Scalable synthesis of binder-free hierarchical MnCo2O4 nanospikes/Ni(OH)2 nanosheets composite electrodes for high-capacity supercapatteries

Abstract

Supercapatteries have received great attention in recent years due to its excellent charging storage capabilities. The effective electrochemically active surface area of the electrode is crucial in obtaining high capacity in supercapatteries. Herein, we present a scalable synthesis of binder-free hierarchical MnCo2O4 (MCO) nanospikes/Ni(OH)2 (NiOH) nanosheets (MCO/NiOH) nanocomposites for supercapattery electrode application. The MCO/NiOH nanocomposites are synthesized by the two-step hydrothermal method at low-cost without affecting nanostructures and further used as electrodes in fabricating a supercapattery. The synergistic effect of the NiOH nanosheets and MCO nanospikes helps to enhance the electrochemical charge storage performance when compared to their counterparts. The growth of NiOH nanosheets over the MCO nanospikes helps to suppress the self-discharge nature of MCO nanospikes otherwise. The MCO/NiOH//activated carbon supercapattery fabricated in the asymmetric configuration delivers a maximum specific capacity of 890C/g with a high energy density of 75.2 Wh/kg. The MCO/NiOH//activated carbon supercapattery exhibits a capacity retention of 86 % after completing 5000 charge/discharge cycles. Therefore, MCO/NiOH nanocomposite electrodes are capable candidates for the next-generation electrochemical energy storage systems.