ELECTROLYTE ADDITIVE, ELECTROLYTE AND LITHIUM-ION BATTERY

Abstract

An electrolyte additive, an electrolyte, and a lithium-ion battery, where the electrolyte additive has a structure shown in formula (I):

##STR00001##

The electrolyte additive has both a film-forming property and the property of inhibiting the rise of acidity and chromaticity of the electrolyte, thereby effectively improving the cycle performance of the battery.

Claims

1. An electrolyte additive, having a structure shown in Formula (I): ##STR00023## one of X.sub.1, X.sub.2, X.sub.3 and X.sub.4 is N, and the rest are CR.sub.1; R.sub.1 is selected from: H, a 5-6 membered aryl, a 5-6 membered heteroaryl, a C.sub.1-8 alkyl, a C.sub.2-8 alkenyl, a C.sub.0-8 alkylsilyl, a R.sub.0 substituted 5-6 membered aryl, a R.sub.0 substituted 5-6 membered heteroaryl, a R.sub.0 substituted C.sub.1-8 alkyl, a R.sub.0 substituted C.sub.2-8 alkenyl, or a R.sub.0 substituted C.sub.0-8 alkylsilyl; R is selected from: a 5-6 membered aryl, a 5-6 membered heteroaryl, a C.sub.1-8 alkyl, a C.sub.2-8 alkenyl, a C.sub.0-8 alkylsilyl, a R.sub.0 substituted 5-6 membered aryl, a R.sub.0 substituted 5-6 membered heteroaryl, a R.sub.0 substituted C.sub.1-8 alkyl, a R.sub.0 substituted C.sub.2-8 alkenyl, or a R.sub.0 substituted C.sub.0-8 alkylsilyl; R.sub.0 is selected from: a C.sub.1-6 alkyl, a C.sub.1-6 alkoxy or a halogen.

2. The electrolyte additive according to claim 1, wherein X.sub.3 is N, and X.sub.1, X.sub.2 and X.sub.4 are CH.

3. The electrolyte additive according to claim 1, wherein the 5-6 membered heteroaryl is selected from: furyl, thienyl, pyrrolyl, pyrazolyl, triazolyl, thiazolyl, imidazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl or triazinyl; R.sub.0 is selected from: a C.sub.1-4 alkyl or a halogen.

4. The electrolyte additive according to claim 1, wherein R is selected from: phenyl, thienyl, imidazolyl, pyridyl, fluorophenyl, fluorothienyl, fluorimidazolyl, fluoropyridyl, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-methyl-1-propyl, 2-butyl, fluoromethyl, fluoroethyl, fluoro-1-propyl, fluoro-2-propyl, fluoro-1-butyl, fluoro-2-methyl-1-propyl, fluoro-2-butyl, vinyl, propenyl, butenyl, fluorovinyl, fluoropropenyl, fluorobutenyl, trimethylsilyl, triethylsilyl, trifluorosilyl, tri(trifluoromethyl)dimethylsilyl, di(trifluoromethyl)methylsilyl, or tris(trifluoromethyl)silyl.

5. The electrolyte additive according to claim 1, wherein the electrolyte additive is selected from any one of the following compounds: ##STR00024##

6. An electrolyte, comprising an additive, wherein the additive comprises a first additive, the first additive is the electrolyte additive according to claim 1.

7. The electrolyte according to claim 6, wherein X.sub.3 is N, and X.sub.1, X.sub.2 and X.sub.4 are CH.

8. The electrolyte according to claim 6, wherein the 5-6 membered heteroaryl is selected from: furyl, thienyl, pyrrolyl, pyrazolyl, triazolyl, thiazolyl, imidazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl or triazinyl; R.sub.0 is selected from: a C.sub.1-4 alkyl or a halogen.

9. The electrolyte according to claim 6, wherein R is selected from: phenyl, thienyl, imidazolyl, pyridyl, fluorophenyl, fluorothienyl, fluorimidazolyl, fluoropyridyl, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-methyl-1-propyl, 2-butyl, fluoromethyl, fluoroethyl, fluoro-1-propyl, fluoro-2-propyl, fluoro-1-butyl, fluoro-2-methyl-1-propyl, fluoro-2-butyl, vinyl, propenyl, butenyl, fluorovinyl, fluoropropenyl, fluorobutenyl, trimethylsilyl, triethylsilyl, trifluorosilyl, tri(trifluoromethyl)dimethylsilyl, di(trifluoromethyl)methylsilyl, or tris(trifluoromethyl)silyl.

