Double catalysis of Co9Se8-Ni3Se4 heterogeneous dual-chamber core-shell Achieves high conversion of polysulfides.

Abstract

Achieving efficient catalytic conversion of lithium polysulfides is a key way to improve kinetics in lithium-sulfur (Li-S) batteries. However, due to the limited nature of the catalyst interface, it is difficult to achieve a high conversion rate of LiPSs in one step. A novel heterogeneous dual-chamber core-shell nanocatalyst (Co₉Se₈-Ni₃Se₄@PC) is described here, which efficiently accommodates sulfur and provides a heterogeneous dual catalytic interface like a two-stage "filter". The dual guarantee provides a rapid and high-ratio catalytic conversion of LiPSs. Through in-situ Raman experiments and theoretical analysis, it has been proved that the dual-chamber multi-stage catalytic structure can promote the efficient conversion of LiPSs and good sulfur species reversibility. The Co₉Se₈-Ni₃Se₄@PC cathode provides an initial specific capacity of 923mAh/g at 2C, and the average capacity decay rate after 800 cycles is only 0.048 %. This work provides new ideas for designing new nanocatalysts in lithium-sulfur systems and insights into achieving multi-stage catalysis in structural design.