CN113659197A

CN113659197A - Solid electrolyte with interface modification layer and preparation method and application thereof

Info

Publication number: CN113659197A
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: 2021-11-16
Anticipated expiration: 2041-07-26
Also published as: CN113659197B

Abstract

The invention 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. The preparation method of the solid electrolyte with the 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-dimensional material and the polymer binder in N-methylpyrrolidone, heating and stirring to uniformly mix the two-dimensional material and the polymer binder to obtain a mixed solution, dripping, spraying or spin-coating the mixed solution on the surface of a solid electrolyte, and drying to obtain an interface modified layer. The invention is beneficial to improving interface contact, reducing interface impedance and inhibiting the decomposition of the NASICON type solid electrolyte while isolating the electrolyte and the lithium negative electrode through the mixing of the two-dimensional material and the polymer, thereby improving the performance of the all-solid-state lithium metal battery.

Description

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

Technical Field

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

Background

Solid electrolytes have been extensively studied so far, and the classes include perovskite oxides, garnet-type oxides, sulfide-based solid electrolytes, and the like. Among various solid electrolytes, NASICON-type electrolytes, which have high ionic conductivity and lower cost, are recognized as one of the alternatives to liquid electrolytes. Although the NASICON-type solid electrolyte has the above-described advantages, its development is limited by its instability with lithium metal negative electrodes. Lithium metal has extremely strong reducibility and can react with Ti in NASICON type solid electrolyte⁴⁺And Ge⁴⁺Reaction, a high conductivity phase is formed at the interface between lithium metal and the NASICON-type solid electrolyte, which transforms its interface from a single-ion conductor interface to an electron-ion mixed conducting interface, while the high electron conductivity of the interface accelerates the formation of the interface phase and lithium dendrites, resulting in the failure of the interface and the corresponding cell. Meanwhile, the solid-solid contact interface between the electrolyte and the electrode in the all-solid-state lithium battery is an insufficient contact interface, which causes overlarge local current density of the battery in the circulation process, thereby influencing the service life of the battery.

Disclosure of Invention

The invention aims to provide a solid electrolyte with an interface modification layer, which has good cycle performance and safety, and a preparation method and application thereof, aiming at the defects of the prior art.

The solid electrolyte 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 includes Li_1+xAl_xTi_2-x(PO₄)₃(0≤x≤0.5)，Li₁₊ _xAl_xGe_2-x(PO₄)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 10 nm-50 μm.

A preparation method of a solid electrolyte with an 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-dimensional material and the polymer binder in a solvent, heating and stirring 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 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-methylpyrrolidone.

The two-dimensional material adopted by the invention is a semiconductor material, has the characteristics of low electronic conductivity and high ionic conductivity, and meets the requirement that the interface modification layer is a single-ion conductor. Meanwhile, the addition of the polymer is beneficial to adjusting the viscosity of the spin-coating liquid, so that the thickness of the modification layer is adjusted. Besides, the polymer material as a flexible material is beneficial to improving the mechanical property of the modification layer and obtaining better interface contact. By mixing the two-dimensional material and the polymer, the electrolyte and the lithium negative electrode are isolated, and meanwhile, the interface contact is improved, the interface impedance is reduced, the decomposition of the NASICON type solid electrolyte is inhibited, and the performance of the all-solid-state lithium metal battery is improved.

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

Drawings

FIG. 1 is a flow chart of a NASICON type solid electrolyte interfacial modification method of an embodiment of the present application;

FIG. 2 is a scanning electron microscope image of an interface of a solid electrolyte modified by a two-dimensional material molybdenum disulfide according to an embodiment of the present invention;

