Non-aqueous electrolyte and secondary battery and electronic device containing same

Abstract

The invention provides a non-aqueous electrolyte and a secondary battery and an electronic device containing the non-aqueous electrolyte, the non-aqueous electrolyte comprises fluorosulfonamide as shown in a formula I and sulfonamide lithium salt as shown in a formula II, R1 is selected from fluorine atoms or C1-C5 alkyl groups at least partially substituted by fluorine; r2 and R3 are independently selected from alkyl groups of C1 to C5, and R2 and R3 can be connected through a single bond to form a ring; r4 and R5 are independently selected from fluorine atoms, alkyl groups of C1 to C5, alkyl groups of C1 to C5 at least partially substituted by fluorine, or alkoxy groups of C1 to C5 at least partially substituted by fluorine. By regulating and controlling the non-aqueous electrolyte provided by the invention to meet the characteristics, the low-temperature discharge performance and high-temperature storage performance of the secondary battery can be improved.

Description

Technical Field

[0001] The present application relates to the field of electrochemical technologies, and particularly to a non-aqueous electrolyte, a secondary battery containing the same, and an electronic device. Background Art

[0002] Lithium-ion batteries have significant advantages such as high energy density, miniaturization, and light weight, and are widely used in mobile phones, laptops, tablets, drones, electric vehicles, power tools, power storage systems, etc. Generally, a lithium-ion battery consists of a positive electrode sheet, a negative electrode sheet, and an electrolyte. The electrolyte is responsible for maintaining the ion transport between the positive electrode sheet and the negative electrode sheet, and also for maintaining a stable interface to enable the lithium-ion battery to work stably.

[0003] The prior art improves the energy density of lithium-ion batteries by using electrode materials with high specific capacity, such as silicon-based materials. However, after lithiation, the silicon-based material forms a lithium-silicon alloy, which has a highly reactive nature and extremely easily attacks the solvent molecules in the electrolyte, resulting in rapid consumption of the electrolyte and loss of active lithium. Therefore, there are problems of poor low-temperature discharge performance and poor high-temperature storage performance. There is an urgent need in the market for a lithium-ion battery with both good low-temperature discharge performance and high-temperature storage performance. Summary of the Invention

[0004] The purpose of the present application is to provide a non-aqueous electrolyte, a secondary battery containing the same, and an electronic device to improve the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0005] The present application provides a non-aqueous electrolyte, which includes a fluorosulfonamide represented by Formula I and a lithium sulfonamide salt represented by Formula II:

[0006]

[0007] Wherein, R1 is selected from a fluorine atom or a C1-C5 alkyl group at least partially substituted by fluorine; R2 and R3 are each independently selected from C1-C5 alkyl groups, and R2 and R3 can be connected by a single bond to form a ring; R4 and R5 are each independently selected from a fluorine atom, a C1-C5 alkyl group, a C1-C5 alkyl group at least partially substituted by fluorine, or a C1-C5 alkoxy group at least partially substituted by fluorine. The fluorosulfonamide and the lithium sulfonamide salt in the non-aqueous electrolyte act synergistically to preferably reduce the gas generation problem of the lithium sulfonamide salt in a high-temperature environment, enabling the secondary battery to have both good low-temperature discharge performance and high-temperature storage performance.

[0008] In some embodiments of the present application, the fluorosulfonamide represented by Formula I includes at least one of the following compounds:

[0009]

[0010]

[0011] By selecting the fluorosulfonamide shown in the above formula I, and synergistically acting with the lithium salt of sulfonamide, the secondary battery can have good low-temperature discharge performance and high-temperature storage performance.

[0012] In some embodiments of the present application, the lithium salt of sulfonamide shown in formula II includes at least one of the following compounds:

[0013]

[0014] The lithium salt of sulfonamide shown in the above formula II has good dissociation ability at low temperature. Synergistically acting with the fluorosulfonamide, it can preferably reduce the gas generation problem of the lithium salt of sulfonamide in a high-temperature environment, enabling the secondary battery to have good low-temperature discharge performance and high-temperature storage performance simultaneously.

[0015] In some embodiments of the present application, R1 is selected from a fluorine atom or a trifluoromethyl group; R2 and R3 are each independently selected from a methyl group or an ethyl group; R2 and R3 are connected by a single bond to form a five-membered ring or a six-membered ring. By selecting the fluorosulfonamide that meets the above characteristics, the low-temperature discharge performance and high-temperature storage performance of the secondary battery can be further improved.

[0016] In some embodiments of the present application, R4 and R5 are each independently selected from a fluorine atom, a trifluoromethyl group, a methyl group, or a trifluoromethoxy group. By selecting the lithium salt of sulfonamide that meets the above characteristics, the lithium salt of sulfonamide has better low-temperature performance, and synergistically acting with the fluorosulfonamide can further improve the low-temperature discharge performance of the secondary battery.

[0017] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage content of the fluorosulfonamide is W I , 5% ≤ W I ≤ 60%, preferably, 10% ≤ W I ≤ 50%. By regulating the mass percentage content of the fluorosulfonamide within the above range, the fluorosulfonamide has a suitable content, enabling the secondary battery to have good low-temperature discharge performance and high-temperature storage performance simultaneously.

[0018] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage content of the lithium salt of sulfonamide is W II , 10% ≤ W II ≤ 40%, preferably, 15% ≤ W II ≤ 30%. By regulating the mass percentage content of the lithium salt of sulfonamide within the above range, the secondary battery can have good low-temperature discharge performance and high-temperature storage performance simultaneously.

