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

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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.