Bismuth manganese oxide based electrodes for asymmetric coin cell supercapacitor

Binary metal oxides are deposited via simple chemical routes for high-performance energy storage applications. In this work, we developed nanostructures of BiMnO3 on Ni foam using a hydrothermal method. Initially, the (0 1 0) and (1 1 0) planes confirmed the presence of the BiMnO3 phase. Snow fungus-like nanostructure was transferred to porous interconnected nanoflakes with an increase in deposition time. These nanoflakes serve as large active sites that are beneficial for the diffusion of electrolytic ions that enhance the charge storage and transport process. Consequently, the two-dimensional interconnected nanoflakes showed a high diffusion coefficient, standard rate constant, and minimum transfer coefficient. In addition, BiMnO3 exhibited an aerial capacitance of 6000 mF cm−2 (1500 Fg−1) with an energy density of 102 Wh kg−1 at an applied current density of 20 mA cm−2. For practical applications, an asymmetric coin cell (ACC) device was assembled using BiMnO3 as the positive electrode and activated carbon as the negative electrode in 3 M aqueous KOH as an electrolyte. The fabricated ACC device had an energy density of 14.4 Wh kg−1 at a power density of 50 W kg−1 with a 1.2 V potential; the capacitive retention was 90 %, with 97 % Coulombic efficiency up to 5000 cycles. Accordingly, the results determined that BiMnO3 can be used as an electrode material for high-performance energy storage applications.