Cylindrical battery, energy storage device and energy storage system

Abstract

The invention provides a cylindrical battery, an energy storage device and an energy storage system. The cylindrical battery provided by the embodiment of the invention comprises an electrolyte, the electrolyte comprises an electrolyte salt and an organic solvent, and the mass fraction of the electrolyte salt in the electrolyte is y wt%; the electrode assembly comprises an electrode plate, the electrode plate comprises a current collector and a plurality of tabs, the current collector and the tabs are electrically connected, the tabs are arranged on the same side of the current collector at intervals, and the distance between every two adjacent tabs is d; the electrode assembly is of a winding structure, the electrode assembly is provided with a center hole, the diameter of the center hole of the electrode assembly is L, the unit of d is mm, and the unit of L is mm; the battery also meets the relational expression: d = 10k1. Y-L, and the range of k1 is 3.7 mm < = k1 < = 17.14 mm. The cylindrical battery provided by the invention has relatively long cycle life.

Description

Technical Field

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

[0002] The cylindrical battery itself has the characteristics of good single consistency, high temperature resistance, safety and not easy to explode, high energy density, and small internal resistance, making it occupy a certain proportion in actual working conditions. However, the electrolyte of the cylindrical battery in the related art has poor progressivity, thus affecting the electrical performance of the cylindrical battery, resulting in a low cycle capacity retention rate and a low cycle life of the cylindrical battery. Summary of the Invention

[0003] An embodiment of the present application provides a cylindrical battery with a high cycle life.

[0004] In a first aspect, an embodiment of the present application provides a cylindrical battery, which includes:

[0005] An electrolyte, which includes an electrolyte salt and an organic solvent, and the mass fraction of the electrolyte salt in the electrolyte is y wt%; and

[0006] An electrode assembly, which includes electrode tabs, and the electrode tabs include a current collector and a plurality of tabs electrically connected thereto. The plurality of tabs are spaced apart on the same side of the current collector, and the distance between adjacent tabs is d; the electrode assembly has a wound structure and has a central hole, and the diameter of the central hole of the electrode assembly is L, where the unit of d is mm and the unit of L is mm;

[0007] The battery also satisfies the relationship: d = 10k 1 ·y - L, where k 1 ranges from 3.7 mm ≤ k 1 ≤ 17.14 mm.

[0008] In some embodiments, the organic solvent includes a cyclic carbonate and a linear carbonate, and the mass ratio of the cyclic carbonate to the linear carbonate in the electrolyte is A;

[0009] The battery satisfies the relationship: L·d = 10k 2 ·A, where k 2 ranges from 0.6 mm 2 ≤ k 2 ≤ 23.53 mm 2 .

[0010] In some embodiments, the range of the mass fraction y wt% of the electrolyte salt in the electrolyte is: 8.75 wt% ≤ y wt% ≤ 16.2 wt%.

[0011] In some embodiments, the distance d between two adjacent tabs ranges from 1 mm ≤ d ≤ 5 mm.

[0012] In some embodiments, the diameter L of the central hole of the electrode assembly ranges from 5 mm ≤ L ≤ 10 mm.

[0013] In some embodiments, the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte ranges from 0.17 ≤ A ≤ 0.67.

[0014] In some embodiments, the number of turns of the wound electrode assembly is M turns, where M turns include N steps, each step includes multiple turns, each turn of the electrode tab includes multiple tabs, the sizes of the multiple tabs of each step are the same, in the direction from the outermost circle to the innermost circle of the electrode assembly, the widths of the tabs of different steps gradually decrease in gradient and the heights of the tabs of different steps also gradually decrease in gradient, where M > N.

[0015] In some embodiments, the number N of steps of the electrode assembly ranges from 2 ≤ N ≤ 10.

[0016] In some embodiments, the number n of tabs of the electrode tab ranges from 400 ≤ n ≤ 2000.

[0017] In some embodiments, the height h1 of the tab of the step of the electrode assembly closest to the central hole ranges from 2 mm ≤ h1 ≤ 6 mm.

[0018] In some embodiments, when the electrode assembly is in a wound structure, the radial width w1 of the step farthest from the central hole ranges from 100 mm ≤ w1 ≤ 300 mm.

[0019] In some embodiments, the electrode tab includes a tabless region, the tabless region is disposed close to the central hole and is connected to the step closest to the central hole, when the electrode assembly is flattened, the length s1 of the tabless region ranges from 100 mm ≤ s1 ≤ 500 mm.

[0020] In some embodiments, the length s2 of the electrode tab corresponding to the innermost step of the electrode assembly when flattened ranges from 300 mm ≤ s2 ≤ 500 mm.

[0021] In a second aspect, an embodiment of the present application further provides an energy storage device, which includes:

[0022] A box body; and

[0023] A plurality of cylindrical batteries according to the embodiments of the present application, and the plurality of cylindrical batteries are housed in the box body.

[0024] In a third aspect, an embodiment of the present application further provides an energy storage system, which includes:

[0025] The energy storage device described in the embodiment of the present application; and

[0026] An electric energy conversion device, 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.

[0027] The cylindrical battery of the embodiment of the present application satisfies the relationship L·d = 10k 2 ·A. By designing the values of the relationship L·d = 10k 2 ·A and k 2 , the cylindrical battery has better electrolyte wettability, so that the specific capacity of the cylindrical battery can be better exerted, the cylindrical battery has a higher room temperature cycle capacity retention rate, and thus has a higher room temperature cycle service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 is a schematic structural diagram of a cylindrical battery according to an embodiment of the present application.

[0030] Figure 2 is a schematic cross-sectional structural diagram of the cylindrical battery according to an embodiment of the present application along the Figure 1 A-A direction in

[0031] Figure 3 is a schematic structural diagram of an electrode tab when unfolded according to an embodiment of the present application.

[0032] Figure 4 is a schematic top view structural diagram of an electrode assembly when wound according to an embodiment of the present application.

[0033] Figure 5 is a schematic cross-sectional structural diagram of a positive electrode tab according to an embodiment of the present application.

[0034] Figure 6 is a schematic cross-sectional structural diagram of a negative electrode tab according to an embodiment of the present application.

[0035] Figure 7 is a schematic structural diagram of an energy storage device according to an embodiment of the present application.

[0036] Figure 8 It is a structural block diagram of an energy storage system according to an embodiment of the present application.

[0037] Figure 9 It is an application scenario diagram of an energy storage system according to an embodiment of the present application.

[0038] Explanation of reference numerals:

[0039] 100 - cylindrical battery, 10 - electrode assembly, 11 - electrode tab, 111 - current collector, 112 - tab, 11a - positive electrode tab, 111a - positive current collector, 112a - positive tab, 113a - positive active layer, 11b - negative electrode tab, 111b - negative current collector, 112b - negative tab, 113b - negative active layer, 12 - separator, 13 - central hole, 14 - tabless area, 15 - step, 20 - housing, 30 - end - cover assembly, 200 - energy storage device, 210 - box body, 300 - energy storage system, 310 - power conversion device. Detailed implementation manners

[0040] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0041] The terms "first", "second", etc. in the specification and claims of the present application and the above - mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non - exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0042] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0043] It should be noted that, for the sake of convenience of description, in the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted.

