Non-aqueous electrolyte solution and secondary battery

Abstract

The invention provides a non-aqueous electrolyte and a secondary battery. The non-aqueous electrolyte comprises an electrolyte salt, a non-aqueous organic solvent and an additive. The additive comprises a disulfonyl compound as shown in a structural formula I in the specification. Wherein the structure of R1 is shown as a formula I, a formula II, a formula III or a formula IV, R2 is halogen, and n is an integer of 1-4. The non-aqueous electrolyte contains a disulfonyl compound, can improve the dynamic performance and the cycle performance of the battery no matter in a fast charging system or a low-temperature system, and is suitable for a lithium ion battery and a sodium ion battery at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy batteries, and in particular relates to a non-aqueous electrolyte and a secondary battery. Background Art

[0002] Lithium-ion batteries have significant technical advantages over traditional batteries such as lead-acid batteries, nickel-cadmium batteries and nickel-metal hydride batteries. Its energy density is much higher than other types of batteries, which means that at the same weight, lithium-ion batteries can provide longer battery life and stronger performance support. This feature makes lithium-ion batteries particularly suitable for fields that require lightweight and high battery life, such as laptops, smart wearable devices and drones. In addition, lithium-ion batteries have long cycle life, low self-discharge rate, support for fast charging and no memory effect, which makes lithium-ion batteries the preferred choice in many fields. As society's requirements for environmental protection and energy conservation and consumption reduction increase, the environmental protection and energy-saving advantages of lithium-ion batteries are becoming more and more prominent. Lithium-ion batteries do not contain heavy metals such as mercury and lead, and have less impact on the environment. At the same time, lithium-ion batteries are suitable for clean energy storage systems, such as solar and wind power, which helps reduce dependence on fossil fuels and achieve carbon neutrality goals. Furthermore, the application fields of lithium-ion batteries are wide and expanding. From the early consumer electronics field to the new energy vehicle industry in recent years, lithium-ion batteries have played a vital role. With the rapid development of the new energy vehicle market, power batteries have become one of the main application areas of lithium-ion batteries. In addition, lithium-ion batteries are also gradually being used in emerging markets such as energy storage systems, power tools, and industrial electronic equipment.

[0003] However, as the global demand for clean energy continues to rise, the importance of energy storage technology has become increasingly prominent. As an emerging energy storage technology, sodium-ion batteries have gradually come into people's view with their unique advantages. The working principle of sodium-ion batteries is similar to that of lithium-ion batteries, but sodium ions are used instead of lithium ions. Compared with lithium, sodium is more abundant in the earth's crust and cheaper, which gives sodium-ion batteries significant advantages in raw material acquisition and cost control. In addition, sodium-ion batteries also have the characteristics of high safety, good thermal stability, environmental friendliness, superior low-temperature performance and long cycle life. These advantages make sodium-ion batteries show broad application prospects in many fields such as new energy vehicles, home energy storage systems, industrial and commercial energy storage, two-wheeled and three-wheeled electric vehicles, backup power supplies for communication base stations, and low-temperature environment applications.

[0004] However, both lithium-ion batteries and sodium-ion batteries face some challenges. For example, in the fields of electric vehicles and drones, higher and higher requirements are placed on the fast charging performance, cycle performance and performance under extreme temperatures of lithium-ion batteries and sodium-ion batteries. Traditional electrolyte systems and electrolyte additives such as vinylene carbonate (VC) and diethyl sulfate (DTD) can no longer meet the current requirements of lithium-ion batteries and sodium-ion batteries for fast charging and low temperature. Summary of the invention

[0005] Based on the above problems, the purpose of the present invention is to provide a non-aqueous electrolyte and a secondary battery, wherein the non-aqueous electrolyte contains a disulfonyl compound, which can improve the battery's kinetic performance and cycle performance regardless of fast charging or low temperature systems, and is suitable for both lithium-ion batteries and sodium-ion batteries.

[0006] To achieve the above object, the present invention provides a non-aqueous electrolyte on one hand. The non-aqueous electrolyte comprises an electrolyte salt, a non-aqueous organic solvent and an additive. The additive comprises a disulfonyl compound as shown in structural formula I, wherein the structure of R1 is as shown in formula I, formula II, formula III or formula IV, R2 is a halogen, and n is an integer of 1 to 4.

