Battery and electric device

Abstract

The embodiment of the invention provides a battery and an electric device. The battery comprises a box body, a battery monomer and a heat exchange piece, the battery monomer is accommodated in the box body, the battery monomer comprises a shell and an electrode assembly accommodated in the shell, and the shell comprises two first side walls which are oppositely arranged along the thickness direction of the battery monomer; the heat exchange piece is arranged on at least one side of the battery monomer along the thickness direction and is used for exchanging heat with the first side wall. The electrode assembly comprises a positive plate, a negative plate and an isolating membrane located between the positive plate and the negative plate, the positive plate comprises a positive current collector and a positive membrane layer arranged on at least one side of the positive current collector, the positive membrane layer comprises a positive active material, and the positive active material comprises lithium-containing phosphate of an olivine structure. The negative plate comprises a negative current collector and a negative film layer arranged on at least one side of the negative current collector, the negative film layer comprises a negative active material, and the negative active material comprises a carbon-based material.

Description

[0001] This application claims the priority of International Patent Application PCT / CN2024 / 102711 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 a battery and an electrical appliance. Background Art

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

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

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

[0006] In a first aspect, an embodiment of this application provides a battery, which includes a box body, battery cells, and a heat exchange member. The battery cells are accommodated in the box body. The battery cells include an outer shell and an electrode assembly accommodated in the outer shell. The outer shell includes two first side walls oppositely arranged along the thickness direction of the battery cell. The heat exchange member is arranged on at least one side of the battery cell along the thickness direction and is used for heat exchange with the first side walls. The heat exchange member includes a heat conduction plate, and a flow channel is arranged inside the heat conduction plate for arranging a heat exchange medium; the battery further includes a support member, which is arranged on the lower side of the outer shell and is used for supporting the outer shell; the box body includes a plurality of limiting beams, the plurality of limiting beams are arranged at intervals along the thickness direction of the battery cell, and a plurality of battery cells are arranged between adjacent limiting beams; 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 arranged on at least one side of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material 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 arranged on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0007] The first side wall can be the largest wall of the outer shell. Exchanging heat between the first side wall and the heat exchanger can improve the heat exchange efficiency. Furthermore, during fast charging, the temperature rise of the battery cell can be reduced, the cycle performance and cycle life of the battery cell can be improved, the risk of thermal runaway can be reduced, and the reliability can be enhanced. The carbon-based material and the lithium-containing phosphate have relatively high cycle stability. Using the lithium-containing phosphate as the positive electrode active material and the carbon-based material as the negative electrode active material can improve the cycle attenuation of the battery cell caused by the temperature rise during fast charging and enhance the cycle performance of the battery cell. In the embodiments of the present application, the carbon-based material and the lithium-containing phosphate are used as the negative electrode active material and the positive electrode active material respectively, and combined with the heat exchange between the first side wall and the heat exchanger, the fast charging ability of the battery cell can be improved, the influence of heat generation during fast charging on the cycle performance of the battery cell can be reduced, the charging time can be saved, and the user experience can be improved.

[0008] In some embodiments, at room temperature, the charging time of the battery cell from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes. The battery cell 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 cell, the heat exchanger can exchange heat with the first side wall to reduce the temperature rise of the battery cell during fast charging; the carbon-based material and the lithium-containing phosphate have relatively high cycle stability, which can improve the cycle attenuation of the battery cell caused by the temperature rise during fast charging.

[0009] In some embodiments, one first side wall of the battery cell is connected to the heat exchanger. The lithium-containing phosphate with olivine structure has relatively excellent cycle stability. Using the lithium-containing phosphate with olivine structure can reduce the heat generation of the battery cell during fast charging and reduce the risk of thermal runaway of the battery cell. Using the lithium-containing phosphate with olivine structure can reduce the heat exchange requirement. In the embodiments of the present application, connecting one first side wall of the battery cell to the heat exchanger can reduce the number of heat exchangers, save space, and improve the energy density of the battery.

[0010] 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 along the thickness direction, and each battery cell group includes at least two battery cells arranged along the direction perpendicular to the thickness direction. One heat exchanger is provided between every two battery cell groups. One heat exchanger can exchange heat with the battery cells of two battery cell groups at the same time, which can reduce the number of heat exchangers, improve the space utilization rate and energy density of the battery.

[0011] In some embodiments, the heat exchanger is bonded to the first side wall through a first adhesive layer. The first adhesive layer can stably connect the heat exchanger to the first side wall to improve the stability of heat exchange between the heat exchanger and the battery cell.

[0012] In some embodiments, the heat exchange member includes a heat conducting plate, and a flow channel is provided inside the heat conducting plate for arranging a heat exchange medium. The flow channel can guide the heat exchange medium to flow, so that the heat exchange medium exchanges heat with the battery cell when flowing through the heat conducting plate.

[0013] In some embodiments, the heat exchange member further includes an insulating layer, and at least a part of the insulating layer is arranged between the heat conducting plate and 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.

[0014] 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, thus improving the heat exchange efficiency.

[0015] In some embodiments, the housing further includes a first end wall and a second end wall which are oppositely arranged, and the first side wall connects the first end wall and the second end wall. The first end wall is located below the electrode assembly, and the second end wall is located above the electrode assembly and connected to the box body. Fixing the second end wall to the box body can save the space above the battery cell and improve the space utilization rate.

[0016] In some embodiments, the second end wall is bonded to the box body, thereby enhancing the stability of the battery.

[0017] In some embodiments, the battery cell further includes a pressure relief mechanism arranged on the first end wall. During the rapid charging process of the battery, even if the battery cell experiences thermal runaway accidentally, the high - temperature substances generated by the battery cell can be ejected downward through the pressure relief mechanism, thereby reducing the thermal influence on the upper side of the battery, reducing the risk of user injury, and improving the reliability of the battery and the electrical device using the battery.

[0018] In some embodiments, the housing further includes a first end wall, and the first end wall connects two first side walls. The battery cell further includes a first electrode terminal arranged on the first end wall; the electrode assembly includes an electrode body and a first tab led out from the electrode body, and the first electrode terminal is electrically connected to the first tab. Arranging the first electrode terminal on the first end wall can reduce the risk of interference between the first electrode terminal and the heat exchange member and improve the heat exchange efficiency.

[0019] 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 relatively large area, which can increase the current - carrying area, reduce heat generation, reduce the temperature rise of the first electrode terminal during the battery cycle, and improve the reliability. The first electrode terminal has a relatively large exposed area, which can increase the heat dissipation efficiency of the first electrode terminal.

[0020] 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 avoid occupying the internal space of the housing, thereby improving the space utilization rate of the battery cell and enhancing the energy density of the battery cell.

[0021] 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 internal space utilization rate of the battery cell, and increasing the energy density of the battery cell.

[0022] 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.

[0023] In some embodiments, at least a part of the cover plate is received in the recess. Utilizing the recess to accommodate the cover plate can improve the space utilization rate.

[0024] 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.

[0025] 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 busbar component, enhance 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.

[0026] In some embodiments, the box body includes a first box wall located on the upper side of the battery cell, and the battery cell is fixed to the first box wall. The embodiments of the present application can save the space on the upper side of the battery cell and improve the space utilization rate.

[0027] In some embodiments, the first box wall is used as at least a part of the floor of the vehicle. Using the first box wall as the floor can save vehicle components, improve the vehicle integration, and simplify the vehicle assembly process.

[0028] In some embodiments, the battery further includes a mounting beam disposed on a side of the first box wall away from the battery cell, which can enhance the overall strength of the battery. The mounting beam can also provide mounting positions for some components of the electrical device, thereby reducing the number of components, improving the integration level, and simplifying the assembly process.

[0029] 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 overall vehicle utilization rate.

[0030] In some embodiments, the box body includes a second box wall disposed on the lower side of the battery cell. 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.

[0031] In some embodiments, the second box wall is spaced apart from the battery cell. When the battery cell undergoes thermal runaway, the space between the second box wall and the battery cell can serve as an exhaust channel, thereby timely discharging the substances released by the battery cell outside the box body and reducing 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.

[0032] In some embodiments, the battery further includes a support member disposed on the lower side of the outer shell and used to support the outer shell. 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.

[0033] In some embodiments, the box body includes a second box wall disposed on the lower side of the battery cell. The support member is bonded to the outer shell and the second box wall. The support member connects the battery cell and the second box wall, thereby enhancing the overall structural strength of the battery.

[0034] In some embodiments, the elastic modulus of the support member is less than that of the second box wall. Since the elastic modulus of the support member is small, when the second box wall is subjected to an external impact, the support member can deform to reduce the acting force transmitted to the battery cell and reduce the risk of battery cell failure.

[0035] In some embodiments, the box body includes a plurality of limiting beams spaced apart along the thickness direction of the battery cell, and a plurality of battery cells are disposed between adjacent limiting beams. The support member connects adjacent limiting beams.

[0036] The limiting beam has a high anti-deformation ability and can effectively constrain the battery cell in the thickness direction; the support member can provide a binding force to the limiting beam, thereby reducing the deformation of the limiting beam and restricting the expansion amount of the battery cell, improving the cycling performance of the battery cell, and reducing the risk of box body cracking.

[0037] 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 restrain the limiting beam. The insulating film can insulate the metal strip from the battery cell, reducing the risk of short circuit.

[0038] In some embodiments, the support member has a cavity inside. By providing the cavity, the weight of the support member can be reduced.

[0039] 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 monitor and adjust the temperature of the battery cell, reduce the risk of abnormal temperature rise of the battery cell during fast charging, and improve the reliability of the battery.

[0040] In some embodiments, the expansion pressure of the battery cell in its own thickness direction is 0.5 MPa - 2.4 MPa. The expansion pressure of the battery cell in the thickness direction is limited to 0.5 MPa - 2.4 MPa to reduce the expansion deformation of the battery cell during fast charging, improve the cycle performance of the battery cell, reduce the risk of box body cracking, and enhance the reliability of the battery.

[0041] 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.

[0042] 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 fast 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 of the battery cell, expansion occurs, which stretches 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 of the connection between the battery cell and the first busbar layer being torn, and enhancing the reliability of the battery.

[0043] 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.

[0044] 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, and the second stacked portion is stacked with the second current collecting portion and connected through at least one bending portion.

[0045] 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, and 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.

