Fe(CN)63- ion-modified MnO2/graphene nanoribbons enabling high energy density asymmetric supercapacitors

Due to its high theoretical specific capacitance and high oxygen evolution potential, MnO2 has been considered as a promising positive electrode material for high-energy asymmetric supercapacitors (ASCs). However, the search for MnO2 positive electrodes with high specific capacitance and excellent rate performance for ASCs remains challenging. Herein, for the first time we report a novel strategy for the synthesis of Fe(CN)(6)(3-) ion-modified MnO2/graphene ribbons (m-MnO2/GRs) as the positive electrode for high energy density ASCs. Benefiting from vertically aligned MnO2 grown on the interconnected graphene ribbon and Fe(CN)(6)(3-) ion modification, the m-MnO2/GR exhibits a high specific capacitance of 435 F g(-1), excellent rate capability and cycling stability. More importantly, the assembled m-MnO2/GR//GR ASC exhibits a high energy density of 57.8 W h kg(-1) at a power density of 1.2 kW kg(-1), as well as outstanding cycling stability with 100% capacitance retention after 10 000 cycles. More importantly, such a device can be charged/discharged within 0.79 s in an ultrafast manner to deliver a high specific energy of 10.5 W h kg(-1) at an ultrahigh specific power of 48 kW kg(-1). Thus, our strategy could be possibly used for the design and fabrication of new energy storage devices with high energy and power densities for future applications.