An electrochemically switched ion exchange α-ZrP/PPy film as a synergistically catalytic and anchoring material towards lithium-sulfur battery design

Abstract

The commercial application of lithium-sulfur (Li-S) batteries is largely hindered by their insufficient rate performance and cycle stability because of the shuttle effect and sluggish kinetic conversion of lithium polysulfides (LiPSs). Herein, an electrochemically switched ion exchange film of heterostructured α-zirconium phosphate/polypyrrole (α-ZrP/PPy), which combined the virtues of conductive PPy with highly adsorptive α-ZrP was investigated to be able to synergistically restrain the shuttle effect and facilitate the redox reaction kinetics of LiPSs by employing the density functional theory (DFT) calculation. The mechanism of redox reaction and the microcosmic-properties of electron were explored in detail. Adsorption calculations revealed that the captured LiPSs by α-ZrP/PPy with a moderate adsorption ability and the electrocatalytic activity of the anchoring material would effectively restrain the shuttle effect and accelerate the decomposition of LiPSs back to sulfur during charging process. Furthermore, α-ZrP and PPy provided unique ion migration channel and electronic transfer channel, respectively, and the rapid redox reactions were induced by excellent surface diffusion of lithium ion in the interface of α-ZrP/PPy. Particularly, the charge differential density uncovered that LiPSs served as an accurate regulable-switch tune the electronic transfer in the redox reactions relating to α-ZrP and PPy. Thus, the α-ZrP/PPy based cathode owned outstanding adsorption capacity as well as electric catalytic properties in the Li-S batteries.