Battery and electric device

Abstract

The embodiment of the invention provides a battery and an electric device. The battery comprises a box body and a battery monomer, the box body comprises a first box wall. The single battery is contained in the box body and located on the lower side of the first box wall, the single battery comprises a shell, an electrode assembly and a pressure relief mechanism, the shell is fixed to the first box wall, the electrode assembly is contained in the shell, the shell comprises a first end wall, the first end wall is located on the side, away from the first box wall, of the electrode assembly, and the pressure relief mechanism is arranged on the first end wall. And under the condition of room temperature, the charging time of charging the battery monomer from 10% SOC to 80% SOC is 5-10.5 minutes.

Description

[0001] This application claims the priority of PCT International Application PCT / CN2024 / 102726 entitled "Battery and Electrical Appliance" filed on June 28, 2024, the entire content of which is incorporated herein by reference. Technical Field

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

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

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

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

[0006] In a first aspect, an embodiment of this application provides a battery, which includes a box body and battery cells. The box body includes a first box wall. The battery cells are accommodated in the box body and are located below the first box wall. The battery cells include a housing, an electrode assembly, and a pressure relief mechanism. The housing is fixed to the first box wall. The electrode assembly is accommodated in the housing. The housing includes a first end wall, and the first end wall is located on the side of the electrode assembly away from the first box wall. The pressure relief mechanism is provided on the first end wall. Under room temperature conditions, the charging time of the battery cells from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes.

[0007] The battery cells have fast charging ability, which can save charging time and improve the user experience. During the fast charging process of the battery, even if the battery cells experience thermal runaway due to an accident, the high-temperature substances generated by the battery cells can be ejected downward through the pressure relief mechanism, thereby reducing the thermal impact on the upper side of the battery and reducing the risk of user injury, and improving the reliability of the battery and the electrical appliance 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 exchanger configured to exchange heat with the housing. During the charging process of the battery, the heat exchanger can exchange heat with the housing of the battery cell, thereby controlling the temperature of the battery cell within a suitable range, improving the cycling performance of the battery cell, reducing the risk of thermal runaway, and enhancing reliability.

[0010] In some embodiments, the housing further includes a second end wall and a side wall. The first end wall is disposed opposite to the second end wall. The side wall connects the first end wall and the second end wall and surrounds the electrode assembly. The second end wall is fixed to the first box wall. The heat exchanger is disposed on the side wall. The pressure relief mechanism is disposed on the first end wall. Fixing the second end wall to the first box wall and disposing the heat exchanger on the side wall can reduce the risk of interference between the heat exchanger and the pressure relief mechanism and save space in the vertical direction.

[0011] In some embodiments, the side wall includes two first side walls and two second side walls. The two first side walls are disposed opposite to each other in the thickness direction of the battery cell. The two second side walls are disposed opposite to each other in a first direction perpendicular to the thickness direction. Each second side wall connects the two first side walls. At least one of the first side walls of the battery cell is connected to the heat exchanger. The first side wall is the largest wall of the housing. Connecting the first side wall to the heat exchanger can increase the heat exchange area, improve the heat exchange efficiency, and further reduce the temperature rise of the battery cell and the risk of thermal runaway during fast charging, thereby enhancing reliability.

[0012] In some embodiments, the electrode assembly includes a positive electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed between the positive electrode current collectors. 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 side walls of the battery cell is connected to the heat exchanger.

[0013] The lithium phosphate with an olivine structure has excellent cycling stability. Using the lithium phosphate with an olivine structure can reduce the heat generation of the battery cell during fast charging and the risk of thermal runaway of the battery cell. Using the lithium phosphate with an olivine structure can reduce the heat exchange requirement. In the embodiments of the present application, only one of the first side walls of the battery cell is connected to the heat exchanger, which can reduce the number of heat exchangers, save space, and increase the energy density of the battery.

[0014] In some embodiments, the battery includes a plurality of battery cell groups and a plurality of heat exchangers. The plurality of battery cell groups are arranged in the thickness direction. Each battery cell group includes at least two battery cells arranged in the first direction. One heat exchanger is disposed between every two battery cell groups. One heat exchanger can exchange heat with the battery cells of two battery cell groups simultaneously, which can reduce the number of heat exchangers and improve the space utilization rate and energy density of the battery.

[0015] In some embodiments, the heat exchange member is bonded to the first side wall through the first adhesive layer. The first adhesive layer can stably connect the heat exchange member and 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 includes a heat conducting plate, and a flow channel for the heat exchange medium to flow is provided inside the heat conducting plate. The heat exchange medium exchanges heat with the battery cell when flowing through the heat conducting plate.

[0017] In some embodiments, the heat exchange member further includes an insulating layer, and the insulating layer is disposed on the outer surface of the heat conducting plate and is used to separate the heat conducting plate from the first side wall. The insulating layer can insulate the heat conducting plate from the first side wall, increase the creepage distance between the heat conducting plate and the first side wall, and reduce the short - circuit risk.

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

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

[0020] In some embodiments, the battery cell further includes a first electrode terminal disposed on the first end wall. The electrode assembly includes an electrode main body and a first tab led out from the electrode main 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 cell can be fully utilized, the risk that the first electrode terminal interferes with the connection between the outer shell and the first box wall can be reduced, and the space utilization rate can be 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 200 mm 2 - 600 mm 2 . The part of the first electrode terminal located outside the first end wall has a large area, which can increase the current - carrying area, reduce heat generation, lower the temperature rise of the first electrode terminal during the battery cycle, and improve the reliability. The first electrode terminal has a large 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. Along the direction close to the electrode assembly, the first electrode terminal does not extend beyond the inner surface. The first electrode terminal can not occupy the internal space of the outer shell, thereby improving the space utilization rate of the battery cell and enhancing the energy density of the battery cell.

[0023] In some embodiments, the first electrode terminal includes a connecting portion provided with a through hole. The first tab passes through 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 is 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 utilization rate of the internal space of the battery cell, and increasing the energy density of the battery cell.

[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. A recess is provided on the side of the terminal body away from the electrode body, and the bottom wall of the recess is the connecting portion. The cover plate is disposed on the side of the connecting portion away from the electrode body and is used to cover the recess. The recess can accommodate a part of the first tab, thereby improving the space utilization rate. The cover plate separates the external space of the housing from the through hole to achieve sealing and reduce the risk of electrolyte leakage.

[0025] In some embodiments, at least a part of the cover plate is received in the recess. By using the recess to accommodate the cover plate, the space utilization rate 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 located outside the first end wall is W2 mm. W2 and W1 satisfy: 0.4 ≤ W2 / W1 ≤ 1.

[0027] Setting W2 / W1 to be greater than or equal to 0.4 can make the first electrode terminal have a larger exposed area, increase the connection area between the first electrode terminal and the bus bar component, improve the overcurrent capacity, reduce the temperature rise, improve the cycling performance of the battery, and increase the reliability of the battery. Limiting W2 / W1 to be less than or equal to 1 can reduce the extra space occupied by the first electrode terminal in the width direction and improve the space utilization rate.

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

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

[0030] In some embodiments, the battery further comprises a support member, which is disposed at the lower side of the first end wall and is used to support the first end wall. The support member can support the battery cell, thereby improving the stability of the battery cell and enhancing the overall structural strength of the battery.

[0031] In some embodiments, the box body further includes a second box wall disposed on the lower side of the battery cell, the second box wall being disposed opposite to the first box wall. The support member is bonded to the first end wall and the second box wall. The support member connects the battery cell to the second box wall, thereby improving the structural strength of the battery as a whole.

[0032] In some embodiments, the elastic modulus of the support member is smaller than that of the second box wall. When the second box wall is subjected to external impact, the support member can be deformed to reduce the force transmitted to the battery cell and reduce the risk of battery cell failure.

[0033] In some embodiments, the box body further comprises a plurality of limit beams connected to the first box wall, the plurality of limit beams are arranged at intervals along the thickness direction of the battery cells, and a plurality of battery cells are arranged between adjacent limit beams. The support member connects adjacent limit beams.

[0034] The limit beam has a high deformation resistance and can provide effective constraints on the battery cell in the thickness direction; the support member can provide constraints on the limit beam, thereby reducing the deformation of the limit beam and limiting the expansion of the battery cell, improving the cycle performance of the battery cell and reducing the risk of box cracking.

[0035] In some embodiments, the support member includes 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, which can not only support the battery cell, but also effectively constrain the limit beam. The insulating film can insulate the metal strip from the battery cell to reduce the risk of short circuit.

[0036] In some embodiments, the support member has a cavity inside. By providing the cavity, the weight of the support member 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, which is disposed on a side of the first box wall away from the battery cell. The mounting beam is connected to the first box wall to improve the overall strength of the battery. The mounting beam can also provide mounting positions for some components of the electrical device, thereby reducing parts, improving integration, and simplifying the assembly process.

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

[0040] In some embodiments, the battery cell further includes a sampling member disposed on the outer shell, and the sampling member is used to collect the temperature of the outer shell. The sampling member can collect the temperature of the outer shell in real time, so as to facilitate monitoring and adjusting 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 expansion pressure of the battery cell in its own thickness direction is 0.5 MPa - 2.4 MPa. Limiting the expansion pressure of the battery cell in the thickness direction to 0.5 MPa - 2.4 MPa can reduce the expansion deformation of the battery cell during rapid charging, improve the cycling performance of the battery cell, reduce the risk of box cracking, and enhance the reliability of the battery.

[0042] In some embodiments, the battery includes a plurality of battery cells and a plurality of busbar components, and the plurality of busbar components electrically connect the plurality of battery cells. The plurality of busbar components include at least one first busbar component, and the first busbar component includes a first busbar layer and a second busbar layer that are stacked and connected, and the first busbar layer electrically connects at least two battery cells arranged in the thickness direction.

[0043] The first busbar component has at least a double-layer structure, and both the first busbar layer and the second busbar layer of the first busbar component can conduct current. In this way, the first busbar component can have a relatively large current-carrying area, thereby reducing the heat generation of the first busbar component, enhancing the rapid charging ability of the battery, and reducing the risk of thermal runaway. On the premise that the current-carrying area meets the requirements, setting the first busbar component as a double-layer structure can reduce the requirement for the thickness of the first busbar layer. During the cycling process, the battery cell will expand, thereby stretching the first busbar layer. The first busbar layer has a relatively small thickness and is easy to deform to adapt to the deformation of the battery cell, reducing the risk that the connection between the battery cell and the first busbar layer is torn, and enhancing the reliability of the battery.

[0044] In some embodiments, the first busbar component includes at least one bending portion, and the bending portion connects the first busbar layer and the second busbar layer. The bending portion can connect the first busbar layer and the second busbar layer and conduct current between the first busbar layer and the second busbar layer, thereby enhancing the current-carrying capacity of the first busbar component.

[0045] In some embodiments, the first current collecting layer includes a first current collecting portion, a second current collecting portion, and a first buffer portion connecting the first current collecting portion and the second current collecting portion. The first current collecting portion and the second current collecting portion are arranged along the thickness direction and connected to different battery cells. The second current collecting layer includes a first stacked portion, a second stacked portion, and a second buffer portion. The first stacked portion is stacked with the first current collecting portion and connected through at least one bending portion. The second stacked portion is stacked with the second current collecting portion and connected through at least one bending portion. The second buffer portion connects the first stacked portion and the second stacked portion.

[0046] During the cycling of the battery, a part of the current can be transmitted between the first current collecting portion and the second current collecting portion through the first stacked portion, the second buffer portion, and the second stacked portion. Multiple conductive paths are formed between the first current collecting portion and the second current collecting portion, thereby improving the overcurrent capacity. During the cycling of the battery cell, the battery cell expands and applies a tensile force to the first current collecting layer; both the first buffer portion and the second buffer portion can release stress through deformation, thereby reducing the risk of connection failure between the first current collecting layer and the battery cell.

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

[0048] Limiting D2 / D1 to be less than or equal to 92% can reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell during rapid charging, reduce the risk of box body cracking, and improve the reliability of the battery; limiting D2 / D1 to be greater than or equal to 85% can improve the space utilization rate in the thickness direction and increase the energy density of the battery. Limiting D2 / D1 between 85% - 92% can balance the expansion pressure of the battery cell and the energy density of the battery to a certain extent.

[0049] In some embodiments, the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided between the positive electrode current collectors. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure. The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0050] Carbon-based materials have high cycle stability and can improve the cycle performance of battery cells. Lithium-containing phosphates have high cycle stability. Using lithium-containing phosphates as the cathode active material can improve the cycle attenuation of battery cells caused by excessive temperature rise during rapid charging.

[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 , and may be optionally 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 . Limiting the single-sided coating weight of the negative electrode film layer within the above range 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 rapid 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 may be optionally 1.25 g / cm 3 to 1.36 g / cm 3 . When the compaction density of the negative electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and since the negative electrode active materials in the negative electrode film layer are stacked relatively tightly and the contact resistance between particles is small, the resistance of the negative electrode sheet can be reduced, thereby reducing heat generation, which is beneficial to improving the rapid charging ability of the battery.

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

[0054] When the porosity of the negative electrode sheet is greater than or equal to 27%, it can provide space for impurities generated by side reactions in the negative electrode sheet, slow down the expansion of the negative electrode sheet, reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell, improve the cycle performance of the battery cell, and enhance the reliability of the battery cell during rapid charging. When the porosity of the negative electrode sheet is less than or equal to 40%, the energy density of the battery cell can be taken into account.

[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 electrical conductivity, can reduce the heat generation of the negative electrode sheet during charging, and improve the rapid 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 element in the silicon-based material in the negative electrode active material is 0.3% to 10%, and may be optionally 1% to 6%.

[0057] Introducing a silicon-based material into the negative electrode sheet can not only increase the capacity but also enlarge the expansion of the negative electrode sheet. Therefore, limiting the mass content of silicon element in the negative electrode active material to 0.3% to 10% can, to a certain extent, balance the energy density and expansion of the battery cell, reduce the deformation of the battery cell, and improve the cycle performance and fast charging ability of the battery cell.

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

[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 disposed between the first negative electrode film layer and the negative electrode current collector. The negative electrode active material includes a first negative electrode active material disposed in the first negative electrode film layer and a second negative electrode active material disposed in the second negative electrode film layer. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials.

[0060] The first negative electrode film layer and the second negative electrode film layer can be differentially set to balance the expansion and capacity of the negative electrode film layer to a certain extent; double-layer coating can construct pore differences in the negative electrode film layer, reduce the ion transport tortuosity, reduce side reactions, and improve the fast charging performance of the battery cell.