[0007]

[0008]

[0009] In the electrolyte of the present invention, the additive of the non-aqueous electrolyte includes a disulfonyl compound, which has a disulfonyl group (see structural formula I) and a cyclic sulfate (see formula three and formula four) or a cyclic phosphate group (see formula one and formula two). This type of disulfonyl compound with multiple functional groups is used in batteries of different battery systems, and can effectively form a SEI rich in sulfur or phosphorus on the positive and negative electrodes. In addition, the disulfonyl compound is different from conventional cyclic phosphate additives and cyclic sulfate additives. Since there is a short-chain disulfonyl group in the middle to link two cyclic phosphates or cyclic sulfates, when the cyclic phosphate or cyclic sulfate is oxidized or reduced to form a film, Li can be inserted in the middle. x SO y components, so as to form a phosphate polymer film-Li x SO y -Phosphate polymer membrane type or sulfate polymer membrane-Li x SO y -Sulfate polymer film type SEI or CEI. This type of SEI or CEI is more resilient and has extremely high ionic conductivity, so it helps to reduce the DCIR of the battery, thereby improving the kinetic performance (such as rate performance, low temperature performance) and cycle performance of the secondary battery.

[0010] As a technical solution of the present invention, the disulfonyl compound is selected from at least one of Compound 1 to Compound 6.

[0011]

[0012]

[0013] As a technical solution of the present invention, the mass percentage of the disulfonyl compound in the non-aqueous electrolyte is 0.1-3.0%.

[0014] As a technical solution of the present invention, the non-aqueous organic solvent is selected from at least one of ethylene carbonate, fluorinated ethylene carbonate, ethyl difluoroacetate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, butyl acetate, γ-butyrolactone, propyl propionate, ethyl propionate, ethyl acetate and ethyl butyrate.

[0015] As a technical solution of the present invention, it further includes an auxiliary agent, the mass percentage of the auxiliary agent in the non-aqueous electrolyte is 0.5-10.5%, and the auxiliary agent is selected from at least one of vinylene carbonate, difluoro vinylene carbonate, 1,3-propane sultone, ethylene sulfate, tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite.

[0016] The second aspect of the present invention provides a secondary battery, including a positive electrode material, a negative electrode material and the aforementioned non-aqueous electrolyte.

[0017] As a technical solution of the present invention, the positive electrode material is a lithium ion positive electrode material, and the electrolyte salt is a lithium salt.

[0018] As a technical solution of the present invention, the chemical formula of the lithium ion positive electrode material is LiNi x Co y Mn z M 1-x-y-z O2 or LiNi x Co y Al z M 1-x-y-z O2, where M is at least one of Mg, Cu, Zn, Sn, B, Ga, Cr, Sr, V and Ti, 0.5≤x<1.0, 0<y<1.0, 0<z<1.0, 0.9<x + y + z≤1.0, the negative electrode material includes at least one of artificial graphite, natural graphite, silicon oxide composite material and silicon carbon composite material, and the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoroborate, lithium tetrafluoro(oxalato)phosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium bifluorosulfonylimide and lithium difluorobis(fluoromalonate)borate.

[0019] As a technical solution of the present invention, the positive electrode material is a sodium-ion positive electrode material, and the electrolyte salt is a sodium salt.

[0020] As a technical solution of the present invention, the chemical formula of the sodium-ion positive electrode material is Na x M (1-y-z) Fe y Mn z O2, where M is at least one of Co, Ni, Cu, Mg, Zn, Al, Sn, Ga, Cr, Sr, V, and Ti, 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z ≤ 1. The negative electrode material includes at least one of a carbon-based negative electrode material, a titanium-based oxide negative electrode material, and an alloy-based negative electrode material. The sodium salt is selected from at least one of sodium hexafluorophosphate, sodium difluorophosphate, sodium bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium difluorobis(oxalato)phosphate, sodium tetrafluoroborate, sodium bis(trifluoromethylsulfonyl)imide, and sodium bis(fluorosulfonyl)imide. Detailed implementation manners

[0021] The secondary battery of the present invention has excellent rate performance, low-temperature performance, and cycle performance. When cycled 1000 times under a high-voltage system of 4.35V, the capacity retention rate can still reach more than 90%. When cycled 500 times under a system of 4.35V and 4C, the capacity retention rate can still reach more than 80%. The low-temperature performance at -20°C is also excellent.