[0044] Currently, the generation of green electric energy generally relies on photovoltaics, wind power, water potential, etc. However, wind energy and solar energy generally have problems such as strong intermittency and large volatility, which can cause grid instability. There is not enough electricity during peak electricity consumption, and too much electricity during low electricity consumption. The unstable voltage can also damage the electricity. Therefore, the problem of "abandoning wind and light" may be caused due to insufficient electricity demand or insufficient grid acceptance capacity. To solve these problems, energy storage is required. That is, the electric energy is converted into other forms of energy through physical or chemical means and stored, and the energy is converted into electric energy and released when needed. Simply put, energy storage is similar to a large "portable power bank". When photovoltaics and wind energy are sufficient, the electric energy is stored, and the stored energy is released when needed.

[0045] The battery is the smallest energy storage unit of the energy storage device and the energy storage system. The performance of the battery directly affects the performance and application of the energy storage device and the energy storage system.

[0046] The cylindrical battery itself has the characteristics of good single consistency, high temperature resistance, safety and not easy to explode, high energy density, and small internal resistance, making it occupy a certain proportion in actual working conditions. However, the electrolyte of the cylindrical battery in the related technology has poor progressivity, which affects the electrical performance of the cylindrical battery, resulting in a low cycle capacity retention rate and a low cycle life of the cylindrical battery.

[0047] Please refer to Figures 1 to 3 , an embodiment of the present application provides a cylindrical battery 100, the cylindrical battery 100 includes an electrolyte and an electrode assembly 10. The electrolyte includes an electrolyte salt and an organic solvent, and the mass fraction of the electrolyte salt in the electrolyte is y wt%; the electrode assembly 10 includes an electrode tab 11, the electrode tab 11 includes a current collector 111 and a plurality of tabs 112 that are electrically connected, and the plurality of tabs 112 are spaced apart on the same side of the current collector 111, and the distance between adjacent two tabs 112 is d; the electrode assembly 10 is in a wound structure, the electrode assembly 10 has a central hole 13, and the diameter of the central hole 13 of the electrode assembly 10 is L, where the unit of d is mm and the unit of L is mm; the cylindrical battery 100 also satisfies the relational expression: d = 10k 1 ·y - L, where k 1 ranges from 3.7 mm ≤ k 1 ≤ 17.14 mm.

[0048] The cylindrical battery 100 of the embodiment of the present application can be applied to energy storage devices such as battery modules (also known as energy storage modules), small energy storage boxes, and large energy storage cabinets. The energy storage device is used to store electric energy and can supply electrical loads such as street lights and household appliances for use during peak electricity prices, or supply power when the power grid is powered off / out of power.

[0049] The term "plurality" means greater than or equal to two.

[0050] It should be noted that the electrode assembly 10 of the cylindrical battery 100 is wound using a winding pin. Since the winding pin has a certain diameter, there is a cylindrical central hole 13 in the center of the wound electrode assembly 10, and the diameter of the central hole 13 is related to the diameter of the winding pin.

[0051] It should be noted that the distance d between two adjacent tabs 112 in the embodiments of the present application refers to the minimum distance d between two adjacent tabs 112 along the length direction of the electrode assembly 10 or the electrode tab 11 when the electrode assembly 10 or the electrode tab 11 is flattened. It can also be understood that the distance between the roots of two adjacent tabs 112, in other words, the distance between the roots of two adjacent tabs 112 connecting the current collector 111.

[0052] It should be noted that the central hole 13 of the electrode assembly 10 refers to the hollow hole in the middle position after the electrode assembly 10 is wound.

[0053] Optionally, the electrode assembly 10 includes a positive electrode tab 11a, a separator 12, and a negative electrode tab 11b. The separator 12 is located between the positive electrode tab 11a and the negative electrode tab 11b and is used to separate the positive electrode tab 11a from the negative electrode tab 11b. It should be noted that at least a part of the electrode assembly 10 is immersed in the electrolyte.

[0054] Optionally, the electrode tab 11 can be a positive electrode tab 11a or a negative electrode tab 11b. When the electrode tab 11 is a positive electrode tab 11a, the current collector 111 is a positive current collector 111a, and the tab 112 is a positive tab 112a. When the electrode tab 11 is a negative electrode tab 11b, the current collector 111 is a negative current collector 111b, and the tab 112 is a negative tab 112b. Optionally, multiple positive tabs 112a of the cylindrical battery 100 are located on the same side of the cylindrical battery 100, and multiple negative tabs 112b are all located on the other side of the cylindrical battery 100.

[0055] Optionally, the tab 112 in the embodiments of the present application can be, but is not limited to, a die-cut tab.

[0056] Specifically, k 1 The value of can be, but is not limited to, 3.7mm, 4.0mm, 5.0mm, 6.0mm, 7.0mm, 8.0mm, 9.0mm, 10.0mm, 11.0mm, 12.0mm, 13.0mm, 14.0mm, 15.0mm, 16.0mm, 17.0mm, 17.14mm, etc.

[0057] In this embodiment, k 1When the value is too low, it is necessary to make the content of the electrolyte salt (such as lithium salt) in the electrolyte higher, the diameter L of the central hole 13 and the distance d between the roots of the adjacent tabs 112 smaller; if the content of the electrolyte salt in the electrolyte is too high, it will lead to an increase in the density of the electrolyte, an increase in viscosity, affect the wettability in the cylindrical battery 100 system, and at the same time increase the cost of the cylindrical battery 100; if the diameter L of the central hole 13 is too small and the distance d between the roots of the adjacent tabs 112 is too low, it will result in insufficient electrolyte injection and wetting channels and insufficient wetting.

[0058] In this embodiment, k 1 When the value is too high, it is necessary to make the content of the electrolyte salt (such as lithium salt) in the electrolyte lower, the diameter L of the central hole 13 and the distance d between the roots of the adjacent tabs 112 larger; if the content y of the electrolyte salt in the electrolyte is too low, the amount of migratable lithium ions decreases, the conductivity decreases, the polarization increases, the electrolyte consumption increases, resulting in insufficient later cycle life of the cylindrical battery 100; at the same time, a wider design of the diameter of the central hole 13 will squeeze the design area of the electrode tab 11, causing the design of the electrode tab 11 to tend to the high compaction direction, affecting the wetting of the electrode tab 11 and deteriorating the cycle performance; if the distance d between the roots of the adjacent tabs 112 is designed too large, although it is beneficial for liquid injection and wetting, the area for welding the tabs 112 will be smaller, prone to poor welding and risk of virtual soldering.

[0059] The cylindrical battery 100 of the embodiment of the present application satisfies the relational expression d = 10k 1 ·y - L. By designing the numerical values of the relational expression d = 10k 1 ·y - L and k 1 Thus, the cylindrical battery 100 has better electrolyte wettability, so that the specific capacity of the cylindrical battery 100 can be better exerted, the cylindrical battery 100 has a higher normal temperature cycle capacity retention rate, and thus has a higher normal temperature cycle service life.

[0060] In some embodiments, the organic solvent includes cyclic carbonates and chain carbonates, and the mass ratio of the cyclic carbonate to the chain carbonate in the electrolyte is A; the cylindrical battery 100 satisfies the relational expression: L·d = 10k 2 ·A, where k 2 ranges from 0.6 mm 2 ≤ k 2 ≤ 23.53 mm 2 .

