Ultrathin Lithium Aluminate Nanoflake-Inlaid Sulfur as a Cathode Material for Lithium–Sulfur Batteries with High Areal Capacity

Abstract

Direct Utilization of commercial sulfur as a cathode material is ideal for the bulk production of high-energy-density lithium–sulfur (Li–S) batteries. However, due to large ion-diffusion length, commercial sulfur suffers from low practical capacity. To achieve adequate capacity with long-term cyclability using the commercial sulfur-based cathodes, we introduce ultrathin lithium aluminate (LiAlO2) nanoflakes as polysulfide immobilizers with excellent Li+ ion conductivity. The ultrathin LiAlO2 nanoflake-inlaid sulfur cathode exhibits high areal capacity with extremely stable cycling performance. At a current rate of 0.2C, our cathode delivered a high areal capacity of 4.86 mA h cm–2 during the first cycle and retains 4.75 mA h cm–2 after 100 cycles. At a high current rate of 3C, the cathode retains the areal capacity of 2.52 mA h cm–2 after 500 cycles, with an extremely low capacity decay rate of 0.02% per cycle. In situ Raman spectroscopy studies coupled with the chronoamperometry technique reveal that LiAlO2 nanoflakes catalyze the redox kinetics in the Li–S batteries. This work shows a promising strategy to directly utilize commercial sulfur powder in practical Li–S batteries.