Surface reconstruction for a spinel-type electrocatalyst towards fast sulfur conversion in advanced lithium-sulfur batteries

• A surface-reconstructed spinel-phase catalyst was developed via Mn atoms doping. • The catalyst has a distinctive active surface characterized by Co/O deficiency. • A robust chemical interaction between the catalyst and polysulfides was identified. • Li-S battery with this catalyst delivers a good electrochemical performance . Lithium-sulfur (Li-S) batteries are recognized as a promising energy storage solution due to their high theoretical specific capacity and energy density. However, the full potential of Li-S batteries has not been realized, primarily due to challenges such as the shuttle effect and slow reaction kinetics. The incorporation of appropriate electrocatalysts presents a viable approach to address these issues, so this study introduces a surface-reconstructed spinel-phase catalyst, referred to as MCO-x, which is anticipated to significantly enhance the electrochemical performance of Li-S batteries. It has been observed that the introduction of a minor amount of Mn atoms results in the surface reconstruction of the spinel-phase Co 3 O 4 catalyst, thereby creating a distinctive active surface characterized by cobalt/oxygen deficiency. Additionally, the presence of multivalent cobalt ions (Co 3+ /Co 2+ ) generated through charge compensation imparts a robust chemical interaction between the MCO-x catalyst and lithium polysulfides . This interaction mitigates irreversible losses and facilitates the conversion of sulfur species. When the MCO-0.2 catalyst is integrated with porous carbon as a sulfur host material in a Li-S battery configuration, the resulting cell exhibits a high reversible capacity (1300.4 mAh g −1 at 0.1C) and commendable cycle stability within 500 cycles at 1C, with a low fading rate of 0.08 % per cycle. Notably, even with a high sulfur areal loading of 4.2 mg cm −2 , the corresponding areal capacity achieves 4.4 mAh cm −2 at 0.1C. These critical performance metrics underscore the significance of the surface reconstruction strategy in informing the design and application of electrocatalysts for Li-S batteries.