[0061] In some embodiments, the ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer is 3:7 to 7:3, and can be optionally 4:6 to 6:4. By adjusting the thickness ratio of the first negative electrode film layer and the second negative electrode film layer, the gradient pore difference between the upper and lower layers can be further increased, the lithium ion transport tortuosity can be reduced, and the fast charging ability 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 fast charging ability 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] There are differences in the particle sizes of the first negative electrode active material and the second negative electrode active material, which can improve the fast charging performance of the battery cell; during fast charging, the overpotential of the first negative electrode film layer is usually relatively high, and the bottleneck of fast charging mainly lies in the first negative electrode film layer. In the embodiments of the present application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transmission path of ions, improve the fast charging performance, and can also improve the problem of ion precipitation on the surface layer of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer. During charging, the pores can absorb expansion, reduce the expansion amount of the negative electrode film layer, and improve the reliability of the battery cell during fast charging.

[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 can be optionally 7.8 μm - 11.3 μm.

[0066] By setting the volume average particle size Dv50 of the first negative electrode active material within the above range, on the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material; on the third hand, the first negative electrode active material within the above volume average particle size range can cooperate with the second negative electrode active material, which is beneficial to constructing the gradient pore difference between the first negative electrode film layer and the second negative electrode film layer, reducing the tortuosity of lithium ion transmission, 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 can be optionally 9.5 - 14.6 μm.

[0068] By setting the volume average particle size Dv50 of the second negative electrode active material within the above range, the pores of the second negative electrode film layer can be made more abundant, which is beneficial to improving the fast charging ability of the battery cell and reducing the expansion of the negative electrode film layer during charging.

[0069] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g, and can be optionally 0.6 m 2 / g - 1.2 m 2 / g. By limiting the specific surface area of the negative electrode active material to be greater than or equal to 0.5 m 2 / g, the fast charging ability of the battery cell can be improved; by limiting the specific surface area of the negative electrode active material to be less than or equal to 3 m 2 / g, the side reactions during the storage of the battery cell can be reduced, and the expansion pressure can be reduced.

[0070] In some embodiments, the chemical formula of the lithium-containing phosphate with an olivine structure is LiFe1-x-y Mn x M y PO4, where 0 ≤ x ≤ 1 and 0 ≤ y < 1, and 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 layer is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 ; it can be optionally 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2 By setting the single-sided coating weight of the positive electrode film layer within the above range, the heat generation per unit area of the positive electrode sheet can be restricted, and the energy density and charging rate performance of the battery cell can be improved simultaneously.

[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 ; it can be optionally 2.55 g / cm 3 -2.70 g / cm 3 When the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and since the positive electrode active materials in the positive electrode film layer are stacked 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 during rapid 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%, it can provide space for impurities generated by side reactions in the positive electrode sheet, reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell, and 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 a certain extent.

[0074] In some embodiments, the thickness of the positive electrode sheet is 0.13 mm - 0.2 mm. Using a positive electrode sheet with a smaller thickness can shorten the ion migration path, increase the ion migration rate, reduce the heat generation of the battery cell, and improve the rapid charging performance of the battery cell.

[0075] In some embodiments, the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer is 0.05 - 0.3. Limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be greater than or equal to 0.05 can improve the current-carrying capacity of the positive current collector, reduce the temperature rise of the positive electrode sheet, and improve the fast charging performance of the battery cell; limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be less than or equal to 0.3 can reduce the loss of the capacity of the positive electrode sheet. In the embodiments of the present application, limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be between 0.05 and 0.3 can balance the fast charging ability and energy density of the battery cell to a certain extent.

[0076] In some embodiments, the volume average particle size of the positive active material satisfies 1 µm ≤ Dv50 ≤ 2 µm, and 0.4 µm ≤ Dv10 ≤ 0.7 µm. The particle size of the positive active material is relatively small, the lithium intercalation and deintercalation path of lithium ions in the positive active material is short, and the heat generation is less; moreover, the particle size of the above positive active material is not too small, which can reduce agglomeration during the processing and preparation process, making the performance of the positive active material stable.

[0077] In some embodiments, the battery cell includes an electrolyte accommodated in a housing. During the charge and discharge process of the battery cell, active ions are intercalated and deintercalated back and forth between the positive electrode sheet and the negative electrode sheet, and the electrolyte plays a role in conducting active ions between the positive electrode sheet and the negative electrode sheet.

[0078] In some embodiments, the conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm. When the conductivity of the electrolyte is in the above range, the migration rate of ions in the electrolyte is relatively high, thereby further reducing the internal resistance of the battery cell, reducing heat generation, and improving the fast charging performance of the battery cell.

[0079] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents. The combination of organic solvents can improve the conductivity of the electrolyte and reduce the viscosity, thereby improving the fast charging performance of the battery.

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

[0081] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 each independently include an alkyl group with 1 - 5 carbon atoms or a halogenated alkyl group with 1 - 5 carbon atoms. The above chain-like carboxylate solvents have relatively high conductivity, which is beneficial to improving the fast charging ability of the battery cell.

[0082] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6 , the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is 0.5 mol / L to 1.0 mol / L. The above lithium salts are easy to dissociate, which is beneficial to the rapid migration of lithium ions; and the electrolyte system is relatively stable and not easy to decompose, which can improve the cycle performance of the battery cell.

[0083] In some embodiments, the density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL. When the density ρ of the electrolyte is within the above range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0084] In a second aspect, an electrical device provided by an embodiment of the present application includes the battery provided by any one of the embodiments of the first aspect, and the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE 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 required to be used in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the drawings.

[0086] Figure 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application; Figure 2 is a schematic diagram of a battery provided by some embodiments of the present application; Figure 3 is an exploded schematic diagram of a battery cell provided by some embodiments of the present application; Figure 4 is Figure 2 an enlarged schematic diagram at the round frame; Figure 5 is a partial sectional view schematic diagram of a battery provided by some embodiments of the present application; Figure 6 is a partial sectional view schematic diagram of a battery cell provided by some other embodiments of the present application; Figure 7 is a partial sectional view schematic diagram of a battery cell provided by some other embodiments of the present application; Figure 8 is a sectional view schematic diagram of a battery provided by some embodiments of the present application; Figure 9 is Figure 8 an enlarged schematic diagram at the round frame; Figure 10Schematic cross-sectional view of a battery provided in some other embodiments of the present application; Figure 11 For Figure 10 Enlarged schematic view at the square; Figure 12 Schematic cross-sectional view of a support member of a battery provided in some embodiments of the present application; Figure 13 Schematic diagram of an electrode assembly of a battery cell provided in some embodiments of the present application; Figure 14 Schematic diagram of a battery cell and a first busbar component provided in some embodiments of the present application; Figure 15 For Figure 14 Schematic diagram of the first busbar component of; Figure 16 Explosion schematic view of a battery provided in some other embodiments of the present application; Figure 17 Schematic cross-sectional view of a negative electrode sheet of a battery cell provided in some embodiments of the present application; Figure 18 Schematic cross-sectional view of a negative electrode sheet of a battery cell provided in some other embodiments of the present application; Figure 19 Schematic cross-sectional view of a positive electrode sheet of a battery cell provided in some other embodiments of the present application.

[0087] Explanation of reference numerals is as follows 1. Vehicle; 2. Battery; 3. Controller; 4. Motor; 10. Battery cell; 100. Battery cell group; 11. Electrode assembly; 111. Positive electrode sheet; 1111. Positive current collector; 1112. Positive electrode film layer; 112. Negative electrode sheet; 1121. Negative current collector; 1122. Negative electrode film layer; 11221. First negative electrode film layer; 11222. Second negative electrode film layer; 113. Separator; 11a. Electrode body; 11b. First tab; 11c. Second tab; 12. Outer shell; 121. Housing; 122. End cap; 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; 13. First electrode terminal; 131. Connection part; 1311. Through hole; 132. Terminal body; 133. Cover plate; 134. Concave part; 14. Second electrode terminal; 15. Pressure relief mechanism; 151. Weak part; 152. Pressure relief part; 153. Fixing part; 16. Sampling part; 17. First fixing part; 18. Second fixing part; 20. Housing; 21. First box wall; 22. Second box wall; 23. Frame; 24. Limiting beam; 30. Heat exchanger; 31. Heat conducting plate; 311. Flow channel; 32. Insulating layer; 40. First adhesive layer; 41. Second adhesive layer; 42. Third adhesive layer; 43. Insulating pad; 50. Connection pipe group; 60. Support member; 61. Metal strip; 62. Insulating film; 63. Cavity; 70. First bus bar component; 71. First bus bar layer; 711. First bus bar portion; 712. Second bus bar portion; 713. First buffer portion; 72. Second bus bar layer; 721. First stacked portion; 722. Second stacked portion; 723. Second buffer portion; 73. Bending portion; 80. Installation beam; X. Thickness direction; Y. First direction; Z. Vertical direction. Detailed implementation manners

[0088] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without making creative efforts fall within the scope of protection of the present application.

[0089] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of the present application or the above drawings are used to distinguish different objects and not to describe a specific order or primary-secondary relationship.

[0090] Referring to the embodiments in the present application means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0091] In the description of the present application, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "joined", and "attached" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0092] The term "and / or" in the present application is merely an association relationship describing associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0093] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thicknesses, lengths, widths, etc. of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width, etc. of the integrated device are only illustrative descriptions and should not constitute any limitation to the present application.

[0094] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present application, unless otherwise stated, the numerical range "a to b" represents an abbreviated 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 fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0095] The term "a plurality of" appearing in the present application refers to two or more (including two).

[0096] At present, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric transportation means such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as aerospace. With the continuous expansion of the application fields of batteries, the market demand is also continuously increasing.

[0097] A battery generally refers to a single physical module that includes multiple battery cells to provide higher voltage and capacity. A battery cell can be the smallest unit that makes up a battery.

[0098] With the development of batteries, especially when they are widely used in daily life, users hope that the batteries can be charged faster to meet the needs of the fast-paced modern life. However, during the fast charging process, the heat generation of the battery cells increases, causing the battery cells to maintain in a high-temperature range throughout the charging process, exacerbating the risk of battery thermal runaway and affecting the safety of users.

[0099] In view of this, the embodiments of the present application provide a battery. By setting the pressure relief mechanism of the battery cell downward, when the battery undergoes thermal runaway due to fast charging, the generated high-temperature substances are ejected downward, reducing the risk of user injury and improving the reliability of the battery.

[0100] The battery described in the embodiments of the present application is applicable to electrical devices that use batteries. The electrical device can be a device that uses a battery as a power source or various energy storage systems that use a battery as an energy storage element. The electrical device can be, but is not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, and so on. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0101] For the convenience of description in the following embodiments, the electrical device is taken as a vehicle as an example for illustration.

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

[0103] As Figure 1 shown, a battery 2 is disposed inside the vehicle 1. The battery 2 can be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1. For example, the battery 2 can be used as the operating power source of the vehicle 1.

[0104] The vehicle 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery 2 to supply power to the motor 4. For example, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1.

[0105] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0106] Figure 2 Schematic diagram of the battery provided for some embodiments of the present application.

[0107] Refer to Figure 2 , in some embodiments, the battery 2 includes a box body 20 and a plurality of battery cells 10 accommodated in the box body 20.

[0108] The battery cell 10 can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to be used.

[0109] Exemplarily, the battery cell 10 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium-metal battery cell, a sodium-metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0110] As an example, the battery cell 10 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc.

[0111] The plurality of battery cells 10 can be connected in series, in parallel or in a series-parallel combination. The series-parallel combination means that there are both series and parallel connections among the plurality of battery cells 10. The plurality of battery cells 10 can be directly connected in series, in parallel or in a series-parallel combination together, and then the whole formed by the plurality of battery cells 10 is accommodated in the box body 20; of course, it can also be that the plurality of battery cells 10 are first connected in series, in parallel or in a series-parallel combination to form a battery module, and then the plurality of battery modules are connected in series, in parallel or in a series-parallel combination to form a whole and are accommodated in the box body 20.

[0112] In some embodiments, the box body 20 can be a part of the chassis structure of the vehicle. For example, a part of the box body 20 can become at least a part of the floor of the vehicle, or a part of the box body 20 can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0113] Figure 3 Explosion schematic diagram of the battery cell provided for some embodiments of the present application.

[0114] Refer to Figure 3 , in some embodiments, the battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12.

[0115] The outer shell 12 has a hollow structure, and an accommodation space for accommodating the electrode assembly 11 and the electrolyte is formed inside it. The shape of the outer shell 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 shell can be selected.

[0116] As an example, the outer shell 12 includes a housing 121 and an end cap 122. The housing 121 has an opening, and the end cap 122 is used to cover the opening.

[0117] The housing 121 is a component for cooperating with the end cap 122 to form the internal cavity of the battery cell 10. The formed internal cavity can be used to accommodate the electrode assembly 11, the electrolyte, and other components.

[0118] The housing 121 and the end cap 122 can be independent components. Exemplarily, an opening can be provided on the housing 121, and the end cap 122 is covered at the opening to form the internal cavity of the battery cell 10.

[0119] The housing 121 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 121 can be determined according to the specific shape and size of the electrode assembly 11. The material of the housing 121 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc. The embodiments of the present application do not make special restrictions on this.

[0120] The shape of the end cap 122 can be adapted to the shape of the housing 121 to cooperate with the housing 121. The material of the end cap 122 can be the same as or different from the material of the housing 121. Optionally, the end cap 122 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, the end cap 122 is not easily deformed when being squeezed and collided, so that the battery cell 10 can have higher structural strength and the reliability performance can also be improved.

[0121] The end cap 122 is connected to the housing 121 by welding, bonding, clamping or other means.

[0122] The housing 121 can be open at one end or both ends. In some examples, the housing 121 can be a structure with one side open, and the end cap 122 is provided as one and covers the housing 121. In other examples, the housing 121 can also be a structure with both sides open, and the end cap 122 is provided as two, and the two end caps 122 respectively cover the two openings of the housing 121.

[0123] The electrode assembly 11 is a component in the battery cell 10 where an electrochemical reaction occurs. The housing 121 can contain one or more electrode assemblies 11.

[0124] In some embodiments, the electrode assembly 11 includes a positive electrode sheet and a negative electrode sheet. During the charging and discharging process of the battery cell 10, active ions (such as lithium ions) are intercalated and deintercalated back and forth between the positive electrode sheet and the negative electrode sheet.

[0125] In some embodiments, the electrode assembly 11 further includes a separator membrane. The separator membrane is disposed between the positive electrode sheet and the negative electrode sheet, which can prevent short circuit between the positive and negative electrodes and at the same time allow active ions to pass through.

[0126] 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 are led out from the electrode body 11a. The first tab 11b and the second tab 11c have opposite polarities. 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.

