Phosphorus and Nitrogen Codoped Porous Carbon-Based Sulfur Host for High-Loading Lithium/Sulfur Batteries

Abstract

Lithium/sulfur (Li/S) batteries are potential candidates for next-generation batteries owing to their high theoretical energy densities and low fabrication costs. High energy density in a practical Li/S cell can be realized using a high-loading sulfur cathode with a lean electrolyte. For commercialization, a high-loading sulfur electrode must have a stable cycling performance at a high rate. In this study, phosphorus and nitrogen codoped porous carbon was prepared and utilized as a sulfur host for a high loading sulfur electrode. The Li/S batteries exhibited stable cycling performance at 1 C. The Li/S batteries delivered a capacity of 553 mAh g-1 after 200 cycles at a 1 C rate with a sulfur cathode loading of 4 mg cm-2 and an electrolyte-to-sulfur ratio of 7 mL g-1, with a capacity degradation rate of only 0.068% per cycle. At a higher sulfur loading of 7 mg cm-2, the batteries exhibited an initial capacity of 1207 mAh g-1, which decreased to 736 mAh g-1 after 100 cycles at 0.1 C. This phosphorus and nitrogen codoped porous carbon appears as a promising sulfur host for high-loading sulfur electrodes in Li-S batteries, enabling stable cycling performance at a high rate under lean electrolyte conditions.