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CN-122000457-A - Electrolyte and sodium ion battery

CN122000457ACN 122000457 ACN122000457 ACN 122000457ACN-122000457-A

Abstract

The application provides electrolyte and a sodium ion battery, wherein the electrolyte comprises sodium salt and a first additive, the sodium salt comprises sodium bis (fluorosulfonyl) imide, and the first additive has a structure shown in formula 1: Wherein m represents an arbitrary integer of 1 to 12, R 1 、R 2 and R 3 are each independently at least one of C 1 ～C 8 alkyl, C 1 ～C 8 alkoxy, C 2 ～C 8 alkenyl or C 2 ～C 8 alkynyl, and one or both of R 1 、R 2 and R 3 are C 1 ～C 8 alkoxy. The electrolyte provided by the application can effectively improve the working voltage and SEI film stability, and further improve the high-temperature storage performance, the high-temperature and normal-temperature cycle performance, the low-temperature discharge performance and the low-impedance characteristic of the sodium ion battery.

Inventors

  • QIN TAO
  • FAN CHAOJUN
  • FAN WEIZHEN
  • SHI LITAO

Assignees

  • 广州天赐高新材料股份有限公司
  • 九江天赐高新材料有限公司

Dates

Publication Date
20260508
Application Date
20241106

Claims (11)

  1. 1. An electrolyte is characterized by comprising sodium salt and a first additive; The sodium salt comprises sodium bis-fluorosulfonyl imide; the first additive has a structure as shown in formula 1: Wherein m represents an arbitrary integer of 1 to 12, R 1 、R 2 and R 3 are each independently at least one of C 1 ～C 8 alkyl, C 1 ～C 8 alkoxy, C 2 ～C 8 alkenyl or C 2 ～C 8 alkynyl, and one or both of R 1 、R 2 and R 3 are C 1 ～C 8 alkoxy.
  2. 2. The electrolyte of claim 1, wherein m represents any integer of 1 to 6, R 1 、R 2 and R 3 are each independently at least one of C 1 ～C 4 alkyl, C 1 ～C 4 alkoxy, C 2 ～C 4 alkenyl, or C 2 ～C 4 alkynyl, and one or both of R 1 、R 2 and R 3 are C 1 ～C 4 alkoxy.
  3. 3. The electrolyte additive according to claim 1 or 2, wherein the first additive comprises at least one of compounds represented by formulae 1-1 to 1-8:
  4. 4. the electrolyte of claim 1 wherein the sodium salt further comprises sodium hexafluorophosphate.
  5. 5. The electrolyte of claim 1, further comprising a second additive, wherein the second additive comprises sulfonic acid groups.
  6. 6. The electrolyte of claim 5 wherein the second additive comprises a sultone-based compound.
  7. 7. The electrolyte of claim 5 or 6 wherein the second additive comprises at least one of 1, 3-propane sultone, propenyl-1, 3-sultone, 2, 4-butane sultone, 1,3, 2-dioxathiolane-2, 2-dioxide, 5-methyl oxathiolane 2, 2-dioxide, methylene methane disulfonate.
  8. 8. The electrolyte according to any one of claims 1 to 3, wherein the mass ratio of the sodium bis-fluorosulfonyl imide to the first additive is (10 to 50): 1; And/or, based on the total mass of the electrolyte, the content of the sodium bis (fluorosulfonyl) imide is 0.5% -8%; and/or the content of the first additive is 0.01% -1% based on the total mass of the electrolyte.
  9. 9. The electrolyte according to any one of claims 5 to 7, wherein a mass ratio of the sodium bis-fluorosulfonyl imide to the second additive is (1 to 10): 1; And/or the content of the second additive is 0.5% -4% based on the total mass of the electrolyte.
  10. 10. The electrolyte according to claim 4, wherein the mass ratio of the sodium difluorosulfimide to the sodium hexafluorophosphate is 1 (1-10); And/or, the content of the sodium hexafluorophosphate is 2% -18% based on the total mass of the electrolyte.
  11. 11. A sodium ion battery characterized by comprising a positive electrode plate and the electrolyte of any one of claims 1-10; The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side surface of the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may include at least one of the following materials: Na x MO 2 , wherein M comprises at least one of Ti, V, mn, co, ni, fe, zn, V, zr, ce, cr, cu, 0< x≤1; NaFePO 4 、Na 3 V 2 (PO 4 ) 3 、Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 )、NaM'PO 4 F And at least one of Na 3 (VO y ) 2 (PO 4 ) 2 F 3-2y , wherein M' is at least one of V, fe, mn and Ni, and y is more than or equal to 0 and less than or equal to 1; Na a Me b Me' c (CN) 6 , wherein Me and Me' each independently comprise at least one of Ni, cu, fe, mn, co, zn, 0<a≤2, 0< b <1,0< c <1.

