Improved Performance and Immobilizing Mechanism of N-doping Carbon Aerogel with Net Channel via Long-Chain Directing for Lithium-Sulfur Battery

摘要

A novel net channel and N-doping carbon aerogel (CA) are successfully prepared by an in situ and facile method via polyimide (PI) inducting for lithium-sulfur (Li-S) batteries. The PI-directing carbon aerogel (PI-CA) presents a cross-linked framework, abundant porosity, and a high specific surface area. PI-CA spheres present effective immobilizing polysulfides and high loading sulfur for a Brunauer-Emmett-Teller (BET) surface area of 2039.4 m(2) g(-1) and N-doping via physical and chemical adsorption. The Li-S batteries with PI-CA as cathode matrix exhibit excellent performance. In particular, the initial specific capacity of 2PI-CA/S with sulfur content of 73.8 wt% delivers 1338 mAh g(-1) and remains at 1102 mAh g(-1) after 100 cycles at 0.2 C. The enhanced electrochemical performance mainly benefits from the mesh structure of the composite and the interaction between nitrogen and lithium polysulfide. The theoretical calculation by density functional theory (DFT) further supports the template effect of PI and the anchoring mechanism of polysulfides.