Batteries, energy storage devices and energy storage systems

Abstract

The present application provides a battery, an energy storage device, and an energy storage system. The battery of the present application includes: an electrode assembly, the electrode assembly including a positive electrode plate, a separator, and a negative electrode plate; an electrolyte, the electrolyte including an electrolyte salt and an organic solvent, the organic solvent including a cyclic carbonate and a chain carbonate, the mass ratio of the cyclic carbonate to the chain carbonate being A; and a shell assembly, the shell assembly including a first end cap assembly, a shell, and a second end cap assembly, the first end cap assembly including a connected first top cap and a first explosion-proof valve, the first top cap being electrically connected to the positive electrode plate; the second end cap assembly including a second top cap, a negative electrode column, and a second explosion-proof valve, the negative electrode column being electrically connected to the negative electrode plate; the area ratio of the first explosion-proof valve to the second explosion-proof valve being B; wherein the battery satisfies the relationship: 2.23≤B / A≤17.65.

Description

Technical Field

[0001] The present application relates to the field of energy storage, and specifically to a battery, an energy storage device, and an energy storage system. Background Art

[0002] With the continuous development of lithium-ion battery technology, lithium-ion batteries have advantages over other types of batteries such as lead-acid and nickel-cadmium batteries, such as high specific capacity, no memory effect, high operating voltage, fast charging speed, wide operating temperature range, long cycle life, small size, and light weight. Currently, lithium-ion batteries are widely used in mobile phones, laptops, electric vehicles, energy storage cabinets and other fields, and their application range is becoming increasingly wider.

[0003] With the development of the energy storage industry, higher requirements are placed on the dynamic performance of lithium-ion batteries. However, after the dynamic performance is improved, the gas production of batteries, especially cylindrical batteries, during the charging and discharging process increases, which will reduce the safety performance of the batteries. Summary of the Invention

[0004] The embodiments of the present application provide a battery having high dynamic performance and safety performance.

[0005] In a first aspect, an embodiment of the present application provides a battery comprising:

[0006] An electrode assembly, comprising a positive electrode sheet, a separator, and a negative electrode sheet;

[0007] an electrolyte, the electrolyte comprising an electrolyte salt and an organic solvent, the organic solvent comprising a cyclic carbonate and a chain carbonate, the mass ratio of the cyclic carbonate to the chain carbonate being A; and

[0008] A shell assembly, the shell assembly comprising a first end cap assembly, a shell and a second end cap assembly, the shell being a hollow structure, the first end cap assembly and the second end cap assembly being respectively disposed at opposite ends of the shell, the first end cap assembly, the shell and the second end cap assembly enclosing a receiving chamber, the first end cap assembly comprising a connected first top cap and a first explosion-proof valve, the first top cap being disposed around the periphery of the first explosion-proof valve, the first top cap being electrically connected to the positive electrode sheet; the second end cap assembly comprising a second top cap, a negative electrode column and a second explosion-proof valve, the second top cap being disposed around the second explosion-proof valve, the negative electrode column being disposed through the second top cap and protruding from a side of the second top cap facing away from the shell, the negative electrode column being electrically connected to the negative electrode sheet; the area ratio of the first explosion-proof valve to the second explosion-proof valve being B;

[0009] The battery satisfies the relationship: 2.23≤B / A≤17.65.

[0010] Furthermore, the mass ratio A of the cyclic carbonate to the linear carbonate is in the range of 0.17≤A≤0.67.

[0011] Furthermore, the cyclic carbonate includes ethylene carbonate, the chain carbonate includes ethyl methyl carbonate and dimethyl carbonate, and the mass ratio A1 of the ethyl methyl carbonate to the dimethyl carbonate is in the range of 0.5≤A1≤2.

[0012] Furthermore, the range of the area ratio B between the first explosion-proof valve and the second explosion-proof valve is: 1.5≤B≤3.

[0013] Furthermore, the area b1 of the first explosion-proof valve is 120 mm 2 ≤b1≤240mm 2 The area b2 of the second explosion-proof valve is 90mm 2 ≤b2≤160mm 2 .

[0014] Furthermore, the electrolyte salt includes lithium hexafluorophosphate and lithium bisfluorosulfonyl imide, and the mass ratio of the lithium bisfluorosulfonyl imide to the lithium hexafluorophosphate is G; and the battery also satisfies the relationship: 0.03≤G / B≤9.87.

[0015] Furthermore, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is in the range of 0.1≤G≤14.8.

[0016] Furthermore, the battery is cylindrical, and the ratio L / D of the length L of the battery to the diameter D of the battery is in the range of: 2.43≤L / D≤5.98.

[0017] In a second aspect, an embodiment of the present application further provides a battery, comprising:

[0018] An electrode assembly, comprising a positive electrode sheet, a separator, and a negative electrode sheet;

[0019] an electrolyte solution comprising an electrolyte salt, wherein the electrolyte salt comprises lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the mass ratio of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is G; and

[0020] A shell assembly, the shell assembly comprising a first end cap assembly, a shell and a second end cap assembly, the shell being a hollow structure, the first end cap assembly and the second end cap assembly being respectively disposed at opposite ends of the shell, the first end cap assembly, the shell and the second end cap assembly enclosing a receiving chamber, the receiving chamber being used to receive the electrode assembly and the electrolyte; the first end cap assembly comprising a first top cap and a first explosion-proof valve, the first top cap being disposed around the periphery of the first explosion-proof valve, the first top cap being electrically connected to the positive electrode sheet; the second end cap assembly comprising a second top cap, a negative electrode column and a second explosion-proof valve, the second top cap being disposed around the periphery of the second explosion-proof valve, the negative electrode column being disposed through the second top cap and protruding from a side of the second top cap facing away from the shell, the negative electrode column being electrically connected to the negative electrode sheet; the area ratio of the first explosion-proof valve to the second explosion-proof valve being B;

[0021] The battery satisfies the relationship: 0.03≤G / B≤9.87.

[0022] Furthermore, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is in the range of 0.1≤G≤14.8.

[0023] Furthermore, the range of the area ratio B between the first explosion-proof valve and the second explosion-proof valve is: 1.5≤B≤3.

[0024] Furthermore, the area of ​​the first explosion-proof valve is b1 and the range is 120mm 2 ≤b1≤240mm 2 The second explosion-proof valve area b2 range is 90mm 2 ≤b2≤160mm 2 .

[0025] Furthermore, the shell assembly is cylindrical, the central axis of the shell assembly extends along the arrangement direction of the first end cover assembly, the shell and the second end cover assembly, and the length L of the shell assembly and the diameter D of the shell assembly satisfy the relationship: 2.43≤L / D≤5.98.

[0026] In a third aspect, an embodiment of the present application further provides an energy storage device, comprising:

[0027] cabinet; and

[0028] A plurality of batteries according to the embodiments of the present application are housed in the box.

[0029] In a fourth aspect, an embodiment of the present application further provides an energy storage system, comprising: an electric energy conversion device and the energy storage device described in the embodiment of the present application, the electric energy conversion device being electrically connected to the energy storage device, the electric energy conversion device being used to convert other forms of energy into electric energy, and the energy storage device being used to store the electric energy.

[0030] In the battery of the embodiment of the present application, the ratio B / A of the area ratio B of the first explosion-proof valve and the second explosion-proof valve to the mass ratio A of the cyclic carbonate to the chain carbonate is designed to be in the range of 2.23≤B / A≤17.65. In this way, the ratio of the cyclic carbonate to the chain carbonate in the battery can be within an appropriate range, so that the electrolyte salt of the electrolyte has a high dissociation ability and good low-temperature performance, and has high wettability for the electrode pole piece, so that the battery has good dynamic performance and cycle performance; at the same time, the gas production is increased due to the improvement of battery dynamics. By reasonably configuring the area ratio of the first explosion-proof valve and the second explosion-proof valve, the risk of thermal runaway pressure relief can be better reduced, and the battery can have good pressure relief capacity when overcharged and exploded, thereby having high safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 Schematic diagram of the structure of a battery according to an embodiment of the present application.

[0033] Figure 2 Schematic diagram of the explosion structure of a battery according to an embodiment of the present application.

[0034] Figure 3 2 is a schematic structural diagram of a battery according to another embodiment of the present application from another perspective.

[0035] Figure 4 2 is a schematic diagram of an exploded structure of a battery according to an embodiment of the present application from another perspective.

[0036] Figure 5 This is a schematic diagram of the structure of the electrode assembly after winding according to one embodiment of the present application.

[0037] Figure 6 It is a structural schematic diagram of the positive electrode plate of an embodiment of the present application.

[0038] Figure 7 Schematic diagram of the structure of the negative electrode sheet of one embodiment of the present application.

[0039] Figure 8 It is a structural diagram of an energy storage device according to an embodiment of the present application.

