Lithium ion conducting lithium sulphur oxynitride thin film, and a process for the preparation thereof

Abstract

The disclosure herein relates to a lithium ion conducting electrolyte. This electrolytic material has improved ionic conductivity. The material disclosed herein is an amorphous compound of the formula LixSMwOyNz wherein x is between approximately 0.5 and 3, y is between 1 and 6, z is between 0.1 and 1, w is less than 0.3 and M is an element selected from B, Ge, Si, P, As, Cl, Br, I, and combinations thereof. The material can be prepared in the form of a thin film. The electrolyte material can be used in microbatteries and elctronic systems.

Description

Claims

1. A material consisting of an amorphous compound having the atomic composition LixSMwOyNz in which x is between approximately 0.5 and approximately 3, y is between approximately 1 and approximately 6, z is between 0.1 and 1, w is less than 0.3 and M represents an element selected from the group consisting of B, Ge, Si, P, As, Cl, Br, I, and combinations thereof.

2. The material as claimed in claim 1, which is in the form of a film deposited on a substrate.

3. The material as claimed in claim 2, wherein the substrate is selected from the group consisting of aluminum, silicon, carbon, stainless steel, a positive electrode material, and a negative electrode material.

4. The material as claimed in claim 1, wherein x is between approximately 0.5 and approximately 2, y is between approximately 1 and approximately 4, and z is between 0.1 and 1 and w=0.

5. The material as claimed in claim 1, wherein w is not zero.

6. A method for preparing a material as claimed in claim 2, comprising producing a deposit on a substrate by radiofrequency magnetron sputtering, wherein deposition is carried out under the following conditions: the plasma used for cathode sputtering is a gas comprising nitrogen and optionally oxygen, argon, or combinations thereof, with the minimum nitrogen content being 30 at %; andthe target used for cathode sputtering is a target comprising at least 80% by weight of Li2SO4 in the crystallized form.

7. The method as claimed in claim 6, wherein the substrate is selected from the group consisting of aluminum, silicon, carbon, stainless steel, a positive electrode material and a negative electrode material.

8. The method as claimed in claim 6, wherein the plasma is a gaseous mixture comprising 0 to 20% argon or oxygen.

9. The method as claimed in claim 6, wherein the the target consists of Li2SO4.

10. The method as claimed in claim 6, wherein the the target comprises at most 20 at % of at least one additive selected from the group consisting of compounds acting as glass network formers, compounds acting as vitrification modifiers, and compounds that are the source of lithium ions.

11. The method as claimed in claim 10, wherein the glass network-forming compound is selected from the group consisting of oxides, sulfides and nitrides of boron, germanium, silicon, arsenic or phosphorus.

12. The method as claimed in claim 10, wherein the compounds that are the source of lithium are lithium halides.

13. The method as claimed in claim 10, wherein the compounds acting as vitrification-modifiers are selected from the group consisting of oxides, sulfides and nitrides of lithium.

14. The method as claimed in claim 11, wherein the respective proportions of Li2SO4 and an additive or additives are chosen so that the atomic composition of the mixture formed of Li2SO4 and the additive or additives is LixSMwOyNz, wherein x is between approximately 0.5 and approximately 3, y is between approximately 1 and approximately 6, z is between 0.1 and 1, w is less than 0.3 and M represents an element selected from the group consisting of B, Ge, Si, P, As, Cl, Br, I, and combinations thereof.

15. An electrochemical device comprising an electrolyte placed between a negative electrode and a positive electrode, wherein the electrolyte is a film of material as claimed in claim 2.

16. The material as claimed in claim 3, wherein the positive electrode material is TiS2 or LiCoO2, and the negative electrode material is metallic lithium or a lithium alloy.

17. The method as claimed in claim 7, wherein the positive electrode material is TiS2 or LiCoO2 and the negative electrode material is metallic lithium or a lithium alloy.