10. The electrolyte according to claim 6, wherein the electrolyte additive is selected from any one of the following compounds: ##STR00025##

11. The electrolyte according to claim 6, wherein the additive further comprises a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

12. The electrolyte according to claim 7, wherein the additive further comprises a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

13. The electrolyte according to claim 8, wherein the additive further comprises a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

14. The electrolyte according to claim 9, wherein the additive further comprises a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

15. The electrolyte according to claim 10, wherein the additive further comprises a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

16. The electrolyte according to claim 6, further comprising a lithium salt and a solvent, wherein in the electrolyte, the additive is 0.01% to 30%, the lithium salt is 5% to 20% and the solvent is 50% to 94.9%, by mass percent.

17. The electrolyte according to claim 10, further comprising a lithium salt and a solvent, wherein in the electrolyte, the additive is 0.01% to 30%, the lithium salt is 5% to 20% and the solvent is 50% to 94.9%, by mass percent.

18. The electrolyte according to claim 11, wherein the additive further comprises a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

19. The electrolyte according to claim 15, wherein the additive further comprises a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

20. The electrolyte according to claim 16, wherein the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorophosphate, lithium difluoroxalate phosphate and lithium bis(fluorosulfonyl)imide, and/or the solvent comprises at least one of a cyclic solvent and a linear solvent, wherein the cyclic solvent is selected from at least one of ethylene carbonate, propylene carbonate, -butyrolactone, phenyl acetate, 1,4-butane sultone and propylene 3,3,3-trifluorocarbonate; and the linear solvent is selected from at least one of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl acetate, methyl propyl carbonate, propyl propionate, 1,1,2,2-tetrafluorothyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and methyl 2,2-difluoroethyl carbonate.

21. The electrolyte according to claim 17, wherein the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorophosphate, lithium difluoroxalate phosphate and lithium bis(fluorosulfonyl)imide, and/or the solvent comprises at least one of a cyclic solvent and a linear solvent, wherein the cyclic solvent is selected from at least one of ethylene carbonate, propylene carbonate, -butyrolactone, phenyl acetate, 1,4-butane sultone and propylene 3,3,3-trifluorocarbonate; and the linear solvent is selected from at least one of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl acetate, methyl propyl carbonate, propyl propionate, 1,1,2,2-tetrafluorothyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and methyl 2,2-difluoroethyl carbonate.

22. The electrolyte according to claim 18, wherein the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorophosphate, lithium difluoroxalate phosphate and lithium bis(fluorosulfonyl)imide, and/or the solvent comprises at least one of a cyclic solvent and a linear solvent, wherein the cyclic solvent is selected from at least one of ethylene carbonate, propylene carbonate, -butyrolactone, phenyl acetate, 1,4-butane sultone and propylene 3,3,3-trifluorocarbonate; and the linear solvent is selected from at least one of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl acetate, methyl propyl carbonate, propyl propionate, 1,1,2,2-tetrafluorothyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and methyl 2,2-difluoroethyl carbonate.

23. The electrolyte according to claim 19, wherein the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorophosphate, lithium difluoroxalate phosphate and lithium bis(fluorosulfonyl)imide, and/or the solvent comprises at least one of a cyclic solvent and a linear solvent, wherein the cyclic solvent is selected from at least one of ethylene carbonate, propylene carbonate, -butyrolactone, phenyl acetate, 1,4-butane sultone and propylene 3,3,3-trifluorocarbonate; and the linear solvent is selected from at least one of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl acetate, methyl propyl carbonate, propyl propionate, 1,1,2,2-tetrafluorothyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and methyl 2,2-difluoroethyl carbonate.

24. A lithium-ion battery, comprising a positive electrode material, a negative electrode material and the electrolyte according to claim 6.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 shows views of electrolytes of Comparative Example 1, Comparative Example 2, Example 4, Example 6, Example 7 and Example 8 before and after storage.

[0017] FIG. 2 is dQ/dV curve diagrams of Comparative Example 1, Comparative Example 2 and Example 4.

DESCRIPTION OF EMBODIMENTS

[0018] In order to facilitate the understanding of the present disclosure, a more comprehensive description of the present disclosure will be given below, and preferred embodiments of the present disclosure are given. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to enable a more thorough and comprehensive understanding of the disclosed content of the present disclosure.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by the skilled in the field of the present disclosure. The terms used in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The terms and/or used herein include any and all combinations of one or more relevant listed items.

