Mechanochemical growth of a porous ZnFe₂O₄ nano-flake thin film as an electrode for supercapacitor application

Herein, we are reporting a simple, economic, easy to handle, scalable and reproducible mechanochemical i.e. rotational chemical bath deposition (R-CBD) approach for the synthesis of well adhered nano-flake ZnFe₂O₄ thin films (NFs-ZnFe₂O₄) with uniform morphology on a stainless steel (SS) substrate, in comparison with nano-grain ZnFe₂O₄ thin films (NGs-ZnFe₂O₄) prepared using a conventional CBD approach. The influence of rotation on the evolution of the nano-flake morphology in NFs-ZnFe₂O₄ is also investigated. The porous NFs-ZnFe₂O₄ thin films demonstrated excellent pseudocapacitor properties with higher specific capacitance of 768 F g^-1 at high current density of 5 mA cm^-2, stability upto 5000 cycles (88% retention), higher energy density (106 W h kg^-1) and power density (18 kW kg^-1) compared to NGs-ZnFe₂O₄. The results were also found to be higher than those reported earlier for MFe₂O₄ based systems.