Batteries and electrical devices

Abstract

Embodiments of the present application provide a battery and an electrical device. The battery includes a housing and a battery cell. The housing includes a first housing wall. The battery cell is housed within the housing and located below the first housing wall. The battery cell includes a housing, an electrode assembly, and a pressure relief mechanism. The housing is secured to the first housing wall, and the electrode assembly is housed within the housing. The housing includes a first end wall, which is located on a side of the electrode assembly away from the first housing wall. The pressure relief mechanism is disposed on the first end wall. At room temperature, the battery cell charges from 10% SOC to 80% SOC in 5 to 10.5 minutes.

Description

[0001] This application claims priority to PCT international application PCT / CN2024 / 102726, entitled “Batteries and Electrical Devices,” filed on June 28, 2024, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of batteries, and more particularly, to a battery and an electrical device. Background Art

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

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

[0005] The present application provides a battery and an electrical device, which can improve reliability.

[0006] In a first aspect, embodiments of the present application provide a battery comprising a housing and a battery cell. The housing includes a first wall. The battery cell is housed within the housing and located below the first wall. The battery cell comprises a housing, an electrode assembly, and a pressure relief mechanism. The housing is secured to the first wall, and the electrode assembly is housed within the housing. The housing includes a first end wall, which is located on a side of the electrode assembly away from the first wall. The pressure relief mechanism is disposed on the first end wall. At room temperature, the battery cell charges from 10% SOC to 80% SOC in 5 to 10.5 minutes.

[0007] The battery cells have fast charging capabilities, saving charging time and improving the user experience. During the fast charging process, even if a battery cell unexpectedly experiences thermal runaway, the high-temperature substances generated by the battery cell can be ejected downward through the pressure relief mechanism, thereby reducing the thermal impact on the upper side of the battery, reducing the risk of user injury, and improving the reliability of the battery and the electrical devices using it.

[0008] In some embodiments, the pressure relief mechanism and the first end wall are integrally formed. Integrating the pressure relief mechanism with the first end wall can save space required for connecting the pressure relief mechanism and the first end wall, provide more space for the pressure relief mechanism, improve pressure relief efficiency, and enhance battery reliability.

[0009] In some embodiments, the battery further includes a heat exchange element for exchanging heat with the outer casing. During charging, the heat exchange element can exchange heat with the outer casing of the battery cell, thereby controlling the temperature of the battery cell within an appropriate range, improving the cycle performance of the battery cell, reducing the risk of thermal runaway, and improving reliability.

[0010] In some embodiments, the housing further comprises a second end wall and a side wall, wherein the first end wall is disposed opposite the second end wall, the side wall connects the first and second end walls and surrounds the electrode assembly, and the second end wall is fixed to the first housing wall. The heat exchange element is disposed on the side wall. The pressure relief mechanism is disposed on the first end wall, and the second end wall is fixed to the first housing wall. Placing the heat exchange element on the side wall can reduce the risk of interference between the heat exchange element and the pressure relief mechanism and save vertical space.

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

[0012] In some embodiments, the electrode assembly includes a positive electrode sheet, the positive electrode sheet including a positive electrode current collector and a positive electrode film layer disposed between the positive electrode current collectors, the positive electrode film layer including a positive electrode active material, and the positive electrode active material including an olivine-structured lithium-containing phosphate. A first side wall of the battery cell is connected to the heat exchange element.

[0013] Lithium-containing phosphates with an olivine structure exhibit excellent cycling stability. Using these phosphates can reduce heat generation in battery cells during rapid charging, lowering the risk of thermal runaway. Using these phosphates can also reduce heat exchange requirements. In this embodiment, only one first sidewall of the battery cell is connected to the heat exchange element, reducing the number of heat exchange elements, saving space, and increasing the battery's energy density.

[0014] In some embodiments, a battery includes multiple battery cell groups and multiple heat exchange elements. The multiple battery cell groups are arranged along the thickness direction, and each battery cell group includes at least two battery cells arranged along a first direction. A heat exchange element is provided between every two battery cell groups. A single heat exchange element can simultaneously exchange heat with battery cells in two battery cell groups, thereby reducing the number of heat exchange elements and improving the battery's space utilization and energy density.

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

[0016] In some embodiments, the heat exchange element includes a heat conducting plate, wherein a flow channel for a heat exchange medium is provided inside the heat conducting plate. The heat exchange medium exchanges heat with the battery cells when flowing through the heat conducting plate.

[0017] In some embodiments, the heat exchange element further includes an insulating layer disposed on an outer surface of the heat conducting plate and configured to separate the heat conducting plate from the first sidewall. The insulating layer can insulate the heat conducting plate from the first sidewall, thereby increasing a creepage distance between the heat conducting plate and the first sidewall and reducing the risk of a short circuit.

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

[0019] In some embodiments, the outer shell is bonded to the first box wall via a second adhesive layer. The second adhesive layer secures the battery cell to the first box wall, thereby improving the stability of the battery cell. The second adhesive layer facilitates molding and simplifies the assembly process.

[0020] In some embodiments, the battery cell further includes a first electrode terminal disposed on the first end wall. The electrode assembly includes an electrode body and a first tab extending from the electrode body, and the first electrode terminal is electrically connected to the first tab. Positioning the first electrode terminal on the first end wall fully utilizes the space below the battery cell, reduces the risk of the first electrode terminal interfering with the connection between the outer casing and the first wall, and improves space utilization.

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

[0022] In some embodiments, the first end wall has an inner surface facing the electrode assembly, and the first electrode terminal does not extend beyond the inner surface in a direction approaching the electrode assembly. The first electrode terminal does not occupy the interior space of the outer casing, thereby improving the space utilization of the battery cell and increasing the energy density of the battery cell.

[0023] In some embodiments, the first electrode terminal includes a connecting portion having a through-hole formed therein, through which the first tab is inserted, and a portion of the first tab is located on a side of the connecting portion away from the electrode body and connected to the connecting portion. The provision of the through-hole allows the first tab to be extended outside the connecting portion, thereby reducing the distance between the connecting portion and the electrode body, improving internal space utilization of the battery cell, and increasing the energy density of the battery cell.

[0024] In some embodiments, the first electrode terminal includes a terminal body and a cover plate. The terminal body is fixed to the first end wall. A recess is provided on the side of the terminal body facing away from the electrode body, and the bottom wall of the recess serves as a connecting portion. The cover plate is provided on the side of the connecting portion facing away from the electrode body and covers the recess. The recess can accommodate a portion of the first tab, thereby improving space utilization. The cover plate separates the external space of the housing from the through-hole, achieving a seal and reducing the risk of electrolyte leakage.

[0025] In some embodiments, at least a portion of the cover plate is accommodated in the recess. Using the recess to accommodate the cover plate can improve space utilization.

[0026] In some embodiments, the first end wall has a width dimension of W1 mm and a width dimension of W2 mm for the portion of the first electrode terminal located outside the first end wall. W2 and W1 satisfy the following: 0.4≤W2 / W1≤1.

[0027] Setting W2 / W1 to greater than or equal to 0.4 allows the first electrode terminal to have a larger exposed area, increasing the connection area between the first electrode terminal and the current collector, improving current capacity, reducing temperature rise, improving battery cycle performance, and enhancing battery reliability. Setting W2 / W1 to less than or equal to 1 reduces the additional space occupied by the first electrode terminal in the width direction, improving space utilization.

[0028] In some embodiments, the box body further includes a second box wall, which is disposed below the battery cell and opposite to the first box wall. The second box wall can protect the battery cell from the bottom, thereby reducing the risk of the battery cell being impacted by external impurities and improving the reliability of the battery.

[0029] In some embodiments, the second wall is spaced apart from the battery cells. In the event of thermal runaway, the space between the second wall and the cells serves as a discharge channel, promptly discharging substances released from the cells to the outside of the box and reducing the risk of battery explosion. If the second wall is impacted, the space between the second wall and the cells acts as a barrier, reducing the impact force transmitted to the cells, lowering the risk of cell failure and improving battery reliability.

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

[0031] In some embodiments, the housing further includes a second wall disposed below the battery cells, the second wall being disposed opposite the first wall. A support member is bonded to the first end wall and the second wall. The support member connects the battery cells to the second wall, thereby increasing the overall structural strength of the battery.

[0032] In some embodiments, the elastic modulus of the support member is smaller than that of the second box wall. The smaller elastic modulus of the support member allows the support member to deform when the second box wall is subjected to an external impact, thereby reducing the force transmitted to the battery cell and lowering the risk of battery cell failure.

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

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

[0035] In some embodiments, the support member includes a metal strip and an insulating film covering the metal strip, with the insulating film separating the metal strip from the first end wall. The metal strip has high strength, which not only supports the battery cells but also effectively constrains the limiting beam. The insulating film insulates the metal strip from the battery cells, reducing the risk of short circuits.

[0036] In some embodiments, the support member has a cavity therein, which can reduce the weight of the support member.

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

[0038] In some embodiments, the battery further includes a mounting beam disposed on the side of the first wall facing away from the battery cells. Connected to the first wall, the mounting beam enhances the overall strength of the battery. The mounting beam also provides mounting locations for components of the electrical device, thereby reducing component count, improving integration, and simplifying assembly.

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

[0040] In some embodiments, the battery cell further includes a sampling element disposed on the outer casing for collecting the outer casing temperature. The sampling element can collect the outer casing temperature in real time to facilitate monitoring and regulating the battery cell temperature, reducing the risk of abnormal temperature rise in the battery cell during rapid charging and improving battery reliability.

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

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

[0043] The first busbar component has at least a double-layer structure, and both the first busbar layer and the second busbar layer of the first busbar component can transmit current. This allows the first busbar component to have a higher flow area, thereby reducing the heat generated by the first busbar component, improving the rapid charging capability of the battery, and reducing the risk of thermal runaway. On the premise that the flow area meets the requirements, setting the first busbar component to a double-layer structure can reduce the requirements for the thickness of the first busbar layer. The battery cell will expand during the cycle, thereby stretching the first busbar layer. The first busbar layer has a smaller 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 improving the reliability of the battery.

[0044] In some embodiments, the first busbar component includes at least one bend connecting the first busbar layer and the second busbar layer. The bend can connect the first busbar layer and the second busbar layer and transmit current between the first busbar layer and the second busbar layer, thereby improving the current carrying capacity of the first busbar component.

[0045] In some embodiments, the first busbar layer includes a first busbar portion, a second busbar portion, and a first buffer portion connecting the first and second busbar portions. The first and second busbar portions are arranged along the thickness direction and connected to different battery cells. The second busbar layer includes a first laminate portion, a second laminate portion, and a second buffer portion. The first laminate portion is laminated with the first busbar portion and connected via at least one bend. The second laminate portion is laminated with the second busbar portion and connected via at least one bend. The second buffer portion connects the first laminate portion and the second laminate portion.

