Battery and electric device

Abstract

The invention provides a battery and an electric device. The battery includes a plurality of battery cells and a first bus member. The plurality of battery cells are arranged along the thickness direction of the battery cells, and each battery cell comprises a shell and an electrode assembly accommodated in the shell. And the expansion pressure intensity of the battery monomer in the thickness direction is 0.5 MPa to 2.4 MPa. The first confluence component is electrically connected with at least two battery monomers arranged along the thickness direction, and the first confluence component is of a multi-layer structure. The electrode assembly comprises a positive plate, a negative plate and an isolating membrane located between the positive plate and the negative plate, the positive plate comprises a positive current collector and a positive membrane layer arranged on at least one side of the positive current collector, the positive membrane layer comprises a positive active material, and the positive active material comprises lithium-containing phosphate of an olivine structure. The negative plate comprises a negative current collector and a negative film layer arranged on at least one side of the negative current collector, the negative film layer comprises a negative active material, and the negative active material comprises a carbon-based material.

Description

[0001] This application claims the priority of the international patent application PCT / CN2024 / 102665 titled "Battery and Electrical Appliance" filed on June 28, 2024, the entire content of which is incorporated herein by reference. Technical Field

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

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

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

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

[0006] In a first aspect, an embodiment of this application provides a battery, which includes a plurality of battery cells and a first busbar component. The plurality of battery cells are arranged along the thickness direction of the battery cell. The battery cell includes a housing and an electrode assembly accommodated in the housing. The expansion pressure of the battery cell in the thickness direction is 0.5 MPa - 2.4 MPa. The first busbar component is electrically connected to at least two battery cells arranged along the thickness direction, and the first busbar component is a multi-layer structure. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure. The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0007] The expansion pressure of the battery cell is related to the compactness of the electrode assembly. The embodiments of the present application can allow the battery cell to have an expansion pressure greater than or equal to 0.5 MPa in the thickness direction, thereby improving the compactness of the electrode assembly and increasing the energy density of the battery cell. The expansion pressure of the battery cell in the thickness direction is less than or equal to 2.4 MPa, which can limit the deformation of the electrode assembly during cycling, reduce the risk of wrinkling deformation of the separator of the electrode assembly and the risk of increased local spacing between the positive electrode sheet and the negative electrode sheet, reduce polarization, and improve the cycling performance of the battery cell. The first current collecting component has a multi-layer structure, and each layer structure of the first current collecting component can conduct current, so that the first current collecting component can have a relatively large current-carrying area, thereby reducing the heat generation of the first current collecting component and improving the fast charging ability and reliability of the battery.

[0008] On the premise that the current-carrying area meets the requirements, setting the first current collecting component as a multi-layer structure can reduce the thickness of each layer structure of the first current collecting component. During cycling, the battery cell expands, thereby stretching the layer structure of the first current collecting component connected to the battery cell. The layer structure of the first current collecting component has a small thickness and is easy to deform to adapt to the expansion deformation of the battery cell. Therefore, when the expansion pressure of the battery cell is 0.5 MPa - 2.4 MPa, the risk of the connection between the battery cell and the first current collecting component being torn is reduced, and the reliability of the battery is improved.

[0009] Adopting the first current collecting component with a multi-layer structure can adapt to the expansion of the battery cell and take into account the current-carrying capacity and deformability of the first current collecting component, thereby improving the reliability and fast charging ability of the battery.

[0010] In some embodiments, the first current collecting component includes a first current collecting layer and a second current collecting layer that are stacked and connected. The first current collecting layer is connected to at least two battery cells arranged in the thickness direction.

[0011] Both the first current collecting layer and the second current collecting layer can conduct current, so that the first current collecting component can have a relatively large current-carrying area, thereby reducing the heat generation of the first current collecting component and improving the fast charging ability and reliability of the battery. On the premise that the current-carrying area meets the requirements, setting the first current collecting component as a double-layer structure can reduce the requirement for the thickness of the first current collecting layer. During cycling, the battery cell expands, thereby stretching the first current collecting layer. The first current collecting layer has a small thickness and is easy to deform to adapt to the deformation of the battery cell, reducing the risk of the connection between the battery cell and the first current collecting layer being torn and improving the reliability of the battery.

[0012] In some embodiments, the battery cell includes electrode terminals disposed on the outer casing, and the electrode terminals are electrically connected to the electrode assembly. The portion of the first current collecting layer that does not overlap with the second current collecting layer is connected to the electrode terminals. The second current collecting layer can avoid the connection between the first current collecting layer and the electrode terminals, so as to reduce the influence of the second current collecting layer on the connection between the first current collecting layer and the electrode terminals when the battery cell expands, reduce the risk of the connection between the electrode terminals and the first current collecting layer being torn, and improve the reliability of the battery.

[0013] In some embodiments, the first current collecting layer is welded to the electrode terminals, and the welding area between the first current collecting layer and the electrode terminals is greater than or equal to 60 mm 2 . There is a large current-carrying area between the first current collecting layer and the electrode terminals, thereby reducing the heat generation at the welding point, reducing the temperature rise of the first current collecting layer during fast charging, and improving the fast charging ability of the battery.

[0014] In some embodiments, the first current collecting component includes at least one bending portion, and the bending portion connects the first current collecting layer and the second current collecting layer. The bending portion can connect the first current collecting layer and the second current collecting layer and transmit current between the first current collecting layer and the second current collecting layer, thereby improving the current-carrying capacity of the first current collecting component.

[0015] In some embodiments, the first current collecting layer includes a first current collecting portion, a second current collecting portion, and a first buffer portion. The first current collecting portion and the second current collecting portion are disposed along the thickness direction and are connected to different battery cells, and the first buffer portion connects the first current collecting portion and the second current collecting portion. At least one of the first current collecting portion and the second current collecting portion is connected to the bending portion. During the cycling of the battery cell, the battery cell expands and applies a tensile force to the first current collecting layer; the first buffer portion can release stress through deformation, thereby reducing the force on the connection between the first current collecting portion and the battery cell and the force on the connection between the second current collecting portion and the battery cell, and reducing the risk of the connection failure between the first current collecting layer and the battery cell.

[0016] In some embodiments, the bending portion and the first buffer portion are arranged to avoid each other. The bending portion is not directly connected to the first buffer portion, thereby reducing the influence of the bending portion on the deformation of the first buffer portion and reducing the difficulty of deforming the first buffer portion.

[0017] In some embodiments, the second current collecting layer includes a first stacked portion, a second stacked portion, and a second buffer portion. The first stacked portion is stacked with the first current collecting portion and connected by at least one bending portion, and the second stacked portion is stacked with the second current collecting portion and connected by at least one bending portion. The second buffer portion connects the first stacked portion and the second stacked portion. In the stacking direction of the first current collecting layer and the second current collecting layer, the second buffer portion and the first buffer portion at least partially overlap.

[0018] During the cycling of the battery cell, the battery cell expands and applies a tensile force to the first current collecting layer; both the first buffer portion and the second buffer portion can release stress through deformation, thereby reducing the risk of connection failure between the first current collecting layer and the battery cell. The second buffer portion overlaps at least partially with the first buffer portion, so that the deformation regions of the first buffer portion and the second buffer portion are close, thereby reducing the risk of interference between the first buffer portion and the second buffer portion and other parts during deformation.

[0019] In some embodiments, the second buffer portion and the first buffer portion are disposed in a fitting manner, which can save space and improve the current-carrying capacity.

[0020] In some embodiments, the battery further includes at least one second current collecting component. The second current collecting component has a single-layer structure and is connected to at least two battery cells. The thickness of the second current collecting component is greater than the thickness of the first current collecting layer and greater than the thickness of the second current collecting layer. In the battery, the expansion amounts of the battery cells at different positions may vary. For the battery cells with a smaller expansion amount, the second current collecting component with a single-layer structure can be used; compared with the first current collecting component, the second current collecting component has a simple structure, is easy to manufacture, and can save costs. The thickness of the second current collecting component is greater than the thicknesses of the first current collecting layer and the second current collecting layer, and its current-carrying capacity can meet the requirements.

[0021] In some embodiments, the sum of the thicknesses of the first current collecting layer and the second current collecting layer is equal to the thickness of the second current collecting component, which can reduce the difference in the current-carrying capacities between the first current collecting component and the second current collecting component and improve the current consistency.

[0022] In some embodiments, among the multiple battery cells, the outermost battery cell in the thickness direction is connected to the first current collecting component. During the charging process, the expansions of the multiple battery cells may be superimposed in the thickness direction, resulting in a relatively large displacement of the outermost battery cell in the thickness direction; using the first current collecting component with a multi-layer structure to connect the outermost battery cell can reduce the risk of connection failure between the first current collecting component and the battery cell.

[0023] In some embodiments, the thickness of the first current collecting layer is 1 mm - 2.5 mm, and can be optionally 1.2 mm - 1.8 mm. In the embodiments of the present application, the thickness of the first current collecting layer is selected according to the expansion pressure of the battery cell, which can balance the current-carrying capacity and the deformability of the first current collecting layer to a certain extent, thereby improving the fast charging ability and reliability of the battery.

[0024] In some embodiments, the thickness of the second current collecting layer is 1 mm - 2.5 mm, and can be optionally 1.2 mm - 1.8 mm.

[0025] In some embodiments, the volumetric energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the thickness of the first current collecting layer is less than or equal to 2.5 mm; alternatively, the volumetric energy density of the battery cell is 450 Wh / L - 480 Wh / L, and the thickness of the first current collecting layer is less than or equal to 2.2 mm.

[0026] The expansion of the battery cell is related to its volumetric energy density. In this application, the thickness of the first current collecting layer is designed according to the volumetric energy density of the battery cell, so as to balance the current-carrying capacity and deformability of the first current collecting layer to a certain extent, thereby improving the fast charging ability and reliability of the battery.

[0027] In some embodiments, the negative electrode active material further includes a silicon-based material. The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% - 6%; the thickness of the first current collecting layer is 1.2 mm - 2.2 mm, and the thickness of the second current collecting layer is 1.2 mm - 2.2 mm.

[0028] By introducing the silicon-based material, the capacity of the negative electrode sheet can be improved, and the energy density of the battery cell can be increased. Introducing the silicon-based material will also increase the expansion of the negative electrode sheet during cycling. Designing the thicknesses of the first current collecting layer and the second current collecting layer in combination with the content of silicon element can reduce the risk of connection failure between the first current collecting layer and the battery cell caused by introducing the silicon-based material, and meet the requirements for the current-carrying capacity of the first current collecting component.

[0029] In some embodiments, the first current collecting layer includes a first current collecting portion, a second current collecting portion, and a first buffer portion connecting the first current collecting portion and the second current collecting portion. The first current collecting portion and the second current collecting portion are arranged along the thickness direction and are connected to different battery cells. In the stacking direction of the first current collecting layer and the second current collecting layer, the first buffer portion protrudes from the first current collecting portion and the second current collecting portion. The first current collecting layer is provided with a concave portion at a position corresponding to the first buffer portion. By providing the concave portion, the strength of the first buffer portion can be reduced, facilitating the deformation of the first buffer portion when the battery cell expands.

[0030] In some embodiments, the volumetric energy density of the battery cell is 390 Wh / L - 450 Wh / L, and the depth of the concave portion is 1.2 mm - 2.5 mm; alternatively, the volumetric energy density of the battery cell is 450 Wh / L - 480 Wh / L, and the depth of the concave portion is 1 mm - 2.2 mm.

[0031] The expansion of the battery cell is related to its volumetric energy density. In this application, the depth of the concave portion is designed according to the volumetric energy density of the battery cell, so as to balance the current-carrying capacity and deformability of the first buffer portion to a certain extent, thereby improving the fast charging ability and reliability of the battery.

[0032] In some embodiments, the electrode assembly includes two first surfaces and two second surfaces. The two first surfaces are disposed opposite to each other in the thickness direction, the two second surfaces are disposed opposite to each other in a direction perpendicular to the thickness direction, and the second surfaces connect the two first surfaces. The area of the first surface is larger than the area of the second surface.

[0033] In some embodiments, the expansion pressure of the battery cell in the thickness direction is 1.5 MPa - 2.0 MPa. Limiting the expansion pressure of the battery cell in the thickness direction within the above range can reduce the pulling force of the battery cell on the first current collecting component during the cycling process of the battery cell, reduce the risk of connection failure between the battery cell and the first current collecting component, and improve the reliability of the battery.

[0034] In some embodiments, the single-sided coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , and can be optionally 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 . The single-sided coating weight of the negative electrode film layer is related to the expansion of the negative electrode film layer. Limiting the single-sided coating weight of the negative electrode film layer within the above range can balance the energy density and expansion pressure of the battery cell to a certain extent, reduce the deformation of the battery cell, and reduce the risk of connection failure between the battery cell and the first current collecting component.

[0035] In some embodiments, the compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 , and can be optionally 1.25 g / cm 3 to 1.36 g / cm 3 . The compaction density of the negative electrode film layer is related to the expansion of the battery cell at 100% state of charge. Limiting the compaction density of the negative electrode film layer to 1.15 g / cm 3 to 1.36 g / cm 3 can balance the energy density and expansion pressure of the battery cell to a certain extent, reduce the deformation of the battery cell, and reduce the risk of connection failure between the battery cell and the first current collecting component.

[0036] When the compaction density of the negative electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell; and since the negative electrode active materials in the negative electrode film layer are stacked relatively tightly and the contact resistance between particles is small, the resistance of the negative electrode sheet can be reduced, thereby reducing heat generation.

[0037] When the compaction density of the negative electrode film layer is within the above range, the fast charging ability of the battery cell can be improved. When the compaction density of the negative electrode film layer is small, the porosity of the negative electrode sheet can be increased, the expansion of the negative electrode sheet can be slowed down, and the expansion pressure of the battery cell can be reduced.

[0038] In some embodiments, the porosity of the negative electrode sheet is 27% - 40%. The porosity of the negative electrode sheet being greater than or equal to 27% can provide space for impurities generated by side reactions in the negative electrode sheet, slow down the swelling of the negative electrode sheet, reduce the swelling pressure of the battery cell, reduce the deformation of the battery cell, improve the cycling performance of the battery cell, and reduce the risk of connection failure between the battery cell and the first current collecting component. The porosity of the negative electrode sheet being less than or equal to 40% can take into account the energy density of the battery cell.

[0039] 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 the heat generation of the negative electrode sheet during charging and improve the fast charging performance of the battery cell.

[0040] In some embodiments, the negative electrode active material further includes a silicon-based material, and the mass content of silicon element in the silicon-based material in the negative electrode active material is 0.3% to 10%, and can be selected as 1% to 6%.

[0041] Introducing a silicon-based material into the negative electrode sheet can not only increase the capacity but also increase the swelling of the negative electrode sheet. Therefore, limiting the mass content of silicon element in the negative electrode active material within the above range can, to a certain extent, take into account the energy density and swelling of the battery cell, reduce the deformation of the battery cell, improve the cycling performance of the battery cell, and reduce the risk of connection failure between the battery cell and the first current collecting component.

[0042] In some embodiments, the silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

[0043] In some embodiments, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, and the second negative electrode film layer is disposed between the first negative electrode film layer and the negative electrode current collector. The negative electrode active material includes a first negative electrode active material disposed in the first negative electrode film layer and a second negative electrode active material disposed in the second negative electrode film layer. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials. The first negative electrode film layer and the second negative electrode film layer can be differentially set, so as to take into account the swelling and capacity of the negative electrode film layer to a certain extent; double-layer coating can construct the pore difference of the negative electrode film layer, reduce the ion transport tortuosity, reduce side reactions, and improve the fast charging performance of the battery cell.

