Self-organized amorphous TiO2 nanotube arrays on porous Ti foam for rechargeable lithium and sodium ion batteries

Self-organized amorphous TiO 2 nanotube arrays (NTAs) were successfully fabricated on both Ti foil and porous Ti foam through electrochemical anodization techniques. The starting Ti foams were fabricated using ARCAM's Electron Beam Melting (EBM) technology. The TiO 2 NTAs on Ti foam were used as anodes in lithium ion batteries; they exhibited high capacities of 103 μAh cm −2 at 10 μA cm −2 and 83 μAh cm −2 at 500 μA cm −2 , which are two to three times higher than those achieved on the standard Ti foil, which is around 40 μAh cm −2 at 10 μA cm −2 and 24 μAh cm −2 at 500 μA cm −2 , respectively. This improvement is mainly attributed to higher surface area of the Ti foam and higher porosity of the nanotube arrays layer grown on the Ti foam. In addition, a Na-ion half-cell composed of these NTAs anodes and Na metal as the counter electrode showed a self-improved specific capacity upon cycling at 10 μA cm −2 . These results indicate that TiO 2 NTAs grown on Ti porous foam are promising electrodes for Li-ion or Na-ion rechargeable batteries.