[0046] During the battery's cycling, a portion of the current is transferred between the first laminate, the second buffer, and the second laminate, forming multiple conductive paths between the first and second busbars, thereby improving current handling capacity. During the cycling of a battery cell, the cell expands and exerts tension on the first busbar layer; both the first and second buffers deform to relieve stress, reducing the risk of failure in the connection between the first busbar layer and the battery cell.

[0047] In some embodiments, the box body further includes a plurality of limiting beams connected to the first box wall. The plurality of limiting beams are spaced apart along the thickness direction of the battery cells, with a plurality of battery cells disposed between adjacent limiting beams. The spacing between two adjacent limiting beams in the thickness direction is D1. In the thickness direction, the spacing between two adjacent limiting beams is D1, and the sum of the dimensions of all electrode assemblies stacked along the thickness direction between two adjacent limiting beams is D2. 85% ≤ D2 / D1 ≤ 92%.

[0048] Limiting D2 / D1 to less than or equal to 92% reduces the expansion pressure of battery cells, minimizes deformation of battery cells during rapid charging, reduces the risk of case cracking, and improves battery reliability. Limiting D2 / D1 to greater than or equal to 85% can improve space utilization in the thickness direction and increase the battery's energy density. Limiting D2 / D1 to 85%-92% can, to a certain extent, balance the expansion pressure of battery cells and the battery's energy density.

[0049] In some embodiments, the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and an isolation membrane 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 between the positive electrode current collectors. The positive electrode film layer includes a positive electrode active material. The positive electrode active material includes a lithium-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. The negative electrode active material includes a carbon-based material.

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

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

[0052] In some embodiments, the compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36g / cm 3 , optional 1.25g / cm 3 to 1.36g / 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. Moreover, because the negative electrode active material in the negative electrode film layer is relatively densely packed, the contact resistance between particles is small, which can reduce the resistance of the negative electrode sheet, thereby reducing heat generation and improving the battery's fast charging capability.

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

[0054] The porosity of the negative electrode sheet is greater than or equal to 27%, which can provide space for impurities generated by side reactions in the negative electrode sheet, slowing its expansion, reducing the expansion pressure of the battery cell, reducing battery cell deformation, improving the battery cell's cycle performance, and enhancing the battery cell's reliability during fast charging. The porosity of the negative electrode sheet is less than or equal to 40%, which can take into account the energy density of the battery cell.

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

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

[0057] Introducing silicon-based materials into the negative electrode sheet can both increase capacity and increase the expansion of the negative electrode sheet. Therefore, limiting the mass content of silicon in the negative electrode active material to 0.3% to 10% can, to a certain extent, balance the energy density and expansion of the battery cell, reduce the deformation of the battery cell, and improve the cycle performance and fast charging capability of the battery cell.

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

[0059] In some embodiments, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, the second negative electrode film layer being 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 including artificial graphite, and the second negative electrode active material including one or more of artificial graphite, natural graphite, and a silicon-based material.

[0060] The first negative electrode film layer and the second negative electrode film layer can be set differently, so as to take into account 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 tortuosity of ion transmission, reduce side reactions, and improve the fast charging performance of the battery cell.

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

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

[0063] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material.

[0064] The difference in particle size between the first negative electrode active material and the second negative electrode active material can improve the rapid charging performance of the battery cell. During rapid charging, the overpotential of the first negative electrode film layer is generally high, and the bottleneck of rapid charging lies primarily in the first negative electrode film layer. However, 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 rapid charging performance, and alleviate the problem of ion precipitation on the surface of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer. During charging, the pores can absorb expansion, reduce the amount of expansion of the negative electrode film layer, and improve the reliability of the battery cell during rapid charging.

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

[0066] The volume average particle size Dv50 of the first negative electrode active material is set to the above range. On the one hand, it can shorten the solid phase transmission path of lithium ions and improve the fast charging performance; on the other hand, the material is not easy to agglomerate during the preparation process, which can improve the stability of the material; on the other hand, the first negative electrode active material in the above volume average particle size range can be combined with the second negative electrode active material, which is conducive to constructing a gradient pore difference between the first negative electrode film layer and the second negative electrode film layer, reducing the tortuosity of lithium ion transmission, and improving the fast charging performance of the battery cell.

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

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

[0069] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g-3m 2 / g, optional 0.6m 2 / g-1.2m 2 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 capability of battery cells; the specific surface area of the negative electrode active material is limited to less than or equal to 3m 2 / g, which can reduce the side reactions of battery cells during storage and reduce the expansion pressure.

[0070] In some embodiments, the chemical formula of the olivine-structured lithium-containing phosphate is LiFe1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

[0071] In some embodiments, the single-side coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370mg / 1540 / mm 2 ; Optional: 240mg / 1540mm 2 Up to 330mg / 1540mm 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 also improve the energy density and charge rate performance of the battery cell.

[0072] In some embodiments, the compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80g / cm 3 ; Optional 2.55g / cm 3 -2.70g / cm 3 When the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and because the positive electrode active materials in the positive electrode film layer are relatively densely packed, 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.

[0073] In some embodiments, the porosity of the positive electrode sheet is 25%-32%. A porosity of 25% or greater can provide space for impurities generated by side reactions in the positive electrode sheet, reduce the expansion pressure of the battery cell, reduce deformation of the battery cell, and improve the cycle performance of the battery cell. A porosity of 32% or less can, to a certain extent, balance the energy density of the battery cell.

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

[0075] In some embodiments, the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer is 0.05-0.3. Limiting the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to greater than or equal to 0.05 can improve the current flow 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 less than or equal to 0.3 can reduce the capacity loss of the positive electrode sheet. The embodiment of the present application limits the ratio of the thickness of the positive electrode current collector to the thickness of the positive electrode film layer to 0.05 to 0.3, which can, to a certain extent, take into account the fast charging capability and energy density of the battery cell.

[0076] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1µm ≤ Dv50 ≤ 2µm and 0.4µm ≤ Dv10 ≤ 0.7µm. The relatively small particle size of the positive electrode active material shortens the lithium ion insertion and deintercalation pathway within the positive electrode active material, resulting in less heat generation. Furthermore, the particle size of the positive electrode active material is not excessively small, which reduces agglomeration during processing and preparation, resulting in stable performance of the positive electrode active material.

[0077] In some embodiments, the battery cell includes an electrolyte contained within a housing. During the charge and discharge process of the battery cell, active ions are intercalated and released back and forth between the positive electrode and the negative electrode, and the electrolyte serves to conduct the active ions between the positive electrode and the negative electrode.

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

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

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

[0081] In some embodiments, the carboxylate comprises R1-COO-R2, where R1 and R2 independently comprise an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms. The aforementioned chain carboxylate solvents have high electrical conductivity, which is beneficial for improving the fast charging capability of the battery cells.

[0082] In some embodiments, the electrolyte includes a lithium salt, including lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6). The molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) is 0.5 mol / L to 1.0 mol / L. These lithium salts are easily dissociated, facilitating the rapid migration of lithium ions. Furthermore, the electrolyte system is relatively stable and not easily decomposed, which can improve the cycling performance of the battery cells.

[0083] In some embodiments, the density ρ of the electrolyte at room temperature satisfies the following range: 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 high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0084] In a second aspect, an embodiment of the present application provides an electrical device, comprising a battery provided by any embodiment of the first aspect, wherein the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0086] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0087] Figure 2 A schematic diagram of a battery provided in some embodiments of the present application;

[0088] Figure 3 An exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0089] Figure 4 for Figure 2 An enlarged schematic diagram at the circle;

[0090] Figure 5 A partial cross-sectional schematic diagram of a battery provided in some embodiments of the present application;

[0091] Figure 6 A partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of the present application;

[0092] Figure 7 A partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of the present application;

[0093] Figure 8 A schematic cross-sectional view of a battery provided in some embodiments of the present application;

[0094] Figure 9 for Figure 8 An enlarged schematic diagram at the circle;

[0095] Figure 10 Schematic cross-sectional views of batteries provided in other embodiments of the present application;

[0096] Figure 11 for Figure 10 Enlarged schematic diagram at the box;

[0097] Figure 12 A schematic cross-sectional view of a battery support member provided in some embodiments of the present application;

[0098] Figure 13 A schematic diagram of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0099] Figure 14 A schematic diagram of a battery cell and a first busbar component provided in some embodiments of the present application;

[0100] Figure 15 for Figure 14 a schematic diagram of a first confluence component;

[0101] Figure 16 Schematic diagram of an explosion of a battery provided in some other embodiments of the present application;

[0102] Figure 17 A schematic cross-sectional view of a negative electrode sheet of a battery cell provided in some embodiments of the present application;

[0103] Figure 18 Schematic cross-sectional views of negative electrode sheets of battery cells provided in other embodiments of the present application;

[0104] Figure 19 Schematic cross-sectional views of the positive electrode sheets of battery cells provided in some other embodiments of the present application.

[0105] The following are the descriptions of the reference numerals:

[0106] 1. Vehicle; 2. Battery; 3. Controller; 4. Motor;

[0107] 10. Battery cell; 100. Battery cell group;

[0108] 11. Electrode assembly; 111. Positive electrode sheet; 1111. Positive electrode current collector; 1112. Positive electrode film; 112. Negative electrode sheet; 1121. Negative electrode current collector; 1122. Negative electrode film; 11221. First negative electrode film; 11222. Second negative electrode film; 113. Separator; 11a. Electrode body; 11b. First tab; 11c. Second tab.

[0109] 12. Housing; 121. Shell; 122. End cap; 1221. Outer surface; 1222. Inner surface; 1223. Electrode lead-out hole; 12a. First end wall; 12b. Second end wall; 12c. Side wall; 12d. First side wall; 12e. Second side wall;

[0110] 13. First electrode terminal; 131. Connecting portion; 1311. Through hole; 132. Terminal body; 133. Cover plate; 134. Recess;

[0111] 14. Second electrode terminal; 15. Pressure relief mechanism; 151. Weak portion; 152. Pressure relief portion; 153. Fixing portion; 16. Sampling member; 17. First fixing member; 18. Second fixing member;

[0112] 20. Box body; 21. First box wall; 22. Second box wall; 23. Frame; 24. Limiting beam;

[0113] 30. Heat exchange element; 31. Heat conducting plate; 311. Flow channel; 32. Insulation layer;

[0114] 40. First adhesive layer; 41. Second adhesive layer; 42. Third adhesive layer; 43. Insulation pad;

[0115] 50. Connecting pipe group;

[0116] 60. Support member; 61. Metal strip; 62. Insulation film; 63. Cavity;

[0117] 70. First busbar component; 71. First busbar layer; 711. First busbar portion; 712. Second busbar portion; 713. First buffer portion; 72. Second busbar layer; 721. First stacking portion; 722. Second stacking portion; 723. Second buffer portion; 73. Bend portion;

[0118] 80. Install beams;

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

[0120] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0121] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0122] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0123] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0124] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0125] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0126] " Range " disclosed in this application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. 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 can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In this application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, a numerical range of "0 to 5" indicates that all real numbers between "0 and 5" are listed herein, and "0 to 5" is merely an abbreviation for a combination of these values. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0127] The term "plurality" used in this application refers to two or more (including two).

