Built-in Electric Field Within CoSe-FeSe Heterostructure for Enhanced Sulfur Reduction Reaction in Li-S Batteries.

The conversion of LiS to LiS is the most important and slowest rate-limiting step in the complex sulfur reduction reaction (SRR) for Li-S batteries, the adjustment of which can effectively inhibit the notorious "shuttle effect". Herein, a CoSe-FeSe heterostructure embedded in 3D N-doped nanocage as a modified layer on commercial separator is designed (CoSe-FeSe@NC//PP). The CoSe-FeSe heterostructure forms a built-in electric field at the two-phase interface, which leads to the optimized adsorption force on polysulfides and the accelerated reaction kinetics for LiS-LiS evolution.