[0127] As an example, the portion of the positive electrode sheet with active material, the portion of the negative electrode sheet with active material, and the separator membrane constitute the electrode assembly 11. The portion of the positive electrode sheet without active material constitutes the positive tab, and the portion of the negative electrode sheet without active material constitutes the negative tab. The positive tab and the negative tab can be located at one end of the electrode body 11a together or at both ends of the electrode body 11a respectively.

[0128] In some embodiments, the electrode assembly 11 is a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0129] In some embodiments, the electrode assembly 11 is a stacked structure.

[0130] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively. The multiple positive electrode sheets and the multiple negative electrode sheets are alternately stacked.

[0131] As an example, multiple positive electrode sheets can be provided. The negative electrode sheet is folded to form multiple stacked folding segments, and a positive electrode sheet is clamped between adjacent folding segments.

[0132] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form multiple stacked folding segments.

[0133] As an example, multiple separator membranes can be provided and are respectively disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0134] As an example, the separator membrane can be continuously provided and is disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0135] 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 is electrically connected to the first tab 11b, and the second electrode terminal 14 is electrically connected to the second tab 11c.

[0136] The first electrode terminal 13 and the second electrode terminal 14 are used for electrically connecting to an external circuit to achieve charging or discharging of the battery cell 10.

[0137] As an example, the first electrode terminal 13 can be an independently formed component, which is installed on the housing 12. Alternatively, the first electrode terminal 13 can also be a part of the housing 12.

[0138] As an example, the second electrode terminal 14 can be an independently formed component, which is installed on the housing 12. Alternatively, the second electrode terminal 14 can also be a part of the housing 12.

[0139] In some embodiments, both the first electrode terminal 13 and the second electrode terminal 14 are provided on the end cap 122.

[0140] In some embodiments, the battery cell 10 further includes 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 short circuit, overcharging and other phenomena occur, it may cause thermal runaway inside the battery cell 10, resulting in a sudden increase in pressure. In this case, the internal pressure can be released outward through the actuation of the pressure relief mechanism 15 to reduce the risk of explosion and fire of the battery cell 10.

[0141] Exemplarily, the pressure relief mechanism 15 refers to an element or component that actuates to release internal gas when the internal pressure or temperature of the battery cell 10 reaches a predetermined threshold. This threshold design varies according to different design requirements. This threshold may depend on one or several materials among the positive electrode plate, negative electrode plate, electrolyte and separator in the battery cell 10.

[0142] The pressure relief mechanism 15 can adopt forms such as an explosion-proof valve, a gas valve, a pressure relief valve or a safety valve, and can specifically adopt a pressure-sensitive element or structure, that is, when the internal pressure of the battery cell 10 reaches a predetermined threshold, the pressure relief mechanism 15 performs an action or a weak area provided in the pressure relief mechanism 15 ruptures, thereby forming an opening or channel for the internal pressure to be released. Alternatively, the pressure relief mechanism 15 can also adopt a temperature-sensitive element or structure, that is, 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 channel for the internal pressure to be released.

[0143] When the battery cell 10 is in thermal runaway, the emissions of the battery cell 10 include but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of the separator, high-temperature and high-pressure gas generated by the reaction, flame, and so on.

[0144] In some embodiments, the pressure relief mechanism 15 is provided on the housing 12. Exemplarily, the pressure relief mechanism 15 can be provided on the housing body 121 or on the end cap 122.

[0145] Figure 4 For Figure 2 An enlarged schematic view at the round frame; Figure 5 A partial cross-sectional schematic view of the battery provided in some embodiments of the present application.

[0146] Referring to Figures 2 to 5 , embodiments of the present application provide a battery 2, which includes a box body 20 and battery cells 10. The box body 20 includes a first box wall 21. The battery cells 10 are accommodated in the box body 20 and are located below the first box wall 21. The battery cells 10 include a housing 12, an electrode assembly 11, and a pressure relief mechanism 15. The housing 12 is fixed to the first box wall 21. The electrode assembly 11 is accommodated in the housing 12. The housing 12 includes a first end wall 12a. The first end wall 12a is located on the side of the electrode assembly 11 away from the first box wall 21. The pressure relief mechanism 15 is provided on the first end wall 12a. At room temperature, the charging time of the battery cell 10 from 10% SOC to 80% SOC is less than or equal to 10.5 minutes.

[0147] As an example, the room temperature can be an ambient temperature of 30°C.

[0148] The battery cell 10 may include one or more electrode assemblies 11.

[0149] The electrode assembly 11 may be entirely accommodated in the housing 12 or partially accommodated in the housing 12.

[0150] As an example, when the battery 2 is installed in an electrical device, the first box wall 21 may be located above the battery cell 10 along the vertical direction Z. During the production, transportation, etc. of the battery 2, the first box wall 21 is not required to be located above the battery cell 10.

[0151] The first box wall 21 may be a single-layer structure or a multi-layer structure. The first box wall 21 may be an integrally formed component or a component formed by connecting multiple independently formed components.

[0152] The first end wall 12a may be an end cap 122 or a wall of the housing 121.

[0153] The pressure relief mechanism 15 and the first end wall 12a may be integrally formed, In some examples, the pressure relief mechanism 15 and the first end wall 12a may be independently formed components, and the two may be connected by welding, bonding or other means. For example, the first end wall 12a is provided with a pressure relief hole that penetrates the first end wall 12a. The pressure relief mechanism 15 is installed on the first end wall 12a and covers the pressure relief hole to separate the spaces on both sides of the first end wall 12a. In an alternative embodiment, the pressure relief mechanism 15 and the first end wall 12a may also be an integrally formed structure.

[0154] The SOC refers to the state of charge of the battery cell 10.

[0155] Exemplarily, 100% SOC and 0% SOC are defined as follows: The battery cell 10 is charged at a constant current rate of 0.33C to the upper limit voltage of battery charging, and then charged at a constant voltage to 0.05C, corresponding to the state of 100% SOC of the battery cell; The battery cell 10 is discharged at a constant current rate of 0.33C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell. Demonstratively, the upper limit voltage of battery charging can be 3.8V; The cut-off voltage of battery discharge can be 2.0V.

[0156] 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.

[0157] In the embodiments of the present application, the battery cell 10 has the ability of fast charging, which can save the charging time and improve the user experience. During the fast charging process of the battery 2, even if the battery cell 10 experiences thermal runaway due to an accident, 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 electrical device using the battery 2.

[0158] 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 carried out as follows: Charge at a constant current of 5.0C from 10% SOC to 15% SOC; Charge at a constant current of 5.0C from 15% SOC to 20% SOC; Charge at a constant current of 5.0C from 20% SOC to 25% SOC; Charge at a constant current of 5.0C from 25% SOC to 30% SOC; Charge at a constant current of 5.0C from 30% SOC to 35% SOC; Charge at a constant current of 5.0C from 35% SOC to 40% SOC; Charge at a constant current of 4.6C from 40% SOC to 45% SOC; Charge at a constant current of 4.3C from 45% SOC to 50% SOC; Charge at a constant current of 4.0C from 50% SOC to 55% SOC; Charge from 55% SOC to 60% SOC at a constant current of 3.7C; Charge from 60% SOC to 65% SOC at a constant current of 3.4C; Charge from 65% SOC to 70% SOC at a constant current of 3.1C; Charge from 70% SOC to 75% SOC at a constant current of 2.9C; Charge from 75% SOC to 80% SOC at a constant current of 2.7C.

[0159] As an example, the above charging strategy is carried out in an environment of 30°C.

[0160] In some embodiments, the charging step of the battery cell 10 from 0% SOC to 10% SOC can be carried out as follows: Charge from 0% SOC to 10% SOC at a constant current of 5.0C.

[0161] In some embodiments, the charging step of the battery cell 10 from 80% SOC to 98% SOC can be carried out as follows: Charge from 80% SOC to 85% SOC at a constant current of 1.8C; Charge from 85% SOC to 90% SOC at a constant current of 1.3C; Charge from 90% SOC to 95% SOC at a constant current of 0.7C; Charge from 95% SOC to 98% SOC at a constant current of 0.33C.

[0162] In some embodiments, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be carried out as follows: Charge from 98% SOC to 100% SOC at a constant current of 0.01C, 0.05C, 0.1C or 0.3C. Optionally, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be carried out as follows: Charge from 98% SOC to 100% SOC at a constant current of 0.01C, 0.05C or 0.1C.

[0163] In some embodiments, at room temperature, during the process of charging the battery cell 10 from 10% SOC to 80% SOC, the charging current can be 2C - 6C, and can be optionally 2.7C - 5C. During the charging process of the battery cell 10, the charging current can vary according to the SOC of the battery cell 10.

[0164] In some embodiments, the battery cell 10 is a lithium - ion battery cell. After cycling the battery cell 10 20 times according to the charging strategy and the discharging strategy, disassemble the negative electrode sheet of the battery cell 10, and observe and measure the lithium - plating area of the negative electrode sheet. The ratio of the area of the lithium - plating region to the total area of the negative electrode sheet is less than 2%.

[0165] As an example, the discharging strategy is to discharge at a constant current of 0.33C until 2.0V.

[0166] As an example, the charging strategy can be: Charge at a constant current of 5.0C from 0% SOC to 5% SOC; Charge at a constant current of 5.0C from 5% SOC to 10% SOC; Charge at a constant current of 5.0C from 10% SOC to 15% SOC; Charge at a constant current of 5.0C from 15% SOC to 20% SOC; Charge at a constant current of 5.0C from 20% SOC to 25% SOC; Charge at a constant current of 5.0C from 25% SOC to 30% SOC; Charge at a constant current of 5.0C from 30% SOC to 35% SOC; Charge at a constant current of 5.0C from 35% SOC to 40% SOC; Charge at a constant current of 4.6C from 40% SOC to 45% SOC; Charge at a constant current of 4.3C from 45% SOC to 50% SOC; Charge at a constant current of 4.0C from 50% SOC to 55% SOC; Charge at a constant current of 3.7C from 55% SOC to 60% SOC; Charge at a constant current of 3.4C from 60% SOC to 65% SOC; Charge at a constant current of 3.1C from 65% SOC to 70% SOC; Charge at a constant current of 2.9C from 70% SOC to 75% SOC; Charge at a constant current of 2.7C from 75% SOC to 80% SOC; Charge at a constant current of 1.8C from 80% SOC to 85% SOC; Charge at a constant current of 1.3C from 85% SOC to 90% SOC; Charge at a constant current of 0.7C from 90% SOC to 95% SOC; Charge at a constant current of 0.33C from 95% SOC to 98% SOC; Charge at a constant current of 0.1C from 98% SOC to 100% SOC.

[0167] The battery cell 10 according to the embodiment of the present application can be charged from 10% SOC to 80% SOC within 10.5 minutes without lithium plating or with slight lithium plating, and has good fast charging ability. Exemplarily, when the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 0.05%, it can be considered that there is no lithium plating. When the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 2% and greater than or equal to 0.05%, it can be considered as slight lithium plating.

[0168] In some embodiments, the pressure relief mechanism 15 includes a weak part 151. The weak part 151 is a part of the pressure relief mechanism 15 with relatively low strength, and it is the part of the pressure relief mechanism 15 that is prone to cracking, breaking, being torn or being opened.

[0169] In some examples, grooves, notches or other structures can be formed in a predetermined area of the pressure relief mechanism 15 of the present application to reduce the local strength of the pressure relief mechanism 15, thereby forming the weak part 151 on the pressure relief mechanism 15. For example, a thinning process is performed on a predetermined area of the pressure relief mechanism 15, and the thinned part of the pressure relief mechanism 15 forms the weak part 151. In other examples, a material treatment can be performed on a predetermined area of the pressure relief mechanism 15 so that the strength of this area is weaker than that of other areas. In other words, this area is the weak part 151.

[0170] 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.

[0171] Exemplarily, the pressure relief mechanism 15 includes a pressure relief part 152, a weak part 151 and a fixing part 153. The weak part 151 is arranged along the outer periphery of the pressure relief part 152 and connects the pressure relief part 152 and the fixing part 153. The fixing part 153 can be used for fixedly connecting to the first end wall 12a.

[0172] Optionally, the weak part 151 surrounds the pressure relief part 152 for one week.

[0173] Optionally, the fixing part 153 is welded to the first end wall 12a.

[0174] In some other embodiments, the pressure relief mechanism 15 and the first end wall 12a are an integrally formed structure. 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.

[0175] Integrally forming the pressure relief mechanism 15 and the first end wall 12a can also eliminate the conventional welding process, reduce the thermal influence on the weak part 151 of the pressure relief mechanism 15, and improve the stability of the pressure relief mechanism 15.

[0176] As an example, a groove, a notch or other structure may be formed on the first end wall 12a to form an annular weak portion 151. The weak portion 151 and the area surrounded by the weak portion 151 constitute a pressure relief mechanism 15.

[0177] As an example, the first end wall 12a may be the bottom wall of the housing 121.

[0178] In some embodiments, the battery 2 further includes a heat exchange member 30 for exchanging heat with the outer shell 12.

[0179] The heat exchange member 30 may be one or more. As an example, the battery cell 10 may exchange heat with only one heat exchange member 30 or may exchange heat with multiple heat exchange members 30 simultaneously.

[0180] The heat exchange member 30 may exchange heat with the outer shell 12 directly or indirectly through other heat conduction structures.

[0181] The heat exchange member 30 may exchange heat with one or more shell walls of the outer shell 12.

[0182] As an example, the heat exchange member 30 may be an independently formed component disposed within the box body 20 or may be integrated with the box body 20.

[0183] The heat exchange member 30 may be an integrally formed component or may be composed of multiple independently formed sub-components spliced together.

[0184] During the charging process of the battery 2, the heat exchange member 30 may exchange heat with the outer shell 12 of the battery cell 10, thereby controlling the temperature of the battery cell 10 within a suitable range, improving the cycling performance of the battery cell 10, reducing the risk of thermal runaway, and enhancing reliability.

[0185] In some embodiments, the outer shell 12 further includes a second end wall 12b and a side wall 12c. The first end wall 12a is disposed opposite to the second end wall 12b. The side wall 12c connects the first end wall 12a and the second end wall 12b and surrounds the electrode assembly 11. The second end wall 12b is fixed to the first box wall 21.

[0186] As an example, the side wall 12c may be a cylindrical structure. For example, if the battery cell 10 is a square shell battery cell, the side wall 12c may be a square cylindrical structure; for example, if the battery cell 10 is a cylindrical battery cell, the side wall 12c is a cylindrical structure.

[0187] The heat exchange member 30 may exchange heat with at least one of the first end wall 12a, the second end wall 12b, and the side wall 12c.

[0188] In some examples, the heat exchange member 30 is integrated with the first box wall 21. For example, a flow channel for the heat exchange medium to flow is provided inside the first box wall 21. The first box wall 21 can exchange heat with the second end wall 12b.