[0040] Figure 9 This is a structural block diagram of an energy storage system according to an embodiment of the present application.

[0041] Figure 10 This is an application scenario diagram of the energy storage system of one embodiment of the present application.

[0042] Description of reference numerals:

[0043] 100-battery, 10-electrode assembly, 11-positive electrode plate, 111-positive current collector, 112-positive electrode active layer, 12-diaphragm, 13-negative electrode plate, 131-negative current collector, 132-negative electrode active layer, 20-housing assembly, 21-first end cover assembly, 211-first top cover, 212-first explosion-proof valve, 22-housing, 23-second end cover assembly, 231-second top cover, 232-negative electrode column, 233-second explosion-proof valve, 24-receiving chamber, 200-energy storage device, 210-housing, 300-energy storage system, 310-electric energy conversion device. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0046] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0047] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0048] With the development of the energy storage industry, higher requirements are placed on the dynamic performance of lithium-ion batteries. However, after the dynamic performance is improved, the gas production of batteries, especially cylindrical batteries, during the charging and discharging process increases, which will reduce the safety performance of the batteries.

[0049] Cylindrical batteries have a high yield rate and the cost of assembling them into energy storage modules with multiple batteries is low. They have obvious advantages in applications in electric vehicles, household storage and energy storage power stations.

[0050] However, due to differences in the core structure, cylindrical batteries are prone to shortcomings such as insufficient wetting, poor kinetics, easy gas production, lithium deposition, and rapid deterioration of cycle life. High-kinetic system electrolytes are needed to compensate for this, but high-kinetic system electrolytes contain a high proportion of low-boiling point solvents, and the solvents themselves are easily vaporized and produce gas, and their safety performance will deteriorate under high temperature and overcharge.

[0051] See Figures 1 to 5 , an embodiment of the present application provides a battery 100, which includes an electrode assembly 10, an electrolyte and a shell assembly 20. The electrode assembly 10 includes a positive electrode plate 11, a separator 12 and a negative electrode plate 13. The electrolyte includes an electrolyte salt and an organic solvent, and the organic solvent includes a cyclic carbonate and a chain carbonate, and the mass ratio of the cyclic carbonate to the chain carbonate is A. The shell assembly 20 includes a first end cover assembly 21, a shell 22 and a second end cover assembly 23. The shell 22 is a hollow structure. The first end cover assembly 21 and the second end cover assembly 23 are respectively arranged at opposite ends of the shell 22. The first end cover assembly 21, the shell 22 and the second end cover assembly 23 enclose a receiving cavity 24, and the receiving cavity 24 is used to receive the electrode assembly 10 and the electrolyte; the first end cover assembly 21 includes a first top cover 211 and a first explosion-proof valve 212 connected to each other. The first top cover 211 is arranged around the outer periphery of the first explosion-proof valve 212. The first top cover 211 is electrically connected to the positive electrode sheet 11. The second end cover assembly 23 includes a second top cover 231, a negative electrode column 232 and a second explosion-proof valve 233. The second top cover 231 is arranged around the second explosion-proof valve 233. The negative electrode column 232 is penetrated by the second top cover 231 and protrudes from the side of the second top cover 231 away from the shell 22. The negative electrode column 232 is electrically connected to the negative electrode sheet 13. The area ratio of the first explosion-proof valve 212 to the second explosion-proof valve 233 is B. The battery 100 satisfies the relationship: 2.23≤B / A≤17.65.

[0052] The battery 100 of the embodiment of the present application may be, but is not limited to, at least one of a lithium-ion battery 100 , a sodium-ion battery 100 , and the like.

[0053] It should be noted that the first top cover 211, the shell 22 and the second top cover 231 are connected, the second top cover 231 is connected to the second explosion-proof valve 233, and the negative electrode column 232 is insulated from the second top cover 231, so that the positive electrode sheet 11 is insulated from the negative electrode sheet 13.

[0054] It should be noted that the positive electrode sheet 11 , the separator 12 and the negative electrode sheet 13 are stacked in sequence and then wound together to form the wound electrode assembly 10 .

[0055] Optionally, the housing 22 and the first top cover 211 are an integral structure. In other words, the housing 22 and the first top cover 211 are two different parts of the same component.

[0056] Specifically, the ratio B / A of the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 to the mass ratio A of the cyclic carbonate to the linear carbonate can be, but is not limited to, 2.23, 2.5, 3.0, 3.5, 4.0, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 17.65.

[0057] In this embodiment, when B / A is too large, the area ratio B between the first explosion-proof valve 212 and the second explosion-proof valve 233 is too large, and the mass ratio A of the cyclic carbonate to the chain carbonate is too small. If the mass ratio A of the cyclic carbonate to the chain carbonate is too small, the gas production of the battery 100 during overcharging will increase, and the gas produced will mainly be flammable gases such as CH4 and C2H6. The increase in the production of flammable gas requires the battery 100 to have better pressure relief capability and higher pressure relief speed. If the area ratio B between the first explosion-proof valve 212 and the second explosion-proof valve 233 is too large, the pressure relief capability of the second explosion-proof valve 233 will be too small, making it difficult to relieve pressure in time during explosion, thereby reducing the safety performance of the battery 100. If B / A is too small, the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is too small, and the mass ratio A of the cyclic carbonate to the chain carbonate is too large; when the mass ratio A of the cyclic carbonate to the chain carbonate is too large, the gas production of the battery 100 during overcharging will decrease, and the pressure relief capacity requirements of the first explosion-proof valve 212 and the second explosion-proof valve 233 will be relatively reduced. However, if B is too small, the area of ​​the second explosion-proof valve 233 is too large, which increases the design difficulty of the negative electrode 232, the second top cover 231 and the second explosion-proof valve 233. In addition, the mass ratio A of the cyclic carbonate to the chain carbonate is too large, which increases the viscosity of the electrolyte and increases the low-temperature freezing point of the electrolyte, thereby reducing the room temperature cycle performance of the battery 100. In summary, when the ratio B of the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 to the mass ratio A of the cyclic carbonate to the chain carbonate is in the range of 2.23≤B / A≤17.65, the ratio of the cyclic carbonate to the chain carbonate in the battery 100 can be within an appropriate range, so that the electrolyte salt of the electrolyte has a higher dissociation ability and better low-temperature performance, and has a higher wettability to the electrode pole piece, so that the battery 100 has better dynamic performance and cycle performance; at the same time, the gas production brought about by the improvement of the dynamics of the battery 100 increases, and by reasonably configuring the area ratio of the first explosion-proof valve 212 and the second explosion-proof valve 233, the risk of thermal runaway pressure relief can be better reduced, and the battery 100 can have better pressure relief capacity when overcharged and exploded, thereby having higher safety performance.

[0058] In some embodiments, the mass ratio A of the cyclic carbonate to the linear carbonate is in the range of 0.17≤A≤0.67.

[0059] Specifically, the mass ratio A of the cyclic carbonate to the linear carbonate may be, but is not limited to, 0.17, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.38, 0.4, 0.43, 0.45, 0.48, 0.5, 0.53, 0.55, 0.58, 0.6, 0.63, 0.65, 0.67, etc.

[0060] In this embodiment, the cyclic carbonate has a high dielectric constant and high ionic conductivity, and can form a stable SEI film on the surface of the negative electrode plate 13, but its viscosity is relatively high. Chain carbonates have lower viscosity than cyclic carbonates, better electrochemical stability, and can improve the low-temperature performance of the electrolyte. If the mass ratio A of the cyclic carbonate to the chain carbonate is too small, the viscosity of the electrolyte is reduced, which is beneficial for improving the wettability of the electrolyte to the electrode assembly 10, thereby improving the cycle performance and kinetic performance of the battery 100. However, the reduction reaction of the chain carbonate is the main cause of gas production in the battery 100. If the mass ratio A of the cyclic carbonate to the chain carbonate is too small, the gas production during the overcharging process of the battery 100 will increase. The gas produced is mainly flammable gases such as CH4 and C2H6. The increase in the production of flammable gas increases the probability of thermal runaway such as explosion and fire in the battery 100, reducing the safety performance of the battery 100. As the mass ratio A of the cyclic carbonate to the chain carbonate increases, that is, the content of the cyclic carbonate increases and the content of the chain carbonate decreases, the total gas production in the battery 100 gradually decreases when the battery 100 is overcharged; in addition, the main types of gas produced are gases such as CO2, H2, CO, and the output of the non-combustible gas CO2 increases, which reduces the risk of thermal runaway such as fire in the battery 100 and improves the safety performance of the battery 100; however, the increase in the cyclic carbonate content increases the viscosity of the electrolyte and increases the low-temperature freezing point of the electrolyte, thereby reducing the room temperature cycle performance of the battery 100. When the mass ratio A of the cyclic carbonate to the linear carbonate is in the range of 0.17≤A≤0.67, the electrolyte can have a more suitable viscosity, a lower low-temperature freezing point and higher room-temperature cycle performance. The battery 100 can also produce less gas during overcharging, and the combustible gas in the produced gas is also reduced. In conjunction with the design of the explosion-proof valve, the battery 100 is less prone to thermal runaway and has higher safety performance.