[0022] The secondary battery includes a positive electrode material, a negative electrode material, and a non-aqueous electrolyte. It can be a lithium-ion battery or a sodium-ion battery. If it is a lithium-ion battery, the positive electrode material is a lithium-ion positive electrode material. Further, the chemical formula of the lithium-ion positive electrode material can be LiNi x Co y Mn z M 1-x-y-z O2 or LiNi x Co y Al z M 1-x-y-z O2, where M is at least one of Mg, Cu, Zn, Sn, B, Ga, Cr, Sr, V, and Ti, 0.5 ≤ x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0.9 < x + y + z ≤ 1.0. The negative electrode material that can be matched includes at least one of artificial graphite, natural graphite, silicon-oxygen composite material, and silicon-carbon composite material. If it is a sodium-ion battery, the positive electrode material is a sodium-ion positive electrode material. Further, the chemical formula of the sodium-ion positive electrode material can be Na x M (1-y-z) Fe y Mn zO2, wherein M is at least one of Co, Ni, Cu, Mg, Zn, Al, Sn, Ga, Cr, Sr, V, and Ti, 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, and y + z ≤ 1. The paired anode material may include at least one of a carbon-based anode material, a titanium-based oxide anode material, and an alloy-based anode material. The carbon-based material may include at least one of artificial graphite, natural graphite, hard carbon, soft carbon, graphene, and mesophase carbon microspheres. The titanium-based oxide anode material may include at least one of sodium titanate, titanium niobium oxide, and TiO2. The alloy-based anode material may include at least one of sodium-silicon alloy, lithium-sodium alloy, sodium-potassium alloy, sodium-aluminum alloy, sodium-tin alloy, and sodium-indium alloy.

[0023] The non-aqueous electrolyte of the present invention is applicable to lithium-ion batteries and sodium-ion batteries. The non-aqueous electrolyte includes an electrolyte salt, a non-aqueous organic solvent, and an additive. Further, it may also include an auxiliary agent.

[0024] The mass ratio of the non-aqueous organic solvent in the electrolyte is 60% - 90%. Preferably, the mass ratio of the non-aqueous organic solvent is 80% - 90%. By way of example, the mass ratio of the non-aqueous organic solvent is 60%, 63%, 66%, 67%, 69%, 70%, 71%, 72%, 73%, 74%, 77%, 80%, 82%, 84%, 86%, 88%, 90%. The content of the non-aqueous organic solvent is not limited to the listed values, and other unlisted values within this range are equally applicable. The non-aqueous organic solvent includes at least one of carbonate compounds, carboxylate compounds, and ether compounds. Further, the carbonate compounds include, but are not limited to, at least one of ethylene carbonate (EC), fluoroethylene carbonate (FEC), ethyl difluoroacetate (DFEA), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propylene carbonate (PC), butyl acetate (BA), γ-butyrolactone (GBL), propyl propionate (PP), ethyl propionate (EP), ethyl acetate (EA), and ethyl butyrate (EB).

[0025] The mass proportion of electrolyte salt in the electrolyte is 10-25%. Preferably, the mass proportion of electrolyte salt is 10-18%. As an example, the mass proportion of electrolyte salt is 10%, 12%, 14%, 15%, 16%, 18%, 20%, 23%, 25%, and the content of electrolyte salt is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. If it is a lithium ion battery, the electrolyte salt is a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bis oxalate borate, lithium difluoro oxalate borate, lithium difluorobis oxalate phosphate, lithium tetrafluoroborate, lithium tetrafluoro oxalate phosphate, bis trifluoromethyl sulfonyl imide lithium, bis fluorosulfonyl imide lithium and 2-fluoromalonate difluoroborate lithium. If it is a sodium ion battery, the electrolyte salt is a sodium salt, and the sodium salt may include at least one of sodium hexafluorophosphate, sodium difluorophosphate, sodium bisoxalatoborate, sodium difluorooxalatoborate, sodium difluorobisoxalatophosphate, sodium tetrafluoroborate, sodium bistrifluoromethylsulfonyl imide and sodium bisfluorosulfonyl imide.

[0026] The additive includes a disulfonyl compound as shown in structural formula I, and the mass proportion of the disulfonyl compound in the electrolyte is 0.1-3.0%. Preferably, the mass proportion of the disulfonyl compound is 0.5-2.0%. As an example, the mass proportion of the disulfonyl compound can be, but is not limited to, 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 1.3%, 1.5%, 1.7%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, and 3.0%.

