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

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, LiNi0.8Co0.1Mn0.1O2, Si-C, and Li1.3Al0.3Ti1.7(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.