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 NaBH4 reduction methods. The introduction of sulfur vacancies in 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 nanoarchitecture and sulfur vacancies, the optimal Vs-CMS integrated cathode delivers a high areal capacity of 0.56 mAh cm−2 at 1 mA cm−2, good rate performance of 0.34 mAh cm−2 at 30 mA cm−2, and excellent cycling stability with 96.7% capacity retention after 10,000 cycles. Furthermore, capacitive-type porous framework activated carbon (PFAC) anodes are used to couple with the optimal Vs-CMS cathodes for assembling HSCs. The as-obtained PFAC anodes possess a high specific capacitance of 112.1 F g− 1 at 0.25 A g− 1, high rate capability of 46.3 F g− 1 at 10 A g− 1, and good cycling stability of 95.5% capacitance retention after 10,000 cycles. The as-assembled HSCs deliver 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 10,000 cycles.