Molecular Connectors Boosting the Performance of MoS 2 Cathodes in Zinc‐Ion Batteries
Résumé
Zinc-ion batteries (ZIBs) are promising energy storage systems due to high energy density, low-cost, and abundant availability of zinc as a raw material. However, the greatest challenge in ZIBs research is lack of suitable cathode materials that can reversibly intercalate Zn2+ ions. 2D layered materials, especially MoS2-based, attract tremendous interest due to large surface area and ability to intercalate/deintercalate ions. Unfortunately, pristine MoS2 obtained by traditional protocols such as chemical exfoliation or hydrothermal/solvothermal methods exhibits limited electronic conductivity and poor chemical stability upon charge/discharge cycling. Here, a novel molecular strategy to boost the electrochemical performance of MoS2 cathode materials for aqueous ZIBs is reported. The use of dithiolated conjugated molecular pillars, that is, 4,4′-biphenyldithiols, enables to heal defects and crosslink the MoS2 nanosheets, yielding covalently bridged networks (MoS2-SH2) with improved ionic and electronic conductivity and electrochemical performance. In particular, MoS2-SH2 electrodes display high specific capacity of 271.3 mAh g−1 at 0.1 A g−1, high energy density of 279 Wh kg−1, and high power density of 12.3 kW kg−1. With its outstanding rate capability (capacity of 148.1 mAh g−1 at 10 A g−1) and stability (capacity of 179 mAh g−1 after 1000 cycles), MoS2-SH2 electrodes outperform other MoS2-based electrodes in ZIBs.
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