[0046] In some embodiments, the box body includes a plurality of limiting beams, the plurality of limiting beams are arranged at intervals along the thickness direction of the battery cell, and a plurality of battery cells are arranged between adjacent limiting beams. 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%.

[0047] 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 fast 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 to 85% - 92% can balance the expansion pressure of the battery cell and the energy density of the battery to a certain extent.

[0048] 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 can 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 amount of the negative electrode sheet per unit area, reduce the temperature rise of the battery cell, especially the temperature rise during fast charging.

[0049] In some embodiments, the compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 , and can be optionally 1.25 g / cm3 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, the contact resistance between particles is small, which can reduce the resistance of the negative electrode sheet, thereby reducing heat generation and being beneficial to improving the fast charging ability of the battery.

[0050] In some embodiments, the porosity of the negative electrode sheet is 27% - 40%.

[0051] 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 swelling of the negative electrode sheet, reduce the swelling pressure of the battery cell, reduce the deformation of the battery cell, improve the cycling performance of the battery cell, and improve the reliability of the battery cell during fast 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.

[0052] 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 electrical conductivity, can reduce heat generation during charging of the negative electrode sheet, and improve the fast charging performance of the battery cell.

[0053] 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 can be selected from 1% to 6%.

[0054] Introducing a silicon-based material into the negative electrode sheet can not only increase the capacity but also increase the swelling of the negative electrode sheet. Therefore, limiting the mass content of silicon element in the negative electrode active material to 0.3% to 10% can, to a certain extent, take into account the energy density and swelling of the battery cell, reduce the deformation of the battery cell, and improve the cycling performance and fast charging ability of the battery cell.

[0055] In some embodiments, the silicon-based material includes at least one of silicon oxide compounds and silicon-carbon composites.

[0056] 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.

[0057] The first negative electrode film layer and the second negative electrode film layer can be set differently, so as to balance the expansion and capacity of the negative electrode film layer to a certain extent; double-layer coating can construct the pore difference of the negative electrode film layer, reduce the ion transport tortuosity, reduce side reactions, and improve the fast charging performance of the battery cell.

[0058] In some embodiments, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer is 3:7 to 7:3, and 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.

[0059] 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.

[0060] 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 negative electrode active material.

[0061] There are differences in the particle sizes of the first negative electrode active material and the second negative electrode active material, which can improve the fast charging performance of the battery cell; during fast charging, the overpotential of the first negative electrode film layer is usually relatively high, and the bottleneck of fast charging mainly lies in the first negative electrode film layer. In the embodiments of the present application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transport path of ions, improve the fast charging performance, and can improve the problem of ion precipitation on the surface layer of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer. During charging, the pores can absorb expansion, reduce the expansion amount of the negative electrode film layer, and improve the reliability of the battery cell during fast charging.

[0062] 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.

[0063] The volume average particle size Dv50 of the first negative electrode active material is set within the above range. On the one hand, it can shorten the solid-phase transport path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material; on the other hand, the first negative electrode active material within the above volume average particle size range can cooperate with the second negative electrode active material, which is beneficial to constructing the gradient pore difference between the first negative electrode film layer and the second negative electrode film layer, reducing the lithium ion transport tortuosity, and improving the fast charging performance of the battery cell.

[0064] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, and may be optionally 9.5 μm - 14.6 μm. Setting the volume average particle size Dv50 of the second negative electrode active material within the above range can make the pores of the second negative electrode film layer richer, which is beneficial to improving the fast charging ability of the battery cell and reducing the swelling of the negative electrode film layer during charging.

[0065] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g, and may be optionally 0.6 m 2 / g - 1.2 m 2 / g. Limiting the specific surface area of the negative electrode active material to be greater than or equal to 0.5 m 2 / g can improve the fast charging ability of the battery cell; limiting the specific surface area of the negative electrode active material to be less than or equal to 3 m 2 / g can reduce the side reactions during the storage of the battery cell and reduce the swelling pressure.

[0066] In some embodiments, the chemical formula of the lithium-containing phosphate with an olivine structure is LiFe 1-x-y Mn x M y PO 4 , where 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, Hf, Ta, Mo, W, Ru, Ag, Sn, and Pb.

[0067] In some embodiments, the single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 ; and may be optionally 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2 . Setting the single-sided coating weight of the positive electrode film layer within the above range can limit the heat generation per unit area of the positive electrode sheet and can take into account improving the energy density and charging rate performance of the battery cell.

[0068] In some embodiments, the compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 ; and may be optionally 2.55 g / cm 3 -2.70 g / cm 3When 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 relatively tightly, the contact resistance between particles is small, which can further reduce the resistance of the positive electrode sheet, thereby reducing heat generation during fast charging.

[0069] 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 cycling performance of the battery cell. When the porosity of the positive electrode sheet is less than or equal to 32%, the energy density of the battery cell can be taken into account to a certain extent.

[0070] 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 heat generation of the battery cell, and improve the fast charging performance of the battery cell.

[0071] In some embodiments, the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer is 0.05 - 0.3. Limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be greater than or equal to 0.05 can improve the current-carrying capacity of the positive electrode current collector, reduce the temperature rise of the positive electrode sheet, and improve the fast charging performance of the battery cell; limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be less than or equal to 0.3 can reduce the loss of the capacity of the positive electrode sheet. In the embodiments of the present application, limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to be between 0.05 and 0.3 can take into account the fast charging ability and energy density of the battery cell to a certain extent.

[0072] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm. The particle size of the positive electrode active material is relatively small, the lithium insertion / extraction 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.

[0073] 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 inserted and extracted 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.

[0074] In some embodiments, the conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm. When the conductivity of the electrolyte is within the above range, the migration rate of ions in the electrolyte is relatively high, thereby further reducing the internal resistance of the battery cell, reducing heat generation, and improving the fast charging performance of the battery cell.

[0075] 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.

[0076] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0077] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 each independently include an alkyl group having 1 to 5 carbon atoms or a haloalkyl group having 1 to 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.

[0078] In some embodiments, the electrolyte includes a lithium salt, and 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. 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.

[0079] 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.

[0080] 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

[0081] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0082] Figure 1 Schematic diagram of the structure of a vehicle provided for some embodiments of the present application; Figure 2 Explosion diagram of a battery provided for some embodiments of the present application; Figure 3 Explosion diagram of a battery cell provided for some embodiments of the present application; Figure 4 For Figure 2 Enlarged schematic diagram at the circular frame; Figure 5 Partial sectional view schematic diagram of a battery provided for some embodiments of the present application; Figure 6 Sectional view schematic diagram of the electrode assembly of a battery cell provided for some embodiments of the present application; Figure 7 Schematic diagram of the negative electrode sheet of a battery cell provided for some embodiments of the present application; Figure 8 Schematic diagram of the positive electrode sheet of a battery cell provided for some embodiments of the present application; Figure 9 Partial sectional view schematic diagram of a battery cell provided for other embodiments of the present application; Figure 10 Partial sectional view schematic diagram of a battery cell provided for yet other embodiments of the present application; Figure 11 Sectional view schematic diagram of a battery provided for some embodiments of the present application; Figure 12 For Figure 11 Enlarged schematic diagram at the circular frame; Figure 13 Sectional view schematic diagram of a battery provided for other embodiments of the present application; Figure 14 For Figure 13 Enlarged schematic diagram at the square frame; Figure 15 Sectional view schematic diagram of the support member of a battery provided for some embodiments of the present application; Figure 16 Schematic diagram of a battery cell and a first busbar component provided for some embodiments of the present application; Figure 17 For Figure 16 Schematic diagram of the first busbar component; Figure 18 Explosion diagram of a battery provided for other embodiments of the present application; Figure 19 Sectional view schematic diagram of the negative electrode sheet of a battery cell provided for other embodiments of the present application.

[0083] The description of the 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 plate; 1111. Positive current collector; 1112. Positive electrode film layer; 112. Negative electrode plate; 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 cover; 1221. Outer surface; 1222. Inner surface; 1223. Electrode lead-out hole; 12a. First end wall; 12b. Second end wall; 12c. Side wall; 12d. First side wall; 12e. Second side wall; 13. First electrode terminal; 131. Connection part; 1311. Through hole; 132. Terminal body; 133. Cover plate; 134. Recess; 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. Box body; 21. First box wall; 22. Second box wall; 23. Frame; 24. Limiting beam; 30. Heat exchange part; 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 part; 61. Metal strip; 62. Insulating film; 63. Cavity; 70. First busbar component; 71. First busbar layer; 711. First busbar part; 712. Second busbar part; 713. First buffer part; 72. Second busbar layer; 721. First stacked part; 722. Second stacked part; 723. Second buffer part; 73. Bent part; 80. Installation beam; X. Thickness direction; Y. First direction; Z. Vertical direction. Detailed implementation manners

[0084] In the following, for the purpose of making 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. Obviously, 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 shall fall within the scope of protection of the present application.

[0085] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled 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.

[0086] Referring to "embodiments" in the present application means that 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 at 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.

[0087] In the description of the present application, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" and "attached" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, and it can 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 situations.

[0088] The term "and / or" in the present application is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: 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.

[0089] 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 thickness, length, width and other dimensions of various components shown in the drawings in the embodiments of the present application, as well as the overall thickness, length, width and other dimensions of the integrated device are only for illustrative purposes and should not constitute any limitation to the present application.

[0090] The "ranges" disclosed in this application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include or exclude 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 this application, unless otherwise stated, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0091] The term "a plurality of" as used in this application means two or more (including two).

[0092] Currently, judging from the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only applied to energy storage power systems such as hydraulic, thermal, wind, and solar power stations, but also widely used in electric transportation such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as aerospace. With the continuous expansion of the battery application field, the market demand is also constantly increasing.

[0093] A battery generally refers to a single physical module that includes a plurality of battery cells to provide a higher voltage and capacity. A battery cell can be the smallest unit that makes up a battery.

[0094] With the development of batteries, especially their widespread use 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 rapid 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, affecting the cycle performance and cycle life of the battery, and increasing the risk of battery thermal runaway.

[0095] In view of this, an embodiment of the present application provides a battery. By providing a heat exchange member and exchanging heat between the heat exchange member and the side wall with a larger area of the battery cell, the heat exchange efficiency is improved, the risk of thermal runaway of the battery cell during rapid charging is reduced, the temperature rise of the battery cell is reduced, and the cycle performance and cycle life of the battery cell are improved.

