Pulse Electrodeposition of Polyaniline/Mn-Fe Binary Metal Hydroxide Composite Cathode Material for a Zn-Ion Hybrid Supercapacitor

Rechargeable aqueous zinc-ion hybrid supercapacitors and zinc-ion batteries are promising as safe energy storage systems because they combine the advantages of the high energy density of batteries and high power density of supercapacitor. This paper presents the elaboration of polyaniline (PANi)/Mn-Fe binary metal hydroxide (MnFe-BMH) composite cathode material and Zn anode for a Zn-ion hybrid supercapacitor (ZHSC) by electrochemistry. Two electrochemical techniques (voltage pulse and stepwise voltage) are carried out to perform different morphologies and structures of material modifying the cathode and anode electrodes. The ZHSC is packaged with a gel electrolyte solution of ZnSO₄ 1M and MnSO₄ 0.1M. Electrochemical performance of electrode materials and full-cell capacitors are studied by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements. The composite material for electrode modification has an outstanding specific capacitance of 470.3 F/g (167 Wh/kg) at a scan rate of 5 mV/s. Furthermore, this as-prepared electrode also shows excellent cycling stability with 94.6% capacity retention after 11,602 cycles. This demonstrates an improvement in endurance and energy density compared to the industrial SC electrodes.