[0061] In some embodiments, the cyclic carbonate includes ethylene carbonate (EC), the chain carbonate includes ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC), and the mass ratio A1 of the ethyl methyl carbonate to the dimethyl carbonate is in the range of 0.5≤A1≤2.

[0062] Specifically, the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate may be, but is not limited to, 0.5, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, etc.

[0063] In this embodiment, the greater the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate in the electrolyte, the lower the low-temperature freezing point of the electrolyte. However, if the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate is too large, the high-temperature side reactions of the battery 100 will be aggravated, which is not conducive to the cycle performance of the battery 100. If the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate is too small, the low-temperature freezing point of the electrolyte will increase, which is not conducive to the cycle performance of the battery 100, and the overcharge resistance of the battery 100 will be reduced, increasing the risk of explosion when the battery 100 is overcharged. When the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate is in the range of 0.5≤A1≤2, the battery 100 has good low-temperature cycle performance and high-temperature cycle performance.

[0064] Optionally, the cyclic carbonate may also include propylene carbonate (abbreviated as PC).

[0065] Optionally, the organic solvent further comprises at least one of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, γ-butyrolactone, 2,2-difluoroethyl acetate, methyl formate, and ethyl fluoroacetate.

[0066] In the organic solvent, the total mass of the cyclic carbonate and the linear carbonate accounts for 80% to 100% of the organic solvent, for example, 80%, 83%, 85%, 88%, 90%, 93%, 95%, 98%, 100%, etc.

[0067] In some embodiments, the electrolyte salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, and the mass ratio of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is G. The battery 100 further satisfies the relationship: 0.03≤G / B≤9.87.

[0068] Specifically, the ratio G of the mass ratio of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate to the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 may be, but is not limited to, 0.03, 0.05, 0.1, 0.2, 0.3, 0.5, 0.8, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 9.87, etc.

[0069] In this embodiment, if G / B is too small, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is too small, and the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is too large. If G is too small, the thermal stability of the electrolyte is reduced, and the heat generated by the decomposition of lithium hexafluorophosphate increases when the battery 100 is overcharged. The decomposition heat and gas production cause the air pressure inside the battery 100 to increase sharply. If the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is too large at this time, that is, the difference in pressure relief capacity between the first explosion-proof valve 212 and the second explosion-proof valve 233 is too large, then the pressure relief rate of the second explosion-proof valve 233 with a smaller area is too low, thereby reducing the safety performance of the battery 100. The negative electrode column 232 of the battery 100 protrudes from the side of the second top cover 231 away from the shell 22. Therefore, during assembly and use, the second end cover assembly 23 with the negative electrode column 232 is usually facing upward and the first end cover assembly 21 is facing downward; as G increases, the dissociation degree of the electrolyte salt (i.e., lithium salt) can be improved, thereby improving the dynamic performance of the battery 100. However, when G / B is too large, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is too large, and the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is too small. When G is too large, the content of lithium bis(fluorosulfonyl)imide in the electrolyte is too high, which increases the total gas production when the battery 100 is overcharged, and the heavier gas in the gas production gathers on the side of the first explosion-proof valve 212, causing the first explosion-proof valve 212 to bear greater pressure. If B is too small at this time, the area of ​​the first explosion-proof valve 212 is too small, which reduces the pressure relief rate of the first explosion-proof valve 212 and increases the risk of overcharging the battery 100. In summary, when the ratio G of the mass ratio G of lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate and the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is in the range of 0.03≤G / B≤9.87, the first explosion-proof valve 212 and the second explosion-proof valve 233 can have a suitable pressure relief speed when the battery 100 is overcharged, thereby improving the safety performance of the battery 100, and at the same time, the battery 100 can have higher dynamic performance and cycle performance.

[0070] In some embodiments, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is in the range of 0.1≤G≤14.8.

[0071] Specifically, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate may be, but is not limited to, 0.1, 0.3, 0.5, 1, 2, 3, 5, 6, 8, 10, 11, 12, 13, 14, or 14.8.

[0072] When the battery 100 is overcharged, the electrolyte is rapidly consumed and vaporized, allowing the gas generated in the battery 100 to escape from the first explosion-proof valve 212 and the second explosion-proof valve 233. In this embodiment, compared to using only lithium hexafluorophosphate as the electrolyte salt, the combination of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate can increase the degree of dissociation of the electrolyte salt (i.e., lithium salt) and improve the kinetic performance of the battery 100. When the mass ratio G of lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is too small, the proportion of lithium hexafluorophosphate in the electrolyte salt is high, which reduces the thermal stability of the electrolyte, increases the risk of heat generation from the decomposition of lithium hexafluorophosphate, and reduces the safety performance of the battery 100. When the mass ratio G of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is too high, the content of lithium bis(fluorosulfonyl)imide in the electrolyte is too high, causing an increase in the total amount of gas generated when the battery 100 is overcharged, increasing the risk of overcharging. High temperatures also corrode the aluminum foil (i.e., the positive current collector of the positive electrode sheet 11), reducing the adhesion between the positive current collector of the positive electrode sheet 11 and the positive active layer, potentially causing the risk of detachment, and significantly reducing the cycle life of the battery 100. When the mass ratio G of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is within the range of 0.1≤G≤14.8, the battery 100 can have higher dynamic performance and cycle performance.

[0073] Optionally, in the electrolyte, the molar concentration M of the electrolyte salt is in the range of 0.8 mol / L≤M≤1.2 mol / L. In the electrolyte, the electrolyte salinity M may be, but is not limited to, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, and the like. If the electrolyte salt M is too low, the concentration of free ions in the electrolyte is too low, which reduces the conductivity of the electrolyte and thus reduces the kinetic performance of the battery 100; if the electrolyte salt is too high, a portion of the electrolyte salt is likely to remain undissociated, which increases the viscosity of the electrolyte, thereby reducing the conductivity of the electrolyte and also reducing the kinetic performance of the battery 100. When the electrolyte salt M is in the range of 0.8 mol / L≤M≤1.2 mol / L, the electrolyte can have a higher conductivity, thereby allowing the battery 100 to have better kinetic performance.

[0074] In some embodiments, the electrolyte further includes a sulfur-containing additive. The sulfur-containing additive can form lithium sulfate or lithium alkyl sulfate in the positive electrode plate 11, further stabilizing the solid electrolyte interface (SEI) film of the positive electrode plate 11 and making the SEI film thinner, thereby effectively reducing the impedance of the positive electrode plate 11 and thereby reducing the heat generated by the high temperature of the positive electrode plate 11 and improving the safety performance of the battery 100.

[0075] Optionally, the sulfur-containing additive may be, but is not limited to, a positive electrode sulfur-containing additive.

[0076] Optionally, in the electrolyte, the mass fraction w1 of the sulfur-containing additive is in the range of 0.1 wt% ≤ w1 ≤ 1 wt%. Specifically, in the electrolyte, the mass fraction w1 of the sulfur-containing additive may be, but is not limited to, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, etc. If the mass fraction w1 of the sulfur-containing additive in the electrolyte is too low, the stability of the interface film of the positive electrode sheet 11 is limited, and the safety performance of the battery 100 cannot be effectively improved. If the mass fraction w1 of the sulfur-containing additive in the electrolyte is too high, the sulfur-containing additive easily decomposes and produces acid at high temperatures, destroying the interface film of the positive electrode sheet 11. This causes the positive active layer of the positive electrode sheet 11 to directly contact the electrolyte, increasing side reactions between the positive active layer and the electrolyte, thereby increasing electrolyte consumption and reducing the cycle capacity retention rate of the battery 100. When the mass fraction of the sulfur-containing additive in the electrolyte is 0.1wt%≤w1≤1wt%, the safety performance of the battery 100 can be better improved while maintaining a high cycle capacity retention rate.

[0077] In some embodiments, the sulfur-containing additive includes at least one of bis(vinylsulfone)methane, methylene disulfonate (MMDS), ethylene sulfate (DTD), propene sultone (PST), butane sultone (BS), and propene sulfite (PS). In this embodiment, the use of these sulfur-containing additives can better stabilize the interface film of the positive electrode plate 11, reduce the impedance of the positive electrode plate 11, reduce the high-temperature heat generation of the positive electrode plate 11, and improve the safety performance of the battery 100. In addition, these substances are less likely to decompose and produce acid when the battery 100 is exposed to high temperatures, which can better reduce the consumption of electrolyte at high temperatures, thereby maintaining a high cycle capacity retention rate of the battery 100.

