Temperature-dependent compatibility study on halide solid-state electrolytes in solid-state batteries

Abstract

All-solid-state lithium batteries (ASSLBs) have attracted much attention owing to their high safety and energy density compared to conventional organic electrolytes. However, the interfaces between solid-state electrolytes and electrodes retain some knotty problems regarding compatibility. Among the various SSEs investigated in recent years, halide SSEs exhibit relatively good interfacial compatibility. The temperature-dependent interfacial compatibility of halide SSEs in solid-state batteries is investigated by thermal analysis using simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD). Halide SSEs, including rock-salt-type Li₃InCl₆ and anti-perovskite-type Li₂OHCl, show good thermal stability with oxides LiCoO₂, LiMn₂O₄, and Li₄Ti₅O₁₂ up to 320 °C. Moreover, anti-perovskite-type Li₂OHCl shows a chemical reactivity with other battery materials (eg., LiFePO₄, LiNi_0.8Co_0.1Mn_0.1O₂, Si-C, and Li_1.3Al_0.3Ti_1.7(PO₄)₃) at 320°C, which reaches the melting point of Li₂OHCl. It indicated that Li₂OHCl has relatively high chemical reactivity after melting. In contrast, rock-salt-type Li₃InCl₆ shows higher stability and interfacial compatibility. This work delivers insights into the selection of suitable battery materials with good compatibility for ASSLBs.