[0019] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage content of fluorosulfonamide is W I , and the mass percentage content of lithium sulfonamide is W II , 30% ≤ W I + W II ≤ 60%. By regulating the relationship between W I and W II to satisfy the above characteristics, the mass percentage content of each component in the non-aqueous electrolyte can be further optimized, enabling fluorosulfonamide and lithium sulfonamide to produce a better synergistic effect, thereby further improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0020] In some embodiments of the present application, the non-aqueous electrolyte further includes a first component, and the first component includes at least one of fluorinated ethylene carbonate, difluorinated ethylene carbonate, vinylene carbonate, or ethylene vinylene carbonate. Based on the mass of the non-aqueous electrolyte, the mass percentage content of the first component is W III , 0.5% ≤ W III ≤ 15%, preferably, 1% ≤ W III ≤ 10%. By regulating the mass percentage content of the first component within the above range, a dense solid electrolyte interface (SEI) film can be formed on the negative electrode surface, thereby reducing the possibility of gas generation due to the reduction reaction of lithium sulfonamide at the negative electrode, improving the cycle stability of the secondary battery, and enabling the secondary battery to have good low-temperature discharge performance.

[0021] In some embodiments of the present application, 0.1 ≤ W III / (100% - (W I + W II )) ≤ 1. By regulating the mass percentage content of each component in the non-aqueous electrolyte to satisfy the above characteristics, the mass percentage content of each component in the non-aqueous electrolyte can be further optimized, and the first component can produce a better synergistic effect with fluorosulfonamide and lithium sulfonamide, thereby further improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0022] In some embodiments of the present application, the non-aqueous electrolyte further includes a second component, and the second component includes at least one of succinonitrile, glutaronitrile, methylglutaronitrile, adiponitrile, or 1,3,6-hexanetricarbonitrile. By selecting the above second component, a solid electrolyte interface film rich in inorganic components can be formed on the positive electrode surface in cooperation with fluorosulfonamide and lithium sulfonamide, reducing the side reaction between the positive electrode and the electrolyte in a high-voltage environment, thereby improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0023] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage of the second component is 0.5% to 5%. By adjusting the mass percentage of the second component within the above range, the second component can have an appropriate mass percentage, further improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0024] The second aspect of the present application provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and the non-aqueous electrolyte in any of the foregoing embodiments. Therefore, the secondary battery provided by the present application has good low-temperature discharge performance and high-temperature storage performance.

[0025] The third aspect of the present application provides an electronic device, which includes the secondary battery in any of the foregoing embodiments. Thus, the electronic device provided by the present application has good performance in use.

[0026] Advantages of the present application:

[0027] The present application provides a non-aqueous electrolyte and a secondary battery and an electronic device including the same. The non-aqueous electrolyte includes a fluorosulfonamide represented by Formula I and a lithium sulfonamide salt represented by Formula II: wherein, R1 is selected from a fluorine atom or a C1-C5 alkyl group at least partially substituted by fluorine; R2 and R3 are each independently selected from C1-C5 alkyl groups, and R2 and R3 may be connected by a single bond to form a ring; R4 and R5 are each independently selected from a fluorine atom, a C1-C5 alkyl group, a C1-C5 alkyl group at least partially substituted by fluorine, or a C1-C5 alkoxy group at least partially substituted by fluorine. By adjusting the non-aqueous electrolyte of the present application to meet the above characteristics, the fluorosulfonamide and the lithium sulfonamide salt in the non-aqueous electrolyte act synergistically, capable of improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0028] Of course, it is not necessary for any product or method implementing the present application to achieve all the above-mentioned advantages simultaneously. Detailed Embodiments

[0029] Next, the technical solutions in the present application will be clearly and completely described in conjunction with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0030] It should be noted that in the specific embodiments of the present application, a lithium-ion battery is used as an example of the secondary battery to explain the present application, but the secondary battery of the present application is not limited to lithium-ion batteries.

[0031] The present application provides a non-aqueous electrolyte, which includes a fluorosulfonamide represented by Formula I and a lithium sulfonamide salt represented by Formula II:

[0032]

[0033] Wherein, R1 is selected from a fluorine atom or a C1-C5 alkyl group at least partially substituted by fluorine; R2 and R3 are each independently selected from C1-C5 alkyl groups, and R2 and R3 may be linked by a single bond to form a ring; R4 and R5 are each independently selected from a fluorine atom, a C1-C5 alkyl group, a C1-C5 alkyl group at least partially substituted by fluorine, or a C1-C5 alkoxy group at least partially substituted by fluorine.

[0034] The inventors have found through research that lithium sulfonamide salts have good dissociation ability at low temperatures, so they can endow the electrolyte with good low-temperature performance. However, there is a problem of easy gas generation in a high-temperature environment, which affects the high-temperature performance of secondary batteries. Fluorosulfonamide can cooperate with lithium sulfonamide salts to form an interphase containing lithium fluoride and lithium sulfate at the interface. The interphase containing lithium fluoride and lithium sulfate can, on the one hand, maintain relatively fast ion conduction; on the other hand, the interphase composed of inorganic compounds is relatively stable and can assist the rapid desolvation of solvent molecules at the interface, and can preferably reduce the gas generation caused by the decomposition of solvent molecules. The non-aqueous electrolyte of the present application combines fluorosulfonamide with lithium sulfonamide salts. While lithium sulfonamide salts retain good low-temperature dissociation ability, by adding fluorosulfonamide, it cooperates with lithium sulfonamide salts to preferably reduce the gas generation problem of lithium sulfonamide salts in a high-temperature environment, enabling the secondary battery to have good low-temperature discharge performance and high-temperature storage performance at the same time.

[0035] In some embodiments of the present application, the fluorosulfonamide represented by Formula I includes at least one of the following compounds:

[0036]

[0037]

[0038] By selecting the fluorosulfonamide represented by Formula I above, an interphase containing lithium fluoride and lithium sulfate can be formed at the interface. While the interphase containing lithium fluoride and lithium sulfate maintains relatively fast ion conduction, it can cooperate with lithium sulfonamide salts to assist the rapid desolvation of lithium sulfonamide salts at the interface, and can preferably reduce the problem of gas generation of lithium sulfonamide salts in a high-temperature environment, enabling the secondary battery to have good low-temperature discharge performance and high-temperature storage performance.

