US Patent 7410730 Thin film battery and electrolyte therefor

A solid amorphous electrolyte composition for a thin-film battery. The electrolyte composition includes a lithium phosphorus oxynitride material containing an aluminum ion dopant wherein the atomic ratio of aluminum ion to phosphorus ion (Al/P) in the electrolyte ranges greater than zero up to about 0.5. The composition is represented by the formula:LitPxAlyOuNvSw,where 5x+3y=5, 2u+3v+2w=5+t, t ranges from about 2.9 to about 3.3, x ranges from about 0.94 to about 0.85, y ranges from about 0.094 to about 0.26, u ranges from about 3.2 to about 3.8, v ranges from about 0.13 to about 0.46, and w ranges from zero to about 0.2. Thin film batteries containing such electrolyte films have less tendency to fail prematurely.