CN-119542547-B - Sodium salt composition, sodium ion battery electrolyte, application of sodium ion battery electrolyte and sodium ion battery

Abstract

The invention belongs to the technical field of sodium ion batteries, and particularly relates to a sodium salt composition, sodium ion battery electrolyte, application of the sodium ion battery electrolyte and a sodium ion battery. The sodium salt composition provided by the invention comprises any five or more of sodium bistrifluoromethane sulfonyl imide, sodium hexafluorophosphate, sodium difluorooxalate borate, sodium fluoroborate, sodium nitrate, sodium perchlorate and sodium difluorophosphate, and the solvation configuration of the sodium ion battery electrolyte prepared by the sodium salt composition is an aggregate with multipolar solvation shell layers, so that an inorganic-rich positive electrode surface solid electrolyte interface film (CEI) and a negative electrode surface solid electrolyte interface film (SEI) can be formed, the positive electrode and the negative electrode are effectively protected, and the cycle stability and the multiplying power performance of the sodium ion battery are improved.

Inventors

• HU JIANGTAO
• ZHANG QIANLING
• He Xuanlong
• LI LIEWU
• WANG DAI
• DENG JIAOJIAO

Assignees

• 深圳大学

Dates

Publication Date

20260512

Application Date

20241212

Claims (6)

1. 1. A sodium ion battery electrolyte, which is characterized by comprising a sodium salt composition, an organic solvent and an additive; The sodium salt composition comprises NaTFSI, naPF 6 、NaDFOB、NaBF 4 and NaNO 3 , naTFSI, naClO 4 、NaDFOB、NaBF 4 and NaNO 3 , or NaDFP, naClO 4 、NaDFOB、NaBF 4 and NaNO 3 , wherein the amounts of substances of sodium salts in the sodium salt composition are the same; the solvated configuration of the sodium ion battery electrolyte is an aggregate with multipolar solvated shell layers; The concentration of the sodium salt composition in the sodium ion battery electrolyte is 0.5mol/L; the volume percentage content of the aggregate in the sodium ion battery electrolyte is 70-85%; The organic solvent is tetrahydrofuran; The additive is ethylene carbonate.
2. 2. The sodium ion battery electrolyte according to claim 1, wherein the mass concentration of the additive in the sodium ion battery electrolyte is 3-5%.
3. 3. Use of the electrolyte of a sodium ion battery according to claim 1 or 2 in a sodium ion battery.
4. 4. A sodium ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte is the sodium ion battery electrolyte of claim 1 or 2.
5. 5. The sodium ion battery of claim 4, wherein the active material of the positive electrode comprises a layered oxide, a prussian blue-based compound, or a polyanion-based compound.
6. 6. The sodium ion battery of claim 4, wherein the negative electrode comprises hard carbon, sodium metal, or sodium titanium phosphate.

Description

Sodium salt composition, sodium ion battery electrolyte, application of sodium ion battery electrolyte and sodium ion battery Technical Field The invention belongs to the technical field of sodium ion batteries, and particularly relates to a sodium salt composition, sodium ion battery electrolyte, application of the sodium ion battery electrolyte and a sodium ion battery. Background With the continued development of human society, how to develop and utilize energy efficiently and safely becomes a significant challenge for humans. The utilization of clean energy sources such as solar, wind and tidal energy requires the development of large scale energy storage technologies. The lithium ion battery is the preferred energy storage equipment in the fields of portable electronic equipment, electric vehicles and the like at present by virtue of the advantages of high energy density, low self-discharge, long cycle life and the like. However, lithium ion batteries also face the problem of lithium resource starvation in applications facing large-scale energy storage. The sodium ion battery and the lithium ion battery have similar working principles, sodium resources on the earth are very rich, and meanwhile, the sodium ion battery has the advantages of low cost, good cycle life and the like, and is a powerful competitor in the field of large-scale energy storage. However, the high degree of instability of the electrode/electrolyte interface during cycling severely hampers the development of sodium ion batteries. In particular, unstable positive electrode electrolyte interfaces (CEI) can lead to continuous electrolyte side reactions, transition metal leaching and rapid capacity fade, thereby reducing the cycling stability and rate performance of sodium ion batteries. Disclosure of Invention In view of the above, the present invention aims to provide a sodium salt composition, a sodium ion battery electrolyte, applications thereof, and a sodium ion battery, wherein the electrolyte prepared from the sodium salt composition is an aggregate with multipolar solvated shell layers, and can form a positive electrode surface solid electrolyte interface film (CEI) and a negative electrode surface solid electrolyte interface film (SEI) which are rich in inorganic matters, so that the positive electrode and the negative electrode are effectively protected, and the cycle stability and the rate capability of the sodium ion battery are improved. In order to achieve the above object, the present invention provides the following technical solutions: The invention provides a sodium salt composition, which comprises any five or more of sodium bistrifluoromethane sulfonyl imide, sodium hexafluorophosphate, sodium difluorooxalate borate, sodium fluoroborate, sodium nitrate, sodium perchlorate and sodium difluorophosphate. Preferably, the amount of the substance of each sodium salt in the sodium salt composition is the same. The invention also provides a sodium ion battery electrolyte, which comprises a sodium salt composition, an organic solvent and an additive; the sodium salt composition is the sodium salt composition according to the technical scheme; the solvated configuration of the sodium ion battery electrolyte is an aggregate with multipolar solvated shell layers; The concentration of the sodium salt composition in the sodium ion battery electrolyte is 0.5-0.8 mol/L; the volume percentage content of the aggregate in the sodium ion battery electrolyte is 70-85%. Preferably, the organic solvent comprises one or more of tetrahydrofuran, ethylene glycol dimethyl ether and dioxolane. Preferably, the additive comprises one or more of ethylene carbonate, vinylene carbonate, propylene sulfite and ethylene sulfate. Preferably, the mass concentration of the additive in the sodium ion battery electrolyte is 3-5%. The invention also provides application of the sodium ion battery electrolyte in sodium ion batteries. The invention also provides a sodium ion battery, which comprises an anode, a cathode, a diaphragm and electrolyte, wherein the electrolyte is the sodium ion battery electrolyte according to the technical scheme. Preferably, the active material of the positive electrode includes a layered oxide, a Prussian blue compound, or a polyanion compound. Preferably, the negative electrode includes hard carbon, sodium metal, or sodium titanium phosphate. The invention provides a sodium salt composition, which comprises any five or more of sodium bistrifluoromethane sulfonyl imide, sodium hexafluorophosphate, sodium difluorooxalate borate, sodium fluoroborate, sodium nitrate, sodium perchlorate and sodium difluorophosphate. In the electrolyte, organic solvent molecules are arranged around sodium ions to form solvated shell layers, the solubility of each sodium salt in the sodium salt composition provided by the invention is different, the dissociation difficulty and the dissociation difficulty in the organic solvent are also different, and t