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

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

Example 1

Lithium iron phosphate is adopted as a positive electrode material, Li_1.4Al_0.4Ti_1.6(PO₄)₃As an electrolyte sheet, metallic lithium was used as a negative electrode. According to the following steps: weighing molybdenum disulfide and polyvinylidene fluoride according to the mass ratio of 1, dissolving the molybdenum disulfide and the polyvinylidene fluoride in NMP, heating and stirring the mixture at 90 ℃ for 12 hours, coating the obtained mixture on the surface of an electrolyte sheet by a spin coating method, wherein the coating parameters are set to operate at 1000rpm for 20s, and the coating parameters are set to operate at 5000rpm for 50 s. After the coating was completed, the obtained sheet was dried in a vacuum oven at 75 ℃ for 12 hours. Referring to FIG. 2, a modified layer with a thickness of 1 μm is finally obtained. And assembling the obtained electrolyte sheet, the anode and the cathode which are prepared in the earlier stage into a CR2032 battery. Referring to fig. 3, the capacity is maintained at 128.4mAh/g after constant current discharge for 200 cycles at 1C, the capacity retention rate is 79.8%, and good cycle performance is shown, when tested at 60 ℃.

Example 2

Lithium iron phosphate is adopted as a positive electrode material, Li_1.5Al_0.5Ge_1.5(PO₄)₃As an electrolyte sheet, metallic lithium was used as a negative electrode. According to the following steps: weighing molybdenum disulfide and polyvinylidene fluoride according to the mass ratio of 1, dissolving the molybdenum disulfide and the polyvinylidene fluoride in NMP, heating and stirring the mixture at 90 ℃ for 12 hours, coating the obtained mixture on the surface of an electrolyte sheet by a spin coating method, wherein the coating parameters are set to operate at 1000rpm for 20s, and the coating parameters are set to operate at 5000rpm for 50 s. After the coating was completed, the obtained sheet was dried in a vacuum oven at 75 ℃ for 12 hours. And assembling the obtained electrolyte sheet, the anode and the cathode which are prepared in the earlier stage into a CR2032 battery. The test at 60 ℃ shows that the capacity is kept at 118.7mAh/g after constant current discharge for 220 circles at 1C, the capacity retention rate is 83.9 percent, and the good cycle performance is shown.

Example 3

Lithium iron phosphate is adopted as a positive electrode material, Li_1.4Al_0.4Ti_1.6(PO₄)₃As an electrolyte sheet, metallic lithium was used as a negative electrode. Carrying out atmosphere ball milling pretreatment on the black phosphorus crystal to obtain black phosphorus crystal powder, wherein the mass ratio of the black phosphorus crystal powder to the solid is 1: weighing black phosphorus and polyvinylidene fluoride according to the mass ratio of 1, dissolving the black phosphorus and the polyvinylidene fluoride in NMP, heating and stirring the mixture at 90 ℃ for 12 hours, coating the obtained mixture on the surface of an electrolyte sheet by a spin coating method, and setting the coating parameters to operate for 20s at 1000rpm and 50s at 5000 rpm. After the coating was completed, the obtained sheet was dried in a vacuum oven at 75 ℃ for 12 hours. And assembling the obtained electrolyte sheet, the anode and the cathode which are prepared in the earlier stage into a CR2032 battery. The test at 60 ℃ shows that the capacity is kept at 136.7mAh/g after 190 circles of constant current discharge at 1C, the capacity retention rate is 86.1 percent, and the good cycle performance is shown.

Example 4

Lithium iron phosphate is adopted as a positive electrode material, Li_1.4Al_0.4Ti_1.6(PO₄)₃As an electrolyte sheet, metallic lithium was used as a negative electrode,

transition metal carbides or nitrides (MXenes) are the main component of the finish. According to the following steps: 1, dissolving the transition metal carbide or nitride and polyvinylidene fluoride in NMP, heating and stirring at 90 ℃ for 12h, coating the obtained mixture on the surface of an electrolyte sheet by a spin coating method, wherein the coating parameters are set to operate at 1000rpm for 20s and 5000rpm for 50 s. After the coating was completed, the obtained sheet was dried in a vacuum oven at 75 ℃ for 12 hours. And assembling the obtained electrolyte sheet, the anode and the cathode which are prepared in the earlier stage into a CR2032 battery. The test at 60 ℃ shows that the capacity is maintained at 136.2mAh/g after the constant current discharge of 175 circles at 1C, the capacity retention rate is 89.7 percent, and the good cycle performance is shown.