[0061] Specifically, the numerical value of k 2 can be but is not limited to 0.6 mm 2 , 0.8 mm 2 , 1.0 mm 2 , 2.0 mm 2 , 3.0 mm2 , 4.0 mm 2 , 6.0 mm 2 , 8.0 mm 2 , 10.0 mm 2 , 12.0 mm 2 , 14.0 mm 2 , 16.0 mm 2 , 18.0 mm 2 , 20.0 mm 2 , 22.0 mm 2 , 23.53 mm 2 etc.

[0062] In this embodiment, when the k 2 value is too low, it is necessary to make the ratio of cyclic carbonates to linear carbonates in the electrolyte lower, the diameter L of the central hole 13, and the distance d between the roots of adjacent tabs 112 smaller; when the ratio of cyclic carbonates to linear carbonates in the electrolyte is too low, the dissociation ability of the electrolyte decreases, and at the same time, the proportion of low-boiling linear carbonates is relatively high, which is likely to exacerbate the consumption and gas generation of the electrolyte at high temperatures, resulting in capacity loss of the cylindrical battery 100 and affecting the life of the cylindrical battery 100; when the diameter L of the central hole 13 is too small and the distance d between the roots of adjacent tabs 112 is too low, the electrolyte injection and infiltration channels are insufficient and the infiltration is not sufficient.

[0063] In this embodiment, when the k 2 value is too high, it is necessary to make the ratio of cyclic carbonates to linear carbonates in the electrolyte larger, the diameter L of the central hole 13, and the distance d between the roots of adjacent tabs 112 larger; the larger the ratio A of cyclic carbonates to linear carbonates, the higher the mass proportion of cyclic carbonates in the electrolyte, the increase in electrolyte viscosity, insufficient infiltration of the electrode tab 11, and at the same time, it also deteriorates the low-temperature freezing point, resulting in deterioration of the low-temperature performance of the cylindrical battery 100; at the same time, a wider design of the diameter L of the central hole 13 will squeeze the design area of the electrode tab 11, making the design of the electrode tab 11 tend to the high-compaction direction, affecting the infiltration of the electrode tab 11 and deteriorating the cycle performance; when the distance d between the roots of adjacent tabs 112 is too large, although it is more beneficial for injection and infiltration, the area for welding the tabs 112 will be smaller, prone to poor welding and risk of false soldering.

[0064] The cylindrical battery 100 of the embodiment of the present application satisfies the relationship L·d = 10k 2 ·A. By designing the values of the relationship L·d = 10k 2 ·A and k 2 , the cylindrical battery 100 has better electrolyte wettability, so that the gram capacity of the cylindrical battery 100 can be better exerted, the cylindrical battery 100 has a higher normal-temperature cycle capacity retention rate, and thus has a higher normal-temperature cycle service life.

[0065] In some embodiments, the range of the mass fraction y wt% of the electrolyte salt in the electrolyte is: 8.75 wt% ≤ y wt% ≤ 16.2 wt%.

[0066] It can be understood that the range of the value of y is: 8.75 ≤ y ≤ 16.2.

[0067] Specifically, the mass fraction y wt% of the electrolyte salt in the electrolyte can be, but is not limited to, 8.75 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt%, 15 wt%, 15.5 wt%, 16 wt%, 16.2 wt%, etc.

[0068] In this embodiment, if the mass fraction of the electrolyte salt in the electrolyte is too low, the diffusion rate of electrolyte ions (such as lithium ions) is too low, the ionic conductivity of the electrolyte is too low, making the cylindrical battery 100 prone to polarization, resulting in lithium deposition, and reducing the kinetic performance and cycle capacity retention rate of the cylindrical battery 100; if the mass fraction of the electrolyte salt in the electrolyte is too high, the viscosity of the electrolyte increases, reducing the wetting ability of the electrolyte and the wettability of the electrolyte to the electrode assembly 10, thereby reducing the discharge capacity per gram of the cylindrical battery 100 and the cycle capacity retention rate of the cylindrical battery 100.

[0069] Please refer to Figure 3 , in some embodiments, the range of the distance d between two adjacent tabs 112 is: 1 mm ≤ d ≤ 5 mm.

[0070] Specifically, the distance d between two adjacent tabs 112 can be, but is not limited to, 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 1 mm, 3.3 mm, 3.5 mm, 3.8 mm, 1 mm, 4.3 mm, 4.5 mm, 4.8 mm, 5 mm.

[0071] In this embodiment, the distance between two adjacent tabs 112 in the cylindrical battery 100 is related to the size of the reserved pores after the electrode assembly 10 is wound, and the infiltration ability of the electrolyte after the cylindrical battery 100 is filled with liquid. The larger the distance d between two adjacent tabs 112, the stronger the infiltration ability of the electrolyte. Therefore, when the distance d between two adjacent tabs 112 is too small, the electrolyte is not easily permeated to the electrode tab 11 at the central position of the electrode assembly 10, which will reduce the infiltration ability of the electrolyte, affect the specific capacity of the electrode assembly 10, and reduce the cycle capacity retention rate of the cylindrical battery 100. When the distance d between two adjacent tabs 112 is too large, the area of the tab 112 is too narrow, which affects the welding area between the tab 112 and the current collector plate and the welding strength between the tab 112 and the current collector plate, and will make the current distribution between the electrode tabs 11 uneven, reduce the electron transfer speed on the electrode tab 11, cause the capacity of the cylindrical battery 100 not to be effectively exerted and lost, and reduce the kinetic performance of the cylindrical battery 100. In addition, it makes the resistance value of the welding area between the tab 112 and the current collector plate too low, increasing the risk of overcurrent fusing.

[0072] Optionally, the electrolyte salt may be a lithium salt.

[0073] Optionally, the lithium salt may include but is not limited to lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalato)borate (LiBOB), lithium difluorobis(oxalato)phosphate (LiODFP), lithium difluoro(oxalato)borate (LiODFB), lithium difluorophosphate (LiPO 2 F 2 ), lithium trifluoromethanesulfonate (CF 3 SO 3 Li), etc., at least one of them.

[0074] In some embodiments, the range of the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte is: 0.17 ≤ A ≤ 0.67.

[0075] Specifically, the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte may be but is not limited to 0.17, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.67, etc.

[0076] In this embodiment, if the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte is too low, the dissociation ability of lithium ions is reduced, the conductivity of the electrolyte is decreased, and thus the kinetic performance of the cylindrical battery 100 is reduced; increasing the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte can enable the electrolyte to have a higher ability to dissociate lithium ions, improve the conductivity of the electrolyte, and enhance the cycling performance of the cylindrical battery 100. However, when the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte is too high, it will affect the viscosity and freezing point of the electrolyte of the cylindrical battery 100, thereby increasing the difficulty of electrolyte infiltration of the cylindrical battery 100 and also reducing the cycling capacity retention rate of the cylindrical battery 100.

[0077] Optionally, the cyclic carbonate may include but is not limited to at least one of ethylene carbonate (abbreviated as EC), propylene carbonate (abbreviated as PC), etc. The dielectric constant of ethylene carbonate is much larger than that of propylene carbonate, and ethylene carbonate can better promote the formation of the solid electrolyte interface membrane (abbreviated as SEI).

[0078] Optionally, the linear carbonate may include but is not limited to at least one of dimethyl carbonate (abbreviated as DMC), diethyl carbonate (abbreviated as DEC), ethyl methyl carbonate (abbreviated as EMC), etc.

