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

The intractable shuttle effect and sluggish redox kinetics are major impediments to the practical application lithium-sulfur (Li-S) batteries. Herein, ultrafine Ni2P nanodots decorated porous N-doped carbon (Ni2P@PNC) 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 ac-tivity, 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 ca-pacity 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 archi-tectonic of multifunctional catalyzing-type sulfur hosts paves a new path for the development of high-performance Li -S batteries.

Automated summary

A novel chelate-phosphating strategy was used to construct ultrafine Ni2P nanodots decorated porous N-doped carbon (Ni2P@PNC) as a sulfur host, effectively suppressing the shuttle effect and enhancing the redox kinetics in lithium-sulfur batteries. The synergistic effect of Ni2P electrocatalyst and PNC conductive skeleton promoted the adsorption and catalytic conversion of lithium polysulfides. The assembled Li-S cells with Ni2P@PNC/S cathode exhibited remarkable electrochemical performances, including high initial discharge capacity, excellent rate capability, and outstanding cycle stability.