Strong interface effect on Ni2P/CeOx nanoparticles for high performance lithium-sulfur batteries

Abstract

The disordered structure of electrocatalysts exhibits enhanced catalytic activity. The integration of the disordered structure catalyst into the conductive catalyst is an effective strategy for optimizing the properties of the active site, which is beneficial for enhancing the inhibition of the shuttle effect and the redox kinetics of sulfur species. Herein, an amorphous cerium oxide (CeO_x) introduced to the surface of nickel phosphides (Ni₂P) is prepared to serve as an electrocatalyst and barrier layer in lithium-sulfur batteries for the first time. The appropriate adsorption capacity of Ni₂P/CeO_x for soluble sulfur species due to the formation of the multi-active adsorbed sites (Ni-S, Ce-S, O-Li) effectively suppress the shuttle effect. The electronic interaction between CeO_x and Ni₂P achieves the construction of built-in electric field by the bridge effect exerted of O atoms. The enhanced surface wettability, smaller internal resistances and the synergy between the stronger adsorption capacity of Ni₂P for LiPSs and the Li₂S deposition/decomposition on the CeO_x surface accelerate the redox kinetics. The designed Ni₂P/CeO_x applied as the interlayer exhibits a long cycle stability (capacity decay of 0.03% per cycle after 2000 cycles at 1 C) and a higher capacity of 655.3 mAh g^-1 after 700 cycles at 0.5 C.