Search

CN-122025760-A - High-fluorine doped halide electrolyte and preparation method thereof

CN122025760ACN 122025760 ACN122025760 ACN 122025760ACN-122025760-A

Abstract

The invention relates to a high-fluorine doped halide solid electrolyte, which has a chemical expression of Li 3+0.25x M 1‑0.25x Cl 4‑x O 1.5‑ 0.375x F x , wherein M is at least one selected from Zr 4+ 、Hf 4+ , x is more than or equal to 1.0 and less than or equal to 2.0, the high-fluorine doped halide solid electrolyte has a composite structure with a lithium-rich amorphous phase as a matrix, a microcrystalline phase is embedded in the matrix, the microcrystalline phase does not contain LiCl, the total number of lithium atoms in the high-fluorine doped halide solid electrolyte is taken as a reference, the proportion of lithium atoms distributed in the amorphous phase is 80 at% -95 at%, and the rest of lithium atoms are distributed in the microcrystalline phase. The invention combines unique material composition design and low-temperature ball milling process to obtain the halide electrolyte with a composite structure with lithium-rich amorphous phase as a matrix and nano microcrystal embedded, and the microcrystal phase does not contain LiCl, so that the contradiction between high fluorine doping amount and high ion conductivity is solved.

Inventors

  • SUN CHUNWEN
  • LIU XINGKUN

Assignees

  • 中国矿业大学(北京)

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. A high-fluorine doped halide solid electrolyte is characterized by having a chemical expression of Li 3+0.25x M 1-0.25x Cl 4- x O 1.5-0.375x F x , wherein M is at least one selected from Zr 4+ 、Hf 4+ , x is more than or equal to 1.0 and less than or equal to 2.0, the high-fluorine doped halide solid electrolyte has a composite structure with a lithium-rich amorphous phase as a matrix and a microcrystalline phase intercalated into the lithium-rich amorphous phase, the microcrystalline phase does not contain LiCl, the total number of lithium atoms in the high-fluorine doped halide solid electrolyte is taken as a reference, the proportion of lithium atoms distributed in the amorphous phase is 80 at% -95 at%, and the rest of lithium atoms are distributed in the microcrystalline phase.
  2. 2. The high fluorine doped halide solid electrolyte according to claim 1, wherein the microcrystalline phase is present in the high fluorine doped halide solid electrolyte in an amount of 3 to 10 wt%.
  3. 3. The high fluorine doped halide solid electrolyte according to claim 1, wherein the grain size of the microcrystalline phase is 5 to 20 nm.
  4. 4. The high fluorine doped halide solid electrolyte according to claim 1, wherein the proportion of lithium atoms distributed in the amorphous phase is 85 at% -92 at%, preferably 85 at% -90 at%, based on the total number of lithium atoms in the high fluorine doped halide solid electrolyte.
  5. 5. The highly fluorine doped halide solid electrolyte of claim 1 wherein M is Zr 4+ .
  6. 6. The high fluorine doped halide solid electrolyte of claim 1, wherein x is 1.0-1.5.
  7. 7. The method for preparing the high-fluorine-doped halide solid electrolyte according to any one of claims 1 to 6, which is characterized by comprising the steps of mixing Li 2 O, liF and MCl 4 according to the stoichiometric ratio of a chemical expression Li 3+0.25x M 1-0.25x Cl 4-x O 1.5-0.375x F x to obtain a precursor, and then ball-milling the precursor at-20-10 ℃ in an inert atmosphere to obtain the high-fluorine-doped halide solid electrolyte.
  8. 8. The method according to claim 7, wherein the ball milling temperature is 0-10 ℃.
  9. 9. The preparation method of the ball mill according to claim 7, wherein the inert atmosphere is nitrogen and/or argon, the ball milling condition is that the ball-material ratio is 10-50:1, preferably 20-30:1, the ball milling rotating speed is 300-800 rpm, preferably 500-600 rpm, the ball milling mode adopts a positive and negative rotation strategy, the forward and reverse rotation time is 3-20 min respectively, the middle interval is 1-10 min, and the total ball milling time is 5-48 h, preferably 10-20 h.
  10. 10. Use of a highly fluorine doped halide solid electrolyte according to any one of claims 1 to 6 in an all solid state lithium battery, characterized in that it is used in combination with a high voltage cathode material selected from LiCoO 2 or spinel LiMn 2 O 4 .