[0128] Currently, market developments indicate that batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in aerospace and other fields. As battery applications continue to expand, market demand is also growing.

[0129] A battery generally refers to a single physical module that includes multiple battery cells to provide higher voltage and capacity. A battery cell may be the smallest unit that makes up a battery.

[0130] With the development of batteries, especially their widespread use in daily life, users expect batteries to charge faster to adapt to the fast-paced demands of modern life. However, during fast charging, the heat generated by battery cells increases, causing the battery cells to maintain a high temperature range throughout the charging process, increasing the risk of thermal runaway and affecting user safety.

[0131] In view of this, an embodiment of the present application provides a battery, which sets the pressure relief mechanism of the battery cell downward so that when the battery experiences thermal runaway due to rapid charging, the generated high-temperature material can be sprayed downward, thereby reducing the risk of user injury and improving the reliability of the battery.

[0132] The battery described in the embodiments of the present application is suitable for use in an electrical device that uses a battery. The electrical device may 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 may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0133] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0134] Figure 1 A schematic structural diagram of a vehicle provided for some embodiments of the present application.

[0135] like Figure 1 As shown, a battery 2 is provided inside the vehicle 1, and the battery 2 can be provided at the bottom, head, or tail of the vehicle 1. The battery 2 can be used to power the vehicle 1, for example, the battery 2 can be used as an operating power source for the vehicle 1.

[0136] 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, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0137] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0138] Figure 2 Schematic diagram of a battery provided for some embodiments of the present application.

[0139] Reference Figure 2 In some embodiments, the battery 2 includes a housing 20 and a plurality of battery cells 10 housed in the housing 20 .

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

[0141] Exemplarily, the battery cell 10 may be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, or the like.

[0142] As an example, the battery cell 10 may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. Prismatic battery cells include square-shell battery cells, blade-shaped battery cells, and polygonal prismatic batteries. Polygonal prismatic batteries are, for example, hexagonal prismatic batteries.

[0143] The multiple battery cells 10 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections within the multiple battery cells 10. The multiple battery cells 10 can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 10 can be housed within the housing 20. Alternatively, the multiple battery cells 10 can be first connected in series, in parallel, or in a hybrid connection to form a battery module, and then the multiple battery modules can be connected in series, in parallel, or in a hybrid connection to form an entire battery module, which can then be housed within the housing 20.

[0144] In some embodiments, the box 20 can be used as a part of the chassis structure of the vehicle. For example, part of the box 20 can become at least a part of the floor of the vehicle, or part of the box 20 can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0145] Figure 3 Schematic diagram of an explosion of a battery cell provided in some embodiments of the present application.

[0146] Reference Figure 3 In some embodiments, the battery cell 10 includes a housing 12 and an electrode assembly 11 housed in the housing 12 .

[0147] The housing 12 is a hollow structure, and its interior forms a space for accommodating the electrode assembly 11 and the electrolyte. 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 rectangular parallelepiped structure, a rectangular housing can be selected.

[0148] As an example, the housing 12 includes a shell 121 and an end cover 122 . The shell 121 has an opening, and the end cover 122 is used to cover the opening.

[0149] The housing 121 is a component used to cooperate with the end cover 122 to form an internal cavity of the battery cell 10. The formed internal cavity can be used to accommodate the electrode assembly 11, electrolyte and other components.

[0150] The housing 121 and the end cap 122 may be separate components. For example, an opening may be provided on the housing 121 , and the end cap 122 may be placed over the opening to form an internal cavity of the battery cell 10 .

[0151] The housing 121 can have various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 121 can be determined based on the specific shape and size of the electrode assembly 11. The housing 121 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this embodiment of the present application does not impose any particular limitation on this.

[0152] The shape of the end cap 122 can be adapted to the shape of the housing 121 to fit the housing 121. The material of the end cap 122 can be the same as or different from the material of the housing 121. Optionally, the end cap 122 can be made of a material with a certain degree of hardness and strength (e.g., copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). This makes the end cap 122 less likely to deform when subjected to compression or collision, thereby providing the battery cell 10 with greater structural strength and improved reliability.

[0153] The end cover 122 is connected to the housing 121 by welding, bonding, clamping or other methods.

[0154] The housing 121 may be open at one end or at both ends. In some examples, the housing 121 may be open at one end, with one end cap 122 provided to cover the housing 121. In other examples, the housing 121 may be open at both ends, with two end caps 122 provided to cover the two openings of the housing 121, respectively.

[0155] The electrode assembly 11 is a component where electrochemical reactions occur in the battery cell 10. One or more electrode assemblies 11 may be contained in the housing 121.

[0156] In some embodiments, the electrode assembly 11 includes a positive electrode sheet and a negative electrode sheet. During the charge and discharge process of the battery cell 10, active ions (such as lithium ions) are inserted into and removed from the positive electrode sheet and the negative electrode sheet.

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

[0158] In some embodiments, the electrode assembly 11 includes an electrode body 11a, a first electrode tab 11b, and a second electrode tab 11c. The first electrode tab 11b and the second electrode tab 11c extend from the electrode body 11a. The first electrode tab 11b and the second electrode tab 11c have opposite polarities. In other words, one of the first electrode tab 11b and the second electrode tab 11c is a positive electrode tab and the other is a negative electrode tab.

[0159] As an example, the portion of the positive electrode sheet with active material, the portion of the negative electrode sheet with active material, and the separator constitute the electrode assembly 11. The portion of the positive electrode sheet without active material constitutes the positive tab, and the portion of the negative electrode sheet without active material constitutes the negative tab. The positive and negative tabs can be located together at one end of the electrode body 11a or separately at both ends of the electrode body 11a.

[0160] In some embodiments, the electrode assembly 11 is a wound structure in which the positive electrode sheet and the negative electrode sheet are wound into a wound structure.

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

[0162] 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 can be alternately stacked.

[0163] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

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

[0165] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0166] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

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

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

[0169] As an example, the first electrode terminal 13 may be an independently formed component, which is mounted on the housing 12 . Alternatively, the first electrode terminal 13 may also be a part of the housing 12 .

[0170] As an example, the second electrode terminal 14 may be an independently formed component, which is mounted on the housing 12. Alternatively, the second electrode terminal 14 may also be a part of the housing 12.

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

[0172] In some embodiments, the battery cell 10 further includes a pressure relief mechanism 15. This mechanism significantly impacts the reliability of the battery cell 10. For example, short circuits, overcharging, and other conditions can cause thermal runaway within the battery cell 10, leading to a sudden increase in pressure. In such cases, activation of the pressure relief mechanism 15 releases internal pressure, reducing the risk of explosion or fire in the battery cell 10.

[0173] For example, the pressure relief mechanism 15 is a component or element that is activated to release internal gas when the internal pressure or temperature of the battery cell 10 reaches a predetermined threshold. This threshold value varies depending on the design requirements. The threshold value may depend on the material of one or more of the positive electrode sheet, negative electrode sheet, electrolyte, and separator in the battery cell 10.

[0174] The pressure relief mechanism 15 can take the form of an explosion-proof valve, an air valve, a pressure relief valve, or a safety valve, and can specifically be a pressure-sensitive element or structure. Specifically, when the internal pressure of the battery cell 10 reaches a predetermined threshold, the pressure relief mechanism 15 activates, or a weak area within the pressure relief mechanism 15 ruptures, thereby forming an opening or passage through which the internal pressure can be released. Alternatively, the pressure relief mechanism 15 can be a temperature-sensitive element or structure. Specifically, when the internal temperature of the battery cell 10 reaches a predetermined threshold, the pressure relief mechanism 15 activates, thereby forming an opening or passage through which the internal pressure can be released.

[0175] When the battery cell 10 thermally runs away, the emissions from the battery cell 10 include but are not limited to: electrolyte, dissolved or split positive and negative electrodes, separator fragments, high-temperature and high-pressure gas generated by the reaction, flames, etc.

[0176] In some embodiments, the pressure relief mechanism 15 is disposed on the housing 12. For example, the pressure relief mechanism 15 can be disposed on the housing 121 or on the end cover 122.

[0177] Figure 4 for Figure 2 An enlarged schematic diagram at the circle; Figure 5 A schematic partial cross-sectional view of a battery provided in some embodiments of the present application.

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

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

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

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

[0182] As an example, when the battery 2 is installed in an electrical device, the first box wall 21 may be located above the battery cell 10 along the vertical direction Z. During the production and transportation of the battery 2 , the first box wall 21 is not required to be located above the battery cell 10 .

[0183] 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 can be formed by connecting multiple independently formed components.

[0184] The first end wall 12 a may be an end cover 122 or a wall of the housing 121 .

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

[0186] In some examples, the pressure relief mechanism 15 and the first end wall 12a can be independently formed components, connected by welding, bonding, or other means. For example, the first end wall 12a may be provided with a pressure relief hole that extends through the first end wall 12a. The pressure relief mechanism 15 is mounted on the first end wall 12a and covers the pressure relief hole, thereby separating the space inside and outside the first end wall 12a. In alternative embodiments, the pressure relief mechanism 15 and the first end wall 12a may also be integrally formed.

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

[0188] For example, 100% SOC and 0% SOC are defined as follows: Charging the battery cell 10 at a constant current charge rate of 0.33C to the battery charge upper limit voltage, followed by constant voltage charging to 0.05C, corresponds to a 100% SOC state for the battery cell; discharging the battery cell 10 at a constant current discharge rate of 0.33C to the cutoff voltage corresponds to a 0% SOC state for the battery cell. For example, the battery charge upper limit voltage may be 3.8V, and the battery discharge cutoff voltage may be 2.0V.

[0189] 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.

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

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

[0192] Charge from 10% SOC to 15% SOC at 5.0C constant current;

[0193] Charge from 15% SOC to 20% SOC at 5.0C constant current;

[0194] Charge from 20% SOC to 25% SOC at 5.0C constant current;

[0195] Charge from 25% SOC to 30% SOC at 5.0C constant current;

[0196] Charge from 30% SOC to 35% SOC at 5.0C constant current;

[0197] Charge from 35% SOC to 40% SOC at 5.0C constant current;

[0198] Charge from 40% SOC to 45% SOC at 4.6C constant current;

[0199] Charge from 45% SOC to 50% SOC at 4.3C constant current;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0214] In some embodiments, at room temperature, when the battery cell 10 is charged from 10% SOC to 80% SOC, the charging current may be 2C-6C, optionally 2.7C-5C. During the charging process, the charging current may vary according to the SOC of the battery cell 10 .

[0215] In some embodiments, the battery cell 10 is a lithium-ion battery cell. After the battery cell 10 is cycled 20 times according to the charging and discharging strategies, the negative electrode sheet of the battery cell 10 is disassembled and the lithium deposition area of the negative electrode sheet is observed and measured. The ratio of the lithium deposition area to the total area of the negative electrode sheet is less than 2%.

