Zinc ferrite nanoparticles as electrode material for supercapacitors.

In the realm of sustainable and renewable nanotechnology, supercapacitors have appeared as the dominant solution for energy conversion and storage. Ferrites have been widely explored in magnetic, electronic and microwave devices, and are now being explored for applications in energy storage devices due to the possibility of achieving fast and reversible surface Faradic reactions. From this perspective, a simple and inexpensive chemical co-precipitation method was used to synthesize ultrasmall ZnFe₂O₄nanoparticles (NPs). As an electrode material the ZnFe₂O₄NPs show a gravimetric capacitance of 186.6 F g^-1at a current density of 1 A g^-1in 1 M H₂SO₄. Furthermore, the ZnFe₂O₄NP-based electrode shows exceptional capacitive retention of 98% over 1000 cycles at a current density of 3 A g^-1. An asymmetric ZnFe₂O₄NP//NiO NP device was fabricated, which achieved a power density of 302.3 W kg^-1at a current density of 1.5 A g^-1and an energy density of 14.85 W h kg^-1. After 1500 cycles, the device demonstrated capacity retention of 99.4% at 1.5 A g^-1in long-term stability testing with 100% efficiency. Our study suggests that ZnFe₂O₄NPs are promising as a material for future energy storage applications.