[0079] Optionally, the organic solvent further includes at least one of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, γ-butyrolactone, and 2,2-difluoroethyl acetate. In the organic solvent, the total mass fraction of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, γ-butyrolactone, and 2,2-difluoroethyl acetate is 0 to 20 wt%; specifically, it may be but is not limited to 0, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 13 wt%, 15 wt%, 18 wt%, 20 wt%, etc.

[0080] Optionally, in the electrolyte, the mass fraction of the organic solvent is 60 wt% to 85 wt%. Specifically, it may be but is not limited to 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, etc.

[0081] Optionally, the electrolyte further includes a film-forming additive. When the cylindrical battery 100 is a lithium-ion battery, the film-forming additive can be used to promote the formation of the interface membrane of at least one of the positive electrode plate 11a and the negative electrode plate 11b and maintain the stability of the interface membrane.

[0082] Optionally, the film-forming additive may include, but is not limited to, at least one of propargyl benzenesulfonic acid, vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfite (DTD), methylene methanedisulfonate (MMDS), butylsulfonic acid lactone (BS), 1,3-propylene sulfonic acid lactone (PST), etc.

[0083] Optionally, the mass fraction of the film-forming additive in the electrolyte ranges from 0.1 wt% to 10 wt%. Specifically, the mass fraction of the film-forming additive may be, but is not limited to, 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, etc.

[0084] Please refer to again Figure 2 , in some embodiments, the diameter L of the central hole 13 of the electrode assembly 10 ranges from 5 mm ≤ L ≤ 10 mm.

[0085] Specifically, the diameter L of the central hole 13 of the electrode assembly 10 may be, but is not limited to, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, etc.

[0086] In this embodiment, if the diameter L of the central hole 13 of the electrode assembly 10 is too small, the size of the channel reserved for the electrolyte in the electrode assembly 10 is too small, reducing the infiltration ability of the electrolyte, thereby affecting the discharge capacity of the electrode assembly 10 and reducing the cycle capacity retention rate of the battery; if the diameter L of the central hole 13 of the electrode assembly 10 increases, the infiltration area of the electrode assembly 10 can be increased and the infiltration ability of the electrolyte can be increased. However, if the diameter L of the central hole 13 of the electrode assembly 10 is too large, the volume energy density of the cylindrical battery 100 will be excessively reduced.

[0087] Please refer to together Figure 3 and Figure 4 , in some embodiments, the number of winding turns of the electrode assembly 10 is M turns, M turns include N steps 15, each step 15 includes multiple turns, each turn of the electrode tab 11 includes multiple tabs 112, the sizes of the multiple tabs 112 of each step 15 are the same, and in the direction from the outermost circle to the innermost circle of the electrode assembly 10, the widths of the tabs 112 of different steps 15 gradually decrease in a gradient manner and the heights of the tabs 112 of different steps 15 also gradually decrease in a gradient manner, where M > N.

[0088] It should be noted that the width of the tab 112 refers to the width of the tab 112 along the arrangement direction of the plurality of tabs 112. The height of the tab 112 refers to the height of the tab 112 along the direction perpendicular to the arrangement direction of the plurality of tabs 112 (i.e., along the arrangement direction of the tab 112 and the current collector 111).

[0089] It can be understood that the width of the tab 112 on the outermost step 15 is the largest and the height is the highest, and the width of the tab 112 on the step 15 closest to the central hole 13 is the smallest and the height is the lowest.

[0090] It can be understood that the widths of the plurality of tabs 112 on the same step 15 are equal and the heights are also equal.

[0091] It should be noted that among the plurality of tabs 112 on the electrode tab 11, the distance between any two adjacent tabs 112 is equal.

[0092] In this embodiment, by making the direction from the outermost circle to the innermost circle of the electrode assembly 10, the width of the tabs 112 on different steps 15 gradually decreases in a gradient manner and the height of the tabs 112 on different steps 15 also gradually decreases in a gradient manner. The gradient changes in the width and height of the tabs 112 on different steps 15 can enable better welding of the tabs 112 and the current collecting plate, improve the welding strength between the tabs 112 and the current collecting plate, easily make the current distribution on the current collector 111 uneven, reduce the electron transfer speed on the electrode tab 11, and reduce the dynamic performance of the cylindrical battery 100.

[0093] In some embodiments, the number N of steps 15 of the electrode assembly 10 ranges from: 2 ≤ N ≤ 10.

[0094] Specifically, the number N of steps 15 of the electrode assembly 10 can be, but is not limited to, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0095] In this embodiment, if the number N of steps 15 of the electrode assembly 10 is too small, the difficulty of die-cutting the tabs 112 is increased, and the amount of welding in the short tab 112 area (the area where the height of the tab 112 is smaller, that is, the tab 112 on the step 15 close to the central hole 13) becomes less. As a result, when the tab 112 is welded to the current collector 111, it is easy to have poor welding, resulting in virtual welding and reducing the preparation yield of the cylindrical battery 100; if the number N of steps 15 of the electrode assembly 10 is too large, the number of die-cut tabs 112 increases and the number of short tabs 112 increases, increasing the difficulty of die-cutting the tabs 112.

[0096] In some embodiments, the number n of tabs 112 of the electrode tab 11 ranges from: 400 ≤ n ≤ 2000.

[0097] It should be noted that n > M.

[0098] Understandably, the total number of tabs 112 on each electrode tab 11 ranges from 400 to 2000. For example, when the electrode tab 11 is the positive electrode tab 11a, the number of tabs 112 (i.e., the positive electrode tabs 112a) on the positive electrode tab 11a ranges from 400 to 2000. Another example is that when the electrode tab 11 is the negative electrode tab 11b, the number of tabs 112 (i.e., the negative electrode tabs 112b) on the negative electrode tab 11b ranges from 400 to 2000.

[0099] Specifically, the number n of tabs 112 on the electrode tab 11 can be, but is not limited to, 400, 450, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, etc.

[0100] In this embodiment, if the number of tabs 112 on the electrode tab 11 is too small, the width of each tab 112 is too wide. When welding the tab 112 to the current collector 111, it is easy to cause protrusions and wrinkles between adjacent die-cut tabs 112, which can easily lead to poor welding of the tab 112, and the tab 112 is bent and extruded inward, resulting in a short circuit in the electrical connection between the positive electrode tab 11a and the negative electrode tab 11b. In this embodiment, if the number of tabs 112 on the electrode tab 11 is too large, it increases the difficulty of the die-cutting process of the tab 112. When die-cutting the tab 112, the tab 112 is easily bent or broken, reducing the preparation yield of the electrode assembly 10.

[0101] In some embodiments, the height h1 of the tab 112 on the step 15 of the electrode assembly 10 closest to the central hole 13 ranges from 2 mm ≤ h1 ≤ 6 mm.

[0102] Understandably, on the electrode tab 11, the height h1 of the tab 112 with the minimum height ranges from 2 mm ≤ h1 ≤ 6 mm.

[0103] Specifically, the height h1 of the tab 112 on the step 15 of the electrode assembly 10 closest to the central hole 13 can be, but is not limited to, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, etc.

