Boron-Doped Dinickel Phosphide to Enhance Polysulfide Conversion and Suppress Shuttling in Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are promising for next-generation high-energy energy storage systems. However, the slow reaction kinetics render mobile polysulfides hardly controlled, yielding shuttling effects and eventually damaging Li metal anodes. To improve the cyclability of Li–S batteries, high-efficiency catalysts are desired to accelerate polysulfide conversion and suppress the shuttling effect. Herein, we studied a doping system with Ni₂P and Ni₂B as the end members and found a B-doped Ni₂P catalyst that demonstrates high activity for Li–S batteries. As anionic dopants, B demonstrates an interesting reverse electron transfer to P and tunes the electronic structure of Ni₂P dramatically. The resultant B-doped Ni₂P exhibits short Ni–B bonds and strong Ni–S interaction, and the electron donation of B to P further enhances the adsorption of polysulfide on catalysts. The S–S bonds of polysulfides were activated appropriately, therefore decreasing a low energy barrier for conversion reactions.