Systematic Study of Effect on Enhancing Specific Capacity and Electrochemical Behaviors of Lithium-Sulfur Batteries

摘要

Herein, a flexible method is designed to engineer nitrogen-doped carbon materials (NC) with different functional and structural specialties involving N-doping level, graphitization, and surface area via tuning the carbonization temperature of the pre-prepared zeolitic imidazolate framework-8 (ZIF-8 ) crystals. With the aim to unveil the effect of these features on the electrochemical performance of sulfur cathode, these samples are evaluated as sulfur host and comprehensively investigated. NC-800 (800 degrees C, 10.45%N, 1032.4 m(2) g(-1)) exhibits the best electrochemical capability comparing with NC-700 (700 degrees C, 16.59%N, 891.4 m(2) g(-1)) and NC-900 (900 degrees C, 7.59%N, 987.6 m(2) g(-1)). High surface area and N-doping can work together to well increase the capacity of sulfur cathode, thanks to the improved transportation of charge carriers and effective anchoring of active sulfur, while the latter specialty just makes sulfur cathode have decent capacity in case of low surface area. Graphitization and quaternary nitrogen favorably improve the electric conductivity of the electrode, empowering the improvement of discharge capacity initially and rendering the good cyclability cooperatively relying on the effective immobilization of active materials. The related results suggest the significance of rational design of carbon maxtrix for sulfur to improve the performance of Li-S batteries.