CN113659197B

CN113659197B - Solid electrolyte with interface modification layer and preparation method and application thereof

Info

Publication number: CN113659197B
Application number: CN202110845370.5A
Authority: CN
Inventors: 袁硕果; 黄灿; 孙国栋; 靳洪允; 侯书恩
Original assignee: China University of Geosciences
Current assignee: China University of Geosciences
Priority date: 2021-07-26
Filing date: 2021-07-26
Publication date: 2023-08-18
Anticipated expiration: 2041-07-26
Also published as: CN113659197A

Abstract

The application discloses a solid electrolyte with an interface modification layer, and a preparation method and application thereof. The interface modification layer comprises a two-dimensional material and a polymer binder, and is coated on the surface of the solid electrolyte. A preparation method of a solid electrolyte with an interface modification layer comprises the following steps: weighing a two-dimensional material and a polymer binder according to a certain mass ratio, dissolving the two materials in N-methyl pyrrolidone, heating and stirring the mixture to uniformly mix the two materials to obtain a mixed solution, dripping, spraying or spin-coating the mixed solution on the surface of the solid electrolyte, and drying the mixed solution to obtain the interface modification layer. According to the application, through mixing the two-dimensional material and the polymer, the electrolyte and the lithium cathode are isolated, meanwhile, the interface contact is improved, the interface impedance is reduced, and the decomposition of the NASICON type solid electrolyte is inhibited, so that the performance of the all-solid lithium metal battery is improved.

Description

Solid electrolyte with interface modification layer and preparation method and application thereof

Technical Field

The application relates to the technical field of solid-state batteries, in particular to a solid-state electrolyte with an interface modification layer, and a preparation method and application thereof.

Background

Solid electrolytes have been widely studied so far, and the category includes perovskite oxides, garnet-type oxides, sulfide-based solid electrolytes, and the like. Of the various solid electrolytes, NASICON type electrolytes, which have high ionic conductivity and lower cost characteristics, are considered as one of the alternatives to liquid electrolytes. Although NASICON-type solid-state electrolytes have the above-described advantages, their instability with lithium metal anodes limits their development. The lithium metal has extremely strong reducibility and can be matched with NASICOTi in N-type solid electrolyte ⁴⁺ And Ge (Ge) ⁴⁺ And the reaction forms a high-conductivity phase on the interface between the lithium metal and the NASICON solid electrolyte, so that the interface is converted from a single ion conductor interface to an electron-ion mixed conductive interface, and meanwhile, the high electron conductivity of the interface accelerates the formation of the interface phase and lithium dendrite, thereby causing the failure of the interface and a corresponding battery. Meanwhile, a solid-solid contact interface between an electrolyte and an electrode in an all-solid-state lithium battery is an insufficient contact interface, so that the local current density of the battery is overlarge in the circulation process, and the service life of the battery is further influenced.

Disclosure of Invention

The application aims at providing a solid electrolyte with an interface modification layer, a preparation method and application thereof, wherein the solid electrolyte has good cycle performance and safety, and aims at overcoming the defects in the prior art.

The solid electrolyte provided with the interface modification layer comprises a two-dimensional material and a polymer binder, and the interface modification layer is coated on the surface of the solid electrolyte.

Further, the solid electrolyte is a NASICON type solid electrolyte.

Further, the NASICON type solid electrolyte comprises Li _1+x Al _x Ti _2-x (PO ₄ ) ₃ (0≤x≤0.5)，Li ₁₊ _x Al _x Ge _2-x (PO ₄ ) ₃ (0≤x≤0.5)。

Further, the mass ratio of the two-dimensional material to the polymer binder is (1-50): 5.

further, the two-dimensional material comprises one or more of molybdenum disulfide, tungsten disulfide, transition metal carbide or nitride and black phosphorus.

Further, the polymer binder comprises one or more of polyvinylidene fluoride, polyethylene oxide, polyethylene lactone and polyacrylonitrile.

Further, the thickness of the interface modification layer is 10nm to 50 μm.

The preparation method of the solid electrolyte with the interface modification layer comprises the steps of weighing a two-dimensional material and a polymer binder according to a certain mass ratio, dissolving the two materials in a solvent, heating and stirring the two materials to uniformly mix the two materials to obtain a mixed solution, dripping, spraying or spin-coating the mixed solution on the surface of the solid electrolyte, and drying the mixed solution to obtain the solid electrolyte with the interface modification layer.

