Engineering hierarchical manganese molybdenum sulfide nanosheet integrated cathodes for high-energy density hybrid supercapacitors

Abstract

Assembling hybrid supercapacitors (HSCs) has been demonstrated as a feasible tactic to elevate the overall energy densities of SCs. Meanwhile, the design and construction of integrated electrodes is also a rational consideration for boosting the charge storage capability. Herein, we report a novel integrated cathode based on hierarchical manganese molybdenum sulfide nanosheets (Mn-Mo-S NSs) via a cost-effective and facile two-step hydrothermal synthetic strategy. The open microstructure of the Mn-Mo-S NSs enables fast electron/ion transportation throughout the electrode. Consequently, the Mn-Mo-S NS integrated cathode possesses large areal and specific capacities (0.373 mA h cm⁻² and 392.6 mA h g⁻¹ at 2 mA cm⁻²), excellent rate properties as well as superb cycling stability (96.2% of capacity retention over 10 000 cycles). Furthermore, the HSCs are elaborately fabricated using Mn-Mo-S NS integrated cathodes and iron oxide particles encapsulated in reduced graphene oxide (Fe₂O₃@rGO) anodes, which deliver outstanding electrochemical properties, including a high specific capacity of 91.1 mA h g⁻¹ and a volumetric capacity of 1.99 mA h cm⁻³, a superb energy density of 72.9 W h kg⁻¹, as well as outstanding cycling life with 94.6% capacity retention over 10 000 cycles.