[0189] In other examples, the heat exchange member 30 is located on the lower side of the battery cell 10 and exchanges heat with the first end wall 12a. Optionally, the heat exchange member 30 and the pressure relief mechanism 15 are arranged to avoid each other, so as to reduce the interference of the heat exchange member 30 with the actuation of the pressure relief mechanism 15.

[0190] In some embodiments, the heat exchange member 30 is arranged on the side wall 12c. The heat exchange member 30 is used to exchange heat with the side wall 12c.

[0191] The pressure relief mechanism 15 is arranged on the first end wall 12a, and the second end wall 12b is fixed to the first box wall 21. Arranging the heat exchange member 30 on the side wall 12c can reduce the risk of interference between the heat exchange member 30 and the pressure relief mechanism 15 and save space in the vertical direction Z.

[0192] In some embodiments, the side wall 12c includes two first side walls 12d and two second side walls 12e. The two first side walls 12d are arranged opposite to each other along the thickness direction X of the battery cell 10, and the two second side walls 12e are arranged opposite to each other along the first direction Y perpendicular to the thickness direction X. Each second side wall 12e connects 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.

[0193] In some examples, one first side wall 12d of the battery cell 10 exchanges heat with the heat exchange member 30. Alternatively, the two first side walls 12d of the battery cell 10 respectively exchange heat with the two heat exchange members 30.

[0194] The first side wall 12d is the largest wall of the outer shell 12. Connecting the first side wall 12d to the heat exchange member 30 can increase the heat exchange area, improve the heat exchange efficiency, and further reduce the temperature rise of the battery cell 10 and the risk of thermal runaway and improve the reliability during fast charging.

[0195] In some embodiments, the thickness direction X, the first direction Y, and the vertical direction Z are perpendicular to each other in pairs.

[0196] In some embodiments, the electrode assembly 11 includes a positive electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged between the positive electrode current collectors. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure. One first side wall 12d of the battery cell 10 is connected to the heat exchange member 30.

[0197] The lithium-containing phosphate with olivine structure has excellent cycling stability. By using the lithium-containing phosphate with olivine structure, the heat generation of battery cell 10 during rapid charging can be reduced, and the risk of thermal runaway of battery cell 10 can be lowered. By using the lithium-containing phosphate with olivine structure, the heat exchange requirement can be reduced. In the embodiment of the present application, only one side first side wall 12d of battery cell 10 is connected to heat exchange member 30, which can reduce the number of heat exchange members 30, save space, and improve the energy density of battery 2.

[0198] Of course, in an alternative embodiment, if the capacity of battery 2 meets the requirements, two first side walls 12d of battery cell 10 can also be respectively connected to two heat exchange members 30 to improve the temperature control effect.

[0199] In some embodiments, battery 2 includes a plurality of battery cell groups 100, and each battery cell group 100 includes at least two battery cells 10 arranged along the first direction Y.

[0200] Exemplarily, a plurality of battery cells 10 of battery 2 are arranged in an array in the box body 20.

[0201] The number of battery cells 10 in adjacent battery cell groups 100 may be the same or different.

[0202] In some embodiments, a heat exchange member 30 is provided between every two battery cell groups 100.

[0203] The number of battery cell groups 100 may be even or odd.

[0204] In some examples, the number of battery cell groups 100 is 2n, where n is a positive integer. Along the thickness direction X, a heat exchange member 30 is provided between the (2k - 1)th battery cell group 100 and the 2kth battery cell group 100, and k is a natural number from 1 to n. The number of heat exchange members 30 may be n.

[0205] In other examples, the number of battery cell groups 100 is 2n + 1, where n is a positive integer. Along the thickness direction X, a heat exchange member 30 is provided between the (2k - 1)th battery cell group 100 and the 2kth battery cell group 100, and k is a natural number from 1 to n. The number of heat exchange members 30 may be n + 1, and one heat exchange member 30 may be correspondingly provided for the (2n + 1)th battery cell group 100.

[0206] In the embodiment 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 heat exchange members 30 and improve the space utilization rate and energy density of battery 2.

[0207] In some embodiments, there are multiple heat exchange members 30, and the multiple heat exchange members 30 are arranged along the thickness direction X. Two battery cell groups 100 are provided between adjacent heat exchange members 30.

[0208] In some embodiments, the battery cell group 100 includes m battery cells 10, where 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.

[0209] In some embodiments, the heat exchange member 30 is adhesively bonded to the first side wall 12d through the 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.

[0210] In some embodiments, the first adhesive layer 40 is a thermally conductive adhesive layer.

[0211] In some embodiments, the heat exchange member 30 includes a heat conducting plate 31, and a flow channel 311 for the heat exchange medium to flow through is provided inside the heat conducting plate 31. The heat exchange medium exchanges heat with the battery cell 10 when flowing through the heat conducting plate 31.

[0212] As an example, the heat exchange medium can be a liquid or a gas, such as water.

[0213] In some embodiments, the heat conducting plate 31 is a metal plate or a non-metal plate.

[0214] In some embodiments, the heat exchange member 30 further includes an insulating layer 32, and the insulating layer 32 is disposed on the outer surface of the heat conducting plate 31 and is used to separate the heat conducting plate 31 from the first side wall 12d.

[0215] The insulating layer 32 can insulate the heat conducting plate 31 from the first side wall 12d, increase the creepage distance between the heat conducting plate 31 and the first side wall 12d, and reduce the short-circuit risk.

[0216] In some embodiments, the insulating layer 32 is adhesively bonded to the first adhesive layer 40.

[0217] In some embodiments, the heat conducting plate 31 is made of an insulating non-metal material, and correspondingly, the insulating layer can be omitted.

[0218] 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 ability, thereby improving the heat exchange efficiency.

[0219] In some embodiments, at least a part of the heat exchange member 30 is configured to be deformable in the thickness direction X. The battery cell 10 will expand during the cycling process, and the heat exchange member 30 can be compressed when the battery cell 10 expands, so as to provide space for the expansion of the battery cell 10, reduce the pressure on the electrode assembly 11, and improve the cycling performance of the battery cell 10.

[0220] In some embodiments, the battery 2 further includes a connecting pipe group 50 for connecting a plurality of heat exchange elements 30. The connecting pipe group 50 can communicate with the flow channels 311 of the plurality of heat exchange elements 30, so as to realize the flow of the heat exchange medium in the flow channels 311.

[0221] Exemplarily, the connecting pipe group 50 includes an inlet pipe and an outlet pipe. The inlet pipe communicates with the flow channels 311 of the plurality of heat exchange elements 30, and the outlet pipe communicates with the flow channels 311 of the plurality of heat exchange elements 30.

[0222] 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 both sides of the plurality of battery cells 10. Optionally, the inlet pipe and the outlet pipe are respectively arranged on both sides of the plurality of battery cells 10 along the first direction Y.

[0223] In some embodiments, the battery cell 10 further includes a sampling member 16 disposed on the outer casing 12 for collecting the temperature of the outer casing 12.

[0224] The sampling member 16 can be disposed inside the outer casing 12 or can be disposed inside the outer casing 12.

[0225] The sampling member 16 can collect the temperature of the outer casing 12 in real time, so as to facilitate monitoring and adjusting 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.

[0226] In some embodiments, the sampling member 16 is disposed on the end cap 122.

[0227] In some embodiments, there are a plurality of sampling members 16, and the plurality of sampling members 16 can be disposed at positions where the temperature is relatively high during the cycling of the battery cell 10.

[0228] In some embodiments, the sampling member 16 includes a negative temperature coefficient thermistor.

[0229] In some embodiments, the outer casing 12 is bonded to the first box wall 21 through a second adhesive layer 41. The second adhesive layer 41 can fix the battery cell 10 to the first box wall 21, thereby improving the stability of the battery cell 10. The second adhesive layer 41 is easy to form and is beneficial to simplifying the assembly process.

[0230] In some embodiments, the battery cell 10 further includes a first electrode terminal 13 disposed on the first end wall 12a. The electrode assembly 11 includes an electrode main body 11a and a first tab 11b led out from the electrode main body 11a, and the first electrode terminal 13 is electrically connected to the first tab 11b.

[0231] The first electrode terminal 13 is disposed on the first end wall 12a, which 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 between the outer casing 12 and the first box wall 21, and improve the space utilization rate.

[0232] In some embodiments, the second electrode terminal 14 is also disposed on the first end wall 12a.

[0233] In some embodiments, at least a part of the first electrode terminal 13 is located outside the first end wall 12a.

[0234] The side of the first end wall 12a away from the electrode assembly 11 has an outer surface 1221. Exemplarily, at least a part of the first electrode terminal 13 is located below the plane of the outer surface 1221 of the first end wall 12a.

[0235] In some examples, the first electrode terminal 13 can be entirely located outside the first end wall 12a; alternatively, in some other examples, a part of the first electrode terminal 13 is located outside the first end wall 12a, and another part passes through the first end wall 12a and extends into the outer casing 12.

[0236] The part of the first electrode terminal 13 located outside the first end wall 12a can be used to connect with the busbar component of the battery 2.

[0237] 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 200 mm 2 -600 mm 2 , and can be selected as 200 mm 2 , 250 mm 2 , 300 mm 2 , 350 mm 2 , 400 mm 2 , 450 mm 2 , 500 mm 2 , 550 mm 2 or 600 mm 2 .

[0238] Exemplarily, 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: the projection of the part of the first electrode terminal 13 located outside the first end wall 12a in the vertical direction Z. The vertical direction Z is parallel to the thickness direction of the first end wall 12a.

[0239] The portion of the first electrode terminal 13 located outside the first end wall 12a has a relatively large area, which can increase the over-current area, reduce heat generation, lower the temperature rise of the first electrode terminal 13 during the cycling of the battery 2, and improve reliability. The first electrode terminal 13 has a relatively large exposed area, which can increase the heat dissipation efficiency of the first electrode terminal 13.

[0240] 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 located outside the first end wall 12a is W2 mm. W2 and W1 satisfy: 0.4 ≤ W2 / W1 ≤ 1.

[0241] Optionally, the width direction of the first end wall 12a is parallel to the thickness direction X of the battery cell 10.

[0242] As an example, W2 / W1 is 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0243] Setting W2 / W1 to be greater than or equal to 0.4 can make the first electrode terminal 13 have a relatively large exposed area, increase the connection area between the first electrode terminal 13 and the bus bar component, improve the over-current capacity, reduce the temperature rise, improve the cycling 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 extra space occupied by the first electrode terminal 13 in the width direction and improve the space utilization rate.

[0244] In some embodiments, W2 / W1 is 0.6 - 0.9.

[0245] In some embodiments, the first electrode terminal 13 and the second electrode terminal 14 are arranged at intervals 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.

[0246] 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.

[0247] Figure 6 It is a partial cross-sectional schematic diagram of the battery cell provided in other embodiments of the present application.

[0248] In some embodiments, referring to Figure 6 , the first end wall 12a has an inner surface 1222 facing the electrode assembly 11, and along the direction approaching the electrode assembly 11, the first electrode terminal 13 does not extend beyond the inner surface 1222.

[0249] In the embodiments of the present application, the first electrode terminal 13 may not occupy the internal space of the housing 12, thereby improving the space utilization rate of the battery cell 10 and increasing the energy density of the battery cell 10.

[0250] 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 in the axial direction of the electrode lead-out hole 1223, the first electrode terminal 13 covers the electrode lead-out hole 1223.

[0251] In some embodiments, the battery cell 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 fixedly connected to the first end wall 12a.

[0252] In some embodiments, a part of the second fixing member 18 is embedded in the first fixing member 17.

[0253] In some embodiments, the second fixing member 18 is welded to the first end wall 12a.

[0254] In some embodiments, the first fixing member 17 is an insulating member. The first fixing member 17 is formed by an injection molding process.

[0255] Figure 7 It is a partial cross-sectional schematic view of the battery cell provided in still other embodiments of the present application.

[0256] Referring to Figure 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 passes through the through hole 1311, and a part of the first tab 11b is located on the side of the connecting portion 131 away from the electrode main body 11a and is connected to the connecting portion 131.

[0257] 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 main body 11a, improving the utilization rate of the internal space of the battery cell 10, and increasing the energy density of the battery cell 10.

[0258] 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 a conventional adapter plate and increasing the energy density.

[0259] In some embodiments, the first electrode terminal 13 includes a terminal main body 132 and a cover plate 133. The terminal main body 132 is fixed to the first end wall 12a. The terminal main body 132 includes a connecting portion 131. The cover plate 133 is disposed on the side of the connecting portion 131 away from the electrode main body 11a and is connected to the terminal main body 132. The cover plate 133 separates the through hole 1311 from the external space of the battery cell 10.

[0260] In some embodiments, a recess 134 is provided on a side of the terminal body 132 away from the electrode body 11a, and a connecting portion 131 is provided on the bottom wall of the recess 134. A cover plate 133 is disposed on a side of the connecting portion 131 away from the electrode body 11a and is used to cover the recess 134.

[0261] The recess 134 can accommodate a part of the first tab 11b, thereby improving space utilization. The cover plate 133 separates the external space of the housing 12 from the through hole 1311 to achieve sealing and reduce the risk of electrolyte leakage.

[0262] In some embodiments, at least a part of the cover plate 133 is received in the recess 134. Utilizing the recess 134 to accommodate the cover plate 133 can improve space utilization.

[0263] In some embodiments, the cover plate 133 is welded to the terminal body 132.

[0264] In some embodiments, the cover plate 133 and the first tab 11b are spaced apart to reduce the risk of mutual extrusion between the cover plate 133 and the first tab 11b.

[0265] In some embodiments, the through hole 1311 is a strip-shaped hole that extends along the length direction of the first end wall 12a.

[0266] Figure 8 A cross-sectional view of a battery provided in some embodiments of the present application; Figure 9 is Figure 8 an enlarged view at the circular frame.

[0267] Referring to Figure 8 and Figure 9 , in some embodiments, the box body 20 further includes a second box wall 22, and the second box wall 22 is disposed on the lower side of the battery cell 10 and is disposed opposite to the first box wall 21.

[0268] The second box wall 22 can be a single-layer structure or a multi-layer structure.

[0269] The second box wall 22 can protect the battery cell 10 from the lower side to reduce the risk of the battery cell 10 being impacted by external impurities and improve the reliability of the battery 2.

[0270] 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.

[0271] In some embodiments, the box body 20 further includes 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.

[0272] In some embodiments, the second box wall 22 is spaced apart from the battery cell 10.

