Enhanced supercapacitive performance in Ni3S2/MnS composites via an ion-exchange process for supercapacitor applications

Enhanced performance of hybrid supercapacitors by the synergistic effect of Co(OH)2 nanosheets and NiMn layered hydroxides

A self-supporting composite electrode material with a unique three-dimensional structure was synthesized by in-situ growth of nanoscale NiMnLDH-Co(OH)₂ on a nickel foam substrate via hydrothermal electrodeposition. The 3D layer of NiMnLDH-Co(OH)₂ provided abundant reactive sites for electrochemical reactions, ensuring a solid and conductive skeleton for charge transfer and resulting in significant enhancement of electrochemical performance. The composite material showed a strong synergistic effect between the small nano-sheet Co(OH)₂ and NiMnLDH, which promoted reaction kinetics, while the nickel foam substrate acted as a structural conductivity agent, stabilizer, and good conductive medium. The composite electrode showed impressive electrochemical performance, achieving a specific capacitance of 1870F g^-1 at 1 A g^-1 and retaining 87% capacitance after 3000 charge-discharge cycles, even at a high current density of 10 A g^-1. Moreover, the resulting NiMnLDH-Co(OH)₂//AC asymmetric supercapacitor (ASC) demonstrated remarkable specific energy of 58.2 Wh kg^-1 at a specific power of 1200 W kg^-1, along with outstanding cycle stability (89% capacitance retention after 5000 cycles at 10 A g^-1). More importantly, DFT calculations reveal that NiMnLDH-Co(OH)₂ facilitates charge transfer, accelerating surface redox reactions and increasing specific capacitance. This study presents a promising approach towards designing and developing advanced electrode materials for high-performance supercapacitors.

Nanosilver-Particles Integrated Ni3 Sn2 S2 -CoS Composite as an Advanced Electrode for High Energy Density Hybrid Cell

An ion-exchange process is a promising approach to design advanced electrode materials for high-performance energy storage devices. Herein, a nanostructured Ni₃ Sn₂ S₂ -CoS (NSS-CS) composite is fabricated by successive hydrothermal and ion-exchange processes. Since the incorporation of redox-rich cobalt element enables the NSS-CS composite to be more electrochemically active, its impact on the electrochemical performance is therefore extensively studied. Particularly, the NSS-CS-0.2 g electrode material delivered a high areal capacity of 830.4 µAh cm^-2 at 5 mA cm^-2 . Additionally, a room-temperature wet-chemical approach is employed to anchor nanosilver (nAg)-particles on the NSS-CS-0.2 g (nAg@NSS-CS-0.2 g) to further exalt its electrokinetics. Consequently, the nAg@NSS-CS-0.2 g electrode shows a higher areal capacity of 948.5 µAh cm^-2 (193.5 mAh g^-1 ) than that of the NSS-CS-0.2 g. Furthermore, its practicability is also examined by assembling a hybrid cell. The assembled hybrid cell delivers a high areal capacity of 969.2 µAh cm^-2 (49.2 mAh g^-1 ) at 7 mA cm^-2 and maximum areal energies and power densities of 0.784 mWh cm^-2 (40.8 Wh kg^-1 ) and 45 mW cm^-2 (2347.4 W kg^-1 ), respectively. The efficiency of the hybrid cells is also tested by harvesting solar energy, followed by energizing electronic components. This work can pave the way for significant attraction in designing advanced electrodes for energy-related fields.