[0216] As an example, the discharge strategy adopts discharging to 2.0V at a constant current of 0.33C.

[0217] As an example, the charging strategy may be:

[0218] Charge from 0% SOC to 5% SOC at 5.0C constant current;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0239] The battery cell 10 of the embodiment of the present application can be charged from 10% SOC to 80% SOC in 10.5 minutes with no or minimal lithium deposition, demonstrating excellent fast charging capability. For example, if the ratio of the area of the lithium deposition region to the total area of the negative electrode sheet is less than 0.05%, it is considered that no lithium deposition occurs. If the ratio of the area of the lithium deposition region to the total area of the negative electrode sheet is less than 2% and greater than or equal to 0.05%, it is considered that minimal lithium deposition occurs.

[0240] In some embodiments, the pressure relief mechanism 15 includes a weak portion 151. The weak portion 151 is a portion of the pressure relief mechanism 15 with relatively low strength, and is a portion of the pressure relief mechanism 15 that is easily broken, shattered, torn, or opened.

[0241] In some examples, the present application may provide grooves, notches, or other structures in a predetermined region of the pressure relief mechanism 15 to reduce the local strength of the pressure relief mechanism 15, thereby forming a weak portion 151 on the pressure relief mechanism 15. For example, a thinning process may be performed on the predetermined region of the pressure relief mechanism 15, and the thinned portion of the pressure relief mechanism 15 forms the weak portion 151. In other examples, a material treatment may be performed on the predetermined region of the pressure relief mechanism 15 to make the strength of the region weaker than that of other regions. In other words, the region serves as the weak portion 151.

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

[0243] Exemplarily, the pressure relief mechanism 15 includes a pressure relief portion 152, a weakened portion 151 and a fixed portion 153. The weakened portion 151 is arranged along the outer periphery of the pressure relief portion 152 and connects the pressure relief portion 152 and the fixed portion 153. The fixed portion 153 can be used to be fixedly connected to the first end wall 12a.

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

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

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

[0247] By integrally forming the pressure relief mechanism 15 and the first end wall 12 a , conventional welding steps can be omitted, thereby reducing the thermal impact on the weak portion 151 of the pressure relief mechanism 15 and improving the stability of the pressure relief mechanism 15 .

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

[0249] As an example, the first end wall 12 a may be a bottom wall of the housing 121 .

[0250] In some embodiments, the battery 2 further includes a heat exchange element 30 , which is used to exchange heat with the housing 12 .

[0251] There may be one or more heat exchange elements 30. As an example, the battery cell 10 may exchange heat with only one heat exchange element 30, or may exchange heat with multiple heat exchange elements 30 at the same time.

[0252] The heat exchange element 30 may directly exchange heat with the housing 12 or indirectly exchange heat with the housing 12 via other heat conducting structures.

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

[0254] As an example, the heat exchange element 30 may be an independently formed component disposed in the housing 20 , or may be integrated with the housing 20 .

[0255] The heat exchange element 30 may be an integrally formed component, or may be formed by assembling a plurality of independently formed subcomponents.

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

[0257] In some embodiments, the shell 12 also includes a second end wall 12b and a side wall 12c, the first end wall 12a is arranged opposite to the second end wall 12b, the side wall 12c connects the first end wall 12a and the second end wall 12b and surrounds the electrode assembly 11, and the second end wall 12b is fixed to the first box wall 21.

[0258] As an example, the side wall 12c may be a cylindrical structure. For example, if the battery cell 10 is a square-shell battery cell, the side wall 12c may be a square-cylinder structure; for example, if the battery cell 10 is a cylindrical battery cell, the side wall 12c may be a cylindrical structure.

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

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

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

[0262] In some embodiments, the heat exchange member 30 is disposed on the side wall 12c and is used to exchange heat with the side wall 12c.

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

[0264] In some embodiments, the sidewalls 12c include two first sidewalls 12d and two second sidewalls 12e. The two first sidewalls 12d are disposed opposite each other along the thickness direction X of the battery cell 10, and the two second sidewalls 12e are disposed opposite each other along a first direction Y perpendicular to the thickness direction X. Each second sidewall 12e connects two first sidewalls 12d. At least one first sidewall 12d of the battery cell 10 is connected to the heat exchange element 30.

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

[0266] The first side wall 12d is the largest wall of the outer shell 12. Connecting the first side wall 12d to the heat exchange element 30 can increase the heat exchange area and improve the heat exchange efficiency, thereby reducing the temperature rise of the battery cell 10 during fast charging, reducing the risk of thermal runaway, and improving reliability.

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

[0268] In some embodiments, the electrode assembly 11 includes a positive electrode sheet, which includes a positive electrode current collector and a positive electrode film layer disposed between the positive electrode current collectors. The positive electrode film layer includes a positive electrode active material, which includes an olivine-structured lithium-containing phosphate. A first sidewall 12d of the battery cell 10 is connected to the heat exchange element 30.

[0269] Lithium-containing phosphates with an olivine structure exhibit excellent cycling stability. Using such a structure can reduce heat generation in the battery cell 10 during rapid charging, lowering the risk of thermal runaway in the battery cell 10. Using such a structure can also reduce heat exchange requirements. In this embodiment, only the first sidewall 12d of the battery cell 10 is connected to the heat exchange element 30, reducing the number of heat exchange elements 30, saving space, and increasing the energy density of the battery 2.

[0270] 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 may also be connected to the two heat exchange elements 30 respectively to improve the temperature control effect.

[0271] In some embodiments, the battery 2 includes a plurality of battery cell groups 100 , each of which includes at least two battery cells 10 arranged along a first direction Y.

[0272] Exemplarily, the plurality of battery cells 10 of the battery 2 are arranged in an array within the box 20 .

[0273] The numbers of battery cells 10 in adjacent battery cell groups 100 may be the same or different.

[0274] In some embodiments, a heat exchange element 30 is provided between every two battery cell groups 100 .

[0275] The number of battery cell groups 100 may be an even number or an odd number.

[0276] In some examples, the number of battery cell groups 100 is 2n, where n is a positive integer. Along the thickness direction X, a heat exchange element 30 is disposed between the 2k-1th battery cell group 100 and the 2kth battery cell group 100, where k is a natural number from 1 to n. The number of heat exchange elements 30 can be n.

[0277] In other examples, the number of battery cell groups 100 is 2n+1, where n is a positive integer. Along the thickness direction X, a heat exchange element 30 is disposed between the 2k-1th battery cell group 100 and the 2kth battery cell group 100, where k is a natural number from 1 to n. The number of heat exchange elements 30 can be n+1, with one heat exchange element 30 corresponding to the 2n+1th battery cell group 100.

[0278] In the embodiment of the present application, one heat exchange element 30 can simultaneously exchange heat with the battery cells 10 of two battery cell groups 100 , which can reduce the number of heat exchange elements 30 and improve the space utilization and energy density of the battery 2 .

[0279] In some embodiments, there are multiple heat exchange elements 30 , and the multiple heat exchange elements 30 are arranged along the thickness direction X. Two battery cell groups 100 are disposed between adjacent heat exchange elements 30 .

[0280] 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 element 30 .

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

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

[0283] In some embodiments, the heat exchange element 30 includes a heat conducting plate 31 , and a flow channel 311 for a heat exchange medium to flow is provided inside the heat conducting plate 31 . The heat exchange medium exchanges heat with the battery cell 10 when flowing through the heat conducting plate 31 .

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

[0285] In some embodiments, the heat conducting plate 31 is a metal plate or a non-metal plate.

[0286] In some embodiments, the heat exchange element 30 further includes an insulating layer 32 . The insulating layer 32 is disposed on the outer surface of the heat conducting plate 31 and is used to separate the heat conducting plate 31 from the first side wall 12 d .

[0287] The insulating layer 32 can insulate the heat conducting plate 31 from the first side wall 12 d , thereby increasing the creepage distance between the heat conducting plate 31 and the first side wall 12 d and reducing the risk of short circuit.

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

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

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

[0291] In some embodiments, at least a portion of the heat exchange element 30 is configured to be deformable in the thickness direction X. The battery cell 10 expands during cycling, and the heat exchange element 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.

[0292] In some embodiments, the battery 2 further includes a connecting tube group 50 for connecting the plurality of heat exchange elements 30. The connecting tube group 50 can communicate with the flow channels 311 of the plurality of heat exchange elements 30, thereby enabling the flow of heat exchange medium in the flow channels 311.

[0293] Exemplarily, the connecting pipe group 50 includes an inlet pipe and an outlet pipe, the inlet pipe is connected to the flow channels 311 of the plurality of heat exchange elements 30 , and the outlet pipe is connected to the flow channels 311 of the plurality of heat exchange elements 30 .

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

[0295] In some embodiments, the battery cell 10 further includes a sampling member 16 disposed on the housing 12 , and the sampling member 16 is used to collect the temperature of the housing 12 .

[0296] The sampling member 16 may be disposed in the housing 12 or outside the housing 12 .

[0297] The sampling element 16 can collect the temperature of the housing 12 in real time to monitor and adjust the temperature of the battery cell 10, reduce the risk of abnormal temperature rise of the battery cell 10 during fast charging, and improve the reliability of the battery 2.

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

[0299] In some embodiments, there are multiple sampling members 16 , and the multiple sampling members 16 can be disposed at locations of the battery cell 10 where the temperature is higher during the cycle process.

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

[0301] In some embodiments, the housing 12 is bonded to the first box wall 21 via a second adhesive layer 41. The second adhesive layer 41 can secure the battery cell 10 to the first box wall 21, thereby improving the stability of the battery cell 10. The second adhesive layer 41 facilitates molding and simplifies the assembly process.

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

[0303] Disposing the first electrode terminal 13 on the first end wall 12 a can fully utilize the space below the battery cell 10 , reduce the risk of the first electrode terminal 13 interfering with the connection between the housing 12 and the first box wall 21 , and improve space utilization.

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

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

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

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

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

[0309] In some embodiments, the projection area 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 -600mm 2 , 200mm is optional 2 , 250mm 2 , 300mm 2, 350mm 2 , 400mm 2 , 450mm 2 , 500mm 2 , 550mm 2 or 600mm 2 .

[0310] Illustratively, 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.

[0311] The portion of first electrode terminal 13 located outside first end wall 12a has a larger area, which increases the flow area, reduces heat generation, and lowers the temperature rise of first electrode terminal 13 during battery 2 cycling, thereby improving reliability. The large exposed area of first electrode terminal 13 increases the heat dissipation efficiency of first electrode terminal 13.

[0312] In some embodiments, the first end wall 12a has a width dimension of W1 mm and a width dimension of W2 mm for the portion of the first electrode terminal 13 located outside the first end wall 12a. W2 and W1 satisfy: 0.4≤W2 / W1≤1.