[0027] In the disulfonyl compound shown in structural formula I, the structure of R1 is as shown in formula 1, formula 2, formula 3 or formula 4, R2 is a halogen, and n is an integer of 1 to 4.

[0028]

[0029] Furthermore, R2 is fluorine, n is an integer of 2 to 4, and further, the disulfonyl compound is at least one selected from Compound 1 to Compound 6.

[0030]

[0031]

[0032] The synthesis methods of compounds 1 to 4 are shown in reaction formulas 1 and 2. The raw material disulfonyl chloride in reaction formulas 1 and 2 can refer to the synthesis process of 1,4-butane disulfonyl chloride in patent CN118388378B, and the disulfonyl compounds with different carbon chain lengths only need to replace the raw material 1,4-dibromobutane with dibromoalkanes with different carbon chain lengths, such as 1,2-dibromoethane, 1,3-dibromopropane, etc. The synthesis methods of compounds 5 and 6 can refer to the synthesis method of compound 4 in reaction formula 2.

[0033]

[0034]

[0035] The non-aqueous electrolyte of the present invention may further include an auxiliary agent. The mass proportion of the auxiliary agent in the non-aqueous electrolyte is 0.5~10.5%. As an example, it can be but not limited to 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 10.5%. The auxiliary agent is selected from at least one of vinylene carbonate (VC), bisfluoroethylene carbonate (DEPC), 1,3-propane sultone (PS), vinyl sulfate (DTD), tris(trimethylsilane) phosphate (TMSP) and tris(trimethylsilane) phosphite (TMSPi). Preferably, the auxiliary agent is vinylene carbonate or bisfluoroethylene carbonate, and its mass proportion in the non-aqueous electrolyte is preferably 0.2~3.0%.

[0036] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0037] If no specific conditions are specified in the examples and comparative examples, the experiments may be carried out under conventional conditions or conditions recommended by the manufacturer. If no manufacturer is specified for the reagents or instruments used, they are all conventional products available on the market.

[0038] Example 1 In a glove box filled with nitrogen (O2 <1ppm, H2O <2ppm), ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate were mixed in a volume ratio of 3:4:3 to obtain 85.5g of a non-aqueous organic solvent, and 0.5g of the compound was added to obtain a mixed solution. The mixed solution was sealed and packaged and placed in a quick freezer (-4°C) for 2h, then taken out and slowly added to the mixed solution in a glove box filled with nitrogen (O2 <1ppm, H2O <2ppm) 14.0g of lithium hexafluorophosphate was added to the mixed solution, and the electrolyte was obtained after mixing evenly.

[0039] The electrolytes of Examples 2 to 14 were prepared with reference to Example 1, and the differences can be referred to Table 1. The electrolytes of Examples 15 to 20 were prepared by replacing the lithium salt in Example 1 with sodium salt, and the differences can be referred to Table 1. The electrolytes of Comparative Examples 1 to 7 were prepared with reference to Example 1 and Example 15, and the differences can be referred to Table 1.

[0040] Among them, the lithium ion batteries corresponding to Examples 1 to 14 and Comparative Examples 1 to 4 are LiNi with a maximum charging voltage of 4.35V. 0.8 Co 0.1 Mn 0.1 O2 is the positive electrode material, and artificial graphite is the negative electrode material. The sodium ion batteries corresponding to Examples 15 to 20 and Comparative Examples 5 to 7 are layered NaNi with a maximum charging voltage of 4.2V. 1 / 3 Fe 1 / 3 Mn 1 / 3 O 22 As the positive electrode material, hard carbon is the negative electrode material. Lithium-ion batteries and sodium-ion batteries can be synthesized by referring to conventional battery preparation processes.

[0041] Table 1 Electrolyte formulations for batteries corresponding to Examples 1 to 20 and Comparative Examples 1 to 7

[0042]

[0043]

[0044] The structural formula of compound VII in Comparative Examples 2-4 and Comparative Examples 6-7 is shown below.

[0045]

[0046] The batteries of Examples 1 to 20 and Comparative Examples 1 to 7 were tested for room temperature cycle performance, high rate cycle performance and low temperature discharge performance, respectively. The test conditions are as follows. The test results are shown in Table 2.