[0044] In some embodiments, the ratio of the thickness of the first negative electrode film layer to the thickness of the second negative electrode film layer is 3:7 to 7:3, and can be selected as 4:6 to 6:4. By adjusting the thickness ratio of the first negative electrode film layer and the second negative electrode film layer, the gradient pore difference between the upper and lower layers can be further increased, the lithium ion transport tortuosity can be reduced, and the fast charging ability of the battery cell can be improved. In some embodiments, the thickness of the first negative electrode film layer is less than or equal to the thickness of the second negative electrode film layer, which can further improve the fast charging ability of the battery cell.

[0045] 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.

[0046] There are differences in the particle sizes of the first negative electrode active material and the second negative electrode active material, which can improve the fast charging performance of the battery cell; during fast charging, the overpotential of the first negative electrode film layer is usually relatively high, and the bottleneck of fast charging mainly lies in the first negative electrode film layer. In the embodiments of the present application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transport path of ions, improve the fast charging performance, and can improve the problem of ion precipitation on the surface layer of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer. During charging, the pores can absorb expansion, reduce the expansion amount of the negative electrode film layer, reduce the force exerted by the battery cell on the first current collecting component, and reduce the risk of connection failure between the battery cell and the first current collecting component.

[0047] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm - 14.3 μm, and can be optionally 7.8 μm - 11.3 μm.

[0048] When the volume average particle size Dv50 of the first negative electrode active material is set within the above range, on the one hand, it can shorten the solid-phase transport path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material; on the third hand, the first negative electrode active material within the above volume average particle size range can cooperate with the second negative electrode active material, which is beneficial to constructing the gradient pore difference between the first negative electrode film layer and the second negative electrode film layer, reducing the tortuosity of lithium ion transport, and improving the fast charging performance of the battery cell.

[0049] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, and can be optionally 9.5 μm - 14.6 μm. Setting the volume average particle size Dv of the second negative electrode active material within the above range can make the pores of the second negative electrode film layer more abundant, which is beneficial to improving the fast charging ability of the battery cell and reducing the expansion of the negative electrode film layer during charging.

[0050] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g, and can be optionally 0.6 m 2 / g - 1.2 m 2 / g. Limiting the specific surface area of the negative electrode active material to be greater than or equal to 0.5 m2 / g can improve the ability of a single battery cell to be quickly charged; limiting the specific surface area of the negative electrode active material to be less than or equal to 3 m 2 / g can reduce side reactions during the storage of a single battery cell and reduce the swelling pressure.

[0051] In some embodiments, the single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 ; optionally 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2 . When the single-sided coating weight of the positive electrode film layer is set within the above range, the heat generation per unit area of the positive electrode sheet can be limited, and the energy density and charging rate performance of a single battery cell can be taken into account.

[0052] In some embodiments, the compaction density of the positive electrode film layer at 100% SOC of the single battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 ; optionally 2.55 g / cm 3 -2.70 g / cm 3 . When the compaction density of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of a single battery cell; and since the positive electrode active materials in the positive electrode film layer are stacked relatively tightly and the contact resistance between particles is small, the resistance of the positive electrode sheet can be further reduced, thereby reducing heat generation during fast charging.

[0053] In some embodiments, the porosity of the positive electrode sheet is 25% - 32%. When the porosity of the positive electrode sheet is greater than or equal to 25%, it can provide space for impurities generated by side reactions in the positive electrode sheet, reduce the swelling pressure of a single battery cell, reduce the deformation of the single battery cell, improve the cycle performance of the single battery cell, and reduce the risk of connection failure between the single battery cell and the busbar components. When the porosity of the positive electrode sheet is less than or equal to 32%, the energy density of a single battery cell can be taken into account to a certain extent.

[0054] In some embodiments, the thickness of the positive electrode sheet is 0.13 mm - 0.2 mm. Using a positive electrode sheet with a smaller thickness can shorten the ion migration path, increase the ion migration rate, reduce the heat generation of a single battery cell, and improve the fast charging performance of a single battery cell.

[0055] In some embodiments, the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer is 0.05 - 0.3. Limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be greater than or equal to 0.05 can improve the current-carrying capacity of the positive current collector, reduce the temperature rise of the positive electrode sheet, and improve the fast charging performance of the battery cell; limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer to be less than or equal to 0.3 can reduce the loss of the capacity of the positive electrode sheet. By limiting the ratio of the thickness of the positive current collector to the thickness of the positive electrode film layer within the above range in the embodiments of the present application, the fast charging ability and energy density of the battery cell can be balanced to a certain extent.

[0056] In some embodiments, the volume average particle size of the positive active material satisfies 1 µm ≤ Dv50 ≤ 2 µm, and 0.4 µm ≤ Dv10 ≤ 0.7 µm. The particle size of the positive active material is relatively small, the lithium deintercalation / lithiation path of lithium ions in the positive active material is short, and the heat generation is less; moreover, the particle size of the above positive active material is not too small, which can reduce agglomeration during the processing and preparation process, making the performance of the positive active material stable.

[0057] In some embodiments, the battery cell includes an electrolyte accommodated in a housing.

[0058] In some embodiments, the conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm. When the conductivity of the electrolyte is within the above range, the migration rate of ions in the electrolyte is relatively high, thereby further reducing the internal resistance of the battery cell, reducing heat generation, and improving the fast charging performance of the battery cell.

[0059] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents. The combination of organic solvents can improve the conductivity of the electrolyte and reduce the viscosity, thereby improving the fast charging performance of the battery.

[0060] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0061] In some embodiments, the carboxylate includes R 1 -COO-R 2 ,R 1 and R 2 each independently includes an alkyl group having 1 - 5 carbon atoms or a halogenated alkyl group having 1 - 5 carbon atoms. The above chain-like carboxylate solvents have relatively high conductivity, which is beneficial to improving the fast charging ability of the battery cell.

[0062] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF 6, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is from 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is from 0.5 mol / L to 1.0 mol / L.

[0063] In some embodiments, the density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL. When the density ρ of the electrolyte is within the above range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.

[0064] In some embodiments, the size of the electrode assembly in the thickness direction is T, the thickness of a single-layer negative electrode sheet is T1, and the number of layers of the negative electrode sheets stacked in the thickness direction is N; T, T1, and N satisfy: 0.3 ≤ (N × T1) / T ≤ 0.5.

[0065] During the cycling of the battery cell, the thickness of the negative electrode sheet increases due to irreversible side reactions, thereby causing the battery cell to expand; limiting (N × T1) / T within the above range can reduce the expansion of the battery cell and reduce the risk of connection failure between the battery cell and the current collecting component.

[0066] In some embodiments, the charging time of the battery cell from 10% SOC to 80% SOC is from 5 minutes to 10.5 minutes.

[0067] In a second aspect, embodiments of the present application provide an electrical device, which includes the battery provided in any one of the embodiments of the first aspect, and the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on the drawings without creative efforts.

[0069] Figure 1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application; Figure 2 is a schematic diagram of a battery provided in some embodiments of the present application; Figure 3 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application; Figure 4 is a schematic diagram of a battery provided in some embodiments of the present application; Figure 5 is Figure 4Enlarged schematic view at the circular frame; Figure 6 is Figure 5 Schematic structural view of the first current collecting component shown; Figure 7 Schematic connection view of a battery cell and a first current collecting component provided in some embodiments of the present application; Figure 8 is Figure 3 Schematic view of the electrode assembly described; Figure 9 is Figure 8 Cross-sectional schematic view of the electrode assembly shown; Figure 10 Cross-sectional schematic view of the negative electrode sheet of a battery cell provided in some embodiments of the present application; Figure 11 Cross-sectional schematic view of the positive electrode sheet of a battery cell provided in some embodiments of the present application; Figure 12 Cross-sectional schematic view of the negative electrode sheet of a battery cell provided in some other embodiments of the present application; Figure 13 Top view schematic of a battery provided in some other embodiments of the present application; Figure 14 is Figure 13 Enlarged schematic view at the square frame; Figure 15 is Figure 14 Schematic structural view of the second current collecting component in.

[0070] Explanation of reference numerals is as follows 1, vehicle; 2, battery; 3, controller; 4, motor; 10, battery cell; 100, battery cell column; 10a, large surface; 10b, narrow surface; 11, electrode assembly; 111, positive electrode sheet; 1111, positive current collector; 1112, positive electrode film layer; 112, negative electrode sheet; 1121, negative current collector; 1122, negative electrode film layer; 11221, first negative electrode film layer; 11222, second negative electrode film layer; 112a, flat layer; 113, separator; 11a, main body; 11b, positive electrode tab; 11c, negative electrode tab; 11d, first surface; 11e, second surface; 11f, third surface; 12, outer shell; 121, housing; 122, end cap; 13, electrode terminal; 20, box body; 21, limiting beam; 22, frame body; 23, support beam; 24, bearing plate; 30. Confluence component; 30a. First confluence component; 30b. Second confluence component; 30c. Third confluence component; 31. First confluence layer; 311. First confluence part; 312. Second confluence part; 313. First buffer part; 314. Concave part; 32. Second confluence layer; 321. First stacked part; 322. Second stacked part; 323. Second buffer part; 33. Bent part; X. Thickness direction; Y. Width direction; Z. Height direction. Detailed implementation manners

[0071] Hereinafter, for the purpose of making the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0072] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of the present application or the above drawings are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship.

[0073] Referring to "embodiments" in the present application means that specific features, structures or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0074] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "attached" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0075] In this application, the term "and / or" is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in this application, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0076] In the embodiments of this application, the same reference numerals represent the same components. And for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width, etc. of various components shown in the drawings in the embodiments of this application, as well as the overall thickness, length, width, etc. of the integrated device, are only for illustrative purposes and should not constitute any limitation to this application.

[0077] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0078] The term "a plurality of" as used in this application refers to two or more (including two).

[0079] "Parallel" includes not only the case of absolute parallelism but also the case of approximately parallelism as conventionally understood in engineering. "Perpendicular" includes not only the case of absolute perpendicularity but also the case of approximately perpendicularity as conventionally understood in engineering.

[0080] At present, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only applied to energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric transportation tools such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as aerospace. With the continuous expansion of the application fields of batteries, the market demand is also continuously increasing.

[0081] A battery generally refers to a single physical module that includes multiple battery cells to provide higher voltage and capacity. A battery cell is the smallest unit that makes up a battery, and multiple battery cells are usually electrically connected through a busbar component. During the cycling process of the battery cell, an electrochemical reaction occurs inside, causing the battery cell to expand. The expansion of the battery cell will exert a tensile force on the busbar component, triggering the risk of connection failure between the battery cell and the busbar component and affecting reliability. In order to reduce the risk of connection failure between the battery cell and the busbar component, the thickness of the busbar component can be reduced so that the busbar component can release stress through deformation when the battery cell expands, reducing the risk of connection failure between the battery cell and the busbar component. However, reducing the thickness of the busbar component will reduce the current-carrying area of the busbar component, that is, it will cause the temperature of the busbar component to rise and the resistance to increase, affecting the fast charging ability of the battery.

[0082] In view of this, the embodiments of the present application provide a battery that rationalizes the design of the battery cell and the busbar component to reduce the risk of connection failure between the battery cell and the busbar component, increase the current-carrying area of the busbar component, and improve the fast charging ability of the battery.

[0083] The battery described in the embodiments of the present application is applicable to electrical devices that use batteries. The electrical device can be a device that uses a battery as a power source or various energy storage systems with a battery as an energy storage element. The electrical device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, and so on. Among them, the electric toy can include fixed or mobile electric toys, such as a game console, an electric vehicle toy, an electric ship toy, and an electric aircraft toy, etc., and the spacecraft can include an airplane, a rocket, a space shuttle, and a spaceship, etc.

[0084] For the convenience of description, the following embodiments will be described by taking the electrical device as a vehicle as an example.

[0085] Figure 1 It is a schematic structural diagram of a vehicle provided by some embodiments of the present application.

[0086] As Figure 1 shown, a battery 2 is arranged inside the vehicle 1, and the battery 2 can be arranged at the bottom, head, or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1. For example, the battery 2 can be used as the operating power source of the vehicle 1.

[0087] The vehicle 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery 2 to supply power to the motor 4. For example, it is used for the power requirements during the start-up, navigation, and driving of the vehicle 1.

[0088] 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.

[0089] Figure 2 Schematic diagram of the battery provided for some embodiments of the present application.

[0090] Referring to Figure 2 , in some embodiments, the battery 2 includes a box body 20 and a plurality of battery cells 10 accommodated in the box body 20.

[0091] The battery cell 10 can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to be used.

[0092] Exemplarily, the battery cell 10 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium-metal battery cell, a sodium-metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0093] As an example, the battery cell 10 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc.

[0094] The plurality of battery cells 10 can be connected in series, in parallel, or in a series-parallel combination. A series-parallel combination means that there are both series and parallel connections among the plurality of battery cells 10. The plurality of battery cells 10 can be directly connected in series, in parallel, or in a series-parallel combination together, and then the whole formed by the plurality of battery cells 10 is accommodated in the box body 20; of course, it can also be that the plurality of battery cells 10 are first connected in series, in parallel, or in a series-parallel combination to form battery modules, and then the plurality of battery modules are connected in series, in parallel, or in a series-parallel combination to form a whole and are accommodated in the box body 20.

[0095] In some embodiments, the battery 2 includes a plurality of busbar components, and the plurality of busbars electrically connect the plurality of battery cells 10.

[0096] In some embodiments, the box body 20 can be a part of the chassis structure of the vehicle. For example, a part of the box body 20 can become at least a part of the floor of the vehicle, or a part of the box body 20 can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0097] Figure 3Explosion schematic diagram of a battery cell provided by some embodiments of the present application.

[0098] Referring to Figure 3 , in some embodiments, the battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12.

[0099] The housing 12 is a hollow structure, and an accommodation space for accommodating the electrode assembly 11 and the electrolyte is formed inside it. The shape of the housing 12 can be determined according to the specific shape of the electrode assembly 11. For example, if the electrode assembly 11 is a cuboid structure, a cuboid housing can be selected.

[0100] As an example, the housing 12 includes a housing body 121 and an end cap 122. The housing body 121 has an opening, and the end cap 122 is used to cover the opening.

[0101] The housing body 121 is a component for cooperating with the end cap 122 to form the internal cavity of the battery cell 10. The formed internal cavity can be used to accommodate the electrode assembly 11, the electrolyte, and other components.

[0102] The housing body 121 and the end cap 122 can be independent components. Exemplarily, an opening can be provided on the housing body 121, and the end cap 122 is covered at the opening to form the internal cavity of the battery cell 10.

[0103] The housing body 121 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing body 121 can be determined according to the specific shape and size of the electrode assembly 11. The material of the housing body 121 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc. The embodiments of the present application do not make special restrictions on this.

[0104] The shape of the end cap 122 can be adapted to the shape of the housing body 121 to cooperate with the housing body 121. The material of the end cap 122 can be the same as or different from that of the housing body 121. Optionally, the end cap 122 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, the end cap 122 is not easily deformed when being squeezed or collided, so that the battery cell 10 can have higher structural strength and the reliability performance can also be improved.

[0105] The end cap 122 is connected to the housing body 121 by welding, bonding, clamping or other means.

[0106] The housing 121 can be open at one end or both ends. In some examples, the housing 121 can be a structure with an opening on one side, and the end cap 122 is provided as one and covers the housing 121. In some other examples, the housing 121 can also be a structure with openings on both sides, and the end caps 122 are provided as two, and the two end caps 122 respectively cover the two openings of the housing 121.