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

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

[0315] Setting W2 / W1 to be greater than or equal to 0.4 allows the first electrode terminal 13 to have a larger exposed area, increasing the connection area between the first electrode terminal 13 and the current collector, improving current flow capacity, reducing temperature rise, improving the cycle performance of the battery 2, and enhancing the reliability of the battery 2. Setting W2 / W1 to be less than or equal to 1 can reduce the additional space occupied by the first electrode terminal 13 in the width direction, thereby improving space utilization.

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

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

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

[0319] Figure 6 Schematic partial cross-sectional views of battery cells provided in some other embodiments of the present application.

[0320] In some embodiments, reference Figure 6 The first end wall 12 a has an inner surface 1222 facing the electrode assembly 11 , and the first electrode terminal 13 does not extend beyond the inner surface 1222 in a direction approaching the electrode assembly 11 .

[0321] In the embodiment of the present application, the first electrode terminal 13 may not occupy the internal space of the housing 12 , thereby improving the space utilization of the battery cell 10 and enhancing the energy density of the battery cell 10 .

[0322] In some embodiments, the first end wall 12a includes an electrode lead-out hole 1223 , and 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 .

[0323] 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 12 a .

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

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

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

[0327] Figure 7 Schematic partial cross-sectional views of battery cells provided in some further embodiments of the present application.

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

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

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

[0331] 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 and includes a connecting portion 131. The cover plate 133 is disposed on a side of the connecting portion 131 away from the electrode body 11a and is connected to the terminal body 132. The cover plate 133 separates the through hole 1311 from the external space of the battery cell 10.

[0332] In some embodiments, a recess 134 is provided on the side of the terminal body 132 away from the electrode body 11 a , and the bottom wall of the recess 134 is the connection portion 131 . A cover plate 133 is provided on the side of the connection portion 131 away from the electrode body 11 a and is used to cover the recess 134 .

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

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

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

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

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

[0338] Figure 8 A schematic cross-sectional view of a battery provided in some embodiments of the present application; Figure 9 for Figure 8 Enlarged diagram of the circle.

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

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

[0341] The second box wall 22 can protect the battery cells 10 from the bottom side to reduce the risk of the battery cells 10 being impacted by external impurities and improve the reliability of the battery 2 .

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

[0343] In some embodiments, the housing 20 further includes a frame 23, with the first wall 21 and the second wall 22 respectively located above and below the frame 23. The first wall 21, the second wall 22, and the frame 23 define an interior space for accommodating the battery cells 10 and the heat exchange element 30.

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

[0345] In the event of thermal runaway of a battery cell 10, the space between the second wall 22 and the battery cell 10 serves as a discharge channel, promptly discharging substances released from the battery cell 10 outside the housing 20 and reducing the risk of explosion of the battery 2. In the event of an external impact on the second wall 22, the space between the second wall 22 and the battery cell 10 acts as a barrier, reducing the impact force transmitted to the battery cell 10, lowering the risk of battery cell 10 failure and improving the reliability of the battery 2.

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

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

[0348] There may be one or more supporting members 60 .

[0349] As an example, 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 .

[0350] 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 .

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

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

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

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

[0355] The elastic modulus of the support member 60 is relatively small. When the second box wall 22 is subjected to an external impact, the support member 60 can be deformed to reduce the force transmitted to the battery cell 10 and reduce the risk of failure of the battery cell 10 .

[0356] In some embodiments, the support member 60 has a cavity therein, which can reduce the weight of the support member 60 and improve the compressibility of the support member 60.

[0357] In some embodiments, there are a plurality of support members 60 , which extend along a thickness direction X of the battery cell 10 , and the plurality of support members 60 are spaced apart along a first direction Y.

[0358] In some embodiments, the first end wall 12 a is supported by two support members 60 at both ends along the first direction Y. For example, 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 .

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

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

[0361] Figure 10 Schematic cross-sectional views of batteries provided in other embodiments of the present application; Figure 11 for Figure 10 Enlarged schematic diagram at the box; Figure 12 A schematic cross-sectional view of a battery support member provided in some embodiments of the present application; Figure 13 Schematic diagram of an electrode assembly of a battery cell provided in some embodiments of the present application.

[0362] Reference Figures 10 to 13 In some embodiments, the box body 20 further includes a plurality of limiting beams 24 connected to the first box wall 21 . The plurality of limiting beams 24 are spaced apart along the thickness direction X of the battery cell 10 , and a plurality of battery cells 10 are disposed between adjacent limiting beams 24 .

[0363] There may be two or more limiting beams 24. As an example, a battery cell 10 is disposed between any two adjacent limiting beams 24.

[0364] The limiting beams 24 can be used to limit the expansion and deformation of the battery cell 10 in the thickness direction X. The limiting beams 24 can directly abut the battery cell 10 in the thickness direction X; alternatively, other components can be provided between the limiting beams 24 and the battery cell 10, that is, the limiting beams 24 limit the expansion of the battery cell 10 through the components.

[0365] The limiting beam 24 has a high anti-deformation capability, and can provide effective constraints on the battery cell 10 in the thickness direction X, reduce the maximum expansion of the battery cell 10 in the thickness direction X, and improve the cycle performance of the battery cell 10 .

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

[0367] In some embodiments, the support member 60 connects adjacent limiting beams 24 .

[0368] There may be one or more supporting members 60 .

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

[0370] The support member 60 is a strip structure, a line structure, a beam structure or other structures. Exemplarily, the support member 60 extends along the thickness direction X of the battery cell 10 .

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

[0372] In some embodiments, the support member 60 may apply a pre-tightening force to the adjacent limiting beams 24 .

[0373] In some embodiments, the support member 60 is a strip-shaped structure. The strip-shaped structure is low-cost and occupies little space. Using the strip-shaped support member 60 can improve the space utilization inside the battery 2 and increase the energy density of the battery 2.

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

[0375] Exemplarily, the metal strip 61 comprises a steel strip.

[0376] The metal strip 61 has high strength and can support the battery cell 10 while effectively restraining the limiting beam 24. The insulating film 62 can insulate the metal strip 61 from the battery cell 10 to reduce the risk of short circuit.

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

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

[0379] 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 to increase the connection strength between the battery cell 10 and the housing 20, reduce the shaking of the battery cell 10 relative to the housing 20 when the battery 2 is impacted, and improve the reliability and stability of the battery 2.

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

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

[0382] In some embodiments, the support member 60 and the limiting beam 24 may be connected by, but not limited to, bolt connection, snap connection, or other detachable connection methods.

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

[0384] 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.

[0385] As an example, the expansion pressure of the battery cell 10 can be measured as follows:

[0386] At an ambient temperature of 45°C, discharge the battery cells at a constant current rate of 1C to 2.0V.

[0387] The battery cell is clamped between two clamping plates, wherein 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);

[0388] At an ambient temperature of 45°C, charge the battery cells to 3.8V at a constant current rate of 0.8C, and detect and record the pressure exerted by the battery cells on the clamping plate.

[0389] The battery cells were cycled and discharged according to the above charging and discharging strategies until the battery cells reached 70% SOH (i.e., the capacity retention rate of the battery cells = the discharge capacity of the battery cells / the nominal capacity of the battery cells = 70%), and the maximum pressure exerted by the battery cells on the clamping plate was recorded;

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

[0391] The expansion pressure of the battery cell 10 is related to the density of the electrode assembly 11. The battery cell 10 has an expansion pressure of greater than or equal to 0.5 MPa in the thickness direction X, thereby improving the density 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 and deformation of the separator of the electrode assembly 11, and reduce the risk of local increase in the distance between the positive and negative electrode sheets, reduce polarization, and improve the cycling performance of the battery cell 10.

[0392] The embodiment of the present application limits the expansion pressure of the battery cell 10 in the thickness direction X to 0.5 MPa-2.4 MPa to reduce the expansion deformation of the battery cell 10 during rapid charging, improve the cycle performance of the battery cell 10, reduce the risk of cracking of the box 20, and improve the reliability of the battery 2.

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

[0394] In some embodiments, the box body 20 further includes a plurality of limiting beams 24 connected to the first box wall 21. The plurality of limiting beams 24 are spaced apart along the thickness direction X of the battery cells 10, with a plurality of battery cells 10 disposed between adjacent limiting beams 24. The spacing between two adjacent limiting beams 24 in the thickness direction X is D1. In the thickness direction X, the spacing between two adjacent limiting beams 24 is D1, and the sum of the dimensions of all electrode assemblies 11 stacked along the thickness direction X and located between two adjacent limiting beams 24 is D2. 85% ≤ D2 / D1 ≤ 92%.

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

[0396] 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 to be D1; the removed battery cell 10 is disassembled and the electrode assembly 11 is taken out, and the thicknesses of M1×M2 electrode assemblies 11 arranged in the thickness direction X are measured and summed to obtain D2.

[0397] Exemplarily, when the battery cell 10 is at % SOC, the dimension of the electrode assembly 11 along the thickness direction X is T; D2 = M1×M2×T.

[0398] D2 / D1 is related to the expansion pressure of the battery cell 10. In the embodiment of the present application, D2 / D1 is limited to less than or equal to 92% to reduce the expansion pressure of the battery cell 10, minimize deformation of the battery cell 10 during rapid charging, reduce the risk of cracking of the casing 20, and improve the reliability of the battery 2. Limiting D2 / D1 to greater than or equal to 85% can improve space utilization in the thickness direction X and increase the energy density of the battery 2. Limiting D2 / D1 to 85%-92% can, to a certain extent, balance the expansion pressure of the battery cell 10 and the energy density of the battery 2.

[0399] Figure 14 A schematic diagram of a battery cell and a first busbar component provided in some embodiments of the present application; Figure 15 for Figure 14 Schematic diagram of the first busbar component.

[0400] Reference Figure 14 and Figure 15 In some embodiments, the battery 2 includes a plurality of battery cells 10 and a plurality of busbars that electrically connect the plurality of battery cells 10 .

[0401] The plurality of busbar components can connect the plurality of battery cells 10 in series, in parallel, or in mixed series.

[0402] The multiple confluence components may have the same structure or different structures.

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

[0404] All of the plurality of merging members may be the first merging members 70 , or some of them may be the first merging members 70 .

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

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

[0407] Assuming the flow area meets the requirements, configuring the first busbar component 70 as a double-layer structure can reduce the thickness requirement for the first busbar layer 71. The battery cells 10 expand during cycling, thereby stretching the first busbar layer 71. The first busbar layer 71 has a relatively small thickness and easily deforms to accommodate the deformation of the battery cells 10. This reduces the risk of rupture at the connection between the battery cells 10 and the first busbar layer 71, thereby improving the reliability of the battery 2.