[0273] When the battery cell 10 undergoes thermal runaway, the space between the second box wall 22 and the battery cell 10 can serve as an exhaust passage, thereby timely discharging the substances released by the battery cell 10 outside the box body 20 and reducing the explosion risk of the battery 2. When the second box wall 22 is subjected to an 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 and reducing the risk of failure of the battery cell 10, thereby improving the reliability of the battery 2.

[0274] 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 body 20 can be fully utilized, improving the space utilization rate in the vertical direction Z.

[0275] In some embodiments, the battery 2 further includes a support member 60, and the support member 60 is arranged on the lower side of the first end wall 12a and is used to support the first end wall 12a.

[0276] The support member 60 can be one or multiple.

[0277] As an example, the support member 60 can be in contact with the second box wall 22 or can be spaced apart from the second box wall 22.

[0278] The support member 60 can support the battery cell 10, thereby improving the stability of the battery cell 10 and enhancing the overall structural strength of the battery 2.

[0279] In some embodiments, the box body 20 further includes 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 member 60 is bonded to the first end wall 12a and the second box wall 22.

[0280] The support member 60 connects the battery cell 10 and the second box wall 22, thereby enhancing the overall structural strength of the battery 2.

[0281] In some embodiments, third adhesive layers 42 are provided on both sides of the support member 60, and the support member 60 is bonded to the second box wall 22 and the first end wall 12a respectively through the two third adhesive layers 42.

[0282] In some embodiments, the elastic modulus of the support member 60 is less than the elastic modulus of the second box wall 22.

[0283] The elastic modulus of the support member 60 is relatively small. When the second box wall 22 is subjected to an external impact, the support member 60 can deform to reduce the acting force transmitted to the battery cell 10 and reduce the risk of failure of the battery cell 10.

[0284] In some embodiments, the support member 60 has a cavity inside. By providing the cavity, the weight of the support member 60 can be reduced, and the compressibility of the support member 60 can be provided.

[0285] In some embodiments, there are multiple support members 60. The support members 60 extend along the thickness direction X of the battery cell 10, and the multiple support members 60 are arranged at intervals along the first direction Y.

[0286] In some embodiments, both ends of the first end wall 12a along the first direction Y are respectively supported by two support members 60. Exemplarily, in the first direction Y, the first electrode terminal 13, the pressure relief mechanism 15, and the second electrode terminal 14 are arranged between the two support members 60.

[0287] In some embodiments, one support member 60 can support two adjacent battery cells 10 along the first direction Y at the same time.

[0288] In some embodiments, there is a gap between the support member 60 and the heat exchange member 30 in the vertical direction Z.

[0289] Figure 10 A cross-sectional view of a battery provided in some other embodiments of the present application; Figure 11 is Figure 10 An enlarged view at the square box; Figure 12 A cross-sectional view of a support member of a battery provided in some embodiments of the present application; Figure 13 A schematic diagram of an electrode assembly of a battery cell provided in some embodiments of the present application.

[0290] Referring to Figures 10 to 13 , in some embodiments, the box body 20 further includes a plurality of limiting beams 24 connected to the first box 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 provided between adjacent limiting beams 24.

[0291] The limiting beams 24 can be two or more. As an example, a battery cell 10 is provided between any two adjacent limiting beams 24.

[0292] The limiting beams 24 can be used to limit the expansion deformation of the battery cell 10 in the thickness direction X. The limiting beams 24 can directly abut against the battery cell 10 in the thickness direction X; alternatively, other components can also be provided between the limiting beams 24 and the battery cell 10, that is, the limiting beams 24 limit the expansion of the battery cell 10 through this component.

[0293] The limiting beams 24 have high anti-deformation ability, 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 cycling performance of the battery cell 10.

[0294] In some embodiments, an insulating pad 43 is provided between the battery cell 10 and the limiting beam 24.

[0295] In some embodiments, the support member 60 connects adjacent limiting beams 24.

[0296] The support member 60 can be one or multiple.

[0297] The support member 60 can be connected to the limiting beam 24 by welding, snap connection, fastener connection or other connection means.

[0298] The support member 60 is in a strip structure, linear structure, beam structure or other structure. Exemplarily, the support member 60 extends along the thickness direction X of the battery cell 10.

[0299] During the cycling of the battery cell 10, the battery cell 10 expands and exerts a force on the limiting beam 24. The support member 60 can provide a binding force to the limiting beam 24, thereby reducing the deformation of the limiting beam 24, restricting the expansion amount of the battery cell 10, improving the cycling performance of the battery cell 10, and reducing the risk of cracking of the box body 20.

[0300] In some embodiments, the support member 60 can exert a pre-tightening force on the adjacent limiting beams 24.

[0301] In some embodiments, the support member 60 is in a strip structure. The strip structure has low cost and occupies little space; by using the strip-structured support member 60, the space utilization rate inside the battery 2 can be improved, and the energy density of the battery 2 can be increased.

[0302] In some embodiments, the support member 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.

[0303] Exemplarily, the metal strip 61 includes a steel strip.

[0304] The metal strip 61 has high strength, which can not only support the battery cell 10 but also effectively restrain the limiting beam 24. The insulating film 62 can insulate and isolate the metal strip 61 from the battery cell 10, reducing the risk of short circuit.

[0305] In some embodiments, the support member 60 has a cavity 63 inside. By providing the cavity 63, the weight of the support member 60 can be reduced.

[0306] In some embodiments, the metal strip 61 has a cavity 63.

[0307] In some embodiments, the support member 60 is adhesively bonded to the first end wall 12a. The support member 60 being adhesively bonded to the battery cell 10 can increase the connection strength between the battery cell 10 and the battery box 20, reduce the swaying of the battery cell 10 relative to the battery box 20 when the battery 2 is impacted, and improve the reliability and stability of the battery 2.

[0308] In some embodiments, the support member 60 is spaced apart from the second box wall 22 in the vertical direction Z. Alternatively, the support member 60 is adhesively bonded to the second box wall 22.

[0309] In some embodiments, the support member 60 is detachably connected to the limiting beam 24.

[0310] In some embodiments, the connection between the support member 60 and the limiting beam 24 can adopt, but is not limited to, bolt connection, snap connection or other detachable connection methods.

[0311] In some embodiments, the expansion pressure of the battery cell 10 in its own thickness direction X is 0.5 MPa - 2.4 MPa.

[0312] Optionally, the expansion pressure of the battery cell 10 in the thickness direction X is 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa or 2.4 MPa.

[0313] As an example, the expansion pressure of the battery cell 10 can be measured in the following manner: In an ambient temperature of 45°C, discharge the battery cell at a constant current discharge rate of 1C until 2.0V; Clamp the battery cell between two clamping plates, where the two clamping plates are respectively located on both sides of the battery cell along the thickness direction X and cover the large surface (the large surface is the outer surface of the first side wall 12d); In an ambient temperature of 45°C, charge the battery cell at a constant current charge rate of 0.8C until 3.8V, and detect and record the pressure exerted by the battery cell on the clamping plates; Perform cyclic charge and discharge on the battery cell according to the above charge strategy and discharge strategy until the battery cell is cycled to 70% SOH (i.e., the capacity retention rate of the battery cell = the discharge capacity of the battery cell / the nominal capacity of the battery cell = 70%), and record the maximum pressure exerted by the battery cell on the clamping plates; Calculate the expansion pressure Q of the battery cell in the thickness direction as: maximum pressure / large surface area.

[0314] The swelling pressure of the battery cell 10 is related to the compaction degree of the electrode assembly 11. The battery cell 10 has a swelling pressure greater than or equal to 0.5 MPa in the thickness direction X, so as to improve the compaction degree of the electrode assembly 11 and increase the energy density of the battery cell 10. The swelling 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 cycling, reduce the risk of wrinkling deformation of the separator of the electrode assembly 11 and the risk of increased local spacing between the positive electrode sheet and the negative electrode sheet, reduce polarization, and improve the cycling performance of the battery cell 10.

[0315] In the embodiment of the present application, the swelling pressure of the battery cell 10 in the thickness direction X is limited to 0.5 MPa - 2.4 MPa, so as to reduce the swelling deformation of the battery cell 10 during fast charging, improve the cycling performance of the battery cell 10, reduce the risk of cracking of the box body 20, and improve the reliability of the battery 2.

[0316] Limiting the swelling pressure of the battery cell 10 to 1.5 MPa - 2.0 MPa can reduce the requirement for the strength of the limiting beam 24 and reduce the cost.

[0317] In some embodiments, the box body 20 further includes a plurality of limiting beams 24 connected to the first box 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 provided between adjacent limiting beams 24. The distance between adjacent limiting beams 24 in the thickness direction X is D1. In the thickness direction X, the distance between adjacent two limiting beams 24 is D1, and the sum of the sizes of all electrode assemblies 11 stacked along the thickness direction X between adjacent two limiting beams 24 is D2. 85% ≤ D2 / D1 ≤ 92%.

[0318] Exemplarily, between adjacent limiting beams 24, the number of battery cell groups 100 is M 1 . Between adjacent limiting beams 24, the number of battery cells 10 arranged in a row in the thickness direction X is M 1 . Each battery cell 10 includes M 2 electrode assemblies 11.

[0319] When the battery 2 is at 0% SOC, the battery cell 10 is removed and the distance between two limiting beams 24 in the thickness direction X is measured as D1; the removed battery cell 10 is disassembled and the electrode assembly 11 is taken out, and the thicknesses of M 1 ×M 2 electrode assemblies 11 arranged in the thickness direction X are measured and summed to obtain D2.

[0320] Exemplarily, when the battery cell 10 is at % SOC, the size of the electrode assembly 11 in the thickness direction X is T; D2 = M 1 ×M2 ×T.

[0321] 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 rate in the thickness direction X and increase the energy density of the battery 2. Limiting D2 / D1 to 85%-92% can balance the expansion pressure of the battery cell 10 and the energy density of the battery 2 to a certain extent.

[0322] Figure 14 Schematic diagrams of the battery cell and the first busbar component provided by some embodiments of the present application; Figure 15 is Figure 14 schematic diagram of the first busbar component.

[0323] Referring to Figure 14 and Figure 15 In some embodiments, the battery 2 includes a plurality of battery cells 10 and a plurality of busbar components, and the plurality of busbar components electrically connect the plurality of battery cells 10.

[0324] The plurality of busbar components can connect the plurality of battery cells 10 in series, parallel or in a mixed connection.

[0325] The plurality of busbar components can have the same structure or different structures.

[0326] In some embodiments, the plurality of busbar components include at least one first busbar component 70. The first busbar component 70 includes a first busbar layer 71 and a second busbar layer 72 that are stacked and connected. The first busbar layer 71 electrically connects at least two battery cells 10 arranged along the thickness direction X.

[0327] All of the plurality of busbar components can be the first busbar component 70, or some of them can be the first busbar component 70.

[0328] 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 also be independently formed and connected by welding or other means.

[0329] The first busbar component 70 has at least a double-layer structure, and both the first busbar layer 71 and the second busbar layer 72 of the first busbar component 70 can conduct current, so that the first busbar component 70 can have a relatively large current-carrying area, thereby reducing the heat generation of the first busbar component 70, improving the fast charging ability of the battery 2, and reducing the risk of thermal runaway.

[0330] On the premise that the cross-sectional area meets the requirements, the first current collecting component 70 is set as a double-layer structure, which can reduce the requirements for the thickness of the first current collecting layer 71. During the cycling process, the battery cell 10 expands, thereby stretching the first current collecting layer 71. The first current collecting layer 71 has a relatively small thickness and is easy to deform to adapt to the deformation of the battery cell 10, reducing the risk that the connection between the battery cell 10 and the first current collecting layer 71 is torn, and improving the reliability of the battery 2.

[0331] In some embodiments, the thickness of the first current collecting layer 71 is 1 mm - 2.5 mm. Optionally, the thickness of the first current collecting layer 71 is 1.2 mm - 1.8 mm. As an 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. In the embodiments of the present application, the thickness of the first current collecting layer 71 is selected according to the expansion pressure of the battery cell 10, which can balance the current-carrying capacity and deformability of the first current collecting layer 71 to a certain extent, thereby improving the fast charging capacity and reliability of the battery 2.

[0332] In some embodiments, the thickness of the second current collecting layer 72 is 1 mm - 2.5 mm. Optionally, the thickness of the second current collecting layer 72 is 1.2 mm - 1.8 mm. As an 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.

[0333] The thickness of the second current collecting layer 72 can be selected according to the thickness of the first current collecting layer 71 and the current-carrying capacity of the battery for the first current collecting component. Exemplarily, when the thickness of the first current collecting layer 71 is relatively small, the second current collecting layer 72 can have a thickness greater than that of the first current collecting layer 71 to improve the current-carrying capacity of the first current collecting component.

[0334] In some embodiments, the first current collecting layer 71 is connected to the first electrode terminal 13 of one battery cell 10 and the second electrode terminal 14 of another battery cell 10 to connect two battery cells 10 in series. Alternatively, the first current collecting layer 71 is connected to the first electrode terminals 13 of two battery cells 10 to connect two battery cells 10 in parallel.

[0335] In some embodiments, the first current collecting layer 71 is welded to the first electrode terminal 13 and / or the second electrode terminal 14.

[0336] In some embodiments, the first current collecting component 70 includes at least one bending portion 73, and the bending portion 73 connects the first current collecting layer 71 and the second current collecting layer 72.

[0337] The bending portion 73 may be one or multiple.

[0338] The bending portion 73 can connect the first current collecting layer 71 and the second current collecting layer 72, and transmit current between the first current collecting layer 71 and the second current collecting layer 72, thereby improving the current-carrying capacity of the first current collecting component 70.

[0339] In some embodiments, the first current collecting layer 71 includes a first current collecting portion 711, a second current collecting portion 712, and a first buffer portion 713 connecting the first current collecting portion 711 and the second current collecting portion 712. The first current collecting portion 711 and the second current collecting portion 712 are arranged along the thickness direction X and are connected to different battery cells 10.

[0340] Exemplarily, the first current collecting portion 711 can be connected to the electrode terminals (the first electrode terminal 13 or the second electrode terminal 14) of one or more battery cells 10. The second current collecting portion 712 can be connected to the electrode terminals (the first electrode terminal 13 or the second electrode terminal 14) of one or more battery cells 10.

[0341] During the cycling of the battery cell 10, the battery cell 10 expands and applies a pulling force to the first current collecting layer 71; the first buffer portion 713 can release stress through deformation, thereby reducing the stress at the connection between the first current collecting portion 711 and the battery cell 10 and the stress at the connection between the second current collecting portion 712 and the battery cell 10, and reducing the risk of connection failure between the first current collecting layer 71 and the battery cell 10.

[0342] 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.

[0343] In some embodiments, the first buffer portion 713 includes an arched structure.

