Electrolyte and electrochemical device
The present application relates to an electrolyte and an electrochemical device. The electrolyte includes an organic solvent, an additive and a lithium salt, the additive including a cyclic borate and a nitrile compound. The electrolyte of the present application has good stability at a high working voltage. In another embodiment of the present application, the combination of the electrolyte and an anode having a high compacted density provides a high energy density for the electrochemical device, and improves the storage, floating charge and dynamicperformance of the electrochemical device.
1. An electrolyte, comprising an organic solvent, an additive and a lithium salt, the additive comprising a cyclic borate and a nitrile compound, wherein the cyclic borate has the following structure:
wherein the organic solvent comprises a carboxylate having the following structure:
wherein R 4 and R 5 are each independently an alkyl group having 1-5 carbon atoms, and
wherein the carboxylate has a content of 10%-30%,
wherein the additive further comprises a fluorosulfonate, based on a total weight of the electrolyte, a content of the fluorosulfonate being about 0.01% to about 5%.
2. The electrolyte of claim 1 , wherein based on the total weight of the electrolyte, a content of the nitrile compound is about 0.05% to about 6%, and a content of the cyclic borate is about 0.01% to about 3%.
3. The electrolyte of claim 1 , wherein the nitrile compound has the following structure:
wherein:
A is selected from a chain alkyl group having 1-6 carbon atoms, a cycloalkyl group having 3-12 carbon atoms, an alkylene group having 2-6 carbon atoms or a cyclic alkylene group having 6-12 carbon atoms;
R 2 and R 3 are each independently selected from a hydrogen atom, a cyano group, a nitrile group having 1-5 carbon atoms or an alkyl group having 1-8 carbon atoms;
X 1 , X 2 and X 3 are each independently selected from —CH 2 —, —O—, —OCH 2 —, —OCH 2 CH 2 CH 2 —, —OCH 2 CH 2 —, —CHF— or —CF 2 —; and
n 1 , n 2 and n 3 are each independently an integer selected from 0-10.
4. The electrolyte of claim 1 , wherein the nitrile compound is at least one selected from the group consisting of:
5. The electrolyte of claim 1 , wherein the fluorosulfonate has the following structure:
wherein:
R 6 and R 7 are each independently selected from an alkyl group having 2-20 carbon atoms, a fluoroalkyl group having 2-20 carbon atoms, an alkoxy group having 2-10 carbon atoms, a fluoroalkoxy group having 2-10 carbon atoms, an alkenyl group having 2-20 carbon atoms or a fluoroalkenyl group having 2-20 carbon atoms.
6. The electrolyte of claim 1 , wherein the fluorosulfonate is at least one selected from the group consisting of:
7. The electrolyte of claim 1 , wherein the additive further comprising at least one other film-forming additive selected from the group consisting of fluoroethylene carbonate, vinylene carbonate, 1,3-propane sultone, 1,3,2-Dioxathiolane 2,2-dioxide, methylene methanedisulfonate and lithium bis(oxalate)borate.
8. An electrochemical device, comprising:
a cathode;
an anode;
a separator; and
an electrolyte,
wherein the anode has a compacted density of not less than about 1.75 g/cm 3 , and
wherein the electrolyte comprises an organic solvent, an additive and a lithium salt, the additive comprising a cyclic borate and a nitrile compound, wherein the cyclic borate has the following structure:
wherein the organic solvent comprises a carboxylate having the following structure:
wherein R 4 and R 5 are each independently an alkyl group having 1-5 carbon atoms, and
wherein the carboxylate has a content of 10%-30%,
wherein the additive further comprises a fluorosulfonate, based on a total weight of the electrolyte, a content of the fluorosulfonate being about 0.01% to about 5%.
9. The electrochemical device of claim 8 , wherein the nitrile compound has the following structure:
wherein:
A is selected from a chain alkyl group having 1-6 carbon atoms, a cycloalkyl group having 3-12 carbon atoms, an alkylene group having 2-6 carbon atoms or a cyclic alkylene group having 6-12 carbon atoms;
R 2 and R 3 are each independently selected from a hydrogen atom, a cyano group, a nitrile group having 1-5 carbon atoms or an alkyl group having 1-8 carbon atoms;
X 1 , X 2 and X 3 are each independently selected from —CH 2 —, —O—, —OCH 2 —, —OCH 2 CH 2 CH 2 —, —OCH 2 CH 2 —, —CHF— or —CF 2 —; and
n 1 , n 2 and n 3 are each independently an integer selected from 0-10.
10. The electrochemical device of claim 8 , wherein the nitrile compound is at least one selected from the group consisting of:
11. The electrochemical device of claim 8 , wherein the fluorosulfonate has the following structure:
wherein:
R 6 and R 7 are each independently selected from an alkyl group having 2-20 carbon atoms, a fluoroalkyl group having 2-20 carbon atoms, an alkoxy group having 2-10 carbon atoms, a fluoroalkoxy group having 2-10 carbon atoms, an alkenyl group having 2-20 carbon atoms or a fluoroalkenyl group having 2-20 carbon atoms.
12. The electrochemical device of claim 11 , wherein the fluorosulfonate is at least one selected from the group consisting of:
13. The electrochemical device of claim 8 , wherein the additive further comprising at least one other film-forming additive selected from the group consisting of fluoroethylene carbonate, vinylene carbonate, 1,3-propane sultone, 1,3,2-Dioxathiolane 2,2-dioxide, methylene methanedisulfonate and lithium bis(oxalate)borate.
14. An electronic device, comprising the electrochemical device of claim 8 .