[0408] In some embodiments, the thickness of the first bus layer 71 is 1 mm to 2.5 mm. Optionally, the thickness of the first bus layer 71 is 1.2 mm to 1.8 mm. As an example, the thickness of the first bus 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 embodiment of the present application, the thickness of the first bus layer 71 is selected according to the expansion pressure of the battery cell 10, which can take into account the flow capacity of the first bus layer 71 and the deformability of the first bus layer 71 to a certain extent, thereby improving the fast charging capability and reliability of the battery 2.

[0409] In some embodiments, the second bus layer 72 has a thickness of 1 mm to 2.5 mm. Alternatively, the second bus layer 72 has a thickness of 1.2 mm to 1.8 mm. By way of example, the second bus layer 72 has a thickness of 1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, or 2.5 mm.

[0410] The thickness of the second busbar layer 72 can be selected based on the thickness of the first busbar layer 71 and the current flow capacity of the battery to the first busbar component. For example, when the thickness of the first busbar layer 71 is relatively small, the second busbar layer 72 can be thicker than the first busbar layer 71 to improve the current flow capacity of the first busbar component.

[0411] In some embodiments, the first busbar 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 the two battery cells 10 in series. Alternatively, the first busbar layer 71 is connected to the first electrode terminals 13 of two battery cells 10 to connect the two battery cells 10 in parallel.

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

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

[0414] There may be one or more bending portions 73 .

[0415] The bent portion 73 can connect the first bus layer 71 and the second bus layer 72 and transmit current between the first bus layer 71 and the second bus layer 72 , thereby improving the current carrying capacity of the first bus component 70 .

[0416] In some embodiments, the first busbar layer 71 includes a first busbar portion 711 , a second busbar portion 712 , and a first buffer portion 713 connecting the first busbar portion 711 and the second busbar portion 712 . The first busbar portion 711 and the second busbar portion 712 are arranged along the thickness direction X and connected to different battery cells 10 .

[0417] For example, the first busbar 711 may be connected to the electrode terminals (first electrode terminals 13 or second electrode terminals 14 ) of one or more battery cells 10 , and the second busbar 712 may be connected to the electrode terminals (first electrode terminals 13 or second electrode terminals 14 ) of one or more battery cells 10 .

[0418] During the cycle of the battery cell 10, the battery cell 10 expands and applies tension to the first bus layer 71; the first buffer portion 713 can release stress by deformation, thereby reducing the force at the connection between the first bus portion 711 and the battery cell 10 and the force at the connection between the second bus portion 712 and the battery cell 10, reducing the risk of failure of the connection between the first bus layer 71 and the battery cell 10.

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

[0420] In some embodiments, the first buffer portion 713 includes an arched structure.

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

[0422] In some embodiments, the second bus layer 72 includes a first laminated portion 721, a second laminated portion 722, and a second buffer portion 723. The first laminated portion 721 is laminated with the first bus portion 711 and connected via at least one bending portion 73. The second laminated portion 722 is laminated with the second bus portion 712 and connected via at least one bending portion 73. The second buffer portion 723 connects the first laminated portion 721 and the second laminated portion 722.

[0423] Illustratively, the first stacking portion 721 is attached to the first confluence portion 711 , and the second stacking portion 722 is attached to the second confluence portion 712 .

[0424] During the cycle of battery 2, a portion of the current can be transmitted between the first busbar 711 and the second busbar 712 through the first stack portion 721, the second buffer portion 723, and the second stack portion 722, forming multiple conductive paths between the first busbar 711 and the second busbar 712, thereby improving the current flow capacity.

[0425] During the cycle of the battery cell 10 , the battery cell 10 expands and applies tension to the first busbar layer 71 ; both the first buffer portion 713 and the second buffer portion 723 can release stress by deformation, thereby reducing the risk of connection failure between the first busbar layer 71 and the battery cell 10 .

[0426] In some embodiments, the second buffer portion 723 at least partially overlaps with the first buffer portion 713, so that the deformation areas of the first buffer portion 713 and the second buffer portion 723 are close to each other, thereby reducing the risk of the first buffer portion 713 and the second buffer portion 723 interfering with other parts during deformation.

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

[0428] In some embodiments, the second bus layer 72 is located under the first bus layer 71 .

[0429] In some embodiments, the multiple busbars further include a second busbar (not shown) with a single-layer structure. In battery 2, the expansion of battery cells 10 at different locations may vary. For battery cells 10 with less expansion, a second busbar with a single-layer structure can be used. Compared to the first busbar 70, the second busbar offers a simpler structure, is easier to manufacture, and can save costs. The thickness of the second busbar is greater than that of the first and second busbar layers 71, 72, to ensure that its current carrying capacity meets the requirements.

[0430] Figure 16 Schematic diagram of an explosion of a battery provided in some other embodiments of the present application.

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

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

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

[0434] In some embodiments, the mounting beam 80 is used to mount vehicle seats. This embodiment of the present application can improve space utilization in the vehicle. The mounting beam 80, combined with the first compartment wall 21, frees up additional space in the vertical direction Z, thereby further increasing the size of the battery cell 10 in the vertical direction Z and improving the energy density of the battery 2.

[0435] Figure 17 A schematic cross-sectional view of a negative electrode sheet of a battery cell provided in some embodiments of the present application; Figure 18 Schematic cross-sectional views of negative electrode sheets of battery cells provided in other embodiments of the present application; Figure 19 Schematic cross-sectional views of the positive electrode sheets of battery cells provided in some other embodiments of the present application.

[0436] Reference Figure 13 as well as Figure 17-19In some embodiments, the electrode assembly 11 includes a positive electrode sheet 111, a negative electrode sheet 112, and a separator 113 located between the positive electrode sheet 111 and the negative electrode sheet 112. The positive electrode sheet 111 includes a positive electrode current collector 1111 and a positive electrode film layer 1112 arranged between 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 arranged on at least one side of the negative electrode current collector 1121. The negative electrode film layer 1122 includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0437] In the embodiment 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 may be provided on both sides of the negative electrode current collector 1121 .

[0438] Optionally, a negative electrode film layer 1122 is provided on two opposing surfaces of the negative electrode current collector 1121 along its thickness direction. The negative electrode film layers 1122 on both surfaces of the negative electrode current collector 1121 can use the same negative electrode active material or different negative electrode active materials; the thickness of the negative electrode film layers 1122 on both surfaces of the negative electrode current collector 1121 can be the same or different.

[0439] For example, the negative electrode current collector 1121 may be a metal foil or a composite current collector. Examples of metal foils include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0440] 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.

[0441] 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 disposed on either or both of the two opposite surfaces of the positive electrode current collector 1111 .

[0442] For example, the positive electrode current collector 1111 may be a metal foil or a composite current collector. Examples of metal foils include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal material of the metal layer may include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0443] Lithium-containing phosphates have high cycle stability. Using lithium-containing phosphates as positive electrode active materials can improve the cycle attenuation of the battery cell 10 caused by excessive temperature rise during rapid charging.

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

[0445] In some embodiments, the thickness of the negative electrode current collector 1121 is 4 μm to 6 μm. For example, 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 consisting of any two of the above values.

[0446] 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 1.36g / cm 3 .

[0447] For example, the battery cell 10 has a compaction density of the negative electrode film layer 1122 of 1.15 g / cm2 at 100% SOC. 3 , 1.18g / cm 3 , 1.20g / cm 3 , 1.22g / cm 3 , 1.25g / cm 3 , 1.28g / cm 3 , 1.3g / cm 3 , 1.32g / cm 3 , 1.35g / cm 3 , 1.36g / cm 3 Or a range consisting of any two of the above values.

[0448] For example, the compaction density of the negative electrode film layer of the battery cell 10 at 100% state of charge is known in the art. Specifically, the negative electrode sheet of the battery cell at 100% SOC is disassembled and the compaction density of the negative electrode film layer is measured. For example, a single-sided coated negative electrode sheet (if a double-sided coated negative electrode sheet, the negative electrode film layer on one side can be wiped off first) is punched into small discs with an area of S1. The discs are weighed and recorded as M1, and their thickness H1 is measured. The negative electrode film layer of the weighed negative electrode sheet is then wiped off, and the weight of the negative electrode current collector is weighed and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the negative electrode film layer = (weight of the negative electrode sheet M1 - weight of the negative electrode current collector M0) / S1. The thickness of the negative electrode film layer = thickness of the negative electrode sheet H1 - thickness of the negative electrode current collector H0. The compaction density of the negative electrode film layer = single-sided coating weight of the negative electrode film layer / thickness of the negative electrode film layer.

[0449] The compaction density of the negative electrode film layer 1122 is related to the expansion of the battery cell 10 at 100% state of charge. The compaction density of the negative electrode film layer 1122 is limited to 1.15 g / cm 3 to 1.36g / cm 3 , which can, to a certain extent, take into account both the energy density and the expansion pressure of the battery cell 10 , reduce the deformation of the battery cell 10 , and reduce the risk of failure in the connection between the battery cell 10 and the busbar component.

[0450] When the compaction density of the negative electrode film layer 1122 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and because the negative electrode active material in the negative electrode film layer 1122 is stacked relatively densely, the contact resistance between particles is small, which can reduce the resistance of the negative electrode sheet 112, thereby reducing heat generation, which is beneficial to improving the fast charging capability of the battery 2.

[0451] When the compaction density of the negative electrode film layer 1122 is within the above range, the fast charging capability of the battery cell 10 can be improved. A lower compaction density of the negative electrode film layer 1122 can increase the porosity of the negative electrode sheet 112, slow down the expansion of the negative electrode sheet, and reduce the expansion pressure of the battery cell 10.

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

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

[0454] The coating weight on one side of the negative electrode film layer 1122 is related to the expansion of the negative electrode film layer. The coating weight on one side of the negative electrode film layer 1122 is limited to 90 mg / 1540 mm 2 Up to 170mg / 1540mm 2 , which can, to a certain extent, take into account both the energy density and expansion pressure of the battery cell 10 , reduce the deformation of the battery cell 10 , reduce the risk of connection failure between the battery cell 10 and the busbar component, and improve reliability.

[0455] In addition, the coating weight of the negative electrode film layer 1122 on one side is limited to 90 mg / 1540 mm 2 Up to 170mg / 1540mm 2 It can also limit the heat generation 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.

[0456] In some embodiments, the coating weight of the negative electrode film layer 1122 on one side is 110 mg / 1540 mm 2 Up to 150mg / 1540mm 2 , in order to further take into account the energy density and expansion pressure of the battery cell 10.

[0457] 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 may be 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%.

[0458] The porosity of the negative electrode sheet can be defined as the percentage of the pore volume within the negative electrode sheet to the total volume of the negative electrode sheet. For example, when the battery cell is at a 0% state of charge, a double-sided coated negative electrode sheet is taken and the porosity of the negative electrode sheet is measured using an AccuPyc II 1340 density meter in accordance with the national standard GB / T 24586-2009.

[0459] In the embodiment of the present application, the porosity of the negative electrode sheet 112 is greater than or equal to 27%, which provides space for impurities generated by side reactions in the negative electrode sheet 112, slowing the expansion of the negative electrode sheet 112, reducing the expansion pressure of the battery cell 10, reducing deformation of the battery cell 10, improving the cycle performance of the battery cell 10, and enhancing 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 also take into account the energy density of the battery cell 10.

