Non-aqueous electrolyte and secondary battery

Abstract

The present invention provides a non-aqueous electrolyte and a secondary battery. The non-aqueous electrolyte includes an electrolyte salt, a non-aqueous organic solvent, and an additive. The additive includes a disulfonyl compound represented by Structural Formula I. Among them, 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 from 1 to 4. The non-aqueous electrolyte contains a disulfonyl compound, which can improve the kinetic performance and cycling performance of the battery regardless of whether it is in a fast charge or low temperature system, and is applicable to both lithium-ion batteries and sodium-ion batteries at the same time.

Description

Technical Field

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

[0002] Lithium-ion batteries have significant technical advantages compared to traditional batteries such as lead-acid batteries, nickel-cadmium batteries, and nickel-metal hydride batteries. Their energy density is much higher than that of other types of batteries, which means that under the same weight, lithium-ion batteries can provide longer battery life and stronger performance support. This characteristic makes lithium-ion batteries particularly suitable for fields that require lightweight and high endurance, such as laptops, smart wearable devices, and drones. In addition, lithium-ion batteries have a long cycle life, a low self-discharge rate, support fast charging, and have no memory effect. These features make lithium-ion batteries the preferred choice in many fields. With the increasing requirements for environmental protection and energy conservation and consumption reduction in society, the environmental protection and energy-saving advantages of lithium-ion batteries have become 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 energy, which helps to reduce the dependence on fossil fuels and achieve the goal of carbon neutrality. Moreover, the application fields of lithium-ion batteries are extensive and continuously expanding. From the early consumer electronics field to the new energy vehicle industry in recent years, lithium-ion batteries have played a crucial role. With the rapid development of the new energy vehicle market, power batteries have become one of the main application fields of lithium-ion batteries. In addition, lithium-ion batteries are gradually being applied in emerging markets such as energy storage systems, power tools, and industrial electronic devices.

[0003] However, with the continuous increase in the global demand for clean energy, the importance of energy storage technology has become increasingly prominent. As a new 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 they use sodium ions instead of lithium ions. Compared with lithium, sodium is more abundant in the earth's crust and cheaper in price, which gives sodium-ion batteries significant advantages in raw material acquisition and cost control. In addition, sodium-ion batteries also have characteristics such as high safety, good thermal stability, environmental friendliness, excellent 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, household energy storage systems, industrial and commercial energy storage, two-wheeled and three-wheeled electric vehicles, backup power supplies for communication base stations, and applications in low-temperature environments.

[0004] However, both lithium-ion batteries and sodium-ion batteries face some challenges. In fields such as electric vehicles and drones, higher and higher requirements are put forward for the fast charging performance, cycling 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 divinyl sulfone (DTD) can no longer meet the current requirements of lithium-ion batteries and sodium-ion batteries for fast charging and low-temperature fields. 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. The non-aqueous electrolyte contains a disulfonyl compound, which can improve the kinetic performance and cycling performance of the battery regardless of fast charging or low-temperature systems, and is applicable to both lithium-ion batteries and sodium-ion batteries at the same time.

[0006] To achieve the above purpose, the present invention provides a non-aqueous electrolyte on the one hand. The non-aqueous electrolyte includes an electrolyte salt, a non-aqueous organic solvent, and an additive. The additive includes a disulfonyl compound shown in Structural Formula I, wherein the structure of R1 is shown in Formula I, Formula II, Formula III, or Formula IV, R2 is a halogen, and n is an integer from 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 both a disulfonyl group (see Structural Formula I) and a cyclic sulfate (see Formula III and Formula IV) or a cyclic phosphate group (see Formula I and Formula II). Using this type of disulfonyl compound with multiple functional groups on the batteries of different battery systems can effectively form an SEI rich in sulfur or phosphorus elements 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 connecting two cyclic phosphates or cyclic sulfates in the middle, when the cyclic phosphate or cyclic sulfate is oxidized or reduced to form a film, Li x SO y components can be inserted in the middle, so as to form a phosphate polymer film-Li x SO y -phosphate polymer film type or sulfate polymer film-Li x SO y -sulfate polymer film type of 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 and low-temperature performance) and cycling 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 ratio of the disulfonyl compound in the non-aqueous electrolyte is 0.1% to 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 ratio of the auxiliary agent in the non-aqueous electrolyte is 0.5% to 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).

