Atomic V- and Co-Modified Ketjen Black-Sulfur Composite for High-Performance Lithium-Sulfur Batteries

Abstract

In the present study, we encapsulated sulfur with atomic vanadium (V)- and cobalt (Co)-modified Ketjen black (VCKBS) to hinder the shuttle mechanism and enhance the redox kinetics in Li-S batteries. The synthesized composite provided plenty of interfacial active sites and assured smooth electron transfer, which assisted in attaining the balance of the enhanced catalytic activity due to Co and the adsorption ability mainly derived from V. Consequently, the Li-S cells having an optimized composition presented alleviated shuttle effect, enhanced sulfur utilization and conversion efficiency, and showed stable cycling performance and an outstanding rate performance with an initial capacity of 1329 mAh g-1, which was maintained as 1249 mAh g-1 after 100 cycles. Due to impressive experimental specific capacities, the system-level specific energies and energy densities were also predicted using the 1st and 100th discharge capacities. Compared to regular Ketjen black-based cathodes, VCKBS cathodes showed 1342 and 568% improvement in the system-level energy density and specific energy based on the 100th discharge capacities, respectively. This indicates that VCKBS cathodes synthesized in a facile manner are advantageous for higher sulfur loadings at electrolyte-depleted cells and represent a viable endeavor to develop highly stable Li-S batteries.