CN115863533A - Lithium metal cathode protection process for sulfide-based all-solid-state battery by using LBO self-supporting film - Google Patents

Abstract

The invention relates to the technical field of solid-state batteries, and discloses a lithium metal negative electrode protection process for a sulfide-based all-solid-state battery by using an LBO self-supporting film, which comprises an LBO compound, wherein the wet preparation process of the LBO compound comprises the following steps: s1, adding H ₃ BO ₃ Dissolving the mixture and LiOH in a solvent according to a proportion to obtain a mixture A with the concentration of 0.02-0.05 mol/L; s2, ultrasonically dispersing the mixture A obtained in the step S1 for 0.5-1h, and then stirring to obtain slurry B; s3, coating the slurry B on lithium metal, and drying for 1-3h in a rare gas atmosphere at the drying temperature of 70-120 ℃ to obtain LBO @ Li. The invention is realized by the way between a lithium metal negative electrode and a sulfide solid electrolyteThe addition of a layer of LBO self-supporting film greatly improves the compatibility with a lithium metal cathode, and the lithium metal cathode is used for an all-solid-state battery, and has better cycle performance.

Description

A self-supporting LBO thin film for lithium metal anode in sulfide-based all-solid-state batteries protection process

technical field

The invention relates to the technical field of solid-state batteries, in particular to an LBO self-supporting thin film used for the lithium metal negative electrode protection process of a sulfide-based all-solid-state battery.

Background technique

The all-solid-state battery replaces the traditional organic flammable electrolyte with a non-flammable solid electrolyte, which fundamentally avoids safety problems. At present, solid electrolytes mainly include oxides, sulfides, and polymer solid electrolytes. Among them, oxide solid electrolytes are not afraid of water and oxygen, and have relatively stable physical and chemical properties, but low conductivity. Polymer solid electrolyte is formed by the complexation of polar polymers and metal salts. It has good film-forming properties, flexibility and high safety performance, but it has low electrical conductivity, small migration number of lithium ions, and poor mechanical properties. and other shortcomings. The sulfide solid electrolyte has an ionic conductivity comparable to that of a liquid electrolyte solution, and has a wide electrochemical window, which can be adapted to high-voltage cathode materials. However, due to the serious side reactions between the sulfide solid electrolyte and lithium metal, it is incompatible with lithium anodes, which is severely limited. its application in all-solid-state batteries.

Therefore, the present invention proposes a LBO self-supporting thin film used in the lithium metal negative electrode protection process of sulfide-based all-solid-state batteries to solve the above problems.

Contents of the invention

The purpose of the present invention is to solve the shortcomings in the prior art, and propose a kind of LBO self-supporting film for the lithium metal negative electrode protection process of sulfide-based all-solid-state batteries.

The present invention provides a kind of LBO self-supporting film used in the lithium metal negative electrode protection process of sulfide-based all-solid-state battery, including LBO compound, and the wet preparation process of the LBO compound includes the following steps:

S1. Dissolving H ₃ BO ₃ and LiOH in a solvent in proportion to obtain a mixture A with a concentration of 0.02-0.05 mol/L;

S2. Ultrasonic disperse the mixture A obtained in step S1 for 0.5-1 h, and then stir to obtain slurry B;

S3, coating the slurry B on the lithium metal, drying in a rare gas atmosphere for 1-3 hours at a drying temperature of 70-120°C to obtain LBO@Li;

S4. Take out the LBO@Li, and use the LBO@Li negative electrode, electrolyte, and positive electrode to form an all-solid-state battery.

Preferably, the molecular formula of the LBO compound is Li _{x By} O _z , where x+y+z=1.

Preferably, the LBO compound also has a dry preparation process.

Preferably, in the S1, the molar ratio of H ₃ BO ₃ to LiOH is 1:(1-3).

Preferably, in the S1, the solvent is ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl formate, methyl acetate, methyl butyrate , ethyl propionate, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane or one or more.

Preferably, in said S3, the rare gas is argon.

Preferably, in S3, the coating method is spin coating or blade coating.

Compared with the prior art, the beneficial effect of the present invention is: the use of the LBO compound material has the characteristics of electrochemical stability and lithium ion fast conduction, under its protection, the LBO compound material can not only be used as a high-efficiency solid electrolyte intermediate layer, induce The ultra-dense deposition of Li can also isolate Li metal from the electrolyte, provide a good environment for stable Li plating/stripping, effectively inhibit lithium loss and electrolyte decomposition during cycling, and have high stability. The process of the present invention is simple and efficient , low cost and suitable for commercial mass production.

Description of drawings

Figure 1 is a long-term cycle diagram of an all-solid-state battery prepared in Example 1 of the present invention with an interface of an LBO self-supporting film.

Fig. 2 is a long-term cycle diagram of an all-solid-state battery assembled without adding LBO self-supporting film in Comparative Example 1 of the present invention.

