Understanding the Role of Nano‐Aluminum Oxide in All‐Solid‐State Lithium‐Sulfur Batteries

Abstract Aluminum oxide (Al 2 O 3 ) is a well‐known electrolyte filler for stabilizing the Li‐metal (Li 0 ) anode in all‐solid‐state Li 0 ‐based batteries. However, its strong interactions with lithium polysulfides (PS) hinder the direct application of Al 2 O 3 ‐added electrolytes in all‐solid‐state lithium‐sulfur batteries (ASSLSBs). Herein, the role of Al 2 O 3 in ASSLSBs both as electrolyte filler and cathode additive is studied. The combination of Al 2 O 3 ‐added electrolyte and Al 2 O 3 ‐added S 8 cathode with optimum cell configuration could deliver an unprecedented discharge capacity of 0.85 mAh cm −2 (C/10, 30 cycles) for polymer‐based ASSLSBs. These results suggest that the rational incorporation of Al 2 O 3 can lead simultaneously to PS anchoring and Li 0 anode stabilizing benefits from the ceramic filler, thus improving the electrochemical performance of ASSLSBs.