MnO(2)@Corncob Carbon Composite Electrode and All-Solid-State Supercapacitor with Improved Electrochemical Performance

Two corncob-derived carbon electrode materials mainly composed of micropores (activated carbon, AC) and mesopores/macropores (corncob carbon, CC) were prepared and studied after the anodic electrodeposition of MnO(2). The capacity of the MnO(2)/activated carbon composite (MnO(2)@AC) electrode did not noticeably increase after MnO(2) electrodeposition, while that of the MnO(2)/corncob carbon composite (MnO(2)@CC) electrode increased up to 9 times reaching 4475 mF cm(−2). An asymmetric all-solid-state supercapacitor (ASC) was fabricated using AC as the anode, MnO(2)@CC as the cathode, and polyvinyl alcohol (PVA)/LiCl gel as the electrolyte. An ultrahigh specific capacitance of 3455.6 mF cm(−2) at 1 mA cm(−2), a maximum energy density of 1.56 mW h cm(−2), and a long lifetime of 10,000 cycles can be achieved. This work provides insights in understanding the function of MnO(2) in biomass-derived electrode materials, and a green path to prepare an ASC from waste biomass with excellent electrochemical performance.