A method for modifying the anode interface of a solid-state lithium battery

Abstract

The present invention discloses a method for modifying the anode interface of a solid-state lithium battery. The method comprises the following steps: Step 1, polishing the surface of a solid electrolyte sheet; Step 2, modifying the surface of the solid electrolyte sheet polished in Step 1 with a colloidal solution containing metal-oxo hybrid clusters to obtain a solid electrolyte sheet modified with metal-oxo hybrid clusters; Step 3, compounding a lithium negative electrode with the solid electrolyte sheet modified with metal-oxo hybrid clusters in Step 2 and heating at 180-350 °C for 15-60 min to obtain a solid electrolyte / lithium anode interface modified with metal-oxo hybrid clusters. The operation method of the present invention is simple, reliable, time-saving and efficient, does not require the use of sophisticated instruments with complex operations, and has excellent effects, and can be widely promoted and applied on a large scale.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state batteries and relates to a method for modifying the anode interface of a solid-state lithium battery. Background Art

[0002] Since solid-state lithium batteries (SSLB) do not have an electrolyte solution and a separator, the anode can directly use lithium metal, and the solid electrolyte has the characteristics of non-flammability, non-volatility, non-leakage, good insulation, and a wide operating temperature range. Therefore, it breaks through the limitations of traditional liquid lithium-ion batteries in terms of energy density and safety. Among the numerous solid electrolytes currently under research, garnet-type solid electrolytes represented by LLZO have excellent thermal stability, high lithium-ion conductivity, good electrochemical stability, and stability to lithium anodes, showing excellent comprehensive performance. However, poor wettability leads to poor solid-solid interface contact between the electrolyte and the electrode, and uneven interface electric field distribution leads to the growth of lithium dendrites, which hinders its practical application. Summary of the Invention

[0003] Aiming at the problems of high interfacial impedance and lithium dendrite growth and piercing at the interface between the garnet-type solid electrolyte and the lithium anode, the present invention provides a method for modifying the anode interface of a solid-state lithium battery.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for modifying the anode interface of a solid-state lithium battery includes the following steps:

[0006] Step 1, polishing the surface of the solid electrolyte sheet, where:

[0007] The solid electrolyte is at least one of garnet-type solid electrolytes Li 7-x La3Zr 2-x M x O 12 and its doped compounds, where M is Nb or Ta, and 0 ≤ x < 2;

[0008] Step 2, modifying a colloidal solution containing metal-oxo clusters on the surface of the solid electrolyte sheet polished in Step 1 to obtain a solid electrolyte sheet modified with metal-oxo clusters, where:

[0009] The method of modifying the colloidal solution containing metal-oxo clusters on the surface of the solid electrolyte sheet polished in Step 1 is to coat the colloidal solution containing metal-oxo clusters on the solid electrolyte sheet polished in Step 1;

[0010] The coating method is at least one of smearing, drop coating, and spin coating;

[0011] In the colloidal solution containing metal-oxygen clusters, the mass fraction of the organic solution is 0.05-0.5%, the organic solvent is one of ethylene glycol dimethyl ether, N,N-dimethylpyrrolidone, and N,N-dimethylformamide, and the solute is metal-oxygen clusters, which can be titanium-oxygen hybrid clusters, zinc-oxygen hybrid clusters or molybdenum-oxygen hybrid clusters with different skeletons;

[0012] The mass of the colloidal solution containing metal-oxygen hybrid clusters used on the surface of the solid electrolyte sheet per unit area is 0.01-0.5 mg / cm 2 ;

