Electrodeposition of Sea Urchin and Cauliflower‐like Nickel‐/Cobalt‐Doped Manganese Dioxide Hierarchical Nanostructures with Improved Energy‐Storage Behavior

Abstract

AbstractTransforming the existing Zn–MnO2 primary battery into a secondary battery with enhanced storage behavior and a low cost is of significant interest. Such technology could underpin future energy‐storage development. To acquire this, doped electrolytic manganese dioxide (EMD) with hierarchical nanoarchitectures have been employed as a cathode in the Zn–MnO2 system. EMD is synthesized from manganese sulfate in a sulfuric acid bath with in situ doping of nickel and cobalt ions individually. Sea‐urchin‐shaped EMD has been obtained with nickel as a dopant, whereas cauliflower‐ and pyramidal‐shaped hierarchical nanostructures are observed with cobalt as a dopant, using a facile galvanostatic method without employing any template or surfactant. The structural studies indicated that all EMD samples (in the absence and presence of dopants) are predominantly composed of gamma‐type manganese dioxide; however, the peak intensity increased with increasing concentration of the dopants. The electrochemical results revealed that the Co‐doped EMD composite played a crucial role in increasing the storage capacity of the Zn–MnO2 battery, whereas the Ni‐doped EMD composite resulted in improved longevity compared the Co‐doped and undoped counterparts. The EMD composites individually doped with Ni and Co resulted in improved storage behaviors of 395 and 670 mA h g−1, respectively, against the undoped sample which is 220 mA h g−1, implying that the presence of Co3O4 and mesoporous nanostructured surfaces enhanced the fast kinetics of electrochemical reactions.