Effect of calcination time on modulating the properties of battery type NiMn2O4 intended for supercapacitor applications

In this study, the synthesis of nanostructured NiMn2O4 is achieved through the novel wet-chemical reduction synthesis method, maintained at a constant temperature of 500 °C. Variations in calcination time to 4, 5, and 6 h, with a constant synthesis temperature, result in the formation of NiMn2O4 (NMO) nanostructures (NSs). These NMO-NSs are employed as electroactive materials in the assembly of electrochemical supercapacitors. Electrodes, composed of NMO-NSs calcined for 4 h, at constant temperature of 500 °C, are observed to exhibit a high specific capacitance/capacity of 966.7 F g−1 (579 C g−1) respectively, at a scan rate of 5 mV s−1. Retention of 96 % of the specific capacitance is noted after 5000 cycles of the as optimum electrode (NM-4 h). The significant influence of calcination time on the efficiency of electrochemical supercapacitors is highlighted in this research. An asymmetric supercapacitor device (ASSCs), featuring a wide working potential window of 0–1.6 V and a energy density of 38.9 W h kg−1 at a power density of 5 kW kg−1. As fabricated ASSCs demonstrates high specific capacitance of 109.4 F g−1/175 C g−1 with capacitance retention of 79.9 % over 5000 cycles. The potential of highly porous binary NiMn2O4 NSs as suitable materials for high-performance supercapacitor devices is suggested by the findings. [Display omitted] •NMO-NSs are synthesized by novel wet-chemical reduction synthesis method.•NM-4 h electrode showed specific capacitance/capacity of 966.7 F g−1 (579 C g−1) in 1 M KOH.•NM-4 h electrode exhibited 96 % retention after 5000 cycles in 1 M KOH.•NM-4 h//AC ASSCs delivered energy density of 38.9 W h kg−1 with power density 5 W k g−1.