Explanations of Terms

[0020] The term alkyl refers to a saturated hydrocarbon containing a primary (positive) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. A phrase including the term, for example, C.sub.1-8 alkyl refers to an alkyl containing 1 to 8 carbon atoms. Suitable examples include, but are not limited to: methyl (Me, CH.sub.3), ethyl (Et, CH.sub.2CH.sub.3), 1-propyl (n-Pr, n-propyl, CH.sub.2CH.sub.2CH.sub.3), 2-propyl (i-Pr, i-propyl, CH(CH.sub.3).sub.2), 1-butyl (n-Bu, n-butyl, CH.sub.2CH.sub.2CH.sub.2CH.sub.3), 2-methyl-1-propyl (i-Bu, i-butyl, CH.sub.2CH(CH.sub.3).sub.2), 2-butyl (s-Bu, s-butyl, CH(CH.sub.3)CH.sub.2CH.sub.3), 2-methyl-2-propyl (t-Bu, t-butyl, C(CH.sub.3).sub.3), 1-pentyl (n-pentyl, CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.3), 2-pentyl (CH(CH.sub.3)CH.sub.2CH.sub.2CH.sub.3), 3-pentyl (CH(CH.sub.2CH.sub.3).sub.2), 2-methyl-2-butyl (C(CH.sub.3).sub.2CH.sub.2CH.sub.3), 3-methyl-2-butyl (CH(CH.sub.3)CH(CH.sub.3).sub.2), 3-methyl-1-butyl (CH.sub.2CH.sub.2CH(CH.sub.3).sub.2), 2-methyl-1-butyl (CH.sub.2CH(CH.sub.3)CH.sub.2CH.sub.3), 1-hexyl (CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.3), 2-hexyl (CH(CH.sub.3)CH.sub.2CH.sub.2CH.sub.2CH.sub.3), 3-hexyl (CH(CH.sub.2CH.sub.3)(CH.sub.2CH.sub.2CH.sub.3)), 2-methyl-2-pentyl (C(CH.sub.3).sub.2CH.sub.2CH.sub.2CH.sub.3), 3-methyl-2-pentyl (CH(CH.sub.3)CH(CH.sub.3)CH.sub.2CH.sub.3), 4-methyl-2-pentyl (CH(CH.sub.3)CH.sub.2CH(CH.sub.3).sub.2), 3-methyl-3-pentyl (C(CH.sub.3)(CH.sub.2CH.sub.3).sub.2), 2-methyl-3-pentyl (CH(CH.sub.2CH.sub.3)CH(CH.sub.3).sub.2), 2,3-dimethyl-2-butyl (C(CH.sub.3).sub.2CH (CH.sub.3).sub.2), 3,3-dimethyl-2-butyl (CH(CH.sub.3)C(CH.sub.3).sub.3 and octyl ((CH.sub.2).sub.7CH.sub.3).

[0021] Alkenyl refers to a hydrocarbon containing a normal, secondary, tertiary or cyclic carbon atom with at least one unsaturated site, i.e., a carbon-carbon sp.sup.2 double bond. A phrase including the term, for example, C.sub.2-8 alkenyl refers to an alkenyl group containing 2 to 8 carbon atoms. Suitable examples include, but are not limited to: vinyl (CHCH.sub.2), propenyl (CH.sub.2CHCH.sub.2), cyclopentenyl (C.sub.5H.sub.7) and 5-hexenyl (CH.sub.2CH.sub.2CH.sub.2CH.sub.2CHCH.sub.2).

[0022] Heteroaryl refers to an aryl group in which at least one carbon atom is substituted with a non-carbon atom, where the non-carbon atom can be N atom, O atom, S atom and so on. Suitable examples include, but are not limited to: furan, benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole, imidazole, oxazole, oxadiazole, thiazole, tetrazole, indole, carbazole, pyrroloimidazole, pyrrolopyrrole, thienopyrrole, thienothiophene, furanopyrrole, furanofuran, thienofuran, benzoisoxazole, benzoisothiazole, benzimidazole, pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, cinnoline, quinoxaline, phenanthridine, perimidine, quinazoline and quinazolinone.

[0023] Halogen or halogen atom refers to F, Cl, Br or I.

