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Porous Molybdenum Carbide Nanorods as Novel “Bifunctional” Cathode Material for Li‐S Batteries
Author(s) -
Wang Zhao,
Liu Jia,
Sun Liqun,
Zhang Yuhang,
Fu Qiang,
Xie Haiming,
Sun Hao
Publication year - 2018
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.201801505
Subject(s) - bifunctional , overpotential , cathode , polysulfide , materials science , chemical engineering , nanorod , adsorption , electrochemistry , molybdenum , nanotechnology , chemistry , catalysis , inorganic chemistry , electrode , electrolyte , metallurgy , organic chemistry , engineering
The shuttle effect of polysulfide is the primary obstacle in Li‐S batteries. Although some effort has been made to suppress the shuttle process, more highly conductive materials with stronger adsorption ability to polysulfides are still in urgent demand. Another important problem is the deteriorating performance of Li‐S batteries with prolonged cycling owing to irreversible deposition of lithium sulfide (Li 2 S). However, a host material for the effective conversion of insoluble Li 2 S has been elusive up to now. Herein, porous molybdenum carbide nanorods (Mo 2 C NRs), with high catalytic activity for Li 2 S and ultrastrong adsorption for polysulfides, are used as a “bifunctional” host material and incorporated into sulfur cathodes for the first time. The “bifunctional” Mo 2 C NRs have the advantage of immobilizing polysulfides over the conventional host, with adsorption energies from −4.89 to −8.20 eV for Li 2 S x ( x =1, 2, 4, 6, and 8). The electrochemical analysis shows that Mo 2 C NRs, more than an anchor, can activate Li 2 S by greatly reducing the charging overpotential. Therefore, the irreversible deposition of polysulfides is effectively restrained and the utilization of Li 2 S is clearly enhanced. The Mo 2 C NRs–sulfur composites (Mo 2 C NRs‐S) cathodes provide a capacity of 1298 mA h g −1 at 0.1 C in the Li‐S batteries. More importantly, the battery with Mo 2 C NRs‐S cathodes exhibits a much lower capacity decay of 0.062 % per cycle at 1 C over 500 cycles.