Battery and power consuming device

Abstract

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

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery and an electrical device. Background Technology

[0002] Batteries are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] In the development of battery technology, improving battery reliability is one of the research directions. Summary of the Invention

[0004] This application provides a battery and an electrical device that improves reliability.

[0005] In a first aspect, embodiments of this application provide a battery comprising a housing and a battery cell. The housing includes a first housing wall. The battery cell is housed within the housing and located below the first housing wall. The battery cell includes a casing, an electrode assembly, and a pressure relief mechanism. The casing is fixed to the first housing wall, and the electrode assembly is housed within the casing. The casing includes a first end wall located on the side of the electrode assembly away from the first housing wall. The pressure relief mechanism is disposed on the first end wall. Under room temperature conditions, the charging time for the battery cell from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes.

[0006] The battery cells have fast charging capabilities, saving charging time and improving user experience. During fast charging, even if a battery cell experiences thermal runaway due to an accident, the high-temperature material generated by the cell can be ejected downwards through a pressure relief mechanism, thereby reducing the thermal impact on the upper part of the battery, lowering the risk of user injury, and improving the reliability of the battery and the electrical devices using it.

[0007] In some embodiments, the pressure relief mechanism and the first end wall are integrally formed. Integrating the pressure relief mechanism with the first end wall saves the space required for connecting the pressure relief mechanism and the first end wall, provides more space for the pressure relief mechanism, improves pressure relief efficiency, and enhances battery reliability.

[0008] In some embodiments, the battery further includes a heat exchanger for exchanging heat with the casing. During battery charging, the heat exchanger can exchange heat with the casing of the battery cell, thereby controlling the temperature of the battery cell within a suitable range, improving the cycle performance of the battery cell, reducing the risk of thermal runaway, and improving reliability.

[0009] In some embodiments, the housing further includes a second end wall and a side wall, the first end wall and the second end wall being disposed opposite each other, the side wall connecting the first end wall and the second end wall and surrounding the electrode assembly, and the second end wall being fixed to the first housing wall. A heat exchanger is disposed on the side wall. A pressure relief mechanism is disposed on the first end wall, and the second end wall is fixed to the first housing wall. Disposing of the heat exchanger on the side wall reduces the risk of interference between the heat exchanger and the pressure relief mechanism and saves space in the vertical direction.

[0010] In some embodiments, the sidewall includes two first sidewalls and two second sidewalls. The two first sidewalls are disposed opposite each other along the thickness direction of the battery cell, and the two second sidewalls are disposed opposite each other along a first direction perpendicular to the thickness direction. Each second sidewall connects to the two first sidewalls. At least one first sidewall of the battery cell is connected to a heat exchanger. The first sidewall is the largest shell wall. Connecting the first sidewall to the heat exchanger can increase the heat exchange area and improve the heat exchange efficiency, thereby reducing the temperature rise of the battery cell during fast charging, reducing the risk of thermal runaway, and improving reliability.

[0011] In some embodiments, the electrode assembly includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes a lithium phosphate with an olivine structure. A first sidewall of the battery cell is connected to a heat exchanger.

[0012] Lithium phosphates with an olivine structure exhibit superior cycle stability. Using olivine-structured lithium phosphates can reduce heat generation in individual battery cells during fast charging, thus lowering the risk of thermal runaway. Furthermore, using olivine-structured lithium phosphates reduces heat exchange requirements. In this embodiment, only one sidewall of the battery cell is connected to the heat exchanger, reducing the number of heat exchangers, saving space, and increasing the battery's energy density.

[0013] In some embodiments, the battery includes multiple battery cell groups and multiple heat exchangers. The multiple battery cell groups are arranged along the thickness direction, and each battery cell group includes at least two battery cells arranged along a first direction. A heat exchanger is provided between every two battery cell groups. One heat exchanger can exchange heat with the battery cells of two battery cell groups simultaneously, which can reduce the number of heat exchangers and improve the space utilization and energy density of the battery.

[0014] In some embodiments, the heat exchanger is bonded to the first sidewall by a first adhesive layer. The first adhesive layer can stably connect the heat exchanger to the first sidewall, thereby improving the stability of heat exchange between the heat exchanger and the battery cell.

[0015] In some embodiments, the heat exchanger includes a heat-conducting plate with flow channels inside for the flow of the heat exchange medium. The heat exchange medium exchanges heat with the battery cells as it flows through the heat-conducting plate.

[0016] In some embodiments, the heat exchanger further includes an insulating layer disposed on the outer surface of the heat-conducting plate and used to separate the heat-conducting plate from the first sidewall. The insulating layer can insulate the heat-conducting plate from the first sidewall, increase the creepage distance between the heat-conducting plate and the first sidewall, and reduce the risk of short circuit.

[0017] In some embodiments, the thermal conductivity of the insulating layer is greater than or equal to 0.1 W / (m•K). The insulating layer has good thermal conductivity, thereby improving heat exchange efficiency.

[0018] In some embodiments, the outer casing is bonded to the first casing wall by a second adhesive layer. The second adhesive layer can fix the battery cells to the first casing wall, thereby improving the stability of the battery cells. The second adhesive layer is easy to mold and helps to simplify the assembly process.

[0019] In some embodiments, the battery cell further includes a first electrode terminal disposed on the first end wall, and the electrode assembly includes an electrode body and a first tab extending from the electrode body, with the first electrode terminal electrically connected to the first tab. Disposing the first electrode terminal on the first end wall can fully utilize the space on the lower side of the battery cell, reduce the risk of the first electrode terminal interfering with the connection between the housing and the first casing wall, and improve space utilization.

[0020] In some embodiments, the area of ​​the portion of the first electrode terminal located outside the first end wall projected onto the first end wall is 200 mm². 2 -600mm 2 The portion of the first electrode terminal located on the outer side of the first end wall has a larger area, which increases the current-carrying area, reduces heat generation, lowers the temperature rise of the first electrode terminal during battery cycling, and improves reliability. The larger exposed area of ​​the first electrode terminal also increases its heat dissipation efficiency.

[0021] In some embodiments, the first end wall has an inner surface facing the electrode assembly, and the first electrode terminal does not extend beyond the inner surface in the direction proximal to the electrode assembly. The first electrode terminal may not occupy the internal space of the housing, thereby improving the space utilization of the battery cell and increasing the energy density of the battery cell.

[0022] In some embodiments, the first electrode terminal includes a connecting portion with a through hole. A first electrode tab passes through the through hole, and a portion of the first electrode tab is located on the side of the connecting portion away from the electrode body and connected to the connecting portion. By providing the through hole, the first electrode tab can be led out to the outside of the connecting portion, thereby reducing the distance between the connecting portion and the electrode body, improving the internal space utilization of the battery cell, and increasing the energy density of the battery cell.

[0023] In some embodiments, the first electrode terminal includes a terminal body and a cover plate. The terminal body is fixed to a first end wall, and a recess is provided on the side of the terminal body away from the electrode body. The bottom wall of the recess serves as a connecting portion. The cover plate is disposed on the side of the connecting portion away from the electrode body and is used to cover the recess. The recess can accommodate a portion of the first tab, thereby improving space utilization. The cover plate isolates the external space of the housing from the through-hole, achieving a seal and reducing the risk of electrolyte leakage.

[0024] In some embodiments, at least a portion of the cover plate is received in a recess. Using a recess to receive the cover plate improves space utilization.

[0025] In some embodiments, the dimension of the first end wall is W1 mm ​​in the width direction of the first end wall, and the dimension of the portion of the first electrode terminal located outside the first end wall is W2 mm. W2 and W1 satisfy: 0.4 ≤ W2 / W1 ≤ 1.

[0026] Setting W2 / W1 to greater than or equal to 0.4 allows for a larger exposed area of ​​the first electrode terminal, increasing the connection area between the first electrode terminal and the busbar, improving current carrying capacity, reducing temperature rise, improving battery cycle performance, and enhancing battery reliability. Limiting W2 / W1 to less than or equal to 1 reduces the additional space occupied by the first electrode terminal in the width direction, improving space utilization.

[0027] In some embodiments, the housing further includes a second housing wall disposed below the battery cell and opposite to the first housing wall. The second housing wall can protect the battery cell from below, reducing the risk of the battery cell being impacted by external impurities and improving battery reliability.

[0028] In some embodiments, the second enclosure wall is spaced apart from the individual battery cells. In the event of thermal runaway of a battery cell, the space between the second enclosure wall and the battery cell can serve as a discharge channel, thereby promptly releasing substances released from the battery cell outside the enclosure and reducing the risk of battery explosion. When the second enclosure wall is subjected to external impact, the space between the second enclosure wall and the battery cell can act as a barrier, reducing the impact force transmitted to the battery cell, lowering the risk of battery cell failure, and improving battery reliability.

[0029] In some embodiments, the battery further includes a support member disposed on the underside of the first end wall and used to support the first end wall. The support member can support the battery cell, thereby improving the stability of the battery cell and enhancing the overall structural strength of the battery.

[0030] In some embodiments, the housing further includes a second housing wall disposed on the lower side of the battery cell, the second housing wall being disposed opposite to the first housing wall. A support member is bonded to the first end wall and the second housing wall. The support member connects the battery cell to the second housing wall, thereby improving the overall structural strength of the battery.

[0031] In some embodiments, the elastic modulus of the support member is less than that of the second housing wall. Because the support member has a lower elastic modulus, it can deform when the second housing wall is subjected to external impact, thereby reducing the force transmitted to the battery cells and lowering the risk of battery cell failure.

[0032] In some embodiments, the housing further includes a plurality of limiting beams connected to the first housing wall. The plurality of limiting beams are spaced apart along the thickness direction of the battery cells, and a plurality of battery cells are disposed between adjacent limiting beams. A support member connects adjacent limiting beams.

[0033] The limiting beam has high resistance to deformation and can effectively constrain the battery cells in the thickness direction; the support can provide constraint force on the limiting beam, thereby reducing the deformation of the limiting beam, limiting the expansion of the battery cells, improving the cycle performance of the battery cells, and reducing the risk of the casing cracking.

[0034] In some embodiments, the support includes a metal strip and an insulating film covering the metal strip, the insulating film separating the metal strip from the first end wall. The metal strip has high strength, enabling it to both support the battery cells and effectively restrain the limiting beam. The insulating film insulates the metal strip from the battery cells, reducing the risk of short circuits.

[0035] In some embodiments, the support member has an internal cavity. By providing the cavity, the weight of the support member can be reduced.

[0036] In some embodiments, the first box wall is used as at least a portion of the vehicle floor. Using the first box wall as the floor can save vehicle parts, improve vehicle integration, and simplify the vehicle assembly process.

[0037] In some embodiments, the battery further includes a mounting beam disposed on the side of the first casing wall opposite to the battery cell. The mounting beam, connected to the first casing wall, can improve the overall strength of the battery. The mounting beam can also provide mounting positions for some components of the electrical device, thereby reducing the number of parts, increasing integration, and simplifying the assembly process.

[0038] In some embodiments, the mounting beam is used to mount the vehicle's seat. Integrating the mounting beam for mounting the seat with the first box wall can improve the overall vehicle utilization rate.

[0039] In some embodiments, the battery cell further includes a sampling element disposed on the casing, which is used to collect the temperature of the casing. The sampling element can collect the temperature of the casing in real time to facilitate monitoring and regulating the temperature of the battery cell, reducing the risk of abnormal temperature rise in the battery cell during fast charging and improving battery reliability.

[0040] In some embodiments, the expansion pressure of a single battery cell in its thickness direction is 0.5 MPa to 2.4 MPa. Limiting the expansion pressure of the battery cell in the thickness direction to 0.5 MPa to 2.4 MPa reduces the expansion deformation of the battery cell during fast charging, improves the cycle performance of the battery cell, reduces the risk of casing cracking, and enhances battery reliability.

[0041] In some embodiments, the battery includes a plurality of battery cells and a plurality of busbars, the plurality of busbars electrically connecting the plurality of battery cells. The plurality of busbars includes at least one first busbar, the first busbar including a first busbar layer and a second busbar layer stacked and connected, the first busbar layer electrically connecting at least two battery cells arranged along the thickness direction.

[0042] The first busbar component has at least a double-layer structure, and both the first and second busbar layers can transmit current. This allows the first busbar component to have a larger current-carrying area, thereby reducing heat generation, improving the battery's fast-charging capability, and reducing the risk of thermal runaway. Provided the current-carrying area meets the requirements, setting the first busbar component as a double-layer structure reduces the thickness requirement of the first busbar layer. During cycling, battery cells expand, stretching the first busbar layer. A thinner first busbar layer is easily deformable to accommodate the deformation of the battery cells, reducing the risk of tearing at the connection between the battery cells and the first busbar layer, and improving battery reliability.

[0043] In some embodiments, the first bus component includes at least one bend that connects a first bus layer and a second bus layer. The bend can connect the first bus layer and the second bus layer and transmit current between the first bus layer and the second bus layer, thereby improving the current carrying capacity of the first bus component.

[0044] In some embodiments, the first bus layer includes a first bus portion, a second bus portion, and a first buffer portion connecting the first bus portion and the second bus portion. The first bus portion and the second bus portion are disposed along the thickness direction and connected to different battery cells. The second bus layer includes a first stack portion, a second stack portion, and a second buffer portion. The first stack portion is stacked with the first bus portion and connected by at least one bending portion. The second stack portion is stacked with the second bus portion and connected by at least one bending portion. The second buffer portion connects the first stack portion and the second stack portion.

[0045] During battery cycling, a portion of the current can be transmitted between the first busbar and the second busbar through the first stack, the second buffer, and the second stack, forming multiple conductive paths between the first and second busbars, thereby improving overcurrent capacity. During the cycling of a single battery cell, the cell expands and applies tension to the first busbar layer; both the first and second buffers can release stress through deformation, thereby reducing the risk of connection failure between the first busbar layer and the battery cell.

[0046] In some embodiments, the housing further includes a plurality of limiting beams connected to the first housing wall. The plurality of limiting beams are spaced apart along the thickness direction of the battery cells, and a plurality of battery cells are disposed between adjacent limiting beams. The distance between two adjacent limiting beams in the thickness direction is D1. In the thickness direction, the distance between two adjacent limiting beams is D1, and the sum of the dimensions of all electrode assemblies located between two adjacent limiting beams and stacked along the thickness direction is D2. 85%≤D2 / D1≤92%.

[0047] Limiting D2 / D1 to less than or equal to 92% reduces the expansion pressure of individual battery cells, minimizes deformation during fast charging, lowers the risk of casing cracking, and improves battery reliability. Limiting D2 / D1 to greater than or equal to 85% improves space utilization in the thickness direction and increases battery energy density. A D2 / D1 range of 85%-92% can, to some extent, balance the expansion pressure of individual battery cells with the battery's energy density.

[0048] In some embodiments, the electrode assembly includes a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material, which includes a lithium phosphate with an olivine structure. The negative electrode includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative active material, which includes a carbon-based material.

[0049] Carbon-based materials exhibit high cycle stability, which can improve the cycle performance of individual battery cells. Lithium-containing phosphates also demonstrate high cycle stability; using lithium-containing phosphates as positive electrode active materials can mitigate cycle degradation caused by excessive temperature rise during fast charging.

[0050] In some embodiments, the single-sided coating weight of the negative electrode film is 90 mg / 1540 mm. 2 Up to 170mg / 1540mm 2 110mg / 1540mm is available as an option. 2 Up to 150mg / 1540mm 2Limiting the single-sided coating weight of the negative electrode film within the aforementioned range can restrict the heat generation per unit area of ​​the negative electrode sheet, reducing the temperature rise of the battery cell, especially during fast charging.

