Journal of Materials Science & Technology | 2021
Guanine-assisted N-doped ordered mesoporous carbons as efficient capacity decaying suppression materials for lithium-sulfur batteries
Abstract
Abstract Lithium-sulfur (Li–S) batteries are considered promising next-generation energy storage devices due to their high weight capacities and theoretical energy densities, which are significantly higher than those of conventional lithium-ion batteries. However, the sulfur cathode presents two major drawbacks, specifically low specific capacity caused by the poor electrical conductivities of the active materials and fast capacity decay caused by polysulfide dissolution/shuttling. Herein, a high-rate and high-stability dendritic material consisting of N-doped ordered mesoporous carbons (NOMCs) was successfully synthesized via a facile and low-cost calcination method. The highly ordered mesoporous carbon skeleton limited the growth of the sulfur nanofiller within its channels and provided the necessary electrical contact with the insulating sulfur. Furthermore, N-doped heteroatoms presented strong binding sites for trapping polysulfide intermediates, achieving high electrochemical activity, which promoted polysulfide conversion reactions. As a result, the prepared NOMC−2/S cathode material with 1.2–1.5 mg cm−2 of sulfur displayed excellent electrochemical performance with a high-rate capability of 460.5 mAh g−1 at 1 C, a high specific capacity of 530.9 mAh g−1 after 200 cycles at 0.1 C, and a decay rate of ∼0.19% per cycle.