[0024] The term halogen substituted or halogenated denotes that H at any position and in any number on a corresponding group is substituted with a halogen; for example, fluoromethyl, including monofluoromethyl, difluoromethyl, trifluoromethyl; for example, fluoroethyl including but is not limited to, CH.sub.3CH.sub.2F, CH.sub.2FCH.sub.2F, CF.sub.2HCH.sub.3, CF.sub.3CH.sub.3, CF.sub.3CF.sub.3, etc.

[0025] Silicon group or silyl refers to

##STR00003##

in which R may be an acceptable group in the field, such as C.sub.1-8 alkyl, C.sub.1-6 alkyl, or C.sub.1-4 alkyl, H or halogen (for example, F); and in which a plurality of R may be the same or different from each other.

[0026] C.sub.0-8 alkylsilyl refers to

##STR00004##

in which R is C.sub.0-8 alkyl, and it can be understood that when R is C.sub.0 alkyl, it means that in

##STR00005##

R contains no carbon atom, that is, all R is H, equivalent to

##STR00006## [0027] halogen substituted C.sub.0-8 alkylsilyl refers to that in

##STR00007##

R is halogen substituted C.sub.0-8 alkyl, and when R is C.sub.0 alkyl, it means that in

##STR00008##

R contains no carbon atom, R is H or halogen, and at least one R is halogen, such as fluorine-substituted C.sub.0 alkylsilyl, equivalent to

##STR00009##

[0028] Detailed Explanation

[0029] An embodiment of the present disclosure provides an electrolyte additive with a structure shown in Formula (I):

##STR00010## [0030] one of X.sub.1, X.sub.2, X.sub.3 and X.sub.4 is N, and the rest are CR.sub.1; [0031] R.sub.1 is selected from: H, a 5-6 membered aryl, a 5-6 membered heteroaryl, a C.sub.1-8 alkyl, C.sub.2-8 alkenyl, a C.sub.0-8 alkylsilyl, a R.sub.0 substituted 5-6 membered aryl, a R.sub.0 substituted 5-6 membered heteroaryl, a R.sub.0 substituted C.sub.1-8 alkyl, a R.sub.0 substituted C.sub.2-8 alkenyl, or a R.sub.0 substituted C.sub.0-8 alkylsilyl; [0032] R is selected from: a 5-6 membered aryl, a 5-6 membered heteroaryl, a C.sub.1-8 alkyl, a C.sub.2-8 alkenyl, a C.sub.0-8 alkylsilyl, a R.sub.0 substituted 5-6 membered aryl, a R.sub.0 substituted 5-6 membered heteroaryl, a R.sub.0 substituted C.sub.1-8 alkyl, a R.sub.0 substituted C.sub.2-8 alkenyl, or a R.sub.0 substituted C.sub.0-8 alkylsilyl; [0033] R.sub.0 is selected from: a C.sub.1-6 alkyl, C.sub.1-6 alkoxy or a halogen.

[0034] In one example, X.sub.3 is N; X.sub.1, X.sub.2 and X.sub.4 are CR.sub.1.

[0035] In one example, X.sub.3 is N; X.sub.1, X.sub.2 and X.sub.4 are CH, that is, they are selected from a structure shown in the following general formula:

##STR00011##

[0036] In one example, R.sub.1 is selected from: H, a C.sub.1-6 alkyl, a C.sub.2-6 alkenyl, a R.sub.0 substituted C.sub.1-6 alkyl or a R.sub.0 substituted C.sub.2-6 alkenyl.

[0037] In one example, R is selected from: a 5-6 membered aryl, a 5-6 membered heteroaryl, a C.sub.1-6 alkyl, a C.sub.2-6 alkenyl, a C.sub.0-6 alkylsilyl, a R.sub.0 substituted 5-6 membered aryl, a R.sub.0 substituted 5-6 membered heteroaryl, a R.sub.0 substituted C.sub.1-6 alkyl, a R.sub.0 substituted C.sub.2-6 alkenyl, or a R.sub.0 substituted C.sub.0-6 alkylsilyl.

[0038] In one example, the 5-6 membered heteroaryl is selected from: furyl, thienyl, pyrrolyl, pyrazolyl, triazolyl, thiazolyl, imidazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl or triazinyl.

[0039] In one example, R.sub.0 is selected from: a C.sub.1-4 alkyl or a halogen; further, R.sub.0 is selected from a halogen, and further R.sub.0 is selected from fluorine.