[0107] The electrode assembly 11 is a component in the battery cell 10 where electrochemical reactions occur. One or more electrode assemblies 11 can be included in the housing 121.

[0108] In some embodiments, the electrode assembly 11 includes a positive electrode plate and a negative electrode plate. During the charging and discharging process of the battery cell 10, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate.

[0109] As an example, the parts of the positive electrode plate and the negative electrode plate with active substances constitute the main body 11a of the electrode assembly 11, the part of the positive electrode plate without active substance constitutes the positive electrode tab 11b, and the part of the negative electrode plate without active substance constitutes the negative electrode tab 11c. The positive electrode tab 11b and the negative electrode tab 11c can be located at one end of the main body 11a together or at both ends of the main body 11a respectively.

[0110] In some embodiments, the electrode assembly 11 further includes a separator. The separator is disposed between the positive electrode plate and the negative electrode plate, which can prevent short - circuit between the positive and negative electrodes and at the same time allow active ions to pass through.

[0111] In some embodiments, the electrode assembly 11 is a wound structure. The positive electrode plate and the negative electrode plate are wound into a wound structure.

[0112] In some embodiments, the electrode assembly 11 is a stacked structure.

[0113] As an example, multiple positive electrode plates and multiple negative electrode plates can be respectively provided, and the multiple positive electrode plates and the multiple negative electrode plates are alternately stacked.

[0114] As an example, multiple positive electrode plates can be provided, and the negative electrode plate is folded to form multiple stacked folding segments, and a positive electrode plate is clamped between adjacent folding segments.

[0115] As an example, both the positive electrode plate and the negative electrode plate are folded to form multiple stacked folding segments.

[0116] As an example, multiple separators can be provided and are respectively disposed between any adjacent positive electrode plates or negative electrode plates.

[0117] As an example, the separator can be continuously provided and is disposed between any adjacent positive electrode plates or negative electrode plates by folding or winding.

[0118] In some embodiments, the battery cell 10 further includes electrode terminals 13 disposed on the outer casing 12; the electrode terminals 13 can be used to electrically connect to the electrode assembly 11 to input or output electrical energy.

[0119] In some embodiments, the electrode terminals 13 are electrically connected to the tab. Exemplarily, there are two electrode terminals 13, and the two electrode terminals 13 are respectively electrically connected to the positive tab 11b and the negative tab 11c.

[0120] Figure 4 Schematic diagram of a battery provided in some embodiments of the present application; Figure 5 is Figure 4 Enlarged schematic diagram at the circular frame; Figure 6 is Figure 5 Schematic structural diagram of the first busbar component shown; Figure 7 Connection schematic diagram of the battery cell and the first busbar component provided in some embodiments of the present application; Figure 8 is Figure 3 Schematic diagram of the electrode assembly described; Figure 9 is Figure 8 Cross-sectional schematic diagram of the electrode assembly shown; Figure 10 Cross-sectional schematic diagram of the negative electrode plate of the battery cell provided in some embodiments of the present application; Figure 11 Cross-sectional schematic diagram of the positive electrode plate of the battery cell provided in some embodiments of the present application; Figure 12 Cross-sectional schematic diagram of the negative electrode plate of the battery cell provided in some other embodiments of the present application.

[0121] Referring to Figures 4 to 12 , embodiments of the present application provide a battery, which includes a plurality of battery cells 10 and a plurality of busbar components 30, and the plurality of busbar components 30 electrically connect the plurality of battery cells 10.

[0122] The plurality of busbar components 30 can connect the plurality of battery cells 10 in series, parallel or in a hybrid connection.

[0123] The plurality of busbar components 30 can have the same structure or different structures.

[0124] In some embodiments, the plurality of battery cells 10 are arranged along the thickness direction X of the battery cell 10. The battery cell 10 includes an outer casing 12 and an electrode assembly 11 accommodated in the outer casing 12. The expansion pressure of the battery cell 10 in the thickness direction X is 0.5 MPa - 2.4 MPa.

[0125] In some embodiments, the battery includes a first busbar component 30a, and the first busbar component 30a is electrically connected to at least two battery cells 10 arranged along the thickness direction X. The first busbar component 30a is a multi-layer structure.

[0126] The electrode assembly 11 includes a positive electrode sheet 111, a negative electrode sheet 112, and a separator 113 disposed between the positive electrode sheet 111 and the negative electrode sheet 112. The positive electrode sheet 111 includes a positive electrode current collector 1111 and a positive electrode film layer 1112 disposed on at least one side of the positive electrode current collector 1111. The positive electrode film layer 1112 includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate having an olivine structure. The negative electrode sheet 112 includes a negative electrode current collector 1121 and a negative electrode film layer 1122 disposed on at least one side of the negative electrode current collector 1121. The negative electrode film layer 1122 includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

[0127] The battery cells 10 can be arranged in a single row or in multiple rows. Exemplarily, a single row of battery cells 10 can form a battery cell row 100, and the battery cell row 100 includes at least two battery cells 10 arranged along the thickness direction X.

[0128] The battery cell 10 can include one or more electrode assemblies 11. Optionally, the electrode assemblies 11 are arranged along the thickness direction X.

[0129] 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.

[0130] As an example, the expansion pressure of the battery cell 10 can be measured in the following manner: In an ambient temperature of 45°C, the battery cell 10 is discharged at a constant current discharge rate of 1C to 2.0V; The battery cell 10 is clamped between two clamping plates, where the two clamping plates are respectively located on both sides of the battery cell 10 along the thickness direction X and cover the large surface 10a (the large surface 10a is the surface on one side of the battery cell 10 along the thickness direction X); In an ambient temperature of 45°C, the battery cell is charged at a constant current charge rate of 0.8C to 3.8V, and the pressure exerted by the battery cell on the clamping plate is detected and recorded; The battery cell is cyclically charged and discharged according to the above charging strategy and charging strategy until the battery cell is cycled to 70% SOH (i.e., the capacity retention rate of the battery cell = the discharge capacity of the battery cell / the nominal capacity of the battery cell = 70%), and the maximum pressure exerted by the battery cell on the clamping plate is recorded; The expansion pressure Q of the battery cell in the thickness direction is calculated as: maximum pressure / large surface area.

[0131] In an 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 the negative electrode film layer 1122 may be provided on both sides of the negative electrode current collector 1121.

[0132] Optionally, the negative electrode film layer 1122 is provided on both surfaces of the negative electrode current collector 1121 that are opposite to each other in the thickness direction of the negative electrode current collector 1121. The negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 may use the same negative electrode active material or different negative electrode active materials; the thicknesses of the negative electrode film layers 1122 on the two surfaces of the negative electrode current collector 1121 may be the same or different.

[0133] Exemplarily, the negative electrode current collector 1121 may be a metal foil or a composite current collector. As an example of the metal foil, at least one foil of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0134] 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.

[0135] The positive electrode current collector 1111 has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer 1112 is provided on any one or both of the two opposite surfaces of the positive electrode current collector 1111.

[0136] Exemplarily, the positive electrode current collector 1111 may be a metal foil or a composite current collector. As an example of the metal foil, at least one foil of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0137] The lithium-containing phosphate has high cycle stability. Using the lithium-containing phosphate as the positive electrode active material can improve the cycle attenuation of the battery cell 10 caused by excessive temperature rise during rapid charging.

[0138] The multiple current collecting components 30 can all be the first current collecting components 30a, or some of them can be the first current collecting components 30a.

[0139] The expansion pressure of the battery cell 10 is related to the compactness of the electrode assembly 11. In the embodiments of the present application, the battery cell 10 can be allowed to have an expansion pressure greater than or equal to 0.5 MPa in the thickness direction X, so as to improve the compactness of the electrode assembly 11 and increase 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, which can limit the deformation of the electrode assembly 11 during cycling, reduce the risk of wrinkling deformation of the separator of the electrode assembly 11 and the risk of increased local spacing between the positive electrode sheet and the negative electrode sheet, reduce polarization, and improve the cycling performance of the battery cell 10.

[0140] The first current collecting component 30a has a multi-layer structure, and each layer structure of the first current collecting component 30a can transmit current, so that the first current collecting component 30a can have a relatively large current-carrying area, thereby reducing the heat generation of the first current collecting component 30a and improving the fast charging ability of the battery 2.

[0141] On the premise that the current-carrying area meets the requirements, setting the first current collecting component 30a as a multi-layer structure can reduce the thickness of each layer structure of the first current collecting component 30a. During the cycling process of the battery cell 10, expansion will occur, thus stretching a layer structure of the first current collecting component 30a connected to the battery cell 10. A layer structure of the first current collecting component 30a has a relatively small thickness, and it is easy to deform to adapt to the expansion deformation of the battery cell 10, so when the expansion pressure of the battery cell 10 is 0.5 MPa - 2.4 Mpa, the risk of the connection between the battery cell 10 and the first current collecting component 30a being torn is reduced, and the reliability of the battery 2 is improved.

[0142] The embodiments of the present application adopt the first current collecting component with a multi-layer structure, which can adapt to the expansion of the battery cell and take into account the current-carrying capacity and deformability of the first current collecting component, thereby improving the reliability and fast charging ability of the battery.

[0143] In some embodiments, the first current collecting component 30a includes a first current collecting layer 31 and a second current collecting layer 32 that are stacked and connected, and the first current collecting layer 31 is connected to at least two battery cells 10 arranged along the thickness direction X.

[0144] The first current collecting layer 31 and the second current collecting layer 32 can be an integrally formed structure. Alternatively, the first current collecting layer 31 and the second current collecting layer 32 can also be independently formed and connected by welding or other means.

[0145] Both the first current collecting layer 31 and the second current collecting layer 32 can conduct current, so that the first current collecting component 30a has a relatively large current-carrying area, thereby reducing the heat generation of the first current collecting component 30a and improving the fast charging ability and reliability of the battery. On the premise that the current-carrying area meets the requirements, setting the first current collecting component 30a as a double-layer structure can reduce the requirement for the thickness of the first current collecting layer 31. During the cycling process of the battery cell 10, expansion will occur, thereby stretching the first current collecting layer 31. The first current collecting layer 31 has a relatively small thickness and is easy to deform to adapt to the deformation of the battery cell 10, reducing the risk that the connection between the battery cell 10 and the first current collecting layer 31 is torn, and improving the reliability of the battery 2.

[0146] In some embodiments, the battery cell 10 includes electrode terminals 13 disposed on the outer casing 12, and the electrode terminals 13 are electrically connected to the electrode assembly 11. The first current collecting layer 31 is connected to the electrode terminals 13 of the battery cell 10.

[0147] Optionally, the first current collecting layer 31 is welded to the electrode terminals 13.

[0148] In some embodiments, the portion of the first current collecting layer 31 that does not overlap with the second current collecting layer 32 is connected to the electrode terminals 13.

[0149] The second current collecting layer 32 can avoid the connection between the first current collecting layer 31 and the electrode terminals 13, so as to reduce the influence of the second current collecting layer 32 on the connection between the first current collecting layer 31 and the electrode terminals 13 when the battery cell expands, reduce the risk that the connection between the electrode terminals 13 and the first current collecting layer 31 is torn, and improve the reliability of the battery 2. Additionally, when assembling the battery cell 10 and the first current collecting component 30a, the second current collecting layer 32 does not cover the area of the first current collecting layer 31 for connecting to the electrode terminals 13, which can reduce the assembly difficulty.

[0150] In some embodiments, the first current collecting layer 31 is welded to the electrode terminals 13, and the welding area between the first current collecting layer 31 and the electrode terminals 13 is greater than or equal to 60 mm 2 .

[0151] Exemplarily, the first current collecting layer 31 is welded to the electrode terminals 13 to form welding imprints; the welding area can be the area of the projection of the welding imprints along the thickness direction of the first current collecting layer. Optionally, the welding imprints are circular rings, and the inner radius and outer radius of the welding imprints are R 1 and R 2 , respectively, then the welding area is π×(R 2 2 - R 1 2 ).

[0152] Exemplarily, the welding area between the first current collecting layer 31 and the electrode terminals 13 is 60 mm2 、 70 mm 2 、 80 mm 2 、 90 mm 2 、 100 mm 2 、 110 mm 2 or 120 mm 2 。

[0153] The embodiment of the present application can provide a relatively large current-carrying area between the first current collecting layer 31 and the electrode terminal 13, thereby reducing the heat generation at the welding point, reducing the temperature rise of the first current collecting layer 31 during fast charging, and improving the fast charging ability of the battery.

[0154] In some embodiments, the second current collecting layer 32 does not cover the welding mark.

[0155] In some embodiments, in the stacking direction of the first current collecting layer 31 and the second current collecting layer 32, the second current collecting layer 32 partially overlaps with the electrode terminal 13, which can shorten the conduction path between the second current collecting layer 32 and the electrode terminal 13, thereby reducing the resistance and heat generation.

[0156] In some embodiments, the first current collecting layer 31 and the second current collecting layer 32 are stacked along the height direction Z of the battery cell 10. In other words, the stacking direction of the first current collecting layer 31 and the second current collecting layer 32 is parallel to the height direction Z. Exemplarily, the height direction Z is perpendicular to the thickness direction X.

[0157] In some embodiments, the second current collecting layer 32 can be disposed on the side of the first current collecting layer 31 facing the battery cell 10, or can be disposed on the side of the first current collecting layer 31 facing away from the battery cell 10.

[0158] In some embodiments, the first current collecting member 30a includes at least one bending portion 33, and the bending portion 33 connects the first current collecting layer 31 and the second current collecting layer 32.

[0159] The bending portion 33 can be one or more.

[0160] The bending portion 33 can connect the first current collecting layer 31 and the second current collecting layer 32 and transmit current between the first current collecting layer 31 and the second current collecting layer 32, thereby improving the current-carrying capacity of the first current collecting member 30a.

[0161] In some embodiments, the first current collecting layer 31 includes a first current collecting portion 311, a second current collecting portion 312, and a first buffer portion 313. The first current collecting portion 311 and the second current collecting portion 312 are disposed along the thickness direction X and are connected to different battery cells 10, and the first buffer portion 313 connects the first current collecting portion 311 and the second current collecting portion 312. At least one of the first current collecting portion 311 and the second current collecting portion 312 is connected to the bending portion 33.

[0162] The first current collecting part 311 can be connected to the electrode terminal 13 of one battery cell 10, or can be simultaneously connected to the electrode terminals 13 of at least two battery cells 10. The second current collecting part 312 can be connected to the electrode terminal 13 of one battery cell 10, or can be simultaneously connected to the electrode terminals 13 of at least two battery cells 10.

[0163] During the cycling of the battery cell 10, the battery cell 10 expands and applies a tensile force to the first current collecting layer 31; the first buffer part 313 can release stress through deformation, thereby reducing the force on the connection between the first current collecting part 311 and the battery cell 10 and the force on the connection between the second current collecting part 312 and the battery cell 10, and reducing the risk of connection failure between the first current collecting layer 31 and the battery cell 10.

[0164] In some embodiments, the bending part 33 and the first buffer part 313 are arranged to avoid each other. The bending part 33 is not directly connected to the first buffer part 313, thereby reducing the influence of the bending part 33 on the deformation of the first buffer part 313 and reducing the difficulty of deformation of the first buffer part 313.