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

[0461] When the graphitization degree of the graphite particles is within the above range, the graphite particles have excellent electrical conductivity, 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 .

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

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

[0464] In some embodiments, the mass content of silicon in the silicon-based material in the negative electrode active material is 0.3% to 10%, optionally 1% to 6%. For example, the mass content of silicon 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 consisting of any two of the above values.

[0465] Introducing silicon-based materials into the negative electrode sheet 112 can both increase capacity and increase the expansion of the negative electrode sheet 112. Therefore, limiting the mass content of silicon 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 deformation of the battery cell 10, and improve the cycle performance and fast charging capability of the battery cell 10.

[0466] The qualitative and quantitative properties of each substance or element in this application can be detected using appropriate equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and international detection standards, domestic and international enterprise standards, etc., and those skilled in the art can also adapt certain detection steps / instrument parameters, etc. from the perspective of detection accuracy to obtain more accurate detection results. A single detection method can be used for qualitative or quantitative determination, or several detection methods can be used in combination for qualitative or quantitative determination.

[0467] For example, silicon-based materials can be subjected to X-ray powder diffraction testing and qualitative analysis on negative electrode sheets or negative electrode active materials in combination with JIS / K0131-1996 General Rules for X-ray Diffraction Analysis Methods.

[0468] In some embodiments, the silicon-based material may include at least one of elemental silicon, silicon oxide, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy material.

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

[0470] In some embodiments, the negative electrode active material may include at least one of a tin-based material and lithium titanate in addition to a carbon-based material and an optional silicon-based material. The tin-based material may include at least one of elemental tin, tin oxide, and a tin alloy.

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

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

[0473] When the negative electrode film layer 1122 comprises at least two 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 may be located in one of the at least two film layers, or in at least two of the at least two film layers. The negative electrode film layer 1122 may include two film layers, three film layers, four film layers, or even more film layers.

[0474] In some embodiments, the negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222, wherein 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, wherein the first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and a silicon-based material.

[0475] The interface between the first negative electrode film layer 11221 and the second negative electrode film layer 11222 may be regular or irregular; optionally, it may be irregular.

[0476] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be set differently, so as to take into account the expansion and capacity of the negative electrode film layer 1122 to a certain extent; the double-layer coating can construct the pore difference of the negative electrode film layer 1122, reduce the tortuosity of ion transmission, reduce side reactions, and improve the fast charging performance of the battery cell 10.

[0477] Artificial graphite can have a smaller volume average particle size Dv50, which can shorten the solid-phase transmission path of lithium ions and improve fast charging performance. On the other hand, the material is not easy to agglomerate during the preparation process, which can improve the stability of the material.

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

[0479] 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 4:6 to 6:4.

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

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

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

[0483] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material. Further optionally, the volume average particle size Dv50 of the first negative electrode active material is less than the volume average particle size Dv50 of the second negative electrode active material.

[0484] The difference in particle size between the first negative electrode active material and the second negative electrode active material can improve the rapid charging performance of the battery cell 10. During rapid charging, the overpotential of the first negative electrode film layer 11221 is generally high, and the bottleneck of rapid charging lies primarily in the first negative electrode film layer 11221. However, in the embodiment 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 rapid charging performance, and alleviate the problem of ion precipitation on the surface of the negative electrode sheet 112. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer 11222. During charging, the pores can absorb expansion, reducing the amount of expansion of the negative electrode film layer 1122 and improving the reliability of the battery cell 10 during rapid charging.

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

[0486] The volume average particle size Dv50 of the first negative electrode active material is set to 7.8μm-14.3μm. 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 easy to agglomerate during the preparation process, which can improve the stability of the material; on the other hand, the first negative electrode active material in the above volume average particle size range can be combined with the second negative electrode active material, which is conducive 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.

[0487] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. The detection can be carried out using equipment and methods known in the art. For example, the negative electrode active material is used as a sample, and the Dv50 and Dv10 of the particles are tested using a Mastersizer 2000E laser particle size analyzer in accordance with the test standard GB / T 19077-2016.

[0488] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm, and optionally 9.5-14.6 μm.

[0489] Illustratively, 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 consisting of any two of the above values.

[0490] 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 more abundant, which is beneficial to improving the fast charging capability of the battery cell 10 and reducing the expansion of the negative electrode film layer 1122 during charging.

[0491] 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, optionally 7.8 μm to 11.3 μm. Optionally, the first negative electrode active material includes artificial graphite.

[0492] 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 optionally 9.5 μm to 14.6 μm. Optionally, the second negative electrode active material includes natural graphite.

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

[0494] The specific surface area of a material is well known in the art and can be tested using equipment and methods well known in the art. For example, according to the test standard GB / T 19587-2017, the negative electrode active material is used as a sample and the specific surface area is tested using a Tri-Star 3020 specific surface area pore size analyzer produced by Micromeritics, USA.

[0495] The specific surface area of the negative electrode active material is limited to be greater than or equal to 0.5 m 2 / g, can improve the ability of the battery cell 10 to quickly charge; the specific surface area of the negative electrode active material is limited to less than or equal to 3m 2 / g, which can reduce the side reactions of the battery cell 10 during storage, slow down the expansion of the negative electrode sheet, and reduce the expansion pressure.

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

[0497] In some embodiments, the olivine-structured lithium-containing phosphate or its modified material can be the olivine-structured lithium-containing phosphate, or a material obtained by coating and modifying the olivine-structured lithium-containing phosphate. For example, the olivine-structured lithium-containing phosphate includes phosphate particles and an ion-conducting layer, the ion-conducting layer being coated on the surface of the phosphate particles, and the ion-conducting layer containing one or more elements selected from the group consisting of C, Fe, Ti, Zr, Hf, Ge, and Sn.

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

[0499] Optionally, the mass proportion of the olivine-structured lithium-containing phosphate or its modified material in the positive electrode active material is 100%.

[0500] In some embodiments, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80g / cm 3 ; Optional 2.55g / cm 3 -2.70g / cm 3 For example, when the battery cell 10 is at 100% state of charge (SOC), the compaction density of the positive electrode film layer 1112 is 2.50 g / cm 3 , 2.52g / cm 3 , 2.55g / cm 3 , 2.56g / cm 3 , 2.57g / cm 3 , 2.58g / cm3 , 2.60g / cm 3 , 2.62g / cm 3 , 2.65g / cm 3 , 2.68g / cm 3 , 2.30g / cm 3 , 2.32g / cm 3 , 2.75g / cm 3 , 2.78g / cm 3 , 2.80g / cm 3 Or a range consisting of any two of the above values.

[0501] When the compaction density of the positive electrode film layer 1112 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and because the positive electrode active materials in the positive electrode film layer 1112 are stacked relatively densely, the contact resistance between particles is small, which can further reduce the resistance of the positive electrode sheet 111, thereby reducing heat generation under fast charging.

[0502] In the embodiments of the present application, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is as known in the art. Specifically, the positive electrode sheet 111 is disassembled from the battery cell 10 at 100% SOC, and the compaction density of the positive electrode film layer 1112 is measured. For example, the compaction density of the positive electrode film layer 1112 can be tested using the same method as the compaction density of the negative electrode film layer 1122.

[0503] In some embodiments, the coating weight of the positive electrode film layer 1112 on one side is 200 mg / 1540 mm 2 -370mg / 1540 / mm 2 ; Optional: 240mg / 1540mm 2 Up to 330mg / 1540mm 2 For example, the coating weight of the positive electrode film layer 1112 on one side is 200 mg / 1540.25 mm 2 、210mg / 1540.25mm 2 、220mg / 1540.25mm 2 、230mg / 1540.25mm 2 、240mg / 1540.25mm 2 、250mg / 1540.25mm 2 、260mg / 1540.25mm 2 、270mg / 1540.25mm 2 、280mg / 1540.25mm 2 、290mg / 1540.25mm 2、300mg / 1540.25mm 2 、310mg / 1540.25mm 2 、320mg / 1540.25mm 2 、330mg / 1540.25mm 2 、340mg / 1540.25mm 2 、350mg / 1540.25mm 2 、360mg / 1540.25mm 2 、370mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0504] In the embodiment of the present application, the single-sided coating weight of the positive electrode film layer 1112 has a meaning well known in the art and can be detected using equipment and methods well known in the art, and its detection method is the same as the single-sided coating weight test method of the negative electrode film layer 1122 mentioned above.

[0505] The single-side coating weight of the positive electrode film layer 1112 is set at 200 mg / 1540 mm 2 -370mg / 1540 / mm 2 , which can limit the heat generation per unit area of the positive electrode sheet 111 and can improve both the energy density and the charge rate performance of the battery cell 10 .

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

[0507] In the embodiment of the present application, the porosity of the positive electrode sheet 111 is well known in the art and can be detected using equipment and methods well known in the art, such as the porosity testing method of the negative electrode sheet 112 .

[0508] The porosity of the positive electrode sheet 111 is greater than or equal to 25%, which provides space for impurities generated by side reactions in the positive electrode sheet 111, reduces the expansion pressure of the battery cell, reduces deformation of the battery cell 10, and improves the cycle performance of the battery cell 10. The porosity of the positive electrode sheet 111 is less than or equal to 32%, which can take into account the energy density of the battery cell 10 to a certain extent.

[0509] In some embodiments, the thickness of the positive electrode sheet 111 may be 0.13 mm-0.2 mm. For example, the thickness of the positive electrode sheet 111 may 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 consisting of any two of the above values.

[0510] In the embodiment of the present application, the thickness of the positive electrode sheet 111 has a well-known meaning in the art and can be detected using equipment and methods well-known in the art, for example, using a micrometer to measure the thickness of the positive electrode sheet 111.

[0511] 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.

[0512] In some embodiments, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film 1112 is 0.05 to 0.3. For example, in the embodiment of the present application, the thickness of the positive electrode film 1112 is the thickness of the positive electrode film 1112 located on one side of the positive electrode current collector 1111.

[0513] Illustratively, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, or a range consisting of any two of the above values.

[0514] Limiting the thickness ratio of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to greater than or equal to 0.05 can improve the current flow capacity of the positive electrode 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 electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to 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 electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is limited to 0.05 to 0.3, which can, to a certain extent, balance the fast charging capability and energy density of the battery cell 10.

[0515] The thickness of the positive electrode film layer and the thickness of the positive electrode current collector have well-known meanings in the art and can be detected using equipment and methods well-known in the art. For example, the thickness of the positive electrode sheet is measured using a micrometer, 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.

[0516] In some embodiments, the thickness of the positive electrode current collector 1111 is 10 μm to 15 μm, optionally 12 μm to 15 μm. For example, the thickness of the positive electrode current collector 1111 is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, or a range consisting of any two of the foregoing values. When the thickness of the positive electrode current collector 1111 is within the above range, the positive electrode current collector 1111 has excellent current flow capacity and can enable the battery cell 10 to have a higher energy density.

