 μm-18.5 μm, which can make the pores of the second negative film layer 11222 more abundant, and is beneficial to improve the rapid charging capacity of the battery monomer 10 and reduce the expansion of the negative film layer 1122 during the charging process.

[0491] In some embodiments, the first negative active material includes graphite particles, and the volume average particle size Dv50 of the graphite particles in the first negative film layer 11221 is 7.8 μm-14.3 μm, which can be 7.8 μm-11.3 μm. Optionally, the first negative active material includes artificial graphite.

[0492] The second negative active material includes graphite particles, and the volume average particle size Dv50 of the graphite particles is 9.5 μm-18.5 μm, which can be 9.5 μm-14.6 μm. Optionally, the second negative active material includes natural graphite.

[0493] In some embodiments, the specific surface area of the negative active material is 0.5 m 2 / g-3 m 2 / g, which can be 0.6 m 2 / g-1.2 m 2 / g. Exemplarily, the specific surface area of the negative active material is 0.5 m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1.0 m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g, 2.0 m 2 / g, 2.1 m 2 / g, 2.2 m 2 / g, 2.3 m 2 / g, 2.4 m 2 / g, 2.5 m 2 / g, 2.6 m 2 / g, 2.7 m 2 / g, 2.8 m 2 / g, 2.9 m 2 / g, 3.0 m 2 / g or a range of any two of the above values.

[0494] The specific surface area of the material is in the meaning known in the art and can be detected by using devices and methods known in the art, for example, according to the test standard GB / T 19587-2017, taking the negative active material as a sample, and using a Tri-Star 3020 specific surface area and pore size analyzer of the Micromeritics company of the United States to test the specific surface area.

[0495] 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 0.5 m 2 / g, which can improve the ability of the battery monomer 10 to quickly charge; and the specific surface area of the negative active material is limited to be less than or equal to 3 m 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.

[0496] In some embodiments, the lithium-containing olivine phosphate of the olivine structure has a chemical formula of LiFe 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn, and Pb.

[0497] In some embodiments, the lithium-containing olivine phosphate of the olivine structure or the modified material thereof can be a lithium-containing olivine phosphate of the olivine structure or a material obtained after coating modification. For example, the lithium-containing olivine phosphate of the olivine structure includes phosphate particles and an ion-conducting layer, the ion-conducting layer is coated on the surface of the phosphate particles, and the ion-conducting layer contains one or more elements of C, Fe, Ti, Zr, Hf, Ge, and Sn.

[0498] In some embodiments, the mass percentage of the lithium-containing olivine phosphate of the olivine structure or the modified material thereof in the positive active material can be greater than or equal to 80% and less than or equal to 100%, and the positive active material of the present application can be considered to be a lithium-containing olivine phosphate of the olivine structure or a modified material thereof system. When the mass percentage of the lithium-containing olivine phosphate of the olivine structure or the modified material thereof is less than 100%, the positive active material can further include commonly used positive active materials, for example, can include but is not limited to at least one of lithium-containing transition metal oxides. Examples of lithium-containing transition metal oxides can include 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.

[0499] Optionally, the mass percentage of the lithium-containing phosphate with olivine structure or modified material thereof in the positive active material is 100%.

[0500] In some embodiments, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 ; optionally 2.55 g / cm 3 to 2.70 g / cm 3 . For example, the compaction density of the positive electrode film layer 1112 at 100% state of charge (SOC) of the battery cell 10 is 2.50 g / cm 3 , 2.52 g / cm 3 , 2.55 g / cm 3 , 2.56 g / cm 3 , 2.57 g / cm 3 , 2.58 g / cm 3 , 2.60 g / cm 3 , 2.62 g / cm 3 , 2.65 g / cm 3 , 2.68 g / cm 3 , 2.30 g / cm 3 , 2.32 g / cm 3 , 2.75 g / cm 3 , 2.78 g / cm 3 , 2.80 g / cm 3 , or a range formed by any two of the above values.