[0039] In some embodiments of the present application, the lithium sulfonamide salt represented by Formula II includes at least one of the following compounds:

[0040]

[0041]

[0042] The lithium sulfonamide salt shown in Formula II above has good dissociation ability at low temperatures and, in synergistic action with fluorosulfonamide, can preferably reduce the gas generation problem of lithium sulfonamide salt in a high-temperature environment, enabling the secondary battery to have good low-temperature discharge performance and high-temperature storage performance simultaneously.

[0043] In some embodiments of the present application, R1 is selected from a fluorine atom or trifluoromethyl; R2 and R3 are each independently selected from methyl or ethyl; R2 and R3 are connected by a single bond to form a five-membered or six-membered ring. By selecting a fluorosulfonamide that satisfies the above characteristics, the fluorosulfonamide has better performance and can, in synergistic action with the lithium sulfonamide salt, preferably assist the rapid desolvation of the lithium sulfonamide salt at the interface, thereby reducing the problem of gas generation of the lithium sulfonamide salt in a high-temperature environment and further improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0044] In some embodiments of the present application, R4 and R5 are each independently selected from a fluorine atom, trifluoromethyl, methyl, or trifluoromethoxy. By selecting a lithium sulfonamide salt that satisfies the above characteristics, the lithium sulfonamide salt has better low-temperature performance and can, in synergistic action with the fluorosulfonamide, further improve the low-temperature discharge performance of the secondary battery.

[0045] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage content of the fluorosulfonamide is W I , 5% ≤ W I ≤ 60%, preferably, 10% ≤ W I ≤ 50%. For example, the value of W I can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or a range composed of any two of the above values. When the fluorosulfonamide has a suitable content, it can improve the problem that the viscosity of the non-aqueous electrolyte increases after adding the fluorosulfonamide and affects the ion transport efficiency of the secondary battery. At the same time, in synergistic action with the lithium sulfonamide salt, the fluorosulfonamide can preferably reduce the problem of gas generation of the lithium sulfonamide salt in a high-temperature environment. Therefore, by controlling the mass percentage content of the fluorosulfonamide within the above range, the secondary battery can have good low-temperature discharge performance and high-temperature storage performance simultaneously.

[0046] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage content of the lithium sulfonamide salt is W II , 10% ≤ W II ≤ 40%, preferably, 15% ≤ W II ≤ 30%. For example, the value of W IIThe value can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, or a range composed of any two of the above values. Lithium sulfonamide salt has good dissociation ability at low temperature. When the lithium sulfonamide salt has a suitable mass percentage content, on the one hand, it can better improve the ion migration rate of the secondary battery in a low-temperature environment and improve the low-temperature discharge performance of the secondary battery; on the other hand, it can reduce the risk of gas generation due to insufficient antioxidant properties of the non-aqueous electrolyte after adding the lithium sulfonamide salt. At the same time, the lithium sulfonamide salt can act synergistically with fluorosulfonamide to reduce the gas generation problem of the lithium sulfonamide salt in a high-temperature environment. Therefore, by controlling the mass percentage content of the lithium sulfonamide salt within the above range, the secondary battery can have good low-temperature discharge performance and high-temperature storage performance at the same time.

[0047] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage content of fluorosulfonamide is W I , and the mass percentage content of lithium sulfonamide salt is W II , 30% ≤ W I +W II ≤ 60%. For example, the value of W I +W II can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, or a range composed of any two of the above values. By controlling the relationship between W I and W II to satisfy the above characteristics, the mass percentage content of each component in the non-aqueous electrolyte can be further optimized, enabling fluorosulfonamide and lithium sulfonamide salt to have a better synergistic effect, thereby further improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0048] In some embodiments of the present application, the non-aqueous electrolyte further includes a first component, and the first component includes at least one of fluorovinyl carbonate, difluorovinyl carbonate, vinylene carbonate, or ethylene vinylene carbonate. Based on the mass of the non-aqueous electrolyte, the mass percentage content of the first component is W III , 0.5% ≤ W III ≤ 15%, preferably, 1% ≤ W III ≤ 10%. For example, the value of W III can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or a range composed of any two of the above values. By controlling the mass percentage content of the first component within the above range, a dense solid electrolyte interface (SEI) film can be formed on the negative electrode surface, thereby reducing the possibility of gas generation due to the reduction reaction of the lithium sulfonamide salt at the negative electrode, improving the cycle stability of the secondary battery, and enabling the secondary battery to have good low-temperature discharge performance.

[0049] In some embodiments of the present application, 0.1 ≤ W III / (100% - (W I + W II )) ≤ 1. For example, the value of W III / (100% - (W I + W II )) can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a range composed of any two of the above numerical values. By regulating the mass percentage content of each component in the non-aqueous electrolyte to meet the above characteristics, the mass percentage content of each component in the non-aqueous electrolyte can be further optimized, so that each component in the electrolyte has a better synergistic effect. The first component can preferably improve the dissociation effect of lithium sulfonamide salt in a low-temperature environment and improve the ion mobility; at the same time, the first component can form a dense SEI film on the surface of the negative electrode, which can preferably reduce the decomposition of the SEI film in a high-temperature environment and reduce the possibility of gas generation due to the reduction reaction of lithium sulfonamide salt at the negative electrode, thereby further improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0050] In some embodiments of the present application, the non-aqueous electrolyte further includes a second component, and the second component includes at least one of succinonitrile, glutaronitrile, methylglutaronitrile, adiponitrile or 1,3,6-hexanetricarbonitrile. By selecting the above second component, the positive electrode can be passivated, and the side reaction between the positive electrode and the non-aqueous electrolyte in a high-voltage environment can be reduced, thereby improving the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0051] In some embodiments of the present application, based on the mass of the non-aqueous electrolyte, the mass percentage content of the second component is 0.5% to 5%. For example, the mass percentage content of the second component can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or a range composed of any two of the above numerical values. The second component can passivate the positive electrode and reduce the side reaction between the positive electrode and the non-aqueous electrolyte in a high-voltage environment. By regulating the mass percentage content of the second component within the above range, the second component can have a suitable mass percentage content, and further improve the low-temperature discharge performance and high-temperature storage performance of the secondary battery.

