Transitional metal oxide anodes have attracted wide attention toward lithium-ion batteries (LiBs) and supercapacitors (SCs) owing to their high theoretical capacity. However, poor conductivity and huge volume change limit their commercialization. Herein, nitrogen (N)-doped reduced graphene oxide (rGO) incorporated Ni2O3-Co3O4@MoS2 hollow composite nanocubes (Ni-Co-Mo@G-N HCNCs) are studied as an anode for LiBs and as a cathode for SCs. The resulting Ni-Co-Mo@G-N HCNCs reveal the cube-like morphology with a hollow structure. The N-doped rGO network can effectively provide a good conductive pathway and also preserve excellent integrity between the active particles. When investigated as the LIB anode, the Ni-Co-Mo@G-N HCNCs exhibit excellent reversibility and good rate capability. Notably, a superior reversible capacity of 1119 mA h g−1 is obtained over 300 cycles (at 0.1 A g−1). This electrode also demonstrates outstanding reversibility and excellent rate capability when operating at 1 and 2 A g−1 over 1000 cycles. Additionally, the Ni-Co-Mo@G-N HCNCs are investigated as a battery-type electrode for SCs, delivering excellent capacity retention of 91.7 %. Owing to the synergic effect of compositional structure, interior hollow structure, and N-doped rGO network for good reversibility and rate capability, the Ni-Co-Mo@G-N HCNCs are very promising for high-performance energy storage device applications.

Metal carbonate hydroxides/sulfides have attracted great interest from researchers in the energy storage-related fields due to their versatile electrochemical characteristics. Moreover, the synthesis of such a combination of materials is a challenging task. Herein, nickel-copper carbonate hydroxides with nanowire morphology (i.e., NiCu NWs) was in situ prepared over the carbon textile by a facile hydrothermal method. The synthesized NiCu-2 with equimolar salt concentrations (Ni-25 mM; Cu-25 mM) delivered a superior areal capacity of 65.5 µAh cm−2 at 1.5 mA cm−2 than the other two NiCu electrodes. To further improve the redox chemistry and electrochemical performance, cobalt sulfide (CS) nanolayer was electrodeposited on the NiCu NWs to make CS@NiCu-2 composite. The composite material with the combined redox features of both CS and NiCu materials as well as the hybrid morphology exhibited an improved areal capacity of 275.6 µAh cm−2 at the same current density. Furthermore, the hybrid supercapacitor (HSC) was fabricated using the CS@NiCu-2 as a positive electrode and the activated carbon as a negative electrode. For the fabricated device, a good areal capacitance of 410 mF cm−2 was achieved along with the maximum energy and power densities of 131.2 µWh cm−2 and 15000 µW cm−2, respectively. Besides, the practical applicability of HSC was tested by powering electronic gadgets.

Biomass-derived electrodes inherently containing redox-active species have gained extensive attention recently due to their availability, eco-friendliness, sustainability, and low cost. We report novel binder-free faradic surface redox onion-derived carbon positive electrode with nano regime particles by hydrothermal synthesis and Na+ and Cl− ions diffused porous carbon negative electrode via a carbonization method. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of oxidized sulfur and (N-6) pyridinic N-based redox groups inherently present in the as-prepared compounds. The electrochemical analysis of the positive electrode revealed its faradic redox type of energy storage mechanism with an excellent specific capacitance of 1805 F g−1 at the current density of 3 A g−1 as well as appreciable long-term cycling stability (76.8% retention after 10000 charge-discharge cycles). Meanwhile, the negative electrode exhibited a maximum specific capacitance of 373 F g−1 at 1 A g−1 with outstanding long-term cycling stability (100.7% retention after 10000 cycles). The fabricated polyvinyl alcohol-potassium hydroxide gel electrolyte-based quasi-solid-state hybrid supercapacitor (QHSC) delivered excellent energy density and power density of 19.94 Wh kg−1 and 374.99 W kg−1, respectively with an ultralong cyclic life (102.3% retention) over 10000 cycles. Furthermore, the QHSC was connected to a solar panel to store renewable energy. Solar charged QHSC effectively powered a speedometer, enlightening its potential application in advanced sustainable energy storage systems.