[0165] In some embodiments, the first current collecting layer 31 and the second current collecting layer 32 are arranged in a fitting manner. Optionally, except for the initial bending part 33, there is no other fixed connection relationship between the first current collecting layer 31 and the second current collecting layer 32. Alternatively, a conductive adhesive can be provided between the first current collecting layer 31 and the second current collecting layer 32.

[0166] In some embodiments, the first current collecting part 311 is located above the electrode terminal 13 of the battery cell 10, and the second current collecting part 312 is located above the electrode terminal 13 of the battery cell 10.

[0167] In some embodiments, the first buffer part 313 includes an arch structure.

[0168] In some embodiments, the first current collecting part 311 is connected to the second current collecting layer 32 through at least one bending part 33, and the second current collecting part 312 is connected to the second current collecting layer 32 through at least one bending part 33.

[0169] In some embodiments, the second current collecting layer 32 includes a first stacked part 321, a second stacked part 322, and a second buffer part 323. The first stacked part 321 is stacked with the first current collecting part 311 and connected through at least one bending part 33. The second stacked part 322 is stacked with the second current collecting part 312 and connected through at least one bending part 33. The second buffer part 323 connects the first stacked part 321 and the second stacked part 322. In the stacking direction of the first current collecting layer 31 and the second current collecting layer 32, the second buffer part 323 and the first buffer part 313 at least partially overlap.

[0170] During the cycling of the battery cell 10, the battery cell 10 expands and applies a tensile force to the first current collecting layer 31; both the first buffer portion 313 and the second buffer portion 323 can release stress through deformation, thereby reducing the risk of connection failure between the first current collecting layer 31 and the battery cell 10. The second buffer portion 323 at least partially overlaps with the first buffer portion 313, so that the deformation regions of the first buffer portion 313 and the second buffer portion 323 can be close, thereby reducing the risk of interference between the first buffer portion 313 and the second buffer portion 323 and other parts during deformation.

[0171] In some embodiments, the second buffer portion 323 and the first buffer portion 313 are disposed in a fitting manner. The embodiments of the present application can save space and improve the current-carrying capacity.

[0172] In some embodiments, the outer surface of the battery cell 10 includes two large surfaces 10a and two narrow surfaces 10b. The two large surfaces 10a are oppositely disposed along the thickness direction X, and the two narrow surfaces 10b are oppositely disposed along the width direction Y of the battery cell. The two ends of the large surface 10a along the width direction Y are connected to the two narrow surfaces 10b. The area of the large surface 10a is larger than the area of the narrow surface 10b.

[0173] In some embodiments, the thickness direction X, the width direction Y, and the height direction Z are perpendicular to each other in pairs.

[0174] In some embodiments, a plurality of battery cell columns 100 are arranged along the width direction Y.

[0175] In some embodiments, the expansion pressure of the battery cell 10 in the thickness direction X is 1.5 MPa - 2.0 MPa.

[0176] The embodiments of the present application limit the expansion pressure of the battery cell 10 in the thickness direction X to 1.5 MPa - 2.0 MPa, so as to reduce the tensile force of the battery cell on the first current collecting component during the cycling of the battery cell, reduce the risk of connection failure between the battery cell and the first current collecting component, and improve the reliability of the battery.

[0177] In some embodiments, the thickness of the first current collecting layer 31 is 1 mm - 2.5 mm, and may be optionally 1.2 mm - 1.8 mm.

[0178] As an example, the thickness of the first current collecting layer 31 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.

[0179] In the embodiments of the present application, the thickness of the first current collecting layer 31 is selected according to the expansion pressure of the battery cell 10, which can balance the current-carrying capacity and deformability of the first current collecting layer 31 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0180] In some embodiments, the thickness of the second current collecting layer 32 is 1 mm - 2.5 mm, and can be optionally 1.2 mm - 1.8 mm. As an example, the thickness of the second current collecting layer 32 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.

[0181] The thickness of the second current collecting layer 32 can be selected according to the thickness of the first current collecting layer 31 and the current-carrying capacity of the battery for the first current collecting component. Exemplarily, when the thickness of the first current collecting layer 31 is small, the second current collecting layer 32 can have a thickness greater than that of the first current collecting layer 31 to improve the current-carrying capacity of the first current collecting component.

[0182] In some embodiments, the volume energy density of the battery cell 10 is 390 Wh / L - 450 Wh / L, and the thickness of the first current collecting layer 31 is less than or equal to 2.5 mm.

[0183] The volume energy density of the battery cell 10 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art.

[0184] The expansion of the battery cell 10 is related to its volume energy density. In the present application, the thickness of the first current collecting layer 31 is designed according to the volume energy density of the battery cell 10, which can balance the current-carrying capacity and deformability of the first current collecting layer 31 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0185] In some embodiments, the volume energy density of the battery cell 10 is 450 Wh / L - 480 Wh / L, and the thickness of the first current collecting layer 31 is less than or equal to 2.2 mm.

[0186] The expansion of the battery cell 10 is related to its volume energy density. For the battery 2 using the battery cell 10 with a high volume energy density, it is necessary to reduce the thickness of the first current collecting layer 31. In the embodiments of the present application, the thickness of the first current collecting layer 31 is designed according to the volume energy density of the battery cell 10, which can balance the current-carrying capacity and deformability of the first current collecting layer 31 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0187] In some embodiments, the negative electrode active material further includes a silicon-based material. The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% - 6%; the thickness of the first current collecting layer 31 is 1.2 mm - 2.2 mm, and the thickness of the second current collecting layer 32 is 1.2 mm - 2.2 mm.

[0188] As an example, the mass content of silicon element in the silicon-based material in the negative electrode active material is 1%, 2%, 3%, 4%, 5% or 6%. As an example, the thickness of the first current collecting layer 31 is 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm or 2.2 mm. As an example, the thickness of the second current collecting layer 32 is 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm or 2.2 mm.

[0189] By introducing the silicon-based material, the capacity of the negative electrode sheet 112 can be improved, and the energy density of the battery cell 10 can be increased. Introducing the silicon-based material will also increase the expansion of the negative electrode sheet 112 during the cycling process. By designing the thicknesses of the first current collecting layer 31 and the second current collecting layer 32 in combination with the content of silicon element, the risk of connection failure between the first current collecting layer 31 and the battery cell 10 caused by introducing the silicon-based material can be reduced, and the requirement for the over-current capacity of the first current collecting component 30a can be met.

[0190] In some embodiments, the first current collecting layer 31 includes a first current collecting portion 311, a second current collecting portion 312, and a first buffer portion 313 connecting the first current collecting portion 311 and the second current collecting portion 312. The first current collecting portion 311 and the second current collecting portion 312 are arranged along the thickness direction X and are connected to different battery cells 10. In the stacking direction of the first current collecting layer 31 and the second current collecting layer 32, the first buffer portion 313 protrudes from the first current collecting portion 311 and the second current collecting portion 312. The first current collecting layer 31 is provided with a concave portion 314 at a position corresponding to the first buffer portion 313.

[0191] By providing the concave portion 314, the strength of the first buffer portion 313 can be reduced, facilitating the deformation of the first buffer portion 313 when the battery cell 10 expands.

[0192] In some embodiments, the volume energy density of the battery cell 10 is 390 Wh / L - 450 Wh / L, and the depth H of the concave portion 314 2 is 1.2 mm - 2.5 mm.

[0193] The swelling of the battery cell 10 is related to its volumetric energy density. In this application, the depth of the recess 314 is designed according to the volumetric energy density of the battery cell 10, so as to balance the current-carrying capacity and deformability of the first buffer portion 313 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0194] In some embodiments, the volumetric energy density of the battery cell 10 is 450 Wh / L - 480 Wh / L, and the depth of the recess 314 is 1 mm - 2.2 mm.

[0195] The swelling of the battery cell 10 is related to its volumetric energy density. For the battery 2 using the battery cell 10 with a high volumetric energy density, it is necessary to reduce the difficulty of deforming the first buffer portion 313. In the embodiments of this application, the depth of the recess 314 is designed according to the volumetric energy density of the battery cell 10, so as to balance the current-carrying capacity and deformability of the first buffer portion 313 to a certain extent, thereby improving the fast charging ability and reliability of the battery 2.

[0196] In some embodiments, the battery 2 further includes a box body 20. The box body 20 is used to accommodate a plurality of battery cells 10. The box body 20 includes at least two limiting beams 21, and two adjacent limiting beams 21 are arranged along the thickness direction X, and a plurality of battery cells 10 are arranged between the adjacent limiting beams 21.

[0197] As an example, at least one battery cell row 100 is provided between any two adjacent limiting beams 21.

[0198] The limiting beam 21 can be used to limit the swelling deformation of the battery cell 10 in the thickness direction X. The limiting beam 21 can directly abut against the battery cell 10 in the thickness direction X; alternatively, other components can also be provided between the limiting beam 21 and the battery cell 10, that is, the limiting beam 21 limits the swelling of the battery cell 10 through this component.

[0199] The limiting beam 21 can limit the swelling of the battery cell 10 during the cycling of the battery, thereby reducing the pulling force exerted by the battery cell 10 on the first current collecting component 30a, reducing the risk of connection failure between the battery cell 10 and the first current collecting component 30a, and improving the reliability of the battery.

[0200] In some embodiments, the electrode assembly 11 includes two first surfaces 11d and two second surfaces 11e. The two first surfaces 11d are oppositely arranged along the thickness direction X, the two second surfaces 11e are oppositely arranged along a direction perpendicular to the thickness direction X, and the second surface 11e connects the two first surfaces 11d. The area of the first surface 11d is larger than the area of the second surface 11e.

[0201] The larger first surface 11d is opposite to the limiting beam 21 in the thickness direction X, so that when the electrode assembly 11 expands, the stress area of the limiting beam 21 can be increased, and the deformation of the limiting beam 21 can be reduced.

[0202] In some embodiments, the limiting beam 21 extends in the width direction Y.

[0203] In some embodiments, the two second surfaces 11e are arranged opposite to each other in the width direction Y.

[0204] In some embodiments, the main body portion 11a includes two first surfaces 11d, two second surfaces 11e and two third surfaces 11f; the two third surfaces 11f are located at both ends of the battery cell 10 in the height direction Z, and the third surfaces 11f are connected to the two first surfaces 11d and the two second surfaces 11e.

[0205] The positive electrode tab 11b and the negative electrode tab 11c extend from the same third surface 11f, or the positive electrode tab 11b and the negative electrode tab 11c extend from two third surfaces 11f respectively.

[0206] In some embodiments, at least a part of the second surface 11e is arc-shaped. Optionally, the electrode assembly 11 is a wound structure, and the second surface 11e is an arc surface.

[0207] In some embodiments, the large surface 10a is parallel to the first surface 11d.

[0208] In some embodiments, the battery cell 10 is a square shell battery cell. Optionally, the narrow surface 10b is perpendicular to the large surface 10a.

[0209] In some embodiments, a part of the negative electrode current collector 1121 is not covered by the negative electrode film layer 1122; the part of the negative electrode current collector 1121 not covered by the negative electrode film layer 1122 can be used to form the negative electrode tab 11c.

[0210] In some embodiments, the thickness of the negative electrode current collector 1121 is 4 μm to 6 μm. Exemplarily, the thickness of the negative electrode current collector 1121 is 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm or the range composed of any two of the above values.

[0211] In some embodiments, the compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 . Exemplarily, when the battery cell 10 is in a 100% state of charge, the compaction density of the negative electrode film layer 1122 is 1.15 g / cm 3 、1.18 g / cm 3 、1.20 g / cm 3 、1.22 g / cm3 , 1.25 g / cm 3 , 1.28 g / cm 3 , 1.3 g / cm 3 , 1.32 g / cm 3 , 1.35 g / cm 3 , 1.36 g / cm 3 or a range composed of any two of the above values.

[0212] Exemplarily, 100% SOC (state of charge) and 0% SOC are defined as follows: The battery cell is charged at a constant current charge rate of 0.33C to the upper limit voltage of battery charge, and then charged at a constant voltage to 0.05C, corresponding to the state of 100% SOC of the battery cell; the battery cell is discharged at a constant current discharge rate of 0.33C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell. Demonstratively, the upper limit voltage of battery charge can be 3.8V; the cut-off voltage of battery discharge can be 2.0V.

[0213] Exemplarily, the compaction density of the negative electrode film layer of the battery cell in the 100% charged state has the meaning well known in the art, that is, the negative electrode sheet is disassembled from the battery cell at 100% SOC, and the compaction density of the negative electrode film layer is measured; for example, a single-sided coated negative electrode sheet (if it is a double-sided coated negative electrode sheet, one side of the negative electrode film layer can be wiped off first) is punched into small round pieces with an area of S1, weighed, recorded as M1, and its thickness H1 is measured. Then the negative electrode film layer of the above weighed negative electrode sheet is wiped off, the weight of the negative electrode current collector is weighed, recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the negative electrode film layer = (the weight M1 of the negative electrode sheet - the weight M0 of the negative electrode current collector) / S1, the thickness of the negative electrode film layer = the thickness H1 of the negative electrode sheet - the thickness H0 of the negative electrode current collector, and the compaction density of the negative electrode film layer = the single-sided coating weight of the negative electrode film layer / the thickness of the negative electrode film layer.

[0214] The compaction density of the negative electrode film layer 1122 is related to the swelling of the battery cell 10 in the 100% charged state. Limiting the compaction density of the negative electrode film layer 1122 to 1.15 g / cm 3 to 1.36 g / cm 3 can, to a certain extent, balance the energy density and swelling pressure of the battery cell 10, reduce the deformation of the battery cell 10, and reduce the risk of connection failure between the battery cell 10 and the busbar components.

[0215] When the compaction density of the negative electrode film layer 1122 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and since the negative electrode active materials in the negative electrode film layer 1122 are stacked relatively tightly, the contact resistance between particles is small, which can reduce the resistance of the negative electrode sheet 112, thereby reducing heat generation.

[0216] When the compaction density of the negative electrode film layer 1122 is within the above range, the fast charging ability of the battery cell 10 can be improved. When the compaction density of the negative electrode film layer 1122 is small, the porosity of the negative electrode sheet 112 can be increased, the swelling of the negative electrode sheet can be slowed down, and the swelling pressure of the battery cell 10 can be reduced.

[0217] In some embodiments, the compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.25 g / cm 3 to 1.36 g / cm 3 , which can improve the energy density of the battery cell 10.

[0218] In some embodiments, the single-sided coating weight of the negative electrode film layer 1122 is 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 . Exemplarily, the single-sided coating weights of the negative electrode film layer 1122 are 90 mg / 1540.25 mm 2 , 92 mg / 1540.25 mm 2 , 95 mg / 1540.25 mm 2 , 96 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 102 mg / 1540.25 mm 2 , 104 mg / 1540.25 mm 2 , 105 mg / 1540.25 mm 2 , 108 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 112 mg / 1540.25 mm 2 , 114 mg / 1540.25 mm 2 , 115 mg / 1540.25 mm 2 , 116 mg / 1540.25 mm 2 , 118 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 122 mg / 1540.25 mm 2 , 125 mg / 1540.25 mm 2 , 128 mg / 1540.25 mm 2, 130 mg / 1540.25 mm 2 , 132 mg / 1540.25 mm 2 , 135 mg / 1540.25 mm 2 , 137 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 142 mg / 1540.25 mm 2 , 145 mg / 1540.25 mm 2 , 148 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 152 mg / 1540.25 mm 2 , 155 mg / 1540.25 mm 2 , 160 mg / 1540.25 mm 2 , 165 mg / 1540.25 mm 2 , 167 mg / 1540.25 mm 2 , 170 mg / 1540.25 mm 2 Or a range composed of any two of the above values.