[0078] Optionally, the electrolyte further includes a film-forming additive. When the electrolyte is applied to the lithium-ion battery 100 , the film-forming additive can be used to promote the formation of an interface film of at least one of the positive electrode sheet 11 and the negative electrode sheet 13 and maintain the stability of the interface film.

[0079] Optionally, the film-forming additive includes at least one of fluoroethylene carbonate (FEC), diethylene sulfate (DTD), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), sulfur tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, adiponitrile, succinonitrile, and 1,3,6-hexanetrinitrile.

[0080] Optionally, the mass fraction of the film-forming additive ranges from 1.5% to 3%. Specifically, the mass fraction of the film-forming additive may be, but is not limited to, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, etc.

[0081] In some embodiments, the area of ​​the first explosion-proof valve 212 is greater than the area of ​​the second explosion-proof valve 233 , and the range of the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is: 1.5≤B≤3.

[0082] Specifically, the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 can be, but is not limited to, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.1, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, etc.

[0083] For the cylindrical battery 100, the surface of its first end cover assembly 21 (i.e., the end cover electrically connected to the positive electrode plate 11) facing away from the shell 22 is flat, and the second end cover assembly 23 (i.e., the end cover electrically connected to the negative electrode plate 13) is provided with a negative electrode column 232 on the side facing away from the shell 22. Therefore, when in use, the first end cover assembly 21 of the battery 100 is facing downward, and the second end cover assembly 23 of the battery 100 is set upward. When the battery 100 is overcharged, most of the electrolyte in the outer shell assembly 20 is consumed. Among the gases generated in the battery 100, the heavier gases will sink and gather at the position of the first end cover assembly 21 (i.e., the first explosion-proof valve 212), and the lighter gases will float up and gather at the position of the second end cover assembly 23 (i.e., the second explosion-proof valve 233), so that the gas pressure exerted on the second explosion-proof valve 233 is greater than the gas pressure exerted on the first explosion-proof valve 212. In this embodiment, by making the area of ​​the first explosion-proof valve 212 larger than the area of ​​the second explosion-proof valve 233, the first explosion-proof valve 212 has a better pressure relief capability than the second explosion-proof valve 233. When the battery 100 is overcharged and the first explosion-proof valve 212 and the second explosion-proof valve 233 explode, the first explosion-proof valve 212 can release the gas pressure faster than the second explosion-proof valve 233, thereby improving the safety performance of the battery 100 when it is overcharged. However, when the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is too small, the second explosion-proof valve 233 is too large, which increases the difficulty of designing the second top cover 231 and the negative electrode column 232. If the area of ​​the first explosion-proof valve 212 is too small (positive electrode side explosion-proof valve), when the battery 100 is overcharged, the first explosion-proof valve 212 side cannot be depressurized in time. In addition, it is difficult to match the application scenario with a large gas production when the ratio of cyclic carbonate to chain carbonate is low and the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is low. In addition, when the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is too large, the first explosion-proof valve 212 is too large, and the space reserved for the first top cover 211 is too small, so that the first explosion-proof valve 212 and the first top cover 211 do not meet the design requirements. In addition, the pressure resistance of the first explosion-proof valve 212 is reduced, which may cause the first explosion-proof valve 212 to explode prematurely, affecting the normal use of the battery 100; the second explosion-proof valve 233 is too small, and the pressure release rate of the second explosion-proof valve 233 is slow when it explodes. The speed of gas release at the first explosion-proof valve 212 of the battery 100 is too slow, and the pressure cannot be released in time, which increases the risk of explosion of the battery 100. It is difficult to match the application scenario with a large gas production when the ratio of cyclic carbonate to chain carbonate is low and the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is low.When the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is in the range of 1.5≤B≤3, when the first explosion-proof valve 212 and the second explosion-proof valve 233 explode, the gas is released faster from the first explosion-proof valve 212 of the battery 100, and the pressure resistance of the first explosion-proof valve 212 and the second explosion-proof valve 233 do not differ too much, so that the battery 100 will not explode prematurely and affect normal use.

[0084] In some embodiments, the area b1 of the first explosion-proof valve 212 is 120 mm 2 ≤b1≤240mm 2 The area b2 of the second explosion-proof valve 233 is 90mm 2 ≤b2≤160mm 2 .

[0085] Specifically, the area b1 of the first explosion-proof valve 212 may be, but is not limited to, 120 mm. 2 , 140mm 2 , 150mm 2 , 160mm 2 , 180mm 2 , 200mm 2 , 220mm 2 , 240mm 2 If the area b1 of the first explosion-proof valve 212 is too small, the pressure relief capacity of the first explosion-proof valve 212 is reduced, and the safety performance of the battery 100 during overcharge is reduced; if the area b1 of the first explosion-proof valve 212 is too large, the area of ​​the first top cover 211 needs to be increased, which makes the battery 100 thicker and the number of turns of the electrode assembly 10 more. During the charge and discharge cycle, the part of the area near the inner side of the wound electrode assembly 10 is subjected to excessive extrusion stress during the lithium insertion and expansion process. The electrolyte in this part of the electrode assembly 10 is easily squeezed out, causing the part of the electrode assembly 10 near the winding center to be in a liquid-deficient state, which increases the gas production of the battery 100, thereby reducing the safety performance of the battery 100, and making lithium deposition more likely to occur, worsening the cycle performance of the battery 100.

[0086] Specifically, the area b2 of the second explosion-proof valve 233 may be, but is not limited to, 90 mm. 2 , 100mm 2 , 110mm 2 , 120mm 2 , 140mm 2 , 150mm 2 , 160mm 2If the area b1 of the second explosion-proof valve 233 is too small, the pressure relief capacity of the second explosion-proof valve 233 is reduced, and the safety performance of the battery 100 during overcharge is reduced; if the area b1 of the second explosion-proof valve 233 is too large, the area of ​​the second top cover 231 needs to be increased, which makes the battery 100 thicker and the number of turns of the electrode assembly 10 is increased. During the charge and discharge cycle, the part of the area near the inner side of the wound electrode assembly 10 is subjected to excessive extrusion stress during the lithium insertion and expansion process. The electrolyte in this part of the electrode assembly 10 is easily squeezed out, causing the part of the electrode assembly 10 near the winding center to be in a liquid-deficient state, resulting in an increase in the gas production of the battery 100, thereby reducing the safety performance of the battery 100 and making lithium deposition more likely to occur, worsening the cycle performance of the battery 100; in addition, the design difficulty of the negative electrode 232 and the second explosion-proof valve 233 is increased.

[0087] Please see again Figure 2 In some embodiments, the battery 100 is cylindrical (i.e., a cylindrical battery 100), and the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 is in the range of 2.43≤L / D≤5.98. In other words, the aspect ratio L / D of the battery 100 is in the range of 2.43≤L / D≤5.98.

[0088] It can be understood that the outer shell assembly 20 is cylindrical, the shell 22 is a cylindrical structure, and the first end cover assembly 21 and the second end cover assembly 23 are circular structures.

[0089] Specifically, the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 may be, but is not limited to, 2.43, 2.6, 2.8, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 5.98, etc.

[0090] In this embodiment, the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 is too small, so the electrode assembly 10 of the battery 100 is wound a large number of times and the electrode assembly 10 is thicker. During the charge and discharge cycle, a part of the area near the inner side of the wound electrode assembly 10 is subjected to excessive extrusion stress during the lithium insertion and expansion process. The electrolyte in this part of the electrode assembly 10 is easily squeezed out, causing the part of the electrode assembly 10 near the winding center to be in a liquid-deficient state, which increases the gas production of the battery 100, thereby reducing the safety performance of the battery 100, and making lithium plating more likely to occur, worsening the cycle performance of the battery 100. The cylindrical battery 100 is usually injected from one end of the cylinder. After injection, it first enters the gap between the shell component 20 and the wound electrode component 10, and then gradually infiltrates the entire electrode component 10 from the outer ring of the electrode component 10 and the two ends of the electrode component 10 (the end close to the first end cover component 21 and the end close to the second end cover component 23). When the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 is too large, the design of the electrode component 10 is too long, and the path of the electrolyte from the two ends of the electrode component 10 to the middle is too long, so that the electrolyte flow along the battery 100 is too long. Insufficient or insufficient wetting of the electrode assembly 10 near the middle of the length of the battery 100 can easily form an unwetted zone in the middle of the length of the battery 100, making lithium deposition more likely in this zone, reducing the cycle performance of the battery 100 and causing the battery 100 to prematurely stop cycling. Furthermore, this increases the likelihood of side reactions between the unwetted zone and the solvent in the electrolyte, which in turn increases gas production. The exhaust path is longer, and the pressure within the battery 100 is released too slowly, preventing it from being discharged in a timely manner. This increases the internal pressure of the battery 100 and increases the risk of explosion. When the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 is in the range of 2.43 ≤ L / D ≤ ​​5.98, the entire electrolyte can have good wettability with the electrode assembly 10, making it less prone to gas production. This results in the battery 100 having better safety performance and better cycle performance.