[0501] When the compaction density of the positive electrode film layer 1112 is within the above range, the energy density of the battery cell 10 can be improved; and since the positive active material in the positive electrode film layer 1112 is packed more closely, the contact resistance between particles is smaller, which can further reduce the resistance of the positive electrode sheet 111, thereby reducing the heat generation under fast charging.

[0502] In the embodiments of the present application, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is a meaning known in the art, that is, the positive electrode film layer 1112 is measured by disassembling the positive electrode sheet 111 from the battery cell 10 at 100% SOC. For example, the test method of the compaction density of the positive electrode film layer 1112 can be the same as the test method of the compaction density of the negative electrode film layer 1122.

[0503] In some embodiments, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540 mm 2 to 370 mg / 1540 mm 2 ; optionally 240 mg / 1540 mm 2to 330 mg / 1540 mm 2 Exemplarily, the single-side coating weight of the positive electrode film layer 1112 is 200 mg / 1540.25 mm 2 210 mg / 1540.25 mm 2 220 mg / 1540.25 mm 2 230 mg / 1540.25 mm 2 240 mg / 1540.25 mm 2 250 mg / 1540.25 mm 2 260 mg / 1540.25 mm 2 270 mg / 1540.25 mm 2 280 mg / 1540.25 mm 2 290 mg / 1540.25 mm 2 300 mg / 1540.25 mm 2 310 mg / 1540.25 mm 2 320 mg / 1540.25 mm 2 330 mg / 1540.25 mm 2 340 mg / 1540.25 mm 2 350 mg / 1540.25 mm 2 360 mg / 1540.25 mm 2 370 mg / 1540.25 mm 2 or a range defined by any two of the above values.

[0504] 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 as follows:

[0505] 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 , which can limit the heat generation per unit area of the positive electrode sheet 111, and can also improve the energy density and charge rate performance of the battery monomer 10.

[0506] In some embodiments, the porosity of the positive electrode sheet 111 is 25%-32%. As an example, the porosity of the positive electrode sheet 111 can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32% or a range defined by any two of the above values.

[0507] 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, such as the porosity test method of the negative electrode sheet 112.

[0508] The porosity of the positive electrode sheet 111 is greater than or equal to 25%, which can provide space for impurities generated by the side reaction of the positive electrode sheet 111, reduce the swelling pressure of the battery monomer, reduce the deformation of the battery monomer 10, 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 balance the energy density of the battery monomer 10 to a certain extent.

[0509] In some embodiments, the thickness of the positive electrode sheet 111 can be 0.13mm-0.2mm. For example, the thickness of the positive electrode sheet 111 can be 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm or a range consisting of any two of the above values.

[0510] 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.

[0511] 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.

[0512] 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. For example, 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 located on one side of the positive electrode current collector 1111.

[0513] For example, 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 consisting of any two of the above values.

[0514] The ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is greater than or equal to 0.05, which 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. The ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is less than or equal to 0.3, which can reduce the loss of the capacity of the positive electrode sheet 111. The ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is limited to 0.05 to 0.3 in the embodiments of the present application, which can balance the rapid charging performance and the energy density of the battery monomer 10 to a certain extent.

[0515] The thickness of the positive electrode film layer and the thickness of the positive electrode current collector are well-known meanings in the art, which can be detected by using well-known devices and methods in the art. For example, the thickness of the positive electrode sheet is measured by using a micrometer, the thickness of the positive electrode current collector is measured by removing the film layer on the surface of the positive electrode current collector, and the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector when the positive electrode film layer is single-sided coated. When the positive electrode film layer is double-sided coated, the thickness of the positive electrode film layer is (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector) / 2.

[0516] 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 consisting of any two of the above values. When the thickness of the positive electrode current collector 1111 is in the above range, the flow capacity of the positive electrode current collector 1111 is relatively excellent, and the battery monomer 10 has a relatively high energy density.

[0517] In some embodiments, a part of the positive electrode current collector 1111 is not covered by the positive electrode film layer 1112. The part of the positive electrode current collector 1111 not covered by the positive electrode film layer 1112 can be used to form a positive electrode tab.

[0518] 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.

[0519] Illustratively, 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 consisting of any two of the above values.