[0104] In this embodiment, if the height h1 of the tab 112 of the step 15 of the electrode assembly 10 closest to the central hole 13 is too low, it is likely to cause poor welding when the tab 112 of the innermost ring is welded to the current collector plate, resulting in uneven current density distribution of the current collector 111, slow electron transfer speed at the position of the current collector 111 of the electrode tab 11 close to the central hole 13, and reduction of the kinetic performance of the cylindrical battery 100; if the height h1 of the tab 112 of the step 15 of the electrode assembly 10 closest to the central hole 13 is too high, after the electrode assembly 10 is wound into a cylindrical shape, the tab 112 will be bent relative to the current collector 111 and then welded to the current collector plate. After the tab 112 is bent, the bent tab 112 is likely to overlap with the tabless area of the inner ring, so that the positive tab 112a overlaps with the negative current collector 111b or the negative tab 112b overlaps with the positive current collector 111a, resulting in a short circuit of the cylindrical battery 100.

[0105] In some embodiments, when the electrode assembly 10 is in a wound structure, the radial width w1 of the step 15 farthest from the central hole 13 ranges from 100 mm to 300 mm.

[0106] It can be understood that in the radial direction of the wound electrode assembly 10, among the N steps 15 of the electrode assembly 10, the width w1 of the outermost step 15 of the electrode assembly 10 ranges from 100 mm to 300 mm. It can also be understood that when the electrode assembly 10 is in a wound structure, the radial width w1 of the outermost step 15 ranges from 100 mm to 300 mm.

[0107] Specifically, when the electrode assembly 10 is in a wound structure, the radial width w1 of the step 15 farthest from the central hole 13 can be, but is not limited to, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, etc.

[0108] In this embodiment, if the radial width w1 of the step 15 of the electrode assembly 10 farthest from the central hole 13 is too small when the electrode assembly 10 is in a wound structure, it is likely to cause poor welding when the tab 112 on the outermost step 15 of the electrode assembly 10 is welded to the current collector plate; if the radial width w1 of the step 15 of the electrode assembly 10 farthest from the central hole 13 is too large, it is likely to cause insufficient welding of the tab 112 of the inner ring close to the central hole 13 to the current collector plate, resulting in uneven current density distribution of the current collector 111, slow electron transfer speed at the position of the current collector 111 of the electrode tab 11 close to the central hole 13, and reduction of the kinetic performance of the cylindrical battery 100.

[0109] Please refer toFigure 3 , in some embodiments, the electrode tab 11 includes a tabless region 14, the tabless region 14 is disposed close to the central hole 13 and connected to the step 15 closest to the central hole 13. When the electrode assembly 10 is flattened, the length s1 of the tabless region 14 ranges from 100 mm ≤ s1 ≤ 500 mm.

[0110] It should be noted that when the electrode assembly 10 is in a wound structure, the tabless region 14 is located within the innermost step 15, that is, the innermost step 15 surrounds the outer periphery of the tabless region 14.

[0111] Specifically, when the electrode assembly 10 is flattened, the length s1 of the tabless region 14 can be, but is not limited to, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, etc.

[0112] In this embodiment, when the length s1 of the tabless region 14 is too small when the electrode assembly 10 is flattened, after the electrode assembly 10 is formed, the tab 112 will be bent relative to the current collector 111 and then welded to the current collecting plate. After the tab 112 is bent, the innermost tab 112 is likely to overlap with the tabless region 14 after bending, so that the positive tab 112a overlaps with the negative current collector 111b or the negative tab 112b overlaps with the positive current collector 111a, resulting in a short circuit of the cylindrical battery 100. When the length s1 of the tabless region 14 is too large when the electrode assembly 10 is flattened, the welding area of the tab 112 on the step 15 closest to the central hole 13 of the electrode assembly 10 to the current collecting plate is insufficient, resulting in uneven current density distribution of the electrode tab 11 corresponding to the tabless region 14, and easy capacity loss of the cylindrical battery 100 during charge and discharge.

[0113] In some embodiments, the length s2 of the electrode tab 11 corresponding to the innermost step 15 of the electrode assembly 10 when flattened ranges from 300 mm ≤ s2 ≤ 500 mm.

[0114] It can be understood that the length s2 of the electrode tab 11 corresponding to the step 15 connecting the tabless region 14 when flattened ranges from 300 mm ≤ s2 ≤ 500 mm.

[0115] Specifically, the length s2 of the electrode tab 11 corresponding to the innermost step 15 of the electrode assembly 10 when flattened can be, but is not limited to, 300 mm, 320 mm, 340 mm, 360 mm, 380 mm, 400 mm, 420 mm, 440 mm, 460 mm, 480 mm, 500 mm, etc.

[0116] In this embodiment, when the length s2 of the electrode tab 11 corresponding to the innermost step 15 of the electrode assembly 10 is too short when flattened, it is likely that the welding of the tab 112 of the innermost step 15 to the current collector plate is insufficient, resulting in an overly long current passing path and too low current density for the electrode tab 11 corresponding to the innermost step 15; when the length s2 of the electrode tab 11 corresponding to the innermost step 15 of the electrode assembly 10 is too long, it is likely that when the tab 112 on the innermost step 15 of the electrode assembly 10 is bent, it will overlap with the electrode tab 11 in the tabless area 14, thus causing a short circuit between the positive electrode tab 11a and the negative electrode tab 11b.

[0117] Please refer to Figure 5 , optionally, the positive electrode tab 11a further includes a positive electrode active layer 113a, and the positive electrode active layer 113a is disposed on the surface of the positive electrode current collector 111a. It can be understood that the positive electrode active layer 113a can cover one surface or two opposite surfaces of the positive electrode current collector 111a.

[0118] It can be understood that the positive electrode tab 11a includes a positive electrode current collector 111a, a positive electrode tab 112a, and a positive electrode active layer 113a.

[0119] Optionally, the positive electrode current collector 111a can be, but is not limited to, an aluminum sheet.

[0120] Optionally, the positive electrode active layer 113a includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a positive electrode thickening agent.

[0121] Optionally, the positive electrode active material can be, but is not limited to, lithium iron phosphate.

[0122] Optionally, the positive electrode conductive agent can be, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, carbon fibers, graphene, etc.

[0123] Optionally, the positive electrode binder can be, but is not limited to, at least one of polyvinylidene fluoride (abbreviated as PVDF), polyamide (abbreviated as PA), polyacrylonitrile (abbreviated as PAN), polyacrylate, polyvinylether, polymethylmethacrylate (abbreviated as PMMA), polyhexafluoropropylene, polymerized styrene butadiene rubber (abbreviated as SBR), etc.

[0124] Optionally, in the positive electrode active layer 113a, the mass fraction of the positive electrode binder ranges from 2 wt% to 4 wt%. Specifically, in the positive electrode active layer 113a, the mass fraction of the positive electrode binder can be, but is not limited to, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, etc. If the mass fraction of the positive electrode binder is too small, the positive electrode active layer 113a is likely to powder or shed; if the mass fraction of the positive electrode binder is too large, the energy density of the positive electrode sheet 11a is reduced.

[0125] Optionally, the positive electrode thickener can be, but is not limited to, at least one of sodium carboxymethyl cellulose (abbreviated as CMC), polyacrylamide (PAM), polymethacrylate (PMA), etc.

[0126] Optionally, the separator 12 can be, but is not limited to, at least one of a polypropylene film (abbreviated as PP film), a polyethylene film (abbreviated as PE film), a ceramic separator 12, etc.

[0127] Optionally, the thickness of the separator 12 is 14 μm to 18 μm. Specifically, the thickness of the separator 12 can 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, etc.

