Facile synthesis of CoFe2O4 powders for aqueous charge storage

In this work, the electrochemical performance of CoFe₂O₄ powders was improved by selecting a proper organic fuel (glycine, urea, and citric acid) for the solution combustion synthesis method. Burning the glycine fuel led to the higher crystallinity, larger particle size, and spongy microstructure of the CoFe₂O₄ powders, caused by its high combustion temperature and combustion rate. In contrast, using urea and citric acid fuels resulted in higher specific surface areas of 57 and 47 m² g⁻¹, respectively, than that (23 m² g⁻¹) obtained using the glycine fuel due to the lower combustion temperature. The glycine-assisted CoFe₂O₄ powders exhibited high electrochemical performance, including high specific capacitances of 718 and 446 F g⁻¹ at current densities of 1 and 20 A g⁻¹, respectively. Furthermore, the asymmetric aqueous capacitor of CoFe₂O₄//activated carbon electrochemically stored an energy density of 42 Wh kg⁻¹ for the potential window of 0–1.5 V.