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CN-121983652-A - Dry-method coated g-C3N4Modified sulfide solid electrolyte and preparation method thereof

CN121983652ACN 121983652 ACN121983652 ACN 121983652ACN-121983652-A

Abstract

The invention relates to the technical field of new energy battery materials, in particular to a dry-coated g-C 3 N 4 modified sulfide solid electrolyte and a preparation method thereof. The preparation method comprises the steps of carrying out surface charge regulation treatment on g-C 3 N 4 through a pH buffer solution to obtain negatively charged g-C 3 N 4 , carrying out surface protonation treatment on sulfide solid electrolyte through a weak acid atmosphere to obtain positively charged sulfide solid electrolyte, mixing the negatively charged g-C 3 N 4 with the positively charged sulfide solid electrolyte, enabling the negatively charged g-C 3 N 4 to be adsorbed on the surface of the positively charged sulfide solid electrolyte through electrostatic adsorption, and carrying out cold isostatic pressing and low-temperature thermal diffusion to obtain the dry coated g-C 3 N 4 modified sulfide solid electrolyte. The electrolyte prepared by the method disclosed by the invention is more uniform and compact in coating and more firm in interface combination, and the performance of the electrolyte is obviously improved.

Inventors

  • ZHAO SILIANG
  • CHEN ZIHONG
  • ZHAO YIYI
  • LIU WEI

Assignees

  • 深圳固研新材料科技有限公司

Dates

Publication Date
20260505
Application Date
20260130

Claims (10)

  1. 1. The preparation method of the dry-coated g-C 3 N 4 modified sulfide solid electrolyte is characterized by comprising the following steps of: Carrying out surface charge regulation treatment on the g-C 3 N 4 by using a pH buffer solution with the pH value of 6-8, removing the pH buffer solution to obtain negatively charged g-C 3 N 4 , and carrying out surface protonizing treatment on the sulfide solid electrolyte by using a weak acid atmosphere with the pH value of 3-5 to obtain positively charged sulfide solid electrolyte; mixing the negatively charged g-C 3 N 4 with the positively charged sulfide solid electrolyte, and adsorbing the negatively charged g-C 3 N 4 on the surface of the positively charged sulfide solid electrolyte through electrostatic adsorption to obtain mixed powder; And (3) carrying out cold isostatic pressing treatment and low-temperature thermal diffusion treatment on the mixed powder to obtain the dry-coated g-C 3 N 4 modified sulfide solid electrolyte.
  2. 2. The method of claim 1, wherein the pH buffer is a phosphate buffer.
  3. 3. The method according to claim 1, wherein the surface charge control treatment of g-C 3 N 4 with a pH buffer having a pH of 6 to 8 comprises dispersing g-C 3 N 4 in a pH buffer having a pH of 6 to 8, stirring for 1 to 3 hours, and removing the pH buffer.
  4. 4. The method according to claim 1, wherein the step of removing the pH buffer solution comprises separating g-C 3 N 4 from the pH buffer solution by centrifugation or suction filtration, washing, and drying at 60-80 ℃ for 10-12 hours to obtain negatively charged g-C 3 N 4 ; Preferably, the washing is performed with deionized water for a plurality of times.
  5. 5. The method according to claim 1, wherein in the surface protonation treatment of the sulfide solid electrolyte by a weakly acidic atmosphere having a pH of 3 to 5, the weakly acidic atmosphere is a weakly acidic atmosphere in which dilute hydrochloric acid volatilizes, and the time of the surface protonation treatment is 1 to 4 hours.
  6. 6. The method of claim 1, wherein the mass ratio of said negatively charged g-C 3 N 4 to said positively charged sulfide solid state electrolyte in said mixing of said negatively charged g-C 3 N 4 and said positively charged sulfide solid state electrolyte is (0.5-2): 10.
  7. 7. The method according to claim 1, wherein the cold isostatic pressure treatment is performed at a pressure of 200-400MPa and a dwell time of 1-5 minutes.
  8. 8. The method according to claim 1, wherein the low temperature thermal diffusion treatment is carried out at a temperature of 150 to 200 ℃ for a holding time of 30 to 60 minutes.
  9. 9. The preparation method of the dry-coated g-C 3 N 4 modified sulfide solid electrolyte according to claim 1, wherein the preparation method further comprises post-treatment after the low-temperature thermal diffusion treatment, and the post-treatment specifically comprises the steps of crushing a sample obtained by the low-temperature thermal diffusion treatment, and sieving the crushed sample by a 200-300 mesh sieve.
  10. 10. The dry coated g-C 3 N 4 modified sulfide solid state electrolyte prepared by the method of any one of claims 1 to 9.