[0344] In some embodiments, the first current collecting portion 711 is located below the first electrode terminal 13 of one battery cell 10 and is connected to the first electrode terminal 13, and the second current collecting portion 712 is located below the second electrode terminal 14 of another battery cell 10 and is connected to the second electrode terminal 14.

[0345] In some embodiments, the second current collecting layer 72 includes a first stacked portion 721, a second stacked portion 722, and a second buffer portion 723. The first stacked portion 721 is stacked with the first current collecting portion 711 and connected by at least one bending portion 73. The second stacked portion 722 is stacked with the second current collecting portion 712 and connected by at least one bending portion 73. The second buffer portion 723 connects the first stacked portion 721 and the second stacked portion 722.

[0346] Exemplarily, the first stacked portion 721 is attached to the first current collecting portion 711, and the second stacked portion 722 is attached to the second current collecting portion 712.

[0347] During the cycling of the battery 2, a part of the current can be transmitted between the first current collecting portion 711 and the second current collecting portion 712 through the first stacked portion 721, the second buffer portion 723, and the second stacked portion 722, and multiple conductive paths are formed between the first current collecting portion 711 and the second current collecting portion 712, thereby improving the overcurrent capacity.

[0348] During the cycling of the battery cell 10, the battery cell 10 expands and applies a tensile force to the first current collecting layer 71; both the first buffer portion 713 and the second buffer portion 723 can release stress through deformation, thereby reducing the risk of connection failure between the first current collecting layer 71 and the battery cell 10.

[0349] In some embodiments, the second buffer portion 723 at least partially overlaps with the first buffer portion 713, so that the deformation regions of the first buffer portion 713 and the second buffer portion 723 are close, thereby reducing the risk of interference between the first buffer portion 713 and the second buffer portion 723 during deformation with other parts.

[0350] In some embodiments, the second current collecting layer 72 is located on the side of the first current collecting layer 71 away from the battery cell 10.

[0351] In some embodiments, the second current collecting layer 72 is located below the first current collecting layer 71.

[0352] In some embodiments, the multiple current collecting components further include a second current collecting component (not shown) having a single-layer structure. In the battery 2, the expansion amounts of the battery cells 10 at different positions may vary. For the battery cells 10 with a smaller expansion amount, a second current collecting component with a single-layer structure can be used; compared with the first current collecting component 70, the second current collecting component has a simple structure, is easy to manufacture, and can save costs. The thickness of the second current collecting component is greater than the thickness of the first current collecting layer 71 and the second current collecting layer 72, and its overcurrent capacity can meet the requirements.

[0353] Figure 16 An explosion schematic diagram of the battery provided in other embodiments of the present application.

[0354] Refer toFigure 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 vehicle parts, improve the integration of the vehicle, and simplify the assembly process of the vehicle.

[0355] In some embodiments, the battery 2 further includes a mounting beam 80 , which is disposed on a side of the first box wall 21 facing away from the battery cell 10 .

[0356] 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 electrical device, thereby reducing parts, improving integration, and simplifying the assembly process.

[0357] In some embodiments, the mounting beam 80 is used to mount a seat of the vehicle. The embodiment of the present application can improve the space utilization of the entire vehicle. The mounting beam 80 is combined with the first box wall 21 to save more space in the vertical direction Z, thereby further increasing the size of the battery cell 10 along the vertical direction Z and improving the energy density of the battery 2.

[0358] Figure 17 A schematic cross-sectional view of a negative electrode sheet of a battery cell provided in some embodiments of the present application; Figure 18 A schematic cross-sectional view of a negative electrode sheet of a battery cell provided in some other embodiments of the present application; Figure 19 Schematic cross-sectional view of the positive electrode sheet of a battery cell provided in some other embodiments of the present application.

[0359] Reference Figure 13 as well as Figures 17 - 19 In some embodiments, the electrode assembly 11 includes a positive electrode sheet 111, a negative electrode sheet 112, and a separator 113 located between the positive electrode sheet 111 and the negative electrode sheet 112. The positive electrode sheet 111 includes a positive electrode collector 1111 and a positive electrode film layer 1112 disposed between the positive electrode collectors 1111. The positive electrode film layer 1112 includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure. The negative electrode sheet 112 includes a negative electrode collector 1121 and a negative electrode film layer 1122 disposed on at least one side of the negative electrode collector 1121. The negative electrode film layer 1122 includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0360] In the embodiment of the present application, the negative electrode film layer 1122 may be disposed only on one side of the negative electrode current collector 1121 , or may be disposed on both sides of the negative electrode current collector 1121 .

[0361] Optionally, negative electrode current collectors 1121 are provided with negative electrode film layers 1122 on both surfaces opposite to each other in the thickness direction of the negative electrode current collectors themselves. The negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 may use the same negative electrode active material or different negative electrode active materials; the thicknesses of the negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 may be the same or different.

[0362] Exemplarily, the negative electrode current collector 1121 may be a metal foil or a composite current collector. As an example of the metal foil, at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy foils may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0363] The negative electrode active material includes a carbon-based material. The carbon-based material has high cycle stability and can improve the cycle performance of the battery cell 10.

[0364] The positive electrode current collector 1111 has two surfaces opposite to each other in the thickness direction of the positive electrode current collector itself, and the positive electrode film layer 1112 is provided on any one or both of the two opposite surfaces of the positive electrode current collector 1111.

[0365] Exemplarily, the positive electrode current collector 1111 may be a metal foil or a composite current collector. As an example of the metal foil, at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy foils may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0366] The lithium-containing phosphate has high cycle stability. Using the lithium-containing phosphate as the positive electrode active material can improve the cycle attenuation of the battery cell 10 caused by excessive temperature rise during rapid charging.

[0367] In some embodiments, a portion of the negative electrode current collector 1121 is not covered by the negative electrode film layer 1122; the portion of the negative electrode current collector 1121 not covered by the negative electrode film layer 1122 can be used to form a negative electrode tab.

[0368] In some embodiments, the thickness of the negative electrode current collector 1121 is 4 μm to 6 μm. Exemplarily, the thickness of the negative electrode current collector 1121 is 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, or a range composed of any two of the above values.

[0369] In some embodiments, the compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 .

[0370] Exemplarily, at 100% SOC of the battery cell 10, the compaction density of the negative electrode film layer 1122 is 1.15 g / cm 3 、1.18 g / cm 3 、1.20 g / cm 3 、1.22 g / cm 3 、1.25 g / cm 3 、1.28 g / cm 3 、1.3 g / cm 3 、1.32 g / cm 3 、1.35 g / cm 3 、1.36 g / cm 3 or a range composed of any two of the above values.

[0371] Exemplarily, the compaction density of the negative electrode film layer at 100% state of charge of the battery cell 10 has the meaning well known in the art, that is, disassembling the negative electrode sheet from the battery cell at 100% SOC and measuring the compaction density of the negative electrode film layer; for example, taking a single-sided coated negative electrode sheet (if it is a double-sided coated negative electrode sheet, one side of the negative electrode film layer can be wiped off first), punching it into small round pieces with an area of S1, weighing it, recording it as M1, and measuring its thickness H1. Then wipe off the negative electrode film layer of the above weighed negative electrode sheet, weigh the weight of the negative electrode current collector, record it as M0, and measure its thickness H0. The single-sided coating weight of the negative electrode film layer = (the weight M1 of the negative electrode sheet - the weight M0 of the negative electrode current collector) / S1, the thickness of the negative electrode film layer = the thickness H1 of the negative electrode sheet - the thickness H0 of the negative electrode current collector, and the compaction density of the negative electrode film layer = the single-sided coating weight of the negative electrode film layer / the thickness of the negative electrode film layer.

[0372] The compaction density of the negative electrode film layer 1122 is related to the swelling of the battery cell 10 at 100% state of charge. The compaction density of the negative electrode film layer 1122 is limited to 1.15 g / cm 3To 1.36 g / cm 3 , to a certain extent, it can balance the energy density and expansion pressure of the battery cell 10, reduce the deformation of the battery cell 10, and lower the risk of connection failure between the battery cell 10 and the busbar component.

[0373] When the compaction density of the negative electrode film layer 1122 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and since the negative electrode active materials in the negative electrode film layer 1122 are stacked relatively tightly and the contact resistance between particles is small, it can reduce the resistance of the negative electrode sheet 112, thereby reducing heat generation and being beneficial to improving the fast charging ability of the battery 2.

[0374] When the compaction density of the negative electrode film layer 1122 is within the above range, the fast charging ability of the battery cell 10 can be improved. When the compaction density of the negative electrode film layer 1122 is small, the porosity of the negative electrode sheet 112 can be increased, the expansion of the negative electrode sheet can be slowed down, and the expansion pressure of the battery cell 10 can be reduced.

[0375] In some embodiments, the compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.25 g / cm 3 To 1.36 g / cm 3 , which can improve the energy density of the battery cell 10.

[0376] In some embodiments, the single-sided coating weight of the negative electrode film layer 1122 is 90 mg / 1540 mm 2 To 170 mg / 1540 mm 2 . Exemplarily, the single-sided coating weight of the negative electrode film layer 1122 is 90 mg / 1540.25 mm 2 , 92 mg / 1540.25 mm 2 , 95 mg / 1540.25 mm 2 , 96 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 102 mg / 1540.25 mm 2 , 104 mg / 1540.25 mm 2 , 105 mg / 1540.25 mm 2 , 108 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 112 mg / 1540.25 mm 2 , 114 mg / 1540.25 mm 2 , 115 mg / 1540.25 mm 2 , 116 mg / 1540.25 mm 2 , 118 mg / 1540.25 mm2 、120 mg / 1540.25 mm 2 、122 mg / 1540.25 mm 2 、125 mg / 1540.25 mm 2 、128 mg / 1540.25 mm 2 、130 mg / 1540.25 mm 2 、132 mg / 1540.25 mm 2 、135 mg / 1540.25 mm 2 、137 mg / 1540.25 mm 2 、140 mg / 1540.25 mm 2 、142 mg / 1540.25 mm 2 、145 mg / 1540.25 mm 2 、148 mg / 1540.25 mm 2 、150 mg / 1540.25 mm 2 、152 mg / 1540.25 mm 2 、155 mg / 1540.25 mm 2 、160 mg / 1540.25 mm 2 、165 mg / 1540.25 mm 2 、167 mg / 1540.25 mm 2 、170 mg / 1540.25 mm 2 or a range composed of any two of the above values.

[0377] The single-sided coating weight of the negative electrode film layer 1122 is related to the swelling of the negative electrode film layer. The single-sided 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 swelling pressure of the battery cell 10 to a certain extent, reduce the deformation of the battery cell 10, reduce the risk of connection failure between the battery cell 10 and the busbar component, and improve the reliability.

[0378] In addition, the single-sided coating weight of the negative electrode film layer 1122 is limited to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , and can also limit the heat generation of the negative electrode sheet 112 per unit area, reduce the temperature rise of the battery cell 10, especially the temperature rise during fast charging.

[0379] In some embodiments, the single-sided coating weight of the negative electrode film layer 1122 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm2 , so as to further balance the energy density and expansion pressure of the battery cell 10.

[0380] In some embodiments, the porosity of the negative electrode sheet 112 is 27% - 40%. As an example, the porosity of the negative electrode sheet 112 can be 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.

[0381] The porosity of the negative electrode sheet can be the percentage of the pore volume in the negative electrode sheet to the total volume of the negative electrode sheet. Exemplarily, when the battery cell is in a 0% state of charge, a double-sided coated negative electrode sheet is taken; the porosity of the negative electrode sheet is measured by the true density meter AccuPyc Ⅱ1340 in accordance with the national standard GB / T 24586 - 2009.

[0382] 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 the impurities generated by the 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 enhance the reliability of the battery cell 10 during fast charging. 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.

[0383] In some embodiments, the carbon-based material includes graphite particles, and the graphitization degree of the graphite particles is 92.0% to 94.5%. Exemplarily, the graphitization degree of the graphite particles is 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5% or the range composed of any two of the above values.

[0384] When the graphitization degree of the graphite particles is within the above range, the conductive performance of the graphite particles is relatively excellent, which can reduce the heat generation of the negative electrode sheet 112 and the battery cell 10; and can improve the fast charging performance of the battery cell 10.

[0385] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. The artificial graphite and natural graphite have good conductive performance, which can reduce the heat generation of the negative electrode sheet 112 during charging and improve the fast charging performance of the battery cell 10.

[0386] 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.

[0387] In some embodiments, the mass content of silicon element in the silicon-based material in the anode active material is 0.3% to 10%, and optionally 1% to 6%. Exemplarily, the mass content of silicon element in the anode 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 composed of any two of the above values.

[0388] Introducing the silicon-based material into the anode sheet 112 can not only improve the capacity but also increase the expansion of the anode sheet 112. Therefore, limiting the mass content of silicon element in the anode active material to 0.3% to 10% can, to a certain extent, balance the energy density and expansion of the battery cell 10, reduce the deformation of the battery cell 10, and improve the cycle performance and fast charging ability of the battery cell 10.

[0389] In this application, the qualitative and quantitative determination of each substance or element can be carried out by suitable equipment and methods known to those skilled in the art. Relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc. And those skilled in the art can also adaptively change some detection steps / instrument parameters, etc. from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used in combination for qualitative or quantitative determination.

[0390] For example, the silicon-based material can be combined with the general rules of X-ray diffraction analysis method in JIS / K0131-1996 to perform X-ray powder diffraction test and qualitative analysis on the anode sheet or anode active material.

[0391] In some embodiments, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.

[0392] In some embodiments, the silicon-based material includes at least one of silicon oxide compound and silicon-carbon composite.

[0393] In some embodiments, in addition to the carbon-based material and the optional silicon-based material, the anode active material may further include at least one of tin-based material and lithium titanate. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.

[0394] In some embodiments, the negative electrode film layer 1122 in the embodiments of the present application includes at least one film layer. In other words, the negative electrode film layer 1122 can be a single-layer film layer or at least two-layer film layers. Optionally, the negative electrode film layer 1122 includes at least two-layer film layers.

[0395] When the negative electrode film layer 1122 is a single-layer film layer, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. When a single-layer film layer is used, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm to 13.5 μm. Exemplarily, 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 composed of any two of the above values.

[0396] When the negative electrode film layer 1122 is at least two-layer film layers, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. The silicon-based material can be located in one of the at least two-layer film layers or in at least two of the at least two-layer film layers. The negative electrode film layer 1122 can include two-layer film layers, three-layer film layers, four-layer film layers, or even more film layers.

[0397] 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 disposed between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material disposed in the first negative electrode film layer 11221 and a second negative electrode active material disposed in the second negative electrode film layer 11222. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials.

[0398] The interface between the first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be regular or irregular; optionally it is irregular.

