High-voltage non-aqueous electrolyte and lithium battery

Abstract

In order to solve the problem that high and low temperature performance and the like of a lithium ion battery are difficult to consider, the invention provides the high-voltage non-aqueous electrolyte and the lithium battery. The non-aqueous electrolyte comprises an organic solvent, an electrolyte lithium salt and an additive, and the additive comprises 0.1%-2% of tripropargyl isocyanurate, 0.1%-20% of fluoroethylene carbonate, 0.1%-2% of 2-sulfobenzoic anhydride and 0.1%-1% of an isocyanate compound; the organic solvent comprises low-molecular-weight halogen atom substituted or unsubstituted carboxylic ester which accounts for more than 30% of the total mass of the non-aqueous electrolyte. Through the synergistic effect of all the components, catalytic decomposition of a conventional carbonic ester solvent in a high-voltage state is inhibited, gas production of the battery and dissolution of metal ions are inhibited, the high-temperature and normal-temperature performance of the lithium ion battery under high voltage is improved, the low-temperature performance and the rate performance of the battery are both considered, and the lithium ion battery has good application prospects. And inflation, cyclic attenuation and thickness increase of the lithium ion battery under a high-temperature condition can be inhibited.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to a high-voltage non-aqueous electrolyte and a lithium battery. BACKGROUND

[0002] With the emergence of emerging consumer fields such as mobile phones, tablet computers, smart wear and ETC, lithium ion batteries have shown great advantages due to their high energy density and long cycle life. However, with the continuous diversification of the functions of the corresponding devices and the continuous rise of the power consumption of the power modules, the conventional lithium ion battery has been difficult to meet the use requirements of users. In order to improve the user experience, the development direction of lithium ion batteries has become increasingly clear, that is, to improve the energy density as much as possible or to realize fast charging under safe conditions. In order to improve the energy density, the industry currently mainly develops from three aspects. One is to seek new material systems, such as lithium cobaltate, lithium-rich manganese-based, ternary high-nickel positive electrode materials, silicon-carbon negative electrode materials and the like; the second is to improve the cut-off charging voltage of the existing materials, such as 4.5V or above lithium cobaltate battery, 4.4V or above ternary battery and the like; the third is to improve the areal density and the compaction density by changing the battery process or to use thinner current collectors, adhesive tapes and aluminum plastic shells and the like. On the other hand, in order to quickly shorten the charging time so as to achieve the rated capacity, fast-charging lithium ion batteries have emerged, from the initial 0.2C charging to the later 2C charging, and even 5C charging.

[0003] In the digital field with high requirements for volume energy density, the design idea of lithium battery is high-voltage lithium cobaltate. The voltage of commercial lithium cobaltate battery has been gradually increased from the initial 4.2V to 4.5V, but at the same time, it also brings some negative effects, such as the material surface due to the existence of dangling bonds and unsaturated coordination relationship will make its reaction activity significantly higher than the bulk phase. When the lithium cobaltate battery is charged, the following reaction processes occur: (1) the positive electrode material starts to delithiate from the surface; (2) after delithiation, the Li layer oxygen atoms lose the barrier and produce repulsion, resulting in unstable surface structure; (3) continuous delithiation promotes surface lattice activity, and gas overflow occurs; (4) the overflow gas causes the surface Co atom to be poor in stability and to dissolve; (5) the dissolved high-valence Co element also oxidizes the electrolyte and participates in the electrolyte chemical reaction. The solid-liquid interface side reaction is an inevitable problem in the development of lithium batteries, and the chemical window of the non-aqueous organic electrolyte currently used is usually lower than 4.5V. When the charging cut-off voltage is higher than 4.5V, the electrolyte will be oxidized and decomposed on the surface of the battery, and this process causes the battery capacity to sharply "dive". At the same time, the products of oxidation and decomposition also cover the surface of the electrode material to increase the internal resistance of the battery. The free transition metal elements catalyze the surface side reaction products to separate, which brings hidden dangers to the high-activity state of the electrode material.

