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CN-121983689-A - Metal lithium alloy modified layer and preparation method thereof

CN121983689ACN 121983689 ACN121983689 ACN 121983689ACN-121983689-A

Abstract

The invention discloses a metal lithium alloy modified layer and a preparation method thereof, and relates to the technical field of energy storage devices, wherein the modified layer is arranged on the surface of a lithium metal negative electrode, the structure of the modified layer is a composite film containing a metal lithium alloy phase and an inorganic fluoride phase, the metal lithium alloy phase is formed by in-situ alloying of lithium and at least one lithium-philic metal M selected from silver, magnesium, aluminum, tin, zinc and indium, the inorganic fluoride phase is at least one selected from lithium fluoride, magnesium fluoride, aluminum fluoride and tin fluoride, the thickness of the composite film is 20-300 nm, and the adopted magnetic control co-sputtering technology can realize uniform compounding and accurate regulation of an alloy phase and a fluoride phase on a nanometer scale in a process aspect, and the process is clean, efficient and good in repeatability.

Inventors

  • WEI GUANGFU
  • GAO HONGTAO
  • JIANG YUPENG
  • ZHOU PENGFEI
  • WANG YINGJIE

Assignees

  • 青岛新卫仕新能源科技有限公司

Dates

Publication Date
20260505
Application Date
20260109

Claims (6)

  1. 1. The metal lithium alloy modified layer is characterized in that the modified layer is arranged on the surface of a lithium metal anode, and the modified layer has a structure of a composite film containing a metal lithium alloy phase and an inorganic fluoride phase; Wherein the metal lithium alloy phase is formed by in-situ alloying of lithium and at least one lithium-philic metal M selected from silver, magnesium, aluminum, tin, zinc and indium; the inorganic fluoride phase is at least one selected from lithium fluoride, magnesium fluoride, aluminum fluoride and tin fluoride; The thickness of the composite film is 20-300 nm.
  2. 2. The modified layer of claim 1, wherein the molar ratio of the lithium-philic metal M to the metal element in the inorganic fluoride phase in the composite film is 1:5 to 5:1.
  3. 3. The modified metal lithium alloy layer of claim 1, wherein the composite film has a thickness of 50 to 150 nm a.
  4. 4. A method of preparing a metallic lithium alloy interface modification layer as claimed in any one of claims 1 to 3, comprising the steps of: (1) Under the protection of inert atmosphere, placing a lithium metal substrate in a deposition chamber of a magnetron sputtering device; (2) Setting a target material, namely installing at least one lithium-philic metal M target and at least one inorganic fluoride target in the deposition cavity; (3) Setting deposition parameters, namely pumping the background vacuum degree of a deposition chamber to be less than 5.0x10 < -3 > Pa, introducing inert working gas, and maintaining the working gas pressure to be 0.2-1.0 Pa; (4) And co-sputtering and depositing, namely exciting the lithium-philic metal M target and the inorganic fluoride target simultaneously, performing co-sputtering on the surface of the lithium metal substrate for 3-30 minutes, performing alloying reaction on metal M atoms sputtered from the lithium-philic metal M target and lithium atoms on the surface of the lithium metal substrate in the depositing process to form the metal lithium alloy phase in situ, and forming the inorganic fluoride phase from fluoride components sputtered from the inorganic fluoride target to jointly form the composite film.
  5. 5. The method according to claim 4, wherein the lithium-philic metal M target is a metal target having a purity of 99.9% or more, and the inorganic fluoride target is a sintered ceramic target having a purity of 99.5% or more.
  6. 6. The method of claim 4, wherein the inert working gas is argon, the lithium-philic metal M target is excited by a direct current power source with a power density of 2-6W/cm 2, and the inorganic fluoride target is excited by a radio frequency power source with a power density of 3-10W/cm 2.

