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CN-122000461-A - Electrolyte for sodium ion battery and sodium ion battery

CN122000461ACN 122000461 ACN122000461 ACN 122000461ACN-122000461-A

Abstract

The invention relates to the field of sodium ion batteries, and discloses sodium ion battery electrolyte and a sodium ion battery. According to the sodium ion battery electrode solution, through the synergistic effect of the sodium salt in the required functional additive and the film forming additive, a compact SEI film can be formed, and the prepared sodium ion battery has excellent cycle performance and electrochemical performance.

Inventors

  • CHEN GANG
  • HU HEXIANG
  • TENG YANMEI
  • MA SHIBING

Assignees

  • 广东海四达钠星技术有限公司

Dates

Publication Date
20260508
Application Date
20241031

Claims (10)

  1. 1. A sodium ion battery electrolyte is characterized by comprising a functional additive and optionally a solvent, wherein the functional additive comprises sodium salt and a film-forming additive, the film-forming additive comprises an anhydride compound and cyclic carbonate shown in a formula (1), the anhydride compound is at least one of diethanol anhydride, succinic anhydride and maleic anhydride, and the content mass ratio of the anhydride compound to the cyclic carbonate is 1:1-5; Formula (1): In formula (1), each R 1 、R 2 is independently selected from the group consisting of alkyl groups of H, C 1 -C 6 .
  2. 2. The sodium ion battery electrolyte according to claim 1, wherein the content mass ratio of the acid anhydride compound to the cyclic carbonate is 1:2-3.
  3. 3. The sodium ion battery electrolyte according to claim 1 or 2, wherein, in formula (1), each R 1 、R 2 is independently selected from alkyl groups of H, C 1 -C 4 ; preferably, each R 1 、R 2 is independently selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl.
  4. 4. The sodium ion battery electrolyte according to any one of claims 1 to 3, wherein the cyclic carbonate represented by formula (1) is selected from at least one of the following compounds; In the formula (1), R 1 is H, R 2 and H is a compound (1); In the formula (1), R 1 is H, R 2 and is methyl; In the formula (1), R 1 is H, R 2 and is ethyl; In the formula (1), R 1 is H, R 2 and n-propyl is a compound (4).
  5. 5. Sodium ion battery electrolyte according to any of claims 1-4, wherein the film forming additive is present in an amount of 1-15wt%, preferably 5-10wt%, based on the total mass of the functional additive.
  6. 6. The sodium ion battery electrolyte of any one of claims 1-5, wherein the sodium salt is selected from one or more of sodium hexafluorophosphate, sodium perchlorate, and sodium tetrafluoroborate.
  7. 7. The sodium ion battery electrolyte according to claim 6, wherein the sodium salt is present in an amount of 85-99wt%, preferably 90-95wt%, based on the total mass of the functional additive.
  8. 8. The sodium ion battery electrolyte according to any one of claims 1 to 7, wherein the sodium ion battery electrolyte further comprises a nonaqueous organic solvent as the solvent, the nonaqueous organic solvent is contained in an amount of 60 to 90wt% and the functional additive is contained in an amount of 10 to 40wt% based on the total mass of the sodium ion battery electrolyte.
  9. 9. The sodium ion battery electrolyte of claim 8, wherein the nonaqueous organic solvent is selected from one or more of methyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methylethyl carbonate; preferably, the non-aqueous organic solvent is selected from propylene carbonate and/or ethylmethyl carbonate.
  10. 10. A sodium ion battery in which the electrolyte is a sodium ion battery electrolyte as claimed in any one of claims 1 to 9.

Description

Electrolyte for sodium ion battery and sodium ion battery Technical Field The invention relates to the field of sodium ion batteries, in particular to sodium ion battery electrolyte and a sodium ion battery. Background The electrolyte of the sodium ion battery is one of important components of the sodium ion battery, and the electrochemical performance and the safety of the battery can be improved by optimizing the composition and the structure of the electrolyte, exploring novel solvents and additives, improving the compatibility of the electrolyte and electrode materials and the like. The high-concentration electrolyte has a wider working voltage range, a wider liquid temperature window and lower flammability, can form a uniform SEI film with a protective effect, and simultaneously inhibits the growth of sodium dendrites, and the properties provide conditions for developing a high-performance battery. Research progress on sodium ion battery electrolytes will provide important support for its commercial applications. The properties of the SEI film in the sodium ion battery, including morphology, composition and conductivity, have great influence on the electrochemical performance and safety of a sodium ion battery system. Specifically, sodium ions in the positive electrode material of the battery are deintercalated in the charging process of the sodium ion battery, and are embedded into the carbon negative electrode through electrolyte. The SEI film formed in the initial charging process can prevent electrolyte from being further decomposed on the surface of the carbon negative electrode, plays a role of a sodium ion conductor and only allows sodium ions to pass through. However, during the subsequent charge and discharge cycles of the sodium ion battery, the electrode may be changed to cause rupture of the SEI film, which may cause the negative electrode to be exposed to the electrolyte again and continuously react with the electrolyte, and gas is generated while the electrolyte is consumed, resulting in an increase in the internal pressure of the sodium ion battery, reducing the cycle life of the battery. Particularly, when the battery is stored or charged and recycled under high temperature conditions, the volume change of the electrode is more obvious, and the SEI film is more easily broken, so that the electrochemical performance of the sodium ion battery is more obviously reduced under the high temperature conditions. Currently, existing sodium ion battery technology often improves cycle performance and electrochemical performance by adding certain film forming agents to the electrolyte, but still cannot meet the market demands. Disclosure of Invention The invention aims to solve the problems of poor cycle performance and electrochemical performance of a sodium ion battery in the prior art, and provides a sodium ion battery electrolyte and a sodium ion battery, wherein the battery has excellent cycle performance and electrochemical performance. In order to achieve the above purpose, the invention provides a sodium ion battery electrolyte, which comprises a functional additive and optionally a solvent, wherein the functional additive comprises sodium salt and a film-forming additive, the film-forming additive comprises an anhydride compound and cyclic carbonate shown in a formula (1), the anhydride compound is at least one of diethanol anhydride, succinic anhydride and maleic anhydride, and the content mass ratio of the anhydride compound to the cyclic carbonate is 1:1-5; Formula (1): In formula (1), each R 1、R2 is independently selected from the group consisting of alkyl groups of H, C 1-C6. According to a second aspect of the invention, there is provided a sodium ion battery, the electrolyte in the sodium ion battery being the electrolyte of the sodium ion battery according to the first aspect of the invention. By adopting the technical scheme, through the synergistic effect of the sodium salt in the functional additive and the film forming additive, a compact SEI film can be formed, and the prepared sodium ion battery has excellent cycle performance and electrochemical performance. Detailed Description The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. In the present invention, the alkyl group of C 1-C6 means a straight-chain or branched alkyl group having 1 to 6 carbon atoms, and includes, but is not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl and isohexyl. The invention pro