Ultra-fine zinc oxide nanocrystals decorated three-dimensional macroporous polypyrrole inverse opal as efficient sulfur hosts for lithium/sulfur batteries

Abstract

Despite high theoretical capacity (1675 mAh g−1) and low cost of the lithium/sulfur (Li/S) batteries, their industrial road is impeded by rapid capacity loss and poor rate performances caused by the dissolution of lithium intermediate in the electrolyte. In this work, a composite is reported, which consists of highly dispersed ultrafine (~5 nm) zinc oxide (ZnO) nanocrystals decorated on conductive three-dimensionally macroporous polypyrrole (3DOMPPy) inverse opal, for polysulfides immobilization in Li/S batteries. Compared with carbon matrixes, 3DOMPPy provides a stronger lithium polysulfides binding site, due to its unique macroporous structure. Through constructing 3D ordered macroporous structure of PPy, a fast electron transfer pathway and an efficient buffer space for sulfur are provided. Furthermore, polar ZnO can confine polysulfides greatly by chemical adsorption, which is verified by density functional theory calculations. Consequently, S-3DOMPPy@ZnO demonstrates durable long-term cyclability (794.5 mAh g−1 after 300 cycles at 0.1 C) as well as a remarkable rate capability (515.6 mAh g−1 at 2 C).