On the formation and properties of amorphous and crystalline Li3-yBay/2OCl electrolytes

Abstract

All-solid-state batteries (ASSBs) have potential to provide higher specific energy, higher power, and longer cycle life than Li-ion batteries (LIBs) for continuously increasing demands of high-performance rechargeable batteries with intrinsic safety. However, one of the barriers for successful design and fabrication of ASSBs is the lack of solid-state electrolytes (SSEs) that can meet multi-functional requirements for ASSBs. To address this issue, the present study investigates hydrothermal synthesis of amorphous and crystalline Ba-doped Li3OCl solid electrolytes and develops the understanding of the relationships between the synthesis conditions and electrochemical properties of the products. It is shown that the formation of an amorphous/crystalline Ba-doped Li3OCl mixture with little hydroxide impurities depends strongly on the hydrothermal reaction temperature, drying temperature, Ba concentration, and rate of removing OH− and H+ ions as steam from water solvated Ba-doped Li3OCl. The key to generate amorphous Li3OCl-based electrolytes with high ionic conductivities (7.65 × 10−3 S/cm) at room temperature is to create non-equilibrium synthesis conditions such as the one identified in this study. The understanding developed in this study will offer critical guidelines for synthesizing amorphous and crystalline Li3OCl-based electrolytes with superior electrochemical properties for ASSBs reliably and reproducibly in the near future.