[0052] In this application, the non-aqueous electrolyte may further include other lithium salts. There is no particular limitation on the other lithium salts in this application, as long as the objectives of this application can be achieved. For example, the other lithium salts may include, but are not limited to, at least one of LiPF6, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, Li2SiF6, or lithium difluoroborate. There is no particular limitation on the content of the other lithium salts in the electrolyte, as long as the objectives of this application can be achieved. For example, based on the mass of the non-aqueous electrolyte, the mass percentage content of the other lithium salts is 0% to 30%.

[0053] In this application, the non-aqueous electrolyte further includes other non-aqueous solvents. There is no particular limitation on the other non-aqueous solvents in this application, as long as the objectives of this application can be achieved. For example, the other non-aqueous solvents may include, but are not limited to, at least one of carbonate compounds, carboxylate compounds, ether compounds, or other organic solvents.

[0054] The above-mentioned carbonate compounds may include, but are not limited to, linear carbonate compounds or cyclic carbonate compounds. The above-mentioned linear carbonate compounds may include, but are not limited to, at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), or methyl ethyl carbonate (MEC). The above-mentioned cyclic carbonates may include, but are not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), or butylene carbonate (BC). The above-mentioned carboxylate compounds may include, but are not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolide, valerolactone, or caprolactone. The above-mentioned ether compounds may include, but are not limited to, at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran. The above-mentioned other organic solvents may include, but are not limited to, at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, or trioctyl phosphate. There is no particular limitation on the content of the other non-aqueous solvents in the non-aqueous electrolyte, as long as the objectives of this application can be achieved. For example, based on the mass of the non-aqueous electrolyte, the mass percentage content of the other non-aqueous solvents is 0% to 77%.

[0055] In this application, the characteristics of different components included in the above non-aqueous electrolyte can be combined, and the embodiments covered by the above combination are all within the protection scope of this application.

[0056] A second aspect of the present application provides a secondary battery, which includes a positive electrode plate, a negative electrode plate, a separator, and a non-aqueous electrolyte in any of the foregoing embodiments. Therefore, the secondary battery provided by the present application has good low-temperature discharge performance and high-temperature storage performance.

[0057] In the present application, the secondary battery further includes a positive electrode plate, and the positive electrode plate includes a positive electrode current collector and a positive electrode material layer provided on at least one surface of the positive electrode current collector. The above "positive electrode material layer provided on at least one surface of the positive electrode current collector" means that the positive electrode material layer can be provided on one surface of the positive electrode current collector along its own thickness direction, or can be provided on two surfaces of the positive electrode current collector along its own thickness direction. It should be noted that the "surface" here can be the entire area of the surface of the positive electrode current collector or a partial area of the surface of the positive electrode current collector. There is no particular limitation in the present application, as long as the purpose of the present application can be achieved.

[0058] The present application has no particular limitation on the positive electrode current collector, as long as the purpose of the present application can be achieved. For example, it can include aluminum foil, aluminum alloy foil, or a composite current collector (such as an aluminum-carbon composite current collector), etc.

[0059] The positive electrode material layer includes a positive electrode active material. The present application has no particular limitation on the positive electrode active material, as long as the purpose of the present application can be achieved. For example, the positive electrode active material can include, but is not limited to, at least one of lithium nickel cobalt manganese oxide (such as NCM811, NCM622, NCM523, NCM111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide (LiCoO2), lithium manganese oxide, lithium manganese iron phosphate, or lithium titanate.

[0060] The positive electrode material layer may further include a conductive agent and a binder. The present application has no particular limitation on the types of the conductive agent and the binder, as long as the purpose of the present application can be achieved. For example, the binder can include at least one of polyacrylate, polyimide, polyamide, polyamideimide, polyvinylidene fluoride, styrene-butadiene copolymer (styrene-butadiene rubber), sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium hydroxymethyl cellulose, or potassium hydroxymethyl cellulose. The conductive agent can include at least one of conductive carbon black, carbon nanotubes (CNTs), carbon fibers, flake graphite, or graphene, etc. The above conductive carbon black can be at least one of acetylene black, Super P, or Ketjenblack. The above carbon nanotubes can be at least one of single-walled carbon nanotubes or multi-walled carbon nanotubes. The above carbon fibers can be at least one of vapor-grown carbon fibers (VGCF) or nanofibers. The present application has no particular limitation on the mass ratio of the positive electrode active material, the conductive agent, and the binder in the positive electrode material layer. Those skilled in the art can select according to actual needs as long as the purpose of the present application can be achieved.

[0061] There is no particular limitation on the thickness of the positive current collector and the positive electrode material layer in this application, as long as the object of this application can be achieved. For example, the thickness of the positive current collector is 5 μm to 20 μm, and the thickness of the single-sided positive electrode material layer is 30 μm to 120 μm.

[0062] Optionally, the positive electrode sheet may further include a conductive layer, which is located between the positive current collector and the positive electrode material layer. There is no particular limitation on the composition of the conductive layer, and it can be a commonly used conductive layer in the art. The conductive layer includes a conductive agent and a binder. There is no particular limitation on the conductive agent and the binder in the conductive layer of this application. For example, it can be at least one of the above-mentioned conductive agents and the above-mentioned binders.

[0063] In this application, the secondary battery further includes a negative electrode sheet, which includes a negative current collector and a negative electrode material layer provided on at least one surface of the negative current collector. The above-mentioned "negative electrode material layer provided on at least one surface of the negative current collector" means that the negative electrode material layer can be provided on one surface of the negative current collector along its thickness direction, or can be provided on both surfaces of the negative current collector along its thickness direction. It should be noted that the "surface" here can be the entire area of the surface of the negative current collector, or a partial area of the surface of the negative current collector. There is no particular limitation in this application, as long as the object of this application can be achieved.

[0064] There is no particular limitation on the negative current collector in this application, as long as the object of this application can be achieved. For example, it can include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or composite current collector. Exemplarily, the composite current collector can be a lithium-copper composite current collector, a carbon-copper composite current collector, a nickel-copper composite current collector, a titanium-copper composite current collector, etc.