[0399] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be differentially set, so as to balance the expansion and capacity of the negative electrode film layer 1122 to a certain extent; double-layer coating can construct the pore difference of the negative electrode film layer 1122, reduce the ion transport tortuosity, reduce side reactions, and improve the fast charging performance of the battery cell 10.

[0400] Artificial graphite can have a relatively small volume average particle size Dv50, which can, on the one hand, shorten the solid-phase transport path of lithium ions and improve the fast-charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material.

[0401] In some embodiments, the ratio of the thickness of the first negative electrode film layer 11221 to the thickness of the second negative electrode film layer 11222 is from 3:7 to 7:3. As an example, the ratio of the thickness of the first negative electrode film layer 11221 to the thickness of the second negative electrode film layer 11222 is 3:7, 4:6, 5:5, 6:4 or 7:3.

[0402] Optionally, the ratio of the thickness of the first negative electrode film layer 11221 to the thickness of the second negative electrode film layer 11222 is from 4:6 to 6:4.

[0403] By adjusting the thickness ratio of the first negative electrode film layer 11221 and the second negative electrode film layer 11222, the gradient pore difference between the upper and lower layers can be further increased, the tortuosity of lithium ion transport can be reduced, and the fast-charging ability of the battery cell 10 can be improved.

[0404] In some embodiments, the thickness of the first negative electrode film layer 11221 is less than or equal to the thickness of the second negative electrode film layer 11222, which can further improve the fast-charging ability of the battery cell 10.

[0405] In some embodiments, the first negative electrode active material is granular, and the second negative electrode active material is granular.

[0406] 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.

[0407] The difference in the particle sizes of the first negative electrode active material and the second negative electrode active material can improve the fast-charging performance of the battery cell 10; during fast charging, the overpotential of the first negative electrode film layer 11221 is usually relatively high, and the bottleneck of fast charging mainly lies in the first negative electrode film layer 11221. In the embodiments of the present application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transport path of ions, improve the fast-charging performance, and can improve the problem of ion precipitation on the surface layer of the negative electrode sheet 112. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer 11222. During charging, the pores can absorb expansion, reduce the expansion amount of the negative electrode film layer 1122, and improve the reliability of the battery cell 10 during fast charging.

[0408] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm - 14.3 μm, and can be optionally 7.8 μm - 11.3 μm. Exemplarily, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm, 8.0 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.3 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, 13.8 μm, 14 μm, 14.1 μm, 14.3 μm or a range composed of any two of the above values.

[0409] The volume average particle size Dv50 of the first negative electrode active material is set to 7.8 μm - 14.3 μm. On the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material; on the further hand, the first negative electrode active material within the above volume average particle size range can cooperate with the second negative electrode active material, which is beneficial to constructing the gradient pore difference between the first negative electrode film layer 11221 and the second negative electrode film layer 11222, reducing the tortuosity of lithium ion transmission, and improving the fast charging performance of the battery cell 10.

[0410] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. It can be detected by using equipment and methods well-known in the art. For example, taking the negative electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E type laser particle size analyzer.

[0411] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, and can be optionally 9.5 - 14.6 μm.

[0412] Exemplarily, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 14.6 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm or a range composed of any two of the above values.

[0413] The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, which can make the pores of the second negative electrode film layer 11222 richer, be beneficial to improving the fast charging ability of the battery cell 10, and reducing the expansion of the negative electrode film layer 1122 during charging.

[0414] In some embodiments, the first negative electrode active material includes graphite particles, and the volume average particle size Dv50 of the graphite particles in the first negative electrode film layer 11221 is 7.8 μm to 14.3 μm, and can be 7.8 μm to 11.3 μm. Optionally, the first negative electrode active material includes artificial graphite.

[0415] The second negative electrode active material includes graphite particles, and the volume average particle size Dv50 of the graphite particles is 9.5 μm to 18.5 μm, and can be 9.5 μm to 14.6 μm. Optionally, the second negative electrode active material includes natural graphite.

[0416] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g, and can be 0.6 m 2 / g - 1.2 m 2 / g. Exemplarily, the specific surface area of the negative electrode active material is 0.5 m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1.0 m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 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 composed of any two of the above values.

[0417] The specific surface area of the material has the meaning well-known in the art and can be detected by devices and methods well-known in the art. For example, it can be detected according to the test standard GB / T 19587-2017. Taking the negative electrode active material as a sample, the specific surface area is tested by a Tri-Star 3020 specific surface area and pore size analyzer of Micromeritics Company in the United States.

[0418] In the embodiments of the present application, the specific surface area of the negative electrode active material is limited to be greater than or equal to 0.5 m 2 / g, which can improve the fast charging ability of the battery cell 10; the specific surface area of the negative electrode active material is limited to be less than or equal to 3 m 2 / g, which can reduce the side reactions during the storage of the battery cell 10, slow down the expansion of the negative electrode sheet, and reduce the expansion pressure.

[0419] In some embodiments, the chemical formula of the lithium-containing phosphate with olivine structure is LiFe 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, and 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.

[0420] In some embodiments, the lithium-containing phosphate with olivine structure or its modified material can be the lithium-containing phosphate with olivine structure or the material obtained after coating modification thereof. For example, the lithium-containing phosphate with olivine structure includes phosphate particles and an ion-conducting layer, and 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.

[0421] In some embodiments, the mass ratio of the lithium-containing phosphate with olivine structure or its modified material in the positive electrode active material can be greater than or equal to 80% and less than or equal to 100%. It can be considered that the positive electrode active material of the present application is a system of the lithium-containing phosphate with olivine structure or its modified material. When the mass ratio of the lithium-containing phosphate with olivine structure or its modified material is less than 100%, the positive electrode active material can also include common positive electrode active materials, such as 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 their respective modified compounds.

[0422] Optionally, the mass ratio of the lithium-containing phosphate with olivine structure or its modified material in the positive electrode active material is 100%.

[0423] In some embodiments, the tap density of the positive electrode film layer 1112 at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 ; optionally 2.55 g / cm 3 -2.70 g / cm 3 . Exemplarily, when the battery cell 10 is at 100% state of charge (SOC), the tap density of the positive electrode film layer 1112 is 2.50 g / cm 3 , 2.52 g / cm 3 , 2.55 g / cm 3 , 2.56 g / cm 3 , 2.57 g / cm 3 , 2.58 g / cm 3 , 2.60 g / cm 3 , 2.62 g / cm 3 , 2.65 g / cm 3 , 2.68 g / cm 3 , 2.30 g / cm 3 , 2.32 g / cm 3 , 2.75 g / cm 3 , 2.78 g / cm 3 , 2.80 g / cm 3 or the range composed of any two of the above values.

[0424] When the tap density of the positive electrode film layer 1112 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and since the positive electrode active materials in the positive electrode film layer 1112 are stacked relatively closely, the contact resistance between particles is small, which can further reduce the resistance of the positive electrode sheet 111, thereby reducing the heat generation during fast charging.

[0425] In the embodiments of the present application, the tap density of the positive electrode film layer 1112 at 100% SOC of the battery cell has the meaning well known in the art, that is, the positive electrode sheet 111 is disassembled from the battery cell 10 at 100% SOC, and the tap density of the positive electrode film layer 1112 is measured. Exemplarily, the test method for the tap density of the positive electrode film layer 1112 can be the same as that for the tap density of the negative electrode film layer 1122.

[0426] In some embodiments, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 ; optionally 240 mg / 1540 mm 2To 330 mg / 1540 mm 2 Exemplarily, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540.25 mm 2 , 210 mg / 1540.25 mm 2 , 220 mg / 1540.25 mm 2 , 230 mg / 1540.25 mm 2 , 240 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 270 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 310 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 330 mg / 1540.25 mm 2 , 340 mg / 1540.25 mm 2 , 350 mg / 1540.25 mm 2 , 360 mg / 1540.25 mm 2 , 370 mg / 1540.25 mm 2 Or a range composed of any two of the above values.

[0427] In the embodiments of the present application, the single-sided coating weight of the positive electrode film layer 1112 has the meaning well-known in the art and can be detected by devices and methods well-known in the art. The detection method is the same as the single-sided coating weight test method of the negative electrode film layer 1122 described above.

[0428] Set the single-sided coating weight of the positive electrode film layer 1112 at 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 , which can limit the heat generation per unit area of the positive electrode sheet 111 and can also take into account the improvement of the energy density and charge rate performance of the battery cell 10.

[0429] In some embodiments, the porosity of the positive electrode sheet 111 is 25% - 32%. As an example, the porosity of the positive electrode sheet 111 can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32% or a range composed of any two of the above values.

[0430] In the embodiments of the present application, the porosity of the positive electrode sheet 111 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. Its detection method is the same as that of the porosity test method of the negative electrode sheet 112.

[0431] The porosity of the positive electrode sheet 111 is greater than or equal to 25%, which can provide space for the impurities generated by side reactions in the positive electrode sheet 111, reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell 10, and improve the cycling performance of the battery cell 10. The porosity of the positive electrode sheet 111 is less than or equal to 32%, which can take into account the energy density of the battery cell 10 to a certain extent.

[0432] In some embodiments, the thickness of the positive electrode sheet 111 can be 0.13 mm - 0.2 mm. As an example, the thickness of the positive electrode sheet 111 can be 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm or the range composed of any two of the above values.

[0433] In the embodiments of the present application, the thickness of the positive electrode sheet 111 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. For example, a micrometer is used to measure the thickness of the positive electrode sheet 111.

[0434] Using the positive electrode sheet 111 with a smaller thickness can shorten the ion migration path, increase the ion migration rate, reduce the heat generation of the battery cell 10, and improve the fast charging performance of the battery cell 10.

[0435] In some embodiments, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05 to 0.3. Exemplarily, in the embodiments of the present application, the thickness of the positive electrode film layer 1112 is the thickness of the positive electrode film layer 1112 on the side of the positive electrode current collector 1111.

[0436] Exemplarily, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3 or the range composed of any two of the above values.

[0437] Defining the ratio of the thickness of the positive current collector 1111 to the thickness of the positive electrode film layer 1112 as greater than or equal to 0.05 can improve the current-carrying capacity of the positive current collector 1111, reduce the temperature rise of the positive electrode sheet 111, and improve the fast charging performance of the battery cell 10; defining the ratio of the thickness of the positive current collector 1111 to the thickness of the positive electrode film layer 1112 as less than or equal to 0.3 can reduce the loss of the capacity of the positive electrode sheet 111. In the embodiments of the present application, defining the ratio of the thickness of the positive current collector 1111 to the thickness of the positive electrode film layer 1112 within 0.05 to 0.3 can balance the fast charging ability and energy density of the battery cell 10 to a certain extent.

[0438] The thickness of the positive electrode film layer and the thickness of the positive current collector have the meanings well-known in the art, and can be detected by using the equipment and methods well-known in the art. For example, the thickness of the positive electrode sheet is measured by a micrometer, the film layer on the surface of the positive current collector is removed, and the thickness of the positive current collector is measured by a micrometer. When the positive electrode film layer is coated on one side, the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive current collector; when the positive electrode film layer is coated on both sides, the thickness of the positive electrode film layer is: (the thickness of the positive electrode sheet minus the thickness of the positive current collector) / 2.

[0439] In some embodiments, the thickness of the positive current collector 1111 is 10 μm to 15 μm, and can be optionally 12 μm to 15 μm. Exemplarily, the thickness of the positive current collector 1111 is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm or the range composed of any two of the above values. When the thickness of the positive current collector 1111 is within the above range, the current-carrying capacity of the positive current collector 1111 is relatively excellent, and the battery cell 10 can have a high energy density.

[0440] In some embodiments, a part of the positive current collector 1111 is not covered by the positive electrode film layer 1112; the part of the positive current collector 1111 not covered by the positive electrode film layer 1112 can be used to form the positive electrode tab.

[0441] In some embodiments, the volume average particle size of the positive active material satisfies 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm.

[0442] Exemplarily, Dv50 of the positive 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 the range composed of any two of the above values.

[0443] Exemplarily, the Dv10 of the positive electrode active material may be 0.4 µm, 0.45 µm, 0.5 µm, 0.55 µm, 0.6 µm, 0.65 µm, 0.7 µm or a range composed of any two of the above values.

[0444] The particle size of the positive electrode active material is relatively small, the lithium deintercalation / insertion path of lithium ions in the positive electrode active material is short, and the heat generation is less; moreover, the particle size of the above positive electrode active material is not too small, which can reduce agglomeration during the processing and preparation process, making the performance of the positive electrode active material stable.

[0445] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. It can be detected by using equipment and methods well-known in the art. For example, taking the positive electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer, etc.

[0446] In some embodiments, the battery cell 10 includes an electrolyte accommodated in the housing 12. During the charge and discharge process of the battery cell 10, active ions are embedded and deintercalated back and forth between the positive electrode plate 111 and the negative electrode plate 112, and the electrolyte plays a role in conducting active ions between the positive electrode plate 111 and the negative electrode plate 112.

[0447] In some embodiments, the conductivity of the electrolyte at room temperature (such as 25 °C) is 13 mS / cm to 20 mS / cm, and can be optionally 15 mS / cm to 20 mS / cm. Exemplarily, the conductivity of the electrolyte at room temperature is 13 mS / cm, 13.5 mS / cm, 14 mS / cm, 14.5 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 16.5 mS / cm, 17 mS / cm, 17.5 mS / cm, 18 mS / cm, 18.5 mS / cm, 19 mS / cm, 19.5 mS / cm, 20 mS / cm or a range composed of any two of the above values.

[0448] When the conductivity of the electrolyte is within the above range, the migration rate of ions in the electrolyte is relatively high, thereby further reducing the internal resistance of the battery cell 10, reducing heat generation, and being able to improve the fast charging performance of the battery cell 10.

[0449] The conductivity of the electrolyte is the ionic conductivity, and it can be detected by using equipment and methods well-known in the art. For example, it is tested with reference to the industry standard HG-T 4067-2015.

[0450] In some embodiments, the density ρ of the electrolyte at room temperature (e.g., 25 °C) satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

[0451] Exemplarily, the density ρ of the electrolyte is 1.05 g / mL, 1.10 g / mL, 1.15 g / mL, 1.2 g / mL, 1.25 g / mL, 1.3 g / mL, 1.35 g / mL or a range composed of any two of the above values.

[0452] When the density ρ of the electrolyte is within the above range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery cell 10, thereby reducing heat generation and improving the fast charging performance of the battery cell 10.

[0453] In the embodiments of the present application, the density of the electrolyte has the meaning well-known in the art and can be detected by devices and methods well-known in the art. For example, it can be tested with reference to GB / T 2013-2010.

[0454] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents.

