Research on the effects of electrolyte on the electrochemical performance of Fe3 O4/graphene composites.

Fe3 O4/graphene composites with Fe3 O4 nanosheets vertically and uniformly grown on the surface of graphene are prepared by solvothermal method. XRD, BET, SEM, TEM and other characterization methods are used to characterize the structure of the composites. CV and GCD are used to test the electrochemical performance of the composites using KOH, Na2SO3 and Na2SO4 aqueous solution as electrolyte. The effects of the type and concentration of electrolyte on the electrochemical performance of Fe3 O4/graphene composites are analyzed. The results show that different types of electrolytes have different ionic radii, and the size of the ionic radius affects the insertion/extraction of ions in the electrode material, so the capacitance of Fe3 O4/graphene composites in different types of electrolytes behaves differently. The order of specific capacitance of Fe3 O4/graphene composites in three different electrolytes from large to small is: KOH electrolyte> Na2SO3 electrolyte> Na2SO4 electrolyte, and the specific capacitance reaches the maximum in 0.9 mol/L KOH electrolyte (330 F/g, current density ls 0.4 A/g). Different concentrations of KOH electrolyte have different viscosities and electrical conductivity. The viscosity and conductivity of the electrolyte will affect the migration speed of ions, further affecting the capacitance performance of Fe3 O4/graphene composites. [ABSTRACT FROM AUTHOR]