[0091] See Figure 6 Optionally, the positive electrode sheet 11 includes a positive electrode current collector 111 and a positive electrode active layer 112, wherein the positive electrode active layer 112 is disposed on the surface of the positive electrode current collector 111. It is understood that the positive electrode active layer 112 may cover one surface or two opposite surfaces of the positive electrode current collector 111.

[0092] Optionally, the positive electrode current collector 111 may be, but is not limited to, an aluminum sheet.

[0093] Optionally, the positive electrode active layer 112 includes a positive electrode active material, a positive electrode conductor, a positive electrode binder, and a positive electrode thickener.

[0094] Optionally, the positive electrode active material may be, but is not limited to, lithium iron phosphate.

[0095] Optionally, the diaphragm 12 may be, but is not limited to, at least one of a polypropylene film (PP film for short), a polyethylene film (PE film for short), a ceramic diaphragm 12 , and the like.

[0096] Optionally, the thickness of the diaphragm 12 is 14 μm to 18 μm. Specifically, the thickness of the diaphragm 12 may be, but is not limited to, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, and 18 μm.

[0097] See Figure 7 Optionally, the negative electrode sheet 13 includes a negative electrode current collector 131 and a negative electrode active layer 132, and the negative electrode active layer 132 is disposed on the surface of the negative electrode current collector 131. It can be understood that the negative electrode active layer 132 can cover one surface or two opposite surfaces of the negative electrode current collector 131.

[0098] Optionally, the negative electrode current collector 131 may be, but is not limited to, a copper sheet.

[0099] Optionally, the negative electrode active layer 132 includes a negative electrode active material, a second conductive agent, a second binder, and a second thickener.

[0100] Alternatively, the negative electrode active material may be, but is not limited to, graphite.

[0101] Please see again Figures 1 to 5, the embodiment of the present application also provides a battery 100, the battery 100 includes an electrode assembly 10, an electrolyte and a shell assembly 20. The electrode assembly 10 includes a positive electrode plate 11, a separator 12 and a negative electrode plate 13; the electrolyte includes an electrolyte salt, the electrolyte salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the mass ratio of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is G; the shell assembly 20 includes a first end cap assembly 21, a shell 22 and a second end cap assembly 23, the shell 22 is a hollow structure, the first end cap assembly 21 and the second end cap assembly 23 are respectively arranged at opposite ends of the shell 22, the first end cap assembly 21, the shell 22 and the second end cap assembly 23 enclose a receiving cavity 24, the receiving cavity 24 is used to receive the electrode assembly 10 and the electrolyte; the first end cap assembly 21 includes a first top The battery 100 includes a cover 211 and a first explosion-proof valve 212, wherein the first top cover 211 is arranged around the outer periphery of the first explosion-proof valve 212, and the first top cover 211 is electrically connected to the positive electrode plate 11; the second end cover assembly 23 includes a second top cover 231, a negative electrode column 232 and a second explosion-proof valve 233, wherein the second top cover 231 is arranged around the outer periphery of the second explosion-proof valve 233, the negative electrode column 232 is passed through the second top cover 231 and protrudes from the side of the second top cover 231 away from the housing 22, and the negative electrode column 232 is electrically connected to the negative electrode plate 13; the area ratio of the first explosion-proof valve 212 to the second explosion-proof valve 233 is B; wherein the battery 100 satisfies the relationship: 0.03≤G / B≤9.87.

[0102] The battery 100 of the embodiment of the present application may be, but is not limited to, at least one of a lithium-ion battery 100 , a sodium-ion battery 100 , and the like.

[0103] For detailed descriptions of other aspects of the housing assembly 20 , the electrode assembly 10 , the positive electrode sheet 11 , the separator 12 , the negative electrode sheet 13 , etc., please refer to the descriptions of the corresponding parts of the above embodiments, which will not be repeated here.

[0104] Specifically, the ratio G of the mass ratio of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate to the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 may be, but is not limited to, 0.03, 0.05, 0.1, 0.2, 0.3, 0.5, 0.8, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 9.87, etc.

[0105] In this embodiment, if G / B is too small, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is too small, and the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is too large. If G is too small, the thermal stability of the electrolyte is reduced, and the heat generated by the decomposition of lithium hexafluorophosphate increases when the battery 100 is overcharged. The decomposition heat and gas production cause the air pressure inside the battery 100 to increase sharply. If the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is too large at this time, that is, the difference in pressure relief capacity between the first explosion-proof valve 212 and the second explosion-proof valve 233 is too large, then the pressure relief rate of the second explosion-proof valve 233 with a smaller area is too low, thereby reducing the safety performance of the battery 100. The negative electrode column 232 of the battery 100 protrudes from the side of the second top cover 231 away from the shell 22. Therefore, during assembly and use, the second end cover assembly 23 with the negative electrode column 232 is usually facing upward and the first end cover assembly 21 is facing downward; as G increases, the dissociation degree of the electrolyte salt (i.e., lithium salt) can be improved, thereby improving the dynamic performance of the battery 100. However, when G / B is too large, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is too large, and the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is too small. When G is too large, the content of lithium bis(fluorosulfonyl)imide in the electrolyte is too high, which increases the total gas production when the battery 100 is overcharged, and the heavier gas in the gas production gathers on the side of the first explosion-proof valve 212, causing the first explosion-proof valve 212 to bear greater pressure. If B is too small at this time, the area of ​​the first explosion-proof valve 212 is too small, which reduces the pressure relief rate of the first explosion-proof valve 212 and increases the risk of overcharging the battery 100. In summary, when the ratio G of the mass ratio G of lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate and the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is in the range of 0.03≤G / B≤9.87, the first explosion-proof valve 212 and the second explosion-proof valve 233 can have a suitable pressure relief speed when the battery 100 is overcharged, thereby improving the safety performance of the battery 100, and at the same time, the battery 100 can have higher dynamic performance and cycle performance.

[0106] In some embodiments, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is in the range of 0.1≤G≤14.8.

[0107] Specifically, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate may be, but is not limited to, 0.1, 0.3, 0.5, 1, 2, 3, 5, 6, 8, 10, 11, 12, 13, 14, or 14.8.

[0108] When the battery 100 is overcharged, the electrolyte is rapidly consumed and vaporized, allowing the gas generated in the battery 100 to escape from the first explosion-proof valve 212 and the second explosion-proof valve 233. In this embodiment, compared to using only lithium hexafluorophosphate as the electrolyte salt, the combination of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate can increase the degree of dissociation of the electrolyte salt (i.e., lithium salt) and improve the kinetic performance of the battery 100. When the mass ratio G of lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is too small, the proportion of lithium hexafluorophosphate in the electrolyte salt is high, which reduces the thermal stability of the electrolyte, increases the risk of heat generation from the decomposition of lithium hexafluorophosphate, and reduces the safety performance of the battery 100. When the mass ratio G of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is too high, the content of lithium bis(fluorosulfonyl)imide in the electrolyte is too high, causing an increase in the total amount of gas produced when the battery 100 is overcharged, increasing the risk of overcharging. Furthermore, due to high temperature corrosion of the aluminum foil (i.e., the positive current collector 111 of the positive electrode sheet 11), the adhesion between the positive current collector 111 of the positive electrode sheet 11 and the positive active layer 112 is reduced, potentially leading to a risk of detachment, significantly reducing the cycle life of the battery 100. When the mass ratio G of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is within the range of 0.1≤G≤14.8, the battery 100 can have higher dynamic performance and cycle performance.

[0109] In some embodiments, the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is in the range of 1.5≤B≤3.

[0110] Specifically, the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 can be, but is not limited to, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.1, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, etc.

