Fabrication of manganese oxides/carbon composites for high energy density asymmetric supercapacitor.

Low conductivity of metal oxide electrode and low specific capacitance of carbon electrode restrict the further commercial application of supercapacitors. Manganese oxides/carbon composites were prepared by a simple method using homemade porous carbon and KMnO 4 as raw materials. The composites have both high capacitance of metal oxides and high conductivity of carbon due to Mn-O-C interaction. The optimized composite electrode exhibited an incredible ultra-high specific capacitance of 550, 520, 481, 402, and 318 F/g at the current densities of 1, 2, 3, 5, and 10 A/g, respectively. Moreover, the assembled asymmetric supercapacitor (ASC) device obtains an astonishing energy density of 50.2 Wh/kg at a power density of 800 W/kg, while 90.5 % capacitance after 10,000 cycles is still maintained. Meanwhile, ASC devices show great potential applications in energy storage, such as lighting 35 lights and running an electronic stopwatch. This material will promote the development of manganese/carbon composite supercapacitors for its simple preparation methods, ultra-high performance, and is expected to be a promising candidate for commercially large-scale applications. [Display omitted] • Manganese oxides/carbon composite with splendid specific capacitance was prepared by a simple method. • The assembled asymmetric supercapacitor (ASC) device obtains an astonishing energy density of 50.2 Wh/kg (800 W/kg). • The ASC device shows excellent cycling stability with a capacitance remaining of 90.5 % after 10,000 cycles. [ABSTRACT FROM AUTHOR]