[0051] In some embodiments, the compaction density of the negative electrode film at 100% SOC of the battery cell is 1.15 g / cm³. 3 Up to 1.36 g / cm 3 The option is 1.25g / cm³. 3 Up to 1.36 g / cm 3 When the compaction density of the negative electrode film is within the above range, it is beneficial to improve the energy density of the battery cell; and because the negative electrode active material in the negative electrode film is packed more tightly, the contact resistance between particles is smaller, which can reduce the resistance of the negative electrode sheet, thereby reducing heat generation and improving the battery's fast charging capability.

[0052] In some embodiments, the porosity of the negative electrode is 27%-40%.

[0053] A negative electrode with a porosity greater than or equal to 27% provides space for impurities generated by side reactions, slows down the expansion of the negative electrode, reduces the expansion pressure of the battery cell, decreases the deformation of the battery cell, improves the cycle performance of the battery cell, and enhances the reliability of the battery cell during fast charging. A negative electrode with a porosity less than or equal to 40% can maintain the energy density of the battery cell.

[0054] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. Artificial and natural graphite have good electrical conductivity, which can reduce heat generation of the negative electrode during charging and improve the fast-charging performance of the battery cell.

[0055] In some embodiments, the negative electrode active material further includes a silicon-based material, wherein the mass content of silicon element in the negative electrode active material is 0.3% to 10%, optionally 1% to 6%.

[0056] Introducing silicon-based materials into the negative electrode can increase capacity but also increase the expansion of the negative electrode. Therefore, limiting the mass content of silicon in the negative electrode active material to 0.3% to 10% can, to some extent, balance the energy density and expansion of the battery cell, reduce the deformation of the battery cell, and improve the cycle performance and fast charging capability of the battery cell.

[0057] In some embodiments, the silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

[0058] In some embodiments, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the second negative electrode film layer is disposed between the first negative electrode film layer and the negative electrode current collector. The negative electrode active material includes a first negative electrode active material disposed 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.

[0059] The first and second negative electrode film layers can be configured differently to balance the expansion and capacity of the negative electrode film layer to a certain extent; the double coating can create porosity differences in the negative electrode film layer, reduce ion transport tortuosity, reduce side reactions, and improve the fast charging performance of the battery cell.

[0060] In some embodiments, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer is 3:7 to 7:3, and optionally 4:6 to 6:4. By adjusting the thickness ratio of the first negative electrode film layer to the second negative electrode film layer, the gradient porosity difference between the upper and lower layers can be further increased, the lithium-ion transport tortuosity can be reduced, and the fast charging capability of the battery cell can be improved.

[0061] In some embodiments, the thickness of the first negative electrode film is less than or equal to the thickness of the second negative electrode film, which can further improve the fast charging capability of the battery cell.

[0062] 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.

[0063] The difference in particle size between the first and second negative electrode active materials can improve the fast-charging performance of the battery cell. During fast charging, the overpotential of the first negative electrode film is usually high, and the bottleneck of fast charging mainly lies in the first negative electrode film. However, in the embodiments of this 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 fast-charging performance, and alleviate the problem of ion deposition on the surface of the negative electrode sheet. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film. During charging, the pores can absorb expansion, reduce the expansion of the negative electrode film, and improve the reliability of the battery cell during fast charging. In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and optionally 7.8 μm-11.3 μm.

[0064] Setting the volume average particle size Dv50 of the first negative electrode active material within the aforementioned range can, on the one hand, shorten the solid-phase transport path of lithium ions and improve fast charging performance; on the other hand, the material is less prone to agglomeration during preparation, which can improve the stability of the material; furthermore, the first negative electrode active material within the aforementioned volume average particle size range can cooperate with the second negative electrode active material, which is beneficial for constructing a gradient porosity difference between the first and second negative electrode films, reducing the tortuosity of lithium ion transport, and improving the fast charging performance of the battery cell.

[0065] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm, and optionally 9.5 μm-14.6 μm.

[0066] Setting the volume average particle size Dv50 of the second negative electrode active material within the above range can make the pores of the second negative electrode film layer more abundant, which is beneficial to improving the fast charging capability of the battery cell and reducing the expansion of the negative electrode film layer during charging.

[0067] In some embodiments, the specific surface area of ​​the negative electrode active material is 0.5 m². 2 / g-3m 2 / g, optional 0.6m 2 / g-1.2m 2 / g. The specific surface area of ​​the negative electrode active material is limited to greater than or equal to 0.5m². 2 / g can improve the fast charging capability of individual battery cells; the specific surface area of ​​the negative electrode active material is limited to less than or equal to 3m². 2 / g can reduce side reactions of individual battery cells during storage and reduce expansion pressure.

[0068] In some embodiments, the olivine-structured lithium phosphate has the chemical formula LiFe. 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

[0069] In some embodiments, the single-sided coating weight of the positive electrode film is 200 mg / 1540 mm. 2 -370mg / 1540mm 2 ; 240mg / 1540mg is optional 2 Up to 330mg / 1540mm 2 Setting the single-sided coating weight of the positive electrode film within the above range can limit the heat generation per unit area of ​​the positive electrode sheet, while also improving the energy density and charging rate performance of the battery cell.

[0070] In some embodiments, the compaction density of the positive electrode film at 100% SOC of the battery cell is 2.50 g / cm³. 3 Up to 2.80 g / cm 3 ; 2.55g / cm³ is optional 3 -2.70g / cm 3 When the compaction density of the positive electrode film is within the above range, it is beneficial to improve the energy density of the battery cell; and because the positive electrode active material in the positive electrode film is packed more tightly, the contact resistance between particles is smaller, which can further reduce the resistance of the positive electrode sheet, thereby reducing heat generation under fast charging.

[0071] In some embodiments, the porosity of the positive electrode is 25%-32%. A porosity greater than or equal to 25% provides space for impurities generated by side reactions, reducing the expansion pressure of the battery cell, decreasing cell deformation, and improving cycle performance. A porosity less than or equal to 32% can, to some extent, maintain the energy density of the battery cell.

[0072] In some embodiments, the thickness of the positive electrode sheet is 0.13 mm to 0.2 mm. Using a positive electrode sheet with a smaller thickness can shorten the ion migration path, increase the ion migration rate, reduce the heat generation of the battery cell, and improve the fast charging performance of the battery cell.

[0073] In some embodiments, the ratio of the thickness of the positive current collector to the thickness of the positive electrode film is 0.05-0.3. Limiting the ratio of the positive current collector thickness to the positive electrode film thickness to 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 positive current collector thickness to the positive electrode film thickness to less than or equal to 0.3 can reduce the capacity loss of the positive electrode sheet. The embodiments of this application limit the ratio of the positive current collector thickness to the positive electrode film thickness to 0.05 to 0.3, which can, to a certain extent, balance the fast-charging capability and energy density of the battery cell.

[0074] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm and 0.4µm≤Dv10≤0.7µm. The relatively small particle size of the positive electrode active material results in a shorter lithium-ion insertion / extraction path and less heat generation. Furthermore, the particle size of the positive electrode active material is not too small, which reduces agglomeration during processing and preparation, thus ensuring stable performance of the positive electrode active material.

[0075] In some embodiments, the battery cell includes an electrolyte contained within a casing. During the charging and discharging process of the battery cell, active ions move back and forth between the positive and negative electrode plates, inserting and extracting, while the electrolyte acts as a conductor for the active ions between the positive and negative electrode plates.

[0076] In some embodiments, the electrolyte has a conductivity of 15 mS / cm to 20 mS / cm at room temperature. When the conductivity of the electrolyte is within this range, the ion migration rate in the electrolyte is high, thereby further reducing the internal resistance of the battery cell, reducing heat generation, and improving the fast charging performance of the battery cell.

[0077] In some embodiments, the electrolyte includes an organic solvent, which may include one or more of carbonate solvents and carboxylic acid ester solvents. The use of organic solvents can improve the electrolyte conductivity and reduce viscosity, thereby improving the battery's fast-charging performance.

[0078] In some embodiments, carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0079] In some embodiments, the carboxylic acid ester comprises R1-COO-R2, where R1 and R2 are each independently selected from alkyl groups having 1-5 carbon atoms or haloalkyl groups having 1-5 carbon atoms. The aforementioned chain-like carboxylic acid ester solvents have high conductivity, which is beneficial for improving the fast-charging capability of battery cells.

[0080] In some embodiments, the electrolyte comprises a lithium salt, including lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), wherein the molar concentration of LiFSI is from 0.2 mol / L to 0.5 mol / L, and the molar concentration of LiPF6 is from 0.5 mol / L to 1.0 mol / L. The aforementioned lithium salts are readily dissociated, facilitating rapid lithium-ion migration; furthermore, the electrolyte system is relatively stable and not easily decomposed, thus improving the cycle performance of the battery cells.

[0081] In some embodiments, the electrolyte density ρ at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL. When the electrolyte density ρ is within the above range, the migration rate of lithium ions in the electrolyte is higher, 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.

[0082] Secondly, embodiments of this application provide an electrical device, including a battery provided in any of the embodiments of the first aspect, wherein the battery is used to provide electrical energy. Attached Figure Description

[0083] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0084] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments; Figure 2 A schematic diagram of a battery provided for some embodiments of this application; Figure 3 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application; Figure 4 for Figure 2 Enlarged view of the area within the circle; Figure 5 A partial cross-sectional schematic diagram of a battery provided for some embodiments of this application; Figure 6 Partial cross-sectional schematic diagram of a battery cell provided for other embodiments of this application; Figure 7 A partial cross-sectional schematic diagram of a battery cell provided for some embodiments of this application; Figure 8 A cross-sectional schematic diagram of a battery provided in some embodiments of this application; Figure 9 for Figure 8 Enlarged view of the area within the circle; Figure 10 A cross-sectional schematic diagram of a battery provided for other embodiments of this application; Figure 11 for Figure 10 Enlarged illustration within the box; Figure 12 A cross-sectional schematic diagram of a battery support provided in some embodiments of this application; Figure 13 A schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application; Figure 14 A schematic diagram of a battery cell and a first busbar component provided in some embodiments of this application; Figure 15 for Figure 14 A schematic diagram of the first busbar component; Figure 16 Explosion diagrams of batteries provided for other embodiments of this application; Figure 17 This is a cross-sectional schematic diagram of the negative electrode sheet of a battery cell provided in some embodiments of this application; Figure 18 A cross-sectional schematic diagram of the negative electrode sheet of a battery cell provided in other embodiments of this application; Figure 19 This is a cross-sectional schematic diagram of the positive electrode sheet of a battery cell provided in some other embodiments of this application.

[0085] The annotations in the attached figures are explained as follows: 1. Vehicle; 2. Battery; 3. Controller; 4. Motor; 10. Battery cell; 100. Battery cell pack; 11. Electrode assembly; 111. Positive electrode sheet; 1111. Positive current collector; 1112. Positive electrode film; 112. Negative electrode sheet; 1121. Negative current collector; 1122. Negative electrode film; 11221. First negative electrode film; 11222. Second negative electrode film; 113. Separator; 11a. Electrode body; 11b. First tab; 11c. Second tab; 12. Outer shell; 121. Housing; 122. End cap; 1221. Outer surface; 1222. Inner surface; 1223. Electrode lead-out hole; 12a. First end wall; 12b. Second end wall; 12c. Side wall; 12d. First side wall; 12e. Second side wall; 13. First electrode terminal; 131. Connecting part; 1311. Through hole; 132. Terminal body; 133. Cover plate; 134. Recess; 14. Second electrode terminal; 15. Pressure relief mechanism; 151. Weak part; 152. Pressure relief part; 153. Fixing part; 16. Sampling component; 17. First fixing component; 18. Second fixing component; 20. Box body; 21. First box wall; 22. Second box wall; 23. Frame; 24. Limiting beam; 30. Heat exchanger; 31. Heat conduction plate; 311. Flow channel; 32. Insulation layer; 40. First adhesive layer; 41. Second adhesive layer; 42. Third adhesive layer; 43. Insulating pad; 50. Connecting pipe assembly; 60. Support component; 61. Metal strip; 62. Insulating film; 63. Cavity; 70. First busbar component; 71. First busbar layer; 711. First busbar section; 712. Second busbar section; 713. First buffer section; 72. Second busbar layer; 721. First stacked section; 722. Second stacked section; 723. Second buffer section; 73. Bending section; 80. Install the beam; X, thickness direction; Y, primary direction; Z, vertical direction. Detailed Implementation

[0086] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0087] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0088] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0089] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0090] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0091] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0092] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; 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, it is also expected that ranges of 60 to 110 and 80 to 120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" have been listed in this article; "0 to 5" is just a shortened representation of these numerical combinations. In addition, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0093] In this application, "multiple" means two or more (including two).

[0094] Currently, judging from market trends, battery applications are becoming increasingly widespread. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in aerospace and other fields. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0095] A battery typically refers to a single physical module comprising multiple individual cells to provide higher voltage and capacity. A single cell can be the smallest unit that makes up a battery.

[0096] With the development of batteries, especially their widespread use in daily life, users expect batteries to charge faster to meet the demands of fast-paced modern lifestyles. However, during fast charging, the heat generated by individual battery cells increases, causing them to remain in a high-temperature range throughout the charging process. This exacerbates the risk of thermal runaway and affects user safety.

[0097] In view of this, this application provides a battery in which the pressure relief mechanism of the battery cell is arranged downwards so that when the battery experiences thermal runaway due to fast charging, the generated high-temperature material is sprayed downwards, reducing the risk of injury to the user and improving the reliability of the battery.

[0098] The batteries described in this application are applicable to electrical devices that use batteries. Electrical devices can be equipment that uses batteries as a power source or various energy storage systems that use batteries as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0099] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0100] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0101] like Figure 1 As shown, a battery 2 is installed inside the vehicle 1. The battery 2 can be located at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to power the vehicle 1; for example, the battery 2 can serve as the operating power source for the vehicle 1.

[0102] Vehicle 1 may also include controller 3 and motor 4. Controller 3 is used to control battery 2 to supply power to motor 4, for example, for the power needs of vehicle 1 during start-up, navigation and driving.

[0103] In some embodiments of this application, the battery 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0104] Figure 2 A schematic diagram of a battery provided for some embodiments of this application.

[0105] Reference Figure 2 In some embodiments, the battery 2 includes a housing 20 and a plurality of battery cells 10 housed within the housing 20.

[0106] The battery cell 10 can be a secondary battery. A secondary battery is a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0107] For example, the battery cell 10 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0108] 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. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0109] Multiple battery cells 10 can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 10 are connected in both series and parallel. Multiple battery cells 10 can be directly connected in series, parallel, or in a mixed manner, and then the whole assembly of multiple battery cells 10 is housed in the housing 20. Alternatively, multiple battery cells 10 can first be connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed manner to form a whole assembly, which is then housed in the housing 20.

[0110] In some embodiments, the housing 20 may be part of the vehicle's chassis structure. For example, a portion of the housing 20 may be at least a portion of the vehicle's floor, or a portion of the housing 20 may be at least a portion of the vehicle's crossbeams and longitudinal beams.

[0111] Figure 3 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application.

[0112] Reference Figure 3 In some embodiments, the battery cell 10 includes a housing 12 and an electrode assembly 11 housed within the housing 12.

[0113] The outer shell 12 is a hollow structure, forming an internal space for accommodating the electrode assembly 11 and the electrolyte. The shape of the outer shell 12 can be determined according to the specific shape of the electrode assembly 11. For example, if the electrode assembly 11 has a cuboid structure, a cuboid outer shell can be used.

[0114] As an example, the housing 12 includes a housing 121 and an end cap 122, the housing 121 having an opening and the end cap 122 for closing the opening.

