Sulfur Vacancies Reinforced Cobalt Molybdenum Sulfide Nanosheets Integrated Cathode for High-Energy Density Hybrid Supercapacitors

Abstract

Rational design and construction of bimetallic sulfide materials integrated cathode with well-defined hierarchical nanoarchitectures plays a vital role in boosting the electrochemical performance of hybrid supercapacitors (HSCs). Herein, sulfur vacancies reinforced cobalt molybdenum sulfide nanosheets (Vs-CMS) integrated cathodes are prepared by hydrothermal and sodium borohydride reduction methods. The introduction of sulfur vacancies in cobalt molybdenum sulfide nanosheets (CMS) not only contributes to more active sites for faradic redox reactions, but also accelerates electron and ion transmission. Benefiting from the synergistic effects of well-defined hierarchical nanoarchitectures and sulfur vacancies, the optimal Vs-CMS integrated cathode delivers a high areal capacity (0.56 mAh cm-2 at 1 mA cm-2), good rate performance (0.34 mAh cm-2 at 30 mA cm-2), and excellent cyclic stability (96.7% capacity retention after 10000 cycles). Furthermore, capacitive-type porous framework activated carbon (PFAC) anodes are prepared to couple with the optimal Vs-CMS cathodes for assembling HSCs. The as-assembled HSC delivers maximum energy density of 73.2 Wh kg-1 and power density of 3014.7 W kg-1, and prominent cyclic stability of 93.3% capacity retention after 10000 cycles.

Keywords: cobalt molybdenum sulfide nanosheets, sulfur vacancy, battery-type electrode, integrated cathode, hybrid Supercapacitor