“…Manganates are poorly conductive; thus, the specific capacitance is strongly dependent on the electrode thickness; extremely thin films show specific capacitance as high as ∼1000 F g –1 , , while films with practical mass loadings show moderate values, that is, ∼200 F g –1 . , While conductive additives such as acetylene black are added to the electrode to assist the conduction of electrons, the conductivity of manganese oxide can also be improved by doping with other metals. Doping birnessite with other transition metals such as Co, Mo, Ru, and so forth is an effective method to increase the electronic conductivity and leads to an increase in capacitance. − For example, cobalt-doped birnessite electrodes prepared by electrodeposition exhibit a specific capacitance of 170 F g –1 at 2 mV s –1 , which is almost 3 times higher than that of the nondoped birnessite MnO 2 . Ruthenium-doped MnO 2 nanosheets synthesized by exfoliation of Ru-doped birnessite-type K x MnO 2 have also shown promising results, showing a 1.4 times increase in specific capacitance by 10 mol % doping with Ru …”