[0047] (1) Room-temperature cycle performance test of lithium-ion batteries of Examples 1 to 14 and Comparative Examples 1 to 4 Place the lithium-ion battery in an environment of 25°C, charge it to 4.35V at a constant current of 1C, then charge it at a constant voltage until the current drops to 0.05C, and then discharge it to 3.0V at a constant current of 1C, repeat this cycle, and record the discharge capacity of the first cycle and the discharge capacity of the last cycle. Calculate the capacity retention rate of high temperature cycles according to the following formula.

[0048] Capacity retention rate = discharge capacity of the last cycle / discharge capacity of the first cycle × 100% (2) High-rate cycle performance test of lithium-ion batteries of Examples 1 to 14 and Comparative Examples 1 to 4 Place the lithium-ion battery in a 25°C environment, charge it to 4.35V at a constant current of 4C, then charge it at a constant voltage until the current drops to 0.05C, then discharge it to 3.0V at a constant current of 1C, repeat this cycle, and record the discharge capacity of the first cycle and the discharge capacity of the last cycle. Calculate the capacity retention rate of high temperature cycles according to the following formula.

[0049] Capacity retention rate = discharge capacity of the last cycle / discharge capacity of the first cycle × 100% (3) Low-temperature discharge test of lithium-ion batteries of Examples 1 to 14 and Comparative Examples 1 to 4 Place the lithium-ion battery in an environment of 25°C, charge it to 4.35V at a constant current of 1C, then charge it at a constant voltage until the current drops to 0.05C, then discharge it to 3.0V at a constant current of 1C, and record the discharge capacity at this time as C0. Then charge it to 4.35V at a constant current of 1C, then charge it at a constant voltage until the current drops to 0.05C, then place the battery in an environment of -20°C for more than 4 hours, and discharge it to 3.0V at a constant current of 0.5C at -20°C, and record the discharge capacity at this time as C1.

[0050] Capacity retention rate = C1 / C0×100% In addition, the room temperature cycle, high rate cycle and low temperature discharge tests of the sodium ion batteries of Examples 15 to 20 and Comparative Examples 5 to 7 are the same as the lithium ion battery test conditions except that the maximum charging voltage is 4.2V.

[0051] Table 2 Battery performance test results of various embodiments and comparative examples

[0052] It can be seen from the results in Table 2 that the room temperature cycle performance, high rate cycle performance and low temperature discharge performance of Examples 1 to 20 are better than those of Comparative Examples 1 to 7. This is because the additives of the non-aqueous electrolytes of Examples 1 to 20 include disulfonyl compounds, which have both disulfonyl groups and cyclic sulfate or cyclic phosphate groups. When this type of disulfonyl compound with multiple functional groups is used in lithium-ion batteries or sodium-ion batteries, it can effectively form a SEI rich in sulfur or phosphorus on the positive and negative electrodes. In addition, disulfonyl compounds are different from conventional cyclic phosphate additives and cyclic sulfate additives, because there is a short chain of disulfonyl groups in the middle to link two cyclic phosphates or cyclic sulfates. When the cyclic phosphate or cyclic sulfate is oxidized or reduced to form a film, Li can be inserted in the middle. x SO y components, so as to form a phosphate polymer film-Li x SO y -Phosphate polymer membrane type or sulfate polymer membrane-Li x SO y -Sulfate polymer film type SEI or CEI. This type of SEI or CEI is more resilient and has extremely high ionic conductivity, so it helps to reduce the DCIR of the battery, thereby improving the kinetic performance (such as rate performance, low temperature performance) and cycle performance of the secondary battery.

[0053] By comparing Examples 1 to 6 with Comparative Example 2, and Examples 15 to 16 with Comparative Example 6, it can be seen that although Compound 7 is also a disulfonyl compound, the two ends of the disulfonate are ethylene carbonate compounds. Carbonate compounds or alkane compounds are easily oxidized at the positive electrode or reduced at the negative electrode to form an organic component SEI. The organic component SEI usually has a large internal resistance and will cover the Li generated by the disulfonate in the middle. x S y O z The components will not form a phosphate polymer film of the disulfonyl compound of the present invention -Li x S y O z -Phosphate polymer membrane type or sulfate polymer membrane-Li x S y O z -Sulfate polymer membrane structure, which inhibits the effect of disulfonate itself, so the improvement of battery performance is not obvious.

[0054] Comparison of Examples 1 to 6 shows that when the disulfonyl compound is compound 1, the performance is better. This is because compound 1 can not only insert Li x SO y components, so as to form a phosphate polymer film-Li x SO y -phosphate polymer membrane, and because of the unique phosphite structure with strong reducing property, it can react preferentially with the oxygen free radicals released by the positive electrode, inhibiting the oxidation of the electrolyte by the oxygen free radicals released by the positive electrode.