[0096] 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, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, and the like. Among them, the electric toy can include fixed or mobile electric toys, such as a game console, an electric vehicle toy, an electric ship toy, and an electric aircraft toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, and a spaceship, etc.

[0097] For the convenience of description, the following embodiments will be described by taking the electrical device as a vehicle as an example.

[0098] Figure 1 It is a schematic structural diagram of a vehicle provided by some embodiments of the present application.

[0099] 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 an operating power source of the vehicle 1.

[0100] 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.

[0101] In some embodiments of the present application, the battery 2 can not only be used as an operating power source of the vehicle 1, but also be used as a driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0102] Figure 2 It is a schematic diagram of a battery provided by some embodiments of the present application.

[0103] Referring to Figure 2 , in some embodiments, the battery 2 includes a box body 20 and a plurality of battery cells 10 accommodated in the box body 20.

[0104] The battery cell 10 can be a secondary battery. A secondary battery refers to a battery cell that can be activated by charging after the battery cell discharges and can continue to be used.

[0105] 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.

[0106] As an example, the battery cell 10 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc.

[0107] Multiple battery cells 10 can be connected in series, in parallel or in a combined series-parallel manner. The combined series-parallel connection means that there are both series and parallel connections among multiple battery cells 10. Multiple battery cells 10 can be directly connected in series, in parallel or in a combined series-parallel manner and then the whole formed by multiple battery cells 10 is accommodated in the box body 20. Of course, it can also be that multiple battery cells 10 are first connected in series, in parallel or in a combined series-parallel manner to form battery modules, and then multiple battery modules are connected in series, in parallel or in a combined series-parallel manner to form a whole and are accommodated in the box body 20.

[0108] In some embodiments, the battery 2 includes multiple busbar components, and the multiple busbar components connect multiple battery cells 10 in series, in parallel or in a combined series-parallel manner.

[0109] In some embodiments, the box body 20 can be a part of the chassis structure of a vehicle. For example, a part of the box body 20 can become at least a part of the floor of the vehicle, or a part of the box body 20 can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0110] Figure 3 It is an exploded view of the battery cell provided in some embodiments of the present application.

[0111] Referring to Figure 3 , in some embodiments, the battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12.

[0112] The housing 12 is a hollow structure, and an accommodation space for accommodating the electrode assembly 11 and the electrolyte is formed inside it. The shape of the housing 12 can be determined according to the specific shape of the electrode assembly 11. For example, if the electrode assembly 11 is a cuboid structure, a cuboid housing can be selected.

[0113] As an example, the housing 12 includes a shell 121 and an end cap 122. The shell 121 has an opening, and the end cap 122 is used to cover the opening.

[0114] The shell 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.

[0115] 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.

[0116] 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, for example, copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not make special restrictions on this.

[0117] 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 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 or collided, so that the battery cell 10 can have higher structural strength and the reliability can also be improved.

[0118] The end cap 122 is connected to the housing 121 by welding, bonding, clamping or other means.

[0119] One end of the housing 121 can be open, or both ends can be open. In some examples, the housing 121 can be a structure with one side open, and the end cap 122 is provided as one and covers the housing 121. In other examples, the housing 121 can also be a structure with both sides open, and the end cap 122 is provided as two, and the two end caps 122 respectively cover the two openings of the housing 121.

[0120] The electrode assembly 11 is the component in the battery cell 10 where the electrochemical reaction occurs. One or more electrode assemblies 11 can be included in the housing 121.

[0121] In some embodiments, the electrode assembly 11 includes a positive electrode plate and a negative electrode plate. During the charge and discharge process of the battery cell 10, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate.

[0122] In some embodiments, the electrode assembly 11 further includes a separator, which is disposed between the positive electrode plate and the negative electrode plate, and can play a role in preventing short circuit between the positive and negative electrodes, and at the same time can allow active ions to pass through.

[0123] 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 extend 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.

[0124] As an example, the portion of the positive electrode sheet having the active material, the portion of the negative electrode sheet having the active material, and the separator form the electrode assembly 11. The portion of the positive electrode sheet without the active material forms the positive tab, and the portion of the negative electrode sheet without the active material forms 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.

[0125] In some embodiments, the electrode assembly 11 is in a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0126] In some embodiments, the electrode assembly 11 is in a stacked structure.

[0127] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets are alternately stacked.

[0128] As an example, multiple positive electrode sheets can be provided, and the negative electrode sheet is folded to form multiple stacked folding segments, and a positive electrode sheet is clamped between adjacent folding segments.

[0129] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form multiple stacked folding segments.

[0130] As an example, multiple separators can be provided and are respectively disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0131] As an example, the separator can be continuously provided and is disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0132] 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.

[0133] The first electrode terminal 13 and the second electrode terminal 14 are used for electrical connection with an external circuit to achieve charging or discharging of the battery cell 10.

[0134] 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.

[0135] 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 part of the housing 12.

[0136] In some embodiments, both the first electrode terminal 13 and the second electrode terminal 14 are disposed on the end cap 122.

[0137] 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, overcharge 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.

[0138] 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.

[0139] The pressure relief mechanism 15 can be in the form of, for example, an explosion-proof valve, air valve, pressure relief valve or 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 releasing the internal pressure. 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 releasing the internal pressure.

[0140] During thermal runaway of the battery cell 10, 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.

[0141] In some embodiments, the pressure relief mechanism 15 is disposed on the housing 12. Exemplarily, the pressure relief mechanism 15 can be disposed on the housing body 121 or on the end cap 122.

[0142] Figure 4 For Figure 2 An enlarged schematic view at the round frame; Figure 5 A partial cross-sectional schematic view of a battery provided in some embodiments of the present application; Figure 6 A cross-sectional schematic view of an electrode assembly of a battery cell provided in some embodiments of the present application; Figure 7 A schematic view of a negative electrode plate of a battery cell provided in some embodiments of the present application; Figure 8Schematic diagram of the positive electrode sheet of the battery cell provided by some embodiments of the present application.

[0143] Referring to Figures 2 to 8 , embodiments of the present application provide a battery 2, which includes a battery cell 10, a box body 20, and a heat exchange member 30.

[0144] The battery cell 10 is accommodated in the box body 20. The battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12. The housing 12 includes two first side walls 12d oppositely arranged along the thickness direction X of the battery cell 10.

[0145] The heat exchange member 30 is disposed on at least one side of the battery cell 10 along the thickness direction X and is used for heat exchange with the first side wall 12d.

[0146] 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 current collector 1111 and a positive electrode film layer 1112 disposed on at least one side of the positive electrode current collector 1111. The positive electrode film layer 1112 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 current collector 1121 and a negative electrode film layer 1122 disposed on at least one side of the negative electrode current collector 1121. The negative electrode film layer 1122 includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0147] As an example, there are multiple battery cells 10.

[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] 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.

[0151] The heat exchange member 30 may directly contact the first side wall 12d for heat exchange or may indirectly exchange heat with the housing 12 through other heat conduction structures.

[0152] 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 two heat exchange members 30.

[0153] The heat exchange member 30 may be an integrally formed component or may be composed of multiple independently formed sub-components spliced together.

[0154] In the embodiments of the present application, the negative electrode film layer 1122 may be provided on only one side of the negative electrode current collector 1121, or the negative electrode film layer 1122 may be provided on both sides of the negative electrode current collector 1121.

[0155] Optionally, the negative electrode film layer 1122 is provided on both surfaces of the negative electrode current collector 1121 that are opposite to each other in the thickness direction of the negative electrode current collector 1121. The negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 may 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.

[0156] 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).

[0157] 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.

[0158] The positive electrode current collector 1111 has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer 1112 is provided on any one or both of the two opposite surfaces of the positive electrode current collector 1111.

[0159] 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).

[0160] In the embodiment of the present application, the first side wall 12d can be the largest shell wall of the outer shell 12. The heat exchange between the first side wall 12d and the heat exchange element 30 can improve the heat exchange efficiency, thereby reducing the temperature rise of the battery cell 10 during fast charging, improving the cycle performance and cycle life of the battery cell, reducing the risk of thermal runaway, and improving reliability. The carbon-based material and the lithium-containing phosphate have high cycle stability. The use of lithium-containing phosphate as the positive electrode active material and the use of carbon-based material as the negative electrode active material can improve the cycle attenuation of the battery cell caused by the temperature rise process during fast charging, and improve the cycle performance of the battery cell 10. In the embodiment of the present application, the carbon-based material and the lithium-containing phosphate are used as the negative electrode active material and the positive electrode active material respectively, and combined with the heat exchange between the first side wall 12d and the heat exchange element 30, the fast charging capability of the battery cell can be improved, the influence of heat generation during fast charging on the cycle performance of the battery cell can be reduced, charging time can be saved, and the user experience can be improved.

[0161] In some embodiments, at room temperature, the charging time of the battery cell 10 from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes.

[0162] As an example, the room temperature may be an ambient temperature of 30°C.

[0163] SOC refers to the state of charge of the battery cell 10 .

[0164] Exemplarily, 100% SOC and 0% SOC are defined as follows: charging the battery cell at a constant current charge rate of 0.33C to the upper limit voltage of the battery charge, and then charging at a constant voltage to 0.05C, corresponding to the state of 100% SOC of the battery cell; discharging the battery cell at a constant current discharge rate of 0.33C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell. Exemplarily, the upper limit voltage of the battery charge can be 3.8V; the cut-off voltage of the battery discharge can be 2.0V.

[0165] Illustratively, the charging time of the battery cell 10 from 10% SOC to 80% SOC is 10.5 min, 10 min, 9.5 min, 9 min, 8.5 min, 8 min, 7.5 min, 7 min, 6.5 min, 6 min, 5.5 min, 5 min, or a range consisting of any two of the above values.

[0166] 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 cell 10, the heat exchange member 30 can exchange heat with the first side wall 12d to reduce the temperature rise of the battery cell 10 during the fast charging process; the carbon-based material and the lithium-containing phosphate have relatively high cycle stability, which can improve the cycle attenuation of the battery cell caused by the temperature rise during the fast charging process.

