Honeycomb porous N-doped carbon synergized with ultrafine Ni2P electrocatalyst for boosting polysulfide conversion in lithium–sulfur batteries

Abstract

The intractable shuttle effect and sluggish redox kinetics are major impediments to the practical application of lithium–sulfur (Li–S) batteries. Herein, ultrafine Ni2P nanodots decorated porous N-doped carbon (Ni2P@PNC) is successfully constructed by a novel chelate-phosphating strategy and employed as sulfur host to realize effective suppression of shuttle effect and enhancement of redox kinetics. Owing to the strong polarity and catalytic activity, the Ni2P electrocatalyst synergized with PNC conductive skeleton can efficiently promote chemisorption and catalytic conversion of the electrochemical intermediate lithium polysulfides. In addition, Ni2P@PNC can effectively decrease the transformation barrier and enhance the precipitation capability for the discharge end-product Li2S. As a result, the assembled Li–S cells with high sulfur-loading Ni2P@PNC/S cathode under low electrolyte/sulfur ratio deliver remarkable electrochemical performances in terms of high initial discharge capacity of 1350 mA h g–1, excellent rate capability of 695 mA h g–1 at 2.0 C, as well as outstanding cycle stability with an ultralow capacity decay rate of 0.021% per cycle over 1000 cycles at 2.0 C. Such the inspiring architectonic of multifunctional catalyzing-type sulfur hosts paves a new path for the development of high-performance Li−S batteries.