[0013] Step 3: Composite the lithium negative electrode with the solid electrolyte sheet modified by metal-oxygen hybrid clusters in step 2, and heat at 180-350 °C for 15-60 min to obtain a solid electrolyte / lithium anode interface modified by metal-oxygen hybrid clusters.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. Since metal-oxygen hybrid clusters are rich in organic functional groups, they can be uniformly dispersed in organic reagents to form a colloid, meeting the conditions for colloidal self-assembly: a. hard sphere repulsion; b. uniform particle size; c. van der Waals force between particles; d. the system can undergo a destabilization process. Through simple drop coating, direct evaporation destabilization is used, and the self-assembly property of the colloid is utilized to form a uniform thin intermediate layer on the electrolyte surface. Then, an isotropic amorphous mixed conductive layer is formed by in-situ thermal reaction with molten lithium. It should be noted that this simple and reliable wet chemical method can control the thickness of the intermediate layer by changing the amount of the drop-coated colloid, which is conducive to exploring the optimal conditions under different systems. In addition, the in-situ chemical reaction realizes the close contact between the electrode and the electrolyte. The amorphous intermediate layer is isotropic, which not only provides an effective ion transport path for Li + but also guides a uniform electric field at the interface, realizing the uniform deposition / stripping of lithium metal on the electrode surface and suppressing the growth of lithium dendrites.

[0016] 2. The operation method of the present invention is simple, reliable, time-saving and efficient. It does not require the use of sophisticated instruments with complex operations, and has excellent effects, and can be widely promoted and applied on a large scale. Description of the Drawings

[0017] Figure 1 Impedance diagram of the symmetric cell without {Ti 52 O 74} cluster modification in the comparative example;

[0018] Figure 2 Impedance diagram of the symmetric cell modified by {Ti 52 O 74} cluster in Example 1;

[0019] Figure 3 For the long - cycle performance graph of the symmetric battery modified by the {Ti 52 O 74} cluster in Example 1. Detailed implementation mode

[0020] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0021] Example 1

[0022] A method for modifying the anode interface of a solid - state lithium battery includes the following steps:

[0023] Step 1: Grind the two surfaces of the solid - state electrolyte sheet Li 6.5 La3Zr 1.5 Ta 0.5 O 12 .

[0024] Step 2: Spin - coat 3 μl of a DME solution of {Ti 52 O 74} clusters with a mass fraction of 0.2% on the surface of the ground solid - state electrolyte sheet with a diameter of 12 mm to obtain a solid - state electrolyte sheet modified by {Ti 52 O 74} clusters.

[0025] Step 3: Place lithium sheets on the upper and lower surfaces of the solid - state electrolyte sheet modified by {Ti 52 O 74} clusters to build a solid - state lithium symmetric battery, and then place it on a heating table and heat at 300 °C for 20 min to obtain a solid - state electrolyte / lithium anode interface modified by {Ti 52 O 74} clusters.

[0026] Example 2

[0027] A method for modifying the anode interface of a solid - state lithium battery includes the following steps:

[0028] Step 1: Grind the two surfaces of the solid - state electrolyte sheet Li 6.5 La3Zr 1.5 Ta 0.5 O 12 .

[0029] Step 2: Spin - coat 2.5 μl of a DME solution of {Ti 32 O 16} The NMP solution of the clusters was coated on the surface of the polished solid electrolyte sheet with a diameter of 12 mm using a spin coater to obtain a solid electrolyte sheet modified with {Ti 32 O 16} clusters;

[0030] Step 3: Lithium sheets were placed on the upper and lower surfaces of the solid electrolyte sheet modified with {Ti 32 O 16} clusters to construct a solid-state lithium symmetric battery, which was then placed on a heating table and heated at 280 °C for 20 min to obtain a solid electrolyte / lithium anode interface modified with {Ti 32 O 16} clusters.

[0031] Example 3

[0032] A method for modifying the anode interface of a solid-state lithium battery, comprising the following steps:

[0033] Step 1: The two surfaces of the solid electrolyte sheet Li 6.5 La3Zr 1.5 Ta 0.5 O 12 were polished;

[0034] Step 2: 4 μl of a DMF solution of {ZnO} 34 clusters with a mass fraction of 0.15% was coated on the surface of the polished solid electrolyte sheet with a diameter of 12 mm using a spin coater to obtain a solid electrolyte sheet modified with {ZnO} 34 clusters;

[0035] Step 3: Lithium sheets were placed on the upper and lower surfaces of the solid electrolyte sheet modified with {ZnO} 34 clusters to construct a solid-state lithium symmetric battery, which was then placed on a heating table and heated at 320 °C for 30 min to obtain a solid electrolyte / lithium anode interface modified with {ZnO} 34 clusters.