[0111] For the cylindrical battery 100, the surface of its first end cover assembly 21 (i.e., the end cover electrically connected to the positive electrode plate 11) facing away from the shell 22 is flat, and the second end cover assembly 23 (i.e., the end cover electrically connected to the negative electrode plate 13) is provided with a negative electrode column 232 on the side facing away from the shell 22. Therefore, when in use, the first end cover assembly 21 of the battery 100 is facing downward, and the second end cover assembly 23 of the battery 100 is set upward. When the battery 100 is overcharged, most of the electrolyte in the outer shell assembly 20 is consumed. Among the gases generated in the battery 100, the heavier gases will sink and gather at the position of the first end cover assembly 21 (i.e., the first explosion-proof valve 212), and the lighter gases will float up and gather at the position of the second end cover assembly 23 (i.e., the second explosion-proof valve 233), so that the gas pressure exerted on the second explosion-proof valve 233 is greater than the gas pressure exerted on the first explosion-proof valve 212. In this embodiment, by making the area of ​​the first explosion-proof valve 212 larger than the area of ​​the second explosion-proof valve 233, the first explosion-proof valve 212 has a better pressure relief capability than the second explosion-proof valve 233. This allows the first explosion-proof valve 212 to release gas pressure more quickly than the second explosion-proof valve 233 when the battery 100 is overcharged and the first and second explosion-proof valves 212, 233 explode, thereby improving the safety of the battery 100 during overcharge. However, if the area ratio B between the first explosion-proof valve 212 and the second explosion-proof valve 233 is too small, the second explosion-proof valve 233 becomes too large, increasing the design difficulties of the second top cover 231 and the negative electrode column 232. If the area of ​​the first explosion-proof valve 212 is too small (the positive electrode side explosion-proof valve), the first explosion-proof valve 212 cannot release pressure in a timely manner when the battery 100 is overcharged. Furthermore, this makes it difficult to adapt to application scenarios where the mass ratio G of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is low and gas production is high. In addition, when the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is too large, the first explosion-proof valve 212 is too large, and the space reserved for the first top cover 211 is too small, so that the first explosion-proof valve 212 and the first top cover 211 do not meet the design requirements. In addition, the pressure resistance of the first explosion-proof valve 212 is reduced, which may cause the first explosion-proof valve 212 to explode prematurely, affecting the normal use of the battery 100; the second explosion-proof valve 233 is too small, and the pressure release rate of the second explosion-proof valve 233 is slow when it explodes. The speed of gas release at the first explosion-proof valve 212 of the battery 100 is too slow, and the pressure cannot be released in time, which increases the risk of explosion of the battery 100, and it is difficult to match the application scenario with a large gas production when the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is low.When the area ratio B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is in the range of 1.5≤B≤3, when the first explosion-proof valve 212 and the second explosion-proof valve 233 explode, the gas is released faster from the first explosion-proof valve 212 of the battery 100, and the pressure resistance of the first explosion-proof valve 212 and the second explosion-proof valve 233 do not differ too much, so that the battery 100 will not explode prematurely and affect normal use.

[0112] In some embodiments, the area b1 of the first explosion-proof valve 212 is within a range of 120 mm. 2 ≤b1≤240mm 2 The second explosion-proof valve 233 has an area b2 of 90mm 2 ≤b2≤160mm 2 .

[0113] Specifically, the area b1 of the first explosion-proof valve 212 may be, but is not limited to, 120 mm. 2 , 140mm 2 , 150mm 2 , 160mm 2 , 180mm 2 , 200mm 2 , 220mm 2 , 240mm 2 If the area b1 of the first explosion-proof valve 212 is too small, the pressure relief capacity of the first explosion-proof valve 212 is reduced, and the safety performance of the battery 100 during overcharge is reduced; if the area b1 of the first explosion-proof valve 212 is too large, the area of ​​the first top cover 211 needs to be increased, which makes the battery 100 thicker and the number of turns of the electrode assembly 10 more. During the charge and discharge cycle, the part of the area near the inner side of the wound electrode assembly 10 is subjected to excessive extrusion stress during the lithium insertion and expansion process. The electrolyte in this part of the electrode assembly 10 is easily squeezed out, causing the part of the electrode assembly 10 near the winding center to be in a liquid-deficient state, which increases the gas production of the battery 100, thereby reducing the safety performance of the battery 100, and making lithium deposition more likely to occur, worsening the cycle performance of the battery 100.

[0114] Specifically, the area b2 of the second explosion-proof valve 233 may be, but is not limited to, 90 mm. 2 , 100mm 2 , 110mm 2 , 120mm 2 , 140mm 2 , 150mm 2 , 160mm 2If the area b1 of the second explosion-proof valve 233 is too small, the pressure relief capacity of the second explosion-proof valve 233 is reduced, and the safety performance of the battery 100 during overcharge is reduced; if the area b1 of the second explosion-proof valve 233 is too large, the area of ​​the second top cover 231 needs to be increased, which makes the battery 100 thicker and the number of turns of the electrode assembly 10 is increased. During the charge and discharge cycle, the part of the area near the inner side of the wound electrode assembly 10 is subjected to excessive extrusion stress during the lithium insertion and expansion process. The electrolyte in this part of the electrode assembly 10 is easily squeezed out, causing the part of the electrode assembly 10 near the winding center to be in a liquid-deficient state, resulting in an increase in the gas production of the battery 100, thereby reducing the safety performance of the battery 100 and making lithium deposition more likely to occur, worsening the cycle performance of the battery 100; in addition, the design difficulty of the negative electrode 232 and the second explosion-proof valve 233 is increased.

[0115] Please see again Figure 2 In some embodiments, the shell assembly 20 is cylindrical, the central axis of the shell assembly 20 extends along the arrangement direction of the first end cover assembly 21, the shell 22 and the second end cover assembly 23, and the length L of the shell assembly 20 and the diameter D of the shell assembly 20 satisfy the relationship: 2.43≤L / D≤5.98.

[0116] It can be understood that the outer shell assembly 20 is cylindrical, the shell 22 is a cylindrical structure, and the first end cover assembly 21 and the second end cover assembly 23 are circular structures.

[0117] Specifically, the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 may be, but is not limited to, 2.43, 2.6, 2.8, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 5.98, etc.

[0118] In this embodiment, the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 is too small, so the electrode assembly 10 of the battery 100 is wound a large number of times and the electrode assembly 10 is thicker. During the charge and discharge cycle, a part of the area near the inner side of the wound electrode assembly 10 is subjected to excessive extrusion stress during the lithium insertion and expansion process. The electrolyte in this part of the electrode assembly 10 is easily squeezed out, causing the part of the electrode assembly 10 near the winding center to be in a liquid-deficient state, which increases the gas production of the battery 100, thereby reducing the safety performance of the battery 100, and making lithium plating more likely to occur, worsening the cycle performance of the battery 100. The cylindrical battery 100 is usually injected from one end of the cylinder. After injection, it first enters the gap between the shell component 20 and the wound electrode component 10, and then gradually infiltrates the entire electrode component 10 from the outer ring of the electrode component 10 and the two ends of the electrode component 10 (the end close to the first end cover component 21 and the end close to the second end cover component 23). When the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 is too large, the design of the electrode component 10 is too long, and the path of the electrolyte from the two ends of the electrode component 10 to the middle is too long, so that the electrolyte flow along the battery 100 is too long. Insufficient or insufficient wetting of the electrode assembly 10 near the middle of the length of the battery 100 can easily form an unwetted zone in the middle of the length of the battery 100, making lithium deposition more likely in this zone, reducing the cycle performance of the battery 100 and causing the battery 100 to prematurely stop cycling. Furthermore, this increases the likelihood of side reactions between the unwetted zone and the solvent in the electrolyte, which in turn increases gas production. The exhaust path is longer, and the pressure within the battery 100 is released too slowly, preventing it from being discharged in a timely manner. This increases the internal pressure of the battery 100 and increases the risk of explosion. When the ratio L / D of the length L of the battery 100 to the diameter D of the battery 100 is in the range of 2.43 ≤ L / D ≤ ​​5.98, the entire electrolyte can have good wettability with the electrode assembly 10, making it less prone to gas production. This results in the battery 100 having better safety performance and better cycle performance.

[0119] Optionally, the electrolyte further includes an organic solvent, and the organic solvent includes cyclic carbonate and chain carbonate.

[0120] For descriptions of other aspects of the electrolyte, organic solvent, etc., please refer to the descriptions of the corresponding parts of the above embodiments, which will not be repeated here.

[0121] The battery 100 of the present application is further described below through specific embodiments.

[0122] Examples 1 to 32, Comparative Examples 1 to 6

[0123] The battery 100 of each embodiment and comparative example was prepared by the following steps:

[0124] (1) Preparation of electrolyte: In an argon atmosphere glove box with a moisture content of ≤1ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were prepared and mixed in a preset ratio. After sealing and isolating from water, the mixture was placed in a 0°C freezer and stabilized for 2 hours. The mixture was taken out and quickly transferred to a glove box. Lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide were added and stirred until completely dissolved. After the temperature stabilized, film-forming additives fluoroethylene carbonate (FEC, 1.5wt%), vinyl sulfate (DTD), and vinylene carbonate (VC, 3wt%) were added and mixed evenly to obtain the electrolyte.

[0125] The ratio of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in the electrolyte of each embodiment and comparative example is shown in Table 1 below.

[0126] The mass ratios of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate in the electrolytes of the embodiments and comparative examples are shown in Table 1 below, wherein the total molar concentration of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate in the electrolyte is 1 mol / L.

