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CN-121983668-A - Electrolyte composition, sodium ion battery electrolyte and sodium ion battery

CN121983668ACN 121983668 ACN121983668 ACN 121983668ACN-121983668-A

Abstract

The invention relates to the field of sodium ion batteries, and discloses an electrolyte composition, sodium ion battery electrolyte and a sodium ion battery. In order to overcome the problem of poor high-temperature cycle performance and storage performance of a sodium ion battery in the prior art, the invention provides an electrolyte composition, which comprises an additive consisting of cyclic carbonate, anhydride and sulfonic acid compounds, so that SEI film and CEI film in the prepared sodium ion battery have better stability, thereby having excellent high-temperature cycle performance and storage performance.

Inventors

  • CHEN GANG
  • ZHAO CHANGHAO
  • HUANG JINMEI
  • MA SHIBING
  • TENG YANMEI
  • SU JINRAN

Assignees

  • 广东海四达钠星技术有限公司

Dates

Publication Date
20260505
Application Date
20241028

Claims (10)

  1. 1. An electrolyte composition is characterized by comprising a film forming additive, wherein the film forming additive comprises cyclic carbonate shown in a formula (1), anhydride shown in a formula (2) and a sulfonic acid compound shown in a formula (3); Formula (1): formula (2): Formula (3): Wherein R 1 、R 2 、R 3 and R 4 are each independently selected from the group consisting of alkyl of H, C 1 -C 6 , alkyl of halo C 1 -C 6 , aryl of C 6 -C 12 , and halogen, and at least one of R 1 、R 2 、R 3 and R 4 is F or alkyl of fluoro C 1 -C 6 ; R 5 、R 6 、R 7 and R 8 are each independently selected from H or-COOR 9 , and at least one of R 5 、R 6 、R 7 and R 8 is-COOR 9 ,R 9 selected from H or C 1 -C 6 alkyl; R 10 and R 11 are each independently selected from H or an alkali metal element; R 12 is selected from the group consisting of alkylene of C 1 -C 6 .
  2. 2. The electrolyte composition according to claim 1, wherein, in the cyclic carbonate represented by formula (1), R 1 、R 2 、R 3 and R 4 are each independently selected from the group consisting of an alkyl group of H, C 1 -C 3 , an alkyl group of fluoro C 1 -C 6 , an aryl group of C 6 -C 10 , and F, and at least one of R 1 、R 2 、R 3 and R 4 is F or an alkyl group of fluoro C 1 -C 6 ; Preferably, the cyclic carbonate represented by formula (1) is selected from at least one of carbonates represented by the following formula (1-1): formula (1-2): formula (1-3): formula (1-4): formula (1-5): Formula (1-6):
  3. 3. The electrolyte composition according to claim 1 or 2, wherein, in the acid anhydride represented by formula (2), R 5 、R 6 、R 7 and R 8 are each independently selected from H or-COOR 9 , and at least one of R 5 、R 6 、R 7 and R 8 is-COOR 9 ,R 9 selected from H, methyl, ethyl or n-propyl; Preferably, the acid anhydride represented by formula (2) is selected from at least one of acid anhydrides represented by the following formulas; formula (2-1): formula (2-2): formula (2-3): formula (2-4):
  4. 4. The electrolyte composition according to any one of claims 1 to 3, wherein, in the sulfonic acid-based compound represented by formula (3), R 10 and R 11 are each independently selected from H or Na, R 12 is selected from -CH 2 -、-CH 2 -CH 2 -、-CH 2 -CH 2 -CH 2 -、-CH(CH 3 )-CH 2 -、-CH 2 -CH(CH 3 )-、-CH 2 -(CH 2 ) 2 -CH 2 -、-C(CH 3 ) 2 -CH 2 - and-CH 2 -C(CH 3 ) 2 -; Preferably, the sulfonic acid compound represented by the formula (3) is at least one selected from sulfonic acid compounds represented by the following formulas; formula (3-1): Formula (3-2): Formula (3-3):
  5. 5. electrolyte composition according to any one of claims 1 to 4, wherein the film-forming additive is used in an amount of 15 to 55wt%, preferably 20 to 35wt%, based on the total mass of the electrolyte composition.
  6. 6. The electrolyte composition according to any one of claims 1 to 5, wherein the weight ratio of the cyclic carbonate represented by formula (1), the acid anhydride represented by formula (2) and the sulfonic acid compound represented by formula (3) in the film-forming additive is 1:0.1 to 5:0.1 to 3, preferably 1:0.2 to 3:0.2 to 1.5.
  7. 7. The electrolyte composition of any one of claims 1-6, wherein the sodium electrolyte composition further comprises a sodium salt selected from one or more of sodium hexafluorophosphate, sodium perchlorate, and sodium tetrafluoroborate; Preferably, the sodium salt is used in an amount of 45 to 85wt%, preferably 65 to 80wt%, based on the total mass of the electrolyte composition.
  8. 8. A sodium ion battery electrolyte comprising the electrolyte composition of any one of claims 1-7.
  9. 9. The sodium ion battery electrolyte according to claim 8, wherein the sodium ion battery electrolyte contains a nonaqueous organic solvent in an amount of 70-90wt% and the electrolyte composition in an amount of 10-30wt%; Preferably, the non-aqueous organic solvent is selected from the group consisting of carbonate compounds; More preferably, the carbonate compound is selected from one or more of methyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, preferably from propylene carbonate and/or ethylmethyl carbonate.
  10. 10. A sodium ion battery, wherein the electrolyte in the sodium ion battery is the sodium ion battery electrolyte as claimed in claim 8 or 9.