[0115] The housing 121 is a component used to fit the end cap 122 to form an internal cavity of the battery cell 10. The formed internal cavity can be used to accommodate the electrode assembly 11, electrolyte, and other components.

[0116] The housing 121 and the end cap 122 can be separate components. For example, an opening can be provided on the housing 121, and the end cap 122 can be used to close the opening to form an internal cavity for the battery cell 10.

[0117] The housing 121 can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 121 can be determined according to the specific shape and size of the electrode assembly 11. The material of the housing 121 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this application embodiment does not impose any special limitations on this.

[0118] The shape of the end cap 122 can be adapted to the shape of the housing 121 to fit the housing 121. The material of the end cap 122 can be the same as or different from the material of the housing 121. Optionally, the end cap 122 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 122 is not easily deformed when subjected to compression and impact, so that the battery cell 10 can have higher structural strength and improve reliability.

[0119] The end cap 122 is connected to the housing 121 by welding, bonding, snap-fitting or other means.

[0120] The housing 121 may be open at one end or open at both ends. In some examples, the housing 121 may be a structure with an opening on one side, and an end cap 122 is provided and covers the housing 121. In other examples, the housing 121 may also be a structure with openings on both sides, and two end caps 122 are provided, with the two end caps 122 respectively covering the two openings of the housing 121.

[0121] Electrode assembly 11 is a component in the battery cell 10 where electrochemical reactions occur. The housing 121 may contain one or more electrode assemblies 11.

[0122] In some embodiments, the electrode assembly 11 includes a positive electrode and a negative electrode. During the charging and discharging process of the battery cell 10, active ions (e.g., lithium ions) are inserted and extracted back and forth between the positive and negative electrode.

[0123] In some embodiments, the electrode assembly 11 further includes a separator membrane disposed between the positive electrode and the negative electrode, which can prevent short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0124] In some embodiments, the electrode assembly 11 includes an electrode body 11a, a first tab 11b, and a second tab 11c, which extend from the electrode body 11a. The first tab 11b and the second tab 11c have opposite polarities; in other words, one of the first tab 11b and the second tab 11c is a positive tab, and the other is a negative tab.

[0125] As an example, the portion of the positive electrode with active material, the portion of the negative electrode with active material, and the separator constitute the electrode assembly 11. The portion of the positive electrode without active material constitutes the positive tab, and the portion of the negative electrode without active material constitutes the negative tab. The positive tab and the negative tab may be located together at one end of the electrode body 11a or at both ends of the electrode body 11a respectively.

[0126] In some embodiments, the electrode assembly 11 is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0127] In some embodiments, the electrode assembly 11 has a stacked structure.

[0128] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0129] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0130] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0131] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0132] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0133] In some embodiments, the battery cell 10 includes a first electrode terminal 13 and a second electrode terminal 14 that are insulated from each other. The first electrode terminal 13 is electrically connected to a first tab 11b, and the second electrode terminal 14 is electrically connected to a second tab 11c.

[0134] The first electrode terminal 13 and the second electrode terminal 14 are used for electrical connection with an external circuit to realize the charging or discharging of the battery cell 10.

[0135] As an example, the first electrode terminal 13 may be a separately formed component that is mounted on the housing 12. Alternatively, the first electrode terminal 13 may also be part of the housing 12.

[0136] As an example, the second electrode terminal 14 may be a separately formed component that is mounted on the housing 12. Alternatively, the second electrode terminal 14 may also be part of the housing 12.

[0137] In some embodiments, the first electrode terminal 13 and the second electrode terminal 14 are both disposed on the end cap 122.

[0138] In some embodiments, the battery cell 10 further includes a pressure relief mechanism 15. The pressure relief mechanism 15 has a significant impact on the reliability of the battery cell 10. For example, when a short circuit or overcharging occurs, thermal runaway may occur inside the battery cell 10, causing a sudden increase in pressure. In this case, the pressure relief mechanism 15 can be activated to release the internal pressure to the outside, thereby reducing the risk of the battery cell 10 exploding or catching fire.

[0139] For example, the pressure relief mechanism 15 refers to a component or part that is actuated to release internal gas when the internal pressure or temperature of the battery cell 10 reaches a predetermined threshold. This threshold design varies depending on design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell 10.

[0140] The pressure relief mechanism 15 can take the form of an explosion-proof valve, a gas valve, a pressure relief valve, or a safety valve, and can specifically employ a pressure-sensitive element or structure. That is, when the internal pressure of the battery cell 10 reaches a predetermined threshold, the pressure relief mechanism 15 actuates or a weak area provided in the pressure relief mechanism 15 ruptures, thereby forming an opening or channel for internal pressure release. Alternatively, the pressure relief mechanism 15 can also employ a temperature-sensitive element or structure, that is, when the internal temperature of the battery cell 10 reaches a predetermined threshold, the pressure relief mechanism 15 actuates, thereby forming an opening or channel for internal pressure release.

[0141] When the battery cell 10 experiences thermal runaway, the emissions from the battery cell 10 include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of the separator, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0142] In some embodiments, the pressure relief mechanism 15 is disposed on the housing 12. Exemplarily, the pressure relief mechanism 15 may be disposed on the housing 121 or on the end cap 122.

[0143] Figure 4 for Figure 2 Enlarged view of the area within the circle; Figure 5 This is a partial cross-sectional schematic diagram of a battery provided in some embodiments of this application.

[0144] Reference Figures 2 to 5This application provides a battery 2, which includes a housing 20 and a battery cell 10. The housing 20 includes a first housing wall 21. The battery cell 10 is housed within the housing 20 and located below the first housing wall 21. The battery cell 10 includes a casing 12, an electrode assembly 11, and a pressure relief mechanism 15. The casing 12 is fixed to the first housing wall 21, and the electrode assembly 11 is housed within the casing 12. The casing 12 includes a first end wall 12a located on the side of the electrode assembly 11 away from the first housing wall 21. The pressure relief mechanism 15 is disposed on the first end wall 12a. Under room temperature conditions, the charging time for the battery cell 10 from 10% SOC to 80% SOC is less than or equal to 10.5 minutes.

[0145] As an example, room temperature can be an ambient temperature of 30°C.

[0146] The battery cell 10 may include one or more electrode assemblies 11.

[0147] The electrode assembly 11 can be entirely housed within the housing 12, or it can be partially housed within the housing 12.

[0148] As an example, when the battery 2 is installed in an electrical device, the first casing wall 21 may be located on the upper side of the battery cell 10 in the vertical direction Z. During the production and transportation of the battery 2, the first casing wall 21 is not required to be located on the upper side of the battery cell 10.

[0149] The first box wall 21 can be a single-layer structure or a multi-layer structure. The first box wall 21 can be a one-piece molded component or it can be composed of multiple independently molded components connected together.

[0150] The first end wall 12a can be an end cap 122 or a wall of the housing 121.

[0151] The pressure relief mechanism 15 and the first end wall 12a can be integrally formed. In some examples, the pressure relief mechanism 15 and the first end wall 12a can be independently formed components, which can be connected by welding, bonding or other means. For example, the first end wall 12a has a pressure relief hole that extends through the first end wall 12a, and the pressure relief mechanism 15 is mounted on the first end wall 12a and covers the pressure relief hole to separate the spaces on the inner and outer sides of the first end wall 12a. In alternative embodiments, the pressure relief mechanism 15 and the first end wall 12a can also be an integrally formed structure.

[0152] SOC refers to the state of charge of a single battery cell 10.

[0153] For example, 100% SOC and 0% SOC are defined as follows: charging battery cell 10 at a constant current charging rate of 0.33C to the upper limit voltage of battery charging, and then charging at a constant voltage to 0.05C, corresponds to the state of 100% SOC of battery cell 10; discharging battery cell 10 at a constant current discharging rate of 0.33C to the cutoff voltage corresponds to the state of 0% SOC of battery cell 10. For example, the upper limit voltage of battery charging can be 3.8V; the cutoff voltage of battery discharging can be 2.0V.

[0154] For example, the charging time of the battery cell 10 from 10% SOC to 80% SOC is 10.5 min, 10 min, 9.5 min, 9 min, 8.5 min, 8 min, 7.5 min, 7 min, 6.5 min, 6 min, 5.5 min, 5 min, or any combination of two of the above values.

[0155] In this embodiment, the battery cell 10 has fast charging capability, which can save charging time and improve user experience. During the fast charging process of the battery 2, even if the battery cell 10 experiences thermal runaway due to an accident, the high-temperature material generated by the battery cell 10 can be ejected downwards through the pressure relief mechanism 15, thereby reducing the thermal impact on the upper side of the battery 2, reducing the risk of injury to the user, and improving the reliability of the battery 2 and the electrical device using the battery 2.

[0156] In some embodiments, the charging step from 10% SOC to 80% SOC of battery 2 or any of the battery cells 10 comprising battery 2 can be performed as follows: 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.

[0157] As an example, the above charging strategy is carried out in an environment of 30°C.

[0158] In some embodiments, the charging step of the battery cell 10 from 0% SOC to 10% SOC can be performed as follows: charging from 0% SOC to 10% SOC at a constant current of 5.0C.

[0159] In some embodiments, the charging step of the battery cell 10 from 80% SOC to 98% SOC can be performed as follows: Charge from 80% SOC to 85% SOC at a constant current of 1.8C; Charge from 85% SOC to 90% SOC at a constant current of 1.3C; Charge from 90% SOC to 95% SOC at a constant current of 0.7C; Charge from 95% SOC to 98% SOC at a constant current of 0.33C.

[0160] In some embodiments, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be performed as follows: charging from 98% SOC to 100% SOC at a constant current of 0.01C, 0.05C, 0.1C, or 0.3C. Optionally, the charging step of the battery cell 10 from 98% SOC to 100% SOC can be performed as follows: charging from 98% SOC to 100% SOC at a constant current of 0.01C, 0.05C, or 0.1C.

[0161] In some embodiments, during the charging process of battery cell 10 from 10% SOC to 80% SOC at room temperature, the charging current can be 2C-6C, optionally 2.7C-5C. The charging current of battery cell 10 can vary according to the SOC of battery cell 10 during charging.

[0162] 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 and discharging strategies, the negative electrode plate at the battery cell 10 is disassembled, and the lithium deposition area of ​​the negative electrode plate is observed and measured. The ratio of the area of ​​the lithium deposition region to the total area of ​​the negative electrode plate is less than 2%.

[0163] As an example, the discharge strategy employs a constant current discharge of 0.33C to 2.0V.

[0164] As an example, a charging strategy could be: Charge from 0% SOC to 5% SOC at a constant current of 5.0C; Charge from 5% SOC to 10% SOC at a constant current of 5.0C; Charge from 10% SOC to 15% SOC at a constant current of 5.0C; Charge from 15% SOC to 20% SOC at a constant current of 5.0C; Charge from 20% SOC to 25% SOC at a constant current of 5.0C; Charge from 25% SOC to 30% SOC at a constant current of 5.0C; Charge from 30% SOC to 35% SOC at a constant current of 5.0C; Charge from 35% SOC to 40% SOC at a constant current of 5.0C; Charge from 40% SOC to 45% SOC at a constant current of 4.6C; Charge from 45% SOC to 50% SOC at a constant current of 4.3C; Charge from 50% SOC to 55% SOC at a constant current of 4.0C; Charge from 55% SOC to 60% SOC at a constant current of 3.7C; Charge from 60% SOC to 65% SOC at a constant current of 3.4C; Charge from 65% SOC to 70% SOC at a constant current of 3.1C; Charge from 70% SOC to 75% SOC at a constant current of 2.9C; Charge from 75% SOC to 80% SOC at a constant current of 2.7C; Charge from 80% SOC to 85% SOC at a constant current of 1.8C; Charge from 85% SOC to 90% SOC at a constant current of 1.3C; Charge from 90% SOC to 95% SOC at a constant current of 0.7C; Charge from 95% SOC to 98% SOC at a constant current of 0.33C; Charge from 98% SOC to 100% SOC at a constant current of 0.1C.

[0165] The battery cell 10 of this embodiment can be charged from 10% SOC to 80% SOC in 10.5 minutes without lithium plating or with only slight lithium plating, demonstrating good fast charging capability. For example, a ratio of the area of ​​the lithium plating region to the total area of ​​the negative electrode sheet of less than 0.05% can be considered as no lithium plating, and a ratio of the area of ​​the lithium plating region to the total area of ​​the negative electrode sheet of less than 2% and greater than or equal to 0.05% can be considered as slight lithium plating.

[0166] In some embodiments, the pressure relief mechanism 15 includes a weak portion 151. The weak portion 151 is a relatively weak part of the pressure relief mechanism 15, which is a part of the pressure relief mechanism 15 that is prone to breakage, fracture, tearing, or opening.

[0167] In some examples, this application may create grooves, notches, or other structures in a predetermined area of ​​the pressure relief mechanism 15 to reduce the local strength of the pressure relief mechanism 15, thereby forming a weak portion 151 on the pressure relief mechanism 15. For example, a thinning process may be performed on a predetermined area of ​​the pressure relief mechanism 15, and the thinned portion of the pressure relief mechanism 15 forms the weak portion 151. In other examples, the predetermined area of ​​the pressure relief mechanism 15 may be material-treated so that the strength of this area is weaker than the strength of other areas; in other words, this area is the weak portion 151.

[0168] In some embodiments, the pressure relief mechanism 15 and the first end wall 12a are formed independently, and the pressure relief mechanism 15 is fixed to the first end wall 12a.

[0169] For example, the pressure relief mechanism 15 includes a pressure relief part 152, a weak part 151 and a fixing part 153. The weak part 151 is disposed along the outer periphery of the pressure relief part 152 and connects the pressure relief part 152 and the fixing part 153. The fixing part 153 can be used to fix it to the first end wall 12a.

[0170] Optionally, the weak section 151 surrounds the pressure relief section 152.

[0171] Optionally, the fixing part 153 is welded to the first end wall 12a.

[0172] In other embodiments, the pressure relief mechanism 15 and the first end wall 12a are integrally formed. Integrating the pressure relief mechanism 15 and the first end wall 12a into one piece can save the space required for connecting the pressure relief mechanism 15 and the first end wall 12a, provide more space for the pressure relief mechanism 15, improve pressure relief efficiency, and enhance the reliability of the battery 2.

[0173] By molding the pressure relief mechanism 15 and the first end wall 12a as a single unit, the conventional welding process can be eliminated, the thermal impact on the weak part 151 of the pressure relief mechanism 15 can be reduced, and the stability of the pressure relief mechanism 15 can be improved.

[0174] As an example, a groove, notch, or other structure can be formed on the first end wall 12a to create an annular weak portion 151. The weak portion 151 and the area surrounded by the weak portion 151 constitute the pressure relief mechanism 15.

[0175] As an example, the first end wall 12a may be the bottom wall of the housing 121.

[0176] In some embodiments, the battery 2 further includes a heat exchanger 30 for exchanging heat with the housing 12.

[0177] There may be one or more heat exchangers 30. As an example, a battery cell 10 may exchange heat with only one heat exchanger 30 or with multiple heat exchangers 30 simultaneously.

[0178] The heat exchanger 30 can directly contact the outer casing 12 for heat exchange, or it can indirectly exchange heat with the outer casing 12 through other heat-conducting structures.

[0179] The heat exchanger 30 can exchange heat with one or more shell walls of the outer shell 12.

[0180] As an example, the heat exchanger 30 can be a separately molded component disposed within the housing 20, or it can be integrated with the housing 20.

[0181] The heat exchanger 30 can be a single-piece component or it can be assembled from multiple independently formed sub-components.

[0182] During the charging process of battery 2, heat exchanger 30 can exchange heat with the outer casing 12 of battery cell 10, thereby controlling the temperature of battery cell 10 within a suitable range, improving the cycle performance of battery cell 10, reducing the risk of thermal runaway, and improving reliability.

