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CN-122025761-A - SiF-based material4Coating modified LATP solid electrolyte and preparation method thereof

CN122025761ACN 122025761 ACN122025761 ACN 122025761ACN-122025761-A

Abstract

The invention relates to the technical field of lithium battery electrolyte materials, and particularly discloses a modified LATP solid electrolyte based on a SiF 4 coating and a preparation method thereof, aiming at the problems of unstable morphology and chemical properties of lithium metal in the existing LATP solid electrolyte, wherein the LATP solid electrolyte comprises a LATP electrolyte substrate and a SiF 4 coating deposited on the surface of the LATP electrolyte substrate, the SiF 4 coating is connected with the LATP electrolyte substrate through Si-F bonds, the fluorine concentration in the SiF 4 coating is gradually decreased along the surface layer of the SiF 4 coating towards the direction of the LATP electrolyte substrate, the fluorine concentration of the surface layer of the SiF 4 coating is 20at%, and the fluorine concentration of the interior of the SiF 4 coating close to the LATP electrolyte substrate is 5at%. According to the invention, the silicon fluoride functionalized interface layer is constructed on the surface of the LATP solid electrolyte, so that double optimization of interface stability and ion transmission performance is realized, and the LATP solid electrolyte realizes improvement of stability of the lithium metal cathode through interface modification based on coating modification of SiF 4 .

Inventors

  • GU ZHENQI
  • WANG YUHENG
  • ZHAO TIANBAO
  • CHENG CAIWEI

Assignees

  • 成都锂能科技有限公司

Dates

Publication Date
20260512
Application Date
20260212

Claims (10)

  1. 1. A LATP solid electrolyte modified based on a SiF 4 coating, comprising a LATP electrolyte substrate and a SiF 4 coating deposited on the surface of the LATP electrolyte substrate, wherein the SiF 4 coating is connected with the LATP electrolyte substrate through Si-F bonds.
  2. 2. The LATP solid electrolyte modified based on SiF 4 coating as in claim 1 wherein the fluorine concentration in the SiF 4 coating is graded progressively along the surface layer of the SiF 4 coating toward the LATP electrolyte substrate.
  3. 3. The LATP solid electrolyte modified based on SiF 4 coating as claimed in claim 2, wherein the surface layer fluorine concentration of the SiF 4 coating is 20at%, and the internal fluorine concentration of the SiF 4 coating near the LATP electrolyte substrate is 5at%.
  4. 4. The LATP solid electrolyte modified based on SiF 4 coating according to claim 1 wherein the LATP electrolyte substrate has a thickness of 0.8-1.2mm and the SiF 4 coating has a thickness of 10-50nm.
  5. 5. A method of preparing a LATP solid electrolyte based on SiF 4 coating modification as claimed in any one of claims 1 to 4, characterized by the steps of: s1, preparing a LATP electrolyte substrate; s2, depositing SiF 4 coating on the surface of the LATP electrolyte substrate: And taking a LATP electrolyte substrate, adopting a chemical vapor deposition technology, taking SiF 4 as a precursor, reacting for 30-60min at 200-400 ℃, and forming a SiF 4 coating on the surface of the LATP electrolyte substrate to obtain the LATP solid electrolyte.
  6. 6. The method of preparing LATP solid electrolyte based on SiF 4 coating modification as claimed in claim 5, wherein the preparing LATP electrolyte substrate of step S1 comprises the steps of: S1.1, respectively taking lithium nitrate, aluminum nitrate nonahydrate, tetrabutyl titanate and ammonium dihydrogen phosphate, adding the lithium nitrate, the aluminum nitrate nonahydrate and the ammonium dihydrogen phosphate into deionized water, uniformly mixing to prepare a salt solution A; s1.2, taking a salt solution A, adding the solution B into the salt solution A under a stirring state to prepare a mixed solution C, adding a citric acid solution into the mixed solution C, and stirring and uniformly mixing to obtain a reaction solution; s1.3, heating the reaction solution to 60+/-10 ℃, stirring for reaction, standing to form sol, and drying at 80+/-10 ℃ to obtain xerogel; S1.4, grinding and crushing xerogel, then placing the crushed xerogel at 850-950 ℃ for calcining and cooling to obtain pure-phase LATP powder; S1.5, pressing pure-phase LATP powder into a LATP ceramic sheet, then placing the LATP ceramic sheet at 850-950 ℃ for sintering and cooling to obtain the LATP electrolyte substrate.
  7. 7. The method for preparing LATP solid electrolyte based on SiF 4 coating modification according to claim 6, wherein in step S1.3, stirring reaction is carried out for 4±1h, standing is carried out for 12±2h, and drying is carried out for 12±2h.
  8. 8. The method for preparing LATP solid electrolyte based on SiF 4 coating modification as claimed in claim 6, wherein in step S1.4, the temperature rising rate is controlled to be 2-5 ℃ per minute, the temperature keeping time is controlled to be 5-7h, and the cooling rate is controlled to be 2-5 ℃ per minute during calcination.
  9. 9. The method for preparing a LATP solid electrolyte based on a modification of a SiF 4 coating according to claim 6, wherein in step S1.5, the temperature rising rate is controlled to be 2-5 ℃ per minute, the heat preservation time is controlled to be 1-3 hours, and the cooling rate is controlled to be 2-5 ℃ per minute during sintering.
  10. 10. The method of preparing a LATP solid electrolyte based on SiF 4 coating modification as claimed in claim 5, wherein in step S2, the heating reaction is performed as follows: Heating from room temperature to 200+ -20deg.C at 3-8deg.C/min, and maintaining for 8-12min; Heating to 280+ -20deg.C at 1-3deg.C/min, and maintaining for 8-12min; heating to 350+ -20deg.C at 0.5-2deg.C/min, and maintaining for 15-25min; finally, heating to 400+/-20 ℃ at the temperature of 2-5 ℃ per minute, and preserving heat for 8-12 minutes.