Description

Electrolyte and sodium ion battery Technical Field The application relates to the field of material preparation, in particular to electrolyte and a sodium ion battery. Background Sodium and lithium are both alkali metal elements with similar chemical properties and fields of application. The rise of the price of lithium salt limits the development of lithium ion batteries, compared with lithium resources, the sodium resources have rich content in the crust, are simpler to mine and utilize and lower in price, and have the advantages of 1) good low-temperature performance, capability of being used in alpine regions, 2) better safety performance than ternary lithium batteries and ferric phosphate lithium batteries, 3) environmental friendliness and compliance with sustainable development strategies. Therefore, sodium ion batteries are promising alternatives to lithium ion batteries. However, the sodium ion battery has short plates with low energy density, poor cycle stability and the like, and has a certain influence on the large-scale application. Thus, increasing the operating voltage is critical to the increase in energy density and the performance of sodium ion batteries. The electrolyte acts as an ionic conductor to regulate electrochemical behavior and stabilize the interface and electrode between them, affecting the performance of the sodium ion battery. The conventional electrolyte has poor thermal stability, and the surface is easy to generate serious oxidative decomposition when the voltage exceeds 4.2V, so that the capacity and the cycle performance are deteriorated. Disclosure of Invention The present application aims to solve at least one of the technical problems in the related art to some extent. Therefore, the electrolyte and the sodium ion battery provided by the application can effectively improve the working voltage and SEI film stability, and further improve the high-temperature storage performance, the high-temperature and normal-temperature cycle performance, the low-temperature discharge performance and the low-impedance characteristic of the sodium ion battery, and particularly have excellent performance under high-pressure conditions. The first aspect of the application provides an electrolyte comprising a sodium salt and a first additive; The sodium salt comprises sodium bis-fluorosulfonyl imide; the first additive has a structure as shown in formula 1: Wherein m represents an arbitrary integer of 1 to 12, R 1、R2 and R 3 are each independently at least one of C 1～C8 alkyl, C 1～C8 alkoxy, C 2～C8 alkenyl or C 2～C8 alkynyl, and one or both of R 1、R2 and R 3 are C 1～C8 alkoxy. According to the electrolyte provided by the application, the sodium bis (fluorosulfonyl) imide and the first additive have synergistic effect, so that a good interfacial film can be formed on the surface of an electrode material, the working voltage is improved, the impedance increase under the conditions of low temperature and high temperature is inhibited, and the high-temperature storage performance, the high-temperature and normal-temperature cycle performance, the low-temperature discharge performance and the low-impedance characteristic of the sodium ion battery are improved, and the electrolyte has excellent performance especially under the high-pressure condition. According to an embodiment of the present application, m represents an arbitrary integer of 1 to 6, R 1、R2 and R 3 are each independently at least one of C 1～C4 alkyl, C 1～C4 alkoxy, C 2～C4 alkenyl or C 2～C4 alkynyl, and one or both of R 1、R2 and R 3 are C 1～C4 alkoxy. According to an embodiment of the present application, the first additive includes at least one of compounds represented by formulas 1-1 to 1-8: According to an embodiment of the application, the sodium salt further comprises sodium hexafluorophosphate. According to an embodiment of the application, the electrolyte further comprises a second additive comprising sulfonic acid groups. According to an embodiment of the application, the second additive comprises a sultone-based compound. According to an embodiment of the application, the second additive comprises at least one of 1, 3-propane sultone, propenyl-1, 3-sultone, 2, 4-butane sultone, 1,3, 2-dioxathiolane-2, 2-dioxide, 5-methyl oxathiolane 2, 2-dioxide, methylene methane disulfonate. According to the embodiment of the application, the mass ratio of the sodium bis (fluorosulfonyl) imide to the first additive is (10-50): 1; And/or, based on the total mass of the electrolyte, the content of the sodium bis (fluorosulfonyl) imide is 0.5% -8%; and/or the content of the first additive is 0.01% -1% based on the total mass of the electrolyte. According to the embodiment of the application, the mass ratio of the sodium bis (fluorosulfonyl) imide to the second additive is (1-10): 1; And/or the content of the second additive is 0.5% -4% based on the total mass of the electrolyte. According to the embodiment of the application, the mass rat