Assessment of the electrodeposition synthesized manganese chromite and cobalt-nickel layered double hydroxide composite for high-performance supercapacitor applications

Cyclic voltammetry (CV) electrodeposition synthesis was performed twice to synthesize manganese chromite (MnCr2O4-phi) on NF, where-1.4 < phi < -1.0 is the lower voltage (V vs Ag/AgCl) set in the CV during elec-trodeposition, the higher potential being 0.5 V. This was followed by another electrodeposition of cobalt nickel layered double hydroxide (CoNi-LDH) on MnCr2O4-phi. The unique layered structure of CoNi-LDH produce electrodes with excellent electrochemical performance. MnCr2O4-1.2 V@CoNi-LDH (phi = -1.2 (V vs Ag/AgCl)) yielded the best electrochemical performance in three-electrode set-up in 2 M KOH with the highest specific capacity of 1529.3 C g-1 at a specific current of 1 A g-1. This electrode was incorporated into the hybrid device with activated carbon (AC) from Amarula Husk as the negative electrode (AMH). The device (MnCr2O4-1.2 V@CoNi-LDH//AMH) produced a superb specific energy of 80.2 Wh kg-1 corresponding to a specific power of 1117.7 W kg-1 at 1 A g-1. The device also showed the capacity retention and Coulombic efficiency of the device were 72.9 and 99.7 %, respectively after 15,000 GCD cycles at 9 A g-1. Due to the phenomenal performance, the produced materials are suitable candidates for high energy supercapacitor applications.