Synthesis, structure and supercapacitive behavior of spinel NiFe2O4 and NiO@NiFe2O4 nanoparticles

Abstract NiFe2O4 and NiO@NiFe2O4 nanocrystalline spinels were synthesized by a hydrothermal method. The structural, electronic, and electrochemical properties were studied to evaluate the effect of the preparation conditions on the materials when used as supercapacitor electrodes. The characterization results indicated that a suitable surfactant, reaction temperature and heating time could improve the electrochemical properties. The NiFe2O4 nanoparticles presented a capacitance of 113.6 F/g and a capacity retention of 83.3% after 2000 charge/discharge cycles. The NiO@NiFe2O4 composite material had a capacitance of 248.4 F/g and an electrochemical stability of 89.2% after 2000 cycles. Theoretical calculations were performed to provide more insight into the electrochemical performance.