[0520] 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.

[0521] The particle size of the positive electrode active material is relatively small, the lithium ion has a shorter lithium extraction path in the positive electrode active material, and the heat generation is less. Moreover, the particle size of the positive electrode active material is not too small, and the agglomeration can be reduced during the processing and preparation process, so that the performance of the positive electrode active material is stable.

[0522] 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.

[0523] 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 extracted 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.

[0524] In some embodiments, the electrolyte has an electrical conductivity of 13 mS / cm to 20 mS / cm at room temperature (for example, 25°C), which can be 15 mS / cm to 20 mS / cm. Exemplarily, 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.

[0525] 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 generation, and being able to improve the rapid charging performance of the battery cell 10.

[0526] 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 test is performed according to the industry standard HG-T 4067-2015.

[0527] In some embodiments, the density p of the electrolyte at room temperature (e.g., 25°C) satisfies: 1.05 g / mL < p < 1.35 g / mL.

[0528] For example, 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 defined by any two of the above values.

[0529] 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 cell 10, thereby reducing the heat generation and improving the rapid charging performance of the battery cell 10.

[0530] 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.

[0531] 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.

[0532] In some embodiments, the carboxylate-based solvent includes a chain carboxylate-based solvent, and the mass content of the chain carboxylate-based solvent in the organic solvent is 5% to 75%. For example, 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 defined 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.

[0533] In some embodiments, the mass content of the chain carboxylate-based solvent in the organic solvent is 30% to 70%.

[0534] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 each independently includes an alkyl group with 1-5 carbon atoms or a halogenated alkyl group with 1-5 carbon atoms. The above chain carboxylate-based solvent has a relatively high conductivity, which is beneficial to improving the rapid charging capability of the battery cell 10.

[0535] In some embodiments, the carbonate-based solvent includes one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0536] Further optionally, the carbonate-based solvent includes one or more of vinyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.

[0537] The combination of the carbonate solvent and the chain carboxylic ester solvent can improve the conductivity of the electrolyte, and facilitate the migration of lithium ions.

[0538] Further optionally, the mass content of the carbonate solvent in the organic solvent is 5% to 95%, optionally 25% to 60%, and optionally 30% to 45%. For example, the mass content of the carbonate solvent in the organic solvent is 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60%, or a range defined by any two of the above values. The carbonate solvent with the above mass content can further improve the conductivity of the electrolyte, and facilitate the migration of lithium ions.

[0539] For example, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate, and the mass content of the carbonate solvent is 25% to 60%.

[0540] The combination of the organic solvent can improve the conductivity of the electrolyte, reduce the viscosity, and thus improve the fast charging performance of the battery.

[0541] In some embodiments, the electrolyte includes a lithium salt. The lithium salt includes one or more of a fluorine-containing sulfonimide salt and lithium hexafluorophosphate LiPF6. The lithium salt is easy to dissociate, which facilitates 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 cell.

[0542] Optionally, the fluorine-containing sulfonimide salt includes one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0543] In some embodiments, the lithium salt includes lithium bisfluorosulfonylimide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bisfluorosulfonylimide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L. For example, the molar concentration of lithium bisfluorosulfonylimide LiFSI is 0.4 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.7 mol / L. For example, the molar concentration of lithium bisfluorosulfonylimide LiFSI is 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.5 mol / L. For example, the molar concentration of lithium bisfluorosulfonylimide LiFSI is 0.2 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 is 0.8 mol / L.

[0544] 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 values.

[0545] According to some embodiments of the present application, the present application also provides a power consuming device comprising the battery 2 of any of the above embodiments, the battery 2 being configured to provide power to the power consuming device. The power consuming device can be any of the devices or systems mentioned above.

[0546] Referring to FIGS. 2-5, the present application provides a battery 2 comprising a box 20, a plurality of battery cell groups 100, and a plurality of heat exchange members 30, the plurality of battery cell groups 100 and the plurality of heat exchange members 30 being contained in the box 20.