[0167] 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 in the following manner: Charge from 10% SOC to 15% SOC at a constant current of 5.0C; Charge from 15% SOC to 20% SOC at a constant current of 5.0C; Charge from 20% SOC to 25% SOC at a constant current of 5.0C; Charge from 25% SOC to 30% SOC at a constant current of 5.0C; Charge from 30% SOC to 35% SOC at a constant current of 5.0C; Charge from 35% SOC to 40% SOC at a constant current of 5.0C; Charge from 40% SOC to 45% SOC at a constant current of 4.6C; Charge from 45% SOC to 50% SOC at a constant current of 4.3C; Charge from 50% SOC to 55% SOC at a constant current of 4.0C; 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.

[0168] As an example, the above charging strategy is carried out in an environment of 30°C.

[0169] In some embodiments, the charging steps of the battery cell 10 from 0% SOC to 10% SOC can be carried out in the following manner: Charge from 0% SOC to 10% SOC at a constant current of 5.0C.

[0170] In some embodiments, the charging steps of the battery cell 10 from 80% SOC to 98% SOC can be carried out in the following manner: 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.

[0171] 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.

[0172] 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 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.

[0173] 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%.

[0174] As an example, the discharging strategy is to discharge at a constant current of 0.33C to 2.0V.

[0175] As an example, the charging strategy can be: Charge from 0% SOC to 5% SOC at a constant current of 5.0C; Charge from 5% SOC to 10% SOC at a constant current of 5.0C; Charge from 10% SOC to 15% SOC at a constant current of 5.0C; Charge from 15% SOC to 20% SOC at a constant current of 5.0C; Charge from 20% SOC to 25% SOC at a constant current of 5.0C; Charge from 25% SOC to 30% SOC at a constant current of 5.0C; Charge from 30% SOC to 35% SOC at a constant current of 5.0C; Charge from 35% SOC to 40% SOC at a constant current of 5.0C; Charge from 40% SOC to 45% SOC at a constant current of 4.6C; Charge from 45% SOC to 50% SOC at a constant current of 4.3C; Charge from 50% SOC to 55% SOC at a constant current of 4.0C; 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; 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; Charge from 98% SOC to 100% SOC at a constant current of 0.1C.

[0176] The battery cell 10 of the embodiment of the present application can charge from 10% SOC to 80% SOC within 10.5 minutes without lithium plating or with slight lithium plating, and has good fast charging ability. Exemplarily, when the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 0.05%, it can be considered that there is no lithium plating. When the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 2% and greater than or equal to 0.05%, it can be considered as slight lithium plating.

[0177] In some embodiments, the battery cell 10 is a square shell battery cell.

[0178] In some embodiments, the housing 12 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.

[0179] In some embodiments, both the first side wall 12d and the second side wall 12e are flat walls and are perpendicularly arranged.

[0180] In some embodiments, one first side wall 12d of the battery cell 10 is connected to the heat exchange member 30.

[0181] The lithium-containing phosphate with an olivine structure has excellent cycling stability. By using the lithium-containing phosphate with an olivine structure, the heat generation of the battery cell 10 during rapid charging can be reduced, and the risk of thermal runaway of the battery cell 10 can be lowered. By using the lithium-containing phosphate with an olivine structure, the heat exchange requirement can be reduced. In the embodiment of the present application, only one side first side wall 12d of the battery cell 10 is connected to the heat exchange member 30, which can reduce the number of heat exchange members 30, save space, and improve the energy density of the battery 2.

[0182] Of course, in an alternative embodiment, if the capacity of the battery 2 meets the requirements, the two first side walls 12d of the battery cell 10 can also be respectively connected to two heat exchange members 30 to improve the temperature control effect.

[0183] In some embodiments, the battery 2 includes a plurality of battery cell groups 100 and a plurality of heat exchange members 30. The plurality of battery cell groups 100 are arranged along the thickness direction X. Each battery cell group 100 includes at least two battery cells 10 arranged along a direction perpendicular to the thickness direction X. One heat exchange member 30 is provided between every two battery cell groups 100.

[0184] As an example, the battery cells 10 of the battery cell group 100 are arranged along the first direction Y.

[0185] As an example, the plurality of battery cells 10 of the battery 2 are arranged in an array within the box body 20.

[0186] As an example, the number of battery cells 10 in adjacent battery cell groups 100 may be the same or different.

[0187] The number of battery cell groups 100 can be even or odd.

[0188] In some examples, the number of battery cell groups 100 is 2n, where n is a positive integer. Along the thickness direction X, one 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 can be n.

[0189] In other examples, the number of battery cell groups 100 can be 2n + 1, where n is a positive integer. Along the thickness direction X, one 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 can be n + 1. One heat exchange member 30 can be correspondingly provided for the (2n + 1)th battery cell group 100. This heat exchange member 30 can be provided on the side of the (2n + 1)th battery cell group 100 away from the 2nth battery cell group 100, or can be provided between the (2n + 1)th battery cell group 100 and the 2nth battery cell group 100.

[0190] In the embodiments of the present application, a heat exchange member 30 can exchange heat with the battery cells 10 of two battery cell groups 100 simultaneously, which can reduce the number of heat exchange members 30 and improve the space utilization rate and energy density of the battery 2.

[0191] 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.

[0192] 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.

[0193] In some embodiments, the heat exchange member 30 is bonded to the first side wall 12d through a first adhesive layer 40. The first adhesive layer 40 can stably connect the heat exchange member 30 to the first side wall 12d to improve the stability of heat exchange between the heat exchange member 30 and the battery cell 10.

[0194] In some embodiments, the first adhesive layer 40 is a thermally conductive adhesive layer.

[0195] In some embodiments, the heat exchange member 30 includes a heat conducting plate 31, and a flow channel 311 is provided inside the heat conducting plate 31 for arranging a heat exchange medium.

[0196] As an example, the heat exchange medium can be a liquid or a gas, such as water.

[0197] The flow channel 311 can guide the flow of the heat exchange medium, so that the heat exchange medium exchanges heat with the battery cell 10 when flowing through the heat conducting plate 31.

[0198] In some embodiments, the heat conducting plate 31 is a metal plate or a non-metal plate.

[0199] In some embodiments, the heat exchange member 30 further includes an insulating layer 32, and at least a part of the insulating layer 32 is arranged between the heat conducting plate 31 and the first side wall 12d.

[0200] 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.

[0201] In some embodiments, the insulating layer 32 is arranged on the outer surface of the heat conducting plate 31.

[0202] In some embodiments, the insulating layer 32 is bonded to the first adhesive layer 40.

[0203] In some embodiments, the heat conducting plate 31 is made of an insulating non-metal material, and correspondingly, the insulating layer can be omitted.

[0204] 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.

[0205] In some embodiments, at least a part of the heat exchanger 30 is configured to be deformable in the thickness direction X. The battery cell 10 expands during cycling, and the heat exchanger 30 can be compressed when the battery cell 10 expands, thereby providing space for the expansion of the battery cell 10, reducing the pressure on the electrode assembly 11, and improving the cycling performance of the battery cell 10.

[0206] In some embodiments, the battery 2 further includes a connecting pipe group 50 for connecting a plurality of heat exchangers 30. The connecting pipe group 50 can communicate with the flow channels 311 of the plurality of heat exchangers 30, thereby enabling the heat exchange medium to flow in the flow channels 311.

[0207] 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 exchangers 30, and the outlet pipe communicates with the flow channels 311 of the plurality of heat exchangers 30.

[0208] 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.

[0209] In some embodiments, the outer shell 12 further includes a first end wall 12a and a second end wall 12b which are oppositely arranged, and a first side wall 12d connects the first end wall 12a and the second end wall 12b. The first end wall 12a is located below the electrode assembly 11, and the second end wall 12b is located above the electrode assembly 11 and is connected to the box body 20.

[0210] As an example, when the battery cell 10 is installed in an electrical device, the second end wall 12b can be located above the electrode assembly 11 in the vertical direction Z, and the first end wall 12a can be located below the electrode assembly 11 in the vertical direction Z. During the production, transportation, etc. of the battery cell 10, it is not required that the second end wall 12b is on the top and the first end wall 12a is on the bottom.

[0211] Fixing the second end wall 12b to the box body 20 can save the space above the battery cell 10 and improve the space utilization rate.

[0212] In some embodiments, a second side wall 12e connects the first end wall 12a and the second end wall 12b.

[0213] In some embodiments, the second end wall 12b is bonded to the box body 20.

[0214] As an example, the second end wall 12b is bonded to the box body 20 through the second adhesive layer 41. The second adhesive layer 41 can fix the battery cell 10 to the box body 20, thereby improving the stability of the battery cell 10. The second adhesive layer 41 is easy to form, which is beneficial to simplifying the assembly process.

[0215] In some embodiments, the box body 20 includes a first box wall 21, and the battery cell 10 is located below the first box wall 21. Exemplarily, the second end wall 12b is bonded to the first box wall 21 through the second adhesive layer 41.

[0216] Exemplarily, the first end wall 12a is located on the side of the electrode assembly 11 away from the first box wall 21.

[0217] The first box wall 21 can be a single-layer structure or a multi-layer structure. The first box wall 21 can be an integrally formed component or a component formed by connecting multiple independently formed components.

[0218] In some embodiments, the battery cell 10 further includes a pressure relief mechanism 15 provided on the first end wall 12a.

[0219] The first end wall 12a can be an end cap 122 or a wall of the housing 121.

[0220] In some examples, the pressure relief mechanism 15 and the first end wall 12a can be independently formed components, and the two can 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, and 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 can also be an integrally formed structure.

[0221] 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.

[0222] 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 easy to break, shatter, be torn or be opened.

[0223] In some examples, the present application may form a groove, a notch or other structures in a predetermined area of the pressure relief mechanism 15 to reduce the strength of a local part of the pressure relief mechanism 15, thereby forming a 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 some other examples, a material treatment may be performed on a predetermined area of the pressure relief mechanism 15 such that the strength of this area is weaker than that of other areas. In other words, this area is the weak part 151.

[0224] 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.

[0225] 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 disposed 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.

[0226] Optionally, the weak part 151 surrounds the pressure relief part 152 for one week.

[0227] Optionally, the fixing part 153 is welded to the first end wall 12a.

[0228] 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 enhance the reliability of the battery 2.

[0229] 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.

[0230] As an example, a groove, a notch or other structures may be formed on the first end wall 12a to form an annular weak part 151. The weak part 151 and the area surrounded by the weak part 151 constitute the pressure relief mechanism 15.

[0231] As an example, the first end wall 12a may be the bottom wall of the housing 121.

[0232] In some embodiments, the housing 121 includes a second end wall 12b, two first side walls 12d and two second side walls 12e. The first end wall 12a is an end cover 122.