[0036] Example 4

[0037] A method for modifying the anode interface of a solid-state lithium battery, comprising the following steps:

[0038] Step 1: The two surfaces of the solid electrolyte sheet Li 6.5 La3Zr 1.5 Nb 0.5 O 12 were polished;

[0039] Step 2: 5 μl of a solution of {Mo 10 O 18The DMF solution of the clusters was coated on the surface of the polished solid electrolyte sheet with a diameter of 12 mm using a spin coater to obtain a solid electrolyte sheet modified with {Mo 10 O 18} clusters;

[0040] Step 3: Lithium sheets were placed on the upper and lower surfaces of the solid electrolyte sheet modified with {Mo 10 O 18} clusters to build a solid-state lithium symmetric battery, which was then placed on a heating table and heated at 350 °C for 30 min to obtain a solid electrolyte / lithium anode interface modified with {Mo 10 O 18} clusters.

[0041] Comparative Example

[0042] The difference between this comparative example and Example 1 is that: Lithium sheets were placed on the upper and lower surfaces of the unmodified Li 6.5 La3Zr 1.5 Ta 0.5 O 12 solid electrolyte sheet to assemble a solid-state lithium symmetric battery.

[0043] Figure 2 Comparison with Figure 1 shows that the impedance of the symmetric battery modified with {Ti 52 O 74} clusters is significantly reduced. Figure 3 It shows that the symmetric battery modified with {Ti 52 O 74} clusters has excellent long-cycle performance and good ability to resist lithium dendrite growth.

Claims

1. A method for modifying the anode interface of a solid-state lithium battery, characterized in that The method comprises the following steps: Step 1. Polish the surface of the solid electrolyte sheet. The solid electrolyte is at least one of garnet-type solid electrolytes Li 7-x La3Zr 2-x M x O 12 and its doped compounds, where M is Nb or Ta, and 0 ≤ x < 2; Step 2: Modify the surface of the solid electrolyte sheet polished in Step 1 with the colloidal solution containing metal-oxo clusters to obtain a solid electrolyte sheet modified with metal-oxo clusters, where the mass of the colloidal solution containing metal-oxo clusters is 0.01 - 0.5 mg / cm 2 , and the metal-oxo clusters are {Ti 52 O 74} clusters, {Ti 32 O 16} clusters, {ZnO} 34 clusters or {Mo 10 O 18} clusters; Step 3: Composite the lithium anode with the solid electrolyte sheet modified by the metal-oxo hybrid cluster in Step 2, and heat at 180-350 °C for 15-60 min to obtain a solid electrolyte / lithium anode interface modified by the metal-oxo hybrid cluster.

2. The modification method of the anode interface of the solid-state lithium battery according to claim 1, characterized in that In Step 2, the method for modifying the surface of the solid electrolyte sheet polished in Step 1 with the colloidal solution containing the metal-oxo hybrid cluster is to coat the colloidal solution containing the metal-oxo hybrid cluster on the solid electrolyte sheet polished in Step 1.

3. The modification method of the anode interface of the solid-state lithium battery according to claim 2, characterized in that The coating method is at least one of smearing, drop coating, and spin coating.

4. The method for modifying the anode interface of a solid-state lithium battery according to claim 1 or 2, characterized in that In the colloidal solution containing the metal-oxo hybrid cluster, the mass fraction of the organic solution is 0.05-0.5%.

5. The modification method of the anode interface of the solid-state lithium battery according to claim 4, characterized in that The organic solution is one of ethylene glycol dimethyl ether, N,N-dimethylpyrrolidone, and N,N-dimethylformamide.

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