Three-Dimensional Carbon-Catalyst As Sulfur Host for Polysulfide Regulation in Lithium-Sulfur Batteries

Abstract

The ever-growing industrial society demand for limited natural resources and global energy consumption have given rise to the fast development of renewable energy storage technologies. Rechargeable batteries are considered to be indispensable for storing the supply of clean-but-intermittent energy sources, including solar and wind, in an efficiently and economically viable manner. Specifically, lithium-ion batteries (LIBs) with the reliable power capability and relatively mature storage mechanisms are commercialized in the market. However, due to shortage, high prices of lithium minerals, the physical energy density limits of innately available crystal sites, LIBs are unlikely to satisfy the need for grid-scale energy storage system in the long run. The urgent research for alternative sustainable energy storage device has led to the study of lithium-sulfur batteries (LSBs). With the new chemistries based on multi-electron conversion reaction between sulfur and lithium, LSBs are attracting great attention owing to large theoretical energy density of 2600 W h kg−1, high natural abundance and low cost of the sulfur source. Yet, despite their intriguing virtues, the fulfillment of sulfur electrochemical performance is perplexed by several intractable challenges that cause undesirable capacity fading and cycling life. Triggered by continuous round-trip diffusion in ether-based electrolyte, the shuttling effect of highly active lithium polysulfides (LiPSs) will eventually cause severe sulfur loss, electrode decomposition, and Coulombic inefficiency in LSBs. Targeting this issue, we proposed the synthesis of a novel sulfur host in cathode based on a honeycomb-like, porous nitrogen-doped carbon network consisting of MoC with three-dimensional architecture as sulfur host to suppress the shuttling behavior of LiPSs. Benefiting from the interconnected carbon with strong physical adsorption and MoC planes as catalytic sites for acceleration of redox kinetics. We demonstrated experimentally here that this sulfur reservior could realize the improved cell performance with high electronic conductivity, excellent sulfur chemisorption, high rate capacity with 1316 at 0.1 C, 646mAh g-1 at 3C, and long cycling stability with a small capacity decay rate.