Preparation and electrochemical kinetics properties of FeO@C/MAX composites
FeO@C/MAX(FCM)composites were prepared from calcination of α-Fe2O3@C with titanium powder and aluminum powder at high temperature.The structure,composition and morphology of FCM composites at different molar ratios of Ti/C and Al/C were characterized by XRD,SEM and TEM.Moreover,the pseudo-capacitance ratio of FCM composites was quantitatively calculated by electrochemical kinetics analysis with the possible charge storage mechanism deduced.The results showed that the content of MAX phase(Ti2AlC and Ti3AlC2)in the FCM composites was changed with the increment of Ti/C molar ratio as well as Al/C molar ratio,but α-Fe2O3 transformed into unstable FeO.According to data from electrochemical tests,the maximum specific capacitance of FCM-312 prepared with n(Ti)∶n(Al)∶n(C)=3∶1∶2 was 125.09 F/g at a sweep rate of 1 mV/s,approximately 4.76-fold higher than that of α-Fe2O3@C.Some MAX phases of FCM composites underwent redox reaction during the electrochemical process,which provided conditions for rapid electron transport between ions,and increased the pseudo-capacitance ratio of FCM composites.Among them,the pseudo-capacitance ratio of FCM-312 sample at 10 mV/s scanning rate reached 22.12%.