Hierarchical 1D cobalt molybdate@2D cobalt hydroxide core@shell architecture based cathode for high energy hybrid supercapacitors

Capitalizing on the advantages of integrated 1D/2D nanostructures for advanced supercapacitor cathodes, present work presents a hierarchically designed cobalt molybdate@cobalt hydroxide (CM@CH) cathode fabricated through a scalable, binder-free, chemical bath deposition (CBD) method directly on stainless-steel. Through variation of hydrolyzing agent (urea), the growth kinetics were tuned to obtain a distinctive 1D microrods@2D nanoflakes architecture. The optimized CM@CH-3 electrode exhibited high specific surface area with abundant electroactive sites. Owing to the synergistic redox activity of cobalt molybdate and cobalt hydroxide and robust hierarchical structure, the electrode delivered a high specific capacity of 650C g −1 (1302 F g −1 ) at 0.7 A g −1 . The assembled aqueous asymmetric supercapacitor (CM@CH//rGO) achieved 138 F g −1 , 49.2 Wh kg −1 , 0.8 kW kg −1 , and 93% capacitance retention after 10,000 cycles. Likewise, the solid-state device (CM@CH/PVA-KOH/rGO) delivered 98 F g −1 , 35 Wh kg −1 , 0.8 kW kg −1 , and 81% retention after 10,000 cycles, confirming CM@CH as a promising binder-free cathode for next-generation hybrid supercapacitors. The findings confirm that the facile CBD strategy enables binder-free, tunable CM@CH core@shell thin films with a unique 1D microrod@2D nanoflake architecture, enhancing electroactive surface area, faradaic kinetics, and structural durability for next-generation hybrid supercapacitors.