Enhancing moisture and electrochemical stability of the Li5.7PS4.7Cl1.3 electrolyte by boron nitride coating for all-solid-state lithium metal batteries

Weak water stability and lithium reactivity are two major stability issues of sulfide solid-state electrolytes (SSEs) for all-solid-state lithium metal batteries. Here, we report on nano-sized boron nitride (BN)-coated Li5.7PS4.7Cl1.3 (BN@LPSC1.3) sulfide SSE, which exhibits reduced H2S emission and improved ionic conductivity retention after relative humidity 1.2%–1.5% ambient condition exposure. Furthermore, BN can partially react with lithium metal to create stable Li3N, resulting in BN@LPSC1.3 showing reduced reactivity against lithium metal and a higher critical current density of 2.2 mA/cm2. The Li/BN@LPSC/Li symmetrical battery also shows considerably greater stability for >2,000 h at a current density of 0.1 mA/cm2. Despite the high cathode mass loading of 13.38 mg/cm2, the LiNi0.8Co0.1Mn0.1O2/BN@LPSC1.3/Li all-solid-state lithium metal battery achieves 84.34% capacity retention even after 500 cycles at 0.1 C and room temperature (25°C).