[0127] (2) Preparation of the positive electrode sheet 11: The positive electrode active material lithium iron phosphate (LiFePO4), conductive carbon black (Super-P), and binder (polyvinylidene fluoride, PVDF) were mixed in a mass ratio of 94:3:3; N-methylpyrrolidone (NMP) was then added as a solvent to prepare a positive electrode slurry with a solid content of 60 wt%, and the mixture was stirred evenly. The positive electrode slurry was then evenly coated on one surface of a 10 μm thick aluminum foil (positive electrode current collector 111). After drying, cold pressing, slitting, and die-cutting, the positive electrode sheet 11 to be wound was obtained. The thickness of the single surface of the positive electrode active layer 112 was 100 μm.

[0128] (3) Preparation of the negative electrode sheet 13: The negative electrode active material artificial graphite, the thickener sodium carboxymethyl cellulose (CMC), the conductive carbon black (Super-P), and the binder styrene-butadiene rubber latex (SBR) were mixed in a mass ratio of 96:2:1:1, and deionized water was added to prepare a negative electrode slurry with a solid content of 50 wt%, and stirred evenly. The negative electrode slurry was evenly coated on one surface of a copper foil (negative electrode current collector 131) with a thickness of 6 μm. After drying, cold pressing, slitting, and die-cutting, the negative electrode sheet to be wound was obtained. The thickness of the single surface of the negative electrode active layer 132 was 70 μm.

[0129] (4) Preparation of the diaphragm 12: A 16 μm polyethylene film (PE) was used as the diaphragm 12.

[0130] (5) Assembly of battery 100: stack the positive electrode sheet 11, separator 12, and negative electrode sheet 13 in order, so that the separator 12 is located between the positive electrode sheet 11 and the negative electrode sheet 13 to play an isolating role, and then wind them into a cylindrical electrode assembly 10; after welding the tabs, place the electrode assembly 10 with the tabs in the shell assembly 20, inject the above-mentioned electrolyte after drying, and then stand at room temperature, form, inject, age, weld, helium test, capacity, OCV test and other processes to finally prepare the battery 100, wherein the area of ​​the second explosion-proof valve 233 of the shell assembly 20 is 110mm 2 The area ratios of the first explosion-proof valve 212 and the second explosion-proof valve 233 of the housing assembly 20 are shown in Table 1 below.

[0131] Various performance tests were performed on the above embodiments and comparative examples.

[0132] (1) Method for determining the low-temperature freezing point of the electrolyte: 30 g of the electrolyte of each embodiment and comparative example was placed in a 50 ml transparent glass bottle. The temperature was placed in a high-low temperature cabinet with a test range of -60°C to 100°C. The temperature was gradually lowered from -10°C in a 2°C gradient. Each time the temperature was lowered, it was stabilized for 1 hour and the phenomenon was recorded until the electrolyte solidified. The freezing point of the electrolyte (i.e., the freezing temperature of the electrolyte) was recorded.

[0133] (2) Charge and discharge cycle test: The battery 100 of each embodiment and comparative example was subjected to a constant current charge and discharge cycle test on a charge and discharge instrument. The test temperature was 25° C., the charge and discharge rate was 1C, and the charge and discharge voltage window was 2.5 V to 3.65 V. The capacity retention rate after 300 cycles was calculated.

[0134] The calculation formula is: Capacity retention after the nth cycle = (Discharge capacity after the nth cycle / Discharge capacity at the first cycle) × 100%. A complete charge and discharge cycle is generally referred to as one charge and discharge cycle. That is, the battery 100 is first charged from 2.5V to 3.65V, and then discharged from 3.65V to 2.5V, thus forming one charge and discharge cycle. Cycle N means repeating this process N times.

[0135] (3) Thermal runaway test: 1) Charge the battery 100 to be tested to 100% state of charge (SOC), and place the initialized battery 100 in a thermal runaway test device; 2) Select a heating component and a temperature sensor, and set them on the surface of the battery 100 to be tested, set the temperature sampling period to 1S, and continuously monitor three temperature rise rate values ​​greater than 3℃ / s, or fire, or explosion as the judgment conditions for thermal runaway; 3) Connect the tested battery 100 to the charging and discharging device and its voltage data sampling line; 4) Charge at a constant current of I=P / U, start heating, and record the status and rupture mode of the first explosion-proof valve 212 and the second explosion-proof valve 233; 5) When the judgment conditions for thermal runaway are triggered or the temperature reaches 300℃ or the test time reaches 4h, stop charging and heating, observe for 1h, and record the status and rupture mode of the first explosion-proof valve 212 and the second explosion-proof valve 233.

[0136] The performance test results of each embodiment and comparative example are shown in Table 2 below.

[0137] Table 1 Parameter design of the battery 100 of each embodiment and comparative example

[0138] Table 2 Performance parameters of the battery 100 of each embodiment and comparative example

[0139]

[0140] It can be seen from the test results of Examples 1 to 5 in Table 1 that, when other conditions remain unchanged, when the mass ratio A of cyclic carbonate to chain carbonate is low and B / A is too high, the battery 100 has a low low-temperature freezing point, but its 300-cycle cycle capacity retention rate is low; as the mass ratio A of cyclic carbonate to chain carbonate increases, the low-temperature freezing point of the electrolyte gradually increases, and the battery 100 has a high cycle capacity retention rate after 300 cycles at room temperature (Examples 2 to 4 are all greater than or equal to 88.1%). The cycle capacity retention of the battery 100 first gradually increases and then gradually decreases. During the thermal runaway test, at least one of the first explosion-proof valve 212 and the second explosion-proof valve 233 of the battery 100 can explode, thereby relieving the pressure on the battery 100 and preventing the battery 100 from exploding. When the mass ratio A of the cyclic carbonate to the linear carbonate is too high (as in Example 5), the low-temperature freezing point of the battery 100 increases significantly, the capacity retention rate after 300 cycles decreases significantly, and when the battery 100 experiences thermal runaway, valve explosions occur on both sides. This indicates that when the battery 100 is overcharged, more gas is generated and the gas pressure inside the battery 100 is relatively high.

[0141] The test results of Examples 3, 6, and 9 show that, with other conditions remaining unchanged, a ratio of the first explosion-proof valve 212 to the second explosion-proof valve 233 that is too large or too small cannot meet the design requirements of the battery 100. When the area ratio B of the first explosion-proof valve 212 to the second explosion-proof valve 233 is between 1.5 and 3, at least one of the first explosion-proof valve 212 and the second explosion-proof valve 233 can explode during the overcharge thermal runaway test of the battery 100, thereby relieving the pressure in the battery 100 and preventing explosion.

[0142] The test results of Examples 3, 18, and 22 show that, with other conditions remaining unchanged, when the aspect ratio of the battery 100 is 2.43 ≤ L / D ≤ ​​5.98, at least one of the first explosion-proof valve 212 and the second explosion-proof valve 233 can explode during the thermal runaway test, thereby relieving the pressure in the battery 100 and preventing the battery 100 from exploding. When the aspect ratio of the battery 100 is too large, the battery 100 is prone to explosion when overcharged. When the aspect ratio of the battery 100 is 2.43 ≤ L / D ≤ ​​5.98, as the aspect ratio increases, the room temperature cycle capacity of the battery 100 after 300 cycles first gradually increases and then gradually decreases, but is always greater than or equal to 88.23%.

[0143] The test results of Examples 3, 23, and 24 show that when the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate is 0.5 ≤ A1 ≤ 2, as the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate in the electrolyte increases, the low-temperature freezing point of the electrolyte decreases, and the cycle capacity retention rate of battery 100 slightly increases. When the mass ratio A1 of ethyl methyl carbonate to dimethyl carbonate is 0.5 ≤ A1 ≤ 2, the low-temperature freezing point of the electrolyte can cover a range of -30°C to -64°C.

[0144] From the test results of Examples 3, 10 to 17, 23, and 25 to 32, it can be seen that, when other conditions remain unchanged, when the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is small (such as in Example 10), the electrolyte has a lower low-temperature freezing point, but the capacity retention rate of the battery 100 after 300 cycles at room temperature is low; as the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate increases (such as in Examples 11 to 16), the low-temperature freezing point of the electrolyte gradually increases. The capacity of the battery 100 after 300 cycles at room temperature first increases gradually and then decreases gradually. When the battery 100 is in thermal runaway, at least one of the first explosion-proof valve 212 and the second explosion-proof valve 233 of the battery 100 can burst, thereby relieving the pressure of the battery 100 and preventing the battery 100 from exploding. When the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is too large (such as in Example 17), the low-temperature freezing point of the electrolyte is too high. During the thermal runaway test, the entire battery 100 explodes, and the safety performance deteriorates.

[0145] The test results of Examples 10 to 17 show that when the mass ratio of the ethyl methyl carbonate to the dimethyl carbonate in the electrolyte is relatively high, the battery 100 has a lower low-temperature freezing point. At this time, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate in the electrolyte also has a significant impact on the low-temperature freezing point of the electrolyte. As the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate increases, the low-temperature freezing point of the electrolyte increases rapidly.

