Improving sulfur transformation of lean electrolyte lithium–sulfur battery using nickel nanoparticles encapsulated in N-doped carbon nanotubes

Efficient redox reactions of lean electrolyte lithium–sulfur (Li–S) batteries highly rely on rational catalyst design. Herein, we report an electrocatalyst based on N-doped carbon nanotubes (CNT)-encapsulated Ni nanoparticles (Ni@NCNT) as kinetics regulators for Li–S batteries to propel the polysulfide-involving multiphase transformation. Moreover, such a CNT-encapsulation strategy greatly prevents the aggregation of Ni nanoparticles and enables the extraordinary structural stability of the hybrid electrocatalyst, which guarantees its persistent catalytic activity on sulfur redox reactions. When used as a modified layer on a commercial separator, the Ni@NCNT interlayer contributes to stabilizing S cathode and Li anode by significantly retarding the shuttle effect. The corresponding batteries with a 3.5 mg cm⁻² sulfur loading achieve the promising cycle stability with ∼85% capacity retention at the electrolyte/sulfur ratios of 5 and 3 μL mg⁻¹. Even at a high loading of 12.2 mg cm⁻², the battery affords an areal capacity of 7.5 mA h cm⁻².