[0004] Therefore, it is necessary to develop an electrolyte which can balance the high and low temperature, cycle and rate performance at high voltage. SUMMARY

[0005] The purpose of this invention is to provide an electrolyte and lithium battery that can take into account high and low temperature performance, cycle performance, and rate performance under high voltage.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention provides a non-aqueous electrolyte comprising an organic solvent, an electrolyte lithium salt, and additives. The additives include 0.1% to 2% of triargyl isocyanurate, 0.1% to 20% of fluoroethylene carbonate, 0.1% to 2% of 2-sulfobenzoic anhydride, and 0.1% to 1% of isocyanate compounds, by mass of the non-aqueous electrolyte. The organic solvent comprises at least 30% of low molecular weight halogen-substituted or unsubstituted carboxylic acid esters by mass of the non-aqueous electrolyte.

[0008] According to some specific embodiments, the isocyanate compound is selected from one or more of hexamethylene diisocyanate, 1,5-diisocyanate pentane, ethyl isocyanate acrylate, and isocyanoethyl methacrylate.

[0009] According to some specific embodiments, the substitution in the halogen-substituted or unsubstituted carboxylic acid ester is preferably fluorine substitution.

[0010] According to some specific embodiments, the low molecular weight halogen-substituted or unsubstituted carboxylic acid ester is selected from one or more of 2,2-difluoroethyl acetate, ethyl acetate, propyl acetate, and methyl acetate.

[0011] According to some specific embodiments, the additive also includes other additives, which are one or more of the following: vinylene carbonate, ethylene ethylene carbonate, 1,3-propane sulpholactone, 1,3-(1-propene) sulpholactone, methane disulfonate, tris(trimethylsilane)borate, tris(trimethylsilane) phosphate, methyl cis-butene anhydride, succinic anhydride, biphenyl, cyclohexylbenzene, trioctyl phosphate, succinic anhydride, adiponitrile, 1,3,6-hexanetrionitrile, 1,2-di(2-cyanoethoxy)ethane, 1,4-dicyano-2-butene, 1,2,3-tris(2-cyanoethoxy)propane, decanonitrile, 1,2,3,4,5-penta(2-cyanoethoxy)pentane, and lithium difluorooxalate borate.

[0012] Furthermore, the mass of the other additives is 0.1% to 30% of the total mass of the non-aqueous electrolyte.

[0013] Furthermore, the mass of the other additives is 1% to 20% of the total mass of the non-aqueous electrolyte.

[0014] Further, the mass of the other additives is 1% to 15% of the total mass of the nonaqueous electrolyte, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.

[0015] According to some embodiments, the organic solvent is all the low-molecular-weight halogen-substituted or unsubstituted carboxylate.

[0016] According to some other embodiments, the organic solvent further comprises other organic solvents, which comprise a mixture of cyclic esters and chain esters, the cyclic ester being one or more of γ-butyrolactone, ethylene carbonate, propylene carbonate, and the chain ester being one or more of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl fluoropropionate, and ethyl fluoropropionate.

[0017] Further, the organic solvent is a mixture of chain ester, cyclic ester, and low-molecular-weight halogen-substituted or unsubstituted carboxylate in a volume ratio of 1:2 to 4:5 to 7.

[0018] According to some embodiments, the electrolyte lithium salt is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(trifluoromethylsulfonyl)imide, lithium difluorophosphate, lithium trifluoromethylsulfonate, and lithium bisfluorosulfonylimide.

[0019] According to some embodiments, the concentration of the electrolyte lithium salt is 0.8 to 3 mol / L, for example, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, or 3 mol / L.

[0020] According to some embodiments, the mass of the tripropargyl isocyanurate is 0.1% to 2% of the total mass of the nonaqueous electrolyte, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%. Further, the mass of the tripropargyl isocyanurate is 0.1% to 1% of the total mass of the nonaqueous electrolyte.

[0021] According to some embodiments, the mass of the fluorinated ethylene carbonate is 0.1% to 20% of the total mass of the nonaqueous electrolyte, for example, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%. Further, the mass of the fluorinated ethylene carbonate is 4% to 20% of the total mass of the nonaqueous electrolyte.

