To Promote the Catalytic Conversion of Polysulfides Using Ni–B Alloy Nanoparticles on Carbon Nanotube Microspheres under High Sulfur Loading and a Lean Electrolyte

Despite their high theoretical energy density, the application of lithium–sulfur batteries is seriously hindered by the polysulfide shuttle and sluggish kinetics, especially with high sulfur loading and under low electrolyte usage. Herein, to facilitate the conversion of lithium polysulfides, nickel–boron (Ni–B) alloy nanoparticles, dispersed uniformly on carbon nanotube microspheres (CNTMs), are used as sulfur hosts for lithium–sulfur batteries. It is demonstrated that Ni–B alloy nanoparticles can not only anchor polysulfides through Ni–S and B–S interactions but also exhibit high electrocatalytic capability toward the conversion of intermediate polysulfide species. In addition, the intertwined CNT microspheres provide an additional conductive scaffold in response to the fast electrochemical redox. The enhanced redox kinetics is beneficial to improve the specific capacity and cycling stability of the sulfur cathode, based on the fast conversion of lithium polysulfides and effective deposition of the final sulfide products. Conclusively, the S/Ni–B/CNTM composite delivers a high specific capacity (1112.7 mAh gs–1) along with good cycle performance under both high sulfur loading (8.3 mg cm–2) and a lean electrolyte (3 μL mgs–1). Consequently, this study opens up a path to design new sulfur hosts toward lithium–sulfur batteries.