[0455] In some embodiments, the carboxylate solvent includes a chain carboxylate solvent, and the mass content of the chain carboxylate solvent in the organic solvent is 5% to 75%. Exemplarily, the mass content of the chain carboxylate solvent is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or a range composed of any two of the above values. When the mass content of the chain carboxylate solvent is within the above range, the viscosity of the electrolyte system is relatively small, which is beneficial to the migration of lithium ions.

[0456] In some embodiments, the mass content of the chain carboxylate solvent in the organic solvent is 30% to 70%.

[0457] In some embodiments, the carboxylate includes R 1 -COO-R 2 ,R 1 and R 2 each independently includes an alkyl group with 1-5 carbon atoms or a haloalkyl group with 1-5 carbon atoms. The above chain carboxylate solvents have relatively high conductivity, which is beneficial to improving the fast charging ability of the battery cell 10.

[0458] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

[0459] Further optionally, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0460] The above-mentioned carbonate solvent and the chain carboxylic acid ester solvent are used in combination, which improves the conductivity of the electrolyte and is beneficial to the migration of lithium ions.

[0461] Further optionally, the mass content of the carbonate solvent in the organic solvent is 5% to 95%, optionally 25% to 60%, and optionally 30% to 45%. Exemplarily, the mass content of the carbonate solvent in the organic solvent is 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60% or a range composed of any two of the above values. The carbonate solvent with the above mass content can further improve the conductivity of the electrolyte and is beneficial to the migration of lithium ions.

[0462] Exemplarily, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the mass content of the carbonate solvent is 25% to 60%.

[0463] The combination of organic solvents can improve the conductivity of the electrolyte and reduce the viscosity, thereby improving the fast charging performance of the battery.

[0464] In some embodiments, the electrolyte includes a lithium salt. The lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate LiPF6. The above lithium salts are easy to dissociate, which is beneficial to the rapid migration of lithium ions; and the electrolyte system is relatively stable and not easily decomposed, which can improve the cycle performance of the battery monomer.

[0465] Optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0466] In some embodiments, the lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF 6 , the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is 0.5 mol / L to 1.0 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.4 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is 0.7 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6The molar concentration is 0.5 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is 0.8 mol / L.

[0467] Optionally, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate LiPF 6 is (2 to 5):10. Exemplarily, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate LiPF 6 is 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10, 5:10 or the range composed of any two of the above values.

[0468] According to some embodiments of the present application, the present application further provides an electrical device, including the battery 2 of any one of the above embodiments, and the battery 2 is used to provide electrical energy for the electrical device. The electrical device can be any of the foregoing devices or systems using the battery 2.

[0469] Referring to Figures 2 to 5 , an embodiment of the present application provides a battery 2, which includes a box body 20, a plurality of battery cell groups 100 and a plurality of heat exchange members 30, and the plurality of battery cell groups 100 and the plurality of heat exchange members 30 are accommodated in the box body 20.

[0470] The box body 20 includes 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 are oppositely arranged along the vertical direction Z, the frame 23 connects the first box wall 21 and the second box wall 22, the first box wall 21 is located above the second box wall 22, and the first box wall 21, the second box wall 22 and the frame 23 enclose an accommodation space.

[0471] Each battery cell group 100 includes at least two battery cells 10 arranged along the first direction Y, and the plurality of battery cell groups 100 are arranged along the thickness direction X of the battery cell 10.

[0472] One heat exchange member 30 is provided between every two battery cell groups 100.

[0473] The battery cell 10 includes a housing 12, an electrode assembly 11 and a pressure relief mechanism 15. The housing 12 includes a first end wall 12a, a second end wall 12b and a side wall 12c. The first end wall 12a is located on the side of the electrode assembly 11 facing the second box wall 22, and the first end wall 12a is spaced from the second box wall 22. The second end wall 12b is located on the side of the electrode assembly 11 facing the first box wall 21 and is bonded to the first box wall 21.

[0474] The side wall 12c includes two first side walls 12d and two second side walls 12e. The two first side walls 12d are oppositely arranged along the thickness direction X of the battery cell 10, and the two second side walls 12e are oppositely arranged along the first direction Y perpendicular to the thickness direction X. Each second side wall 12e connects the two first side walls 12d. One of the first side walls 12d of the battery cell 10 is connected to the heat exchange member 30 for heat exchange.

[0475] The pressure relief mechanism 15 is arranged on the first end wall 12a.

[0476] Under room temperature conditions, the charging time for the battery cell 10 to be charged from 10% SOC to 80% SOC can be 5 minutes to 10.5 minutes.

[0477] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0478] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized in that: include: The box body comprises a first box wall; A battery cell is contained in the box body and is located at the lower side of the first box wall. The battery cell includes a shell, an electrode assembly and a pressure relief mechanism. The shell is fixed to the first box wall. The electrode assembly is contained in the shell. The shell includes a first end wall. The first end wall is located at a side of the electrode assembly away from the first box wall. The pressure relief mechanism is arranged on the first end wall. Wherein, under room temperature conditions, the charging time of the battery cell from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes.

2. The battery according to claim 1, characterized in that The pressure relief mechanism and the first end wall are an integrally formed structure.

3. The battery according to claim 1 or 2, characterized in that: A heat exchange element is also included, and the heat exchange element is used for exchanging heat with the shell.

4. The battery according to claim 3, characterized in that The housing further comprises a second end wall and a side wall, the first end wall is arranged opposite to the second end wall, 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 element is arranged on the side wall.

5. The battery according to claim 4, characterized in that 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 of the first side walls of the battery cell is connected to the heat exchange element.

6. The battery according to claim 5, characterized in that The electrode assembly comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer disposed 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 of the first side walls of the battery cell is connected to the heat exchange element.

7. The battery according to claim 5, characterized in that It comprises a plurality of battery cell groups and a plurality of the heat exchange members, wherein the plurality of battery cell groups are arranged along the thickness direction, and each of the battery cell groups comprises at least two battery cells arranged along the first direction; A heat exchange element is provided between every two battery cell groups.

8. The battery according to claim 5, characterized in that The heat exchange element is bonded to the first side wall through a first adhesive layer.

9. The battery according to claim 5, characterized in that The heat exchange element comprises a heat conducting plate, and a flow channel for the heat exchange medium to flow is arranged inside the heat conducting plate.

10. The battery according to claim 9, characterized in that The heat exchange element further includes an insulating layer, which is disposed on the outer surface of the heat conducting plate and is used to separate the heat conducting plate from the first side wall.

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

12. The battery according to claim 1, characterized in that The shell is bonded to the first box wall through a second adhesive layer.

13. The battery according to claim 1, characterized in that The battery cell further includes a first electrode terminal disposed on the first end wall, the electrode assembly includes an electrode body and a first electrode tab extending from the electrode body, and the first electrode terminal is electrically connected to the first electrode tab.

14. The battery according to claim 13, characterized in that The projection area of ​​the portion of the first electrode terminal located outside the first end wall on the first end wall is 200 mm 2 -600mm 2 .

15. The battery according to claim 13 or 14, characterized in that: 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 approaching the electrode assembly.

16. The battery according to claim 13, characterized in that The first electrode terminal includes a connecting portion, the connecting portion is provided with a through hole, the first pole tab is passed through the through hole, and a part of the first pole tab is located on a side of the connecting portion away from the electrode body and connected to the connecting portion.

17. The battery according to claim 16, characterized in that The first electrode terminal comprises a terminal body and a cover plate, the terminal body is fixed to the first end wall, a concave portion is arranged on a side of the terminal body away from the electrode body, and a bottom wall of the concave portion is the connecting portion; The cover plate is arranged on a side of the connecting portion away from the electrode body and is used to cover the recess.

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

19. The battery according to claim 13, characterized in that In the width direction of the first end wall, the size of the first end wall is W1 mm, and the size 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 claim 1, characterized in that The box body further includes a second box wall, which is disposed on the lower side of the battery cell and is opposite to the first box wall.

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

22. The battery according to claim 1, characterized in that A supporting member is also included, and the supporting member is arranged on the lower side of the first end wall and is used to support the first end wall.

23. The battery according to claim 22, characterized in that The box body further comprises a second box wall disposed on the lower side of the battery cell, the second box wall being disposed opposite to the first box wall; The support member is bonded to the first end wall and the second box wall.

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

25. The battery according to claim 22, characterized in that The box body further comprises a plurality of limit beams connected to the first box wall, the plurality of limit beams are arranged at intervals along the thickness direction of the battery monomer, and a plurality of the battery monomers are arranged between adjacent limit beams; The support member connects adjacent limiting beams.

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

27. The battery according to claim 22, characterized in that The support member has a cavity inside.

28. The battery according to claim 1, characterized in that The first box wall is used to serve as at least a part of the floor of the vehicle.

29. The battery according to claim 1, characterized in that It also includes a mounting beam, which is arranged on a side of the first box wall away from the battery cell.

30. The battery according to claim 29, characterized in that The mounting beam is used to mount a seat of a vehicle.

31. The battery according to claim 1, characterized in that The battery cell further includes a sampling component disposed on the shell, and the sampling component is used to collect the temperature of the shell.

32. The battery according to claim 1, characterized in that The expansion pressure of the battery cell in the thickness direction thereof is 0.5 MPa-2.4 MPa.

33. The battery according to claim 1, characterized in that comprising a plurality of the battery cells and a plurality of busbars, wherein the plurality of busbars electrically connect the plurality of the battery cells; The plurality of busbar components include at least one first busbar component including a first busbar layer and a second busbar layer that are stacked and connected, and the first busbar layer electrically connects at least two of the battery cells arranged in a thickness direction.

34. The battery according to claim 33, characterized in that The first busbar component includes at least one bending portion, and the bending portion connects the first busbar layer and the second busbar layer.

35. The battery according to claim 34, characterized in that 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, wherein the first busbar portion and the second busbar portion are arranged along the thickness direction and connected to different battery cells; The second bus layer includes a first stacking portion, a second stacking portion, and a second buffer portion, the first stacking portion is stacked with the first bus portion and connected through at least one bending portion, the second stacking portion is stacked with the second bus portion and connected through at least one bending portion, and the second buffer portion connects the first stacking portion and the second stacking portion.

36. The battery according to claim 1, characterized in that The box body further comprises a plurality of limit beams connected to the first box wall, the plurality of limit beams are arranged at intervals along the thickness direction of the battery monomer, and a plurality of the battery monomers are arranged between adjacent limit beams; In the thickness direction, the distance between two adjacent limiting beams is D1, and the sum of the sizes 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 claim 1, characterized in that The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet includes a positive electrode collector and a positive electrode film layer arranged between the positive electrode collectors, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure, the negative electrode sheet includes a negative electrode collector and a negative electrode film layer arranged on at least one side of the negative electrode collector, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

38. The battery according to claim 37, characterized in that The single-sided coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 Up to 170mg / 1540mm 2 .

39. The battery according to claim 38, characterized in that The single-sided coating weight of the negative electrode film layer is 110 mg / 1540 mm 2 Up to 150mg / 1540mm 2 .

40. The battery according to claim 37, characterized in that The compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 Up to 1.36g / cm 3 .

41. The battery according to claim 40, characterized in that The compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.25 g / cm 3 Up to 1.36g / cm 3 .

42. The battery according to claim 37, characterized in that The porosity of the negative electrode sheet is 27%-40%.

43. The battery according to claim 37, characterized in that The carbon-based material includes at least one of artificial graphite and natural graphite.

44. The battery according to claim 37, characterized in that The negative electrode active material also includes a silicon-based material, and the mass content of silicon in the silicon-based material is 0.3% to 10%.

45. The battery according to claim 44, characterized in that The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% to 6%.

46. ​​The battery according to claim 44, characterized in that The silicon-based material includes at least one of a silicon-oxygen compound and a silicon-carbon composite.

47. The battery according to claim 37, characterized in that The negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer, wherein the second negative electrode film layer is arranged between the first negative electrode film layer and the negative electrode current collector; The negative electrode active material includes a first negative electrode active material arranged in the first negative electrode film layer and a second negative electrode active material arranged in the second negative electrode film layer, the first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite and silicon-based materials.

48. The battery according to claim 47, characterized in that The ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer is 3:7 to 7:

3.

49. The battery according to claim 48, characterized in that The ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer is 4:6 to 6:

4.

50. The battery according to claim 47, characterized in that The thickness of the first negative electrode film layer is less than or equal to the thickness of the second negative electrode film layer.

51. The battery according to claim 47, characterized in that The volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material.

52. The battery according to claim 47, characterized in that The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm.

53. The battery according to claim 52, characterized in that The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-11.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5-14.6 μm.

54. The battery according to claim 37, characterized in that The specific surface area of ​​the negative electrode active material is 0.5 m 2 / g-3m 2 / g.

55. The battery according to claim 54, characterized in that The specific surface area of ​​the negative electrode active material is 0.6 m 2 / g-1.2m 2 / g.

56. The battery according to claim 37, characterized in that The chemical formula of the lithium-containing phosphate with olivine structure is 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.

57. The battery according to claim 37, characterized in that The single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370mg / 1540 / mm 2 .

58. The battery according to claim 57, characterized in that The single-sided coating weight of the positive electrode film layer is 240 mg / 1540 mm 2 Up to 330mg / 1540mm 2 .

59. The battery according to claim 37, characterized in that The compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.50 g / cm 3 Up to 2.80g / cm 3 .

60. The battery according to claim 59, characterized in that The compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.55 g / cm 3 -2.70g / cm 3 .

61. The battery according to claim 37, characterized in that The porosity of the positive electrode sheet is 25%-32%.

62. The battery according to claim 37, characterized in that The thickness of the positive electrode sheet is 0.13mm-0.2mm.

63. The battery according to claim 37, characterized in that 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.

64. The battery according to claim 37, characterized in that The volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm and 0.4µm≤Dv10≤0.7µm.

65. The battery according to claim 1, characterized in that The battery cell includes an electrolyte contained in the housing.

66. The battery according to claim 65, characterized in that The conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm.

67. The battery according to claim 65, characterized in that The electrolyte includes an organic solvent, and the organic solvent includes one or more of a carbonate solvent and a carboxylate solvent.

68. The battery according to claim 67, characterized in that The carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

69. The battery according to claim 67, characterized in that The carboxylic acid ester includes R1-COO-R2, and R1 and R2 each independently include an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms.

70. The battery according to claim 65, characterized in that The electrolyte includes a lithium salt, and the lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. The molar concentration of the lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of the lithium hexafluorophosphate LiPF6 is 0.5 mol / L to 1.0 mol / L.

71. The battery according to claim 65, characterized in that The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL≤ρ≤1.35 g / mL.

72. An electrical device, characterized in that: Comprising a battery according to any one of claims 1-71, wherein the battery is used to provide electrical energy.

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