Trapping and catalytic conversion of polysulfides by kirkendall effect built hollow NiCo2S4 nano-prisms for advanced sulfur cathodes in Li–S battery

Abstract

To address the problems of low active utilization and fast capacity decay in practical application of lithium–sulfur (Li–S) battery, an effective and widely used strategy is incorporating polar materials into sulfur cathode to tune the redox reaction of polysulfides in recent years. Herein, a hollow nano-prism structured bimetallic sulfide (NiCo2S4) built by kirkendall effect is proposed to trap and catalyze conversion of polysulfides. Beneficial from the strong interaction and super electrocatalytic effect for the intermediates of sulfur reduction, the NiCo2S4 incorporated in sulfur cathode can significantly ease the shuttle effect, decrease the activation energy and dynamically accelerates the transformation of the polysulfides. As expected, together with the high conductivity, hollow structure and compositional superiorities, the sulfur cathode with NiCo2S4 for Li–S battery exhibits apparently enhanced sulfur utilization and improved cycling performance that preserves super low capacity fading rate of 0.05% per cycle after 800 cycles at 1 C. This work has guiding significance in the design of a sulfur cathode for advanced Li–S battery.