[0517] 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.

[0518] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1 μm≤Dv50≤2 μm, and 0.4 μm≤Dv10≤0.7 μm.

[0519] 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.

[0520] For example, the Dv10 of the positive electrode active material may be 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, or a range consisting of any two of the above values.

[0521] The particle size of the positive electrode active material is relatively small, the lithium ion deintercalation path in the positive electrode active material is short, and the heat generation is less; and the particle size of the above-mentioned 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.

[0522] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. The detection can be carried out using equipment and methods known in the art. For example, the positive electrode active material is used as a sample, and the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer according to the test standard GB / T 19077-2016.

[0523] In some embodiments, the battery cell 10 includes an electrolyte contained within a housing 12. During the charge and discharge process of the battery cell 10, active ions are intercalated and released back and forth between the positive electrode sheet 111 and the negative electrode sheet 112, and the electrolyte serves to conduct the active ions between the positive electrode sheet 111 and the negative electrode sheet 112.

[0524] In some embodiments, the conductivity of the electrolyte at room temperature (e.g., 25° C.) is 13 mS / cm to 20 mS / cm, or optionally 15 mS / cm to 20 mS / cm. For example, 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 consisting of any two of the foregoing values.

[0525] When the conductivity of the electrolyte is within the above range, the migration rate of ions in the electrolyte is high, thereby further reducing the internal resistance of the battery cell 10 , reducing heat generation, and improving the fast charging performance of the battery cell 10 .

[0526] The conductivity of the electrolyte is ionic conductivity, which can be tested using equipment and methods known in the art, for example, by referring to the industry standard HG-T 4067-2015.

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

[0528] Illustratively, 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 consisting of any two of the foregoing values.

[0529] When the density ρ of the electrolyte is within the above range, the migration rate of lithium ions in the electrolyte is high, which can further reduce the internal resistance of the battery cell 10, thereby reducing heat generation and improving the fast charging performance of the battery cell 10.

[0530] In the embodiments of the present application, the density of the electrolyte has a well-known meaning in the art and can be tested using equipment and methods well-known in the art, for example, by referring to GB / T 2013-2010.

[0531] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of a carbonate solvent and a carboxylate solvent.

[0532] 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%. For example, 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 consisting 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 low, which is conducive to the migration of lithium ions.

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

[0534] In some embodiments, the carboxylate comprises R1-COO-R2, where R1 and R2 independently comprise an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms. The above-mentioned chain carboxylate solvent has high electrical conductivity, which is beneficial for improving the fast charging capability of the battery cell 10.

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

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

[0537] The carbonate solvent and the chain carboxylate solvent are used in combination to improve the conductivity of the electrolyte, which is beneficial to the migration of lithium ions.

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

[0539] Illustratively, 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%.

[0540] The addition of organic solvents can increase the conductivity of the electrolyte and reduce its viscosity, thereby improving the fast charging performance of the battery.

[0541] In some embodiments, the electrolyte includes a lithium salt. The lithium salt includes one or more of a fluorinated sulfonyl imide salt and lithium hexafluorophosphate (LiPF6). These lithium salts are easily dissociated, facilitating rapid lithium ion migration. Furthermore, the electrolyte system is relatively stable and resistant to decomposition, which can enhance the cycling performance of the battery cells.

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

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

[0544] Optionally, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration in lithium hexafluorophosphate (LiPF6) is (2 to 5):10. Exemplarily, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration in lithium hexafluorophosphate (LiPF6) is 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10, 5:10, or a range consisting of any two of the foregoing values.

[0545] According to some embodiments of the present application, the present application further provides an electrical device, comprising the battery 2 of any of the above embodiments, the battery 2 being used to provide power to the electrical device. The electrical device may be any of the aforementioned devices or systems using the battery 2.

[0546] Reference Figures 2 to 5 An embodiment of the present application provides a battery 2, which includes a box body 20, multiple battery cell groups 100 and multiple heat exchange components 30, and the multiple battery cell groups 100 and the multiple heat exchange components 30 are accommodated in the box body 20.

[0547] 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 arranged opposite to each other 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 on the upper side of the second box wall 22. The first box wall 21, the second box wall 22 and the frame 23 enclose a storage space.

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

[0549] A heat exchange element 30 is provided between every two battery cell groups 100 .

[0550] The battery cell 10 includes a shell 12, an electrode assembly 11 and a pressure relief mechanism 15. The shell 12 includes a first end wall 12a, a second end wall 12b and a side wall 12c. The first end wall 12a is located on the side of the electrode assembly 11 facing the second box wall 22, and the first end wall 12a is spaced apart 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 adhered to the first box wall 21.

[0551] The sidewalls 12c include two first sidewalls 12d and two second sidewalls 12e. The two first sidewalls 12d are arranged opposite each other along the thickness direction X of the battery cell 10. The two second sidewalls 12e are arranged opposite each other along a first direction Y perpendicular to the thickness direction X. Each second sidewall 12e connects two first sidewalls 12d. One first sidewall 12d of the battery cell 10 is connected to the heat exchange element 30 to exchange heat.

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

[0553] Under room temperature conditions, the charging time for the battery cell 10 from 10% SOC to 80% SOC may be 5 minutes to 10.5 minutes.

[0554] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0555] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized in that: include: The box body includes a first box wall; A plurality of battery cells are housed in the box and located on the lower side of the first box wall. The battery cells include a shell, an electrode assembly, and a pressure relief mechanism. The shell is fixed to the first box wall. The electrode assembly is housed in the shell. The shell includes a first end wall. The first end wall is located on a side of the electrode assembly away from the first box wall. The pressure relief mechanism is provided on the first end wall. Wherein, at room temperature, the charging time of the battery cell from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes; a plurality of busbars, the plurality of busbars electrically connecting the plurality of battery cells; The plurality of busbar members include at least one first busbar member 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 along a thickness direction of the battery cells.

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

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

4. The battery according to claim 3, characterized in that The housing further includes a second end wall and a side wall, the first end wall is disposed opposite to the second end wall, the side wall connects the first end wall and the second end wall and surrounds the electrode assembly, and the second end wall is fixed to the first box wall; The heat exchange element is arranged on the side wall.

5. The battery according to claim 4, characterized in that The side walls include two first side walls and two second side walls, the two first side walls are arranged opposite to each other along the thickness direction of the battery cell, the two second side walls are arranged opposite to each other along a first direction perpendicular to the thickness direction, and each second side wall connects the two first side walls; At least one of the first side walls of the battery cell is connected to the heat exchange element.

6. The battery according to claim 5, characterized in that The electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed between the positive electrode current collectors, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes an olivine-structured lithium-containing phosphate; One of the first side walls of the battery cell is connected to the heat exchange element.

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

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

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

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

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

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

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

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

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

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

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

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

19. The battery according to claim 13, characterized in that In the width direction of the first end wall, the size of the first end wall is W1 mm, and the size of the portion of the first electrode terminal located outside the first end wall is W2 mm; W2 and W1 satisfy: 0.4≤W2 / W1≤1.

20. The battery according to claim 1, characterized in that The box body further includes a second box wall, which is arranged on the lower side of the battery cell and opposite to the first box wall.

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

22. The battery according to claim 1, characterized in that The utility model further comprises a support member, wherein the support member is arranged on the lower side of the first end wall and is used for supporting the first end wall.

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

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

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

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

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

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

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

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

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

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

33. The battery according to claim 1, 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.

34. The battery according to claim 33, 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. The second buffer portion connects the first stacking portion and the second stacking portion.

35. The battery according to claim 1, characterized in that The box body further includes a plurality of limiting beams connected to the first box wall, the plurality of limiting beams are arranged at intervals along the thickness direction of the battery cells, and a plurality of the battery cells are arranged between adjacent limiting 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%.

36. The battery according to claim 1, characterized in that The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged between the positive electrode current collectors. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes an olivine-structured lithium-containing phosphate. 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.

37. The battery according to claim 36, characterized in that The single-side coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 Up to 170mg / 1540mm 2 .

38. The battery according to claim 37, characterized in that The single-side coating weight of the negative electrode film layer is 110 mg / 1540 mm 2 Up to 150mg / 1540mm 2 .

39. The battery according to claim 36, 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 to 1.36g / cm 3 .

40. The battery according to claim 39, characterized in that The compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.25 g / cm 3 to 1.36g / cm 3 .

41. The battery according to claim 36, characterized in that The porosity of the negative electrode sheet is 27%-40%.

42. The battery according to claim 36, characterized in that The carbon-based material includes at least one of artificial graphite and natural graphite.

43. The battery according to claim 36, characterized in that The negative electrode active material further comprises a silicon-based material, and the mass content of silicon in the silicon-based material is 0.3% to 10% in the negative electrode active material.

44. The battery according to claim 43, characterized in that The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% to 6%.

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

46. The battery according to claim 36, characterized in that The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the second negative electrode film layer is 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.

47. The battery according to claim 46, 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.

48. The battery according to claim 47, characterized in that The ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer is 4:6 to 6:

4.

49. The battery according to claim 46, 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.

50. The battery according to claim 46, characterized in that The volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material.

51. The battery according to claim 46, characterized in that The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm.

52. The battery according to claim 51, characterized in that The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-11.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5-14.6 μm.

53. The battery according to claim 36, characterized in that The specific surface area of the negative electrode active material is 0.5 m 2 / g-3m 2 / g.

54. The battery according to claim 53, characterized in that The specific surface area of the negative electrode active material is 0.6 m 2 / g-1.2m 2 / g.

55. The battery according to claim 36, characterized in that The chemical formula of the lithium-containing phosphate with olivine structure is LiFe 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

56. The battery according to claim 36, characterized in that The single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370mg / 1540 / mm 2 .

57. The battery according to claim 56, 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 .

58. The battery according to claim 36, 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 to 2.80g / cm 3 .

59. The battery according to claim 58, 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 .

60. The battery according to claim 36, characterized in that The porosity of the positive electrode sheet is 25%-32%.

61. The battery according to claim 36, characterized in that The thickness of the positive electrode sheet is 0.13mm-0.2mm.

62. The battery according to claim 36, 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.

63. The battery according to claim 36, characterized in that The volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm and 0.4µm≤Dv10≤0.7µm.

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

65. The battery according to claim 64, characterized in that The conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm.

66. The battery according to claim 64, 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.

67. The battery according to claim 66, characterized in that The carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

68. The battery according to claim 66, characterized in that The carboxylate comprises R1-COO-R2, wherein R1 and R2 independently comprise an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms.

69. The battery according to claim 64, 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.

70. The battery according to claim 64, characterized in that The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL≤ρ≤1.35 g / mL.

71. An electrical device, characterized in that: The battery according to any one of claims 1 to 70 is used to provide electrical energy.

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