[0233] In some embodiments, the battery cell 10 further includes a sampling member 16 disposed on the outer casing 12, and the sampling member 16 is used for collecting the temperature of the outer casing 12.

[0234] The sampling member 16 can be disposed inside the housing 12 or can be disposed inside the housing 12.

[0235] The sampling member 16 can collect the temperature of the housing 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.

[0236] In some embodiments, the sampling member 16 is disposed on the end cap 122.

[0237] In some embodiments, there are multiple sampling members 16, and the multiple sampling members 16 can be disposed at positions with relatively high temperatures during the cycling of the battery cell 10.

[0238] In some embodiments, the sampling member 16 includes a negative temperature coefficient thermistor.

[0239] In some embodiments, the housing 12 further includes a first end wall 12a, and the first end wall 12a connects two first side walls 12d. 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 body 11a and a first tab 11b extending from the electrode body 11a, and the first electrode terminal 13 is electrically connected to the first tab 11b.

[0240] By disposing the first electrode terminal 13 on the first end wall 12a, the risk of interference between the first electrode terminal 13 and the heat exchange member 30 can be reduced, and the heat exchange efficiency can be improved.

[0241] In some embodiments, the first end wall 12a is located on the lower side of the electrode assembly 11. By disposing the first electrode terminal 13 on the first end wall 12a, the space on the lower side of the battery cell 10 can be fully utilized, and the space utilization rate can be improved.

[0242] In some embodiments, the second electrode terminal 14 is also disposed on the first end wall 12a.

[0243] In some embodiments, at least a part of the first electrode terminal 13 is located outside the first end wall 12a.

[0244] One 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 outside the plane of the outer surface 1221 of the first end wall 12a.

[0245] In some examples, the first electrode terminal 13 can be entirely located outside the first end wall 12a; alternatively, in 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 housing 12.

[0246] The portion of the first electrode terminal 13 located outside the first end wall 12a can be used to connect to the current collecting component of the battery 2.

[0247] In some embodiments, the area of the projection of the portion 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 optionally 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 .

[0248] Exemplarily, the projection of the portion of the first electrode terminal 13 located outside the first end wall 12a on the first end wall 12a is: the projection of the portion 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.

[0249] The portion of the first electrode terminal 13 located outside the first end wall 12a has a large area, which can increase the current-carrying 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 large exposed area, which can increase the heat dissipation efficiency of the first electrode terminal 13.

[0250] 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.

[0251] Optionally, the width direction of the first end wall 12a is parallel to the thickness direction X of the battery cell 10.

[0252] As an example, W2 / W1 is 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.

[0253] Setting W2 / W1 to be greater than or equal to 0.4 can make the first electrode terminal 13 have a large exposed area, increase the connection area between the first electrode terminal 13 and the current collecting component, improve the current-carrying 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.

[0254] In some embodiments, W2 / W1 is 0.6 - 0.9.

[0255] 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.

[0256] 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.

[0257] Figure 9 It is a partial cross-sectional schematic diagram of the battery cell provided in some other embodiments of the present application.

[0258] In some embodiments, referring to Figure 9 , the first end wall 12a has an inner surface 1222 facing the electrode assembly 11. Along the direction close to the electrode assembly 11, the first electrode terminal 13 does not extend beyond the inner surface 1222.

[0259] The first electrode terminal 13 can not occupy the internal space of the housing 12, thereby improving the space utilization rate of the battery cell 10 and enhancing the energy density of the battery cell 10.

[0260] 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. In the axial direction of the electrode lead-out hole 1223, the first electrode terminal 13 covers the electrode lead-out hole 1223.

[0261] 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. The second fixing member 18 is connected to the first fixing member 17 and fixedly connected to the first end wall 12a.

[0262] In some embodiments, a part of the second fixing member 18 is embedded into the first fixing member 17.

[0263] In some embodiments, the second fixing member 18 is welded to the first end wall 12a.

[0264] In some embodiments, the first fixing member 17 is an insulating member. The first fixing member 17 is formed by an injection molding process.

[0265] Figure 10 It is a partial cross-sectional schematic diagram of the battery cell provided in some other embodiments of the present application.

[0266] Referring to Figure 10, 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 body 11a and is connected to the connecting portion 131.

[0267] By providing the through hole 1311, the first tab 11b can be led out to the outside of the connecting portion 131, thereby reducing the distance between the connecting portion 131 and the electrode body 11a, improving the utilization rate of the internal space of the battery cell 10, and increasing the energy density of the battery cell 10.

[0268] 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, thus eliminating the conventional adapter plate and increasing the energy density.

[0269] In some embodiments, the first electrode terminal 13 includes a terminal body 132 and a cover plate 133. The terminal body 132 is fixed to the first end wall 12a. The terminal 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 body 11a and is connected to the terminal body 132. The cover plate 133 can be used to separate the through hole 1311 from the external space of the battery cell 10.

[0270] In some embodiments, a recess 134 is provided on the side of the terminal body 132 away from the electrode body 11a. The bottom wall of the recess 134 is the connecting portion 131. The cover plate 133 is disposed on the side of the connecting portion 131 away from the electrode body 11a and is used to cover the recess 134.

[0271] The recess 134 can accommodate a part of the first tab 11b, thereby improving the space utilization rate. 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.

[0272] In some embodiments, at least a part of the cover plate 133 is received in the recess 134. By using the recess 134 to accommodate the cover plate 133, the space utilization rate can be improved.

[0273] In some embodiments, the cover plate 133 is welded to the terminal body 132.

[0274] 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.

[0275] In some embodiments, the through hole 1311 is a strip-shaped hole, and the strip-shaped hole extends along the length direction of the first end wall 12a.

[0276] Figure 11A cross-sectional schematic diagram of the battery provided by some embodiments of the present application; Figure 12 is Figure 11 An enlarged schematic diagram at the circular frame.

[0277] Referring to Figure 11 and Figure 12 In some embodiments, the box body 20 includes a second box wall 22, and the second box wall 22 is disposed on the lower side of the battery cell 10.

[0278] The second box wall 22 can be a single-layer structure or a multi-layer structure.

[0279] 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.

[0280] In some embodiments, the first box wall 21 and the second box wall 22 are arranged up and down along the vertical direction Z.

[0281] In some embodiments, 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.

[0282] 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.

[0283] In some embodiments, the second box wall 22 is spaced apart from the battery cell 10.

[0284] When the battery cell 10 is in thermal runaway, the space between the second box wall 22 and the battery cell 10 can serve as an exhaust channel, so as to timely discharge the substances released by the battery cell 10 to the outside of the box body 20 and reduce 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, reduce the impact force conducted to the battery cell 10, reduce the risk of the battery cell 10 failing, and improve the reliability of the battery 2.

[0285] 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 and the space utilization rate in the vertical direction Z can be improved.

[0286] In some embodiments, the battery 2 further includes a support member 60, and the support member 60 is disposed on the lower side of the outer shell 12 and is used to support the outer shell 12.

[0287] As an example, the support member 60 is disposed on the lower side of the first end wall 12a and is used to support the first end wall 12a.

[0288] There may be one or more support members 60.

[0289] The support member 60 may be in contact with the second box wall 22 or may be spaced apart from the second box wall 22.

[0290] 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.

[0291] In some embodiments, the box body 20 includes a second box wall 22 disposed on the lower side of the battery cell 10. The support member 60 is bonded to the outer shell 12 and the second box wall 22.

[0292] The support member 60 connects the battery cell 10 to the second box wall 22, thereby enhancing the overall structural strength of the battery 2.

[0293] 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.

[0294] In some embodiments, the elastic modulus of the support member 60 is less than the elastic modulus of the second box wall 22.

[0295] Since the elastic modulus of the support member 60 is 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.

[0296] 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 improved.

[0297] 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 spaced apart along the first direction Y.

[0298] 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 disposed between the two support members 60.

[0299] In some embodiments, one support member 60 can support two adjacent battery cells 10 along the first direction Y at the same time.

[0300] In some embodiments, there is a gap between the support member 60 and the heat exchange member 30 in the vertical direction Z.

[0301] Figure 13 A cross-sectional schematic diagram of a battery provided for other embodiments of the present application; Figure 14 For Figure 13 An enlarged schematic diagram at the square box; Figure 15 A cross-sectional schematic diagram of a support member of a battery provided for some embodiments of the present application.

[0302] Referring to Figure 6 、 Figures 13 to 15 In some embodiments, the box body 20 includes a plurality of limiting beams 24, and the plurality of limiting beams 24 are arranged at intervals along the thickness direction X of the battery cell 10, and a plurality of battery cells 10 are arranged between adjacent limiting beams 24.

[0303] The number of limiting beams 24 can be two or more. As an example, a battery cell 10 is arranged between any two adjacent limiting beams 24.

[0304] As an example, the limiting beam 24 is connected to the first box wall 21.

[0305] The limiting beam 24 can be used to limit the expansion deformation of the battery cell 10 in the thickness direction X. The limiting beam 24 can directly abut against the battery cell 10 in the thickness direction X; alternatively, other components can also be arranged between the limiting beam 24 and the battery cell 10, that is, the limiting beam 24 limits the expansion of the battery cell 10 through this component.

[0306] The limiting beam 24 has high anti-deformation ability, and it can provide effective constraint to the battery cell 10 in the thickness direction X, reduce the maximum expansion amount of the battery cell 10 in the thickness direction X, and improve the cycle performance of the battery cell 10.

[0307] In some embodiments, an insulating pad 43 is arranged between the battery cell 10 and the limiting beam 24.

[0308] In some embodiments, the support member 60 connects adjacent limiting beams 24.

[0309] The number of support members 60 can be one or more.

[0310] The support member 60 can be connected to the limiting beam 24 by welding, snap connection, fastener connection or other connection methods.

[0311] The support member 60 is in a strip structure, a linear structure, a beam structure or other structures. Exemplarily, the support member 60 extends along the thickness direction X of the battery cell 10.

[0312] During the cycling of the battery cell 10, the battery cell 10 expands and applies a force to 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.

[0313] In some embodiments, the support member 60 can apply a pre-tightening force to the adjacent limiting beam 24.

[0314] In some embodiments, the support member 60 is a strip structure. The strip structure has a low cost and occupies a small space; by using the support member 60 with a strip structure, the space utilization rate inside the battery 2 can be improved, and the energy density of the battery 2 can be increased. 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.

