Engineered Interfusion of Hollow Nitrogen-Doped Carbon Nanospheres for Improving Electrochemical Behavior and Energy Density of Lithium-Sulfur Batteries

Hollow nanostructures are one of promising sulfur host materials for lithium-sulfur (Li-S) batteries, but the ineffective contact among discrete particles usually generates overall poor electrical conductivity and low volumetric energy density. A new interfused hollow nitrogen-doped carbon (HNPC) material, derived from imidazolium-based ionic polymer (ImIP)-encapsulated zeolitic imidazolate framework-8 (ZIF-8), is reported. A novel method for ZIF-8 disassembly induced by the decomposition of the ImIP shell is proposed. The unique structural superiority gives the resultant electrodes remarkable cycling stability, high rate capability, and large volumetric energy density. A stable reversible discharge capacity over 562 mA h g(-1) at 2 C is achieved after prolonged cycling for 800 cycles and the average capacity decay per cycle is as low as 0.035%. The electrochemical performance achieved greatly surpasses that of ZIF-8-derived carbon matrices and conventional nitrogen-doped carbon materials. This proposed methodology opens a new avenue for the design of hollow-structured carbon nanoarchitectures with target functionalities.