[0219] The single-sided coating weight of the negative electrode film layer 1122 is related to the swelling of the negative electrode film layer. Limiting the single-sided coating weight of the negative electrode film layer 1122 to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , can take into account the energy density and swelling pressure of the battery cell 10 to a certain extent, reduce the deformation of the battery cell 10, and reduce the risk of connection failure between the battery cell 10 and the busbar component.

[0220] In addition, limiting the single-sided coating weight of the negative electrode film layer 1122 to 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 , can also limit the heat generation of the negative electrode sheet 112 per unit area, reduce the temperature rise of the battery cell 10, especially the temperature rise during fast charging.

[0221] In some embodiments, the single-sided coating weight of the negative electrode film layer 1122 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 2 , to further take into account the energy density and swelling pressure of the battery cell 10.

[0222] In some embodiments, the porosity of the negative electrode sheet 112 is 27% - 40%. As an example, the porosity of the negative electrode sheet 112 can be 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.

[0223] The porosity of the negative electrode sheet can be the percentage of the pore volume in the negative electrode sheet to the total volume of the negative electrode sheet. Exemplarily, when the battery cell is in a 0% state of charge, a double-sided coated negative electrode sheet is taken; the porosity of the negative electrode sheet is measured by an AccuPyc Ⅱ 1340 true density meter in accordance with the national standard GB / T 24586-2009.

[0224] In the embodiments of the present application, the porosity of the negative electrode sheet 112 is greater than or equal to 27%, which can provide space for impurities generated by side reactions in the negative electrode sheet 112, slow down the swelling of the negative electrode sheet 112, reduce the swelling pressure of the battery cell 10, reduce the deformation of the battery cell 10, improve the cycling performance of the battery cell 10, and reduce the risk of connection failure between the battery cell and the busbar component. The porosity of the negative electrode sheet 112 is less than or equal to 40%, which can balance the energy density of the battery cell 10.

[0225] In some embodiments, the carbon-based material includes graphite particles, and the graphitization degree of the graphite particles is 92.0% to 94.5%. Exemplarily, the graphitization degree of the graphite particles is 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5% or the range composed of any two of the above values.

[0226] When the graphitization degree of the graphite particles is within the above range, the conductive performance of the graphite particles is relatively excellent, which can reduce the heat generation of the negative electrode sheet 112 and the battery cell 10; and can improve the fast charging performance of the battery cell 10.

[0227] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. The artificial graphite and natural graphite have good electrical conductivity, which can reduce the heat generation of the negative electrode sheet 112 during charging and improve the fast charging performance of the battery cell 10.

[0228] In some embodiments, the negative electrode active material further includes a silicon-based material. The introduction of the silicon-based material can improve the capacity of the negative electrode active material and increase the energy density of the battery cell 10.

[0229] In some embodiments, the mass content of silicon element in the silicon-based material in the negative electrode active material is from 0.3% to 10%, and can be optionally from 1% to 6%. Exemplarily, the mass content of silicon element in the negative electrode active material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10% or a range composed of any two of the above values.

[0230] Introducing the silicon-based material into the negative electrode sheet 112 can not only improve the capacity, but also increase the expansion of the negative electrode sheet 112. Therefore, limiting the mass content of silicon element in the negative electrode active material to be from 0.3% to 10% can, to a certain extent, balance the energy density and expansion of the battery cell 10, reduce the deformation of the battery cell 10, lower the risk of connection failure between the battery cell and the busbar component, and improve the cycling performance of the battery cell 10.

[0231] In this application, the qualitative and quantitative determination of each substance or each element can be detected by suitable equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc. And those skilled in the art can also adaptively change some detection steps / instrument parameters, etc. from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used jointly for qualitative or quantitative determination.

[0232] For example, the silicon-based material can be combined with the General Rules of X-ray Diffraction Analysis of JIS / K0131-1996 to perform X-ray powder diffraction testing and qualitative analysis on the negative electrode sheet or the negative electrode active material.

[0233] In some embodiments, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.

[0234] In some embodiments, the silicon-based material includes at least one of silicon oxide compound and silicon-carbon composite.

[0235] In some embodiments, in addition to the carbon-based material and the optional silicon-based material, the negative electrode active material may further include at least one of a tin-based material and lithium titanate. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.

[0236] In some embodiments, the negative electrode film layer 1122 in the embodiments of the present application includes at least one film layer. In other words, the negative electrode film layer 1122 can adopt a single-layer film layer or at least two-layer film layers. Optionally, the negative electrode film layer 1122 includes at least two-layer film layers.

[0237] When the negative electrode film layer 1122 adopts a single-layer film layer, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. When adopting a single-layer film layer, the volume average particle diameter Dv50 of the negative electrode active material is 8.2 μm to 13.5 μm. Exemplarily, the volume average particle diameter Dv50 of the negative electrode active material is 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm or a range composed of any two of the above values.

[0238] When the negative electrode film layer 1122 adopts at least two-layer film layers, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. The silicon-based material can be located in one of the at least two-layer film layers or in at least two of the at least two-layer film layers. The negative electrode film layer 1122 can include two-layer film layers, three-layer film layers, four-layer film layers, or even more film layers.

[0239] In some embodiments, the negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222. The second negative electrode film layer 11222 is disposed between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material disposed in the first negative electrode film layer 11221 and a second negative electrode active material disposed in the second negative electrode film layer 11222. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials.

[0240] The interface between the first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be regular or irregular; optionally it is irregular.

[0241] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be differentially set, so as to balance the expansion and capacity of the negative electrode film layer 1122 to a certain extent; double-layer coating can construct the pore difference of the negative electrode film layer 1122, reduce the ion transport tortuosity, reduce side reactions, and improve the fast charging performance of the battery cell 10.

[0242] Artificial graphite can have a relatively small volume average particle size Dv50, which can, on the one hand, shorten the solid-phase transport path of lithium ions and improve the fast charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material.

[0243] In some embodiments, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is from 3:7 to 7:3. As an example, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is 3:7, 4:6, 5:5, 6:4 or 7:3.

[0244] Optionally, the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222 is from 4:6 to 6:4.

[0245] By adjusting the thickness ratio of the first negative electrode film layer 11221 to the second negative electrode film layer 11222, the gradient pore difference between the upper and lower layers can be further increased, the tortuosity of lithium ion transport can be reduced, and the fast charging ability of the battery cell 10 can be improved.

[0246] In some embodiments, the thickness of the first negative electrode film layer 11221 is less than or equal to the thickness of the second negative electrode film layer 11222, which can further improve the fast charging ability of the battery cell 10.

[0247] In some embodiments, the first negative electrode active material is granular and the second negative electrode active material is granular.

[0248] 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.

[0249] The difference in the particle sizes of the first negative electrode active material and the second negative electrode active material can improve the fast charging performance of the battery cell 10; during fast charging, the overpotential of the first negative electrode film layer 11221 is usually relatively high, and the bottleneck of fast charging mainly lies in the first negative electrode film layer 11221. In the embodiments of the present application, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transport path of ions, improve the fast charging performance, and can improve the problem of ion precipitation on the surface layer of the negative electrode sheet 112. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film layer 11222. During charging, the pores can absorb expansion, reduce the expansion amount of the negative electrode film layer 1122, reduce the force exerted by the battery cell 10 on the first current collecting component 30a, and reduce the risk of connection failure between the battery cell 10 and the first current collecting component 30a.

[0250] In some embodiments, the volume-average particle size Dv50 of the first negative electrode active material is 7.8 μm - 14.3 μm, and may be optionally 7.8 μm - 11.3 μm. Exemplarily, the volume-average particle size Dv50 of the first negative electrode active material is 7.8 μm, 8.0 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.3 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, 13.8 μm, 14 μm, 14.1 μm, 14.3 μm or a range composed of any two of the above values.

[0251] The volume-average particle size Dv50 of the first negative electrode active material is set to 7.8 μm - 14.3 μm. On the one hand, it can shorten the solid-phase transmission path of lithium ions and improve the fast-charging performance; on the other hand, the material is not prone to agglomeration during the preparation process, which can improve the stability of the material; on the further hand, the first negative electrode active material within the above volume-average particle size range can cooperate with the second negative electrode active material, which is beneficial to constructing the gradient pore difference between the first negative electrode film layer 11221 and the second negative electrode film layer 11222, reducing the tortuosity of lithium-ion transmission, and improving the fast-charging performance of the battery cell 10.

[0252] The volume-average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume-average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. It can be detected by using the equipment and methods well-known in the art. For example, taking the negative electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer.

[0253] In some embodiments, the volume-average particle size Dv50 of the second negative electrode active material is 9.5 μm - 18.5 μm, and may be optionally 9.5 - 14.6 μm.

[0254] Exemplarily, the volume-average particle size Dv50 of the second negative electrode active material is 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 14.6 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm or a range composed of any two of the above values.

[0255] The volume average particle size Dv50 of the second negative electrode active material is from 9.5 μm to 18.5 μm, which can make the pores of the second negative electrode film layer 11222 richer, be beneficial to improving the fast charging ability of the battery cell 10, and reducing the swelling of the negative electrode film layer 1122 during charging.

[0256] 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 from 7.8 μm to 14.3 μm, and can be from 7.8 μm to 11.3 μm. Optionally, the first negative electrode active material includes artificial graphite.

[0257] The second negative electrode active material includes graphite particles, and the volume average particle size Dv50 of the graphite particles is from 9.5 μm to 18.5 μm, and can be from 9.5 μm to 14.6 μm. Optionally, the second negative electrode active material includes natural graphite.

[0258] In some embodiments, the specific surface area of the negative electrode active material is 0.5 m 2 / g - 3 m 2 / g, and can be 0.6 m 2 / g - 1.2 m 2 / g. Exemplarily, the specific surface area of the negative electrode active material is 0.5 m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1.0 m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g, 2.0 m 2 / g, 2.1 m 2 / g, 2.2 m 2 / g, 2.3 m 2 / g, 2.4 m 2 / g, 2.5 m 2 / g, 2.6 m 2 / g, 2.7 m 2 / g, 2.8 m 2 / g, 2.9 m 2 / g, 3.0 m 2 / g or a range composed of any two of the above values.

[0259] The specific surface area of the material has the meaning well-known in the art and can be detected by devices and methods well-known in the art. For example, it can be detected according to the test standard GB / T 19587-2017. Taking the negative electrode active material as a sample, the specific surface area is tested by a Tri-Star 3020 specific surface area and pore size analyzer of Micromeritics Corporation in the United States.

[0260] In the embodiments of the present application, the specific surface area of the negative electrode active material is limited to be greater than or equal to 0.5 m 2 / g, which can improve the fast charging ability of the battery cell 10; the specific surface area of the negative electrode active material is limited to be less than or equal to 3 m 2 / g, which can reduce the side reactions during the storage of the battery cell 10, slow down the swelling of the negative electrode sheet, and reduce the swelling pressure.

[0261] In some embodiments, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 ; it can be optionally 2.55 g / cm 3 -2.70 g / cm 3 . Exemplarily, when the battery cell 10 is at 100% state of charge SOC, the compaction density of the positive electrode film layer 1112 is 2.50 g / cm 3 , 2.52 g / cm 3 , 2.55 g / cm 3 , 2.56 g / cm 3 , 2.57 g / cm 3 , 2.58 g / cm 3 , 2.60 g / cm 3 , 2.62 g / cm 3 , 2.65 g / cm 3 , 2.68 g / cm 3 , 2.30 g / cm 3 , 2.32 g / cm 3 , 2.75 g / cm 3 , 2.78 g / cm 3 , 2.80 g / cm 3 or a range composed of any two of the above values.

[0262] When the compaction density of the positive electrode film layer 1112 is within the above range, it is beneficial to improve the energy density of the battery cell 10; and since the positive electrode active materials in the positive electrode film layer 1112 are stacked relatively tightly and the contact resistance between particles is small, the resistance of the positive electrode sheet 111 can be further reduced, thereby reducing heat generation during rapid charging.

[0263] In the embodiments of the present application, the compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell has the meaning well known in the art, that is, the positive electrode sheet 111 is disassembled from the battery cell at 100% SOC, and the compaction density of the positive electrode film layer 1112 is measured. Exemplarily, the test method for the compaction density of the positive electrode film layer 1112 can be the same as that for the compaction density of the negative electrode film layer 1122.

[0264] In some embodiments, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 ; optionally 240 mg / 1540 mm 2 to 330 mg / 1540 mm 2 . Exemplarily, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540.25 mm 2 、210 mg / 1540.25 mm 2 、220 mg / 1540.25 mm 2 、230 mg / 1540.25 mm 2 、240 mg / 1540.25 mm 2 、250 mg / 1540.25 mm 2 、260 mg / 1540.25 mm 2 、270 mg / 1540.25 mm 2 、280 mg / 1540.25 mm 2 、290 mg / 1540.25 mm 2 、300 mg / 1540.25 mm 2 、310 mg / 1540.25 mm 2 、320 mg / 1540.25 mm 2 、330 mg / 1540.25 mm 2 、340 mg / 1540.25 mm 2 、350 mg / 1540.25 mm 2 、360 mg / 1540.25 mm 2 、370 mg / 1540.25 mm 2 or a range composed of any two of the above values.

[0265] In the embodiments of the present application, the single-sided coating weight of the positive electrode film layer 1112 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. The detection method is the same as the single-sided coating weight test method of the negative electrode film layer 1122 described above.

[0266] Set the single-sided coating weight of the positive electrode film layer 1112 at 200 mg / 1540 mm 2 -370 mg / 1540 / mm 2 , which can limit the heat generation per unit area of the positive electrode sheet 111 and can take into account the improvement of the energy density and charging rate performance of the battery cell 10.

[0267] 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 any range composed of any two of the above values.

[0268] In the embodiments of the present application, the porosity of the positive electrode sheet 111 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. The detection method is the same as the porosity test method of the negative electrode sheet 112.

[0269] When the porosity of the positive electrode sheet 111 is greater than or equal to 25%, it can provide space for the impurities generated by side reactions in the positive electrode sheet 111, reduce the expansion pressure of the battery cell, reduce the deformation of the battery cell 10, improve the cycling performance of the battery cell 10, and reduce the risk of connection failure between the battery cell and the current collecting component. When the porosity of the positive electrode sheet 111 is less than or equal to 32%, it can take into account the energy density of the battery cell 10 to a certain extent.

[0270] In some embodiments, the thickness of the positive electrode sheet 111 can be 0.13 mm - 0.2 mm. As an example, the thickness of the positive electrode sheet 111 can be 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm or any range composed of any two of the above values.

[0271] In the embodiments of the present application, the thickness of the positive electrode sheet 111 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. For example, a micrometer is used to measure the thickness of the positive electrode sheet 111.

[0272] 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.

[0273] In some embodiments, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is from 0.05 to 0.3. Exemplarily, in the embodiments of the present application, the thickness of the positive electrode film layer 1112 is the thickness of the positive electrode film layer 1112 on one side of the positive electrode current collector 1111.

[0274] Exemplarily, the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3 or a range composed of any two of the above values.

[0275] Limiting the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be greater than or equal to 0.05 can improve the current-carrying 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 ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be less than or equal to 0.3 can reduce the loss of the capacity of the positive electrode sheet 111. In the embodiments of the present application, limiting the ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 to be from 0.05 to 0.3 can balance the fast charging ability and energy density of the battery cell 10 to a certain extent.

[0276] The thickness of the positive electrode film layer and the thickness of the positive electrode current collector have meanings well-known in the art, and can be detected by equipment and methods well-known in the art. For example, the thickness of the positive electrode sheet is measured with 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 with 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.