Description

Metal lithium alloy modified layer and preparation method thereof Technical Field The invention relates to the technical field of energy storage devices, in particular to a metal lithium alloy modified layer and a preparation method thereof. Background Lithium metal anodes are considered to be one of the key materials for achieving high energy density battery systems due to their high specific capacity and low electrochemical potential. However, in the actual charge-discharge cycle, the interface between lithium metal and electrolyte has an unstable problem, which is mainly represented by the formation of dendrites by non-uniform deposition of lithium, and the continuous side reaction of the interface consumes active substances and electrolyte, which severely restricts the cycle life and safety performance of the lithium metal battery. To solve the above problems, various strategies for interface modification have been proposed by those skilled in the art. Among them, metal lithium alloying is an effective means. A metallic lithium alloy refers to a compound or solid solution of lithium with other metals (e.g., silver, magnesium, tin, etc.). The material generally has better lithium ion conduction capability and specific lithium-philic property, and can guide uniform deposition of lithium ions to a certain extent so as to alleviate dendrite problems. For example, by depositing a layer of metal such as silver or magnesium on the surface of lithium metal in advance and forming a corresponding lithium alloy layer by alloying reaction with lithium, uniformity of lithium deposition can be improved. However, there is still a technical problem in a single metal lithium alloy layer in that, on the one hand, volume changes may occur in the alloy layer during repeated lithium deposition/stripping processes, possibly resulting in structural failure. On the other hand, the alloy layer is not sufficiently chemically stable against some electrolytes, and it is difficult to completely prevent side reactions at the interface. For example, in conventional carbonate electrolytes, continued decomposition reactions may still occur at the simple lithium alloy interface. Therefore, a metal lithium alloy modified layer and a preparation method thereof are designed to solve the technical problems. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a metal lithium alloy modified layer and a preparation method thereof, and solves the technical problems in the background art. The metal lithium alloy modified layer is arranged on the surface of a lithium metal anode, and the structure of the metal lithium alloy modified layer is a composite film containing a metal lithium alloy phase and an inorganic fluoride phase; Wherein the metal lithium alloy phase is formed by in-situ alloying of lithium and at least one lithium-philic metal M selected from silver, magnesium, aluminum, tin, zinc and indium; the inorganic fluoride phase is at least one selected from lithium fluoride, magnesium fluoride, aluminum fluoride and tin fluoride; The thickness of the composite film is 20-300 nm. Preferably, in the composite film, the molar ratio of the lithium-philic metal M to the metal element in the inorganic fluoride phase is 1:5 to 5:1. Preferably, the thickness of the composite film is 50-150 nm a. The preparation method of the metal lithium alloy interface modification layer comprises the following steps: (1) Under the protection of inert atmosphere, placing a lithium metal substrate in a deposition chamber of a magnetron sputtering device; (2) Setting a target material, namely installing at least one lithium-philic metal M target and at least one inorganic fluoride target in the deposition cavity; (3) Setting deposition parameters, namely pumping the background vacuum degree of a deposition chamber to be less than 5.0x10 < -3 > Pa, introducing inert working gas, and maintaining the working gas pressure to be 0.2-1.0 Pa; (4) And co-sputtering and depositing, namely exciting the lithium-philic metal M target and the inorganic fluoride target simultaneously, performing co-sputtering on the surface of the lithium metal substrate for 3-30 minutes, performing alloying reaction on metal M atoms sputtered from the lithium-philic metal M target and lithium atoms on the surface of the lithium metal substrate in the depositing process to form the metal lithium alloy phase in situ, and forming the inorganic fluoride phase from fluoride components sputtered from the inorganic fluoride target to jointly form the composite film. Preferably, the lithium-philic metal M target is a metal target with purity more than or equal to 99.9%, and the inorganic fluoride target is a sintered ceramic target with purity more than or equal to 99.5%. Preferably, the inert working gas is argon, the lithium-philic metal M target is excited by a direct-current power supply, the power density is 2-6W/cm < 2 >, and the inorganic fluoride target is