Ni12P5 nanoparticles bound on graphene sheets for advanced lithium–sulfur batteries

Abstract

Lithium–sulfur batteries (LSBs) have been regarded as potential energy storage devices by virtue of their high theoretical capacity, natural abundance of materials and low cost. However, the notorious shuttle effect and sluggish reaction kinetics are still significant challenges for further development. Herein, Ni₁₂P₅ nanoparticles are devised and grown on a reduced graphene oxide (Ni₁₂P_5@rGO) framework via a self-template and recrystallization–self-assembly strategy, as the modifier for separators in LSBs for the first time. The support of rGO for Ni₁₂P₅ nanoparticles could solve the self-aggregation problem. Ni₁₂P₅ nanoparticles not only effectively adsorb polysulfides by polar interaction, but also supply active sites to ameliorate the kinetics of the redox reaction of sulfur. Consequently, when a sulfur-containing commercial acetylene black material (70 wt% sulfur content) is used as the cathode composite without complicated fabrication or surface modification, an LSB with Ni₁₂P₅@rGO modified separator shows excellent cycling stability and a capacity degradation of 0.074% per cycle at the current density of 1 C for 500 cycles. When the areal mass of sulfur further increases to 3.5 mg cm⁻², the capacity degradation is only 0.071% per cycle at 150 cycles. This study could accelerate the application of phosphides in LSBs.