[0065] The negative electrode material layer includes a negative electrode active material. There is no particular limitation on the negative electrode active material in this application, as long as the object of this application can be achieved. For example, the negative electrode active material can include, but is not limited to, natural graphite, artificial graphite, mesophase carbon microspheres, hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, spinel-structured lithiated TiO2-Li4Ti5O 12 or at least one of Li-Al alloys.

[0066] In some embodiments of this application, the negative electrode material layer may further include a conductive agent and a binder. There is no particular limitation on the types of the conductive agent and the binder in this application, as long as the object of this application can be achieved. For example, it can be at least one of the above-mentioned conductive agents and the above-mentioned binders. There is no particular limitation on the mass ratio of the negative electrode active material, the conductive agent, and the binder in the negative electrode material layer, and those skilled in the art can select according to actual needs as long as the object of this application can be achieved.

[0067] There is no particular limitation on the thickness of the negative electrode material layer in the present application, as long as the object of the present application can be achieved. For example, the thickness of the single-sided negative electrode material layer is 30 μm to 120 μm.

[0068] There is no particular limitation on the thickness of the negative electrode current collector in the present application, as long as the object of the present application can be achieved. For example, the thickness of the negative electrode current collector is 4 μm to 15 μm.

[0069] Optionally, the negative electrode plate may further include a conductive layer, and the conductive layer is located between the negative electrode current collector and the negative electrode material layer. There is no particular limitation on the composition of the conductive layer in the present application, and it may be a commonly used conductive layer in the art. For example, the conductive layer includes a conductive agent and a binder. There is no particular limitation on the conductive agent and the binder in the conductive layer in the present application, and for example, it may be at least one of the above-mentioned conductive agents and the above-mentioned binders.

[0070] In the present application, the secondary battery further includes a separator. There is no particular limitation on the separator in the present application, as long as the object of the present application can be achieved. For example, the material of the separator may include, but is not limited to, at least one of polyolefins (PO) mainly composed of polyethylene (PE) and polypropylene (PP), polyesters (for example, polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex or aramid. The type of the separator may include at least one of a woven film, a non-woven film, a microporous film, a composite film, a rolled film or a spun film.

[0071] In some embodiments of the present application, the separator may include a base material layer and a surface treatment layer. The base material layer may be a non-woven fabric or a composite film having a porous structure, and the material of the base material layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric or a polypropylene-polyethylene-polypropylene porous composite film may be used.

[0072] Optionally, a surface treatment layer is provided on at least one surface of the base material layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.

[0073] In some embodiments of the present application, the inorganic layer comprises inorganic particles and a binder. There is no particular limitation on the inorganic particles in the present application. For example, the inorganic particles may include at least one of alumina, silica, magnesia, titania, hafnium dioxide, tin dioxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconia, yttria, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. There is no particular limitation on the binder in the present application. For example, the binder may be at least one of the above-mentioned binders. In some embodiments of the present application, the polymer layer comprises a polymer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, or poly(vinylidene fluoride - hexafluoropropylene).

[0074] In the present application, there is no particular limitation on the thickness of the separator, as long as the object of the present application can be achieved. For example, the thickness of the separator can be 3 μm to 30 μm.

[0075] The secondary battery of the present application further comprises a packaging bag for accommodating the positive electrode sheet, the separator, the negative electrode sheet, and the non-aqueous electrolyte, as well as other components known in the art in the secondary battery. The present application does not limit the above-mentioned other components. There is no particular limitation on the packaging bag in the present application, and it can be a packaging bag well-known in the art as long as the object of the present application can be achieved.

[0076] There is no particular limitation on the type of the secondary battery in the present application, and it may include any device that undergoes an electrochemical reaction. In the present application, the secondary battery may include, but is not limited to: lithium metal secondary batteries, lithium ion secondary batteries (lithium ion batteries), lithium polymer secondary batteries, or lithium ion polymer secondary batteries (lithium ion polymer batteries), etc.

[0077] The preparation process of the secondary battery of the present application is well-known to those skilled in the art, and there is no particular limitation in the present application. For example, it may include, but is not limited to, the following steps: stacking the positive electrode sheet, the separator, and the negative electrode sheet in sequence, and winding, folding, etc. as needed to obtain a wound electrode assembly, placing the electrode assembly into a packaging bag, injecting the non-aqueous electrolyte into the packaging bag and sealing it to obtain a secondary battery; or, stacking the positive electrode sheet, the separator, and the negative electrode sheet in sequence, and then fixing the four corners of the entire laminated structure with tape to obtain a laminated electrode assembly, placing the electrode assembly into a packaging bag, injecting the non-aqueous electrolyte into the packaging bag and sealing it to obtain a secondary battery. In addition, an overcurrent protection element, a guide plate, etc. may be placed in the packaging bag as needed to prevent the pressure inside the secondary battery from rising and overcharging / discharging.

[0078] The third aspect of the present application provides an electronic device, which comprises the secondary battery in any of the foregoing embodiments. Thus, the electronic device provided by the present application has good performance in use.

[0079] The type of the electronic device in this application is not particularly limited, and it can be any electronic device known in the prior art. In some embodiments of this application, the electronic device may include, but is not limited to, laptop computers, pen-input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, liquid crystal televisions, hand-held cleaners, portable CD players, minidiscs, transceivers, electronic notepads, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, motorized bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household storage batteries, and lithium-ion capacitors, etc.

[0080] Examples

[0081] Hereinafter, examples and comparative examples are given to more specifically illustrate the embodiments of this application. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0082] Testing methods and equipment:

[0083] Low-temperature discharge performance test:

[0084] Place the lithium-ion battery in a constant-temperature environment of 25°C and let it stand for 30 min to make the lithium-ion battery reach a constant temperature state of 25°C. Charge it at a constant current of 0.5C to 4.5V, charge it at a constant voltage of 4.5V until the current is 0.025C, discharge it at a constant current of 0.2C to 3.0V, and record the discharge capacity at 25°C as C2. Then charge it at a constant current of 0.5C to 4.5V, charge it at a constant voltage of 4.5V until the current is 0.025C, transfer the lithium-ion battery to a constant-temperature test chamber at -10°C, let it stand for 60 min to make the lithium-ion battery reach a constant temperature state of -10°C, and then discharge it at a constant current of 0.2C to 3.0V, and record the discharge capacity at -10°C as C3.