[0022] According to some embodiments, the mass of the 2-sulfobenzoic anhydride is 0.1% to 2% of the total mass of the nonaqueous electrolyte, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%. Further, the mass of the 2-sulfobenzoic anhydride is 0.1% to 1.5% of the total mass of the nonaqueous electrolyte.

[0023] According to some embodiments, the mass of the isocyanate compound is 0.1% to 1% of the total mass of the nonaqueous electrolyte, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%.

[0024] According to some embodiments, the mass of the low-molecular-weight halogen-substituted or unsubstituted carboxylic acid ester is more than 30%, more than 31%, more than 32%, more than 33%, more than 34%, more than 35%, more than 36%, more than 37%, more than 38%, more than 39%, or more than 40% of the total mass of the nonaqueous electrolyte.

[0025] A second aspect of the present application provides a lithium battery including a positive electrode, a negative electrode, and an electrolyte, the electrolyte being the above-described electrolyte.

[0026] According to some embodiments, the active material of the positive electrode is lithium cobaltate.

[0027] According to some embodiments, the charging cut-off voltage of the lithium battery is above 4.5V.

[0028] Thanks to the above technical solution, the present application has the following advantages compared with the prior art:

[0029] The present application inhibits the catalytic decomposition of conventional carbonate solvents under high voltage, inhibits the gas production and metal ion elution of the battery, improves the high temperature and normal temperature performance of the lithium ion battery under high voltage, takes into account the low temperature and rate performance of the battery, and can also inhibit the gas swelling, cycle attenuation and thickness increase of the lithium ion battery under high temperature. The non-aqueous electrolyte of the present application is suitable for high-voltage, high-specific-energy system lithium ion secondary batteries. DETAILED DESCRIPTION

[0030] The present application will be further described below in conjunction with examples. However, the present application is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different specific requirements. The implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present application can be combined with each other as long as there is no conflict between them.

[0031] Unless otherwise specified, the reagents, instruments and the like used in the following examples and comparative examples are commercially available products commonly used in the art, or can also be prepared by conventional methods in the art.

[0032] The abbreviations of various substances in this text are as follows:

[0033] Diethyl carbonate: DEC; ethylene carbonate: EC; propylene carbonate: PC; ethyl acetate: EA; 2,2-difluoroethyl acetate: DFEA; propyl acetate: PA; ethyl propionate: EP; propyl propionate: PP.

[0034] The abbreviation of fluoroethylene carbonate is FEC, and the CAS number is 114435-02-8.

[0035] 2-Sulfobenzoic anhydride: CAS registration number 81-08-3.

[0036] The structural formula of tripropargyl isocyanurate is

[0037] The structural formula of 1,2,3,4,5-penta(2-cyanoethyloxy)pentane is as follows:

[0038]

[0039] The preparation method of 1,2,3,4,5-penta(2-cyanoethyloxy)pentane is as follows: 152 g of xylitol is mixed with 6.8 g of sodium ethoxide, and then heated to 90°C and stirred for 2 hours. Then 477 g of acrylonitrile is slowly added and stirred. After 12 hours of reaction, the temperature is lowered to room temperature. Then 6000 g of ethanol is added and stirred uniformly. Filtration is performed to obtain filter residue. The filter residue is recrystallized with ethyl acetate and n-hexane to obtain the finished product with a purity of >99%.

[0040] 1,5-diisocyanate pentane: CAS No. 4538-42-5.

[0041] Isocyanate ethyl acrylate: CAS No. 13641-96-8.

[0042] Isocyanatoethyl methacrylate: CAS No. 30674-80-7.

[0043] Example 1:

[0044] In an argon-filled glove box (H2O content <10 ppm), DEC, EC, PC, EA and DFEA are mixed uniformly at a volume ratio of 1:2:1:3:3. LiPF6 is added to the mixed solution, and then fluoroethylene carbonate, 2-sulfobenzoic anhydride, tripropargyl isocyanurate, succindinitrile, 1,3,6-hexanetricarbonitrile and hexamethylene diisocyanate are added respectively to obtain an electrolyte. In the electrolyte, the concentration of LiPF6 is 1.2 mol / L, the content of fluoroethylene carbonate is 4 wt%, the content of 2-sulfobenzoic anhydride is 0.5 wt%, the content of tripropargyl isocyanurate is 0.2 wt%, the content of succindinitrile is 2 wt%, the content of 1,3,6-hexanetricarbonitrile is 3 wt%, and the content of hexamethylene diisocyanate is 0.5 wt%.

