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Atomic‐Scale Dispersed Fe‐Based Catalysts Confined on Nitrogen‐Doped Graphene for Li‐S Batteries: Polysulfides with Enhanced Conversion Efficiency
Author(s) -
Cao Guiqiang,
Wang Zhikang,
Bi Da,
Zheng Jing,
Lai Qingxue,
Liang Yanyu
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202001282
Subject(s) - graphene , separator (oil production) , catalysis , electrochemistry , chemical engineering , lithium (medication) , materials science , adsorption , doping , cyclic voltammetry , inorganic chemistry , chemistry , energy storage , electrode , nanotechnology , organic chemistry , optoelectronics , medicine , physics , endocrinology , engineering , thermodynamics , power (physics) , quantum mechanics
Lithium‐sulfur batteries have been considered as potential electrochemical energy‐storage devices owing to their satisfactory theoretical energy density. Nonetheless, the inferior conversion efficiency of polysulfides in essence leads to fast capacity decay during the discharge/charge cycle. In this work, it is successfully demonstrated that the conversion efficiency of lithium polysulfides is remarkably enhanced by employing a well‐distributed atomic‐scale Fe‐based catalyst immobilized on nitrogen‐doped graphene (Fe@NG) as a coating of separator in lithium‐sulfur batteries. The quantitative electrocatalytic efficiency of the conversion of lithium polysulfides is determined through cyclic voltammetry. It is also proven that the Fe‐N X configuration with highly catalytic activity is quite beneficial for the conversion of lithium polysulfides. In addition, the adsorption and permeation experiments distinctly indicate that the strong anchoring effect, originated from the charge redistribution of N doping into the graphene matrix, inhibits the movement of lithium polysulfides. Thanks to these advantages, if the as‐prepared Fe@NG catalyst is combined with polypropylene and applied as a separator (Fe@NG/PP) in Li‐S batteries, a high initial capacity (1616 mA h g −1 at 0.1 C), excellent capacity retention (93 % at 0.2 C, 70 % at 2 C), and superb rate performance (820 mA h g −1 at 2 C) are achieved.