Synthesis of T-Nb2O5 thin-films deposited by Atomic Layer Deposition for miniaturized electrochemical energy storage devices

Atomic Layer Deposition has been used to grow 30 to 90 nm-thick amorphous Nb2O5 films onto Pt current collectors deposited on Si wafer. While T-Nb2O5 polymorph is obtained by further annealing at 750 °C, the film thickness and the resulting electrode areal capacity are successfully controlled by tuning the number of ALD cycles. The electrochemical analysis reveals a lithium ion intercalation redox mechanism in the T-Nb2O5 electrode. An electrode areal capacity of 8 µAh cm-² could be achieved at 1 C, with only 40% capacity loss at 30 C (2 minutes discharging time). This paper aims at demonstrating the use of Atomic Layer Deposition method in the fabrication of Nb205-based on-chip micro-devices for Internet of Things (IoT) applications.