Abstract
A simple, binder-free fabrication of high capacitance electrodes based on manganese dioxide (MnO2) thin films is reported. The 3D structure of these electrodes significantly improves the areal capacitance of the MnO2 thin films up to 670 mF cm−2 in aqueous electrolyte, which is 4.5 times higher than the best reported capacitance of 3D electrodes thus far. This capacitance is on the same order of magnitude as that of a bulk carbon electrode. Moreover, the 3D MnO2-based electrode exhibits a stable cycling behavior for more than 15 000 cycles.