[0040] In one example, R is selected from: phenyl, thienyl, imidazolyl, pyridyl, fluorophenyl, fluorothienyl, fluorimidazolyl, fluoropyridyl, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-methyl-1-propyl, 2-butyl, fluoromethyl, fluoroethyl, fluoro-1-propyl, fluoro-2-propyl, fluoro-1-butyl, fluoro-2-methyl-1-propyl, fluoro-2-butyl, vinyl, propenyl, butenyl, fluorovinyl, fluoropropenyl, fluorobutenyl, trimethylsilyl, triethylsilyl, trifluorosilyl, tri(tnifluoromethyl)dimethylsilyl, di(trifluoromethyl)methylsilyl, or tris(trifluoromethyl)silyl.

[0041] In one example, R is selected from: phenyl, fluorophenyl, imidazolyl, methyl, vinyl, trifluoromethyl or trimethylsilyl.

[0042] In one example, the electrolyte additive is selected from any one of the following compounds:

##STR00012##

[0043] For the preparation of the above electrolyte additives, please refer to CN105121404A.

[0044] An embodiment of the present disclosure provides use of anitrogen-containing five-membered heterocyclic sulfonate with the structure shown in formula (I) as an electrolyte additive:

##STR00013## [0045] in which, groups are as defined above, and will not be repeated here.

[0046] An embodiment of the present disclosure provides use of a nitrogen-containing five-membered heterocyclic sulfonate shown in formula (I) in preparation of an electrolyte:

##STR00014## [0047] in which, groups are as defined above, and will not be repeated here.

[0048] An embodiment of the present disclosure provides an electrolyte, including an additive, where the additive includes a first additive, and the first additive is the electrolyte additive as described above.

[0049] In one example, the above additive further includes a second additive, the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propylene sulfonic lactone, 1,3-propane sulfonic lactone, ethylene sulfate and methylene methanedisulfonate.

[0050] In one example, the electrolyte is a non-aqueous electrolyte.

[0051] In one example, a content of the additive in the electrolyte is 0.01% to 30% by mass percent, further the content of electrolyte additive is 0.01% to 10% by mass percent; in one example, the above electrolyte further includes a lithium salt and a solvent; in one example, a content of the lithium salt in the electrolyte is 5% to 20% by mass percent and a content of the solvent is 50% to 94.9% by mass percent.

[0052] In one example, a content of the first additive in the electrolyte is 0.01% to 10% by mass percent; further the content of the first additive is 0.10% to 10% by mass percent.

[0053] In one example, a content of the second additive in the electrolyte is 0.01% to 5% by mass percent.

[0054] If the content of the first additive is too low, a SEI film formed in the negative electrode is incomplete, and the effect of improving the subsequent cycle of the battery is not good; if the content of the first additive is too high, the ability to reduction to form the film is too strong, and the SEI film formed on the surface of the negative electrode is too thick, which will increase an internal resistance of the battery, and thus have a negative effect on the performance of the battery. Therefore, by controlling the content of the additive in the above range, the stability and the film-forming effect of the electrolyte can be ensured, thereby improving the cycle performance of the battery.

[0055] In one example, in the above electrolyte, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorophosphate, lithium difluoroxalate phosphate, and lithium bis(fluorosulfonyl)imide.

[0056] In one example, in the above electrolyte, the solvent includes a cyclic solvent and/or a linear solvent; where the cyclic solvent is selected from at least one of ethylene carbonate, propylene carbonate, -butyrolactone, phenyl acetate, 1,4-butane sultone and propylene 3,3,3-trifluorocarbonate; the linear solvent is selected from at least one of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl acetate, methyl propyl carbonate, propyl propionate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and methyl 2,2-difluoroethyl carbonate.

[0057] An embodiment of the present prevention provides an energy storage device, including the above electrolyte, which is specifically as described above and will not be repeated here. In one example, the energy storage device is a lithium-ion battery.

[0058] In an example, a positive electrode material of the lithium-ion battery includes one or more of Li.sub.1+a(Ni.sub.xCO.sub.yM.sub.1-x-y)O.sub.2, Li(Ni.sub.pMn.sub.qCo.sub.2-p-q)O.sub.4 and LiM.sub.h(PO.sub.4).sub.m, where 0a0.3, 0x1, 0y1, 0x+y1; 0p2, 0q22, 0<p+q<2; 0<h<5, 0<m<5; M is Fe, Ni, Co, Mn, Al or V.

