2.6 V Aqueous Symmetric Supercapacitors Based on the Phosphorus-doped TiO2 Nanotube Arrays
Increasing the voltage window of electrode material is effective to improve the energy density of aqueous symmetric supercapacitors. Here in, a novel aqueous symmetric supercapacitor equipped a high cell voltage window of 2.6 V was assembled by P-doped TiO2 nanotube arrays on Ti sheet. The arrays get a wide potential range about 1.2 V as the cathode, and a stable wide potential range of 1.4 V as the anode was also obtained. These wide potential windows in cathode and anode render the symmetric supercapacitor with a very large working voltage window reached to 2.6 V, and thus high volumetric energy density (1.65 mWh cm-3). These results suggest P-doped TiO2 nanotube arrays can be a promising candidate for the energy storage device.