Electroactivated Modulation of Highly Aligned Manganese-Doped Cobalt Sulfide Nanoplate Arrays for High-Performance Hybrid Supercapacitors

Transition-metal sulfides have been identified as one of the promising cathode materials of battery type for hybrid supercapacitors (HSCs). However, there are still huge obstacles to their practical applications due to the major problems of poor structural stability and limited redox active sites. In this work, a high-performance cathode material based on three-dimensional porous Mn-doped Co₉S₈ nanoplate arrays (Mn-Co₉S₈ NPAs) on Ni foam has been synthesized via a facile electroactivation-modified metal–organic framework self-templating sulfurization strategy. It has been found that the introduction of Mn²⁺ ions can guarantee the structural integrity of the nanoplate arrays and effectively reduce the electron density near Co sites. By the synergistic modulation of the geometric and electronic structures, the Mn-Co₉S₈ NPAs electrode delivers an ultrahigh capacity of 569.4 mAh g^–1 (4099.7 F g^–1) at 1 A g^–1 with superior cycling stability. An HSC assembled with the electrode materials exhibits a high energy density of 73.1 Wh kg^–1 at a power density of 737.5 W kg^–1 and yields a 98.2% capacitance retention after 5000 cycles, indicating robust cycling stability as well. This work demonstrates a doping engineering strategy to regulate the physicochemical properties of metal sulfides for efficient energy-storage and conversion applications.