[0059] In an example, a negative electrode material of the lithium-ion battery includes at least one of a metal lithium, a lithium alloy, a carbon, a silicon-based negative electrode material and a tin-based negative electrode material.

[0060] The above lithium-ion battery can effectively inhibit the rise of acidity and chromaticity of the electrolyte by using the electrolyte including the nitrogen-containing five-membered heterocyclic sulfonate compounds, and the above electrolyte additive has good compatibility with graphite as the negative electrode and they can react on a surface of the electrode to form a film. The alkylated lithium sulfate produced by the decomposition of the electrolyte additive introduces element S into the SEI film, increasing the ionic conductivity and improving the cycle performance of the lithium-ion battery.

[0061] Specific examples are listed below to illustrate the present disclosure, but the present disclosure is not limited to the following examples. In the following examples, the reagents, materials and instruments used can be commercially available unless otherwise specified.

Example 1

[0062] (1) Composition of Electrolyte:

[0063] A structure of an electrolyte additive in the present example is as shown in formula (I1):

##STR00015##

[0064] In the present example, the compound shown in formula (I1) accounts for 0.3% of a weight of the electrolyte; a conventional additive is VC, and VC accounts for 1% of the weight of the electrolyte, a lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; a solvent is a mixture of ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1:2; and the electrolyte of Example 1 was prepared according to a conventional electrolyte preparation method.

[0065] (2) Assembling of Lithium-Ion Battery:

[0066] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is a polyethylene film; and an electrolyte is the electrolyte in Example 1. They were assembled into a soft package battery according to a conventional method.

Example 2

[0067] (1) Composition of Electrolyte:

[0068] A structure of an electrolyte additive in the present example is shown in formula (I3):

##STR00016##

[0069] In the present example, the compound shown in formula (I3) accounts for 0.3% of a weight of the electrolyte; a conventional additive is VC and VC accounts for 1% of the weight of the electrolyte; a lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; a solvent is a mixture of ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1:2; and the electrolyte of Example 2 was prepared according to a conventional electrolyte preparation method.

[0070] (2) Assembling of Lithium-Ion Battery:

[0071] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is a polyethylene film; and an electrolyte is the electrolyte in Example 2. They were assembled into a soft package battery according to a conventional method.

Example 3

[0072] (1) Composition of Electrolyte:

[0073] A structure of an electrolyte additive in the present example is shown in formula (I5):

##STR00017##

[0074] In the present example, the compound shown in formula (I5) accounts for 0.3% of a weight of the electrolyte; a conventional additive is VC and VC accounts for 1% of the weight of the electrolyte; a lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; a solvent is a mixture of ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1:2; and the electrolyte of Example 3 was prepared according to a conventional electrolyte preparation method.

[0075] (2) Assembling of Lithium-Ion Battery:

[0076] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is a polyethylene film; and an electrolyte is the electrolyte in Example 3. They were assembled into a soft package battery according to a conventional method.

Example 4

[0077] (1) Composition of Electrolyte:

[0078] A structure of an electrolyte additive in the present example is shown in formula (I1):

##STR00018##

[0079] In the present example, the compound shown in formula (I1) accounts for 0.5% of a weight of the electrolyte; a conventional additive is VC and VC accounts for 1% of the weight of the electrolyte, a lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; a solvent is a mixture of ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1:2; and the electrolyte of Example 4 was prepared according to a conventional electrolyte preparation method.

[0080] (2) Assembling of Lithium-Ion Battery:

[0081] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is a polyethylene film; and an electrolyte is the electrolyte in Example 4. They were assembled into a soft package battery according to a conventional method.

Example 5

[0082] (1) Composition of Electrolyte:

[0083] A structure of an electrolyte additive in the present example is shown in formula (I1):

##STR00019##

[0084] In the present example, the compound shown in formula (I1) accounts for 10% of a weight of the electrolyte; a conventional additive is VC and VC accounts for 1% of the weight of the electrolyte, a lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; a solvent is a mixture of ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1:2; and the electrolyte of Example 5 was prepared according to a conventional electrolyte preparation method.

[0085] (2) Assembling of Lithium-Ion Battery:

[0086] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is a polyethylene film; and an electrolyte is the electrolyte in Example 5. They were assembled into a soft package battery according to a conventional method.

