Fast Electrochemical Storage Process in Sputtered Nb₂O₅ Porous Thin Films

The formation of a thin film electrode exhibiting high capacity and high rate capabilities is challenging in the field of miniaturized electrochemical energy storage. Here, we present an elegant strategy to tune the morphology and the properties of sputtered porous Nb₂O₅ thin films deposited on Si-based substrates via the magnetron sputtering deposition technique. Kinetic analysis of the redox reactions is studied to qualify the charge storage process, where we observe a non-diffusion-controlled mechanism within the porous niobium pentoxide thin film. To improve the surface capacity of the Nb₂O₅ porous electrode, the thickness is progressively increased up to 0.94 μm, providing a surface capacity close to 60 μAh·cm^-2 at 1 mV·s^-1. The fabrication of high energy density miniaturized power sources based on the optimized T-Nb₂O₅ films could be achieved for Internet of Things applications requiring high rate capability.