3 is the impedance spectrum of the all-solid-state battery of Example 1 and Comparative Example 1.

Detailed ways

The present invention will be further explained below in conjunction with specific embodiments.

The all-solid-state battery of the present invention includes a positive electrode part, an electrolyte part, and an LBO@Li negative electrode part, wherein the positive electrode part is constructed by mixing positive electrode active materials, sulfide solid electrolytes, and conductive carbon, and the positive electrode active materials are spinel-type transition metal oxides, One or a mixture of layered lithium transition metal oxides and olivine.

The preparation method of the all-solid-state battery provided by the present invention first prepares the positive electrode, mixes the positive electrode material, conductive carbon black and sulfide solid electrolyte according to a certain ratio, and grinds and mixes them evenly. The battery assembly step is to place the solid electrolyte powder in the tablet mold and press it into a solid electrolyte sheet, then place the positive electrode sheet on one side of the solid electrolyte, press it with pressure, and finally attach LBO@ on the other side of the solid electrolyte Li foil, pressed into a sandwich-structured all-solid-state battery.

Example 1

As shown in Figure 1, weigh _H3BO3 and LiOH in the glove box according to the molar ratio of 1:3, then add these reactant raw materials into a _10ml small beaker, and then add ethylene carbonate solvent, the concentration is 0.025mol/L, Let these raw materials be fully stirred and contacted to obtain the LBO precursor slurry; the precursor slurry was spin-coated on Li foil, dried in a glove box at 90 °C for 2 hours, and cut into pieces to obtain the LBO@Li material.

The composite material of sulfide solid electrolyte material and cathode material. Mix it with conductive carbon black and binder at a ratio of 20:75:1:4, and grind it evenly to obtain positive electrode powder. The positive electrode powder was dissolved in DME, stirred evenly by magnetic force and coated on aluminum foil. Place the powder of the sulfide solid electrolyte material in a tablet mold and press it into a solid electrolyte sheet, then place the positive electrode sheet on one side of the solid electrolyte and press it with pressure, and finally attach LBO@ on the other side of the solid electrolyte Li, pressed into an all-solid-state battery.

Comparative case 1

As shown in Figure 2, no treatment is done on the interface between the lithium metal negative electrode and the sulfide solid electrolyte. A layer of LBO self-supporting film, the compatibility with lithium metal anode has been greatly improved, and it is used in all-solid-state batteries, and its cycle performance is better.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (7)

1. A kind of LBO self-supporting thin film is used for the lithium metal negative electrode protection technology of sulfide-based all-solid-state battery, is characterized in that, comprises LBO compound, and the wet method preparation flow process of described LBO compound comprises the following steps: S1. Dissolving H ₃ BO ₃ and LiOH in a solvent in proportion to obtain a mixture A with a concentration of 0.02-0.05 mol/L; S2. Ultrasonic disperse the mixture A obtained in step S1 for 0.5-1 h, and then stir to obtain slurry B; S3, coating the slurry B on the lithium metal, drying in a rare gas atmosphere for 1-3 hours at a drying temperature of 70-120°C to obtain LBO@Li; S4. Take out the LBO@Li, and use the LBO@Li negative electrode, electrolyte, and positive electrode to form an all-solid-state battery. 2. A kind of LBO self-supporting film according to claim 1 is used for the lithium metal negative electrode protection process of sulfide-based all-solid-state battery, it is characterized in that, described LBO compound molecular formula is Li _{x By} O _z , wherein x+ y+z=1. 3. A kind of LBO self-supporting film according to claim 1 is used in the lithium metal negative electrode protection process of sulfide-based all-solid-state battery, it is characterized in that, described LBO compound also has dry method preparation process. 4. A kind of LBO self-supporting film according to claim 1 is used for the lithium metal negative _{electrode protection process of sulfide-based all-solid-state battery, it is characterized in that, in described S1, the molar ratio of H BO 3 and} LiOH is 1 : (1-3). 5. A kind of LBO self-supporting film according to claim 1 is used for the lithium metal negative electrode protection process of sulfide-based all-solid-state battery, it is characterized in that, in described S1, solvent is ethylene carbonate, propylene carbonate, carbonic acid Dimethyl ester, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl formate, methyl acetate, methyl butyrate, ethyl propionate, 2-methyltetrahydrofuran, 1,3-dioxane One or more of pentane and 4-methyl-1,3-dioxolane. 6. A kind of LBO self-supporting film according to claim 1 is used in the lithium metal negative electrode protection process of sulfide-based all-solid-state battery, it is characterized in that, in described S3, rare gas is argon. 7. A kind of LBO self-supporting film according to claim 1 is used in the lithium metal negative electrode protection process of sulfide-based all-solid-state battery, it is characterized in that, in described S3, the coating method is spin coating or blade coating.

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