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Dual-Regulation Strategy to Improve Anchoring and Conversion of Polysulfides in Lithium–Sulfur Batteries

2020; American Chemical Society; Volume: 14; Issue: 6 Linguagem: Inglês

10.1021/acsnano.0c03403

1936-086X

Suya Zhou, Shuo Yang, Xinwei Ding, Yuchong Lai, Huagui Nie, Yonggui Zhang, Dan Chan, Huan Duan, Shaoming Huang, Zhi Yang,

Advanced battery technologies research

The sluggish reaction kinetics at the cathode/electrolyte interface of lithium-sulfur (Li-S) batteries limits their commercialization. Herein, we show that a dual-regulation system of iron phthalocyanine (FePc) and octafluoronaphthalene (OFN) decorated on graphene (Gh), denoted as Gh/FePc+OFN, accelerates the interfacial reaction kinetics of lithium polysulfides (LiPSs). Multiple in situ spectroscopy techniques and ex situ X-ray photoelectron spectroscopy combined with density functional theory calculations demonstrate that FePc acts as an efficient anchor and scissor for the LiPSs through Fe···S coordination, mainly facilitating their liquid-liquid transformation, whereas OFN enables Li-bond interaction with the LiPSs, accelerating the kinetics of the liquid-solid nucleation and growth of Li2S. This dual-regulation system promotes the smooth conversion reaction of sulfur, thereby improving the battery performance. A Gh/FePc+OFN-based Li-S cathode delivered an ultrahigh initial capacity of 1604 mAh g-1 at 0.2 C, with an ultralow capacity decay rate of 0.055% per cycle at 1 C over 1000 cycles.