[0045] Example 2:

[0046] The same as example 1, except that the content of tripropargyl isocyanurate in this example is 0.5 wt%.

[0047] Example 3:

[0048] The same as example 1, except that the content of tripropargyl isocyanurate in this example is 1 wt%.

[0049] Example 4:

[0050] The same as example 1, except that the content of tripropargyl isocyanurate in this example is 1.5 wt%.

[0051] Example 5:

[0052] Example 2 except that the content of 2-sulfobenzoic anhydride in this example is 0.2 wt%.

[0053] Example 6:

[0054] Example 2 except that the content of 2-sulfobenzoic anhydride in this example is 1 wt%.

[0055] Example 7:

[0056] Example 2 except that the content of 2-sulfobenzoic anhydride in this example is 1.5 wt%.

[0057] Example 8:

[0058] Example 2 except that the content of fluoroethylene carbonate in this example is 2 wt%.

[0059] Example 9:

[0060] Example 2 except that the content of fluoroethylene carbonate in this example is 6 wt%.

[0061] Example 10:

[0062] Example 2 except that the content of fluoroethylene carbonate in this example is 8 wt%.

[0063] Example 11:

[0064] Example 2 except that the content of fluoroethylene carbonate in this example is 10 wt%.

[0065] Example 12:

[0066] Example 2 except that the solvent in this example is a mixture of DEC, EC, PC, and EA at a volume ratio of 1:2:1:6.

[0067] Example 13:

[0068] Example 2 except that the solvent in this example is a mixture of DEC, EC, PC, and PA at a volume ratio of 1:2:1:6.

[0069] Example 14:

[0070] Example 2 except that the solvent in this example is a mixture of DEC, EC, PC, and DFEA at a volume ratio of 1:2:1:6.

[0071] Example 15:

[0072] The same as Example 2 except that the solvent in this example is a mixture of DEC, EC, PC, PA and DFEA in a volume ratio of 1:2:1:3:3.

[0073] Example 16:

[0074] The same as Example 2 except that the solvent in this example is a mixture of DEC, EC, PC, EA and PA in a volume ratio of 1:2:1:3:3.

[0075] Example 17:

[0076] The same as Example 2 except that the solvent in this example is DFEA.

[0077] Example 18:

[0078] The same as Example 2 except that the electrolyte in this example further contains 0.5wt% of lithium difluoro(oxalato)borate.

[0079] Example 19:

[0080] The same as Example 2 except that the electrolyte in this example further contains 2wt% of 1,3-propane sultone.

[0081] Example 20:

[0082] The same as Example 2 except that the content of 1,3,6-hexanetricarbonitrile in this example is 1wt%, and the electrolyte in this example further contains 1wt% of 1,2,3,4,5-penta(2-cyanoethoxy)pentane.

[0083] Example 21:

[0084] The same as Example 2 except that 1,5-diisocyanate pentane is used in this example instead of hexamethylene diisocyanate in Example 2.

[0085] Example 22:

[0086] The same as Example 2 except that isocyanate acrylate is used in this example instead of hexamethylene diisocyanate in Example 2.

[0087] Example 23:

[0088] The same as Example 2 except that isocyanate acrylate is used in this example instead of hexamethylene diisocyanate in Example 2.

[0089] Comparative Example 1:

[0090] In an argon-filled glove box (H2O content < 10 ppm), DEC, EC, PC, EP and PP were mixed uniformly at a volume ratio of 1:2:1:3:3, LiPF6 was added to the mixed solution, and then malononitrile and 1,3,6-hexanetricarbonitrile were added to the electrolyte, respectively. In the electrolyte, the concentration of LiPF6 was 1.2 mol / L, the content of malononitrile was 2wt%, and the content of 1,3,6-hexanetricarbonitrile was 3wt%.

