CN-116247309-B - Method for modifying interface between lithium negative electrode and solid electrolyte

Abstract

The invention discloses a method for modifying the interface between a lithium negative electrode and a solid electrolyte, which is characterized in that the lithium negative electrode is prepared by a blanking method with a simple process, and ionic liquid is applied to the interface between a positive electrode and the solid electrolyte and the interface between the negative electrode and the solid electrolyte when a battery is assembled. The invention solves the problems of high technical requirement of the existing molten lithium preparation of the negative electrode, easy pollution of the surface of the ceramic plate, short circuit of the battery and the like, and the battery can obtain excellent performance by only adopting a blanking method to prepare the negative electrode and carrying out interface modification on the negative electrode, has simple process, can realize batch production and has excellent market potential.

Inventors

• MA ZENGSHENG
• AN BAOGUANG
• XIE WENJING
• WU YAPING

Assignees

• 湘潭大学

Dates

Publication Date

20260505

Application Date

20230301

Claims (3)

1. 1. A method for modifying the interface between a lithium negative electrode and a solid electrolyte, which is characterized in that ionic liquid is applied to the interface between a positive electrode and the solid electrolyte and the interface between the negative electrode and the solid electrolyte when a battery is assembled; The negative electrode is a lithium negative electrode; The solid electrolyte is a garnet type solid electrolyte ceramic wafer; the preparation method of the ionic liquid comprises the following steps: Adding LiTFSI according to 1.2-2 mol/L by taking PY 13 NTF 2 as the volume of the ionic liquid, uniformly mixing, and adding 10-15 vol% of commercial carboxylate electrolyte by taking the volume of the PY 13 NTF 2 as the volume of the ionic liquid; the carboxylate electrolyte is 1mol/L LiClO4, and the volume ratio of the solvent MF to MA is=1:1.
2. 2. The method for modifying an interface between a lithium anode and a solid electrolyte according to claim 1, wherein the battery is composed of a positive electrode, a negative electrode and a solid electrolyte, and the negative electrode is manufactured by punching.
3. 3. The method for modifying a lithium anode and solid electrolyte interface according to claim 1 or 2, wherein the preparation method of the garnet-type solid electrolyte ceramic sheet is as follows: (1) Preparing lithium hydroxide monohydrate, lanthanum oxide, zirconium oxide and aluminum oxide according to stoichiometric ratio, adding a solvent, and then performing ball milling; (2) Sintering the powder obtained by ball milling in the step (1) for 4-8 hours at 800-1000 ℃ to obtain cubic-phase garnet-type solid electrolyte, namely LLZAO ceramic powder; (3) Tabletting LLZAO ceramic powder obtained in the step (2) to obtain green bodies, burying the green bodies by LLZAO ceramic powder obtained in the step (2), calcining at 1000-1400 ℃ for 6-10h, and polishing to obtain LLZAO ceramic sheets.

Description

Method for modifying interface between lithium negative electrode and solid electrolyte Technical Field The invention relates to an all-solid-state lithium ion battery, in particular to a method for modifying an interface between a lithium negative electrode and a solid electrolyte. Background The traditional rechargeable lithium battery uses an organic liquid electrolyte or a gel polymer electrolyte, is easy to leak and burn under certain conditions, has larger potential safety hazard, and meanwhile, has a more complex battery structure, and limits the further improvement of energy density. The electrolyte is replaced by the solid electrolyte, so that the safety and the energy density of the battery are expected to be greatly improved. Among the many solid electrolytes, li 7La3Zr2O12 (LLZO) of garnet structure is attracting attention because of advantages such as high conductivity and good electrochemical stability. Compared with other solid electrolytes, LLZO solid electrolytes have higher hardness, point-to-point rigid contact with electrode materials and large interface resistance, and researchers wet the interface of the positive electrode side by using liquid electrolytes with high ion conductivity to convert point-to-point discontinuous solid/solid contact into better surface contact, so that the interface resistance is reduced. Lithium metal is considered to be a key material for realizing a high energy density battery due to its own outstanding properties, and is used for the negative electrode of all-solid-state batteries. When lithium is used as a negative electrode of the LLZO solid electrolyte, the problem of high interface impedance caused by solid/solid contact is solved by adopting a method of melting lithium, but the process requirement of melting lithium is high, the molten lithium needs to be operated in a glove box in the whole process, lithium is easy to adhere around a ceramic plate, polishing is also carried out in the glove box, the operation is difficult, the surface pollution of the ceramic plate is easy to cause, if the polishing is not clean, the battery is short-circuited, the contact angle of the molten lithium on the surface of the LLZO solid electrolyte is large, the electrolyte shows lithium-thinning property, and meanwhile, lithium dendrite growth is easy to be caused by non-uniformity of interface contact, so that the battery structure is damaged. Disclosure of Invention Aiming at the problems existing in the existing method for preparing the negative electrode by using molten lithium, the invention provides a method for modifying the interface between the lithium negative electrode and the solid electrolyte, the negative electrode is prepared by using a blanking method with simple process, and the interface between the negative electrode is modified by using ionic liquid, so that good performance is obtained. The technical scheme of the invention is as follows: A method for modifying the interface between lithium negative electrode and solid electrolyte features that when the battery is assembled, ionic liquid is applied to both the interface between positive electrode and solid electrolyte and the interface between negative electrode and solid electrolyte. Further, the battery is composed of a positive electrode, a negative electrode and a solid electrolyte, wherein the negative electrode is prepared by a blanking method. Further, the negative electrode is preferably a lithium negative electrode. Further, the solid electrolyte is preferably a garnet-type solid electrolyte ceramic sheet. Further, the preparation method of the ionic liquid comprises the following steps: Adding lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) according to the volume of N-propyl-N-methylpyrrolidine bis (trifluoromethanesulfonyl) imide ionic liquid (PY 13NTF2) and 1.2-2mol/L, uniformly mixing, and adding 10-15 vol% of commercial carboxylate electrolyte according to the volume of PY 13NTF2 ionic liquid. Further, the commercial carboxylate electrolyte can be selected from 1mol/L LiClO 4, and the volume ratio of the solvent MF (methyl formate): MA (methyl acetate) =1:1. Further, the preparation method of the garnet-type solid electrolyte ceramic wafer comprises the following steps: (1) Preparing lithium hydroxide monohydrate, lanthanum oxide, zirconium oxide and aluminum oxide according to stoichiometric ratio, adding a solvent, and then performing ball milling; (2) Sintering the powder obtained by ball milling in the step (1) for 4-8 hours at 800-1000 ℃ to obtain cubic-phase garnet-type solid electrolyte, namely LLZAO ceramic powder; (3) Tabletting LLZAO ceramic powder obtained in the step (2) to obtain green bodies, burying the green bodies by LLZAO ceramic powder obtained in the step (2), calcining at 1000-1400 ℃ for 6-10h, and polishing to obtain LLZAO ceramic sheets. The invention has the beneficial effects that: According to the invention, the specific ionic liquid is applied to the i