Joshi, Ashok V.; Jatkar, Arun D.; Sholette, William P.;

Phosphorus-containing solid state electrolyte

An electrolyte for a solid state lithium electrochemical cell comprising an interdiffused mixture of PI.sub.3 or BI.sub.3 and LiI and optionally Al.sub.2 O.sub.3 and cells containing such electrolyte.

We claim:

1. A solid state electrolyte comprising an interdiffused mixture of, in mole percent, about 0.4% to about 16% of a material selected from the group of boron triiodide and phosphorus triiodide, about 33% to about 99% lithium iodide and up to about 60% alumina.

2. A solid state electrolyte as in claim 1 containing phosphorus triiodide.

3. A solid state electrolyte as in claim 1 comprising, in mole percent, about 0.8% to about 12% phosphorus triiodide.

4. A solid state electrolyte as in claim 1 containing boron triiodide and alumina.

5. A solid state electrolyte as in claim 1 which contains, in mole percent, about 50% to about 65% lithium iodide, about 1% to about 1.5% of material selected from the group of boron triiodide and phosphorus triiodide and about 35% to about 45% alumina.

6. A solid state electrolyte comprising an interdiffused mixture of about 1 to about 16 mole percent phosphorus triiodide with the balance being essentially lithium iodide.

7. A solid state electrolyte as in claim 6 wherein the mole percent of phosphorus triiodide is in the range of about 2% to 12%.

8. A solid state electrochemical cell having a lithium anode, a solid state electrolyte comprising an interdiffused mixture of, in mole percent, about 0.4% to about 16% phosphorus triiodide, about 33% to about 99% lithium iodide and up to about 60% alumina and a compatible cathode.

9. A solid state electrochemical cell as in claim 8 wherein the electrolyte contains, in mole percent, about 0.8% to about 12% phosphorus triiodide.

10. A solid state electrochemical cell as in claim 8 wherein the electrolyte contains, in mole percent, about 63% lithium iodide, about 1.3% phosphorus triiodide and about 35% alumina.

11. A solid state electrochemical cell as in claim 8 wherein the electrolyte contains, in mole percent, about 50% to about 65% lithium iodide, about 1% to about 1.5% of a material from the group of phosphorus triiodide and boron triiodide and about 35% to about 45% of alumina.