[0091] Comparative Example 2:

[0092] In an argon-filled glove box (H2O content < 10 ppm), DEC, EC, PC, EP and PP were mixed uniformly at a volume ratio of 1:2:1:3:3, LiPF6 was added to the mixed solution, and then malononitrile and 1,3,6-hexanetricarbonitrile were added to the electrolyte, respectively. In the electrolyte, the concentration of LiPF6 was 1.2 mol / L, the content of malononitrile was 2wt%, and the content of 1,3,6-hexanetricarbonitrile was 3wt%.

[0093] Comparative Example 3:

[0094] In an argon-filled glove box (H2O content < 10 ppm), DEC, EC, PC, EA and DFEA were mixed uniformly at a volume ratio of 1:2:1:3:3, LiPF6 was added to the mixed solution, and then malononitrile and 1,3,6-hexanetricarbonitrile were added to the electrolyte, respectively. In the electrolyte, the concentration of LiPF6 was 1.2 mol / L, the content of malononitrile was 2wt%, and the content of 1,3,6-hexanetricarbonitrile was 3wt%.

[0095] Performance test:

[0096] The electrolyte prepared in the above Examples 1 to 23 and Comparative Examples 1 to 3 was subjected to performance test in a 4.55V lithium cobalt oxide-graphite battery, respectively.

[0097] (1) Test the capacity retention rate at 85℃ high temperature for 4 hours and the battery swelling rate

[0098] The battery was charged to 4.55 V at 1 C under constant current / constant voltage (CC / CV) conditions at 25 °C, then left in an oven at 85 °C for 4 hours, and after the rest, discharged to 3.0 V at 1 C, and the capacity and battery thickness were tested. The above-mentioned battery was tested after being charged under the same conditions, and the capacity and battery thickness after being discharged under the same conditions without high-temperature rest. Among them, the capacity retention rate of 85 °C high-temperature rest for 4 hours is equal to the capacity of 85 °C high-temperature rest for 4 hours divided by the capacity without high-temperature rest; the battery swelling rate of 85 °C high-temperature rest for 4 hours, that is, the difference between the battery thickness after rest and the battery thickness before rest divided by the battery thickness before rest.

[0099] (2) 45 °C 200 cycle capacity retention rate

[0100] The battery was charged to 4.55 V at 1 C under constant current / constant voltage (CC / CV) conditions at 45 °C, then discharged to 3.0 V at 1 C, and so on for 200 cycles of charge and discharge, and the battery capacity after the first charge and discharge and the battery capacity after 200 cycles of cycle charge and discharge were tested respectively. The 45 °C 200 cycle capacity retention rate is equal to the battery capacity after 200 cycles of cycle charge and discharge divided by the battery capacity after the first charge and discharge.

[0101] (3) DCR of 50% SCO, 2C 10s

[0102] The voltage difference and current ratio of the above-mentioned 4.55 V lithium cobaltate graphite battery at 50% SCO state of charge, 2C constant current discharge for 10s were tested respectively.

[0103] (4) -20 °C low-temperature discharge test

[0104] The battery was charged to 4.55 V at 1 C under constant current / constant voltage (CC / CV) conditions at 25 °C, then discharged at 1 C at -20 °C. The -20 °C discharge efficiency is the -20 °C discharge capacity divided by the 20 °C charge capacity.

[0105] The relevant experimental data are shown in Table 1.

[0106] Table 1

[0107]

[0108]

[0109] As can be seen from Examples 1 to 23 and Comparative Example 2 in Table 1, the fluoroethylene carbonate of the present application can significantly improve the cycle performance of the battery, the trispropargyl isocyanurate and isocyanate compound improves the high-temperature performance while deteriorating the low-temperature and rate performance of the battery, the low-molecular-weight halogen-substituted or unsubstituted carboxylate improves the low-temperature and rate performance, through the synergistic effect of the components, the catalytic decomposition of the conventional carbonate solvent under high-voltage conditions is inhibited, the gas production and metal ion elution of the battery are inhibited, the high-temperature and normal-temperature performance of the lithium ion battery under high voltage is improved, the low-temperature and rate performance of the battery is taken into account, and the lithium ion battery under high-temperature conditions can also be inhibited from swelling, cycle attenuation and thickness increase.

