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CN-122000443-A - Sulfide solid electrolyte and preparation method and application thereof

CN122000443ACN 122000443 ACN122000443 ACN 122000443ACN-122000443-A

Abstract

The invention belongs to the technical field of lithium ion batteries, and relates to a sulfide solid electrolyte, a preparation method and application thereof. The sulfide solid electrolyte comprises a sulfide solid electrolyte matrix material which is lithium tin sulfur and is phosphorus-free, and Sr element, B element and O element which are doped in the sulfide solid electrolyte matrix material which is lithium tin sulfur and is phosphorus-free. The invention carries out the co-doping of Sr element, B element and O element on the solid electrolyte matrix material of sulfide which is lithium tin sulfur and has no phosphorus, improves the structural stability and ionic conductivity of the material, and further improves the air stability.

Inventors

  • Request for anonymity

Assignees

  • 瑞固(衢州)新材料科技有限公司

Dates

Publication Date
20260508
Application Date
20260211

Claims (10)

  1. 1. A sulfide solid state electrolyte, characterized in that the sulfide solid state electrolyte comprises a sulfide solid state electrolyte matrix material of lithium tin sulfur and no phosphorus, and Sr element, B element, and O element doped in the sulfide solid state electrolyte matrix material of lithium tin sulfur and no phosphorus.
  2. 2. The sulfide solid state electrolyte of claim 1, wherein the sulfide solid state electrolyte has a chemical formula of Li x Sr y B z Sn a O b S c , wherein 0< x <4,0< y <1,0< z < 0.2,0< a <1,0< b <1,0< c <4; Preferably, in Li x Sr y B z Sn a O b S c , 0< y≤0.3.
  3. 3. Sulfide solid state electrolyte according to claim 1 or 2, characterized in that the sulfide solid state electrolyte base material has a coating layer including boric acid on the surface in addition to co-doping of Sr element, B element and O element.
  4. 4. The sulfide solid state electrolyte according to claim 1 or 2, characterized in that the sulfide solid state electrolyte base material has a coating layer whose raw material includes boric acid, in addition to co-doping Sr element, B element, and O element; preferably, when the raw material of the coating layer includes boric acid, the material of the coating layer includes lithium boron oxide, and the boron element in the sulfide solid electrolyte matrix material includes lithium boron oxide; Preferably, the lithium boron oxide comprises LiBO 2 and/or Li 2 B 4 O 7 .
  5. 5. A method for producing the sulfide solid state electrolyte as claimed in any one of claims 1 to 4, characterized by comprising the steps of: Mixing and sintering the preparation raw materials to obtain the sulfide solid electrolyte; wherein the raw materials in the preparation raw materials provide a lithium source, a strontium source, a tin source, a sulfur source and a boron source, and the boron source comprises an oxygen-containing boron source.
  6. 6. The method of claim 5, wherein the strontium source, the lithium source, and the tin source in the starting materials are each independently selected from the corresponding sulfides; Preferably, the oxygen-containing boron source comprises lithium metaborate and/or lithium tetraborate.
  7. 7. The method of producing according to claim 5 or 6, wherein the method of mixing comprises mechanical grinding, the mechanical grinding comprising sequentially performing coarse grinding and fine grinding; Preferably, the rotation speed of the rough grinding is 100 rpm-200 rpm, and the time of the rough grinding is 1 h-10 h; the rotating speed of the fine grinding is 400-600 rpm, and the fine grinding time is 15-30 h; preferably, the sintering is performed in a protective atmosphere, the sintering temperature is more than or equal to 400 ℃, and the sintering time is 1-10 h.
  8. 8. The method according to claim 5, wherein the sintered product is subjected to a coating treatment, and the coated raw material comprises boric acid; preferably, the mass ratio of the boric acid to the sintered product is 1 (50-200); Preferably, the coating method comprises a ball milling method or a deposition method; Preferably, the coating treatment comprises the steps of mixing a sintered product with boric acid in a liquid phase, carrying out ball milling coating, and drying after ball milling coating to obtain a sulfide solid electrolyte with a boric acid coating layer; Preferably, the ball-milled and coated materials are subjected to spray drying and heat treatment to obtain sulfide solid electrolyte with a lithium boron oxide coating layer; preferably, the heat treatment is performed in a protective atmosphere, the temperature of the heat treatment is 200-600 ℃, and the time of the heat treatment is 8-16 h.
  9. 9. An electrochemical device comprising the sulfide solid state electrolyte according to any one of claims 1 to 4 or the sulfide solid state electrolyte produced by the production method according to any one of claims 5 to 8.
  10. 10. The electrochemical device of claim 9, wherein the electrochemical device comprises a solid state lithium ion battery and/or a liquid state lithium ion battery.