Description

LATP solid electrolyte modified based on SiF 4 coating and preparation method thereof Technical Field The invention relates to the technical field of lithium battery electrolyte materials, in particular to a LATP solid electrolyte modified based on a SiF 4 coating and a preparation method thereof. Background The lithium ion battery has the advantages of high energy density, long cycle life and the like, and is widely applied to the fields of consumer electronics, new energy automobiles, energy storage power stations and the like. However, the organic electrolyte in the conventional lithium ion battery has safety problems such as volatilization, leakage, fire and the like, and the solid electrolyte is widely focused on due to its excellent electrochemical stability and safety, so that the above problems can be effectively solved by using the solid electrolyte instead of the electrolyte and the separator. In the classification of solid electrolytes, LATP in oxide solid electrolytes is a NASICON type solid electrolyte, and LATP refers to lithium aluminum titanium phosphate, which can be described as Li 1-xAlxTi2-x(PO4)3 in chemical formula, which is paid attention to and studied with high ion conductivity and wide electrochemical window, etc., and has a good development prospect. As disclosed in the patent publication CN116315125A, a LATP solid electrolyte and a method for preparing the same are proposed. However, the existing LATP solid electrolyte still has a plurality of problems that Ti 4+ in the LATP is easily reduced into Ti 3+ by lithium metal, an interface layer with poor conductivity such as Li-Ti-O phase is generated, the electrolyte structure is degraded and the ion transmission is blocked, and the lithium deposition is uneven due to a rigid solid-solid interface, so that lithium dendrite growth, interface resistance surge and the like are caused. Disclosure of Invention The invention aims to solve the problems of unstable form and chemical property of lithium metal in the existing LATP solid electrolyte. The invention is realized by the following technical scheme: The invention provides a LATP solid electrolyte modified based on a SiF 4 coating, which comprises a LATP electrolyte substrate and a SiF 4 coating deposited on the surface of the LATP electrolyte substrate, wherein the SiF 4 coating is connected with the LATP electrolyte substrate through Si-F bonds. Preferably, the fluorine concentration in the SiF 4 coating is graded progressively along the surface layer of the SiF 4 coating toward the LATP electrolyte substrate. Preferably, the surface layer fluorine concentration of the SiF 4 coating is 20at%, and the internal fluorine concentration of the SiF 4 coating near the LATP electrolyte substrate is 5at%. Preferably, the LATP electrolyte substrate has a thickness of 0.8-1.2mm and the SiF 4 coating has a thickness of 10-50nm. The invention also provides a preparation method of the LATP solid electrolyte based on SiF 4 coating modification, which comprises the following steps: s1, preparing a LATP electrolyte substrate; s2, depositing SiF 4 coating on the surface of the LATP electrolyte substrate: And taking a LATP electrolyte substrate, adopting a chemical vapor deposition technology, taking SiF 4 as a precursor, reacting for 30-60min at 200-400 ℃, and forming a SiF 4 coating on the surface of the LATP electrolyte substrate to obtain the LATP solid electrolyte. Preferably, the preparing of the LATP electrolyte substrate of step S1 comprises the steps of: S1.1, respectively taking lithium nitrate, aluminum nitrate nonahydrate, tetrabutyl titanate and ammonium dihydrogen phosphate, adding the lithium nitrate, the aluminum nitrate nonahydrate and the ammonium dihydrogen phosphate into deionized water, uniformly mixing to prepare a salt solution A; s1.2, taking a salt solution A, adding the solution B into the salt solution A under a stirring state to prepare a mixed solution C, adding a citric acid solution into the mixed solution C, and stirring and uniformly mixing to obtain a reaction solution; s1.3, heating the reaction solution to 60+/-10 ℃, stirring for reaction, standing to form sol, and drying at 80+/-10 ℃ to obtain xerogel; S1.4, grinding and crushing xerogel, then placing the crushed xerogel at 850-950 ℃ for calcining and cooling to obtain pure-phase LATP powder; S1.5, pressing pure-phase LATP powder into a LATP ceramic sheet, then placing the LATP ceramic sheet at 850-950 ℃ for sintering and cooling to obtain the LATP electrolyte substrate. Preferably, in step S1.3, the reaction is stirred for 4+ -1 h, left to stand for 12+ -2 h and dried for 12+ -2 h. Preferably, in the step S1.4, the temperature rising rate is controlled to be 2-5 ℃ per minute, the heat preservation time is 5-7 hours, and the cooling rate is controlled to be 2-5 ℃ per minute during calcination. Preferably, in the step S1.5, during sintering, the temperature rising rate is controlled to be 2-5 ℃ per minute, the heat