[0277] In some embodiments, the thickness of the positive electrode current collector 1111 is from 10 μm to 15 μm, and can be optionally from 12 μm to 15 μm. Exemplarily, 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 composed of any two of the above values. When the thickness of the positive electrode current collector 1111 is within the above range, the current-carrying capacity of the positive electrode current collector 1111 is relatively excellent, and the battery cell 10 can have a relatively high energy density.

[0278] In some embodiments, a part of the positive electrode current collector 1111 is not covered by the positive electrode film layer 1112; the part of the positive electrode current collector 1111 not covered by the positive electrode film layer 1112 can be used to form the positive electrode tab 11b.

[0279] In some embodiments, the positive electrode active material includes a lithium-containing phosphate having an olivine structure or a modified material thereof.

[0280] The lithium-containing phosphate having an olivine structure or a modified material thereof may be a lithium-containing phosphate having an olivine structure or a material obtained by coating and modifying it. For example, the lithium-containing phosphate having an olivine structure includes phosphate particles and an ion-conducting layer, and the ion-conducting layer is coated on the surface of the phosphate particles, and the ion-conducting layer contains one or more elements among C, Fe, Ti, Zr, Hf, Ge, and Sn.

[0281] In some embodiments, the mass ratio of the lithium-containing phosphate having an olivine structure or a modified material thereof in the positive electrode active material may be greater than or equal to 80% and less than or equal to 100%. It can be considered that the positive electrode active material of the present application is a lithium-containing phosphate having an olivine structure or a modified material system thereof. When the mass ratio of the lithium-containing phosphate having an olivine structure or a modified material thereof is less than 100%, the positive electrode active material may further include a commonly used positive electrode active material, such as at least one of lithium-containing transition metal oxides. Examples of the 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.

[0282] Optionally, the mass ratio of the lithium-containing phosphate having an olivine structure or a modified material thereof in the positive electrode active material is 100%.

[0283] 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.

[0284] Exemplarily, Dv50 of the positive electrode active material may be 1 µm, 1.1 µm, 1.15 µm, 1.2 µm, 1.25 µm, 1.3 µm, 1.35 µm, 1.4 µm, 1.45 µm, 1.5 µm, 1.55 µm, 1.6 µm, 1.65 µm, 1.7 µm, 1.75 µm, 1.8 µm, 1.85 µm, 1.9 µm, 1.95 µm, 2 µm, or a range composed of any two of the above values.

[0285] Exemplarily, Dv10 of the positive electrode active material may be 0.4 µm, 0.45 µm, 0.5 µm, 0.55 µm, 0.6 µm, 0.65 µm, 0.7 µm, or a range composed of any two of the above values.

[0286] The particle size of the positive electrode active material is relatively small, the lithium deintercalation / insertion path of lithium ions in the positive electrode active material is short, and the heat generation is less; moreover, the particle size of the above-mentioned positive electrode active material is not too small, which can reduce agglomeration during the processing and preparation process, so that the performance of the positive electrode active material is stable.

[0287] The volume average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, and the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% in the volume distribution. It can be detected by using equipment and methods well-known in the art. For example, taking the positive electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 and Dv10 of the particles are tested by a Mastersizer 2000E laser particle size analyzer.

[0288] In some embodiments, the battery cell 10 includes an electrolyte accommodated in the housing 12. During the charge and discharge process of the battery cell 10, active ions are embedded and deintercalated back and forth between the positive electrode sheet 111 and the negative electrode sheet 112, and the electrolyte plays a role in conducting active ions between the positive electrode sheet 111 and the negative electrode sheet 112.

[0289] In some embodiments, the conductivity of the electrolyte at room temperature is 13 mS / cm to 20 mS / cm, and can be optionally 15 mS / cm to 20 mS / cm. Exemplarily, the conductivity of the electrolyte at room temperature is 13 mS / cm, 13.5 mS / cm, 14 mS / cm, 14.5 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 16.5 mS / cm, 17 mS / cm, 17.5 mS / cm, 18 mS / cm, 18.5 mS / cm, 19 mS / cm, 19.5 mS / cm, 20 mS / cm or the range composed of any two of the above values.

[0290] As an example, the room temperature can be 25 °C.

[0291] When the conductivity of the electrolyte is within the above range, the migration rate of ions in the electrolyte is relatively high, thereby further reducing the internal resistance of the battery cell 10, reducing heat generation, and improving the fast charging performance of the battery cell 10.

[0292] The conductivity of the electrolyte is the ionic conductivity, and it can be detected by using equipment and methods well-known in the art. For example, it is tested with reference to the industry standard HG-T 4067-2015.

[0293] In some embodiments, the density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

[0294] Exemplarily, the density ρ of the electrolyte is 1.05 g / mL, 1.10 g / mL, 1.15 g / mL, 1.2 g / mL, 1.25 g / mL, 1.3 g / mL, 1.35 g / mL, or a range composed of any two of the above values.

[0295] When the density ρ of the electrolyte is within the above range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery cell 10, thereby reducing heat generation and improving the fast charging performance of the battery cell 10.

[0296] In the embodiments of the present application, the density of the electrolyte has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. For example, it can be tested with reference to GB / T 2013-2010.

[0297] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes one or more of carbonate solvents and carboxylate solvents.

[0298] In some embodiments, the carboxylate solvent includes a chain carboxylate solvent, and the mass content of the chain carboxylate solvent in the organic solvent is 5% to 75%. Exemplarily, the mass content of the chain carboxylate solvent is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or a range composed of any two of the above values. When the mass content of the chain carboxylate solvent is within the above range, the viscosity of the electrolyte system is relatively small, which is beneficial to the migration of lithium ions.

[0299] In some embodiments, the mass content of the chain carboxylate solvent in the organic solvent is 30% to 70%.

[0300] In some embodiments, the carboxylate includes R 1 -COO-R 2 ,R 1 and R 2 respectively and independently include an alkyl group with 1-5 carbon atoms or a halogenated alkyl group with 1-5 carbon atoms. The chain carboxylate solvent has a relatively high conductivity, which is beneficial to improving the fast charging ability of the battery cell 10.

[0301] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0302] Further optionally, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0303] The above-mentioned carbonate solvents and chain carboxylic acid ester solvents are used in combination, which improves the conductivity of the electrolyte and is beneficial to the migration of lithium ions.

[0304] Further optionally, the mass content of the carbonate solvent in the organic solvent is 5% to 95%, optionally 25% to 60%, and optionally 30% to 45%. Exemplarily, the mass content of the carbonate solvent in the organic solvent is 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60% or the range composed of any two of the above values. The carbonate solvent with the above mass content can further improve the conductivity of the electrolyte and is beneficial to the migration of lithium ions.

[0305] Exemplarily, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the mass content of the carbonate solvent is 25% to 60%.

[0306] The organic solvent combination can improve the conductivity of the electrolyte and reduce the viscosity, thereby improving the fast charging performance of Battery 2.

[0307] In some embodiments, the electrolyte includes a lithium salt. The lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate LiPF6. The above lithium salts are easy to dissociate, which is beneficial to the rapid migration of lithium ions; and the electrolyte system is relatively stable and not easy to decompose, which can improve the cycle performance of Battery Cell 10.

[0308] Optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0309] In some embodiments, the lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF 6 , the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is 0.5 mol / L to 1.0 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.4 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is 0.7 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6 is 0.5 mol / L. Exemplarily, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.2 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF 6The molar concentration is 0.8 mol / L.

[0310] Optionally, the molar concentration ratio of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate LiPF 6 is (2 to 5):10. Exemplarily, the molar concentration ratio of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate LiPF 6 is 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10, 5:10 or a range composed of any two of the above values.

[0311] In some embodiments, the dimension of the electrode assembly 11 in the thickness direction X is T, the thickness of the single-layer negative electrode sheet 112 is T1, and the number of layers of the negative electrode sheets 112 stacked in the thickness direction X is N. T, T1, and N satisfy: 0.3 ≤ (N×T1) / T ≤ 0.5.

[0312] At least one of the negative electrode sheets 112 includes a flat layer 112a perpendicular to the thickness direction X, and the number of layers of the flat layer 112a in the electrode assembly 11 is N.

[0313] Exemplarily, the battery cell 10 is disassembled at 0% state of charge, and the electrode assembly 11 is taken out; a micrometer is used to measure T and T1.

[0314] Exemplarily, the electrode assembly 11 is a wound structure, and the negative electrode sheet 112 includes N flat layers 112a; alternatively, the electrode assembly 11 is a stacked structure, the electrode assembly 11 includes N negative electrode sheets 112, and each negative electrode sheet 112 includes a flat layer 112a.

[0315] During the cycling of the battery cell 10, the thickness of the negative electrode sheet 112 increases due to irreversible side reactions, thereby causing the battery cell 10 to expand; limiting (N×T1) / T to 0.3 - 0.5 can reduce the expansion of the battery cell 10 and reduce the risk of connection failure between the battery cell 10 and the current collecting component 30.

[0316] In some embodiments, the limiting beam 21 is an integrally formed structure, which can reduce the connection weak points of the limiting beam 21 and is beneficial to improving the structural strength and stiffness of the limiting beam 21. Alternatively, the limiting beam 21 can also be composed of multiple components spliced together. For example, the limiting beam 21 is formed by welding multiple sheet metal parts.

[0317] In some embodiments, the limiting beam 21 is a profile beam.

[0318] The limiting beam 21 can be a hollow beam structure formed by a plate or a rod through stamping / extrusion or metal casting. The wall thickness of the limiting beam 21 can be 1mm-8mm according to actual needs, and 3mm-5mm is more common. With this wall thickness, the limiting beam 21 has a good cost performance, and can have a light weight and good structural strength, which can effectively suppress the expansion deformation of the battery cell 10 during the cycle.

[0319] The limiting beam 21 can be made of, but is not limited to, steel, iron, aluminum, and aluminum alloy.

[0320] In some embodiments, the box 20 includes a frame 22 and a support beam 23. The frame 22 defines a storage space, and the limiting beam 21 and multiple battery cells 10 are arranged in the storage space. The support beam 23 is arranged on the side of the limiting beam 21 away from the multiple battery cells 10 and connects the frame 22 and the limiting beam 21.

[0321] Optionally, the frame 22 may be a rectangular frame.

[0322] The number of the supporting beam 23 may be one or more.

[0323] For two adjacent limiting beams 21 , one limiting beam 21 may be connected to the supporting beam 23 , or both limiting beams 21 may be connected to the supporting beam 23 .

[0324] During the cycle of the battery 2, the limiting beam 21 is used to resist the expansion force of the battery cell 10 during the cycle. The frame 22 can support the limiting beam 21 through the support beam 23, thereby providing effective support for the limiting beam 21, reducing the deformation of the limiting beam 21, and further providing constraints to the battery cell 10, reducing the expansion of the battery cell 10, and improving the cycle life of the battery cell 10.

[0325] By providing the supporting force connecting the frame 22 and the limiting beam 21 , the overall structural strength and rigidity of the box body 20 can be improved, and the risk of cracking of the box body 20 can be reduced.

[0326] In some embodiments, the frame 22 includes a plurality of side beams, which are sequentially arranged and connected to form an annular frame 22 .

[0327] In some embodiments, the support beam 23 extends along the thickness direction X. Optionally, the cross section of the support beam 23 perpendicular to the thickness direction X may be rectangular, trapezoidal, elliptical, circular, L-shaped or other shapes.

[0328] In some embodiments, the support beam 23 is a plate or hollow beam structure. The support beam 23 can be made of steel, aluminum or aluminum alloy.

[0329] In some embodiments, the support beam 23 and the housing 22 can be fixedly connected by welding, bolt connection, snap connection or the like.

[0330] In some embodiments, the limiting beam 21 extends in a direction perpendicular to the thickness direction X. The housing 20 includes a plurality of support beams 23 arranged at intervals in the width direction Y of the limiting beam 21. The plurality of support beams 23 can increase the binding force received by the limiting beam 21, improve the uniformity of the force on different regions of the limiting beam 21, reduce the deformation of the limiting beam 21 during the cycling of the battery cell 10, and improve the cycling performance of the battery 2.

[0331] In some embodiments, the housing 20 further includes a carrier plate 24. The plurality of battery cells 10 and the limiting beam 21 are located on the same side of the carrier plate 24 and fixed to the carrier plate 24. Exemplarily, the carrier plate 24 and the plurality of battery cells 10 are arranged along the height direction Z of the battery cell 10.

[0332] In some embodiments, the housing 20 further includes a cover plate (not shown). The cover plate is disposed opposite to the carrier plate 24 in the height direction Z and fixed to the housing 22. The battery cell and the limiting beam are located between the cover plate and the carrier plate.

[0333] In some examples, the carrier plate 24 is located above the battery cell and the battery cell is inverted; alternatively, in some other examples, the carrier plate 24 is located below the battery cell and the battery cell is upright.

[0334] Figure 13 A top view schematic diagram of the battery provided in some other embodiments of the present application; Figure 14 is Figure 13 An enlarged schematic diagram at the square box; Figure 15 is Figure 14 A structural schematic diagram of the second current collecting component in.

[0335] Please refer to Figure 6 and Figures 13 - 15 , in some embodiments, the battery 2 further includes at least one second current collecting component 30b. The second current collecting component 30b is a single-layer structure and electrically connects at least two battery cells 10. The thickness of the second current collecting component 30b is greater than the thickness of the first current collecting layer 31, and the thickness of the second current collecting component 30b is greater than the thickness of the second current collecting layer 32.

[0336] Exemplarily. Among the plurality of current collecting components 30, a part of the current collecting components 30 are first current collecting components 30a, and another part of the current collecting components 30 are second current collecting components 30b.

[0337] In battery 2, the swelling amounts of the battery cells 10 at different positions may vary. For the battery cells 10 with a smaller swelling amount, a second busbar component 30b with a single-layer structure can be adopted; compared with the first busbar component 30a, the second busbar component 30b has a simple structure, is easy to manufacture, and can save costs. The thickness of the second busbar component 30b is greater than the thickness of the first busbar layer 31 and the thickness of the second busbar layer 32, and its current-carrying capacity can meet the requirements.

[0338] In some embodiments, the sum of the thickness of the first busbar layer 31 and the thickness of the second busbar layer 32 is equal to the thickness of the second busbar component 30b. The embodiments of the present application can reduce the difference in the current-carrying capacity between the first busbar component 30a and the second busbar component 30b and improve the current consistency.

[0339] In some embodiments, the second busbar component 30b connects at least two battery cells 10 arranged along the thickness direction X.

[0340] In some embodiments, among the multiple battery cells 10, the outermost battery cell 10 along the thickness direction X is connected to the first busbar component 30a.

[0341] During the charging process, the swelling of the multiple battery cells 10 may be superimposed in the thickness direction X, which causes a relatively large displacement of the outermost battery cell 10 in the thickness direction X; adopting the first busbar component 30a with a double-layer structure to connect the outermost battery cell 10 can reduce the risk of connection failure between the first busbar component 30a and the battery cell 10.

[0342] Exemplarily, the outermost battery cell 10 along the thickness direction X is connected to the first busbar layer 31.

[0343] In some embodiments, the battery cell 10 adjacent to the limiting beam 21 can be connected to the first busbar component 30a.

[0344] In some embodiments, the multiple busbar components 30 further include a third busbar component 30c, and the third busbar component 30c can connect two adjacent battery cells 10 along the width direction Y.