[0128] Please refer to Figure 6 , optionally, the negative electrode sheet 11b further includes a negative electrode active layer 113b, and the negative electrode active layer 113b is disposed on the surface of the negative electrode current collector 111. It can be understood that the negative electrode active layer 113b can cover one surface or two opposite surfaces of the negative electrode current collector 111.

[0129] It can be understood that the negative electrode sheet 11b includes a negative electrode current collector 111b, a negative electrode tab 112b, and a negative electrode active layer 113b.

[0130] Optionally, the negative electrode current collector 111 can be, but is not limited to, a copper sheet.

[0131] Optionally, the negative electrode active layer 113b includes a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and a negative electrode thickener.

[0132] Optionally, the negative electrode active material can be, but is not limited to, graphite.

[0133] Optionally, the negative electrode conductive agent can be, but is not limited to, at least one of conductive carbon black (abbreviated as SP), acetylene black, carbon nanotubes, carbon fibers, graphene, etc.

[0134] Optionally, the negative electrode binder may be, but is not limited to, at least one of polyvinylidene fluoride, polyamide, polyacrylonitrile, polyacrylate, polyethylene ether, polymethyl methacrylate, polyhexafluoropropylene, styrene-butadiene rubber, etc.

[0135] Optionally, in the negative electrode active layer 113b, the mass fraction of the negative electrode binder ranges from 2 wt% to 4 wt%. Specifically, in the negative electrode active layer 113b, the mass fraction of the negative electrode binder may be, but is not limited to, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, etc. If the mass fraction of the negative electrode binder is too small, the negative electrode active layer 113b is likely to powder or shed; if the mass fraction of the negative electrode binder is too large, the energy density of the negative electrode sheet 11b is reduced.

[0136] Optionally, the negative electrode thickener may be, but is not limited to, at least one of sodium carboxymethyl cellulose (abbreviated as CMC), polyacrylamide (PAM), and polymethacrylate (PMA), etc.

[0137] Please refer to again Figure 1 and Figure 2 , optionally, the cylindrical battery 100 further includes a housing 20 and an end cap assembly 30. The housing 20 and the end cap assembly 30 enclose a receiving cavity (not shown in the figure), and the receiving cavity is used to receive the electrolyte, the positive electrode sheet 11a, the separator 12, and the negative electrode sheet 11b as described above.

[0138] The following further introduces the cylindrical battery 100 of the present application through specific examples.

[0139] Examples 1 to 21, Comparative Examples 1 to 4

[0140] The batteries of each example and comparative example are prepared through the following steps:

[0141] (1) Preparation of electrolyte: In an argon atmosphere glove box with a water content ≤ 1 ppm, according to the designed proportion of solvents, a mixed solution of ethylene carbonate (EC, cyclic carbonate), ethyl methyl carbonate (EMC, chain carbonate), and dimethyl carbonate (DMC, chain carbonate) solvents was prepared, with the mass ratio of DMC / EMC being DMC / EMC = 2; after sealing to isolate water, it was placed in a 0 °C freezer for 2 h, then taken out and quickly transferred to the glove box, and lithium hexafluorophosphate, the electrolyte salt, was added and stirred until the solute was completely dissolved and homogenized. After the temperature stabilized, vinylene carbonate (VC, mass fraction 3 wt%) and fluoroethylene carbonate (FEC, mass fraction 1.5 wt%), the film-forming additives, were added and mixed evenly to obtain the electrolyte. In the electrolytes of each example and comparative example, the mass ratio A of cyclic carbonate to chain carbonate was A = EC:(EMC + DMC) as shown in Table 1 below; in the electrolytes of each example and comparative example, the mass fraction of lithium hexafluorophosphate was as shown in Table 1 below.

[0142] (2) Preparation of the positive electrode sheet 11a: The positive electrode active material lithium iron phosphate (LiFePO 4 )), conductive carbon black (Super-P, positive electrode conductive agent), and PVDF (positive electrode binder) were mixed in a mass ratio of 94:3:3; then N-methylpyrrolidone (NMP) was added as a solvent to prepare a positive electrode slurry with a solid content of 60 wt% and stirred evenly. Then the positive electrode slurry was evenly coated on one surface of a 10-μm-thick positive electrode current collector 111a aluminum foil, and after drying, cold pressing, slitting, and die-cutting, the positive electrode sheet 11a to be wound was obtained; the single-sided thickness of the positive electrode active layer was 100 μm.

[0143] (3) Preparation of the negative electrode sheet 11b: The negative electrode active material artificial graphite, sodium carboxymethyl cellulose (CMC, thickener), conductive carbon black (Super-P, negative electrode conductive agent), and styrene-butadiene rubber latex (SBR, negative electrode binder) 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 6-μm-thick negative electrode current collector 111b copper foil, and after drying, cold pressing, slitting, and die-cutting, the negative electrode sheet 11b to be wound was obtained; the single-sided thickness of the negative electrode active layer was 70 μm.

[0144] (4) Preparation of the separator 12: A 16-μm-thick polyethylene film (PE) was used as the separator 12.

[0145] (5) Assembly of the cylindrical battery 100: Stack the above-mentioned positive electrode plate 11a, separator 12, and negative electrode plate 11b in sequence, with the separator 12 positioned between the positive electrode plate 11a and the negative electrode plate 11b to play an isolating role, and then wind them into a cylindrical bare battery core; after welding the tab 112, place the bare battery in the outer packaging case, inject the above-mentioned electrolyte after drying, and go through processes such as normal temperature standing, formation, second injection, aging, welding, helium leak detection, capacity and OCV testing, etc., to finally prepare the cylindrical battery 100. Among them, the number of winding turns M of the electrode assembly 10 of the cylindrical battery 100 is 80, the M turns include N steps 15, and the number N of the steps 15 of the electrode assembly 10 is 5; the number n of the tabs 112 of the electrode plate 11 is 1600; the height h1 of the tab 112 of the step 15 closest to the central hole 13 of the electrode assembly 10 is 4 mm; when the electrode assembly 10 is in a wound structure, the radial width w1 of the step 15 farthest from the central hole 13 is 200 mm; the tabless area 14 is arranged close to the central hole 13 and is connected to the step 15 closest to the central hole 13. When the electrode assembly 10 is flattened, the length s1 of the tabless area 14 is 300 mm; the length s2 of the electrode plate 11 corresponding to the innermost step 15 of the electrode assembly 10 when flattened is 350 mm.

[0146] The diameters L of the central holes 13 and the distances d between adjacent tabs 112 of the cylindrical batteries 100 in each example and comparative example are shown in Table 1 below.

[0147] Perform the following performance tests on the cylindrical batteries 100 in each example and comparative example:

[0148] (1) Wettability test: Use the cylindrical battery 100 designed in the examples and comparative examples that is qualified in baking and not filled with electrolyte. Manually inject 180 ± 3 g of the verification electrolyte into the cylindrical battery 100 from the liquid injection port through a syringe, record the electrolyte injection volume as m1, and insert a formation nail for sealing; then stand it in a stable environment at a high temperature of 45 °C for 10 h, disassemble the cylindrical battery 100, pour out the free electrolyte and record the weight m2 of the free electrolyte; the electrolyte wetting amount = electrolyte injection volume - free electrolyte amount (m = m1 - m2).