[0315] Exemplarily, the metal strip 61 includes a steel strip.

[0316] The metal strip 61 has a 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.

[0317] 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.

[0318] In some embodiments, the metal strip 61 has a cavity 63.

[0319] In some embodiments, the support member 60 is bonded to the first end wall 12a. The support member 60 is bonded to the battery cell 10, which can increase the connection strength between the battery cell 10 and the box body 20, reduce the sway of the battery cell 10 relative to the box body 20 when the battery 2 is impacted, and improve the reliability and stability of the battery 2.

[0320] 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 bonded to the second box wall 22.

[0321] In some embodiments, the support member 60 is detachably connected to the limiting beam 24.

[0322] 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.

[0323] In some embodiments, the expansion pressure of the battery cell 10 in its own thickness direction X is 0.5 MPa - 2.4 MPa.

[0324] 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.

[0325] As an example, the expansion pressure of the battery cell 10 can be measured in the following manner: At 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). At an ambient temperature of 45°C, charge the battery cell at a constant current charge rate of 0.8C until 3.8V, and detect and record the pressure exerted by the battery cell on the clamping plate. Perform cyclic charge and discharge on the battery cell according to the above charging strategy and charging strategy until the battery cell is cycled to 70% SOH (i.e., the capacity retention rate of the battery cell = the discharge capacity of the battery cell / the nominal capacity of the battery cell = 70%), and record the maximum pressure exerted by the battery cell on the clamping plate. Calculate the expansion pressure Q of the battery cell in the thickness direction as: maximum pressure / large surface area.

[0326] The expansion pressure of the battery cell 10 is related to the compactness of the electrode assembly 11. The battery cell 10 has an expansion pressure greater than or equal to 0.5 MPa in the thickness direction X, thereby improving the compactness of the electrode assembly 11 and increasing the energy density of the battery cell 10. The expansion pressure of the battery cell 10 in the thickness direction X is less than or equal to 2.4 MPa 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.

[0327] In the embodiment of the present application, the expansion pressure of the battery cell 10 in the thickness direction X is limited to 0.5 MPa - 2.4 MPa to reduce the expansion 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.

[0328] Limiting the expansion pressure of the battery cell 10 to 1.5 MPa - 2.0 MPa can reduce the requirements for the strength of the limiting beam 24 and reduce costs.

[0329] In some embodiments, the box body 20 includes a plurality of limiting beams 24, and the plurality of limiting beams 24 are arranged at intervals along the thickness direction X of the battery cell 10. A plurality of battery cells 10 are provided between adjacent limiting beams 24. In the thickness direction X, the distance between two adjacent limiting beams 24 is D1, and the sum of the sizes of all the electrode assemblies 11 stacked along the thickness direction X between two adjacent limiting beams 24 is D2. 85% ≤ D2 / D1 ≤ 92%.

[0330] Exemplarily, between adjacent limiting beams 24, the number of battery cell groups 100 is M 1 . Between adjacent limiting beams 24, the number of a row of battery cells 10 arranged in the thickness direction X is M 1 . Each battery cell 10 includes M 2 electrode assemblies 11.

[0331] When the battery 2 is at 0% SOC, the battery cell 10 is removed and the distance between the two limiting beams 24 in the thickness direction X is measured as D1; the removed battery cell 10 is disassembled and the electrode assemblies 11 are taken out, and the thicknesses of the M 1 ×M 2 electrode assemblies 11 arranged in the thickness direction X are measured and summed to obtain D2.

[0332] Exemplarily, when the battery cell 10 is at % SOC, the size of the electrode assembly 11 along the thickness direction X is T; D2 = M 1 ×M 2 ×T.

[0333] 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.

[0334] Figure 16 Schematic diagram of a battery cell and a first busbar component provided by some embodiments of the present application; Figure 17 For Figure 16 schematic diagram of the first busbar component.

[0335] 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.

[0336] Multiple busbar components can connect multiple battery cells 10 in series, parallel, or in a series-parallel combination.

[0337] The multiple busbar components can have the same structure or different structures.

[0338] In some embodiments, the multiple 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 is electrically connected to at least two battery cells 10 arranged along the thickness direction X.

[0339] All of the multiple busbar components can be first busbar components 70, or some of them can be first busbar components 70.

[0340] 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.

[0341] 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. This can enable the first busbar component 70 to have a relatively large current-carrying area, thereby reducing the heat generation of the first busbar component 70, enhancing the fast charging ability of the battery 2, and reducing the risk of thermal runaway.

[0342] On the premise that the current-carrying area meets the requirements, setting the first busbar component 70 to a double-layer structure can reduce the requirement for the thickness of the first busbar layer 71. During the cycling process, the battery cell 10 will expand, thereby stretching the first busbar layer 71. The first busbar layer 71 has a relatively small thickness and is easy to deform to adapt to the deformation of the battery cell 10, reducing the risk of the connection between the battery cell 10 and the first busbar layer 71 being torn, and enhancing the reliability of the battery 2.

[0343] In some embodiments, the thickness of the first busbar layer 71 is 1 mm - 2.5 mm. Optionally, the thickness of the first busbar layer 71 is 1.2 mm - 1.8 mm. As an example, the thickness of the first busbar 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 busbar layer 71 is selected according to the expansion pressure of the battery cell 10, which can balance the current-carrying ability and the deformability of the first busbar layer 71 to a certain extent, thereby enhancing the fast charging ability and reliability of the battery 2.

[0344] 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.

[0345] 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 over-current capacity of the battery for the first current collecting component. Exemplarily, when the thickness of the first current collecting layer 71 is small, the second current collecting layer 72 can have a thickness greater than that of the first current collecting layer 71 to enhance the over-current capacity of the first current collecting component.

[0346] 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.

[0347] In some embodiments, the first current collecting layer 71 is welded to the first electrode terminal 13 and / or the second electrode terminal 14.

[0348] 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.

[0349] The bending portion 73 can be one or multiple.

[0350] 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 enhancing the over-current capacity of the first current collecting component 70.

[0351] 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.

[0352] 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.

[0353] During the cycling of the battery cell 10, the battery cell 10 expands and applies a tensile force to the first current collecting layer 71; the first buffer portion 713 can release stress through deformation, thereby reducing the stress on the connection between the first current collecting portion 711 and the battery cell 10 and the stress on 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.

[0354] In some embodiments, the bent portion 73 is not directly connected to the first buffer portion 713. The bent portion 73 is not directly connected to the first buffer portion 713, thereby reducing the influence of the bent portion 73 on the deformation of the first buffer portion 713 and reducing the difficulty of deforming the first buffer portion 713.

[0355] In some embodiments, the first buffer portion 713 includes an arched structure.

[0356] 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.

[0357] 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 is connected by at least one bent portion 73. The second stacked portion 722 is stacked with the second current collecting portion 712 and is connected by at least one bent portion 73. The second buffer portion 723 connects the first stacked portion 721 and the second stacked portion 722.

[0358] 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.

[0359] 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.

[0360] 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.

[0361] 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 to each other, thereby reducing the risk of interference between the first buffer portion 713 and the second buffer portion 723 and other parts during deformation.

[0362] In some embodiments, the second busbar layer 72 is located on the side of the first busbar layer 71 away from the battery cell 10.

[0363] In some embodiments, the second busbar layer 72 is located below the first busbar layer 71.

[0364] In some embodiments, the plurality of busbar components further include a second busbar component (not shown) having a single-layer structure. In the battery 2, the expansion amounts of the battery cells 10 at different positions may be different. For the battery cells 10 with a smaller expansion amount, a second busbar component with a single-layer structure can be used; compared with the first busbar component 70, the second busbar component has a simple structure, is easy to manufacture, and can save costs. The thickness of the second busbar component is greater than the thicknesses of the first busbar layer 71 and the second busbar layer 72, and its current-carrying capacity can meet the requirements.

[0365] Figure 18 This is an explosion schematic diagram of the battery provided in other embodiments of the present application.

[0366] In some embodiments, the box body 20 includes a first box wall 21 located above the battery cell 10, and the battery cell 10 is fixed to the first box wall 21.

[0367] 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 at least part of the floor can save vehicle components, improve the integration of the vehicle, and simplify the vehicle assembly process.

[0368] In some embodiments, the battery 2 further includes a mounting beam 80, and the mounting beam 80 is disposed on the side of the first box wall 21 facing away from the battery cell 10.

[0369] The mounting beam 80 is connected to the first box wall 21, which can enhance 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 components, improving integration, and simplifying the assembly process.

[0370] In some embodiments, the mounting beam 80 is used to mount the vehicle seat. The embodiments of the present application can improve the space utilization rate of the whole vehicle. The combination of the mounting beam 80 and the first box wall 21 can save more space in the vertical direction Z, so that the size of the battery cell 10 in the vertical direction Z can be further increased, and the energy density of the battery 2 can be improved.

[0371] Figure 19A cross-sectional schematic view of the negative electrode sheet of the battery cell provided in other embodiments of the present application.

[0372] Please refer to Figures 6 to 8 、 Figure 19 , in some embodiments, in some embodiments, a part of the negative electrode current collector 1121 is not covered by the negative electrode film layer 1122; the part of the negative electrode current collector 1121 not covered by the negative electrode film layer 1122 can be used to form the negative electrode tab.

[0373] 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.

[0374] 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 .

[0375] Exemplarily, when the battery cell 10 is at 100% SOC, 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.

[0376] Exemplarily, the compaction density of the negative electrode film layer of the battery cell 10 at 100% state of charge has the meaning well known in the art, that is, the negative electrode sheet is disassembled from the battery cell at 100% SOC, and the compaction density of the negative electrode film layer is measured; for example, take a single-sided coated negative electrode sheet (if it is a double-sided coated negative electrode sheet, the negative electrode film layer on one side can be wiped off first), punch it into small round pieces with an area of S1, weigh it, record it as M1, and measure its thickness H1. Then wipe off the negative electrode film layer of the above weighed negative electrode sheet, weigh the weight of the negative electrode current collector, record it as M0, and measure its thickness H0. The single-sided coating weight of the negative electrode film layer = (the weight M1 of the negative electrode sheet - the weight M0 of the negative electrode current collector) / S1, the thickness of the negative electrode film layer = the thickness H1 of the negative electrode sheet - the thickness H0 of the negative electrode current collector, and the compaction density of the negative electrode film layer = the single-sided coating weight of the negative electrode film layer / the thickness of the negative electrode film layer.