[0085] Low-temperature discharge capacity retention rate at -10°C = C3 / C2 × 100%.

[0086] High-temperature storage performance test:

[0087] Place the lithium-ion battery in a constant-temperature environment of 25°C and let it stand for 30 min to make the lithium-ion battery reach a constant temperature state of 25°C. Charge it at a constant current of 0.5C to 4.5V, charge it at a constant voltage of 4.5V until the current is 0.025C, and record the thickness of the lithium-ion battery at this time as the initial thickness H0. Transfer the lithium-ion battery to a constant-temperature oven at 60°C for storage for 30 days. During this period, test and record the thickness of the lithium-ion battery every 6 days. The test thickness recorded after 30 days is the storage thickness H1.

[0088] High-temperature storage thickness expansion rate = (H1 - H0) / H0 × 100%.

[0089] Example 1-1

[0090] <Preparation of positive electrode sheet>

[0091] Mix the positive active material lithium cobaltate, conductive agent Super P, and binder polyvinylidene fluoride in a mass ratio of 97.9:0.9:1.2, add N-methylpyrrolidone (NMP) as a solvent, and formulate into a slurry with a solid content of 75 wt%. After vacuum stirring evenly, obtain the positive electrode slurry. Coat the positive electrode slurry evenly on one surface of a positive electrode current collector aluminum foil with a thickness of 10 μm, and dry it at 120°C to obtain a positive electrode sheet with a single-sided coated positive electrode material layer. The coating weight of the positive electrode material layer is 267.8 mg / 1540 mm 2 . Then repeat the above steps on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided coated positive electrode material layer. After drying at 120°C, cold press it, and then cut the sheet and weld the tab to obtain a positive electrode sheet with a specification of 74 mm × 867 mm for use. Among them, the thickness of the single-sided positive electrode material layer is 42 μm.

[0092] <Preparation of negative electrode sheet>

[0093] Mix the negative active material artificial graphite, binder styrene-butadiene rubber, and conductive agent acetylene black in a mass ratio of 97.4:1.4:1.2, add deionized water as a solvent, and formulate into a slurry with a solid content of 45 wt%. After vacuum stirring evenly with a vacuum mixer, obtain the negative electrode slurry. Coat the negative electrode slurry evenly on one surface of a negative electrode current collector copper foil with a thickness of 6 μm, and dry it at 120°C to obtain a negative electrode sheet with a single-sided coated negative electrode material layer. The coating weight of the negative electrode material layer is 142 mg / 1540 mm 2 . Then repeat the above steps on the other surface of the copper foil to obtain a negative electrode sheet with a double-sided coated negative electrode material layer. After drying at 120°C, cold press it, and then cut the sheet and weld the tab to obtain a negative electrode sheet with a specification of 78 mm × 875 mm for use. Among them, the thickness of the single-sided negative electrode material layer is 54.5 μm.

[0094] <Preparation of non-aqueous electrolyte>

[0095] In an argon atmosphere glove box with a water content of less than 10 ppm, mix diethyl carbonate and ethylene carbonate in a mass ratio of 1:1 to obtain a basic solvent, and then add fluoro sulfonamide type I-1 and sulfonamide lithium salt type II-1 to the basic solvent and stir evenly to obtain a non-aqueous electrolyte. Among them, based on the mass of the non-aqueous electrolyte, the mass percentage content W of fluoro sulfonamide type I-1 Iis 30%, and the mass percentage content W of the lithium salt of sulfonamide of formula II-1 II is 20%, and the balance is the base solvent.

[0096] <Preparation of separator>

[0097] A polyethylene (PE) film with a thickness of 7 μm is used.

[0098] <Preparation of lithium ion battery>

[0099] The positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in sequence, with the separator placed between the positive electrode sheet and the negative electrode sheet to play an isolation role, and then wound to obtain an electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag, dehydrated at 80 °C, and the non-aqueous electrolyte prepared above is injected. After vacuum packaging, standing, forming, degassing, trimming and other processes, a lithium ion battery is obtained. Among them, the upper limit voltage of forming is 4.15 V, the forming temperature is 70 °C, and the forming standing time is 2 h.

[0100] Examples 1-2 to Examples 1-12

[0101] Except for adjusting the relevant preparation parameters according to Table 1, the rest are the same as in Example 1-1. Among them, when the mass percentage content of at least one of the fluorosulfonamide and / or the lithium salt of sulfonamide changes, the mass percentage content of the base solvent changes accordingly, and the mass ratio of diethyl carbonate to ethylene carbonate in the base solvent remains unchanged.

[0102] Example 1-13

[0103] Except for preparing the non-aqueous electrolyte according to the following method, the rest are the same as in Example 1-1.

[0104] <Preparation of non-aqueous electrolyte>

[0105] In a glove box under an argon atmosphere with a water content of less than 10 ppm, diethyl carbonate and ethylene carbonate are mixed in a mass ratio of 1:1 to obtain a base solvent, and then fluorosulfonamide of formula I-1, lithium salt of sulfonamide of formula II-1 and other lithium salt lithium hexafluorophosphate (LiPF6) are added to the base solvent and stirred evenly to obtain a non-aqueous electrolyte. Among them, based on the mass of the non-aqueous electrolyte, the mass percentage content W of fluorosulfonamide of formula I-1 I is 50%, and the mass percentage content W of the lithium salt of sulfonamide of formula II-1 II is 10%, the mass percentage content of other lithium salts is 10%, and the balance is the base solvent.

