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CN-122025757-A - Sulfide solid electrolyte, preparation method thereof and lithium ion battery

CN122025757ACN 122025757 ACN122025757 ACN 122025757ACN-122025757-A

Abstract

The invention relates to the technical field of lithium batteries, and provides a sulfide solid electrolyte, a preparation method thereof and a lithium ion battery. The sulfide solid electrolyte has a chemical general formula of Li 7+x P 1‑ y S 6‑β O β M y , wherein x=y (5-M), M is an average valence state of M, y is more than or equal to 0.01 and less than or equal to 0.2,0.1 and is less than or equal to 0.5, M comprises at least one of Sn, sb, al and Zr, and the surface of the electrolyte particle is provided with a Li-M-O interface layer. The M element is partially fused into crystal lattice during heat treatment to stabilize structure, and the M element has high affinity to oxygen and may react with oxygen before the main sulfide in subsequent treatment. The sulfide solid electrolyte disclosed by the invention has the advantages that the air stability and the interface compatibility with a high-voltage anode are obviously improved while the high ionic conductivity is kept, and the preparation method is simple, low in cost and suitable for large-scale production.

Inventors

  • ZHANG JINGZHE
  • QIN JIAN
  • TONG JINLIN
  • YE QING
  • LIANG WEI

Assignees

  • 孝感楚能新能源创新科技有限公司

Dates

Publication Date
20260512
Application Date
20260130

Claims (10)

  1. 1. A sulfide solid electrolyte is characterized in that the chemical general formula of the sulfide solid electrolyte is Li 7+ x P 1-y S 6-β O β M y , wherein x=y (5-M), M is the average valence state of M, y is more than or equal to 0.01 and less than or equal to 0.2,0.1 and is less than or equal to 0.5, M comprises at least one of Sn, sb, al and Zr, The surface of the sulfide solid electrolyte particles is provided with a Li-M-O interface layer.
  2. 2. A method for preparing a sulfide solid state electrolyte as claimed in claim 1, comprising the steps of: S1, preparing and mixing a precursor, namely weighing a lithium source, a phosphorus source, a sulfur source and an M source according to a general formula metering ratio, and performing ball milling treatment under the protection of inert atmosphere to obtain a uniformly mixed precursor; S2, heat treatment, namely sintering the precursor in an inert atmosphere, and cooling the precursor along with a furnace after the sintering is finished to obtain a sulfide electrolyte matrix; s3, crushing and screening, namely mechanically crushing and screening the sintered blocks; S4, in-situ interface construction, namely placing the sieved powder into treatment equipment capable of introducing air flow, introducing gas mixed by dry oxygen and inert gas into the equipment at the temperature of 20-50 ℃, and treating for 10-60min to generate an amorphous Li-M-O interface layer; S5, post-treatment, namely vacuum drying the treated powder in inert atmosphere to obtain a final product.
  3. 3. The method for preparing a sulfide solid state electrolyte as claimed in claim 2, wherein in the step S1, the lithium source, the phosphorus source and the M source are sulfide, and the sulfur source is derived from the lithium source, the phosphorus source and the M source.
  4. 4. The method for preparing sulfide solid electrolyte according to claim 2, wherein the ball milling process in step S1 has a ball mass ratio of 5-20:1, a ball milling rotation speed of 300-800rpm, and a ball milling time of 5-24 hours.
  5. 5. The method for producing a sulfide solid state electrolyte as claimed in claim 2, wherein the step S2 is heat-treated to raise the temperature to 450 to 550 ℃ at a rate of 5 to 10 ℃ per minute, and sintered for 2 to 8 hours.
  6. 6. The method for producing a sulfide solid state electrolyte as claimed in claim 2, wherein in step S3, the mesh size is 1 to 20 μm.
  7. 7. The method for producing a sulfide solid state electrolyte as claimed in claim 2, wherein in step S4, the dry oxygen accounts for 1 to 5% by volume of the inert gas.
  8. 8. The method for producing a sulfide solid state electrolyte as claimed in claim 2, wherein in step S5, the drying is performed under vacuum at 50 to 80 ℃ for 2 to 4 hours.
  9. 9. The method for producing a sulfide solid state electrolyte as claimed in claim 2, wherein in steps S1 to S5, the inert atmosphere and the inert gas are Ar or N 2 .
  10. 10. A lithium ion battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the sulfide solid state electrolyte of claim 1.

