Exploration of metal-layered double hydroxide composite material for hybrid capacitor produced by facile and efficient electrodeposition process

Manganese cobaltite (MCO) with an empirical formula Mn 2-x Co 1+x O 4 and cobalt-nickel layered double hydroxide (CN-LDH) composite were synthesized through a dual-step electrodeposition approach. This process commenced with cyclic voltammetry (CV) electrodeposition of manganese cobaltite (MCO) on nickel foam (NF) followed by annealing in air. The next step was the CV electrodeposition of CN-LDH on MCO. The enhanced composite material MCO-2.5@CN-LDH yielded a remarkable specific capacity of 415.9 mAh g -1 at a specific current of 1 A g -1 in a three-electrode configuration using 2 M KOH electrolyte. The electrodeposition method is credited for producing these competitive results, since the method excludes polymeric binders which would make it necessary to include conductive additives to compensate for the increased resistivity in the electrode materials. This positive electrode and the activated carbon from cooked chicken bone waste (CCBW) as the negative electrode were assembled into hybrid supercapacitor device (MCO-2.5@CN-LDH//CCBW) using the same electrolyte. The device generated a specific energy of 55.8 Wh kg -1 corresponding to a specific power of 940.4 W kg -1 at 1 A g -1 . A device stability measurement at 10,000 galvanostatic charge-discharges (GCD) at 7 A g -1 produced a capacity retention of 81.6% and coulombic efficiency of 99.8%. Owing to these promising results, the fabricated materials proved to be capable to be employed as high specific energy supercapacitor. • A binder-free layered double hydroxide was synthesized by electrodeposition method. • Combination of nanograin, and nanoflakes morphologies were observed. • High specific capacity of 415.9 mAh g -1 was recorded for the half cell. • An outstanding specific energy of 55.8 Wh kg -1 was obtained for the device. • The material revealed good performance for future supercapacitor applications.