Engineering Ni Quantum Dot Ledges for Catalytic Cleavage of Vertically Anchored Lithium Polysulfides on Mo_<i>x</i>C Nanosheets as Efficient Sulfur Hosts for Li-S Batteries.

Abstract

Lithium-sulfur batteries show great potential for next-generation energy storage but suffer from the shuttle effect, low conductivity, and sluggish kinetics, resulting in poor cycling and power performance. In this work, Mo atoms were uniformly incorporated into amorphous carbon nanosheets via a metal-coordinated polymerization of dopamine, followed by the uniform anchoring of Ni quantum dots on their surfaces. The oxygen anions coordinated with Mo atoms act as strong binding sites, effectively adsorbing lithium atoms of lithium polysulfide species. As a benefit from the height matching, the sulfur species are able to fully contact the quantum dot ledges and undergo rapid catalytic cleavage. As a result, the optimized sulfur cathode delivers a high initial specific capacity of 1340.2 mAh g^-1 at 0.2 C and 821.7 mAh g^-1 at 1 C and retains 495.8 mAh g^-1 after 500 cycles at 1 C, with a low capacity decay rate of only 0.079% per cycle.