2D Sandwich-Like α-Zirconium Phosphate/Polypyrrole: Moderate Catalytic Activity and True Sulfur Confinement for High-Performance Lithium-Sulfur Batteries.

Although lithium-sulfur batteries are promising environmentally friendly and low-cost energy storage devices with high energy densities, many obstacles such as poor conductivity, volume expansion and the "shuttle effect" still limit their large-scale commercialization. In this work, a 2D sandwich-like α-ZrP/polypyrrole (α-ZrP/PPy) material with a nanosheet structure was designed as a sulfur host. The material can provide unique ion transfer channels for the rapid transfer of Li+ ions and catalytically promote the conversion of lithium polysulfides (LiPSs). Moreover, the α-ZrP nanosheets provides a true covalent anchor for sulfur species, whereas the PPy builds a physical barrier and forms a conductive network for accelerating the electron transport and promoting the electrochemical performance. In addition, the moderate catalytic activity and true sulfur confinement effect of α-ZrP were confirmed by experiments and theoretical calculations. The α-ZrP/PPy@S cathode exhibits a highly reversible capacity of 727.2 mAh g-1 even at a high current density of 5 C, offering a novel cathode material for high performance Li-S batteries.