CoOx nanoparticles loaded on carbon spheres with synergistic effects for effective inhibition of shuttle effect in Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries, as one of the new energy storage batteries, show immense potential due to their high theoretical specific capacity and theoretical energy density. However, there are still some problems to be solved, among which the shuttle effect of lithium polysulfides is one extremely serious issue with respect to the industrial application of Li–S batteries. Rational design of electrode materials with effective catalytic conversion ability is an effective route to accelerate the conversion of lithium polysulfides (LiPSs). Herein, considering the adsorption and catalysis of LiPSs, CoO_x nanoparticles (NPs) loaded on carbon sphere composites (CoO_x/CS) were designed and constructed as cathode materials. The CoO_x NPs obtained, with ultralow weight ratio and uniform distribution, consist of CoO, Co₃O₄, and metallic Co. The polar CoO and Co₃O₄ enable chemical adsorption towards LiPSs through Co–S coordination, and the conductive metallic Co can improve electronic conductivity and reduce impedance, which is beneficial for ion diffusion at the cathode. Based on these synergistic effects, the CoO_x/CS electrode exhibits accelerated redox kinetics and enhanced catalytic activity for conversion of LiPSs. Consequently, the CoO_x/CS cathode delivers improved cycling performance, with an initial capacity of 980.8 mA h g⁻¹ at 0.1C and a reversible specific capacity of 408.4 mA h g⁻¹ after 200 cycles, along with enhanced rate performance. This work provides a facile route to construct cobalt-based catalytic electrodes for Li–S batteries, and promotes understanding of the LiPSs conversion mechanism.