[0183] In some embodiments, the housing 12 further includes a second end wall 12b and a side wall 12c, the first end wall 12a and the second end wall 12b are disposed opposite to each other, the side wall 12c connects the first end wall 12a and the second end wall 12b and surrounds the electrode assembly 11, and the second end wall 12b is fixed to the first housing wall 21.

[0184] As an example, the sidewall 12c can be a cylindrical structure. For example, if the battery cell 10 is a square-shell battery cell, then the sidewall 12c can be a square cylindrical structure; for example, if the battery cell 10 is a cylindrical battery cell, then the sidewall 12c can be a cylindrical structure.

[0185] The heat exchanger 30 can exchange heat with at least one of the first end wall 12a, the second end wall 12b, and the side wall 12c.

[0186] In some examples, the heat exchanger 30 is integrated with the first housing wall 21. For example, the first housing wall 21 has internal channels for the flow of the heat exchange medium. The first housing wall 21 can exchange heat with the second end wall 12b.

[0187] In other examples, the heat exchanger 30 is located below the battery cell 10 and exchanges heat with the first end wall 12a. Optionally, the heat exchanger 30 is disposed away from the pressure relief mechanism 15 to reduce interference of the heat exchanger 30 with the actuation of the pressure relief mechanism 15.

[0188] In some embodiments, the heat exchanger 30 is disposed on the sidewall 12c. The heat exchanger 30 is used for heat exchange with the sidewall 12c.

[0189] The pressure relief mechanism 15 is disposed on the first end wall 12a, the second end wall 12b is fixed to the first box wall 21, and the heat exchanger 30 is disposed on the side wall 12c, which can reduce the risk of interference between the heat exchanger 30 and the pressure relief mechanism 15 and save space in the vertical direction Z.

[0190] In some embodiments, the sidewall 12c includes two first sidewalls 12d and two second sidewalls 12e. The two first sidewalls 12d are disposed opposite each other along the thickness direction X of the battery cell 10, and the two second sidewalls 12e are disposed opposite each other along a first direction Y perpendicular to the thickness direction X. Each second sidewall 12e connects to the two first sidewalls 12d. At least one first sidewall 12d of the battery cell 10 is connected to the heat exchanger 30.

[0191] In some examples, one first sidewall 12d of the battery cell 10 exchanges heat with the heat exchanger 30. Alternatively, both first sidewalls 12d of the battery cell 10 exchange heat with the two heat exchangers 30 respectively.

[0192] The first sidewall 12d is the largest shell wall of the outer shell 12. Connecting the first sidewall 12d to the heat exchanger 30 can increase the heat exchange area and improve the heat exchange efficiency. In turn, during fast charging, it can reduce the temperature rise of the battery cell 10, reduce the risk of thermal runaway, and improve reliability.

[0193] In some embodiments, the thickness direction X, the first direction Y, and the vertical direction Z are perpendicular to each other.

[0194] In some embodiments, the electrode assembly 11 includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes a lithium phosphate with an olivine structure. A first sidewall 12d of the battery cell 10 is connected to the heat exchanger 30.

[0195] Lithium phosphates with an olivine structure exhibit superior cycle stability. Using olivine-structured lithium phosphates can reduce heat generation in the battery cell 10 during fast charging, thus lowering the risk of thermal runaway. Furthermore, using olivine-structured lithium phosphates reduces heat exchange requirements. In this embodiment, only one sidewall 12d of the battery cell 10 is connected to the heat exchanger 30, reducing the number of heat exchangers 30, saving space, and increasing the energy density of the battery 2.

[0196] Of course, in alternative embodiments, if the capacity of the battery 2 meets the requirements, the two first sidewalls 12d of the battery cell 10 can be connected to the two heat exchangers 30 respectively to improve the temperature control effect.

[0197] In some embodiments, the battery 2 includes a plurality of battery cell groups 100, each battery cell group 100 including at least two battery cells 10 arranged along a first direction Y.

[0198] For example, multiple battery cells 10 of battery 2 are arranged in an array within housing 20.

[0199] The number of battery cells 10 in adjacent battery cell groups 100 can be the same or different.

[0200] In some embodiments, a heat exchanger 30 is provided between every two battery cell groups 100.

[0201] The number of battery cells in a 100-cell pack can be either even or odd.

[0202] In some examples, the number of battery cell groups 100 is 2n, where n is a positive integer. A heat exchanger 30 is placed between the (2k-1)th battery cell group 100 and the 2kth battery cell group 100 along the thickness direction X, where k is a natural number from 1 to n. The number of heat exchangers 30 can be n.

[0203] In other examples, the number of battery cell groups 100 is 2n+1, where n is a positive integer. Along the thickness direction X, a heat exchanger 30 is placed between the (2k-1)th battery cell group 100 and the 2kth battery cell group 100, where k is a natural number from 1 to n. The number of heat exchangers 30 can be n+1, with one heat exchanger 30 corresponding to the 2n+1th battery cell group 100.

[0204] In this embodiment, one heat exchanger 30 can exchange heat with two battery cells 10 of the battery cell group 100 at the same time, which can reduce the number of heat exchangers 30 and improve the space utilization and energy density of the battery 2.

[0205] In some embodiments, there are multiple heat exchangers 30, which are arranged along the thickness direction X. Two battery cell groups 100 are provided between adjacent heat exchangers 30.

[0206] In some embodiments, the battery cell group 100 includes m battery cells 10, where m is a positive integer greater than 1. The m battery cells 10 of the battery cell group 100 are connected to the same heat exchanger 30.

[0207] In some embodiments, the heat exchanger 30 is bonded to the first sidewall 12d by a first adhesive layer 40. The first adhesive layer 40 can stably connect the heat exchanger 30 to the first sidewall 12d, thereby improving the stability of heat exchange between the heat exchanger 30 and the battery cell 10.

[0208] In some embodiments, the first adhesive layer 40 is a thermally conductive adhesive layer.

[0209] In some embodiments, the heat exchanger 30 includes a heat-conducting plate 31, and the heat-conducting plate 31 has a flow channel 311 for the flow of the heat exchange medium. The heat exchange medium exchanges heat with the battery cell 10 when it flows through the heat-conducting plate 31.

[0210] As an example, the heat exchange medium can be a liquid or a gas, such as water.

[0211] In some embodiments, the heat-conducting plate 31 is a metal plate or a non-metal plate.

[0212] In some embodiments, the heat exchanger 30 further includes an insulating layer 32, which is disposed on the outer surface of the heat-conducting plate 31 and serves to separate the heat-conducting plate 31 from the first sidewall 12d.

[0213] The insulating layer 32 can insulate the heat-conducting plate 31 from the first sidewall 12d, increase the creepage distance between the heat-conducting plate 31 and the first sidewall 12d, and reduce the risk of short circuit.

[0214] In some embodiments, the insulating layer 32 is bonded to the first adhesive layer 40.

[0215] In some embodiments, the heat-conducting plate 31 is made of an insulating non-metallic material, and the corresponding insulating layer can be omitted.

[0216] In some embodiments, the thermal conductivity of the insulating layer 32 is greater than or equal to 0.1 W / (m•K). The insulating layer 32 has good thermal conductivity, thereby improving heat exchange efficiency.

[0217] In some embodiments, at least a portion of the heat exchanger 30 is configured to be deformable in the thickness direction X. As the battery cell 10 expands during cycling, the heat exchanger 30 can be compressed to provide space for the expansion of the battery cell 10, reduce the pressure on the electrode assembly 11, and improve the cycle performance of the battery cell 10.

[0218] In some embodiments, the battery 2 further includes a connecting pipe assembly 50 for connecting a plurality of heat exchange elements 30. The connecting pipe assembly 50 may communicate with the flow channels 311 of the plurality of heat exchange elements 30, thereby enabling the flow of heat exchange medium within the flow channels 311.

[0219] For example, the connecting pipe assembly 50 includes an inlet pipe and an outlet pipe, the inlet pipe being connected to the flow channels 311 of the plurality of heat exchangers 30, and the outlet pipe being connected to the flow channels 311 of the plurality of heat exchangers 30.

[0220] The inlet pipe and outlet pipe can be located on the same side of the multiple battery cells 10, or they can be respectively located on both sides of the multiple battery cells 10. Optionally, the inlet pipe and outlet pipe are respectively located on both sides of the multiple battery cells 10 along the first direction Y.

[0221] In some embodiments, the battery cell 10 further includes a sampling element 16 disposed on the housing 12, the sampling element 16 being used to collect the temperature of the housing 12.

[0222] The sampling component 16 can be disposed inside the housing 12 or outside the housing 12.

[0223] The sampling device 16 can collect the temperature of the casing 12 in real time, so as to monitor and adjust the temperature of the battery cell 10, reduce the risk of abnormal temperature rise of the battery cell 10 during fast charging, and improve the reliability of the battery 2.

[0224] In some embodiments, the sampling element 16 is disposed on the end cap 122.

[0225] In some embodiments, there are multiple sampling elements 16, and the multiple sampling elements 16 can be disposed at the location where the battery cell 10 has a high temperature during the cycle.

[0226] In some embodiments, the sampling element 16 includes a negative temperature coefficient thermistor.

[0227] In some embodiments, the outer casing 12 is bonded to the first housing wall 21 by a second adhesive layer 41. The second adhesive layer 41 can fix the battery cell 10 to the first housing wall 21, thereby improving the stability of the battery cell 10. The second adhesive layer 41 is easy to mold and helps to simplify the assembly process.

[0228] In some embodiments, the battery cell 10 further includes a first electrode terminal 13 disposed on the first end wall 12a, and the electrode assembly 11 includes an electrode body 11a and a first tab 11b extending from the electrode body 11a, with the first electrode terminal 13 electrically connected to the first tab 11b.

[0229] By placing the first electrode terminal 13 on the first end wall 12a, the space under the battery cell 10 can be fully utilized, reducing the risk of the first electrode terminal 13 interfering with the connection between the outer casing 12 and the first casing wall 21, and improving space utilization.

[0230] In some embodiments, the second electrode terminal 14 is also disposed on the first end wall 12a.

[0231] In some embodiments, at least a portion of the first electrode terminal 13 is located outside the first end wall 12a.

[0232] The first end wall 12a has an outer surface 1221 on the side away from the electrode assembly 11. Exemplarily, at least a portion of the first electrode terminal 13 is located below the plane of the outer surface 1221 of the first end wall 12a.

[0233] In some examples, the first electrode terminal 13 may be entirely located outside the first end wall 12a; alternatively, in other examples, a portion of the first electrode terminal 13 is located outside the first end wall 12a, and another portion passes through the first end wall 12a and extends into the housing 12.

[0234] The portion of the first electrode terminal 13 located outside the first end wall 12a can be used to connect to the busbar component of the battery 2.

[0235] In some embodiments, the area of ​​the portion of the first electrode terminal 13 located outside the first end wall 12a projected onto the first end wall 12a is 200 mm². 2 -600mm 2 200mm is optional 2 250mm 2 300mm 2 350mm 2 400mm 2 450mm 2 500mm 2 550mm 2 Or 600mm 2 .

[0236] For example, the projection of the portion of the first electrode terminal 13 located outside the first end wall 12a onto the first end wall 12a is the projection of the portion of the first electrode terminal 13 located outside the first end wall 12a onto the vertical direction Z. The vertical direction Z is parallel to the thickness direction of the first end wall 12a.

[0237] The portion of the first electrode terminal 13 located outside the first end wall 12a has a large area, which increases the current flow area, reduces heat generation, lowers the temperature rise of the first electrode terminal 13 during battery cycling, and improves reliability. The large exposed area of ​​the first electrode terminal 13 also increases its heat dissipation efficiency.

[0238] In some embodiments, in the width direction of the first end wall 12a, the dimension of the first end wall 12a is W1 mm, and the dimension of the portion of the first electrode terminal 13 located outside the first end wall 12a is W2 mm. W2 and W1 satisfy: 0.4≤W2 / W1≤1.

[0239] Optionally, the width direction of the first end wall 12a is parallel to the thickness direction X of the battery cell 10.

[0240] As an example, W2 / W1 can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0241] Setting W2 / W1 to be greater than or equal to 0.4 allows the first electrode terminal 13 to have a larger exposed area, increasing the connection area between the first electrode terminal 13 and the busbar component, improving current carrying capacity, reducing temperature rise, improving the cycle performance of battery 2, and enhancing the reliability of battery 2. Limiting W2 / W1 to less than or equal to 1 reduces the extra space occupied by the first electrode terminal 13 in the width direction, improving space utilization.

[0242] In some embodiments, W2 / W1 is 0.6-0.9.

[0243] In some embodiments, the first electrode terminal 13 and the second electrode terminal 14 are spaced apart along the length direction of the first end wall 12a. Optionally, the length direction of the first end wall 12a is parallel to the first direction Y.

[0244] In some embodiments, in the length direction of the first end wall 12a, the pressure relief mechanism 15 is located between the first electrode terminal 13 and the second electrode terminal 14.

[0245] Figure 6 This is a partial cross-sectional schematic diagram of a battery cell provided for other embodiments of this application.

[0246] In some embodiments, refer to Figure 6 The first end wall 12a has an inner surface 1222 facing the electrode assembly 11, and the first electrode terminal 13 does not extend beyond the inner surface 1222 in the direction close to the electrode assembly 11.

[0247] In this embodiment, the first electrode terminal 13 may not occupy the internal space of the outer casing 12, thereby improving the space utilization of the battery cell 10 and increasing the energy density of the battery cell 10.

[0248] In some embodiments, the first end wall 12a includes an electrode lead-out hole 1223, and the first electrode terminal 13 is located outside the electrode lead-out hole 1223. In the axial direction of the electrode lead-out hole 1223, the first electrode terminal 13 covers the electrode lead-out hole 1223.

[0249] In some embodiments, the battery cell 10 further includes a first fixing member 17 and a second fixing member 18. The first fixing member 17 at least partially surrounds and is fixed to the first electrode terminal 13, and the second fixing member 18 is connected to the first fixing member 17 and fixedly connected to the first end wall 12a.

[0250] In some embodiments, a portion of the second fastener 18 is embedded within the first fastener 17.

[0251] In some embodiments, the second fastener 18 is welded to the first end wall 12a.

[0252] In some embodiments, the first fastener 17 is an insulating component. The first fastener 17 is formed by injection molding.

[0253] Figure 7 This is a partial cross-sectional schematic diagram of a battery cell provided for some embodiments of this application.

[0254] Reference Figure 7 In some embodiments, the first electrode terminal 13 includes a connecting portion 131, the connecting portion 131 is provided with a through hole 1311, the first electrode tab 11b passes through the through hole 1311, and a portion of the first electrode tab 11b is located on the side of the connecting portion 131 away from the electrode body 11a and is connected to the connecting portion 131.

[0255] By providing a through hole 1311, the first tab 11b can be led out to the outside of the connecting part 131, thereby reducing the distance between the connecting part 131 and the electrode body 11a, improving the internal space utilization of the battery cell 10, and increasing the energy density of the battery cell 10.

[0256] In some embodiments, the first tab 11b is welded to the connection portion 131. The first tab 11b can be directly connected to the first electrode terminal 13, thereby eliminating the need for a conventional adapter and improving energy density.

[0257] In some embodiments, the first electrode terminal 13 includes a terminal body 132 and a cover plate 133. The terminal body 132 is fixed to the first end wall 12a and includes a connecting portion 131. The cover plate 133 is disposed on the side of the connecting portion 131 away from the electrode body 11a and connected to the terminal body 132. The cover plate 133 separates the through hole 1311 from the external space of the battery cell 10.