Description

Dry-coated g-C 3N4 modified sulfide solid electrolyte and preparation method thereof Technical Field The invention relates to the technical field of new energy battery materials, in particular to a dry-coated g-C 3N4 modified sulfide solid electrolyte and a preparation method thereof. Background Among various solid electrolyte systems, sulfide solid electrolytes, particularly LPSC system represented by Li 6PS5 Cl, have received extensive attention in academia and industry because of extremely high ionic conductivity (up to 10 -2-10-3 S/cm) at room temperature. However, LPSC materials face extremely severe "double-interface" challenges in practical applications, severely limiting their commercialization. The first is that the environment instability LPSC is extremely sensitive to moisture in the air, and trace water vapor can trigger the surface of the air to generate hydrolysis reaction to generate hydrogen sulfide (H 2 S) gas, so that the material performance is degraded, and serious potential safety hazards and environmental protection are brought. And secondly, electrochemical interface instability, namely, LPSC is easy to generate interface side reaction when in direct contact with a high-voltage positive electrode material (such as NCM ternary material) or a lithium metal negative electrode in the charge and discharge process of the battery, so that an interface layer with high impedance is formed, the transmission of lithium ions is blocked, and the cycle life of the battery is rapidly reduced. At present, a surface coating strategy is commonly adopted, namely, a functional protective layer is constructed on the surface of LPSC particles. Among them, graphite-phase carbon nitride (g-C 3N4) has been found to be a very potential cladding material in recent years as a nitrogen-rich two-dimensional nonmetallic polymer. Although the thought of g-C 3N4 coating is proposed, the existing preparation process still has the fundamental defect that in the wet coating process (such as solution mixing and sol-gel method), as LPSC is extremely easy to cause chemical reaction or hydrolysis in water or organic solvent, trace moisture or polar solvent is inevitably introduced in the wet process, so that impurity phases such as Li 2S、P2S5 and the like are generated on the surface of LPSC, the crystal structure of the impurity phases is seriously damaged, and the ionic conductivity is greatly attenuated. In the traditional dry physical mixing process (such as simple grinding and low-energy ball milling), physical mixing is carried out only by mechanical force, an effective driving force is lacking between the g-C 3N4 nano sheet and LPSC particles, uniform dispersion is difficult to realize, the binding force is poor, meanwhile, the coating layer is discontinuous, a compact and continuous core-shell structure cannot be formed, a large number of holes exist in the coating layer, and air cannot be effectively isolated and side reactions cannot be restrained. In the high temperature solid phase reaction method, the heat stability of LPSC is poor, and the structural change or volatilization of sulfur element is usually started at 200 ℃ or above. Conventional high temperature sintering processes (typically >400 ℃) are completely unsuitable for LPSC modification, and high temperatures can directly lead to electrolyte failure. Accordingly, there is a need for improvement and development in the art. Disclosure of Invention In view of the defects in the prior art, the invention aims to provide a dry-coated g-C 3N4 modified sulfide solid electrolyte and a preparation method thereof, and aims to solve the problem of poor coating effect in the existing process for coating the sulfide solid electrolyte. The technical scheme of the invention is as follows: The invention provides a preparation method of a dry-coated g-C 3N4 modified sulfide solid electrolyte, which comprises the following steps: Carrying out surface charge regulation treatment on the g-C 3N4 by using a pH buffer solution with the pH value of 6-8, removing the pH buffer solution to obtain negatively charged g-C 3N4, and carrying out surface protonizing treatment on the sulfide solid electrolyte by using a weak acid atmosphere with the pH value of 3-5 to obtain positively charged sulfide solid electrolyte; mixing the negatively charged g-C 3N4 with the positively charged sulfide solid electrolyte, and adsorbing the negatively charged g-C 3N4 on the surface of the positively charged sulfide solid electrolyte through electrostatic adsorption to obtain mixed powder; And (3) carrying out cold isostatic pressing treatment and low-temperature thermal diffusion treatment on the mixed powder to obtain the dry-coated g-C 3N4 modified sulfide solid electrolyte. Optionally, the pH buffer is a phosphate buffer. Optionally, the surface charge control treatment of the g-C 3N4 by the pH buffer with the pH of 6-8 specifically comprises dispersing the g-C 3N4 in the pH buffer with the pH