Mesoporous carbon/sulfur composite with N-doping and tunable pore size for high-performance Li-S batteries

Abstract

Mesoporous carbons (MCs) were used as the matrixes to load sulfur for lithium sulfur (Li-S) batteries, and pore sizes were tuned by heat treatment at different high temperatures. The cathode material shows the highest discharge capacity of 1158.2 mAh g−1 at the pore size of 4.1 nm among as-prepared nitrogen-free materials with different sizes. Meanwhile, the nitrogen doping of mesoporous carbon helps to inhibit the diffusion of polysulfide species via an enhanced surface adsorption. The carbon/sulfur containing N (4.56%) shows a high initial discharge capacity of 1315.8 mAh g−1 and retains about 939 mAh g−1 after 100 cycles at 0.2 C. The improved electrochemical performance is ascribed to the proper pore size, surface chemical property, and conductivity of the N-doped carbon material.