[0146] From the test results of Examples 23 and 25 to 32, it can be seen that when the mass ratio of the ethyl methyl carbonate to the dimethyl carbonate in the electrolyte is relatively low, the battery 100 has a higher low-temperature freezing point. At this time, the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate in the electrolyte has a relatively small effect on the low-temperature freezing point of the electrolyte. As the mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate increases, the low-temperature freezing point of the electrolyte gradually increases, but the increase is relatively slow.

[0147] From the test results of Examples 1 to 9 and Comparative Examples 1 to 4, it can be seen that when 0.17≤A≤0.67, 1.5≤B≤3, and 2.23≤B / A≤17.65 are satisfied at the same time, the battery 100 has a high cycle capacity retention rate (the capacity retention rate after 300 cycles is ≥87.32%, and the highest is 94.21%), and has high safety performance. When overcharged, at least one of the first explosion-proof valve 212 and the second explosion-proof valve 233 can explode to relieve the pressure on the battery 100 and avoid the risk of explosion of the battery 100.

[0148] From the test results of Comparative Example 1, it can be seen that when B>3, B / A>17.65, and L / D>5.98 of the first explosion-proof valve 212 and the second explosion-proof valve 233, the entire battery 100 explodes during the thermal runaway test.

[0149] From the test results of Comparative Example 2, it can be seen that when B of the first explosion-proof valve 212 and the second explosion-proof valve 233 is less than 1.5 and B / A is less than 2.43, the design requirements of the battery 100 are not met.

[0150] From the test results of Comparative Example 3, it can be seen that when A<0.17, B>3, and B / A>17.65, the electrolyte has a lower low-temperature freezing point, but the battery 100 does not meet the design requirements.

[0151] From the test results of Comparative Example 4, it can be seen that when A>0.67, B<1.5, and B / A<2.23, the low-temperature freezing point of the electrolyte is high, and the capacity retention rate of the battery 100 after 300 cycles is greatly reduced.

[0152] From the test results of Comparative Example 5, it can be seen that when B>3, G<0.1, B / A>17.65, and G / B<0.03, the electrolyte has a lower low-temperature freezing point, but the battery 100 does not meet the design requirements.

[0153] From the test results of Comparative Example 6, it can be seen that when B is less than 1.5, G is greater than 14.8, and G / B is greater than 13.33, the low-temperature freezing point of the electrolyte increases, but is still relatively low. The capacity retention rate of the battery 100 after 300 cycles is also relatively high. When the battery 100 is subjected to a thermal runaway test, double-sided valve explosion occurs, indicating that when the battery 100 is overcharged, more gas is produced and the gas pressure inside the battery 100 is relatively high.

[0154] See Figure 8 The embodiment of the present application further provides an energy storage device 200 , which includes a box 210 and a plurality of batteries 100 described in the embodiment of the present application. The plurality of batteries 100 are stacked and accommodated in the box 210 .

[0155] The term "plurality" means greater than or equal to two.

[0156] It can be understood that the multiple batteries 100 of the energy storage device 200 can be connected in parallel with each other; or in series with each other; or partially in parallel and partially in series (in other words, mixed connection). This application does not specifically limit the connection method of the multiple batteries 100 of the same energy storage device 200.

[0157] Optionally, the energy storage device may be at least one of a small energy storage box, a large energy storage cabinet, an energy storage module, etc. This application does not specifically limit the form of the energy storage device. The form of the energy storage device of this application is only one of its many forms and should not be understood as a limitation on the energy storage device of this application.

[0158] It is understood that the housing 210 has a receiving cavity, and multiple batteries 100 are received in the receiving cavity. In some embodiments, each receiving cavity receives one battery 100. In other embodiments, each receiving cavity receives multiple batteries 100.

[0159] See Figure 9 and Figure 10 , an embodiment of the present application also provides an energy storage system 300, which includes: an electric energy conversion device 310 and the energy storage device 200 described in the embodiment of the present application, the electric energy conversion device 310 is electrically connected to the energy storage device 200, the electric energy conversion device 310 is used to convert other forms of energy into electric energy, and the energy storage device 200 is used to store the electric energy.

[0160] Optionally, the electric energy conversion device 310 can convert at least one other form of energy such as solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electric energy.

[0161] Optionally, the number of the electric energy conversion devices 310 may be one or more. When there are multiple electric energy conversion devices 310, the multiple electric energy conversion devices 310 may be connected in series or in parallel, which is not specifically limited in this application.

[0162] Optionally, the electric energy conversion device 310 may be, but is not limited to, at least one of a photovoltaic panel, a wind power generation device, a hydropower generation device, and the like.

[0163] Optionally, the number of the energy storage devices 200 may be one or more. When the number of the energy storage devices 200 is multiple, the multiple energy storage devices 200 are connected in series or in parallel, which is not specifically limited in this application.

[0164] During operation, the power conversion device 310 converts other forms of energy into electrical energy and stores it in the energy storage device 200. This stored energy can be used to supply loads such as streetlights and household appliances during peak electricity prices, or to provide power during power outages. The electricity generated by the power conversion device 310 can also be supplied to the grid via high-voltage cables to alleviate pressure on the grid during peak hours.

[0165] Mentioning "embodiments" and "implementation methods" in this application means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is understood explicitly and implicitly by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should be understood that the features, structures or characteristics described in the various embodiments of this application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of this application, unless there is a contradiction between them.

[0166] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred implementation modes, ordinary technicians in this field should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A battery, characterized in that: include: An electrode assembly, comprising a positive electrode sheet, a separator, and a negative electrode sheet; An electrolyte, wherein the electrolyte comprises an electrolyte salt, wherein the electrolyte salt comprises lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the mass ratio of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is G; as well as A shell assembly, the shell assembly comprising a first end cap assembly, a shell and a second end cap assembly, the shell being a hollow structure, the first end cap assembly and the second end cap assembly being respectively disposed at opposite ends of the shell, the first end cap assembly, the shell and the second end cap assembly enclosing a receiving chamber, the receiving chamber being used to receive the electrode assembly and the electrolyte; the first end cap assembly comprising a first top cap and a first explosion-proof valve, the first top cap being disposed around the periphery of the first explosion-proof valve, the first top cap being electrically connected to the positive electrode sheet; the second end cap assembly comprising a second top cap, a negative electrode column and a second explosion-proof valve, the second top cap being disposed around the periphery of the second explosion-proof valve, the negative electrode column being disposed through the second top cap and protruding from a side of the second top cap facing away from the shell, the negative electrode column being electrically connected to the negative electrode sheet; the area ratio of the first explosion-proof valve to the second explosion-proof valve being B; The battery satisfies the relationship: 0.03≤G / B≤9.87; and the range of the area ratio B between the first explosion-proof valve and the second explosion-proof valve is: 1.5≤B≤3.

2. The battery according to claim 1, characterized in that The mass ratio G of the lithium bis(fluorosulfonyl)imide to the lithium hexafluorophosphate is in the range of 0.1≤G≤14.

8.

3. The battery according to claim 1, characterized in that The area of ​​the first explosion-proof valve is b1, which is 120 mm. 2 ≤b1≤240mm 2 The second explosion-proof valve area b2 range is 90mm 2 ≤b2≤160mm 2 .

4. The battery according to any one of claims 1 to 3, characterized in that The shell assembly is cylindrical, and the central axis of the shell assembly extends along the arrangement direction of the first end cover assembly, the shell and the second end cover assembly. The length L of the shell assembly and the diameter D of the shell assembly satisfy the relationship: 2.43≤L / D≤5.

98.

5. The battery according to claim 1, characterized in that The electrolyte comprises an electrolyte salt and an organic solvent, the organic solvent comprises a cyclic carbonate and a chain carbonate, and the mass ratio of the cyclic carbonate to the chain carbonate is A; The battery satisfies the relationship: 2.23≤B / A≤17.

65.

6. The battery according to claim 5, characterized in that The mass ratio A of the cyclic carbonate to the linear carbonate is in the range of 0.17≤A≤0.

67.

7. The battery according to any one of claims 1 to 3, 5 and 6, characterized in that: The electrolyte further includes a sulfur-containing additive, which includes at least one of bis(vinylsulfone)methane, methylene methanedisulfonate, ethylene sulfate, propylene sultone, butyl sultone, and propylene sulfite; the mass fraction of the sulfur-containing additive in the electrolyte is 0.1wt%≤w1≤1wt%.

8. An energy storage device, characterized in that: include: Box; as well as A plurality of batteries according to any one of claims 1 to 7, wherein the plurality of batteries are housed in the box.

9. An energy storage system, characterized in that: include: An electric energy conversion device and an energy storage device as described in claim 8, wherein the electric energy conversion device is electrically connected to the energy storage device, the electric energy conversion device is used to convert other forms of energy into electric energy, and the energy storage device is used to store the electric energy.

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