[0258] In some embodiments, a recess 134 is provided on the side of the terminal body 132 away from the electrode body 11a, and the bottom wall of the recess 134 is a connecting portion 131. A cover plate 133 is provided on the side of the connecting portion 131 away from the electrode body 11a and is used to cover the recess 134.

[0259] The recess 134 can accommodate a portion of the first tab 11b, thereby improving space utilization. The cover 133 separates the external space of the housing 12 from the through hole 1311, achieving a seal and reducing the risk of electrolyte leakage.

[0260] In some embodiments, at least a portion of the cover plate 133 is received in the recess 134. Utilizing the recess 134 to receive the cover plate 133 improves space utilization.

[0261] In some embodiments, the cover plate 133 is welded to the terminal body 132.

[0262] In some embodiments, the cover plate 133 and the first electrode tab 11b are spaced apart to reduce the risk of the cover plate 133 and the first electrode tab 11b pressing against each other.

[0263] In some embodiments, the through hole 1311 is a strip hole that extends along the length direction of the first end wall 12a.

[0264] Figure 8 A cross-sectional schematic diagram of a battery provided in some embodiments of this application; Figure 9 for Figure 8 Enlarged view of the area within the circle.

[0265] Reference Figure 8 and Figure 9 In some embodiments, the housing 20 further includes a second housing wall 22, which is disposed on the lower side of the battery cell 10 and is disposed opposite to the first housing wall 21.

[0266] The second box wall 22 can be a single-layer structure or a multi-layer structure.

[0267] The second enclosure wall 22 can protect the battery cell 10 from the bottom, thereby reducing the risk of the battery cell 10 being impacted by external impurities and improving the reliability of the battery 2.

[0268] The battery cell 10 is fixed to the first box wall 21. The weight of the battery cell 10 is mainly borne by the first box wall 21. Therefore, the second box wall 22 can have a smaller thickness and weight.

[0269] In some embodiments, the housing 20 further includes a frame 23, with a first housing wall 21 and a second housing wall 22 located above and below the frame 23, respectively. The first housing wall 21, the second housing wall 22, and the frame 23 define an internal space for accommodating the battery cell 10 and the heat exchanger 30.

[0270] In some embodiments, the second housing wall 22 is spaced apart from the battery cell 10.

[0271] In the event of thermal runaway of battery cell 10, the space between the second enclosure wall 22 and battery cell 10 can serve as a discharge channel, thereby promptly discharging the substances released by battery cell 10 outside the enclosure 20 and reducing the risk of battery 2 explosion. When the second enclosure wall 22 is subjected to external impact, the space between the second enclosure wall 22 and battery cell 10 can act as a barrier, reducing the impact force transmitted to battery cell 10, lowering the risk of battery cell 10 failure, and improving the reliability of battery 2.

[0272] In some embodiments, the pressure relief mechanism 15, the first electrode terminal 13, and the second electrode terminal 14 are all arranged downwards, which can make full use of the bottom space of the housing 20 and improve the space utilization rate in the vertical direction Z.

[0273] In some embodiments, the battery 2 further includes a support member 60, which is disposed on the lower side of the first end wall 12a and is used to support the first end wall 12a.

[0274] There can be one or more support members 60.

[0275] As an example, the support member 60 can be in contact with the second box wall 22 or spaced apart from the second box wall 22.

[0276] The support member 60 can support the battery cell 10, thereby improving the stability of the battery cell 10 and enhancing the overall structural strength of the battery 2.

[0277] In some embodiments, the housing 20 further includes a second housing wall 22 disposed on the lower side of the battery cell 10, the second housing wall 22 being disposed opposite to the first housing wall 21. The support member 60 is bonded to the first end wall 12a and the second housing wall 22.

[0278] The support member 60 connects the battery cell 10 to the second box wall 22, thereby improving the overall structural strength of the battery 2.

[0279] In some embodiments, the support member 60 is provided with a third adhesive layer 42 on both sides, and the support member 60 is bonded to the second box wall 22 and the first end wall 12a respectively through the two third adhesive layers 42.

[0280] In some embodiments, the elastic modulus of the support 60 is less than the elastic modulus of the second box wall 22.

[0281] The support member 60 has a low elastic modulus. When the second box wall 22 is subjected to external impact, the support member 60 can deform to reduce the force transmitted to the battery cell 10 and reduce the risk of battery cell 10 failure.

[0282] In some embodiments, the support member 60 has a cavity inside. By providing the cavity, the weight of the support member 60 can be reduced, and the support member 60 can be provided with compressibility.

[0283] In some embodiments, there are multiple support members 60. The support members 60 extend along the thickness direction X of the battery cell 10, and the multiple support members 60 are spaced apart along a first direction Y.

[0284] In some embodiments, the first end wall 12a is supported by two support members 60 at both ends along the first direction Y. Exemplarily, in the first direction Y, the first electrode terminal 13, the pressure relief mechanism 15, and the second electrode terminal 14 are disposed between the two support members 60.

[0285] In some embodiments, a support member 60 can simultaneously support two adjacent battery cells 10 along the first direction Y.

[0286] In some embodiments, a gap is provided between the support member 60 and the heat exchange member 30 in the vertical direction Z.

[0287] Figure 10 A cross-sectional schematic diagram of a battery provided for other embodiments of this application; Figure 11 for Figure 10 Enlarged illustration within the box; Figure 12 A cross-sectional schematic diagram of a battery support provided in some embodiments of this application; Figure 13 This is a schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application.

[0288] Reference Figures 10 to 13 In some embodiments, the housing 20 further includes a plurality of limiting beams 24 connected to the first housing wall 21. The plurality of limiting beams 24 are spaced apart along the thickness direction X of the battery cell 10, and a plurality of battery cells 10 are provided between adjacent limiting beams 24.

[0289] There may be two or more limiting beams 24. As an example, a battery cell 10 is provided between any two adjacent limiting beams 24.

[0290] The limiting beam 24 can be used to limit the expansion deformation of the battery cell 10 in the thickness direction X. The limiting beam 24 can directly abut against the battery cell 10 in the thickness direction X; alternatively, other components can be provided between the limiting beam 24 and the battery cell 10, that is, the limiting beam 24 limits the expansion of the battery cell 10 through these components.

[0291] The limiting beam 24 has high resistance to deformation and can effectively constrain the battery cell 10 in the thickness direction X, reduce the maximum expansion of the battery cell 10 in the thickness direction X, and improve the cycle performance of the battery cell 10.

[0292] In some embodiments, an insulating pad 43 is provided between the battery cell 10 and the limiting beam 24.

[0293] In some embodiments, the support member 60 is connected to the adjacent limiting beam 24.

[0294] There can be one or more support members 60.

[0295] The support member 60 can be connected to the limiting beam 24 by welding, snap-fitting, fastener connection or other connection methods.

[0296] The support member 60 can be a strip structure, a linear structure, a beam structure, or other structures. For example, the support member 60 extends along the thickness direction X of the battery cell 10.

[0297] During the cycling process of the battery cell 10, the battery cell 10 expands and exerts a force on the limiting beam 24. The support member 60 can provide a restraining force on the limiting beam 24, thereby reducing the deformation of the limiting beam 24 and limiting the expansion of the battery cell 10, improving the cycling performance of the battery cell 10, and reducing the risk of cracking of the housing 20.

[0298] In some embodiments, the support 60 may apply a preload to the adjacent limiting beam 24.

[0299] In some embodiments, the support member 60 is a strip structure. The strip structure is low in cost and occupies little space; using a strip structure for the support member 60 can improve the space utilization inside the battery 2 and increase the energy density of the battery 2.

[0300] In some embodiments, the support 60 includes a metal strip 61 and an insulating film 62 covering the metal strip 61, the insulating film 62 separating the metal strip 61 from the first end wall 12a.

[0301] For example, metal strip 61 includes steel strip.

[0302] The metal strip 61 has high strength, which can both support the battery cell 10 and effectively restrain the limiting beam 24. The insulating film 62 can insulate and isolate the metal strip 61 from the battery cell 10, reducing the risk of short circuit.

[0303] In some embodiments, the support member 60 has a cavity 63 inside. By providing the cavity 63, the weight of the support member 60 can be reduced.

[0304] In some embodiments, the metal strip 61 has a cavity 63.

[0305] In some embodiments, the support member 60 is bonded to the first end wall 12a. The support member 60 is bonded to the battery cell 10, which can increase the connection strength between the battery cell 10 and the housing 20, reduce the shaking of the battery cell 10 relative to the housing 20 when the battery 2 is subjected to impact, and improve the reliability and stability of the battery 2.

[0306] In some embodiments, the support member 60 and the second box wall 22 are spaced apart in the vertical direction Z. Alternatively, the support member 60 is bonded to the second box wall 22.

[0307] In some embodiments, the support 60 is detachably connected to the limiting beam 24.

[0308] In some embodiments, the support member 60 and the limiting beam 24 may be connected by, but not limited to, bolted connections, snap-fit ​​connections or other detachable connection methods.

[0309] In some embodiments, the expansion pressure of the battery cell 10 in its thickness direction X is 0.5MPa-2.4MPa.

[0310] Optionally, the expansion pressure of the battery cell 10 in the thickness direction X is 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa, 1.6MPa, 1.7MPa, 1.8MPa, 1.9MPa, 2.0MPa, 2.1MPa, 2.2MPa, 2.3MPa, or 2.4MPa.

[0311] As an example, the expansion pressure of the battery cell 10 can be measured in the following manner: At an ambient temperature of 45℃, the battery cells were discharged to 2.0V at a constant current discharge rate of 1C. The battery cell is clamped between two clamping plates, which are located on both sides of the battery cell along the thickness direction X and cover the large surface (the large surface is the outer surface of the first sidewall 12d). At an ambient temperature of 45°C, the battery cells were charged to 3.8V at a constant current charging rate of 0.8C, and the pressure exerted by the battery cells on the clamping plate was detected and recorded. The battery cells were cyclically charged and discharged according to the above charging and discharging strategies until the battery cells reached 70% SOH (i.e., the capacity retention rate of the battery cell = the discharge capacity of the battery cell / the nominal capacity of the battery cell = 70%), and the maximum pressure exerted by the battery cells on the clamping plate was recorded. The expansion pressure Q of a single battery cell in the thickness direction is calculated as: maximum pressure / large surface area.

[0312] The expansion pressure of the battery cell 10 is related to the density of the electrode assembly 11. The battery cell 10 has an expansion pressure greater than or equal to 0.5 MPa in the thickness direction X, thereby increasing the density of the electrode assembly 11 and improving the energy density of the battery cell 10. The expansion pressure of the battery cell 10 in the thickness direction X is less than or equal to 2.4 MPa to limit the deformation of the electrode assembly 11 during cycling, reduce the risk of wrinkling and deformation of the separator of the electrode assembly 11 and the risk of increased local spacing between the positive and negative electrode plates, reduce polarization, and improve the cycle performance of the battery cell 10.

[0313] In this embodiment, the expansion pressure of the battery cell 10 in the thickness direction X is limited to 0.5MPa-2.4MPa to reduce the expansion deformation of the battery cell 10 during fast charging, improve the cycle performance of the battery cell 10, reduce the risk of cracking of the casing 20, and improve the reliability of the battery 2.

[0314] Limiting the expansion pressure of the battery cell 10 to 1.5MPa-2.0MPa reduces the strength requirements of the limiting beam 24 and lowers costs.

[0315] In some embodiments, the housing 20 further includes a plurality of limiting beams 24 connected to the first housing wall 21. The plurality of limiting beams 24 are spaced apart along the thickness direction X of the battery cells 10, and a plurality of battery cells 10 are disposed between adjacent limiting beams 24. The distance between two adjacent limiting beams 24 in the thickness direction X is D1. The sum of the dimensions of all electrode assemblies 11 located between two adjacent limiting beams 24 and stacked along the thickness direction X is D2. 85% ≤ D2 / D1 ≤ 92%.

[0316] For example, the number of battery cell groups 100 between adjacent limiting beams 24 is M1. The number of battery cells 10 arranged in a row in the thickness direction X between adjacent limiting beams 24 is M1. Each battery cell 10 includes M2 electrode assemblies 11.

[0317] When battery 2 is at 0% SOC, remove battery cell 10 and measure the distance between the two limiting beams 24 in the thickness direction X as D1; ​​disassemble the removed battery cell 10 and take out the electrode assembly 11, measure the thickness of M1×M2 electrode assemblies 11 arranged in the thickness direction X and sum them to obtain D2.

[0318] For example, when the battery cell 10 is at 0% SOC, the dimension of the electrode assembly 11 along the thickness direction X is T; D2 = M1 × M2 × T.

[0319] D2 / D1 is related to the expansion pressure of the battery cell 10. In this embodiment, D2 / D1 is limited to less than or equal to 92% to reduce the expansion pressure of the battery cell 10, reduce the deformation of the battery cell 10 during fast charging, reduce the risk of cracking of the casing 20, and improve the reliability of the battery 2. Limiting D2 / D1 to greater than or equal to 85% can improve the space utilization in the thickness direction X and increase the energy density of the battery 2. Limiting D2 / D1 to 85%-92% can, to a certain extent, balance the expansion pressure of the battery cell 10 and the energy density of the battery 2.

[0320] Figure 14 A schematic diagram of a battery cell and a first busbar component provided in some embodiments of this application; Figure 15 for Figure 14 A schematic diagram of the first busbar component.

[0321] Reference Figure 14 and Figure 15 In some embodiments, the battery 2 includes a plurality of battery cells 10 and a plurality of busbars, the plurality of busbars electrically connecting the plurality of battery cells 10.

[0322] Multiple busbar components can connect multiple battery cells 10 in series, parallel, or mixed.

[0323] Multiple busbar components can use the same structure or different structures.

[0324] In some embodiments, the plurality of busbar components include at least one first busbar component 70, the first busbar component 70 including a first busbar layer 71 and a second busbar layer 72 stacked and connected, the first busbar layer 71 being electrically connected to at least two battery cells 10 arranged along the thickness direction X.

[0325] Multiple bus components can all be the first bus component 70, or some of them can be the first bus component 70.

[0326] The first bus layer 71 and the second bus layer 72 can be integrally formed. Alternatively, the first bus layer 71 and the second bus layer 72 can also be formed independently and connected by welding or other means.

[0327] The first busbar component 70 has at least a double-layer structure, and both the first busbar layer 71 and the second busbar layer 72 of the first busbar component 70 can transmit current. This allows the first busbar component 70 to have a higher current-carrying area, thereby reducing the heat generation of the first busbar component 70, improving the fast charging capability of the battery 2, and reducing the risk of thermal runaway.

[0328] Provided the flow area meets the requirements, setting the first busbar component 70 as a double-layer structure can reduce the thickness requirement of the first busbar layer 71. During cycling, the battery cell 10 expands, stretching the first busbar layer 71. The first busbar layer 71 has a small thickness and is easily deformable to accommodate the deformation of the battery cell 10, reducing the risk of tearing at the connection between the battery cell 10 and the first busbar layer 71, and improving the reliability of the battery 2.

[0329] In some embodiments, the thickness of the first busbar 71 is 1mm-2.5mm. Optionally, the thickness of the first busbar 71 is 1.2mm-1.8mm. As examples, the thickness of the first busbar 71 is 1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, or 2.5mm. The embodiments of this application select the thickness of the first busbar 71 according to the expansion pressure of the battery cell 10, which can, to a certain extent, balance the current-carrying capacity and deformability of the first busbar 71, thereby improving the fast-charging capability and reliability of the battery 2.

[0330] In some embodiments, the thickness of the second bus layer 72 is 1mm-2.5mm. Optionally, the thickness of the second bus layer 72 is 1.2mm-1.8mm. As an example, the thickness of the second bus layer 72 is 1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, or 2.5mm.

