Unlocking the potential of La-doped iron oxide @graphene oxide and ionic liquid-based asymmetric supercapacitor

Herein, lanthanum-doped iron oxide-integrated graphene oxide (10%La-Fe2O3@GO) as an anode and beta-MnO2 as a cathode material were successfully obtained via a facile hydrothermal method. The 10%La-Fe2O3@GO shows excellent electrochemical performance due to doping of rare earth La3+ metal ions in the Fe2O3@GO, providing abundant active sites. The 10%La-Fe2O3@GO was operated at a high potential window (-1.2 V) with an excellent specific capacitance (Cs) of 682.3 F/g at 1 A/g current density and capacitance retention of 83% over 5000 cycles. Moreover, the configured MnO2//Na2SO4//10%La-Fe2O3@GO aqueous device (Aq-ASC) was operated at a potential window of +1.6 V and delivered a maximum energy density of 19.5 Wh/kg at 0.9 kW/kg power density with Cs of 62.5 F/g at 1 A/g current density. Also, this device exhibited 87% retention over 5000 cycles. The quasi-solid state ionic liquid-based [BMIM][PF6] configuration of MnO2//[BMIM][PF6]//10%La-Fe2O3@GO (Iq-ASC) at a potential window of +4 V delivered a maximum energy density of 104.2 Wh/kg at 270.2 W/kg with Cs of 46.9 F/g at 0.1 A/g; this device is a perfect model for heavy-duty applications and hybrid vehicles due to ability to its adequate energy density at high-power density.