An efficient electrodeposition approach for preparing CoMn-hydroxide on nickel foam as high-performance electrodes in aqueous hybrid supercapacitors

Transition-metal hydroxides (TMHOs) show promise as pseudocapacitive materials for high-energy-density supercapacitors (SCs). However, their intrinsic conductivity is low, and significant volume expansion poses challenges, negatively impacting their electrochemical properties. In the presented study, we have innovatively engineered a CoMn-Layered Double Hydroxide (CM-LDH) composite electrode for SCs. The CM-LDH electrode showcased impressive electrochemical properties, with an exceptional specific capacitance of 10955.5 mF cm[sup]-2[/sup] at 1.0 mA cm[sup]-2[/sup] and maintained 1231.2 mF cm[sup]-2[/sup] at 150.0 mA cm[sup]-2[/sup]. It exhibits robust cycling stability, retaining 83.5 % of its capacitance after 7000 cycles at 35 mA cm[sup]-2[/sup]. These values surpass the performance of most CMLDH-based materials reported in prior studies. The hybrid CM-LDH//AC device revealed a remarkable energy density of 0.409 mWh cm[sup]-2[/sup] at 0.798 mW cm[sup]-2[/sup], thanks to the broad potential window of 1.6 V. Additionally, the electrode demonstrated excellent longevity, maintaining 85.2 % of its actual value after 20,000 charge-discharge cycles at 25 mA cm[sup]-2[/sup], while achieving nearly perfect Coulombic efficiency of about 100 %. This research underscores the potential of CM-LDH nanostructured electrodes as a promising candidate for advanced energy storage technologies.