Modifying Li2B12H12 to become a highly electrochemically stable solid electrolyte

Abstract

Metal hydridoborates are promising electrolyte materials for next generation batteries. However, most hydridoborates show low ionic conductivity at room temperature and relatively poor electrochemical stability towards high-voltage cathodes. In this work, modifications to the Li₂B₁₂H₁₂ solid electrolyte are undertaken by ball-milling, partial thermal decomposition and hydration. Impacts of morphological and structural changes on their ionic conductivity and electrochemical stability are analysed and discussed. A solid-state electrolyte synthesised by partial thermal decomposition of Li₂B₁₂H₁₂ at 380 °C is reported to exhibit remarkable oxidative stability, greater than 6 V (vs. Li⁺/Li), and an increase by nearly 2 orders of magnitude in Li⁺ conductivity at 30 °C compared to the pristine material. Herein, partial thermal decomposition is proposed as a new approach to improve the electrochemical properties of metal hydridoborate-based solid electrolytes.