[0345] In some embodiments, in an external environment of 25°C to 35°C, the charging time of the battery cell 10 from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes. Optionally, in an external environment of 25°C to 35°C, the charging time of the battery cell 10 from 10% SOC to 80% SOC can be 5 min to 10.5 min. Exemplarily, the charging time of the battery cell 10 from 10% state of charge to 80% state of charge is 10.5 min, 10 min, 9.5 min, 9 min, 8.5 min, 8 min, 7.5 min, 7 min, 6.5 min, 6 min, 5.5 min, 5 min or a range composed of any two of the above values.

[0346] The battery cell 10 of the embodiments of the present application has a fast charging ability and can save charging time.

[0347] In some embodiments, the charging step of the battery 2 or any battery cell 10 constituting the battery 2 from 10% to 80% can be carried out in the following manner: Charge from 10% SOC to 15% SOC at a constant current of 5.0C; Charge from 15% SOC to 20% SOC at a constant current of 5.0C; Charge from 20% SOC to 25% SOC at a constant current of 5.0C; Charge from 25% SOC to 30% SOC at a constant current of 5.0C; Charge from 30% SOC to 35% SOC at a constant current of 5.0C; Charge from 35% SOC to 40% SOC at a constant current of 5.0C; Charge from 40% SOC to 45% SOC at a constant current of 4.6C; Charge from 45% SOC to 50% SOC at a constant current of 4.3C; Charge from 50% SOC to 55% SOC at a constant current of 4.0C; Charge from 55% SOC to 60% SOC at a constant current of 3.7C; Charge from 60% SOC to 65% SOC at a constant current of 3.4C; Charge from 65% SOC to 70% SOC at a constant current of 3.1C; Charge from 70% SOC to 75% SOC at a constant current of 2.9C; Charge from 75% SOC to 80% SOC at a constant current of 2.7C.

[0348] As an example, the above charging strategy is carried out in an environment of 30°C.

[0349] In some embodiments, the charging step of the battery cell 10 from 0% SOC to 10% SOC can be carried out as follows: charge at a constant current of 5.0C from 0% SOC to 10% SOC.

[0350] In some embodiments, the charging step of the battery cell 10 from 80% SOC to 98% SOC can be carried out as follows: Charge at a constant current of 1.8C from 80% SOC to 85% SOC; Charge at a constant current of 1.3C from 85% SOC to 90% SOC; Charge at a constant current of 0.7C from 90% SOC to 95% SOC; Charge at a constant current of 0.33C from 95% SOC to 98% SOC.

[0351] In some embodiments, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be carried out as follows: charge at a constant current of 0.01C, 0.05C, 0.1C or 0.3C from 98% SOC to 100% SOC. Optionally, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be carried out as follows: charge at a constant current of 0.01C, 0.05C or 0.1C from 98% SOC to 100% SOC.

[0352] In some embodiments, during the process of charging the battery cell 10 from 10% SOC to 80% SOC, the charging current can be 2C - 6C, and optionally 2.7C - 5C. During the charging process of the battery cell 10, the charging current can vary according to the SOC of the battery cell 10.

[0353] In some embodiments, the battery cell 10 is a lithium - ion battery cell. After cycling the battery cell 10 20 times according to the charging strategy and the discharging strategy, disassemble the negative electrode sheet of the battery cell 10, and observe and measure the lithium - plating area of the negative electrode sheet. The ratio of the area of the lithium - plating region to the total area of the negative electrode sheet is less than 2%.

[0354] As an example, the discharging strategy is to discharge at a constant current of 0.33C to 2.0V.

[0355] As an example, the charging strategy can be: Charge at a constant current of 5.0C from 0% SOC to 5% SOC; Charge at a constant current of 5.0C from 5% SOC to 10% SOC; Charge at a constant current of 5.0C from 10% SOC to 15% SOC; Charge at a constant current of 5.0C from 15% SOC to 20% SOC; Charge from 20% SOC to 25% SOC at a constant current of 5.0C; Charge from 25% SOC to 30% SOC at a constant current of 5.0C; Charge from 30% SOC to 35% SOC at a constant current of 5.0C; Charge from 35% SOC to 40% SOC at a constant current of 5.0C; Charge from 40% SOC to 45% SOC at a constant current of 4.6C; Charge from 45% SOC to 50% SOC at a constant current of 4.3C; Charge from 50% SOC to 55% SOC at a constant current of 4.0C; Charge from 55% SOC to 60% SOC at a constant current of 3.7C; Charge from 60% SOC to 65% SOC at a constant current of 3.4C; Charge from 65% SOC to 70% SOC at a constant current of 3.1C; Charge from 70% SOC to 75% SOC at a constant current of 2.9C; Charge from 75% SOC to 80% SOC at a constant current of 2.7C; Charge from 80% SOC to 85% SOC at a constant current of 1.8C; Charge from 85% SOC to 90% SOC at a constant current of 1.3C; Charge from 90% SOC to 95% SOC at a constant current of 0.7C; Charge from 95% SOC to 98% SOC at a constant current of 0.33C; Charge from 98% SOC to 100% SOC at a constant current of 0.1C.

[0356] The battery cell 10 of the embodiment of the present application can charge from 10% SOC to 80% SOC within 10.5 minutes without lithium plating or with slight lithium plating, and has good fast charging ability. Exemplarily, when the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 0.05%, it can be considered that there is no lithium plating. When the ratio of the area of the lithium plating region to the total area of the negative electrode sheet is less than 2% and greater than or equal to 0.05%, it can be considered as slight lithium plating.

[0357] According to some embodiments of the present application, the present application further provides an electrical device, including the battery 2 of any one of the above embodiments, and the battery 2 is used to provide electrical energy for the electrical device. The electrical device can be any of the foregoing devices or systems that apply the battery 2.

[0358] Referring to Figures 2 to 12 , the embodiment of the present application provides a battery 2, which includes a plurality of battery cells 10, a box body 20, and a plurality of busbar components 30. The plurality of battery cells 10 are accommodated in the box body 20.

[0359] The battery cell 10 includes a housing 12 and an electrode assembly 11 accommodated in the housing 12. The expansion pressure of the battery cell in the thickness direction X is 0.5 MPa - 2.4 MPa.

[0360] The electrode assembly 11 includes a positive electrode sheet 111, a negative electrode sheet 112, and a separator 113. The separator 113 separates the positive electrode sheet 111 and the negative electrode sheet 112. Optionally, the positive electrode sheet 111, the negative electrode sheet 112, and the separator 113 are wound.

[0361] The negative electrode sheet 112 includes a negative electrode current collector 1121 and a negative electrode film layer 1122 provided on at least one side of the negative electrode current collector 1121. The negative electrode film layer 1122 includes a negative electrode active material. The porosity of the negative electrode sheet 112 is 27% - 40%. The compaction density of the negative electrode film layer 1122 at 100% SOC of the battery cell is 1.15 g / cm 3 to 1.36 g / cm 3 .

[0362] The negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222. The second negative electrode film layer 11222 is provided between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material provided in the first negative electrode film layer 11221 and a second negative electrode active material provided in the second negative electrode film layer 11222. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials. The volume average particle diameter Dv50 of the first negative electrode active material is less than or equal to the volume average particle diameter Dv50 of the second negative electrode active material.

[0363] The positive electrode sheet 111 includes a positive electrode current collector 1111 and a positive electrode film layer 1112 provided on at least one side of the positive electrode current collector 1111. The compaction density of the positive electrode film layer 1112 at 100% SOC of the battery cell is 2.50 g / cm 3 to 2.80 g / cm 3 . The porosity of the positive electrode sheet 111 is 25% - 32%. The ratio of the thickness of the positive electrode current collector 1111 to the thickness of the positive electrode film layer 1112 is 0.05 to 0.3. The positive electrode active material includes a lithium-containing phosphate in an olivine structure or a modified material thereof. The volume average particle diameter of the positive electrode active material satisfies 1 µm ≤ Dv50 ≤ 2 µm, 0.4 µm ≤ Dv10 ≤ 0.7 µm.

[0364] The box body 20 includes two limiting beams 21, and the two limiting beams 21 are arranged at intervals along the thickness direction X of the battery cell 10. A plurality of battery cells 10 are arranged in an array and constitute a plurality of battery cell columns 100, and the plurality of battery cell columns 100 are arranged along the width direction Y of the limiting beams 21, and each battery cell column 100 includes at least two battery cells 10 arranged along the thickness direction X of the battery cell 10. The plurality of battery cells 10 are arranged between the two limiting beams 21.

[0365] The box body 20 includes a frame 22 and a support beam 23. The frame 22 defines a storage space, and the limit beam 21 and multiple battery cells 10 are arranged in the storage space. The support beam 23 is arranged on the side of the limit beam 21 away from the multiple battery cells 10 and connects the frame 22 and the limit beam 21. The restraint member 40 connects adjacent limit beams 21 and is bonded to the battery cell 10.

[0366] The plurality of busbars 30 electrically connect the plurality of battery cells 10. The plurality of busbars 30 include at least one first busbar 30a including stacked and connected first and second busbar layers 31 and 32. The first busbar layer 31 connects at least two battery cells 10 arranged in the thickness direction X.

[0367] Example The following examples more specifically describe the contents disclosed in the embodiments of the present application, and these examples are only for illustrative purposes, because it is obvious to those skilled in the art that various modifications and changes are made within the scope of the disclosure of the embodiments of the present application. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0368] Example 1 1. Preparation of positive electrode sheet The positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on both sides of the positive electrode current collector. The positive electrode current collector is an aluminum foil with a thickness of 15 μm.

[0369] The positive electrode film layer includes a film layer formed by uniformly coating the positive electrode slurry (the solvent is N-methylpyrrolidone NMP) on the surface of the positive electrode conductive layer, drying, and cold pressing. The positive electrode film layer includes a positive electrode active material, a binder polyvinylidene fluoride (PVDF), and a conductive agent acetylene black in a weight ratio of 97:2:1.

[0370] The positive electrode active material includes lithium iron phosphate and an ion-conducting layer, the ion-conducting layer is coated on the surface of the lithium iron phosphate, and the ion-conducting layer includes lithium titanium iron phosphate Li 2 FeTi(PO 4 )3 and amorphous carbon. The Dv50 of the positive electrode active material is 1.6 μm, and the Dv10 is 0.64 μm.

[0371] The single-sided coating weight of the positive electrode film layer is 0.21 g / 1540.25 mm 2 , and the compaction density of the positive electrode film layer after cold pressing is 2.6 g / cm 3 .

[0372] 2. Preparation of the negative electrode sheet The negative electrode sheet includes a negative electrode current collector and negative electrode film layers provided on both sides of the negative electrode current collector. The negative electrode current collector is a copper foil with a thickness of 6 μm.

[0373] The negative electrode film layer is formed by uniformly coating the surface of the negative electrode conductive layer with a negative electrode slurry (the solvent is deionized water), followed by drying and cold pressing.

[0374] The single-sided coating weight of the negative electrode film layer is 0.096 g / 1540.25 mm 2 , and the compaction density of the negative electrode film layer after cold pressing is 1.6 g / cm 3 .

[0375] 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 is located between the first negative electrode film layer and the negative electrode current collector.

[0376] The second negative electrode film layer includes graphite particles, conductive agent acetylene black, second lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-2-hydroxyethyl acrylate copolymer, where the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose in a mass ratio of 96.5:0.5:0.5:1.5:1. The mass content of lithium element in the second lithium-containing binder is 4.8%. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include artificial graphite and a carbon coating layer. The carbon coating layer covers the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0377] The first negative electrode film layer includes graphite particles, conductive agent acetylene black, first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-2-hydroxyethyl acrylate copolymer, where the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose in a mass ratio of 97.5:0.5:0.5:0.5:1. The mass content of lithium element in the first lithium-containing binder is 4.8%. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include artificial graphite and a carbon coating layer. The carbon coating layer covers the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0378] 3. Separator The separator includes a base film, which is a 7-μm polyethylene film layer with a porosity of 42%.

[0379] 4. Preparation of electrolyte The electrolyte includes an organic solvent, a lithium salt, and an additive.

[0380] The organic solvent includes 60% chain carboxylic ester solvent (ethyl acetate) and 40% carbonate solvent (30% ethylene carbonate EC, and the rest is dimethyl carbonate). The mass content of each component in the organic solvent is calculated based on the mass of the organic solvent.

[0381] Based on the mass of the electrolyte, the mass content of the additive is 6.5%, which includes vinylene carbonate VC, fluoroethylene carbonate FEC, ethylene sulfite ES, and lithium difluorooxalate borate LiDFOB with a mass ratio of 5:0.5:0.5:0.5.

[0382] The lithium salt includes 1 mol / L lithium hexafluorophosphate LiPF 6 .

[0383] The conductivity of the electrolyte at room temperature is 16.4 mS / cm.

[0384] 5. Preparation of battery cell Stack the above positive electrode plate, separator, and negative electrode plate in sequence, with the separator placed between the positive electrode plate and the negative electrode plate to play an isolation role, obtaining an electrode assembly. Place the electrode assembly in a casing, inject the electrolyte after drying, and go through processes such as vacuum packaging, standing, forming, and shaping to obtain a battery cell.

[0385] 6. Preparation of battery Install the prepared multiple battery cells into a box, then weld multiple busbar components to the electrode terminals of the multiple battery cells, and install high and low voltage wire harnesses to obtain a battery.

[0386] Among them, the busbar component can be Figure 6 the first busbar component shown. The first busbar component has a double-layer structure. The thickness Th of the single-layer structure of the first busbar component is 1.5 mm, that is, the thickness of the first busbar layer is 1.5 mm, and the thickness of the second busbar layer is 1.5 mm.

[0387] Example 2 Prepare battery cells and batteries using a method similar to that in Example 1. The difference from Example 1 is that the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing are adjusted.

[0388] Example 3 The battery single cells and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing were adjusted.

[0389] Example 4 The battery single cells and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0390] Example 5 The battery single cells and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0391] Example 6 The battery single cells and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0392] Example 7 The battery single cells and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0393] Comparative Example 1 The battery single cells and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing were adjusted.

[0394] Comparative Example 2 The battery single cells and batteries were prepared by a method similar to that of Example 1. Different from Example 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first current collecting member were adjusted.

[0395] Comparative Example 3 The battery single cell and the battery were prepared by a method similar to that of Example 1. The difference from Example 1 is that the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first current collecting component were adjusted.

[0396] Comparative Example 4 The battery single cell and the battery were prepared by a method similar to that of Example 1. The difference from Example 1 is that the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, the compaction density of the negative electrode film layer after cold pressing, and the thickness Th of the single-layer structure of the first current collecting component were adjusted.

[0397] Performance Test 1. Test the expansion pressure of the battery single cell: In an ambient temperature of 45°C, the battery single cell prepared above was discharged at a constant current discharge rate of 1C to 2.0V; The battery single cell was clamped between two clamping plates. Among them, the two clamping plates were respectively located on both sides of the battery single cell in the thickness direction and covered the large surface; In an ambient temperature of 45°C, the battery single cell was charged at a constant current charge rate of 0.8C to 3.8V, and the pressure exerted by the battery single cell on the clamping plate was detected and recorded; According to the above charging strategy and discharging strategy, the battery single cell was cycled for charge and discharge until the battery single cell decayed to 70% SOH (the discharge capacity of the battery single cell decayed to 70% of the nominal capacity of the battery single cell), and the maximum pressure exerted by the battery single cell on the clamping plate was recorded; Calculate the expansion pressure Q of the battery single cell in the thickness direction as: maximum pressure / large surface area.

