Dual-Regulation Strategy to Improve Anchoring and Conversion of Polysulfides in Lithium-Sulfur Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 32491831.
- Also identified by DOI 10.1021/acsnano.0c03403.
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Abstract
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 <i>in situ</i> spectroscopy techniques and <i>ex situ</i> 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 Li<sub>2</sub>S. 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<sup>-1</sup> at 0.2 C, with an ultralow capacity decay rate of 0.055% per cycle at 1 C over 1000 cycles.