Description

Electrolyte composition, sodium ion battery electrolyte and sodium ion battery Technical Field The invention relates to the field of sodium ion batteries, in particular to an electrolyte composition, sodium ion battery electrolyte and a sodium ion battery. Background The lithium ion battery is widely applied to various large fields by virtue of the advantages of high energy density, high working voltage, long cycle life, environmental friendliness and the like. However, with the proliferation of lithium demand, the scarce lithium element will limit further large-scale application of lithium ion batteries. Meanwhile, with the development of terminal application, the energy density of the secondary battery is no longer the only index to be pursued, and the sodium ion battery is favored by the vast researchers by virtue of the advantages of abundant resource reserves, wide distribution, low potential cost and the like, so that the commercialization process of the sodium ion battery is rapidly promoted. The electrolyte is an important component of sodium ion batteries, and the SEI properties including morphology, composition and conductivity in sodium ion batteries have great influence on the electrochemical performance and safety of sodium ion battery systems. 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, the existing sodium ion battery technology often improves high-temperature cycle performance and storage performance by adding a certain film forming agent into electrolyte, but still cannot meet the market demand. Disclosure of Invention The invention aims to solve the problem of poor high-temperature cycle performance and storage performance of a sodium ion battery in the prior art, and provides an electrolyte composition. In order to achieve the above object, the present invention provides an electrolyte composition comprising a film-forming additive comprising a cyclic carbonate represented by formula (1), an acid anhydride represented by formula (2), and a sulfonic acid compound represented by formula (3); Formula (1): formula (2): Formula (3): Wherein R 1、R2、R3 and R 4 are each independently selected from the group consisting of alkyl of H, C 1-C6, alkyl of halo C 1-C6, aryl of C 6-C12, and halogen, and at least one of R 1、R2、R3 and R 4 is F or alkyl of fluoro C 1-C6; R 5、R6、R7 and R 8 are each independently selected from H or from the formula-COOR 9, and at least one of R 5、R6、R7 and R 8 is-COOR 9,R9 selected from H or from C 1-C6 alkyl; R 10 and R 11 are each independently selected from H or an alkali metal element, and R 12 is selected from an alkylene group of C 1-C6. In a second aspect, the invention provides a sodium ion battery electrolyte comprising the electrolyte composition of the first aspect of the invention. According to a third 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 second aspect of the invention. The inventor finds that the cyclic carbonate shown in the formula (1), the anhydride shown in the formula (2) and the sulfonic acid compound shown in the formula (3) can participate in the formation of a negative electrode SEI interface film in the first charging process, thereby being beneficial to increasing the stability of SEI, and meanwhile, the cyclic carbonate can participate in the formation of a positive electrode CEI interface, thereby promoting the formation of a uniform, compact and moderate-thickness CEI film and protecting the positive electrode layered oxide from being corroded by electrolyte. In the invention, cyclic carbonate, sulfonic acid compounds and anhydride are selected as film forming additives, so that a uniform and thinner SEI film can be formed on the surface of a nega