Example 5

Lithium iron phosphate is adopted as a positive electrode material, Li_1.5Al_0.5Ge_1.5(PO₄)₃As an electrolyte sheet, metal lithium is used as a negative electrode, and tungsten disulfide is used as a main component of a modification layer. According to the following steps: weighing tungsten disulfide and polyvinylidene fluoride according to the mass ratio of 1,and dissolved in NMP, heated and stirred at 90 ℃ for 12h, and the resulting mixture was coated on the surface of the electrolyte sheet by the spin coating method with the coating parameters set to run at 1000rpm for 20s and 5000rpm for 50 s. After the coating was completed, the obtained sheet was dried in a vacuum oven at 75 ℃ for 12 hours. And assembling the obtained electrolyte sheet, the anode and the cathode which are prepared in the earlier stage into a CR2032 battery. The test at 60 ℃ shows that the capacity is kept at 124.7mAh/g after 195 circles of constant current discharge at 1C, the capacity retention rate is 80.6 percent, 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 invention have been described in detail by way of illustration, it will be understood by those skilled in the art that the foregoing is illustrative only and is not limiting of the scope of the invention, as various modifications or additions may be made to the specific embodiments described and substituted in a similar manner by those skilled in the art without departing from the scope of the invention as defined in the appending claims. It should be understood by those skilled in the art that any modifications, equivalents, improvements and the like made to the above embodiments in accordance with the technical spirit of the present invention are included in the scope of the present invention.

Claims

1. A solid state electrolyte having an interfacial modification layer, characterized by: the interface modification layer comprises a two-dimensional material and a polymer binder, and is coated on the surface of the solid electrolyte.

2. The solid electrolyte having an interface modification layer according to claim 1, wherein: the solid electrolyte is a NASICON type solid electrolyte.

3. The solid electrolyte having an interface modification layer according to claim 2, wherein: the NASICON-type solid electrolyte comprises Li_1+xAl_xTi_2-x(PO₄)₃(0≤x≤0.5)，Li_1+xAl_xGe_2-x(PO₄)₃(0≤x≤0.5)。

4. A solid-state electrolyte having an interface modification layer according to any one of claims 1 to 3, wherein: the mass ratio of the two-dimensional material to the polymer binder is (1-50): 5.

5. the solid electrolyte having an interface modification layer according to claim 4, wherein: the two-dimensional material comprises one or more of molybdenum disulfide, tungsten disulfide, transition metal carbide or nitride, and black phosphorus.

6. The solid electrolyte having an interface modification layer according to claim 5, wherein: the polymer binder comprises one or more of polyvinylidene fluoride, polyethylene oxide, polyethylene lactone and polyacrylonitrile.

7. A solid-state electrolyte having an interface modification layer according to any one of claims 1 to 3, wherein: the thickness of the interface modification layer is 10 nm-50 μm.

8. A method for producing a solid electrolyte having an interface modification layer according to any one of claims 1 to 7, characterized in that: weighing a two-dimensional material and a polymer binder according to a certain mass ratio, dissolving the two-dimensional material and the polymer binder in a solvent, heating and stirring the two-dimensional material and the polymer binder to uniformly mix the two-dimensional material and the polymer binder to obtain a mixed solution, dripping, spraying or spin-coating the mixed solution on the surface of a solid electrolyte, and drying the solid electrolyte to obtain the solid electrolyte with an interface modification layer.

9. The method of claim 8, wherein the solid electrolyte comprises an interfacial modification layer, and the method comprises: the heating temperature is 60-110 ℃, the heating time is 5-48 h, and the solvent comprises N-methyl pyrrolidone.

10. A battery comprising the solid-state electrolyte having an interface modification layer as claimed in any one of claims 1 to 7.