Description

Sulfide solid electrolyte and preparation method and application thereof Technical Field The invention belongs to the technical field of lithium ion batteries, and relates to a sulfide solid electrolyte, a preparation method and application thereof. Background In the research and development process of a new generation of high-safety and high-energy-density lithium battery, the breakthrough of the solid electrolyte is certainly a core link. Among them, sulfide solid electrolyte is recognized as one of the solid electrolyte materials with the most commercialized potential by virtue of its remarkable advantages of ultra-high ionic conductivity (part of system room temperature ionic conductivity has exceeded that of conventional liquid electrolytes), good interfacial compatibility, and a wide electrochemical stability window. However, the deadly short plate, namely extremely poor air stability, becomes a 'neck clamping' problem which restricts the mass production and practical application of the short plate. Most sulfide electrolytes can react with moisture and oxygen in the air rapidly after being exposed to the air, so that the ionic conductivity of the sulfide electrolytes is reduced rapidly, corrosive H 2 S gas can be generated, and the safety of equipment and operators is endangered. In order to avoid the problem, the existing production process needs to be carried out in a glove box or a closed environment protected by inert gases such as argon and the like, which not only greatly increases equipment investment and process control difficulty, but also ensures that the production cost is high, thereby seriously impeding the industrialization process of the sulfide solid electrolyte. The attenuation mechanism of the air stability of the sulfide electrolyte is deeply explored, and the method is a precondition for formulating an effective improvement strategy. At present, most of sulfide electrolyte systems with higher ion conductivity contain P element, and according to a soft and hard acid-base theory, the sulfide electrolyte containing the P element has poor air stability, is easy to react with moisture and oxygen in the air, and generates toxic hydrogen sulfide gas, so that the structure of the electrolyte is destroyed, chemical components are changed, and performances such as ion conductivity and the like of the electrolyte are rapidly deteriorated. Lithium tin sulfur and phosphorus-free sulfide solid state electrolytes, in sharp contrast to phosphorothioate-based solid electrolytes, produce negligible hydrogen sulfide, whose structure and ionic conductivity can be recovered by heat treatment after soaking. However, the ionic conductivity of such sulfide solid state electrolytes is low, making it difficult to apply to all solid state batteries or as a modifying material in liquid lithium ion batteries. Therefore, the sulfide solid electrolyte is guaranteed to have good air stability and meanwhile the ionic conductivity is improved, and the technical problem to be solved is urgent. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a sulfide solid electrolyte, a preparation method and application thereof. The invention carries out the co-doping of Sr element, B element and O element on the solid electrolyte matrix material of sulfide which is lithium tin sulfur and has no phosphorus, improves the structural stability and ionic conductivity of the material, and further improves the air stability. In order to achieve the aim of the invention, the invention adopts the following technical scheme: In a first aspect, the present invention provides a sulfide solid state electrolyte comprising a lithium tin sulfide and phosphorus-free sulfide solid state electrolyte matrix material, and Sr element, B element, and O element doped in the lithium tin sulfide and phosphorus-free sulfide solid state electrolyte matrix material. In the sulfide solid state electrolyte of the present invention, the base material includes a lithium tin sulfide material in which Sr element, The co-doping of the B element and the O element, wherein the strontium element is +2 valent, sr 2+ replaces part of Li + (radius difference: about 76pm of Li + and about 118pm of Sr 2+), extra Li + vacancies are generated in crystal lattices due to charge mismatch, the vacancies serve as 'temporary sites' for migration of Li +, the ion migration energy barrier is reduced, meanwhile, the Li + conduction channel is widened, the electronegativity (1.0) of Sr 2+ is lower than that of Li +（0.98）、Na+ (0.93), the binding energy of the Sr 2+ and S 2− is higher (a more stable Sr-S bond is formed), the reaction of S 2− and H 2 O in air can be reduced, the air stability is improved, the B element can replace the Sn position in a small amount, the generation of H 2 S is inhibited, the air stability is further improved, the B element simultaneously forms BO 3/BO4 units by the B-O bond, the part S 2- is indirect