In situ hydrothermal growth of manganese hexacyanoferrate with Ni foam as the sacrificing template for high-performance asymmetrical supercapacitor

In situ growth of manganese hexacyanoferrate nanostructure (Mn-HCF) on Ni foam is achieved by simply heating Ni foam in the acidic solution containing KMnO4 and K3Fe(CN)(6) at 120 degrees C. Ni foam is used not only as the current collector but also as the reducing agent for the reduction of both KMnO4 and K3Fe(CN)(6). In acidic medium, MnO(4)(- )is reduced to Mn2+ while Fe(CN)(6)(3-) is reduced to Fe(CN)(6)(4-). The produced Mn2+ and Fe(CN)(6)(4-) subsequently react with each other to produce Mn-2[Fe(CN)6] center dot 0.5H(2)O (Mn-HCF). Mn-HCF supported on Ni foam (Mn-HCF/Ni foam) is used as a binder-free electrode for supercapacitor, which exhibits high areal capacitance and long cycling life. The asymmetrical supercapacitor (ASC) fabricated with Mn-HCF/Ni foam and activated carbon (AC) as the positive and negative electrodes, respectively, presents a high energy density of 8.84 W h m(-2) at power density of 75.3 W m(-2), implying the great application prospect of Mn-HCF/Ni foam.