[0547] The box 20 comprises a first box wall 21, a second box wall 22, and a frame 23, the first box wall 21 and the second box wall 22 being oppositely arranged along a vertical direction Z, the frame 23 connecting the first box wall 21 and the second box wall 22, the first box wall 21 being located above the second box wall 22, and the first box wall 21, the second box wall 22, and the frame 23 enclosing a containing space.

[0548] Each battery cell group 100 comprises at least two battery cells 10 arranged along a first direction Y, and the plurality of battery cell groups 100 are arranged along a thickness direction X of the battery cells 10.

[0549] Each two battery cell groups 100 are provided with one heat exchange member 30.

[0550] The battery cell 10 comprises a housing 12, an electrode assembly 11, and a pressure relief mechanism 15, the housing 12 comprising a first end wall 12a, a second end wall 12b, and a side wall 12c, the first end wall 12a being located on a side of the electrode assembly 11 facing the second box wall 22 and being spaced apart from the second box wall 22, and the second end wall 12b being located on a side of the electrode assembly 11 facing the first box wall 21 and being bonded to the first box wall 21.

[0551] The side wall 12c comprises two first side walls 12d and two second side walls 12e, the two first side walls 12d being oppositely arranged along a thickness direction X of the battery cell 10, the two second side walls 12e being oppositely arranged along a first direction Y perpendicular to the thickness direction X, and each second side wall 12e connecting the two first side walls 12d. One first side wall 12d of the battery cell 10 is connected to and exchanges heat with the heat exchange member 30.

[0552] The pressure relief mechanism 15 is arranged on the first end wall 12a.

[0553] The charging time of the battery cell 10 from 10% SOC to 80% SOC at room temperature can be 5 min to 10.5 min.

[0554] 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.

[0555] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements 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

1. A battery, comprising: The enclosure, including the first enclosure wall; A battery cell is housed within a casing and located on the lower side of the first casing wall. The battery cell includes a housing, an electrode assembly, and a pressure relief mechanism. The housing is fixed to the first casing wall, and the electrode assembly is housed within the housing. The housing includes a first end wall located on the side of the electrode assembly away from the first casing wall. The pressure relief mechanism is disposed on the first end wall. Specifically, under room temperature conditions, the charging time for the battery cell from 10% SOC to 80% SOC is 5 to 10.5 minutes.

2. The battery according to claim 1, wherein, The pressure relief mechanism and the first end wall are integrally formed.

3. The battery according to claim 1 or 2 further includes a heat exchanger for exchanging heat with the outer casing.

4. The battery according to claim 3, wherein, The housing also includes a second end wall and a side wall, the first end wall and the second end wall are disposed opposite to each other, the side wall connects the first end wall and the second end wall and surrounds the electrode assembly, and the second end wall is fixed to the first housing wall; The heat exchanger is disposed on the side wall.

5. The battery according to claim 4, wherein, The sidewall includes two first sidewalls and two second sidewalls. The two first sidewalls are arranged opposite each other along the thickness direction of the battery cell, and the two second sidewalls are arranged opposite each other along a first direction perpendicular to the thickness direction. Each second sidewall is connected to the two first sidewalls. At least one of the first sidewalls of the battery cell is connected to the heat exchanger.

6. The battery according to claim 5, 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 between the positive current collector, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes a lithium phosphate with an olivine structure; One of the first sidewalls of the battery cell is connected to the heat exchanger.

7. The battery according to claim 5, comprising a plurality of battery cell groups and a plurality of heat exchange components, wherein the plurality of battery cell groups are arranged along the thickness direction, and each battery cell group includes at least two battery cells arranged along the first direction; A heat exchanger is provided between every two battery cell groups.

8. The battery according to any one of claims 5-7, wherein, The heat exchanger is bonded to the first sidewall by a first adhesive layer.

9. The battery according to any one of claims 5-8, wherein, The heat exchanger includes a heat-conducting plate, and the heat-conducting plate has a flow channel inside for the flow of the heat exchange medium.

10. The battery according to claim 9, wherein, The heat exchanger also includes an insulating layer disposed on the outer surface of the heat-conducting plate and used to separate the heat-conducting plate from the first sidewall.