[0149] (2) Charge and discharge cycle test: The cylindrical batteries 100 of each example and comparative example were subjected to a constant current charge and discharge cycle test on a Blue Electric Tester. The test temperature was 25 °C, the charge and discharge rate was 1C, and the charge and discharge voltage window was 2.5V to 3.65V. The capacity retention rate after 500 cycles was calculated. The calculation formula was: Capacity retention rate after the 500th cycle = (Discharge capacity after the 500th cycle / Discharge capacity of the first cycle) × 100%. Among them, usually, a complete charge and discharge is called a charge and discharge cycle, that is, the battery is first charged from 2.5V to 3.65V, and then discharged from 3.65V to 2.5V, thus forming a charge and discharge cycle. Cycling 500 times means repeating the above process 500 times.

[0150] (3) Capacity test: The prepared cylindrical battery 100 was placed in a constant temperature test cabinet at 45 °C. It was charged to 3.65V at 0.33C and then discharged to 2.5V at 0.33C. It was cycled three times for charge and discharge within the range of 2.5V to 3.65V, and the discharge capacity of the third cycle was measured.

[0151] (4) Spacing d between the roots of adjacent tabs 112: The die-cutting equipment cut out the requirements of the designed tabs 112 on the full tabs 112 through program control. The spacing between the roots of the die-cut tabs 112 could be read directly through the die-cutting equipment or measured using a film ruler for the spacing between the roots of the trapezoidal tabs 112.

[0152] (5) Diameter L of the central hole 13: The electrode assembly 10 was wound by a winding needle, and the value of L could be measured using a digital display vernier caliper.

[0153] The parameters of the cylindrical batteries 100 of each example and comparative example are shown in Table 1 below.

[0154] Table 1 Parameters of the cylindrical batteries 100 of each example and comparative example

[0155]

[0156]

[0157] From the test results of Examples 1 to 5 in Table 1, it can be seen that as the mass ratio A of cyclic carbonate to linear carbonate in the electrolyte increases and as k 2 decreases, the wetting amount of the electrolyte of the cylindrical battery 100 gradually decreases, the discharge capacity of the cylindrical battery 100 first gradually increases and then gradually decreases, and the cycle capacity retention rate of the cylindrical battery 100 after 500 cycles at room temperature (25 °C) first gradually increases and then gradually decreases. Therefore, when 0.17 ≤ A ≤ 0.67 and 0.6 ≤ k 2When it is ≤ 23.53, the cylindrical battery 100 can have a high electrolyte infiltration amount, a high discharge capacity, and a high cycle capacity retention rate.

[0158] From the test results of Examples 3, 6 to 10 in Table 1, it can be seen that as the diameter L of the central hole 13 of the electrode assembly 10 increases and as k 1 and k 2 increase, the infiltration amount of the electrolyte of the cylindrical battery 100 first gradually increases and then gradually decreases, the discharge capacity of the cylindrical battery 100 first gradually increases and then gradually decreases, and the cycle capacity retention rate of the cylindrical battery 100 after 500 cycles at room temperature (25 °C) first gradually increases and then gradually decreases. Therefore, when 4 ≤ L ≤ 10, 3.76 ≤ k 1 ≤ 17.14 and 0.6 ≤ k 2 ≤ 23.53, the cylindrical battery 100 can have a high electrolyte infiltration amount, a high discharge capacity, and a high cycle capacity retention rate.

[0159] From the test results of Examples 3, 11 to 15 in Table 1, it can be seen that as the distance d between adjacent tabs 112 gradually increases and as k 1 and k 2 increase, the infiltration amount of the electrolyte of the cylindrical battery 100 gradually increases, the discharge capacity of the cylindrical battery 100 first gradually increases and then gradually decreases, and the cycle capacity retention rate of the cylindrical battery 100 after 500 cycles at room temperature (25 °C) first gradually increases and then gradually decreases. Therefore, when 1 ≤ d ≤ 5, 3.76 ≤ k 1 ≤ 17.14 and 0.6 ≤ k 2 ≤ 23.53, the cylindrical battery 100 can have a high electrolyte infiltration amount, a high discharge capacity, and a high cycle capacity retention rate.

[0160] From the test results of Comparative Example 1 in Table 1, it can be seen that when the diameter L of the central hole 13 of the electrode assembly 10 is too small and the distance d between two adjacent tabs 112 is zero (i.e., there is no distance), k 1 and k 2 are also both too small, so that the infiltration amount of the electrolyte of the cylindrical battery 100 is reduced to a large extent, and the discharge capacity and cycle capacity retention rate of the cylindrical battery 100 are also reduced.

[0161] From the test results of Comparative Example 2 in Table 1, it can be seen that when both the diameter L of the central hole 13 of the electrode assembly 10 and the distance d between two adjacent tabs 112 are too large, k 2is also too large, resulting in a significant reduction in the wetting amount of the electrolyte of the cylindrical battery 100, and also reducing the discharge capacity and the cycle capacity retention rate of the cylindrical battery 100. However, compared with Comparative Example 1, the wetting amount of the electrolyte and the cycle capacity retention rate of Comparative Example 2 are both higher.

[0162] From the test results of Examples 3, 16 to 21 in Table 1, it can be seen that as the mass fraction y of the electrolyte salt in the electrolyte increases, and as k 1 decreases, the wetting amount of the electrolyte of the cylindrical battery 100 gradually decreases, the discharge capacity of the cylindrical battery 100 first gradually increases and then gradually decreases, and the cycle capacity retention rate of the cylindrical battery 100 after 500 cycles at room temperature (25 °C) first gradually increases and then gradually decreases. Therefore, when 8.75 wt% ≤ y ≤ 16.2 wt% and 3.76 ≤ k 1 ≤ 17.14, the cylindrical battery 100 can have a high wetting amount of the electrolyte, a high discharge capacity, and a high cycle capacity retention rate.

[0163] From the test results of Comparative Example 3 in Table 1, it can be seen that when both the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte and the mass fraction y of the electrolyte salt in the electrolyte are too low, the wetting amount of the electrolyte of the cylindrical battery 100 and the discharge capacity of the cylindrical battery 100 are both high, but the 500-cycle capacity retention rate of the cylindrical battery 100 is significantly reduced.

[0164] From the test results of Comparative Example 4 in Table 1, it can be seen that when the mass ratio A of the cyclic carbonate to the linear carbonate in the electrolyte, the mass fraction y of the electrolyte salt in the electrolyte, the diameter L of the central hole 13 of the electrode assembly 10, and the distance d between two adjacent tabs 112 are all too small, k 1 is also too small, then the wetting amount of the electrolyte of the cylindrical battery 100, the discharge capacity of the cylindrical battery 100, and the cycle capacity retention rate are all reduced.

[0165] In summary, the cylindrical battery 100 of the embodiment of the present application has a high wetting amount of the electrolyte, the wetting amount of the electrolyte is greater than or equal to 145 g, and even 166 g can be obtained. The cylindrical battery 100 of the embodiment of the present application also has a high discharge capacity, the discharge capacity is greater than or equal to 50.13. The cylindrical battery 100 of the embodiment of the present application also has a high cycle capacity retention rate, and the room temperature cycle capacity retention rate is all greater than or equal to 90.1%, and even can reach 96.54%.

[0166] Please refer to Figure 7 , the embodiment of the present application also provides an energy storage device 200, which includes a box body 210 and a plurality of the cylindrical batteries 100 described in the embodiment of the present application, and the plurality of cylindrical batteries 100 are received in the box body 210.