[0331] The thickness of the second busbar 72 can be selected based on the thickness of the first busbar 71 and the current carrying capacity of the battery to the first busbar component. For example, when the thickness of the first busbar 71 is small, the second busbar 72 may have a greater thickness than the first busbar 71 to improve the current carrying capacity of the first busbar component.

[0332] In some embodiments, the first bus layer 71 is connected to the first electrode terminal 13 of one battery cell 10 and the second electrode terminal 14 of another battery cell 10 to connect the two battery cells 10 in series. Alternatively, the first bus layer 71 is connected to the first electrode terminals 13 of two battery cells 10 to connect the two battery cells 10 in parallel.

[0333] In some embodiments, the first bus layer 71 is soldered to the first electrode terminal 13 and / or the second electrode terminal 14.

[0334] In some embodiments, the first busbar component 70 includes at least one bend 73, which connects the first busbar layer 71 and the second busbar layer 72.

[0335] There can be one or more bends 73.

[0336] The bend 73 can connect the first bus layer 71 and the second bus layer 72 and transmit current between the first bus layer 71 and the second bus layer 72, thereby improving the current carrying capacity of the first bus component 70.

[0337] In some embodiments, the first busbar 71 includes a first busbar 711, a second busbar 712, and a first buffer 713 connecting the first busbar 711 and the second busbar 712. The first busbar 711 and the second busbar 712 are disposed along the thickness direction X and connected to different battery cells 10.

[0338] For example, the first busbar 711 may be connected to the electrode terminals (first electrode terminal 13 or second electrode terminal 14) of one or more battery cells 10. The second busbar 712 may be connected to the electrode terminals (first electrode terminal 13 or second electrode terminal 14) of one or more battery cells 10.

[0339] During the cycling process of the battery cell 10, the battery cell 10 expands and applies tension to the first busbar 71; the first buffer 713 can release stress through deformation, thereby reducing the stress at the connection between the first busbar 711 and the battery cell 10 and the connection between the second busbar 712 and the battery cell 10, and reducing the risk of failure of the connection between the first busbar 71 and the battery cell 10.

[0340] In some embodiments, the bent portion 73 is not directly connected to the first buffer portion 713. This reduces the impact of the bent portion 73 on the deformation of the first buffer portion 713, thus lowering the difficulty of deforming the first buffer portion 713.

[0341] In some embodiments, the first buffer portion 713 includes an arched structure.

[0342] In some embodiments, the first busbar 711 is located below the first electrode terminal 13 of a battery cell 10 and connected to the first electrode terminal 13, and the second busbar 712 is located below the second electrode terminal 14 of another battery cell 10 and connected to the second electrode terminal 14.

[0343] In some embodiments, the second bus layer 72 includes a first stacked portion 721, a second stacked portion 722, and a second buffer portion 723. The first stacked portion 721 is stacked with the first bus layer 711 and connected by at least one bend 73. The second stacked portion 722 is stacked with the second bus layer 712 and connected by at least one bend 73. The second buffer portion 723 connects the first stacked portion 721 and the second stacked portion 722.

[0344] For example, the first stacked portion 721 is attached to the first busbar portion 711, and the second stacked portion 722 is attached to the second busbar portion 712.

[0345] During the cycling process of battery 2, a portion of the current can be transmitted between the first busbar 711 and the second busbar 712 through the first stacked portion 721, the second buffer portion 723, and the second stacked portion 722. Multiple conductive paths are formed between the first busbar 711 and the second busbar 712, thereby improving the overcurrent capacity.

[0346] During the cycling process of the battery cell 10, the battery cell 10 expands and applies tension to the first busbar 71; the first buffer 713 and the second buffer 723 can both release stress through deformation, thereby reducing the risk of failure of the connection between the first busbar 71 and the battery cell 10.

[0347] In some embodiments, the second buffer portion 723 overlaps at least partially with the first buffer portion 713, which brings the deformation areas of the first buffer portion 713 and the second buffer portion 723 closer together, thereby reducing the risk of the first buffer portion 713 and the second buffer portion 723 interfering with other parts during deformation.

[0348] In some embodiments, the second busbar 72 is located on the side of the first busbar 71 away from the battery cell 10.

[0349] In some embodiments, the second bus layer 72 is located below the first bus layer 71.

[0350] In some embodiments, the multiple busbar components further include a second busbar component (not shown) with a single-layer structure. In the battery 2, the expansion amount of battery cells 10 at different locations may vary. For battery cells 10 with smaller expansion amounts, a second busbar component with a single-layer structure can be used; compared to the first busbar component 70, the second busbar component has a simpler structure, is easier to manufacture, and saves costs. The thickness of the second busbar component is greater than the thickness of the first busbar layer 71 and the thickness of the second busbar layer 72, and its current-carrying capacity meets the requirements.

[0351] Figure 16 This is an exploded schematic diagram of a battery provided for other embodiments of this application.

[0352] Reference Figure 16 In some embodiments, the first box wall 21 is used as at least a portion of the vehicle floor. Using the first box wall 21 as the floor can save vehicle parts, improve vehicle integration, and simplify the vehicle assembly process.

[0353] In some embodiments, the battery 2 further includes a mounting beam 80 disposed on the side of the first housing wall 21 opposite to the battery cell 10.

[0354] The mounting beam 80 is connected to the first housing wall 21, which can improve the overall strength of the battery 2. The mounting beam 80 can also provide mounting positions for some components of the electrical device, thereby reducing the number of parts, improving integration, and simplifying the assembly process.

[0355] In some embodiments, the mounting beam 80 is used to mount the vehicle's seat. This embodiment can improve the overall space utilization of the vehicle. The mounting beam 80, combined with the first box wall 21, can save more space in the vertical direction Z, thereby allowing for a further increase in the size of the battery cell 10 in the vertical direction Z, and improving the energy density of the battery 2.

[0356] Figure 17 This is a cross-sectional schematic diagram of the negative electrode sheet of a battery cell provided in some embodiments of this application; Figure 18 A cross-sectional schematic diagram of the negative electrode sheet of a battery cell provided in other embodiments of this application; Figure 19 This is a cross-sectional schematic diagram of the positive electrode sheet of a battery cell provided in some other embodiments of this application.

[0357] Reference Figure 13 as well as Figure 17-19 In some embodiments, the electrode assembly 11 includes a positive electrode 111, a negative electrode 112, and a separator 113 located between the positive electrode 111 and the negative electrode 112. The positive electrode 111 includes a positive current collector 1111 and a positive electrode film layer 1112 disposed on at least one side of the positive current collector 1111. The positive electrode film layer 1112 includes a positive active material, which includes a lithium phosphate with an olivine structure. The negative electrode 112 includes a negative current collector 1121 and a negative electrode film layer 1122 disposed on at least one side of the negative current collector 1121. The negative electrode film layer 1122 includes a negative active material, which includes a carbon-based material.

[0358] In this embodiment, the negative electrode film layer 1122 may be provided only on 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.

[0359] Optionally, a negative electrode film layer 1122 is provided on both opposite surfaces of the negative electrode current collector 1121 along its thickness direction. The negative electrode film layer 1122 on the two surfaces of the negative electrode current collector 1121 can be made of the same negative electrode active material or different negative electrode active materials; the thickness of the negative electrode film layer 1122 on the two surfaces of the negative electrode current collector 1121 can be the same or different.

[0360] Exemplarily, the negative electrode current collector 1121 may be a metal foil or a composite current collector. Examples of metal foils include at least one foil selected from copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material layer may include at least one selected from copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include at least one selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0361] The negative electrode active material includes carbon-based materials. Carbon-based materials have high cycle stability and can improve the cycle performance of the battery cell 10.

[0362] The positive current collector 1111 has two surfaces opposite each other in its thickness direction, and the positive electrode film layer 1112 is disposed on either or both of the two opposite surfaces of the positive current collector 1111.

[0363] Exemplarily, the positive current collector 1111 may be a metal foil or a composite current collector. Examples of metal foils include at least one foil selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material layer may include at least one selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include at least one selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0364] Lithium-containing phosphates have high cycle stability. Using lithium-containing phosphates as positive electrode active materials can improve the cycle degradation caused by excessive temperature rise during fast charging of battery cell 10.

[0365] In some embodiments, a portion of the negative current collector 1121 is not covered by the negative electrode film layer 1122; the portion of the negative current collector 1121 not covered by the negative electrode film layer 1122 can be used to form a negative electrode tab.

[0366] 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 any range of two of the above values.

[0367] In some embodiments, the compaction density of the negative electrode film 1122 at 100% SOC of the battery cell is 1.15 g / cm³. 3 Up to 1.36 g / cm 3 .

[0368] For example, at 100% SOC, the compaction density of the negative electrode film layer 1122 of the battery cell 10 is 1.15 g / cm³. 3 1.18 g / cm 3 1.20g / cm 3 1.22g / cm 3 1.25g / cm 3 1.28g / cm 3 1.3g / cm 3 1.32g / cm 3 1.35g / cm 3 1.36 g / cm 3 Or a range consisting of any two of the above values.

[0369] For example, the compaction density of the negative electrode film layer of the battery cell 10 at 100% SOC has a well-known meaning 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 negative electrode sheet with single-sided coating is taken (if it is a double-sided coated negative electrode sheet, the negative electrode film layer on one side can be wiped off first), and it is cut into a small circular piece with an area of ​​S1, weighed and 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 and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the negative electrode film layer = (weight of negative electrode sheet M1 - weight of negative electrode current collector M0) / S1, the thickness of the negative electrode film layer = thickness of negative electrode sheet H1 - thickness of negative electrode current collector H0, and the compaction density of the negative electrode film layer = single-sided coating weight of the negative electrode film layer / thickness of the negative electrode film layer.

[0370] The compaction density of the negative electrode film 1122 is related to the expansion of the battery cell 10 at 100% charge. The compaction density of the negative electrode film 1122 is limited to 1.15 g / cm³. 3Up to 1.36 g / cm 3 It can balance the energy density and expansion pressure of the battery cell 10 to a certain extent, reduce the deformation of the battery cell 10, and reduce the risk of failure of the connection between the battery cell 10 and the busbar component.

[0371] 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 material in the negative electrode film layer 1122 is densely packed, the contact resistance between particles is small, which can reduce the resistance of the negative electrode sheet 112, thereby reducing heat generation and improving the fast charging capability of the battery 2.

[0372] When the compaction density of the negative electrode film layer 1122 is within the above range, the fast charging capability of the battery cell 10 can be improved. A lower compaction density of the negative electrode film layer 1122 can increase the porosity of the negative electrode sheet 112, slow down the expansion of the negative electrode sheet, and reduce the expansion pressure of the battery cell 10.

[0373] In some embodiments, the compaction density of the negative electrode film 1122 at 100% SOC of the battery cell is 1.25 g / cm³. 3 Up to 1.36 g / cm 3 This can increase the energy density of a single battery cell by 10.

[0374] In some embodiments, the single-sided coating weight of the negative electrode film 1122 is 90 mg / 1540 mm. 2 Up to 170mg / 1540mm 2 For example, the single-sided coating weight of the negative electrode film layer 1122 is 90 mg / 1540.25 mm. 2 92mg / 1540.25mm 2 95mg / 1540.25mm 2 96mg / 1540.25mm 2 100mg / 1540.25mm 2 102mg / 1540.25mm 2 104mg / 1540.25mm 2 105mg / 1540.25mm 2 108mg / 1540.25mm 2 110mg / 1540.25mm 2 112mg / 1540.25mm 2 114mg / 1540.25mm 2 115mg / 1540.25mm 2 116mg / 1540.25mm 2 118mg / 1540.25mm2 120mg / 1540.25mm 2 122mg / 1540.25mm 2 125mg / 1540.25mm 2 128mg / 1540.25mm 2 130mg / 1540.25mm 2 132mg / 1540.25mm 2 135mg / 1540.25mm 2 137mg / 1540.25mm 2 140mg / 1540.25mm 2 142mg / 1540.25mm 2 145mg / 1540.25mm 2 148mg / 1540.25mm 2 150mg / 1540.25mm 2 152mg / 1540.25mm 2 155mg / 1540.25mm 2 160mg / 1540.25mm 2 165mg / 1540.25mm 2 167mg / 1540.25mm 2 170mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0375] The single-sided coating weight of the negative electrode film 1122 is related to the expansion of the negative electrode film. Therefore, the single-sided coating weight of the negative electrode film 1122 is limited to 90 mg / 1540 mm. 2 Up to 170mg / 1540mm 2 It can balance the energy density and expansion pressure of the battery cell 10 to a certain extent, reduce the deformation of the battery cell 10, reduce the risk of failure of the connection between the battery cell 10 and the busbar component, and improve reliability.

[0376] In addition, the single-sided coating weight of the negative electrode film 1122 is limited to 90 mg / 1540 mm. 2 Up to 170mg / 1540mm 2 It can also limit the heat generation per unit area of ​​the negative electrode 112, reduce the temperature rise of the battery cell 10, especially during fast charging.

[0377] In some embodiments, the single-sided coating weight of the negative electrode film 1122 is 110 mg / 1540 mm. 2 Up to 150mg / 1540mm2 This is to further balance the energy density and expansion pressure of the battery cell 10.

[0378] In some embodiments, the porosity of the negative electrode 112 is 27%-40%. As an example, the porosity of the negative electrode 112 may be 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%.

[0379] The porosity of the negative electrode sheet can be defined as the percentage of the pore volume within the negative electrode sheet to its total volume. For example, when the battery cell is at 0% state of charge, a negative electrode sheet with double-sided coating is taken; the porosity of the negative electrode sheet is measured using a true density meter AccuPyc II 1340 according to national standard GB / T 24586-2009.

[0380] In this embodiment, the porosity of the negative electrode 112 is greater than or equal to 27%, which provides space for impurities generated by side reactions in the negative electrode 112, slows down the expansion of the negative electrode 112, reduces the expansion pressure of the battery cell 10, reduces the deformation of the battery cell 10, improves the cycle performance of the battery cell 10, and enhances the reliability of the battery cell 10 during fast charging. The porosity of the negative electrode 112 is less than or equal to 40%, which balances the energy density of the battery cell 10.

[0381] In some embodiments, the carbon-based material includes graphite particles with a graphitization degree of 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 a range consisting of any two of the above values.

[0382] When the degree of graphitization of the graphite particles is within the above range, the graphite particles have excellent electrical conductivity, which can reduce the heat generation of the negative electrode 112 and the heat generation of the battery cell 10; and can improve the fast charging performance of the battery cell 10.

[0383] In some embodiments, the carbon-based material includes at least one of artificial graphite and natural graphite. Artificial and natural graphite have good electrical conductivity, which can reduce heat generation of the negative electrode 112 during charging and improve the fast-charging performance of the battery cell 10.

[0384] In some embodiments, the negative electrode active material further includes a silicon-based material. The introduction of a silicon-based material can improve the capacity of the negative electrode active material and increase the energy density of the battery cell 10.

[0385] In some embodiments, the mass content of silicon in the silicon-based material in the negative electrode active material is 0.3% to 10%, optionally 1% to 6%. Exemplarily, the mass content of silicon in the negative electrode active material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or a range consisting of any two of the above values.

[0386] Introducing silicon-based materials into the negative electrode 112 can both increase capacity and increase the expansion of the negative electrode 112. Therefore, limiting the mass content of silicon in the negative electrode active material to 0.3% to 10% can, to a certain extent, balance the energy density and expansion of the battery cell 10, reduce the deformation of the battery cell 10, and improve the cycle performance and fast charging capability of the battery cell 10.