[0106] Examples 1-14 to Examples 1-16

[0107] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as in Example 1-1. Among them, when the mass percentage content of fluorosulfonamide changes, the mass percentage content of lithium sulfonamide remains unchanged, and the mass percentage content of the base solvent changes accordingly, while the mass ratio of diethyl carbonate to ethylene carbonate in the base solvent remains unchanged.

[0108] Examples 1-17 to 1-19

[0109] Except for adding another lithium salt, lithium hexafluorophosphate (LiPF6), during the preparation of the non-aqueous electrolyte and adjusting the relevant preparation parameters according to Table 1, the rest is the same as in Example 1-1. Among them, when the mass percentage content of lithium sulfonamide and / or another lithium salt changes, the mass percentage content of fluorosulfonamide remains unchanged, and the mass percentage content of the base solvent changes accordingly, while the mass ratio of diethyl carbonate to ethylene carbonate in the base solvent remains unchanged.

[0110] Examples 1-20 to 1-21

[0111] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as in Example 1-1. Among them, when the mass percentage content of lithium sulfonamide changes, the mass percentage content of fluorosulfonamide remains unchanged, and the mass percentage content of the base solvent changes accordingly, while the mass ratio of diethyl carbonate to ethylene carbonate in the base solvent remains unchanged.

[0112] Examples 2-1 to 2-14

[0113] Except for adding the first component and / or the second component during the preparation of the non-aqueous electrolyte and adjusting the relevant preparation parameters according to Table 2, the rest is the same as in Example 1-1. Among them, when the mass percentage content of at least one of the first component and / or the second component changes, the mass percentage content of the base solvent changes accordingly, while the mass ratio of diethyl carbonate to ethylene carbonate remains unchanged.

[0114] Comparative Example 1

[0115] Except for preparing the non-aqueous electrolyte according to the following method, the rest is the same as in Example 1-1.

[0116] <Preparation of Non-aqueous Electrolyte>

[0117] In a glove box under an argon atmosphere with a water content of less than 10 ppm, diethyl carbonate and ethylene carbonate were mixed in a mass ratio of 1:1 to obtain a base solvent, and then another lithium salt, lithium hexafluorophosphate (LiPF6), was added to the base solvent and stirred evenly to obtain a non-aqueous electrolyte. Among them, based on the mass of the non-aqueous electrolyte, the mass percentage content of the other lithium salt was 20%, and the balance was the base solvent.

[0118] Comparative Example 2

[0119] Except for preparing the non-aqueous electrolyte according to the following method, the rest is the same as in Example 1-1.

[0120] <Preparation of non-aqueous electrolyte>

[0121] In an argon atmosphere glove box with a water content of less than 10 ppm, diethyl carbonate and ethylene carbonate were mixed in a mass ratio of 1:1 to obtain a base solvent, and then lithium fluorosulfonamide formula I-1 and other lithium salts lithium hexafluorophosphate (LiPF6) were added to the base solvent and stirred evenly to obtain a non-aqueous electrolyte. Among them, based on the mass of the non-aqueous electrolyte, the mass percentage content W of lithium fluorosulfonamide formula I-1 I is 30%, the mass percentage content of other lithium salts is 20%, and the balance is the base solvent.

[0122] Comparative Example 3

[0123] Except for preparing the non-aqueous electrolyte according to the following method, the rest is the same as in Example 1-1.

[0124] <Preparation of non-aqueous electrolyte>

[0125] In an argon atmosphere glove box with a water content of less than 10 ppm, diethyl carbonate and ethylene carbonate were mixed in a mass ratio of 1:1 to obtain a base solvent, and then lithium sulfonamide salt formula II-1 was added to the base solvent and stirred evenly to obtain a non-aqueous electrolyte. Among them, based on the mass of the non-aqueous electrolyte, the mass percentage content W of lithium sulfonamide salt formula II-1 II is 20%, and the balance is the base solvent.

[0126] Table 1

[0127]

[0128]

[0129] Note: " / " in Table 1 indicates the non-existence of the corresponding preparation parameter or substance

[0130] As can be seen from Examples 1-1 to 1-21 and Comparative Examples 1 to 3, the non-aqueous electrolyte of the embodiments of the present application contains fluorosulfonamide and lithium sulfonamide salt. With their synergistic effect, the lithium-ion battery has a relatively high low-temperature discharge capacity retention rate and a relatively small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery of the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance. In Comparative Example 1, the non-aqueous electrolyte does not include fluorosulfonamide and lithium sulfonamide salt; in Comparative Example 2, the electrolyte does not include lithium sulfonamide salt; in Comparative Example 3, the non-aqueous electrolyte does not include fluorosulfonamide. At this time, the lithium-ion batteries in Comparative Examples 1 to 3 have a relatively low low-temperature discharge capacity retention rate and / or a relatively large high-temperature storage thickness expansion rate, indicating that the lithium-ion batteries in Comparative Examples 1 to 3 have poor low-temperature discharge performance and / or high-temperature storage performance.

[0131] The type of fluorosulfonamide affects the low-temperature discharge performance and high-temperature storage performance of the lithium-ion battery. As can be seen from Examples 1-1 to 1-5, when the type of fluorosulfonamide is adjusted within the scope of the present application, the lithium-ion battery can have a relatively high low-temperature discharge capacity retention rate and a relatively small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance.

[0132] The type of lithium sulfonamide salt affects the discharge performance and high-temperature storage performance of the lithium-ion battery. As can be seen from Examples 1-1, 1-6 to 1-8, when the type of lithium sulfonamide salt is adjusted within the scope of the present application, the lithium-ion battery can have a relatively high low-temperature discharge capacity retention rate and a relatively small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance.

[0133] The mass percentage content of fluorosulfonamide affects the discharge performance and high-temperature storage performance of the lithium-ion battery. As can be seen from Examples 1-1, 1-9 to 1-16, when the mass percentage content W I of fluorosulfonamide is adjusted within the scope of the present application, the lithium-ion battery can have a relatively high low-temperature discharge capacity retention rate and a relatively small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance.