[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 bifluoride sulfonylimide. Detailed implementation manners

[0021] The secondary battery of the present invention has excellent rate performance, low-temperature performance, and cycling performance. The capacity retention rate can still reach more than 90% after 1000 cycles at a high voltage system of 4.35V, and can still reach more than 80% after 500 cycles at 4.35V and 4C systems. 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, its 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 matching negative electrode material can include at least one of artificial graphite, natural graphite, silicon oxide composite material, and silicon carbon composite material. If it is a sodium ion battery, its 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 percentage of the non-aqueous organic solvent in the electrolyte is 60% - 90%. Preferably, the mass percentage of the non-aqueous organic solvent is 80% - 90%. By way of example, the mass percentage 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 numerical 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 percentage of the electrolyte salt in the electrolyte is 10-25%. Preferably, the mass percentage of the electrolyte salt is 10-18%. As an example, the mass percentages of the electrolyte salt are 10%, 12%, 14%, 15%, 16%, 18%, 20%, 23%, 25%. The content of the electrolyte salt is not limited to the listed values, and other unlisted values within this 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(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 difluorobis(fluoromalonate)borate. 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 bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium difluorobis(oxalato)phosphate, sodium tetrafluoroborate, sodium bis(trifluoromethylsulfonyl)imide, and sodium bis(fluorosulfonyl)imide.

[0026] The additive includes a disulfonyl compound shown in Structural Formula Ⅰ, and the mass percentage of the disulfonyl compound in the electrolyte is 0.1-3.0%. Preferably, the mass percentage of the disulfonyl compound is 0.5-2.0%. As an example, the mass percentage 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%, 3.0%.

[0027] In the disulfonyl compound shown in Structural Formula Ⅰ, the structure of R1 is as shown in Formula One, Formula Two, Formula Three, or Formula Four, R2 is a halogen, and n is an integer from 1 to 4.

[0028]

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

[0030]

[0031]

[0032] The synthesis methods of Compound One to Compound Four are as shown in Reaction Formula One and Reaction Formula Two. In Reaction Formula One and Reaction Formula Two, the raw material disulfonyl chloride can refer to the synthesis process of 1,4-butane disulfonyl chloride in Patent CN118388378B. For disulfonyl compounds with different carbon chain lengths, only the raw material 1,4-dibromobutane needs to be replaced with dibromoalkanes with different carbon chain lengths, such as 1,2-dibromoethane, 1,3-dibromopropane, etc. The synthesis methods of Compound Five and Compound Six can refer to the synthesis method of Compound Four in Reaction Formula Two.

[0033]

[0034]

[0035] The non-aqueous electrolyte of the present invention may further include an auxiliary agent. The mass ratio of the auxiliary agent in the non-aqueous electrolyte is 0.5-10.5%. As an example, it can be, but is 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), difluoroethylene carbonate (DEPC), 1,3-propane sultone (PS), vinylene sulfate (DTD), tris(trimethylsilyl) phosphate (TMSP), and tris(trimethylsilyl) phosphite (TMSPi). Preferably, the auxiliary agent is vinylene carbonate or difluoroethylene carbonate, and the mass ratio thereof in the non-aqueous electrolyte is preferably 0.2-3.0%.

[0036] To better illustrate the purpose, technical solution, 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 methods described in the following embodiments are further explanatory descriptions of the present invention and should not be construed as limitations on the present invention.

[0037] For those not specifying specific conditions in the examples and comparative examples, they can be carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments not indicating the manufacturer, they are all conventional products that can be obtained through commercial channels.

[0038] Example 1

[0039] In a glove box filled with nitrogen (O2 < 1 ppm, H2O < 2 ppm), ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate were mixed evenly according to a volume ratio of 3:4:3 to prepare 85.5 g of a non-aqueous organic solvent. 0.5 g of a compound was added to obtain a mixed solution. The mixed solution was sealed and packed and placed in a freezer (-4°C) for 2 h and then taken out. In a glove box filled with nitrogen (O2 < 1 ppm, H2O < 2 ppm), 14.0 g of lithium hexafluorophosphate was slowly added to the mixed solution. After mixing evenly, the electrolyte was prepared.

