Electrolyte and electrochemical device

Patent metadata

Field	Value
Publication number	US-2020161702-A1
Application number	US-201916406943-A
Country	US
Kind code	A1
Filing date	May 8, 2019
Priority date	Nov 20, 2018
Publication date	May 21, 2020
Grant date	—

Abstract

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.

First claim

1 . An electrolyte, comprising an organic solvent, an additive and a lithium salt, the additive comprising a cyclic borate and a nitrile compound.

2 . The electrolyte of claim 1 , wherein the cyclic borate has the following structure:

wherein:
R 1 is an alkyl group having 1-18 carbon atoms, a cycloalkyl group having 6-18 carbon atoms, an alkoxy group having 1-18 carbon atoms, a cyclic alkoxy group having 3-18 carbon atoms, a borate alkyl group having 3-12 carbon atoms or a cyclic borate alkyl group having 3-12 carbon atoms.

3 . The electrolyte of claim 1 , wherein the cyclic borate is at least one selected from the group consisting of:

4 . The electrolyte of claim 1 , wherein based on the total weight of the electrolyte, the content of the nitrile compound is about 0.05% to about 6%, and the content of the cyclic borate is about 0.01% to about 3%.

5 . 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.

6 . The electrolyte of claim 1 , wherein the nitrile compound is at least one selected from the group consisting of:

7 . The electrolyte of claim 1 , 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.

8 . The electrolyte of claim 1 , wherein the additive further comprises a fluorosulfonate, based on the total weight of the electrolyte, the content of the fluorosulfonate being about 0.01% to about 5%.

9 . The electrolyte 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.

10 . The electrolyte of claim 8 , wherein the fluorosulfonate is at least one selected from the group consisting of:

11 . 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.

12 . 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.

13 . The electrochemical device of claim 12 , wherein the cyclic borate has the following structure:

wherein:
R 1 is an alkyl group having 1-18 carbon atoms, a cycloalkyl group having 6-18 carbon atoms, an alkoxy group having 1-18 carbon atoms, a cyclic alkoxy group having 3-18 carbon atoms, a borate alkyl group having 3-12 carbon atoms or a cyclic borate alkyl group having 3-12 carbon atoms, based on the total weight of the electrolyte, the content of the nitrile compound is about 0.05% to about 6%, and the content of the cyclic borate is about 0.01% to about 3%.

14 . The electrochemical device of claim 12 , wherein the cyclic borate is at least one selected from the group consisting of:

15 . The electrochemical device of claim 12 , 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.

16 . The electrochemical device of claim 12 , wherein the nitrile compound is at least one selected from the group consisting of:

17 . The electrochemical device of claim 12 , wherein the additive further comprises a fluorosulfonate, 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;
based on the total weight of the electrolyte, the content of the fluorosulfonate being about 0.01% to about 5%.

18 . The electrochemical device of claim 17 , wherein the fluorosulfonate is at least one selected from the group consisting of:

19 . The electrochemical device of claim 12 , 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.

20 . An electro

Assignees

• Ningde Amperex Technology Ltd

Inventors

• Ma Juan
• Zhang Shuirong
• Liu Junfei
• Tang Chao

Classifications

• H01M10/0567 Primary

  characterised by the additives · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M2300/0025

  Organic electrolyte · CPC title

• H01M10/0569

  characterised by the solvents · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title