Electronic structure adjustment of lithium sulfide by a single-atom copper catalyst toward high-rate lithium-sulfur batteries

Electrocatalytically reducing the energy barrier for Li2S deposition/dissociation is a promising strategy for high -rate Li-S batteries. However, the catalytic sites would be covered by the insulating Li2S product during discharge, which deteriorates the catalytic activity. Here, suggested by first-principles calculations, single-atom copper (SA -Cu) was screened out to endow the insulator-to-metal transition of adsorbed Li2S in view of the electronic structure. In addition to the thermodynamically reduced redox energy barrier, metallic Li2S nuclei deposited on SA-Cu decorated nitrogen-doped carbon fiber foam (SA-Cu@NCNF) with favorable electronic transport present 3D spherical clusters rather than conventional 2D lateral morphology by continuous 3D nucleation and growth. The Li2S deposition capacity and the catalytic efficiency of Li2S-covered catalytic sites are thus greatly improved. As a result, SA-Cu@NCNF based Li-S cells with a sulfur loading of 4 mg cm- 2 retained an areal capacity of 1.60 mAh cm-2 at 5 C after 500 cycles (0.038% decay per cycle). A competitive areal capacity of 8.44 mAh cm-2 was obtained at 0.2 C with a sulfur loading of 10 mg cm-2. The demonstration of the distinctive design of catalysts to adjust the electronic structure of adsorbed Li2S paves the way for developing high-rate and long-life Li-S batteries.

Automated summary

By adjusting the electronic structure of the catalyst, this study improved the coverage of Li2S products on catalytic sites during discharge. It was found that using single-atom copper as a catalyst can achieve control over the adsorbed Li2S electronic structure and form 3D spherical clusters of Li2S nuclei on SA-Cu decorated carbon fiber foam. This design demonstrates the importance of catalyst design in adjusting the adsorbed Li2S electronic structure for developing high-rate and long-life Li-S batteries.