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.