[0040] Refer to Example 1 to prepare the electrolytes of Examples 2-14. The differences can be referred to Table 1. Replace the lithium salt in Example 1 with a sodium salt to prepare the electrolytes of Examples 15-20. The differences can be referred to Table 1. Refer to Example 1 and Example 15 to prepare the electrolytes of Comparative Examples 1-7. The differences can be referred to Table 1.

[0041] Among them, the lithium-ion batteries corresponding to Examples 1 to 14 and Comparative Examples 1 to 4 use LiNi 0.8 Co 0.1 Mn 0.1 O2 as the positive electrode material and artificial graphite as the negative electrode material. The sodium-ion batteries corresponding to Examples 15 to 20 and Comparative Examples 5 to 7 use 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 and hard carbon as the negative electrode material. The lithium-ion batteries and sodium-ion batteries can be synthesized with reference to the conventional battery preparation process.

[0042] Table 1 Electrolyte Formulations of the Batteries Corresponding to Examples 1 to 20 and Comparative Examples 1 to 7

[0043]

[0044]

[0045]

[0046] The structural formulas of Compound Seven in Comparative Examples 2 to 4 and Comparative Examples 6 to 7 are as follows.

[0047]

[0048] The batteries of Examples 1 to 20 and Comparative Examples 1 to 7 were respectively tested for their room-temperature cycle performance, high-rate cycle performance, and low-temperature discharge performance. The test conditions are as follows, and the test results are shown in Table 2.

[0049] (1) Room-temperature cycle performance test of the lithium-ion batteries of Examples 1 to 14 and Comparative Examples 1 to 4

[0050] The lithium-ion battery was placed in an environment of 25°C and charged at a constant current of 1C to 4.35V, then charged at a constant voltage until the current dropped to 0.05C, and then discharged at a constant current of 1C to 3.0V. This cycle was repeated, and the discharge capacity of the first cycle and the discharge capacity of the last cycle were recorded. The capacity retention rate of the high-temperature cycle was calculated according to the following formula.

[0051] Capacity retention rate = Discharge capacity of the last cycle / Discharge capacity of the first cycle × 100%

[0052] (2) High-rate cycle performance test of the lithium-ion batteries of Examples 1 to 14 and Comparative Examples 1 to 4

[0053] Place the lithium-ion battery in an environment at 25°C and charge it at a constant current of 4C until 4.35V, then charge it at a constant voltage until the current drops to 0.05C, and then discharge it at a constant current of 1C until 3.0V. Repeat this cycle and record the discharge capacity of the first cycle and the last cycle. Calculate the capacity retention rate of the high-temperature cycle according to the following formula.

[0054] Capacity retention rate = Discharge capacity of the last cycle / Discharge capacity of the first cycle × 100%

[0055] (3)Low-temperature discharge test of the lithium-ion batteries of Examples 1 to 14 and Comparative Examples 1 to 4

[0056] Place the lithium-ion battery in an environment at 25°C and charge it at a constant current of 1C until 4.35V, then charge it at a constant voltage until the current drops to 0.05C, and then discharge it at a constant current of 1C until 3.0V. Record the discharge capacity at this time as C0. Then charge it at a constant current of 1C until 4.35V, then charge it at a constant voltage until the current drops to 0.05C, and then place the battery in an environment at -20°C and let it stand for more than 4 hours, and discharge it at a constant current of 0.5C in an environment at -20°C until 3.0V. Record the discharge capacity at this time as C1.

[0057] Capacity retention rate = C1 / C0 × 100%

[0058] In addition, for 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, except that the maximum charging voltage is 4.2V, the rest are the same as the test conditions of the lithium-ion batteries.