11. The battery according to claim 10, wherein, The thermal conductivity of the insulating layer is greater than or equal to 0.1 W / (m·K).

12. The battery according to any one of claims 1-11, wherein, The outer shell is bonded to the first box wall by a second adhesive layer.

13. The battery according to any one of claims 1-12, wherein, The battery cell further includes a first electrode terminal disposed on the first end wall, and the electrode assembly includes an electrode body and a first tab extending from the electrode body, wherein the first electrode terminal is electrically connected to the first tab.

14. The battery according to claim 13, wherein, The area of ​​the portion of the first electrode terminal located on the outer side of the first end wall projected onto the first end wall is 200 mm². 2 -600mm 2 .

15. The battery according to claim 13 or 14, wherein, The first end wall has an inner surface facing the electrode assembly, and the first electrode terminal does not extend beyond the inner surface in a direction close to the electrode assembly.

16. The battery according to any one of claims 13-15, wherein, The first electrode terminal includes a connecting portion, the connecting portion having a through hole, the first electrode tab passing through the through hole, and a portion of the first electrode tab being located on the side of the connecting portion away from the electrode body and connected to the connecting portion.

17. The battery according to claim 16, wherein, The first electrode terminal includes a terminal body and a cover plate. The terminal body is fixed to the first end wall. A recess is provided on the side of the terminal body away from the electrode body. The bottom wall of the recess is the connecting part. The cover plate is disposed on the side of the connection portion away from the electrode body and is used to cover the recess.

18. The battery according to claim 17, wherein, At least a portion of the cover plate is accommodated in the recess.

19. The battery according to any one of claims 13-18, wherein, In the width direction of the first end wall, the dimension of the first end wall is W1 mm, and the dimension of the portion of the first electrode terminal located outside the first end wall is W2 mm. W2 and W1 satisfy: 0.4≤W2 / W1≤1.

20. The battery according to any one of claims 1-19, wherein, The housing also includes a second housing wall, which is disposed on the lower side of the battery cell and is disposed opposite to the first housing wall.

21. The battery according to claim 20, wherein, The second box wall is spaced apart from the battery cell.

22. The battery according to any one of claims 1-21, further comprising a support member disposed on the lower side of the first end wall and used to support the first end wall.

23. The battery according to claim 22, wherein, The housing also includes a second housing wall disposed on the lower side of the battery cell, the second housing wall being disposed opposite to the first housing wall; The support is bonded to the first end wall and the second box wall.

24. The battery according to claim 23, wherein, The elastic modulus of the support member is less than that of the elastic modulus of the second box wall.

25. The battery according to claim 22, wherein, The housing also includes a plurality of limiting beams connected to the first housing wall. The plurality of limiting beams are spaced apart along the thickness direction of the battery cell, and a plurality of battery cells are provided between adjacent limiting beams. The support member is connected to the adjacent limiting beam.

26. The battery according to claim 25, wherein, The support includes a metal strip and an insulating film covering the metal strip, the insulating film separating the metal strip from the first end wall.

27. The battery according to claims 22-26, wherein, The support component has a cavity inside.

28. The battery according to any one of claims 1-27, wherein, The first box wall serves as at least a portion of the vehicle's floor.

29. The battery according to any one of claims 1-28, further comprising a mounting beam disposed on the side of the first casing wall opposite to the battery cell.

30. The battery according to claim 29, wherein, The mounting beam is used to mount the vehicle's seats.

31. The battery according to any one of claims 1-31, wherein, The battery cell also includes a sampling element disposed on the outer casing, the sampling element being used to collect the temperature of the outer casing.

32. The battery according to any one of claims 1-31, wherein, The expansion pressure of the battery cell in its thickness direction is 0.5MPa-2.4MPa.

33. The battery according to any one of claims 1-32, comprising a plurality of said battery cells and a plurality of current-carrying components, wherein the plurality of current-carrying components electrically connect the plurality of battery cells; The plurality of busbar components includes 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 being electrically connected to at least two of the battery cells arranged along the thickness direction.

