Electrodeposition of Hierarchical Nanosheet Arrays of NiCo2S4 onto a Polymer Substrate: A New High Power Flexible Battery Electrode

A simple and facile fabrication of hierarchical nanosheet arrays of a ternary system comprising of NiCo2S4 deposited onto conductive copper coated flexible polymer (overhead projector; OHP) electrodes by using electrodeposition (ED) is reported. Such electrochemically modified flexible electrodes show typical faradaic redox reactions consistent with battery-type materials and exhibit higher capacity along with excellent rate performance. Structural morphology and composition of these flexible electrodes are analyzed using spectroscopic and microscopic characterization techniques. Interfacial electrochemical characteristics are investigated by using cyclic voltammetry and electrochemical impedance spectroscopic studies. Effects of several parameters associated with ED process including the concentration, applied cathodic voltage and time duration on the structural morphology of resultant NiCo2S4 deposits and on their charge transfer properties are also analyzed. From these studies it has been found that the optimized electrode, namely Ni-Co-S-1/Cu/OHP shows well defined hierarchical nanosheet arrays of NiCo2S4 grown onto Cu deposited flexible OHP strip electrodes. This particular electrode possesses higher surface roughness, porosity and shows superior electrochemical characteristics as a positive electrode for flexible battery applications. A very high specific capacity of 218.1 mAh g(-1) at a current density of 2 A g(-1) and capacity retention of 86.7% at 10 A g(-1) after 2000 cycles are determined. All these experimental results illustrate the hierarchical nanosheet arrays deposited onto flexible copper coated OHP strip alters the interfacial capacity and could be used as a promising positive electrode for low-cost flexible energy storage devices. (c) 2017 The Electrochemical Society. All rights reserved.