[0059] Table 2 Test results of the battery performance of each example and comparative example

[0060]

[0061] As can be seen from the results in Table 2, the room-temperature cycle performance, high-rate cycle performance, and low-temperature discharge performance of Examples 1 to 20 are all better than those of Comparative Examples 1 to 7. This is because the additives in the non-aqueous electrolyte of Examples 1 to 20 include disulfonyl compounds, and the disulfonyl compounds have both disulfonyl groups and cyclic sulfate or cyclic phosphate groups at the same time. When such disulfonyl compounds with multiple functional groups are used in lithium-ion batteries or sodium-ion batteries, they can effectively form an SEI rich in sulfur or phosphorus elements on the positive and negative electrodes. In addition, the disulfonyl compounds are different from conventional cyclic phosphate additives and cyclic sulfate additives. Since there is a short-chain disulfonyl group in the middle connecting two cyclic phosphates or cyclic sulfates, when the cyclic phosphate or cyclic sulfate is oxidized or reduced to form a film, Li x SO y components can be inserted in the middle, so that a phosphate ester polymer film - Li xSO y -Phosphate ester polymer film type or sulfate ester polymer film - Li x SO y -SEI or CEI of sulfate ester polymer film type. This type of SEI or CEI is more ductile 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 cycling performance of the secondary battery.

[0062] From the comparison between Examples 1 - 6 and Comparative Example 2, and Examples 15 - 16 and Comparative Example 6, it can be seen that although Compound Seven is also a disulfonyl compound, the two ends of the disulfonate are ethylene carbonate compounds. And carbonate compounds or alkane compounds are prone to be oxidized at the positive electrode or reduced at the negative electrode to form an SEI of organic components. The SEI of organic components usually has a relatively large internal resistance and will cover the Li formed in the middle disulfonate x S y O z component, and will not form a phosphate ester polymer film - Li of this type of disulfonyl compound as in the present invention x S y O z -Phosphate ester polymer film type or sulfate ester polymer film - Li x S y O z -Sulfate ester polymer film structure, which inhibits the effect of the disulfonate itself, so the improvement of battery performance is not obvious.

[0063] Comparing Examples 1 - 6, it can be seen that when the disulfonyl compound is Compound One, the performance is better. This is because when the cyclic phosphate ester is oxidized or reduced to form a film, Compound One can insert Li in the middle x SO y component, so as to form a phosphate ester polymer film - Li x SO y -Phosphate ester polymer film, and because of the unique phosphite structure with strong reducibility, it can preferentially react with the oxygen free radicals released from the positive electrode, inhibiting the oxidation of the electrolyte by the oxygen free radicals released from the positive electrode.

[0064] Comparing Examples 9 - 14 and Examples 18 - 20, it can be seen that adding carbonate additives on the basis of disulfonyl compounds helps to improve the battery performance. This is because the phosphate ester polymer film - Li x SO y -Phosphate ester polymer film type or sulfate ester polymer film - Li x SO y- Although the SEI or CEI of the sulfate polymer film type has extremely high conductivity and low impedance, a certain amount of carbonate additives are still required to form a film to enhance the toughness of the SEI film, so that even when the negative electrode expands due to lithium intercalation, the SEI film is less likely to break, thus having more excellent cycle performance.

[0065] Combined with Comparative Examples 3-4 and Comparative Example 7, it can be seen that even on the basis of Compound VII, adding sulfate or phosphate additives, the battery performance is still not good, indicating that even adding sulfate or phosphate additives cannot overcome the negative impact brought by the large internal resistance SEI formed by carbonate compounds of disulfonyl compounds with ethylene carbonate compounds at both ends.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it is not limited to the embodiments listed. Those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions 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, and the mass proportion of the disulfonyl compound in the non-aqueous electrolyte is 0.1-3.0%, 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 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.

4. 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.

5. 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 4.

6. The secondary battery according to claim 5, characterized in that: The positive electrode material is a lithium ion positive electrode material, and the electrolyte salt is a lithium salt.

7. The secondary battery according to claim 6, 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.

8. The secondary battery according to claim 5, characterized in that: The positive electrode material is a sodium ion positive electrode material, and the electrolyte salt is a sodium salt.

9. The secondary battery according to claim 8, 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 difluorobis(oxalato)phosphate, sodium tetrafluoroborate, sodium bis(trifluoromethylsulfonyl)imide, and sodium bifluoride sulfonylimide.

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