[0110] The above detailed description of the present application is intended to enable those skilled in the art to understand and implement the present application, and is not intended to limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A non-aqueous electrolyte, comprising an organic solvent, a lithium electrolyte salt, and additives, characterized in that: The additives include 0.1% to 2% of triargyl isocyanurate, 0.1% to 20% of fluoroethylene carbonate, 0.1% to 2% of 2-sulfobenzoic anhydride, and 0.1% to 1% of isocyanate compounds, by weight of 0.1% to 2% of the total mass of the non-aqueous electrolyte; the organic solvent includes low molecular weight halogen-substituted or unsubstituted carboxylic acid esters, by weight of 30% or more of the total mass of the non-aqueous electrolyte.

2. The non-aqueous electrolyte according to claim 1, characterized in that: The isocyanate compound is selected from one or more of hexamethylene diisocyanate, 1,5-diisocyanate pentane, ethyl isocyanate acrylate, and isocyanoethyl methacrylate.

3. The non-aqueous electrolyte according to claim 1, characterized in that: The low molecular weight halogen-substituted or unsubstituted carboxylic acid esters are selected from one or more of 2,2-difluoroethyl acetate, ethyl acetate, propyl acetate, and methyl acetate.

4. The non-aqueous electrolyte according to claim 1, characterized in that: The additives also include other additives, which are one or more of the following: vinylene carbonate, ethylene ethylene carbonate, 1,3-propane sulpholactone, 1,3-(1-propene) sulpholactone, methane disulfonate, tris(trimethylsilane)borate, tris(trimethylsilane) phosphate, methyl cis-butene anhydride, succinic anhydride, biphenyl, cyclohexylbenzene, trioctyl phosphate, succinic anhydride, adiponitrile, 1,3,6-hexanetrionitrile, 1,2-di(2-cyanoethoxy)ethane, 1,4-dicyano-2-butene, 1,2,3-tris(2-cyanoethoxy)propane, decanonitrile, 1,2,3,4,5-penta(2-cyanoethoxy)pentane, and lithium difluorooxalate borate.

5. The non-aqueous electrolyte according to claim 4, characterized in that: The other additives are present in an amount of 0.1% to 30% of the total mass of the non-aqueous electrolyte.

6. The non-aqueous electrolyte according to claim 1, characterized in that: The organic solvent is entirely composed of the low molecular weight halogen-substituted or unsubstituted carboxylic acid esters; or, The organic solvent also includes other organic solvents, which include a mixture of cyclic esters and chain esters. The cyclic esters are one or more of γ-butyrolactone, ethylene carbonate, and propylene carbonate; the chain esters are one or more of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl fluoropropionate, and ethyl fluoropropionate.

7. The non-aqueous electrolyte according to claim 1, characterized in that: The electrolyte lithium salt is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, anhydrous lithium perchlorate, lithium di(trifluoromethanesulfonyl)imide, lithium difluorophosphate, lithium trifluoromethanesulfonate, and lithium difluorosulfonylimide; the concentration of the electrolyte lithium salt is 0.8–3 mol / L.

8. The non-aqueous electrolyte according to claim 1, characterized in that: The mass of the triargyl isocyanurate accounts for 0.1% to 1% of the total mass of the non-aqueous electrolyte, the mass of the fluoroethylene carbonate accounts for 4% to 20% of the total mass of the non-aqueous electrolyte, and the mass of the 2-sulfobenzoic anhydride accounts for 0.1% to 1.5% of the total mass of the non-aqueous electrolyte.

9. A lithium battery, comprising a positive electrode, a negative electrode, and an electrolyte, characterized in that: The electrolyte is the electrolyte according to any one of claims 1 to 8.

10. The lithium battery according to claim 9, characterized in that: The active material of the positive electrode is lithium cobalt oxide; the charging cut-off voltage of the lithium battery is above 4.5V.

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