[0134] The mass percentage content of lithium sulfonamide salt affects the discharge performance and high-temperature storage performance of the lithium-ion battery. As can be seen from Examples 1-1, 1-17 to 1-21, when the mass percentage content W IIWhen within the scope of the present application, it is possible to enable a lithium-ion battery to have a high low-temperature discharge capacity retention rate and at the same time have a small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance.

[0135] W I +W II The value of will affect the discharge performance and high-temperature storage performance of the lithium-ion battery. It can be seen from Examples 1-1, 1-9 to 1-16 that when the value of W I +W II is within the scope of the present application, it is possible to enable the lithium-ion battery to have a high low-temperature discharge capacity retention rate and at the same time have a small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance.

[0136] Table 2

[0137]

[0138]

[0139] Note: " / " in Table 2 indicates that there is no corresponding preparation parameter or substance

[0140] The type and mass percentage content of the first component will affect the discharge performance and high-temperature storage performance of the lithium-ion battery. It can be seen from Examples 2-1 to 2-8 that when the type and mass percentage content of the first component are regulated within the scope of the present application, it is possible to enable the lithium-ion battery to have a high low-temperature discharge capacity retention rate and at the same time have a small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance.

[0141] The relationship between the mass percentage content of the first component and the mass percentage contents of other components W III / (100% - (W I +W II )) will affect the discharge performance and high-temperature storage performance of the lithium-ion battery. It can be seen from Examples 2-1 to 2-7 that when the value of W III / (100% - (W I +W II )) is within the scope of the present application, it is possible to enable the lithium-ion battery to have a high low-temperature discharge capacity retention rate and at the same time have a small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of the present application has good low-temperature discharge performance and high-temperature storage performance.

[0142] The type and mass percentage content of the second component will affect the discharge performance and high-temperature storage performance of the lithium-ion battery. It can be seen from Examples 2-9 to 2-13 that when the type and mass percentage content of the second component are adjusted within the scope of this application, the lithium-ion battery can have a high low-temperature discharge capacity retention rate and a small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of this application has good low-temperature discharge performance and high-temperature storage performance.

[0143] The composition of the non-aqueous electrolyte will affect the discharge performance and high-temperature storage performance of the lithium-ion battery. It can be seen from Examples 1-1, 2-1 to 2-14 that when the electrolyte within the composition range of this application is selected, the lithium-ion battery can have a high low-temperature discharge capacity retention rate and a small high-temperature storage thickness expansion rate, indicating that the lithium-ion battery provided by the embodiments of this application has good low-temperature discharge performance and high-temperature storage performance.

[0144] The above are only the preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included within the scope of protection of this application.

Claims

1. A non-aqueous electrolyte comprising a fluorosulfonamide of formula I and a lithium sulfonamide of formula II: in, R1 is selected from a fluorine atom or a C1 to C5 alkyl group at least partially substituted by fluorine; R2 and R3 are each independently selected from a C1 to C5 alkyl group, and R2 and R3 can be connected to form a ring by a single bond; R4 and R5 are each independently selected from a fluorine atom, a C1 to C5 alkyl group, a C1 to C5 alkyl group at least partially substituted by fluorine, or a C1 to C5 alkoxy group at least partially substituted by fluorine.

2. The nonaqueous electrolyte according to claim 1, wherein The fluorosulfonamide represented by formula I comprises at least one of the following compounds:

3. The nonaqueous electrolyte according to claim 1, wherein The sulfonamide lithium salt shown in Formula II includes at least one of the following compounds:

4. The nonaqueous electrolyte according to claim 1, wherein R1 is selected from a fluorine atom or a trifluoromethyl group; R2 and R3 are each independently selected from a methyl group or an ethyl group; R2 and R3 are connected by a single bond to form a five-membered ring or a six-membered ring.

5. The non-aqueous electrolyte according to claim 1, wherein R4 and R5 are each independently selected from a fluorine atom, a trifluoromethyl group, a methyl group or a trifluoromethoxy group.

6. The nonaqueous electrolyte according to any one of claims 1 to 5, wherein Based on the mass of the non-aqueous electrolyte, the mass percentage of the fluorosulfonamide is W I , 5% ≤ W I ≤60%; preferably, 10%≤W I ≤50%.

7. The nonaqueous electrolyte according to any one of claims 1 to 5, wherein Based on the mass of the non-aqueous electrolyte, the mass percentage of the sulfonamide lithium salt is W II , 10% ≤ W II ≤40%; preferably, 15%≤W II ≤30%.

8. The nonaqueous electrolyte according to any one of claims 1 to 5, wherein Based on the mass of the non-aqueous electrolyte, the mass percentage of the fluorosulfonamide is W I The mass percentage of the sulfonamide lithium salt is W II , 30% ≤ W I +W II ≤60%.

9. The nonaqueous electrolyte according to any one of claims 1 to 5, wherein The non-aqueous electrolyte further includes a first component, the first component including at least one of fluoroethylene carbonate, difluoroethylene carbonate, vinylene carbonate or vinyl ethylene carbonate, and the mass percentage of the first component is W based on the mass of the non-aqueous electrolyte. III , 0.5% ≤ W III ≤15%; preferably, 1%≤W III ≤10%.

10. The non-aqueous electrolyte according to claim 9, wherein Based on the mass of the non-aqueous electrolyte, the mass percentage of the fluorosulfonamide is W I The mass percentage of the sulfonamide lithium salt is W II , 0.1≤W III / (100%-(W I +W II ))≤1.

11. The nonaqueous electrolyte according to any one of claims 1 to 5, wherein The non-aqueous electrolyte further includes a second component, which includes at least one of succinonitrile, glutaronitrile, methylglutaronitrile, adiponitrile or 1,3,6-hexanetrinitrile.

12. The nonaqueous electrolyte according to claim 11, wherein Based on the mass of the non-aqueous electrolyte, the mass percentage of the second component is 0.5% to 5%. 13 . A secondary battery comprising a positive electrode sheet, a negative electrode sheet, a separator and the nonaqueous electrolyte according to claim 1 . 14 . An electronic device comprising the secondary battery according to claim 13 .

Images