Description

High-fluorine doped halide electrolyte and preparation method thereof Technical Field The invention belongs to the technical field of inorganic solid electrolytes, and particularly relates to a high-fluorine doped halide electrolyte and a preparation method thereof. Background With the rapid development of electric automobiles and portable electronic equipment markets, higher requirements are put on the safety, energy density and cycle life of energy storage systems. The all-solid-state lithium battery (ASSLBs) adopts the nonflammable inorganic solid electrolyte to replace the traditional organic liquid electrolyte, so that the potential safety hazard of thermal runaway of the battery is fundamentally solved, and meanwhile, the lithium battery has the potential of realizing higher energy density and longer cycle life, and is regarded as one of the most potential energy storage systems. The solid electrolyte serves as a core component of ASSLBs, and the ionic conductivity, electrochemical stability window and interfacial compatibility with electrode materials are key to determine the overall performance of the battery. Currently, many solid electrolytes mainly include three major classes of oxides, sulfides, and halides. Among them, the halide solid electrolyte is receiving attention because of its high ionic conductivity, good deformability, and interfacial stability to the oxide cathode material. However, to achieve higher energy densities, high voltage cathode materials (e.g., nickel-rich layered oxides, high voltage spinels, etc.) need to be matched, which requires a wider voltage stability window for the solid electrolyte. The introduction of fluorine (F) is one of the effective strategies for improving the high voltage resistance of the halide electrolyte, because F - has higher electronegativity and can improve the oxidative decomposition potential of the electrolyte. At the same time, however, fluorine doping tends to disrupt the lithium ion transport channels in the halide lattice, resulting in a decrease in ion conductivity, creating a contradiction between high voltage stability and high ion conductivity. Therefore, the high fluorine doped halide electrolyte in the prior art is generally accompanied by serious reduction of ion conductivity, and is difficult to meet the practical application requirements of the high-power and long-service-life all-solid-state battery. Therefore, developing a novel halide solid electrolyte capable of maintaining both high ionic conductivity and excellent high voltage resistance at high fluorine doping levels has become a key technical challenge in driving the development of high energy density all-solid-state batteries. Disclosure of Invention The invention aims to overcome the defects of the prior art, solve the technical contradiction of the reduction of ionic conductivity of the high-fluorine doped halide electrolyte caused by fluorine introduction, and provide a halide solid electrolyte with high ionic conductivity and high pressure resistance at a high fluorine doping level and a preparation method thereof. In order to achieve the above purpose, the present invention adopts the following technical scheme: The chemical expression of the high-fluorine doped halide solid electrolyte is Li 3+0.25xM1-0.25xCl4-xO1.5-0.375xFx, wherein M is at least one selected from Zr 4+、Hf4+, x is more than or equal to 1.0 and less than or equal to 2.0, the high-fluorine doped halide solid electrolyte has a composite structure with a lithium-rich amorphous phase as a matrix, a microcrystalline phase is intercalated into the lithium-rich amorphous phase, the microcrystalline phase does not contain LiCl, the total number of lithium atoms in the high-fluorine doped halide solid electrolyte is taken as a reference, the ratio of lithium atoms distributed in the amorphous phase is 80 at% -95 at%, and the rest of lithium atoms are distributed in the microcrystalline phase. The distribution ratio of lithium atoms indirectly reflects the ratio of the two phases, and the lower the ratio of lithium atoms distributed in the microcrystalline phase is, the lower the ratio of the microcrystalline phase in the high fluorine-doped halide solid electrolyte is. Since the lithium atom proportion distributed in the amorphous phase is significantly higher than that of the microcrystalline phase, the material is shown to form a composite structure with a lithium-rich amorphous phase as a main body and nano-crystallites embedded. Further, the microcrystalline phase accounts for 3-10wt% of the high fluorine doped halide solid electrolyte. The grain size of the microcrystalline phase is 5-20 nm. Preferably, the total number of lithium atoms in the high-fluorine doped halide solid electrolyte is taken as a reference, the ratio of lithium atoms distributed in the amorphous phase is 85 at% -92% at%, the rest of lithium atoms are distributed in the microcrystalline phase, more preferably, the ratio of lithium at