[0167] Understandably, multiple cylindrical 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, in a series-parallel combination). The application does not specifically limit the connection method of multiple cylindrical batteries 100 of the same energy storage device 200.

[0168] Optionally, the energy storage device 200 can be at least one of a small energy storage box, a large energy storage cabinet, an energy storage module, etc. The application does not specifically limit the form of the energy storage device 200. The form of the energy storage device 200 in the application is only one of its many forms and should not be understood as a limitation on the energy storage device 200 in the application.

[0169] It should be noted that the stacking arrangement of the multiple cylindrical batteries 100 can be that the multiple cylindrical batteries 100 are arranged in abutting sequence, or the multiple cylindrical batteries 100 are arranged in sequence and at intervals. In addition, the multiple cylindrical batteries 100 can be stacked in the horizontal direction (such as the horizontal direction) or the vertical direction (such as the gravity direction). The stacking method and stacking direction of the multiple cylindrical batteries 100 can be designed according to the actual situation.

[0170] Understandably, the box body 210 has a receiving cavity (not shown in the figure), and the multiple cylindrical batteries 100 are received in the receiving cavity. In some embodiments, each receiving cavity receives one cylindrical battery 100. In other embodiments, each receiving cavity receives multiple cylindrical batteries 100.

[0171] Please refer to Figure 8 and Figure 9 , the embodiment of the application also provides an energy storage system 300, which includes the energy storage device 200 described in the embodiment of the application; and a power conversion device 310, the power conversion device 310 is electrically connected to the energy storage device 200, and the power 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.

[0172] The application scenarios of energy storage (i.e., energy storage) are relatively wide, including power generation side energy storage, grid side energy storage, and user side energy storage, etc. The energy storage system 300 in the embodiment of the application takes the power generation side energy storage as an example to introduce the energy storage system 300 in the embodiment of the application in detail, and should not be understood as a limitation on the energy storage system 300 in the embodiment of the application, nor should it be understood as a limitation on the energy storage device 200 and the cylindrical battery 100 in the embodiment of the application.

[0173] Optionally, the power conversion device 310 can convert at least one of other forms of energy such as solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electric energy.

[0174] Optionally, the number of the power conversion devices 310 may be one or more. When there are multiple power conversion devices 310, the multiple power conversion devices 310 may be connected in series, in parallel, or in a hybrid connection. This application does not make specific limitations in this regard.

[0175] Optionally, the power conversion device 310 may be, but is not limited to, at least one of a photovoltaic panel, a wind power generation device, a water power generation device, etc.

[0176] Optionally, the number of the energy storage devices 200 may be one or more. When there are multiple energy storage devices 200, the multiple energy storage devices 200 are connected in series or in parallel with each other. This application does not make specific limitations in this regard.

[0177] During operation, the power conversion device 310 is used to convert other forms of energy into electric energy and store it in the energy storage device 200. The electric energy stored in the energy storage device 200 can be supplied to electrical loads such as street lamps and household appliances for use during peak electricity prices, or for power supply when the power grid is powered off / out of power. The electric energy generated by the power conversion device 310 can also be supplied to the power grid through high-voltage cables to relieve the power supply pressure during peak periods of the power grid.

[0178] In this application, the mention of "embodiment" or "implementation manner" means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in this application may be combined with other embodiments. In addition, it should also be understood that the features, structures, or characteristics described in each embodiment of this application can be combined arbitrarily without contradiction to form another embodiment that does not deviate from the spirit and scope of the technical solution of this application.

[0179] Finally, it should be noted that the above implementation manners are only used to illustrate the technical solution of this application and not to limit it. Although this application has been described in detail with reference to the above preferred implementation manners, those of ordinary skill in the art should understand that the technical solution of this application can be modified or equivalently replaced without departing from the spirit and scope of the technical solution of this application.

Claims

1. A cylindrical battery, characterized in that: The cylindrical battery comprises: An electrolyte, the electrolyte comprising an electrolyte salt and an organic solvent, wherein the mass fraction of the electrolyte salt in the electrolyte is y wt %; and An electrode assembly, the electrode assembly comprising an electrode plate, the electrode plate comprising an electrically connected current collector and a plurality of tabs, the plurality of tabs being arranged at intervals on the same side of the current collector, and a spacing d between two adjacent tabs; the electrode assembly is in a winding structure, the electrode assembly having a central hole, and a diameter of the central hole of the electrode assembly is L, wherein the unit of d is mm, and the unit of L is mm; The battery also satisfies the relationship: d=10k1·yL, wherein the range of k1 is 3.7mm≤k1≤17.14mm.

2. The cylindrical battery according to claim 1, characterized in that: The organic solvent includes a cyclic carbonate and a chain carbonate, and the mass ratio of the cyclic carbonate to the chain carbonate in the electrolyte is A; The battery satisfies the relationship: L·d=10k2·A, where the range of k2 is 0.6mm 2 ≤k2≤23.53mm 2 .

3. The cylindrical battery according to claim 1, characterized in that: The mass fraction y wt % of the electrolyte salt in the electrolyte is in the range of 8.75 wt % ≤ y wt % ≤ 16.2 wt %.

4. The cylindrical battery according to claim 1 or 2, characterized in that: The range of the distance d between two adjacent tabs is: 1mm≤d≤5mm.

5. The cylindrical battery according to claim 1 or 2, characterized in that: The diameter L of the central hole of the electrode assembly is in the range of 5 mm≤L≤10 mm.

6. The cylindrical battery according to claim 2, characterized in that: The mass ratio A of the cyclic carbonate to the chain carbonate in the electrolyte is in the range of 0.17≤A≤0.

67.

7. The cylindrical battery according to claim 1, characterized in that: The number of turns of the electrode assembly is M, M turns include N steps, each step includes multiple turns, the electrode plate of each turn includes multiple pole ears, the multiple pole ears of each step have the same size, and from the outermost turn of the electrode assembly to the innermost turn, the width of the pole ears at different steps gradually decreases and the height of the pole ears at different steps also gradually decreases, wherein M>N.

8. The cylindrical battery according to claim 7, characterized in that: The number N of steps of the electrode assembly is in the range of 2≤N≤10.

9. The cylindrical battery according to claim 7, characterized in that: The number n of the electrode tabs of the electrode plate is in the range of 400≤n≤2000.

10. The cylindrical battery according to claim 7, characterized in that: The height h1 of the electrode tab of the step of the electrode assembly closest to the central hole is in the range of 2 mm ≤ h1 ≤ 6 mm.

11. The cylindrical battery according to claim 7, characterized in that: When the electrode assembly is in a winding structure, the radial width w1 of the step farthest from the central hole is in the range of 100 mm≤w1≤300 mm.

12. The cylindrical battery according to claim 7, characterized in that: The electrode plate includes a non-polar lug area, which is arranged close to the central hole and connected to the step closest to the central hole. When the electrode assembly is flattened, the length s1 of the non-polar lug area is in the range of 100mm≤s1≤500mm.

13. The cylindrical battery according to claim 7, characterized in that: The length s2 of the electrode pole piece corresponding to the innermost step of the electrode assembly when flattened is in the range of: 300mm≤s2≤500mm.

14. An energy storage device, characterized in that: include: Box; as well as A plurality of cylindrical batteries according to any one of claims 1 to 13, wherein the plurality of cylindrical batteries are housed in the box.

15. An energy storage system, characterized in that: include: The energy storage device according to claim 14; as well as An electric energy conversion device, 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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