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Atomic Layer Deposited Lithium Silicates as Solid-State Electrolytes for All-Solid-State Batteries
journal contribution
posted on 2017-07-27, 00:00 authored by Biqiong Wang, Jian Liu, Mohammad Norouzi
Banis, Qian Sun, Yang Zhao, Ruying Li, Tsun-Kong Sham, Xueliang SunDevelopment
of solid-state electrolyte (SSE) thin films is a key toward the fabrication
of all-solid-state batteries (ASSBs). However, it is challenging for
conventional deposition techniques to deposit uniform and conformal
SSE thin films in a well-controlled fashion. In this study, atomic
layer deposition (ALD) was used to fabricate lithium silicate thin
films as a potential SSE for ASSBs. Lithium silicates thin films were
deposited by combining ALD Li2O and SiO2 subcycles
using lithium tert-butoxide, tetraethylorthosilane,
and H2O as precursors. Uniform and self-limiting growth
was achieved at temperatures between 225 and 300 °C. X-ray absorption
spectroscopy analysis disclosed that the as-deposited lithium silicates
were composed of SiO4 tetrahedron structure and lithium
oxide as the network modifier. X-ray photoelectron spectroscopy confirmed
the chemical states of Li in the thin films were the same with that
in standard lithium silicate. With one to one subcycle of Li2O and SiO2 the thin films had a composition close to Li4SiO4 whereas one more subcycle of Li2O delivered a higher lithium content. The lithium silicate thin film
prepared at 250 °C exhibited an ionic conductivity of 1.45×
10–6 S cm–1 at 373 K. The high
ionic conductivity of lithium silicate was due to the higher lithium
concentration and lower activation energy.