[0377] The tap density of the negative electrode film layer 1122 is related to the swelling of the battery cell 10 at 100% state of charge. Limiting the tap density of the negative electrode film layer 1122 to 1.15 g / cm 3 to 1.36 g / cm 3 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, and reduce the risk of connection failure between the battery cell 10 and the busbar component.

[0378] When the tap 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, the resistance of the negative electrode sheet 112 can be reduced, thereby reducing heat generation, which is beneficial to improving the fast charging ability of the battery 2.

[0379] When the tap 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 tap density of the negative electrode film layer 1122 is small, the porosity of the negative electrode sheet 112 can be increased, the swelling of the negative electrode sheet can be slowed down, and the swelling pressure of the battery cell 10 can be reduced.

[0380] In some embodiments, the tap 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.

[0381] 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 mm2 , 115 mg / 1540.25 mm 2 , 116 mg / 1540.25 mm 2 , 118 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 122 mg / 1540.25 mm 2 , 125 mg / 1540.25 mm 2 , 128 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 132 mg / 1540.25 mm 2 , 135 mg / 1540.25 mm 2 , 137 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 142 mg / 1540.25 mm 2 , 145 mg / 1540.25 mm 2 , 148 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 152 mg / 1540.25 mm 2 , 155 mg / 1540.25 mm 2 , 160 mg / 1540.25 mm 2 , 165 mg / 1540.25 mm 2 , 167 mg / 1540.25 mm 2 , 170 mg / 1540.25 mm 2 or a range composed of any two of the above values.

[0382] The single-sided coating weight of the negative electrode film layer 1122 is related to the swelling of the negative electrode film layer. Limiting the single-sided coating weight of the negative electrode film layer 1122 to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 can, to a certain extent, balance the energy density and swelling pressure of the battery cell 10, reduce the deformation of the battery cell 10, lower the risk of connection failure between the battery cell 10 and the current collecting component, and improve the reliability.

[0383] In addition, limiting the single-sided coating weight of the negative electrode film layer 1122 to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 can also limit the heat generation amount per unit area of the negative electrode sheet 112 and reduce the temperature rise of the battery cell 10, especially the temperature rise during fast charging.

[0384] In some embodiments, the single-sided coating weight of the negative electrode film layer 1122 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 , so as to further balance the energy density and expansion pressure of the battery cell 10.

[0385] 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%.

[0386] 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.

[0387] 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 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 cycling 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.

[0388] 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.

[0389] 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.

[0390] 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.

[0391] In some embodiments, the negative electrode active material further includes a silicon-based material. The introduction of the silicon-based material can increase the capacity of the negative electrode active material and improve the energy density of the battery cell 10.

[0392] In some embodiments, the mass content of silicon element in the silicon-based material in the negative electrode active material is 0.3% to 10%, and optionally 1% to 6%. Exemplarily, the mass content of silicon element in the negative electrode active material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10% or a range composed of any two of the above values.

[0393] Introducing the silicon-based material into the negative electrode sheet 112 can not only improve the capacity, but also increase the expansion of the negative electrode sheet 112. Therefore, limiting the mass content of silicon element in the negative electrode active material to 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.

[0394] In this application, the qualitative and quantitative determination of each substance or each element can be detected 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.

[0395] For example, the silicon-based material can be combined with the general rules of X-ray diffraction analysis method in JIS / K0131-1996 to perform X-ray powder diffraction test and qualitative analysis on the negative electrode sheet or the negative electrode active material.

[0396] 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.

[0397] In some embodiments, the silicon-based material includes at least one of silicon oxide compound and silicon-carbon composite.

[0398] In some embodiments, in addition to the carbon-based material and the optional silicon-based material, the negative electrode active material may further include at least one of a tin-based material and lithium titanate. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.

[0399] 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.

[0400] When the negative electrode film layer 1122 is a single-layer film layer, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. When a single-layer film layer is used, the volume average particle diameter Dv50 of the negative electrode active material is 8.2 μm to 13.5 μm. Exemplarily, the volume average particle diameter Dv50 of the negative electrode active material is 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm or a range composed of any two of the above values.

[0401] 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.

[0402] In some embodiments, the negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222. The second negative electrode film layer 11222 is disposed between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material disposed in the first negative electrode film layer 11221 and a second negative electrode active material disposed in the second negative electrode film layer 11222. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials.

[0403] 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.

[0404] 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.

[0405] Artificial graphite can have a relatively small volume average particle size Dv50, which can, on the one hand, 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.

[0406] 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.

[0407] 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.

[0408] 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 transmission can be reduced, and the fast-charging ability of the battery cell 10 can be improved.

[0409] 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.

[0410] In some embodiments, the first negative electrode active material is granular, and the second negative electrode active material is granular.

[0411] 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.

[0412] 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 transmission 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 relatively large 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.

[0413] In some embodiments, the volume-average particle size Dv50 of the first negative electrode active material is 7.8 μm - 14.3 μm, and may 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.

[0414] 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.

[0415] The volume-average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume-average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. It can be detected by using the equipment and methods well-known in the art. For example, taking the negative electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer.

[0416] In some embodiments, the volume-average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, and may be optionally 9.5 μm - 14.6 μm.

[0417] 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.

[0418] 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 conducive to improving the fast charging ability of the battery cell 10, and reducing the swelling of the negative electrode film layer 1122 during charging.

[0419] 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.

[0420] 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.

[0421] 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.

[0422] The specific surface area of the material has the meaning well-known in the art and can be detected by equipment and methods well-known in the art. For example, detection is carried out 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.

[0423] 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 swelling of the negative electrode sheet, and reduce the swelling pressure.

[0424] In some embodiments, the chemical formula of the lithium-containing phosphate with olivine structure is LiFe 1-x-y Mn x M y PO 4 , 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, Hf, Ta, Mo, W, Ru, Ag, Sn, and Pb.

[0425] 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.

[0426] 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 lithium-containing phosphate with olivine structure or its modified material system. 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.

[0427] Optionally, the mass percentage of the lithium-containing phosphate with olivine structure or its modified material in the positive electrode active material is 100%.

[0428] 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 .

[0429] Exemplarily, at 100% state of charge (SOC) of the battery cell 10, 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 a range composed of any two of the above values.

[0430] 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.

[0431] 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.

[0432] 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, it can be 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2 .

[0433] 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 it is a range composed of any two of the above values.

[0434] 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 using the equipment and methods well known in the art. Its detection method is the same as the single-sided coating weight test method of the negative electrode film layer 1122 described above.

[0435] 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 take into account the improvement of the energy density and charging rate performance of the battery cell 10.

[0436] 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.

[0437] 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 like the porosity test method of the negative electrode sheet 112.

[0438] The porosity of the positive electrode sheet 111 being greater than or equal to 25% can provide space for the impurities generated by side reactions of the positive electrode sheet 111, reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell 10, and improve the cycling performance of the battery cell 10. The porosity of the positive electrode sheet 111 being less than or equal to 32% can take into account the energy density of the battery cell 10 to a certain extent.

[0439] 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 a range composed of any two of the above values.

[0440] In the embodiments of the present application, the thickness of the positive electrode sheet 111 has the meaning well-known in the art, and can be detected by using the equipment and methods well-known in the art. For example, a micrometer can be used to measure the thickness of the positive electrode sheet 111.

[0441] Using a positive electrode sheet 111 with a smaller thickness can shorten the ion migration path, increase the ion migration rate, reduce the heat generation of the battery cell 10, and improve the fast charging performance of the battery cell 10.

[0442] In some embodiments, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05 to 0.3. Exemplarily, in the embodiments of the present application, the thickness of the positive electrode film layer 1112 is the thickness of the positive electrode film layer 1112 on one side of the positive electrode current collector 1111.

[0443] 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 a range composed of any two of the above values.

[0444] Limiting the thickness ratio of the positive current collector 1111 to the thickness of the positive film layer 1112 to be greater than or equal to 0.05 can improve the current capacity of the positive current collector 1111, reduce the temperature rise of the positive electrode sheet 111, and improve the fast charging performance of the battery cell 10; limiting the thickness ratio of the positive current collector 1111 to the thickness of the positive film layer 1112 to be less than or equal to 0.3 can reduce the capacity loss of the positive electrode sheet 111. In the embodiment of the present application, the thickness ratio of the positive current collector 1111 to the thickness of the positive film layer 1112 is limited to 0.05 to 0.3, which can take into account the fast charging capability and energy density of the battery cell 10 to a certain extent.

[0445] The thickness of the positive electrode film layer and the thickness of the positive electrode current collector are well known in the art and can be detected by equipment and methods well known in the art. For example, the thickness of the positive electrode sheet is measured using a micrometer, and the film layer on the surface of the positive electrode current collector is removed, and the thickness of the positive electrode current collector is measured using a micrometer. When the positive electrode film layer is coated on one side, the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector; when the positive electrode film layer is coated on both sides, the thickness of the positive electrode film layer is: (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector) / 2.

[0446] In some embodiments, the thickness of the positive current collector 1111 is 10 μm to 15 μm, and can be 12 μm to 15 μm. Exemplarily, the thickness of the positive current collector 1111 is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, or a range consisting of any two of the above values. When the thickness of the positive current collector 1111 is within the above range, the positive current collector 1111 has excellent current flow capacity and can enable the battery cell 10 to have a higher energy density.

[0447] In some embodiments, a portion of the positive electrode current collector 1111 is not covered by the positive electrode film layer 1112 ; the portion of the positive electrode current collector 1111 not covered by the positive electrode film layer 1112 can be used to form a positive electrode tab.

[0448] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm, 0.4µm≤Dv10≤0.7µm.

[0449] Illustratively, the Dv50 of the positive electrode active material can be 1µm, 1.1µm, 1.15µm, 1.2µm, 1.25µm, 1.3µm, 1.35µm, 1.4µm, 1.45µm, 1.5µm, 1.55µm, 1.6µm, 1.65µm, 1.7µm, 1.75µm, 1.8µm, 1.85µm, 1.9µm, 1.95µm, 2µm, or a range consisting of any two of the above values.

[0450] Exemplarily, the Dv10 of the positive electrode active material can be 0.4 µm, 0.45 µm, 0.5 µm, 0.55 µm, 0.6 µm, 0.65 µm, 0.7 µm, or a range composed of any two of the above values.