Further, the heating temperature is 60-110 ℃, the heating time is 5-48 h, and the solvent comprises N-methyl pyrrolidone.

The two-dimensional material adopted by the application is a semiconductor material, has the characteristics of low electron conductivity and high ion conductivity, and meets the requirement that the interface modification layer needs to be a single ion conductor. Meanwhile, the addition of the polymer is helpful for adjusting the viscosity of the spin coating liquid, so that the thickness of the modification layer is adjusted. In addition, the polymer material is used as a flexible material, so that the mechanical property of the modification layer is improved, and better interface contact is obtained. Through the mixing of the two-dimensional material and the polymer, the electrolyte and the lithium cathode are isolated, meanwhile, the interface contact is improved, the interface impedance is reduced, and the decomposition of the NASICON type solid electrolyte is inhibited, so that the performance of the all-solid lithium metal battery is improved.

The method has the advantages of wide raw materials, easy implementation and remarkable effect, and is suitable for industrial production.

Drawings

FIG. 1 is a flow chart of a method for interface modification of a NASICON type solid state electrolyte according to an embodiment of the present application;

FIG. 2 is a photograph of a solid electrolyte interface scanning electron microscope after modification of a two-dimensional material molybdenum disulfide in an embodiment of the application;

fig. 3 is a 1C rate cycle life curve (60 ℃ constant temperature test) of the solid-state battery in the example of the application.

Detailed Description

The following are specific embodiments of the present application and the technical solutions of the present application will be further described with reference to the accompanying drawings, but the present application is not limited to these embodiments.

Example 1

Lithium iron phosphate is used as a positive electrode material, li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ As an electrolyte sheet, metallic lithium was used as a negative electrode. According to the following steps of 1:1, molybdenum disulfide and polyvinylidene fluoride were weighed in mass ratio, dissolved in NMP, heated and stirred at 90 ℃ for 12 hours, and the obtained mixture was coated on the surface of an electrolyte sheet by a spin coating method, and the coating parameters were set to 1000rpm for 20s and 5000rpm for 50s. After the coating was completed, the resulting sheet was dried in a vacuum oven at 75℃for 12 hours. Referring to fig. 2, a modified layer having a thickness of 1 μm was finally obtained. And assembling the obtained electrolyte sheet with a positive electrode and a negative electrode prepared in advance to form the CR2032 battery. Referring to FIG. 3, the capacity is kept at 128.4mAh/g after 200 times of constant current discharge at 1C, the capacity retention rate is 79.8%, and the cycle performance is good.

Example 2

Lithium iron phosphate is used as a positive electrode material, li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ As an electrolyte sheet, metallic lithium was used as a negative electrode. According to the following steps of 1:1, molybdenum disulfide and polyvinylidene fluoride were weighed in mass ratio, dissolved in NMP, heated and stirred at 90 ℃ for 12 hours, and the obtained mixture was coated on the surface of an electrolyte sheet by a spin coating method, and the coating parameters were set to 1000rpm for 20s and 5000rpm for 50s. After the coating was completed, the resulting sheet was dried in a vacuum oven at 75℃for 12 hours. And assembling the obtained electrolyte sheet with a positive electrode and a negative electrode prepared in advance to form the CR2032 battery. Tested at 60 ℃, the capacity is kept at 118.7mAh/g after 220 circles of constant-current discharge at 1C, the capacity retention rate was 83.9%, and good cycle performance was exhibited.

Example 3

Lithium iron phosphate is used as a positive electrode material, li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ As an electrolyte sheet, metallic lithium was used as a negative electrode. Performing atmosphere ball milling pretreatment on the black phosphorus crystal to obtain black phosphorus crystal powder according to the following ratio of 1:1, and dissolving in NMP, heating and stirring at 90 ℃ for 12 hours, and coating the obtained mixture on the surface of an electrolyte sheet by a spin coating method, wherein the coating parameters are set to be 20s at 1000rpm and 50s at 5000 rpm. After the coating was completed, the resulting sheet was placed at 75 ℃Is dried in a vacuum drying oven for 12 hours. And assembling the obtained electrolyte sheet with a positive electrode and a negative electrode prepared in advance to form the CR2032 battery. Tested at 60 ℃, the capacity is kept at 136.7mAh/g after 190 times of constant-current discharge at 1C, the capacity retention rate was 86.1%, and good cycle performance was exhibited.

