Duan Research Group

Hetero-integrated Nanostructures and Nanodevices


A fundamental look at electrocatalytic sulfur reduction reaction

Lele Peng, Ziyang Wei, Chengzhang Wan, Jing Li, Zhuo Chen, Dan Zhu, Daniel Baumann, Haotian Liu, Christopher S. Allen, Xiang Xu, Angus I. Kirkland, Imran Shakir, Zeyad Almutairi, Sarah Tolbert, Bruce Dunn, Yu Huang, Philippe Sautet & Xiangfeng Duan

Nat. Catal. 3, 762-770 (2020)

The fundamental kinetics of the electrocatalytic sulfur reduction reaction (SRR), a complex 16-electron conversion process in lithium–sulfur batteries, is so far insufficiently explored. Here, by directly profiling the activation energies in the multistep SRR, we reveal that the initial reduction of sulfur to the soluble polysulfides is relatively easy owing to the low activation energy, whereas the subsequent conversion of the polysulfides into the insoluble Li2S2/Li2S has a much higher activation energy, contributing to the accumulation of polysulfides and exacerbating the polysulfide shuttling effect. We use heteroatom-doped graphene as a model system to explore electrocatalytic SRR. We show that nitrogen and sulfur dual-doped graphene considerably reduces the activation energy to improve SRR kinetics. Density functional calculations confirm that the doping tunes the p-band centre of the active carbons for an optimal adsorption strength of intermediates and electroactivity. This study establishes electrocatalysis as a promising pathway to tackle the fundamental challenges facing lithium–sulfur batteries.
UCLA, Department of Chemistry and Biochemistry
607 Charles E. Young Drive East, Box 951569
Los Angeles, CA 90095-1569
E-mail: xduan@chem.ucla.edu