[0451] The particle size of the positive electrode active material is relatively small, the lithium intercalation and deintercalation 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.

[0452] 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.

[0453] 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 intercalated 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.

[0454] 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.

[0455] 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.

[0456] 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.

[0457] 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.

[0458] 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.

[0459] 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.

[0460] 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.

[0461] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents.

[0462] 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.

[0463] In some embodiments, the mass content of the chain carboxylate solvent in the organic solvent is 30% to 70%.

[0464] In some embodiments, the carboxylate includes R1-COO-R2, and R1 and R2 independently include an alkyl group with 1 to 5 carbon atoms or a halogenated alkyl group with 1 to 5 carbon atoms. The conductivity of the above chain carboxylate solvent is relatively high, which is beneficial to improving the fast charging ability of the battery cell 10.

[0465] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0466] Further optionally, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0467] The above-mentioned carbonate solvents and chain carboxylic ester solvents are used in combination, which improves the conductivity of the electrolyte and is beneficial to the migration of lithium ions.

[0468] 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.

[0469] 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%.

[0470] The organic solvent combination can improve the conductivity of the electrolyte and reduce the viscosity, thereby improving the fast charging performance of the battery.

[0471] 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.

[0472] Optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0473] 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 6 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 6The molar concentration is 0.8 mol / L.

[0474] Optionally, the molar concentration of lithium bis(fluorosulfonyl)imide and the molar concentration of lithium hexafluorophosphate LiPF 6 in is in a ratio of (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 in is 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10, 5:10 or a range composed of any two of the above values.

[0475] 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 aforementioned devices or systems using the battery 2.

[0476] Referring to Figures 2 to 5 , the 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.

[0477] 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.

[0478] 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.

[0479] One heat exchange member 30 is provided between every two battery cell groups 100.

[0480] 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 and a second end wall 12b. 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.

[0481] The housing 12 includes two first side walls 12d and two second side walls 12e.

[0482] The two first side walls 12d are oppositely arranged along the thickness direction X of the battery cell 10; each first side wall 12d connects the first end wall 12a and the second end wall 12b.

[0483] Two second side walls 12e are arranged opposite to each other along a first direction Y perpendicular to the thickness direction X; each second side wall 12e connects two first side walls 12d. Each second side wall 12e connects a first end wall 12a and a second end wall 12b.

[0484] One first side wall 12d of the battery cell 10 is connected to the heat exchange member 30 for heat exchange. The pressure relief mechanism 15 is arranged on the first end wall 12a.

[0485] The electrode assembly 11 includes a positive electrode plate 111, a negative electrode plate 112, and a separator 113 located between the positive electrode plate 111 and the negative electrode plate 112. The positive electrode plate 111 includes a positive electrode current collector 1111 and a positive electrode film layer 1112 provided on at least one side of the positive electrode current collector 1111. The positive electrode film layer 1112 includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure. The negative electrode plate 112 includes a negative electrode current collector 1121 and a negative electrode film layer 1122 provided on at least one side of the negative electrode current collector 1121. The negative electrode film layer 1122 includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0486] Under room temperature conditions, the charging time of the battery cell 10 from 10% SOC to 80% SOC can be 5 min to 10.5 min.

[0487] 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.

[0488] 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: Box; A battery cell is contained in the box, the battery cell comprises a shell and an electrode assembly contained in the shell, the shell comprises two first side walls arranged opposite to each other along the thickness direction of the battery cell; a heat exchange member, arranged on at least one side of the battery cell along the thickness direction and used for exchanging heat with the first side wall; the heat exchange member comprises a heat conducting plate, a flow channel is arranged inside the heat conducting plate, and the flow channel is used for arranging a heat exchange medium; The battery further comprises a support member, which is disposed on the lower side of the housing and is used to support the housing; The box body includes a plurality of limit beams, and the plurality of limit beams are arranged at intervals along the thickness direction of the battery cell, and a plurality of the battery cells are arranged between adjacent limit beams; wherein 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 on at least one side of the positive electrode collector, 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.

2. The battery according to claim 1, characterized in that Under room temperature conditions, the battery cell takes 5 minutes to 10.5 minutes to charge from 10% SOC to 80% SOC.

3. The battery according to any one of claims 1 to 2, characterized in that: One of the first side walls of the battery cell is connected to the heat exchange element.

4. The battery according to any one of claims 1 to 2, characterized in that: It comprises a plurality of battery cell groups and a plurality of heat exchangers, 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 a direction perpendicular to the thickness direction; A heat exchange element is provided between every two battery cell groups.

5. The battery according to any one of claims 1 to 2, characterized in that: The heat exchange element is bonded to the first side wall through a first adhesive layer.

6. The battery according to claim 5, characterized in that The heat exchange element further includes an insulating layer, at least a portion of which is disposed between the heat conducting plate and the first side wall.

7. The battery according to claim 6, characterized in that The thermal conductivity of the insulating layer is greater than or equal to 0.1 W / (m·K).

8. The battery according to any one of claims 1 to 2, characterized in that: The housing further comprises a first end wall and a second end wall which are arranged opposite to each other, and the first side wall connects the first end wall and the second end wall; The first end wall is located at the lower side of the electrode assembly, and the second end wall is located at the upper side of the electrode assembly and connected to the box body.

9. The battery according to claim 8, characterized in that The second end wall is bonded to the box body.

10. The battery according to claim 8, characterized in that The battery cell further includes a pressure relief mechanism disposed on the first end wall.

11. The battery according to any one of claims 1 to 2, characterized in that: The housing further comprises a first end wall, wherein the first end wall connects the two first side walls; 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.

12. The battery according to claim 11, characterized in that The area of ​​the orthographic projection 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 .

13. The battery according to claim 11, 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.

14. The battery according to claim 11, 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.

15. The battery according to claim 14, 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.

16. The battery according to claim 15, characterized in that At least a portion of the cover plate is received in the recess.

17. The battery according to claim 11, 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.

18. The battery according to any one of claims 1 to 2, characterized in that: The box body includes a first box wall located on the upper side of the battery cell, and the battery cell is fixed to the first box wall.

19. The battery according to claim 18, characterized in that The first box wall is used to serve as at least a part of the floor of the vehicle.

20. The battery according to claim 18, characterized in that The battery further includes a mounting beam, which is disposed on a side of the first box wall away from the battery cell.

21. The battery according to claim 20, characterized in that The mounting beam is used to mount a seat of a vehicle.

22. The battery according to any one of claims 1 to 2, characterized in that: The box body includes a second box wall, and the second box wall is arranged on the lower side of the battery cell.

23. The battery according to claim 22, characterized in that The second box wall is spaced apart from the battery cell.

24. The battery according to any one of claims 1 to 2, characterized in that: The box body includes a second box wall disposed on the lower side of the battery cell; The support member is bonded to the shell and the second box wall.

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

26. The battery according to claim 24, characterized in that The support member connects adjacent limiting beams.

27. The battery according to claim 8, 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.

28. The battery according to claim 24, characterized in that The support member has a cavity inside.

29. The battery according to any one of claims 1 to 2, 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.

30. The battery according to any one of claims 1 to 2, characterized in that: The expansion pressure of the battery cell in the thickness direction thereof is 0.5 MPa-2.4 MPa.

31. The battery according to any one of claims 1 to 2, 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 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 the thickness direction.

32. The battery according to claim 31, 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.

33. The battery according to claim 32, 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 on the first bus portion and connected through at least one bending portion. The second stacking portion is stacked on the second bus portion and connected through at least one bending portion.

34. The battery according to any one of claims 1 to 2, characterized in that: The box body comprises a plurality of limit beams, 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%.

35. The battery according to any one of claims 1 to 2, 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 .

36. The battery according to claim 35, 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 .

37. The battery according to any one of claims 1 to 2, 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 .

38. 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 1.25 g / cm 3 Up to 1.36g / cm 3 .

39. The battery according to any one of claims 1 to 2, characterized in that: The porosity of the negative electrode sheet is 27%-40%.

40. The battery according to any one of claims 1 to 2, characterized in that: The carbon-based material includes at least one of artificial graphite and natural graphite.

41. The battery according to any one of claims 1 to 2, 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%.

42. The battery according to claim 41, characterized in that The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% to 6%.

43. The battery according to claim 42, characterized in that The silicon-based material includes at least one of a silicon-oxygen compound and a silicon-carbon composite.

44. The battery according to any one of claims 1 to 2, 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.

45. The battery according to claim 44, 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.

46. ​​The battery according to claim 45, 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.

47. The battery according to claim 44, 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.

48. The battery according to claim 44, 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 negative electrode active material.

49. The battery according to claim 44, characterized in that The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm.

50. The battery according to claim 49, 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 μm-14.6 μm.

51. The battery according to any one of claims 1 to 2, characterized in that: The specific surface area of ​​the negative electrode active material is 0.5 m 2 / g-3m 2 / g.

52. The battery according to claim 51, characterized in that The specific surface area of ​​the negative electrode active material is 0.6 m 2 / g-1.2m 2 / g.

53. The battery according to any one of claims 1 to 2, 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, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

54. The battery according to any one of claims 1 to 2, characterized in that: The single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370mg / 1540 / mm 2 .

55. The battery according to claim 54, 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 .

56. The battery according to any one of claims 1-2, 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 .

57. The battery according to claim 56, 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 .

58. The battery according to any one of claims 1 to 2, characterized in that: The porosity of the positive electrode sheet is 25%-32%.

59. The battery according to any one of claims 1 to 2, characterized in that: The thickness of the positive electrode sheet is 0.13mm-0.2mm.

60. The battery according to any one of claims 1-2, 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.

61. The battery according to any one of claims 1 to 2, characterized in that: The volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm and 0.4µm≤Dv10≤0.7µm.

62. The battery according to any one of claims 1-2, characterized in that The battery cell includes an electrolyte contained in the housing.

63. The battery according to claim 62, characterized in that The conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm.

64. The battery according to claim 62, 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.

65. The battery according to claim 64, characterized in that The carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

66. The battery according to claim 64, 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.

67. The battery according to claim 62, 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.

68. The battery according to claim 62, characterized in that The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL≤ρ≤1.35 g / mL.

69. An electrical device, characterized in that: Comprising a battery according to any one of claims 1-68, wherein the battery is used to provide electrical energy.

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