Description

Sulfide solid electrolyte, preparation method thereof and lithium ion battery Technical Field The invention relates to the technical field of lithium batteries, in particular to a sulfide solid electrolyte, a preparation method thereof and a lithium ion battery. Background Solid-state lithium batteries are the core of the next generation energy storage technology. The sulfide solid electrolyte is one of the electrolyte materials with the most application prospect because of high lithium ion conductivity (up to 10 -2 S/cm level). However, the industrialization of the electrolyte has the fatal defects that firstly, the electrolyte is poor in environmental stability, is extremely sensitive to moisture in the air, can generate a hydrolysis reaction to generate highly toxic and explosive hydrogen sulfide gas, and causes the structural damage and the loss of conductivity of the electrolyte. This requires that the whole process from synthesis to battery assembly must be carried out in an inert atmosphere at extremely high cost, greatly pushing up the manufacturing costs. Secondly, the interface compatibility is poor, and particularly when the electrolyte is contacted with a positive electrode material (such as lithium cobaltate, a lithium-rich manganese-based material, a high-nickel ternary material and the like) with the working voltage higher than 4V (vs. Li +/Li), sulfide electrolyte is easy to oxidize, and a high-impedance decomposition layer is formed at the interface, so that the internal resistance of the battery is increased rapidly, the capacity is attenuated rapidly and the cycle life is shortened. The existing improvement technology, such as element doping (O, se, ge and the like) or surface coating (Li 2ZrO3、LiTaO3 and the like), can improve the performance in a certain aspect to a certain extent, but always has the following limitations that the element doping usually takes part of ion conductivity as a cost, and the improvement on air stability is limited, so that the severe environment requirements of industrialization cannot be fundamentally solved. Surface coating is generally complex in process, uniformity of the coating is difficult to control, and additional coatings introduce interface resistance, which is unfavorable for ion conduction. In addition, the above methods often use expensive elements such as Ge, ta, etc., or require complicated vapor deposition equipment, which is costly. Therefore, developing a sulfide solid electrolyte with low cost, simple process and capability of synchronously solving the environmental stability and interface compatibility has become a technical problem to be solved in the field. Disclosure of Invention In view of the above, the invention provides a sulfide solid electrolyte, a preparation method thereof and a lithium ion battery, wherein the electrolyte has remarkably improved air stability and interface compatibility with a high-voltage positive electrode while maintaining high ion conductivity, and the preparation method is simple, low in cost and suitable for large-scale production. The technical scheme of the invention is realized in that in the first aspect, the invention provides a sulfide solid electrolyte, which has a chemical general formula of Li 7+xP1-yS6-βOβMy, wherein x=y (5-M), M is the average valence state of M, and y is more than or equal to 0.01 and less than or equal to 0.2,0.1 and beta is more than or equal to 0.5; M comprises at least one of Sn, sb, al and Zr; The surface of the sulfide solid electrolyte particles is provided with a layer of amorphous Li-M-O interface layer which is generated through in-situ reaction and has the thickness of 1-15 nm. The invention designs a sulfur oxide system with Sn, al and the like as key doping elements (M). The M element is partially fused into crystal lattice during heat treatment to stabilize structure, and the M element has high affinity to oxygen and may react with oxygen before the main sulfide in subsequent treatment. In a second aspect, the present invention provides a method for preparing a sulfide solid state electrolyte, comprising the steps of: S1, preparing and mixing a precursor, namely weighing a lithium source, a phosphorus source, a sulfur source and an M source according to a general formula metering ratio, and performing ball milling treatment under the protection of inert atmosphere to obtain a uniformly mixed precursor; s2, heat treatment, namely sintering the precursor in an inert atmosphere, and cooling along with a furnace after the sintering is finished to obtain a sulfide electrolyte matrix with good crystallization; S3, crushing and screening, namely mechanically crushing and screening the sintered blocks, wherein the step is favorable for uniformity and efficiency of subsequent treatment; S4, in-situ interface construction, namely placing the sieved powder into treatment equipment (such as a fluidized bed, a roller mixer or a static treatment chamber) capable of introducin