Flower-like ZnO modified with BiOI nanoparticles as adsorption/catalytic bifunctional hosts for lithium-sulfur batteries

Abstract Due to the high specific capacity and energy density, lithium-sulfur battery is regarded as a potential energy storage conversion system. However, the serious shuttle effect and the sluggish electrochemical reaction kinetics impede the practical use of lithium-sulfur battery. In the interests of breaking through the above knotty problems, herein we propose to use the polar flower-like ZnO modified by BiOI nanoparticles as bifunctional host with catalytic and adsorption ability for polysulfides in lithium-sulfur battery. It can be found that this adsorption/catalytic host integrates the functions of adsorption and mutual catalytic conversion of polysulfides, in which the polar flower-like ZnO can effectively capture the polysulfides through strong polar-polar interaction, simultaneously the BiOI nanoparticles can accelerate the mutual conversion of polysulfides to Li2S through reducing the activation energy and conversion energy barrier required for the electrochemical reaction. As a result, under a sulfur loading of 2.5 mg cm−2, the lithium-sulfur battery with ZnO/BiOI/CNT/S as cathode reveals a considerable initial specific capacity of 1267 mAh g−1 at a current density of 0.1C. Even the current density increased to 1C, the capacity can reach as 873.4 mAh g−1, together with a good capacity retention of 67.1% after 400 cycles. Therefore, after systematically study the positive effects of the flower-like ZnO modified by catalytic BiOI nanoparticles on the adsorption and catalytic conversion of polysulfides, this work provides a new idea for the development and application of high-performance lithium-sulfur batteries.