High-Entropy Oxide Nanofibers as Catalytic Host Promising High Volumetric Capacity of Sulfur-Based Composites for Lithium–Sulfur Batteries

The exploration of the appropriate sulfur host with favorable catalytic activity and high density is important to enhance the volumetric energy density of lithium–sulfur (Li–S) batteries. In this work, high-entropy oxide (HEO) of (Ni0.2Co0.2Mn0.2Cu0.2Zn0.2)WO4 (HE-CWO) nanofibers is fabricated as the sulfur host for the first time. The multiple metal cations in the single-phase structure of HE-CWO nanofibers enable strong chemical interaction with soluble lithium polysulfides and fast conversion kinetics from polysulfides to the final discharge product of Li2S2/Li2S. Therefore, the S/HE-CWO composite exhibits a good rate capacity with 656.3 mA h g–1 at 5C rate and desirable cycling stability with a slow fading rate of 0.080% per cycle for 500 cycles at 1C rate. Moreover, the tap density of the S/HE-CWO composite reaches 1.98 g cm–3, nearly twice as high as that of the S/CNT composite (0.96 g cm–3), leading to a high volumetric capacity of 1795.3 mA h cm–3–composite. This work affords a promising strategy for improving the volumetric energy density and electrochemical performance of Li–S batteries..