[0387] The qualitative and quantitative analysis of each substance or element in this application can be performed using suitable equipment and methods known to those skilled in the art. Relevant testing methods can be referenced from domestic and international testing standards and enterprise standards. Furthermore, those skilled in the art can adaptively modify certain testing steps / instrument parameters from the perspective of testing accuracy to obtain more accurate results. One testing method can be used for qualitative or quantitative analysis, or several testing methods can be used in combination for qualitative or quantitative determination.

[0388] For example, silicon-based materials can be subjected to X-ray powder diffraction tests and qualitative analysis on negative electrode sheets or negative electrode active materials in accordance with the general rules of X-ray diffraction analysis in JIS / K0131-1996.

[0389] 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.

[0390] In some embodiments, the silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

[0391] In some embodiments, the negative electrode active material may include, in addition to carbon-based materials and optionally silicon-based materials, at least one of tin-based materials and lithium titanate. Tin-based materials may include at least one of elemental tin, tin oxide, and tin alloy materials.

[0392] In some embodiments, the negative electrode film layer 1122 in this application includes at least one film layer; in other words, the negative electrode film layer 1122 can be a single film layer or at least two film layers. Optionally, the negative electrode film layer 1122 includes at least two film layers.

[0393] When the negative electrode film layer 1122 is a single layer, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. When a single layer is used, the volume average particle size Dv50 of the negative electrode active material is from 8.2 μm to 13.5 μm. Exemplarily, the volume average particle size Dv50 of the negative electrode active material is 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.2 μm, 13.5 μm, or a range consisting of any two of the above values.

[0394] When the negative electrode film layer 1122 employs at least two film layers, the negative electrode active material in the negative electrode film layer 1122 includes a carbon-based material, and optionally also includes a silicon-based material. The silicon-based material may be located in one of the at least two film layers, or in at least two of the at least two film layers. The negative electrode film layer 1122 may include two film layers, three film layers, four film layers, or even more film layers.

[0395] In some embodiments, the negative electrode film layer 1122 includes a first negative electrode film layer 11221 and a second negative electrode film layer 11222, wherein the second negative electrode film layer 11222 is disposed between the first negative electrode film layer 11221 and the negative electrode current collector 1121. The negative electrode active material includes a first negative electrode active material disposed in the first negative electrode film layer 11221 and a second negative electrode active material disposed in the second negative electrode film layer 11222. 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.

[0396] 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 can be irregular.

[0397] The first negative electrode film layer 11221 and the second negative electrode film layer 11222 can be configured differently, thereby taking into account the expansion and capacity of the negative electrode film layer 1122 to a certain extent; the double coating can create the porosity difference of the negative electrode film layer 1122, reduce the tortuosity of ion transport, reduce side reactions, and improve the fast charging performance of the battery cell 10.

[0398] Artificial graphite can have a small volume average particle size Dv50, which can shorten the solid-phase transport path of lithium ions and improve fast charging performance. On the other hand, the material is less prone to agglomeration during the preparation process, which can improve the stability of the material.

[0399] In some embodiments, the thickness ratio of the first negative electrode film layer 11221 to the thickness ratio of the second negative electrode film layer 11222 is 3:7 to 7:3. As an example, the thickness ratio of the first negative electrode film layer 11221 to the thickness ratio of the second negative electrode film layer 11222 is 3:7, 4:6, 5:5, 6:4 or 7:3.

[0400] Optionally, the thickness ratio of the first negative electrode film layer 11221 to the thickness ratio of the second negative electrode film layer 11222 is 4:6 to 6:4.

[0401] By adjusting the thickness ratio of the first negative electrode film layer 11221 and the second negative electrode film layer 11222, the gradient porosity difference between the upper and lower layers can be further increased, the lithium-ion transport tortuosity can be reduced, and the fast charging capability of the battery cell 10 can be improved.

[0402] In some embodiments, the thickness of the first negative electrode film layer 11221 is less than or equal to the thickness of the second negative electrode film layer 11222, which can further improve the fast charging capability of the battery cell 10.

[0403] In some embodiments, the first negative electrode active material is in particulate form, and the second negative electrode active material is in particulate form.

[0404] 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.

[0405] The difference in particle size between the first and second negative electrode active materials improves the fast-charging performance of the battery cell 10. During fast charging, the overpotential of the first negative electrode film 11221 is typically high, and the bottleneck of fast charging mainly lies in the first negative electrode film 11221. However, in this embodiment, the particle size of the first negative electrode active material is relatively small, which can shorten the solid-phase transport path of ions, improve fast-charging performance, and alleviate the problem of ion deposition on the surface of the negative electrode sheet 112. The particle size of the second negative electrode active material is relatively large, which can form larger pores in the second negative electrode film 11222. During charging, the pores can absorb expansion, reducing the expansion of the negative electrode film 1122 and improving the reliability of the battery cell 10 during fast charging.

[0406] In some embodiments, the volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-14.3 μm, and optionally 7.8 μm-11.3 μm. For example, 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 of any two of the above values.

[0407] The volume average particle size Dv50 of the first negative electrode active material is set to 7.8μm-14.3μm. On the one hand, this can shorten the solid-phase transport path of lithium ions and improve fast charging performance. On the other hand, the material is less prone to agglomeration during preparation, which can improve the stability of the material. Furthermore, the first negative electrode active material in the above-mentioned volume average particle size range can cooperate with the second negative electrode active material, which is conducive to constructing the gradient porosity difference between the first negative electrode film layer 11221 and the second negative electrode film layer 11222, reducing the tortuosity of lithium ion transport, and improving the fast charging performance of the battery cell 10.

[0408] The volume average particle size Dv50 of a material refers to the particle size corresponding to 50% of the volume distribution, and the volume average particle size Dv10 of a material refers to the particle size corresponding to 10% of the volume distribution. They can be detected using equipment and methods known in the art. For example, using the negative electrode active material as a sample, the Dv50 and Dv10 of the particles can be tested using a Mastersizer 2000E laser particle size analyzer according to the testing standard GB / T 19077-2016.

[0409] In some embodiments, the volume average particle size Dv50 of the second negative electrode active material is 9.5 μm-18.5 μm, and optionally 9.5 μm-14.6 μm.

[0410] For example, 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 any two of the above values.

[0411] The volume average particle size Dv50 of the second negative electrode active material is between 9.5 μm and 18.5 μm, which can make the pores of the second negative electrode film 11222 more abundant, which is beneficial to improving the fast charging capability of the battery cell 10 and reducing the expansion of the negative electrode film 1122 during the charging process.

[0412] In some embodiments, the first negative electrode active material comprises graphite particles, wherein the volume average particle size Dv50 of the graphite particles in the first negative electrode film layer 11221 is 7.8 μm to 14.3 μm, optionally 7.8 μm to 11.3 μm. Optionally, the first negative electrode active material comprises artificial graphite.

[0413] The second negative electrode active material includes graphite particles with a volume average particle size Dv50 of 9.5 μm to 18.5 μm, optionally from 9.5 μm to 14.6 μm. Optionally, the second negative electrode active material includes natural graphite.

[0414] In some embodiments, the specific surface area of ​​the negative electrode active material is 0.5 m². 2 / g-3m 2 / g, optional 0.6m 2 / g-1.2m 2 / g. For example, the specific surface area of ​​the negative electrode active material is 0.5m². 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1.0m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g, 2.0m 2 / g、2.1m 2 / g, 2.2m 2 / g, 2.3m 2 / g, 2.4m 2 / g, 2.5m 2 / g, 2.6m 2 / g, 2.7m 2 / g, 2.8m 2 / g, 2.9m 2 / g, 3.0m 2 / g or a range consisting of any two of the above values.

[0415] The specific surface area of ​​a material is a well-known concept in the art and can be tested using equipment and methods known in the art. For example, it can be tested according to the testing standard GB / T 19587-2017, using the negative electrode active material as a sample and testing the specific surface area using a Tri-Star 3020 specific surface area and pore size analyzer from Micromeritics, Inc.

[0416] In this application embodiment, the specific surface area of ​​the negative electrode active material is limited to greater than or equal to 0.5 m². 2 / g can improve the fast charging capability of a single battery cell; the specific surface area of ​​the negative electrode active material is limited to less than or equal to 3m². 2 / g can reduce the side reactions of the battery cell 10 during storage, slow down the expansion of the negative electrode, and reduce the expansion pressure.

[0417] In some embodiments, the chemical formula of the lithium phosphate with an olivine structure is LiFe. 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

[0418] In some embodiments, the lithium phosphate with an olivine structure or its modified material can be a lithium phosphate with an olivine structure, or a material obtained by coating and modifying it. For example, the lithium phosphate with an olivine structure includes phosphate particles and an ion-conducting layer, wherein the ion-conducting layer coats the surface of the phosphate particles and contains one or more elements selected from C, Fe, Ti, Zr, Hf, Ge, and Sn.

[0419] In some embodiments, the mass percentage of olivine-structured lithium phosphate or its modified material in the positive electrode active material may be greater than or equal to 80% and less than or equal to 100%, and the positive electrode active material of this application can be considered as an olivine-structured lithium phosphate or its modified material system. When the mass percentage of olivine-structured lithium phosphate or its modified material is less than 100%, the positive electrode active material may also include commonly used positive electrode active materials, such as, but not limited to, at least one of lithium transition metal oxides. Examples of lithium 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.

[0420] Optionally, the mass percentage of the lithium phosphate containing olivine structure or its modified material in the positive electrode active material is 100%.

[0421] In some embodiments, the compaction density of the positive electrode film 1112 at 100% SOC of the battery cell is 2.50 g / cm³. 3 Up to 2.80 g / cm 3 ; 2.55g / cm³ is optional 3 -2.70g / cm 3 For example, when the battery cell 10 is at 100% state of charge (SOC), the compaction density of the positive electrode film layer 1112 is 2.50 g / cm³. 3 2.52g / cm 3 2.55g / cm 3 2.56 g / cm 3 2.57g / cm 3 2.58g / cm 3 2.60g / cm 3 2.62 g / cm 3 2.65g / cm 3 2.68g / cm 3 2.30g / cm 3 2.32 g / cm 3 2.75g / cm 3 2.78g / cm 3 2.80g / cm 3 Or a range consisting of any two of the above values.

[0422] 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 material in the positive electrode film layer 1112 is packed more tightly and the contact resistance between particles is smaller, it can further reduce the resistance of the positive electrode sheet 111, thereby reducing the heat generation under fast charging.

[0423] In this embodiment, the compaction density of the positive electrode film 1112 at 100% SOC of the battery cell is a term known in the art, meaning that the positive electrode sheet 111 is disassembled from the battery cell 10 at 100% SOC, and the compaction density of the positive electrode film 1112 is measured. Exemplarily, the method for testing the compaction density of the positive electrode film 1112 can be the same as the method for testing the compaction density of the negative electrode film 1122.

[0424] In some embodiments, the single-sided coating weight of the positive electrode film 1112 is 200 mg / 1540 mm. 2 -370mg / 1540mm 2 ; 240mg / 1540mg is optional 2Up to 330mg / 1540mm 2 For example, the single-sided coating weight of the positive electrode film layer 1112 is 200 mg / 1540.25 mm. 2 210mg / 1540.25mm 2 220mg / 1540.25mm 2 230mg / 1540.25mm 2 240mg / 1540.25mm 2 250mg / 1540.25mm 2 260mg / 1540.25mm 2 270mg / 1540.25mm 2 280mg / 1540.25mm 2 290mg / 1540.25mm 2 300mg / 1540.25mm 2 310mg / 1540.25mm 2 320mg / 1540.25mm 2 330mg / 1540.25mm 2 340mg / 1540.25mm 2 350mg / 1540.25mm 2 360mg / 1540.25mm 2 370mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0425] In the embodiments of this application, the single-sided coating weight of the positive electrode film layer 1112 has a meaning known in the art and can be detected using equipment and methods known in the art, such as the single-sided coating weight test method of the negative electrode film layer 1122 described above.

[0426] The single-sided coating weight of the positive electrode film 1112 was set at 200 mg / 1540 mm. 2 -370mg / 1540mm 2 This can limit the heat generation per unit area of ​​the positive electrode 111, and can also improve the energy density and charging rate performance of the battery cell 10.

[0427] In some embodiments, the porosity of the positive electrode 111 is 25%-32%. As an example, the porosity of the positive electrode 111 may be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, or any combination of two of the above values.

[0428] In the embodiments of this application, the porosity of the positive electrode 111 has a meaning known in the art and can be detected using equipment and methods known in the art, such as the porosity testing method for the negative electrode 112.

[0429] The porosity of the positive electrode 111 is greater than or equal to 25%, which provides space for impurities generated by side reactions in the positive electrode 111, reduces the expansion pressure of the battery cell, reduces the deformation of the battery cell 10, and improves the cycle performance of the battery cell 10. The porosity of the positive electrode 111 is less than or equal to 32%, which can, to some extent, maintain the energy density of the battery cell 10.

[0430] In some embodiments, the thickness of the positive electrode 111 may be 0.13mm-0.2mm. As an example, the thickness of the positive electrode 111 may be 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm or any range of two of the above values.

[0431] In the embodiments of this application, the thickness of the positive electrode 111 has a meaning known in the art and can be detected using equipment and methods known in the art, such as measuring the thickness of the positive electrode 111 using a micrometer.

[0432] By using a positive electrode 111 with a smaller thickness, the ion migration path can be shortened, the ion migration rate can be increased, the heat generation of the battery cell 10 can be reduced, and the fast charging performance of the battery cell 10 can be improved.

[0433] In some embodiments, the ratio of the thickness of the positive current collector 1111 to the thickness of the positive electrode film 1112 is 0.05 to 0.3. Exemplarily, in an embodiment of this application, the thickness of the positive electrode film 1112 is the thickness of the positive electrode film 1112 located on one side of the positive current collector 1111.

[0434] For example, the ratio of the thickness of the positive 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 any two of the above values.

[0435] Limiting the ratio of the thickness of the positive current collector 1111 to the thickness of the positive electrode film 1112 to greater than or equal to 0.05 can improve the current-carrying capacity of the positive current collector 1111, reduce the temperature rise of the positive electrode sheet 111, and improve the fast-charging performance of the battery cell 10. Limiting the ratio of the thickness of the positive current collector 1111 to the thickness of the positive electrode film 1112 to less than or equal to 0.3 can reduce the capacity loss of the positive electrode sheet 111. In this embodiment, the ratio of the thickness of the positive current collector 1111 to the thickness of the positive electrode film 1112 is limited to 0.05 to 0.3, which can, to a certain extent, balance the fast-charging capability and energy density of the battery cell 10.

[0436] The thickness of the positive electrode film and the thickness of the positive current collector are well-known in the art and can be detected using well-known equipment and methods. For example, the thickness of the positive electrode sheet can be measured with a micrometer, the film layer on the surface of the positive current collector can be removed, and the thickness of the positive current collector can be measured with a micrometer. When the positive electrode film is coated on one side, the thickness of the positive electrode film is the thickness of the positive electrode sheet minus the thickness of the positive current collector; when the positive electrode film is coated on both sides, the thickness of the positive electrode film is: (thickness of the positive electrode sheet minus the thickness of the positive current collector) / 2.

[0437] In some embodiments, the thickness of the positive electrode current collector 1111 is 10 μm to 15 μm, optionally 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 any combination of 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 superior, and the battery cell 10 can have a higher energy density.

[0438] In some embodiments, a portion of the positive current collector 1111 is not covered by the positive electrode film layer 1112; the portion of the positive current collector 1111 not covered by the positive electrode film layer 1112 can be used to form a positive electrode tab.

[0439] In some embodiments, the volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm and 0.4µm≤Dv10≤0.7µm.