Example 6

[0087] (1) Composition of Electrolyte:

[0088] A structure of an electrolyte additive in the present example is shown in formula (I1):

##STR00020##

[0089] In the present example, the compound shown in formula (I1) accounts for 0.5% of a weight of the electrolyte; a conventional additive is VC and VC accounts for 1% of the weight of the electrolyte, a lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; a solvent is a mixture of ethylene carbonate, methyl ethyl carbonate and diethyl carbonate at a weight ratio of 3:5:2; and the electrolyte of Example 6 was prepared according to a conventional electrolyte preparation method.

[0090] (2) Assembling of Lithium-Ion Battery:

[0091] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is a polyethylene film; and an electrolyte is the electrolyte in Example 6. They were assembled into a soft package battery according to a conventional method.

Example 7

[0092] (1) Composition of electrolyte:

[0093] A structure of an electrolyte additive in the present example is shown in formula (I1):

##STR00021##

[0094] In the present example, the compound shown in formula (I1) accounts for 0.5% of a weight of the electrolyte; a conventional additive is VC and DTD, where VC and DTD each account for 1% of the weight of the electrolyte, a lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; a solvent is a mixture of ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1:2; and the electrolyte of Example 7 was prepared according to a conventional electrolyte preparation method.

[0095] (2) Assembling of Lithium-Ion Battery:

[0096] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is polyethylene film; and an electrolyte is the electrolyte in Example 7. They were assembled into a soft package battery according to a conventional method.

Example 8

[0097] (1) Composition of Electrolyte:

[0098] A structure of an electrolyte additive in the present example is shown in formula (I1):

##STR00022##

[0099] In the present example, the compound shown in formula (I1) accounts for 0.5% of a weight of the electrolyte; a conventional additive is VC and DTD, where VC and DTD each account for 1% of the weight of the electrolyte, a lithium salt is lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, where the lithium salt and lithium bis(fluorosulfonyl)imide account for 12% and 1% of the weight of the electrolyte, respectively; a solvent is a mixture of ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1:2; and the electrolyte of Example 8 was prepared according to a conventional electrolyte preparation method.

[0100] (2) Assembling of Lithium-Ion Battery:

[0101] A positive electrode material is LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2; a negative electrode material is an artificial graphite; a separator is a polyethylene film; and an electrolyte is the electrolyte in Example 8. They were assembled into a soft package battery according to a conventional method.

Comparative Example 1

[0102] Compared with Example 1, a difference of Comparative Example 1 is that the electrolyte does not include a sulfonate compound.

Comparative Example 2

[0103] Compared with Example 1, a difference of Comparative Example 2 is that the electrolyte additive in Example 1 is replaced with an ethylene sulfate additive that accounts for 1% of the weight of the electrolyte.

Comparative Example 3

[0104] Compared with Example 1, a difference of Comparative Example 3 is that the electrolyte additive of Example 1 is replaced with a triphenyl phosphite additive that accounts for 0.05% of the weight of the electrolyte.

Comparative Example 4

[0105] Compared with Example 7, a difference of Comparative Example 4 is that the electrolyte additive of Example 7 is replaced with a triphenyl phosphite additive that accounts for 0.05% of the weight of the electrolyte.

Comparative Example 5

[0106] Compared with Example 4, a difference of Comparative Example 5 is that the electrolyte additive of Example 4 is replaced with a phenyl benzenesulfonate additive that accounts for 0.5% of the weight of the electrolyte.

[0107] Electrolyte Stability and High-Temperature Performance Tests of Lithium-Ion Battery

[0108] The electrolyte stability and high-temperature performance of the lithium-ion batteries in Examples 1 to 8 and Comparative Examples 1 to 5 were tested. The tests method are as follows:

[0109] Electrolyte stability test: the electrolytes of the lithium-ion batteries as prepared in the above Examples 1 to 8 and Comparative Examples 1 to 5 were each charged in imported sealed aluminum bottles, which were vacuum encapsulated with an aluminum-plastic film. The electrolyte samples were simultaneously placed in a thermostat at a set temperature of 45 C. for storage. The samples were transferred to a glove box for sampling to test the acidity and chromaticity of the electrolytes before storage and after 7 days, 14 days, 30 days and 60 days of storage, respectively. The acidity was tested by a potentiometric titrator with acidity value converted to HF in ppm, and the chromaticity was tested by platinum-cobalt colorimetry in Hazen.