[0055] Comparing Examples 9 to 14 with Examples 18 to 20, it can be seen that adding carbonate additives to the disulfonyl compounds helps to improve the performance of the battery. This is because the phosphate polymer film-Li x SO y -Phosphate polymer membrane type or sulfate polymer membrane-Li x SO y -Although the SEI or CEI of sulfate polymer film type has extremely high conductivity and low impedance, it still requires a certain amount of carbonate additives to form the film to enhance the toughness of the SEI film, so that even when the negative electrode expands due to lithium insertion, the SEI film is less likely to rupture, and thus has better cycle performance.

[0056] Combining Comparative Examples 3-4 and Comparative Example 7, it can be seen that even if sulfate or phosphate additives are added to Compound VII, the battery performance is still poor, indicating that even if sulfate or phosphate additives are added, it is impossible to overcome the negative impact of the large internal resistance SEI formed by carbonate compounds in the disulfonyl compounds with ethylene carbonate compounds at both ends.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A non-aqueous electrolyte comprising an electrolyte salt, a non-aqueous organic solvent and an additive, wherein the additive comprises a disulfonyl compound as shown in structural formula I, wherein: The structure of R1 is shown in Formula 1, Formula 2, Formula 3 or Formula 4, R2 is a halogen, and n is an integer of 1 to 4. 。 2. The non-aqueous electrolyte according to claim 1, characterized in that The disulfonyl compound is selected from at least one of Compounds 1 to 6, 。 3. The non-aqueous electrolyte according to claim 1, characterized in that The mass proportion of the disulfonyl compound in the non-aqueous electrolyte is 0.1-3.0%.

4. The non-aqueous electrolyte according to claim 1, characterized in that The non-aqueous organic solvent is selected from at least one of ethylene carbonate, fluoroethylene carbonate, ethyl difluoroacetate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, butyl acetate, γ-butyrolactone, propyl propionate, ethyl propionate, ethyl acetate and ethyl butyrate.

5. The non-aqueous electrolyte according to claim 1, characterized in that The invention also includes an auxiliary agent, the mass proportion of the auxiliary agent in the non-aqueous electrolyte is 0.5-10.5%, and the auxiliary agent is selected from at least one of vinylene carbonate, bisfluoroethylene carbonate, 1,3-propane sultone, vinyl sulfate, tris(trimethylsilane) phosphate and tris(trimethylsilane) phosphite.

6. A secondary battery, characterized in that: The invention comprises a positive electrode material, a negative electrode material and the non-aqueous electrolyte according to any one of claims 1 to 5.

7. The secondary battery according to claim 6, characterized in that: The positive electrode material is a lithium ion positive electrode material, and the electrolyte salt is a lithium salt.

8. The secondary battery according to claim 7, characterized in that: The chemical formula of the lithium ion cathode material is LiNi x Co y Mn z M 1-x-y-z O2 or LiNi x Co y Al z M 1-x-y-z O2, where M is at least one of Mg, Cu, Zn, Sn, B, Ga, Cr, Sr, V and Ti, 0.5 ≤ x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0.9 < x + y + z ≤ 1.

0. The anode material includes at least one of artificial graphite, natural graphite, silicon-oxygen composite material and silicon-carbon composite material. The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoroborate, lithium tetrafluoro(oxalato)phosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium 2-fluoromalonate difluoroborate.

9. The secondary battery according to claim 6, characterized in that: The positive electrode material is a sodium ion positive electrode material, and the electrolyte salt is a sodium salt.

10. The secondary battery according to claim 9, characterized in that: The chemical formula of the sodium ion cathode material is Na x M (1-y-z) Fe y Mn z O2, where M is at least one of Co, Ni, Cu, Mg, Zn, Al, Sn, Ga, Cr, Sr, V, and Ti, 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z ≤ 1. The anode material includes at least one of a carbon-based anode material, a titanium-based oxide anode material, and an alloy-based anode material. The sodium salt is selected from at least one of sodium hexafluorophosphate, sodium difluorophosphate, sodium bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium difluoro bis(oxalato)phosphate, sodium tetrafluoroborate, sodium bis(trifluoromethylsulfonyl)imide, and sodium bifluoride sulfonylimide.

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