Example 4

Lithium iron phosphate is used as a positive electrode material, li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ As an electrolyte sheet, metallic lithium as a negative electrode,

transition metal carbides or nitrides (mxnes) are the main component of the finishing layer. According to the following steps of 1:1, a transition metal carbide or nitride and polyvinylidene fluoride were weighed in mass ratio, dissolved in NMP, heated and stirred at 90 ℃ for 12 hours, and the resulting mixture was coated on the surface of an electrolyte sheet by a spin coating method with the coating parameters set to 1000rpm for 20s and 5000rpm for 50s. After the coating was completed, the resulting sheet was dried in a vacuum oven at 75℃for 12 hours. And assembling the obtained electrolyte sheet with a positive electrode and a negative electrode prepared in advance to form the CR2032 battery. The capacity is kept at 136.2mAh/g after 175 circles of constant-current discharge at 1C under the test of 60 ℃, the capacity retention rate is 89.7%, and the good cycle performance is shown.

Example 5

Lithium iron phosphate is used as a positive electrode material, li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ As an electrolyte sheet, metallic lithium was used as a negative electrode, and tungsten disulfide was used as a main component of the modified layer. According to the following steps of 1:1, tungsten disulfide and polyvinylidene fluoride were weighed in mass ratio, dissolved in NMP, heated and stirred at 90 ℃ for 12 hours, and the obtained mixture was coated on the surface of an electrolyte sheet by a spin coating method, and the coating parameters were set to 1000rpm for 20s and 5000rpm for 50s. After the coating was completed, the resulting sheet was dried in a vacuum oven at 75℃for 12 hours. And assembling the obtained electrolyte sheet with a positive electrode and a negative electrode prepared in advance to form the CR2032 battery. The capacity is kept at 124.7mAh/g after 195 times of constant-current discharge at 1C under the test of 60 ℃, the capacity retention rate is 80.6%, and the good cycle performance is shown.

The above is not relevant and is applicable to the prior art.

While certain specific embodiments of the present application have been described in detail by way of example, it will be appreciated by those skilled in the art that the foregoing examples are provided for the purpose of illustration only and are not intended to limit the scope of the application, and that various modifications or additions and substitutions to the described specific embodiments may be made by those skilled in the art without departing from the scope of the application or exceeding the scope of the application as defined in the accompanying claims. It should be understood by those skilled in the art that any modification, equivalent substitution, improvement, etc. made to the above embodiments according to the technical substance of the present application should be included in the scope of protection of the present application.

Claims

1. A lithium battery comprising a solid state electrolyte having an interface modifying layer, characterized by: the interface modification layer comprises a two-dimensional material and a polymer binder, is coated on the surface of the solid electrolyte and is positioned between the solid electrolyte and the lithium negative electrode;

the solid electrolyte is NASICON type solid electrolyte;

the two-dimensional material includes molybdenum disulfide.

2. A lithium battery comprising a solid state electrolyte having an interface modifying layer as claimed in claim 1, wherein: the NASICON type solid electrolyte comprises Li _x1+ Al _x Ti _x2- (PO ₄ ) ₃ (0≤x≤0.5)，Li _x1+ Al _x Ge _x2- (PO ₄ ) ₃ (0≤x≤0.5)。

3. A lithium battery comprising a solid state electrolyte with an interface modifying layer according to claim 1 or 2, characterized in that: the mass ratio of the two-dimensional material to the polymer binder is (1-50): 5.

4. a lithium battery comprising a solid state electrolyte having an interface modifying layer as claimed in claim 1, wherein: the polymer binder comprises one or more of polyvinylidene fluoride, polyethylene oxide and polyacrylonitrile.

5. A lithium battery comprising a solid state electrolyte with an interface modifying layer according to claim 1 or 2, characterized in that: the thickness of the interface modification layer is 10 nm-50 mu m.

6. A method for producing a solid electrolyte having an interface modification layer in a lithium battery according to any one of claims 1 to 5, characterized in that: weighing a two-dimensional material and a polymer binder according to a certain mass ratio, dissolving the two materials in a solvent, heating and stirring the mixture to uniformly mix the two materials to obtain a mixed solution, dripping, spraying or spin-coating the mixed solution on the surface of the solid electrolyte, and drying the mixed solution to obtain the solid electrolyte with the interface modification layer.

7. The method for preparing a solid electrolyte with an interface modification layer in a lithium battery according to claim 6, wherein: the heating temperature is 60-110 ℃, the heating time is 5-48 h, and the solvent comprises N-methyl pyrrolidone.

8. A solid electrolyte with an interface-modifying layer prepared by the preparation method of claim 6 or 7.