34. The battery according to claim 33, wherein, The first busbar component includes at least one bend, which connects the first busbar layer and the second busbar layer.

35. The battery according to claim 34, 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 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 by at least one of the bending portions. The second stacked portion is stacked with the second busbar and connected by at least one of the bending portions. The second buffer portion connects the first stacked portion and the second stacked portion.

36. The battery according to any one of claims 1-35, wherein, The housing also includes a plurality of limiting beams connected to the first housing wall. The plurality of limiting beams are spaced apart along the thickness direction of the battery cell, and a plurality of battery cells are provided between adjacent limiting beams. The distance between two adjacent limiting beams in the thickness direction is D1; In the thickness direction, the distance between two adjacent limiting beams is D1, and the sum of the dimensions of all electrode assemblies located between two adjacent limiting beams and stacked along the thickness direction is D2. 85% ≤ D2 / D1 ≤ 92%.

37. The battery according to any one of claims 1-36, wherein, The electrode assembly includes a positive electrode, a negative electrode, and a separator between the positive and negative electrode. The positive electrode includes a positive current collector and a positive electrode film layer disposed between the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes a lithium phosphate with an olivine structure. The negative electrode includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, which includes a carbon-based material.

38. The battery according to claim 37, 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 .

39. The battery according to claim 37 or 38, 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 .

40. The battery according to any one of claims 37-39, wherein, The porosity of the negative electrode is 27%-40%.

41. The battery according to any one of claims 37-40, wherein, The carbon-based material includes at least one of artificial graphite and natural graphite.

42. The battery according to any one of claims 37-41, wherein, The negative electrode active material also includes a silicon-based material, wherein the silicon element in the silicon-based material has a mass content of 0.3% to 10%, optionally 1% to 6%.

43. The battery according to claim 42, wherein, The silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

44. The battery according to any one of claims 37-43, 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.

45. The battery according to claim 44, 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.

46. ​​The battery according to claim 44 or 45, wherein, The thickness of the first negative electrode film is less than or equal to the thickness of the second negative electrode film.

47. The battery according to any one of claims 44-46, 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.

48. The battery according to any one of claims 44-47, 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 9.5-14.6μm.

49. The battery according to any one of claims 37-48, 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.

50. The battery according to any one of claims 37-49, wherein, The olivine-structured lithium phosphate has the chemical formula LiFe. 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

51. The battery according to any one of claims 37-50, wherein, The single-sided coating weight of the positive electrode film is 200 mg / 1540 mm. 2 -370mg / 1540 / mm 2 ; 240mg / 1540mg is optional 2 Up to 330mg / 1540mm 2 .

52. The battery according to any one of claims 37-51, 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 .

53. The battery according to any one of claims 37-52, wherein, The porosity of the positive electrode is 25%-32%.

54. The battery according to any one of claims 37-53, wherein, The thickness of the positive electrode sheet is 0.13mm-0.2mm.

55. The battery according to any one of claims 37-54, wherein, The ratio of the thickness of the positive current collector to the thickness of the positive electrode film is 0.05-0.

3.

56. The battery according to any one of claims 37-55, wherein, The volume average particle size of the positive electrode active material satisfies 1μm≤Dv50≤2μm and 0.4μm≤Dv10≤0.7μm.

57. The battery according to any one of claims 1-56, wherein, The battery cell includes an electrolyte contained within the casing.

58. The battery according to claim 57, wherein, The electrolyte has a conductivity of 15 mS / cm to 20 mS / cm at room temperature.

59. The battery according to claim 57 or 58, wherein, The electrolyte includes an organic solvent, which includes one or more of carbonate solvents and carboxylic acid ester solvents.

60. The battery according to claim 59, wherein, The carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

61. The battery according to claim 59 or 60, 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.

62. The battery according to any one of claims 57-61, wherein, The electrolyte comprises a lithium salt, which includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is from 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) is from 0.5 mol / L to 1.0 mol / L.

63. The battery according to any one of claims 57-62, wherein, The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

64. An electrical device comprising a battery according to any one of claims 1-63, the battery being used to provide electrical energy.

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