[0110] The test results are shown in Tables 1 and 2:

TABLE-US-00001 TABLE 1 (acidity/ppm) Before Number storage 7 days 14 days 30 days 60 days Example 1 5.5 20.3 25.2 29.8 33.3 Example 2 5.4 19.9 23.4 30.2 35.5 Example 3 6.7 22.7 28.9 32.1 36.0 Example 4 5.4 19.8 24.3 26.9 31.1 Example 5 4.4 16.7 20.3 25.8 28.4 Example 6 7.3 21.3 25.6 27.4 31.9 Example 7 7.5 24.4 30.5 38.9 46.3 Example 8 6.8 23.1 27.9 35.0 42.4 Comparative Example 1 14.4 32.9 36.6 38.0 45.4 Comparative Example 2 15.1 97.5 111.8 126.3 139.0 Comparative Example 3 13.9 28.5 30.2 32.5 39.0 Comparative Example 4 14.6 31.6 41.2 58.6 86.3 Comparative Example 5 14.1 33.2 35.4 39.3 46.7

TABLE-US-00002 TABLE 2 (chrominance/Hazen) Before Number storage 7 days 14 days 30 days 60 days Example 1 10 10 15 35 50 Example 2 10 10 20 40 50 Example 3 10 15 25 40 60 Example 4 10 10 10 20 45 Example 5 10 10 10 20 40 Example 6 10 10 10 20 45 Example 7 10 20 30 40 60 Example 8 10 10 20 40 60 Comparative Example 1 10 20 40 70 90 Comparative Example 2 10 50 80 150 300 Comparative Example 3 10 10 20 40 70 Comparative Example 4 10 20 40 50 100 Comparative Example 5 10 20 50 80 100

[0111] High-temperature cycle performance test of the battery: the lithium-ion batteries prepared by the above Examples 1 to 8 and Comparative Examples 1 to 5 were placed in a thermostat at 45 C., charged to 4.2 V at a constant current of 1 C and a constant voltage, and then discharged to 3.0 V at a constant current of 1 C. The capacity retention rate of the lithium-ion batteries was measured after cycling for 700 cycles.

[0112] The test results are shown in Table 3:

TABLE-US-00003 TABLE 3 Capacity retention rate after cycling at Number 45 C. for 700 cycles Example 1 90.5% Example 2 90.1% Example 3 90.6% Example 4 91.7% Example 5 89.9% Example 6 91.6% Example 7 92.5% Example 8 93.3% Comparative Example 1 86.6% Comparative Example 2 89.5% Comparative Example 3 86.1% Comparative Example 4 89.4% Comparative Example 5 88.9%

[0113] It can be known from Tables 1 to 2 that the acidity and chromaticity of the electrolytes of the lithium-ion batteries in Examples 1 to 8 are lower than those of Comparative Examples 1 to 5 when stored at 45 C. high temperature for 60 days. FIG. 1 shows views of the electrolytes of Comparative Example 1, Comparative Example 2 and Examples 4 and 6 to 8 before and after storage. It can be seen from FIG. 1 that the colors of Examples 4 and 6 to 8 are basically unchanged, but the colors of Comparative Examples 1 and 2 are significantly deepened, especially Comparative Example 2. It shows that the electrolyte additives in Examples 1 to 8 can effectively inhibit the rise of acidity and chromaticity of the electrolyte, and the electrolyte containing the electrolyte additive has enhanced stability at an elevated temperature.

[0114] It can be known from Table 3, the high-temperature cycle performance of the lithium-ion batteries in Examples 1 to 8 is superior to that of Comparative Examples 1 to 5. FIG. 2 is dQ/dV curve diagrams of Comparative Example 1, Comparative Example 2 and Example 4. It can be seen from FIG. 2 that the cycle performance of Example 4 is significantly superior to that of Comparative Examples 1 and 2. It shows that the electrolyte additives in Examples 1 to 8 can form a stable SEI film on the surface of the negative electrode, and thus improve the high-temperature cycle performance of the lithium-ion battery.

[0115] The technical features of the above examples can be arbitrarily combined, and for the sake of brevity of description, not all possible combinations of various technical features in the above examples have been described; however, as long as there is no contradiction in the combinations of these technical features, they shall be considered to be within the scope of the present specification.

[0116] The above examples only describe several embodiments of the present disclosure, and are described in a more specific and detailed manner, but they cannot be understood as a limitation on the patent scope of the present disclosure. It should be pointed out that for a person of ordinary skill in the art, a number of deformations and improvements can be made without departing from the conception of the present disclosure, and they fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure patent shall be subject to the appended claims.