Fabrication of amorphous LiPON, LiAlGePO, and GeSn films in low-temperature plasma sputtering process for all-solid-state Li+-ion battery

Abstract

Plasma-sputtered amorphous films for all-solid-state Li+-ion batteries are investigated. In LiPON electrolyte films, the amount of N incorporated into LiPO films is controlled by the sputtering discharge gas. Ionic conductivity increases with increasing N2 gas proportion in Ar/N2 discharge, reaching a maximum of 2.7 × 10−6 S cm−1 at Li2.39PO3.71N0.13. In amorphous LiAlGePO electrolyte films, the amounts of Al and Ge incorporated into LiPO films are controlled in a combinatorial approach using two-source co-sputtering. The P/Ge ratio varies over a wide range from 23.3 to 1.61 at the radial substrate positions, and the highest ionic conductivity of 4.32 × 10−5 S cm−1 is achieved at Li4.80Al0.80Ge1.16P3O13.1. We evaluate all-solid-state Li+-ion batteries fabricated using the developed amorphous LiPON electrolyte and GeSn anode films, where GeSn films with about 50 nm nanograins are fabricated by high-gas-pressure sputtering at 500 mTorr. A maximum capacity of 2.86 μAh cm−2 is attained for all-solid state Li+-ion battery.