[0398] 2. Volume energy density test: The first-week discharge energy was tested according to the following steps: At 25°C, the battery single cell prepared above was charged at a constant current of 0.33C to 3.8V, and then discharged at a constant current of 0.33C to 2.0V, and the discharge energy A0 at this time was recorded, unit: Wh.

[0399] Volume of the battery single cell: Use a caliper to measure the length, width, and height of the battery single cell (generally calculated based on the outer shell size of the battery single cell, excluding the height of the electrode terminal and excluding the insulating film outside the outer shell), and calculate the volume V0 of the single-cell battery, unit L.

[0400] The volume energy density VED of the battery single cell = A0 / V0, unit Wh / L.

[0401] 3. Cycle performance test one: At an ambient temperature of 45°C, discharge the battery prepared above, and discharge the battery cell at a constant current discharge rate of 1C to 2.0V; At an ambient temperature of 45°C, charge the battery prepared above, and charge the battery cell at a constant current charge rate of 0.8C to 3.8V; Perform cyclic charge and discharge on the battery according to the above charge strategy and discharge strategy until the battery decays to 70% SOH (discharge capacity of the battery / nominal capacity of the battery = 70%); During the cycling process, detect the maximum temperature of the end cap of the outer shell of the battery cell, and observe whether the welding joint between the first busbar component and the electrode terminal is cracked.

[0402] 4. Cycling performance test two: At an ambient temperature of 30°C, discharge the battery prepared above, and discharge the battery cell at 0.33C to 2.0V; At an ambient temperature of 30°C, charge the battery using the following charge strategy: Charge at a constant current of 5.0C from 0% SOC to 5% SOC; Charge at a constant current of 5.0C from 5% SOC to 10% SOC; Charge at a constant current of 5.0C from 10% SOC to 15% SOC; Charge at a constant current of 5.0C from 15% SOC to 20% SOC; Charge at a constant current of 5.0C from 20% SOC to 25% SOC; Charge at a constant current of 5.0C from 25% SOC to 30% SOC; Charge at a constant current of 5.0C from 30% SOC to 35% SOC; Charge at a constant current of 5.0C from 35% SOC to 40% SOC; Charge at a constant current of 4.6C from 40% SOC to 45% SOC; Charge at a constant current of 4.3C from 45% SOC to 50% SOC; Charge at a constant current of 4.0C from 50% SOC to 55% SOC; Charge at a constant current of 3.7C from 55% SOC to 60% SOC; Charge at a constant current of 3.4C from 60% SOC to 65% SOC; Charge at a constant current of 3.1C from 65% SOC to 70% SOC; Charge at a constant current of 2.9C from 70% SOC to 75% SOC; Charge at a constant current of 2.7C from 75% SOC to 80% SOC; Charge at a constant current of 1.8C from 80% SOC to 85% SOC; Charge from 85% SOC to 90% SOC at a constant current of 1.3C; Charge from 90% SOC to 95% SOC at a constant current of 0.7C; Charge from 95% SOC to 98% SOC at a constant current of 0.33C; Charge from 98% SOC to 100% SOC at a constant current of 0.1C.

[0403] Perform cyclic charge and discharge on the battery according to the above charging strategies until the battery degrades to 70% SOH; During the cycling process, detect the maximum temperature of the end cap of the outer shell of the battery cell and observe whether the welding joint between the first busbar component and the electrode terminal cracks.

[0404] It should be noted here that Cycle Performance Test 1 and Cycle Performance Test 2 are respectively performed on two batteries prepared by the same preparation method.

[0405] The test results of Examples 1-7 and Comparative Examples 1-4 are shown in Table 1.

[0406]

[0407] Referring to Comparative Example 1 in Table 1, the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing are relatively low. Although the battery cell has a relatively small expansion pressure and the weld mark between the electrode terminal and the first busbar component is not easily cracked during cycling, the volume energy density of the battery cell is relatively low.

[0408] Referring to Examples 1-7 and Comparative Example 1, the embodiments of the present application can increase the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing, so that the volume energy density of the battery cell is greater than or equal to 390 Wh / L. Although the expansion pressure of the battery cell is not less than 0.5 MPa, combined with the first busbar component having a double-layer structure, the risk of weld mark cracking caused by the increase in expansion pressure can be reduced, and the reliability of the battery can be improved. The first busbar component has a double-layer structure with strong current-carrying capacity, thereby reducing the heat generation of the first busbar component during cycling, further reducing the heat conducted to the end cap and the electrode assembly, reducing the temperature rise of the battery cell, and improving the cycle performance of the battery.

[0409] Referring to Examples 1-7 and Comparative Examples 2-3, by adjusting parameters such as the single-sided coating weight of the positive electrode film layer, the compaction density of the positive electrode film layer after cold pressing, the single-sided coating weight of the negative electrode film layer, and the compaction density of the negative electrode film layer after cold pressing, the expansion pressure of the battery cell can be limited to not exceed 2.4 MPa, and the volume energy density of the battery cell can reach 415 Wh / L.

[0410] By adjusting the thickness of the single-layer structure of the first current collecting component, the current-carrying capacity and deformability of the first current collecting component can be balanced. When the expansion pressure of the battery cell is 0.5 MPa - 2.4 MPa, limiting the thickness of the single-layer structure of the first current collecting component to not exceed 2.5 mm can reduce the risk of the welding mark between the electrode terminal and the first current collecting component being torn, and reduce the heat generation of the first current collecting component during cycling, thereby reducing the heat conducted to the end cap and the electrode assembly, reducing the temperature rise of the battery cell, and improving the cycling performance of the battery.

[0411] Referring to Examples 1-7 in Table 1, the embodiments of the present application can reduce the heat generation of the first current collecting component and reduce the expansion of the battery cell during rapid charging of the battery, so as to reduce the risk of battery failure. The battery cell of the present application has the ability of rapid charging, and the charging time for the battery cell to charge from 10% SOC to 80% SOC can be 5 minutes to 10.5 minutes.

[0412] Referring to Examples 1-7 in Table 1, the embodiments of the present application can reduce the heat generation of the first current collecting component and reduce the expansion of the battery cell during rapid charging of the battery, so as to reduce the risk of battery failure. The battery cell of the present application has the ability of rapid charging, and the charging time for the battery cell to charge from 10% SOC to 80% SOC can be 5 minutes to 10.5 minutes.

[0413] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0414] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized in that: include: A plurality of battery cells are arranged along a thickness direction of the battery cells, the battery cells include a housing and an electrode assembly contained in the housing, and an expansion pressure of the battery cells in the thickness direction is 0.5 MPa-2.4 MPa; and, a first busbar component electrically connecting at least two of the battery cells arranged along the thickness direction, wherein the first busbar component is a multi-layer structure, Among them, the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator located between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet includes a positive electrode collector and a positive electrode film layer arranged on at least one side of the positive electrode collector, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate with an olivine structure; the negative electrode sheet includes a negative electrode collector and a negative electrode film layer arranged on at least one side of the negative electrode collector, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon-based material.

2. The battery according to claim 1, characterized in that The first busbar member includes a first busbar layer and a second busbar layer which are stacked and connected, and the first busbar layer connects at least two of the battery cells arranged along the thickness direction.

3. The battery according to claim 2, characterized in that The battery cell includes an electrode terminal disposed on the housing, and the electrode terminal is electrically connected to the electrode assembly; A portion of the first bus layer that does not overlap with the second bus layer is connected to the electrode terminal.

4. The battery according to claim 3, characterized in that The first busbar is welded to the electrode terminal, and the welding area between the first busbar and the electrode terminal is greater than or equal to 60 mm 2 .

5. The battery according to any one of claims 2 to 4, 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.

6. The battery according to claim 5, characterized in that The first busbar layer includes a first busbar portion, a second busbar portion, and a first buffer portion, wherein the first busbar portion and the second busbar portion are arranged along the thickness direction and connected to different battery cells, and the first buffer portion connects the first busbar portion and the second busbar portion; At least one of the first confluence portion and the second confluence portion is connected to the bent portion.

7. The battery according to claim 6, characterized in that The bending portion and the first buffer portion are arranged away from each other.

8. The battery according to claim 6 or 7, characterized in that: The second bus layer includes a first stacking portion, a second stacking portion, and a second buffer portion, wherein the first stacking portion is stacked with the first bus portion and connected through at least one bending portion, and the second stacking portion is stacked with the second bus portion and connected through at least one bending portion. The second buffer portion connects the first stacked portion and the second stacked portion; In a stacking direction of the first bus layer and the second bus layer, the second buffer portion at least partially overlaps with the first buffer portion.

9. The battery according to claim 8, characterized in that The second buffer portion and the first buffer portion are arranged in close contact with each other.

10. The battery according to any one of claims 2 to 4, characterized in that: The battery further includes at least one second busbar component, which is a single-layer structure and electrically connects at least two battery cells, and has a thickness greater than that of the first busbar layer, and a thickness greater than that of the second busbar layer.

11. The battery according to claim 10, characterized in that A sum of a thickness of the first bus layer and a thickness of the second bus layer is equal to a thickness of the second bus member.

12. The battery according to any one of claims 2 to 4, characterized in that: The thickness of the first busbar layer is 1 mm to 2.5 mm; and / or The thickness of the second bus layer is 1 mm-2.5 mm.

13. The battery according to any one of claims 2 to 4, characterized in that: The volume energy density of the battery cell is 390 Wh / L-450 Wh / L, and the thickness of the first busbar layer is less than or equal to 2.5 mm; or, The volume energy density of the battery cell is 450 Wh / L-480 Wh / L, and the thickness of the first busbar layer is less than or equal to 2.2 mm.

14. The battery according to any one of claims 2 to 4, characterized in that: The negative electrode active material also includes a silicon-based material; The mass content of silicon element in the silicon-based material in the negative electrode active material is 1%-6%; the thickness of the first bus layer is 1.2mm-2.2mm, and the thickness of the second bus layer is 1.2mm-2.2mm.

15. The battery according to any one of claims 2 to 4, 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; In a stacking direction of the first bus layer and the second bus layer, the first buffer portion protrudes from the first bus portion and the second bus portion; The first bus layer has a recessed portion at a position corresponding to the first buffer portion.

16. The battery according to claim 15, characterized in that The volume energy density of the battery cell is 390 Wh / L-450 Wh / L, and the depth of the recess is 1.2 mm-2.5 mm; or, The volume energy density of the battery cell is 450 Wh / L-480 Wh / L, and the depth of the recess is 1 mm-2.2 mm.

17. The battery according to any one of claims 1 to 4, characterized in that: Among the plurality of battery cells, the battery cells located outermost in the thickness direction are connected to the first busbar member.

18. The battery according to any one of claims 1 to 4, characterized in that: The electrode assembly comprises two first surfaces and two second surfaces, the two first surfaces are arranged opposite to each other along the thickness direction, the two second surfaces are arranged opposite to each other along a direction perpendicular to the thickness direction, and the second surface connects the two first surfaces; An area of ​​the first surface is greater than an area of ​​the second surface.

19. The battery according to any one of claims 1 to 4, characterized in that: The expansion pressure of the battery cell in the thickness direction is 1.5 MPa-2.0 MPa.

20. The battery according to any one of claims 1 to 4, characterized in that: The single-sided coating weight of the negative electrode film layer is 90 mg / 1540 mm 2 Up to 170mg / 1540mm 2 .

21. The battery according to claim 20, characterized in that The single-sided coating weight of the negative electrode film layer is 110 mg / 1540 mm 2 Up to 150mg / 1540mm 2 .

22. The battery according to any one of claims 1 to 4, characterized in that: The compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.15 g / cm 3 Up to 1.36g / cm 3 .

23. The battery according to claim 22, characterized in that The compaction density of the negative electrode film layer at 100% SOC of the battery cell is 1.25 g / cm 3 Up to 1.36g / cm 3 .

24. The battery according to any one of claims 1 to 4, characterized in that: The porosity of the negative electrode sheet is 27%-40%.

25. The battery according to any one of claims 1 to 4, characterized in that: The carbon-based material includes at least one of artificial graphite and natural graphite.

26. The battery according to any one of claims 1 to 4, characterized in that: The negative electrode active material also includes a silicon-based material, and the mass content of silicon in the silicon-based material is 0.3% to 10%.

27. The battery according to claim 26, characterized in that The mass content of silicon element in the silicon-based material in the negative electrode active material is 1% to 6%.

28. The battery according to claim 26, characterized in that The silicon-based material includes at least one of a silicon-oxygen compound and a silicon-carbon composite.

29. The battery according to any one of claims 1 to 4, characterized in that: The negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer, wherein the second negative electrode film layer is arranged between the first negative electrode film layer and the negative electrode current collector; The negative electrode active material includes a first negative electrode active material arranged in the first negative electrode film layer and a second negative electrode active material arranged in the second negative electrode film layer, the first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite and silicon-based materials.

30. The battery according to claim 29, 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.

31. The battery according to claim 30, 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.

32. The battery according to claim 29, 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.

33. The battery according to claim 29, 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.

34. The battery according to claim 29, characterized in that The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm.

35. The battery according to claim 34, characterized in that The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-11.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm to 14.6 μm.

36. The battery according to any one of claims 1 to 4, characterized in that: The specific surface area of ​​the negative electrode active material is 0.5 m 2 / g-3m 2 / g.

37. The battery according to claim 36, characterized in that The specific surface area of ​​the negative electrode active material is 0.6 m 2 / g-1.2m 2 / g.

38. The battery according to any one of claims 1 to 4, characterized in that: The single-sided coating weight of the positive electrode film layer is 200 mg / 1540 mm 2 -370mg / 1540 / mm 2 .

39. The battery according to claim 38, 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 .

40. The battery according to any one of claims 1 to 4, characterized in that: The compaction density of the positive electrode film layer at 100% SOC of the battery cell is 2.50 g / cm 3 Up to 2.80g / cm 3 .

41. The battery according to claim 40, 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 .

42. The battery according to any one of claims 1 to 4, characterized in that The porosity of the positive electrode sheet is 25%-32%.

43. The battery according to any one of claims 1 to 4, characterized in that The thickness of the positive electrode sheet is 0.13mm-0.2mm.

44. The battery according to any one of claims 1 to 4, 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.

45. The battery according to any one of claims 1 to 4, characterized in that The volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm and 0.4µm≤Dv10≤0.7µm.

46. ​​The battery according to any one of claims 1 to 4, characterized in that The battery cell includes an electrolyte contained in the housing.

47. The battery according to claim 46, characterized in that The conductivity of the electrolyte at room temperature is 15 mS / cm to 20 mS / cm.

48. The battery according to claim 46, 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.

49. The battery according to claim 48, characterized in that The carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

50. The battery according to claim 48 or 49, characterized in that The carboxylic acid ester includes R1-COO-R2, and R1 and R2 each independently include an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms.

51. The battery according to claim 46, 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.

52. The battery according to claim 46, characterized in that The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL≤ρ≤1.35 g / mL.

53. The battery according to any one of claims 1 to 4, characterized in that The dimension of the electrode assembly along the thickness direction is T, the thickness of a single layer of the negative electrode sheet is T1, and the number of layers of the negative electrode sheets stacked in the thickness direction is N; T, T1 and N satisfy: 0.3≤(N×T1) / T≤0.

5.

54. The battery according to any one of claims 1 to 4, characterized in that The battery cell takes 5 minutes to 10.5 minutes to charge from 10% SOC to 80% SOC.

55. An electrical device, characterized in that: Comprising a battery according to any one of claims 1-54, the battery is used to provide electrical energy.

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