[0440] For example, the Dv50 of the positive electrode active material can be 1µm, 1.1µm, 1.15µm, 1.2µm, 1.25µm, 1.3µm, 1.35µm, 1.4µm, 1.45µm, 1.5µm, 1.55µm, 1.6µm, 1.65µm, 1.7µm, 1.75µm, 1.8µm, 1.85µm, 1.9µm, 1.95µm, 2µm, or any range of two of the above values.

[0441] For example, the Dv10 of the positive electrode active material can be 0.4µm, 0.45µm, 0.5µm, 0.55µm, 0.6µm, 0.65µm, 0.7µm, or any range of two of the above values.

[0442] The particle size of the positive electrode active material is relatively small, the lithium ion insertion and extraction path in the positive electrode active material is shorter, and the heat generation is less; moreover, the particle size of the above positive electrode active material is not too small, which can reduce agglomeration during the processing and preparation process, so as to make the performance of the positive electrode active material stable.

[0443] The volume average particle size Dv50 of a material refers to the particle size corresponding to 50% of the volume distribution, and the volume average particle size Dv10 of a material refers to the particle size corresponding to 10% of the volume distribution. They can be detected using equipment and methods known in the art. For example, using positive electrode active material as a sample, the Dv50 and Dv10 of the particles can be tested using a Mastersizer 2000E laser particle size analyzer according to the testing standard GB / T 19077-2016.

[0444] In some embodiments, the battery cell 10 includes an electrolyte contained within the housing 12. During the charging and discharging process of the battery cell 10, active ions are inserted and extracted back and forth between the positive electrode 111 and the negative electrode 112, and the electrolyte plays a role in conducting active ions between the positive electrode 111 and the negative electrode 112.

[0445] In some embodiments, the conductivity of the electrolyte at room temperature (e.g., 25°C) is from 13 mS / cm to 20 mS / cm, optionally from 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 any range of two of the above values.

[0446] 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.

[0447] The conductivity of the electrolyte is ionic conductivity, which can be detected using equipment and methods known in the art, such as by referring to industry standard HG-T 4067-2015.

[0448] In some embodiments, the density ρ of the electrolyte at room temperature (e.g., 25°C) satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

[0449] For example, 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 of any two of the above values.

[0450] When the electrolyte density ρ 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.

[0451] In the embodiments of this application, the density of the electrolyte has a meaning known in the art and can be detected using equipment and methods known in the art, such as referring to GB / T 2013-2010 for testing.

[0452] In some embodiments, the electrolyte comprises an organic solvent, which includes one or more of carbonate solvents and carboxylic acid ester solvents.

[0453] In some embodiments, the carboxylic acid ester solvent includes a chain-like carboxylic acid ester solvent, wherein the chain-like carboxylic acid ester solvent comprises 5% to 75% by mass of the organic solvent. Exemplarily, the mass content of the chain-like carboxylic acid ester solvent is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or any combination of two of the above values. When the mass content of the chain-like carboxylic acid ester solvent is within the above range, the viscosity of the electrolyte system is relatively low, which is beneficial for lithium ion migration.

[0454] In some embodiments, the chain carboxylic acid ester solvent has a mass content of 30% to 70% in the organic solvent.

[0455] In some embodiments, the carboxylic acid ester comprises R1-COO-R2, where R1 and R2 are each independently selected from alkyl groups having 1-5 carbon atoms or haloalkyl groups having 1-5 carbon atoms. The aforementioned chain-like carboxylic acid ester solvents have high conductivity, which is beneficial for improving the fast-charging capability of the battery cell 10.

[0456] In some embodiments, carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0457] Further optionally, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0458] The combined use of the aforementioned carbonate solvents and chain carboxylic acid ester solvents improves the conductivity of the electrolyte, which is beneficial for lithium ion migration.

[0459] Further optionally, the carbonate solvent in the organic solvent has a mass content of 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 any combination of two of the above values. The carbonate solvent at the above mass contents can further improve the conductivity of the electrolyte, which is beneficial for lithium ion migration.

[0460] For example, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the carbonate solvent content is 25% to 60% by mass.

[0461] The use of organic solvents can improve the conductivity of the electrolyte and reduce its viscosity, thereby improving the fast charging performance of the battery.

[0462] In some embodiments, the electrolyte comprises a lithium salt. The lithium salt includes one or more of fluorosulfonyl imide salts and lithium hexafluorophosphate (LiPF6). These lithium salts are readily dissociated, facilitating rapid lithium-ion migration; and the electrolyte system is relatively stable and does not easily decompose, thus improving the cycle performance of the battery cells.

[0463] Optionally, the fluorosulfonyl imide salt includes one or more of lithium bisfluorosulfonyl imide (LiFSI) and lithium bistrifluoromethanesulfonate (LiTFSI).

[0464] In some embodiments, the lithium salt comprises lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) is 0.5 mol / L to 1.0 mol / L. 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 (LiPF6) 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 (LiPF6) 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 (LiPF6) is 0.8 mol / L.

[0465] Optionally, the molar concentration ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate (LiPF6) is (2 to 5):10. Exemplarily, the molar concentration ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate (LiPF6) is 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10, 5:10, or a range of any two of the above values.

[0466] According to some embodiments of this application, this application also provides an electrical device, including a battery 2 from any of the above embodiments, wherein the battery 2 is used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize the battery 2.

[0467] Reference Figures 2 to 5 This application provides a battery 2, which includes a housing 20, a plurality of battery cell groups 100 and a plurality of heat exchange components 30, wherein the plurality of battery cell groups 100 and the plurality of heat exchange components 30 are housed within the housing 20.

[0468] The box 20 includes a first box wall 21, a second box wall 22 and a frame 23. The first box wall 21 and the second box wall 22 are arranged opposite each other in the vertical direction Z. The frame 23 connects the first box wall 21 and the second box wall 22. The first box wall 21 is located on the upper side of the second box wall 22. The first box wall 21, the second box wall 22 and the frame 23 enclose and form an accommodating space.

[0469] Each battery cell group 100 includes at least two battery cells 10 arranged along the first direction Y, and multiple battery cell groups 100 are arranged along the thickness direction X of the battery cells 10.

[0470] A heat exchanger 30 is provided between every two battery cell groups 100.

[0471] The battery cell 10 includes a housing 12, an electrode assembly 11, and a pressure relief mechanism 15. The housing 12 includes a first end wall 12a, a second end wall 12b, and a side wall 12c. The first end wall 12a is located on the side of the electrode assembly 11 facing the second housing wall 22, and the first end wall 12a is spaced apart from the second housing wall 22. The second end wall 12b is located on the side of the electrode assembly 11 facing the first housing wall 21 and is bonded to the first housing wall 21.

[0472] The sidewall 12c includes two first sidewalls 12d and two second sidewalls 12e. The two first sidewalls 12d are arranged opposite each other along the thickness direction X of the battery cell 10, and the two second sidewalls 12e are arranged opposite each other along a first direction Y perpendicular to the thickness direction X. Each second sidewall 12e connects to the two first sidewalls 12d. One of the first sidewalls 12d of the battery cell 10 is connected to and exchanges heat with the heat exchanger 30.

[0473] The pressure relief mechanism 15 is disposed on the first end wall 12a.

[0474] Under room temperature conditions, the charging time for a single battery cell 10 from 10% SOC to 80% SOC can be 5 min to 10.5 min.

[0475] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0476] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A battery, comprising: The box body includes a first box wall and a plurality of limiting beams connected to the first box wall; A battery cell is housed within a housing and located on the lower side of the first housing wall. The battery cell includes a housing, an electrode assembly, and a pressure relief mechanism. The housing is fixed to the first housing wall, and the electrode assembly is housed within the housing. The housing includes a first end wall located on the side of the electrode assembly away from the first housing wall. The pressure relief mechanism is disposed on the first end wall. A plurality of limiting beams are spaced apart along the thickness direction of the battery cell, and a plurality of battery cells are disposed between adjacent limiting beams. Specifically, under room temperature conditions, the charging time for the battery cell from 10% SOC to 80% SOC is 5 minutes to 10.5 minutes. In the thickness direction, the distance between two adjacent limiting beams is D1, and the sum of the dimensions of all electrode assemblies located between two adjacent limiting beams and stacked along the thickness direction is D2, where 85% ≤ D2 / D1 ≤ 92%; The electrode assembly includes a positive electrode, a negative electrode, and a separator between the positive and negative electrode. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material, which includes a lithium phosphate with an olivine structure. The negative electrode includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative active material, which includes a carbon-based material.

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

3. The battery according to claim 1 further includes a heat exchanger, the heat exchanger being used for heat exchange with the outer casing.

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

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

6. The battery according to claim 5, wherein, One of the first sidewalls of the battery cell is connected to the heat exchanger.

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

8. The battery according to claim 5, wherein, The heat exchanger is bonded to the first sidewall by a first adhesive layer.

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

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

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

12. The battery according to claim 1, wherein, The outer shell is bonded to the first box wall by a second adhesive layer.

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

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

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

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

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

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

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

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

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

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

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

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

25. The battery according to claim 22, wherein, The support member is connected to the adjacent limiting beam.

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

27. The battery according to claim 22, wherein, The support component has a cavity inside.

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

29. The battery according to any one of claims 1-27, further comprising a mounting beam disposed on the side of the first casing wall opposite to the battery cell.

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

31. The battery according to any one of claims 1-27, wherein, The battery cell also includes a sampling element disposed on the outer casing, the sampling element being used to collect the temperature of the outer casing.

32. The battery according to any one of claims 1-27, wherein, The expansion pressure of the battery cell in its thickness direction is 0.5MPa-2.4MPa.

33. The battery according to any one of claims 1-27, comprising a plurality of said battery cells and a plurality of busbars, said plurality of busbars electrically connecting the plurality of said battery cells; The plurality of busbar components includes at least one first busbar component, the first busbar component including a first busbar layer and a second busbar layer stacked and connected, the first busbar layer being electrically connected to at least two of the battery cells arranged along the thickness direction.

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

35. The battery according to claim 34, wherein, The first busbar layer includes a first busbar section, a second busbar section, and a first buffer section connecting the first busbar section and the second busbar section. The first busbar section and the second busbar section are disposed along the thickness direction and connected to different battery cells. The second busbar includes a first stacked portion, a second stacked portion, and a second buffer portion. The first stacked portion is stacked with the first busbar and connected by at least one of the bending portions. The second stacked portion is stacked with the second busbar and connected by at least one of the bending portions. The second buffer portion connects the first stacked portion and the second stacked portion.

36. The battery according to any one of claims 1-27, wherein, The single-sided coating weight of the negative electrode film is 90 mg / 1540 mm². 2 Up to 170mg / 1540mm 2 .

37. The battery according to claim 36, wherein, The single-sided coating weight of the negative electrode film is 110 mg / 1540 mm. 2 Up to 150mg / 1540mm 2 .

38. The battery according to any one of claims 1-27, wherein, The compaction density of the negative electrode film at 100% SOC of the battery cell is 1.15 g / cm³. 3 Up to 1.36 g / cm 3 .

39. The battery according to claim 38, wherein, The compaction density of the negative electrode film at 100% SOC of the battery cell is 1.25 g / cm³. 3 Up to 1.36 g / cm 3 .

40. The battery according to any one of claims 1-27, wherein, The porosity of the negative electrode is 27%-40%.

41. The battery according to any one of claims 1-27, wherein, The carbon-based material includes at least one of artificial graphite and natural graphite.

42. The battery according to any one of claims 1-27, wherein, The negative electrode active material also includes a silicon-based material, wherein the silicon element in the silicon-based material has a mass content of 0.3% to 10%.

43. The battery according to claim 42, wherein, The silicon-based material contains 1% to 6% silicon by mass in the negative electrode active material.

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

45. The battery according to any one of claims 1-27, wherein, The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, wherein the second negative electrode film layer is disposed between the first negative electrode film layer and the negative electrode current collector; The negative electrode active material includes a first negative electrode active material disposed on the first negative electrode film layer and a second negative electrode active material disposed on the second negative electrode film layer. The first negative electrode active material includes artificial graphite, and the second negative electrode active material includes one or more of artificial graphite, natural graphite, and silicon-based materials.

46. ​​The battery according to claim 45, wherein, The thickness ratio of the first negative electrode film to the second negative electrode film is 3:7 to 7:

3.

47. The battery according to claim 46, wherein, The thickness ratio of the first negative electrode film to the second negative electrode film is 4:6 to 6:

4.

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

49. The battery according to claim 45, wherein, The volume average particle size Dv50 of the first negative electrode active material is less than or equal to the volume average particle size Dv50 of the second negative electrode active material.

50. The battery according to claim 45, wherein, 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.

51. The battery according to claim 50, wherein, The volume average particle size Dv50 of the first negative electrode active material is 7.8 μm-11.3 μm; The volume average particle size Dv50 of the second negative electrode active material is 9.5 μm - 14.6 μm.

52. The battery according to any one of claims 1-27, wherein, The specific surface area of ​​the negative electrode active material is 0.5 m². 2 / g-3m 2 / g.

53. The battery according to claim 52, wherein, The specific surface area of ​​the negative electrode active material is 0.6 m². 2 / g-1.2m 2 / g.

54. The battery according to any one of claims 1-27, wherein, The olivine-structured lithium phosphate has the chemical formula LiFe. 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, M is selected from one or more of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb.

55. The battery according to any one of claims 1-27, wherein, The single-sided coating weight of the positive electrode film is 200 mg / 1540 mm². 2 -370mg / 1540mm 2 .

56. The battery according to claim 55, wherein, The single-sided coating weight of the positive electrode film is 240 mg / 1540 mm. 2 Up to 330mg / 1540mm 2 .

57. The battery according to any one of claims 1-27, wherein, The compaction density of the positive electrode film at 100% SOC of the battery cell is 2.50 g / cm³. 3 Up to 2.80 g / cm 3 .

58. The battery according to claim 57, wherein, The compaction density of the positive electrode film at 100% SOC of the battery cell is 2.55 g / cm³. 3 -2.70g / cm 3 .

59. The battery according to any one of claims 1-27, wherein, The porosity of the positive electrode is 25%-32%.

60. The battery according to any one of claims 1-27, wherein, The thickness of the positive electrode sheet is 0.13mm-0.2mm.

61. The battery according to any one of claims 1-27, wherein, The ratio of the thickness of the positive current collector to the thickness of the positive electrode film is 0.05-0.

3.

62. The battery according to any one of claims 1-27, wherein, The volume average particle size of the positive electrode active material satisfies 1µm≤Dv50≤2µm and 0.4µm≤Dv10≤0.7µm.

63. The battery according to any one of claims 1-27, wherein, The battery cell includes an electrolyte contained within the casing.

64. The battery according to claim 63, wherein, The electrolyte has a conductivity of 15 mS / cm to 20 mS / cm at room temperature.

65. The battery according to claim 63, wherein, The electrolyte includes an organic solvent, which includes one or more of carbonate solvents and carboxylic acid ester solvents.

66. The battery according to claim 65, wherein, The carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

67. The battery according to claim 65, wherein, The carboxylic acid ester comprises R1-COO-R2, wherein R1 and R2 are independently selected from alkyl groups having 1-5 carbon atoms or haloalkyl groups having 1-5 carbon atoms.

68. The battery according to claim 63, wherein, The electrolyte comprises a lithium salt, which includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is from 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) is from 0.5 mol / L to 1.0 mol / L.

69. The battery according to claim 63, wherein, The density ρ of the electrolyte at room temperature satisfies: 1.05 g / mL ≤ ρ ≤ 1.35 g / mL.

70. An electrical device comprising a battery according to any one of claims 1-69, the battery being used to provide electrical energy.

Images