Three-Dimensional Nanopore γ′-V2O5 Architectures Enabling Stable, Long-Life, High-Power Sodium-Ion Microbatteries

Abstract A three-dimensional nanoscale architecture originating from semiconductor manufacturing offers a powerful route to overcome ion-transport limitations in microscale electrochemical systems. Here, we report a sodium-ion microbattery array based on a coaxial γ’-V2O5/Pt nanotube architecture embedded within anodic aluminum oxide (AAO) nanopores, forming vertically aligned nanotubular electrodes conformally integrated with Pt nanotube current collectors. This nanoconfined geometry shortens Na+ diffusion pathways, enhances charge-transfer kinetics, and maintains electronic conduction across the microbattery array. The resulting device delivers a high areal capacity of 44 μAh cm–2 (corresponding to one Na+ per γ’-V2O5) at 1/10 C, excellent rate capability up to 2 C, and exceptional cycling stability with 80% capacity retention after 720 cycles. Cyclic voltammetry analyzed by both Trasatti's and Dunn's methods reveals that 66–69% of the stored charge arises from surface-dominated processes enabled by the nanotube architecture, compared to only 17–25% in planar films. The stark performance contrast between the nanoscale nanotube geometry and micron-scale planar controls suggests a fundamental length-scale dependence of sodiation kinetics, with implications for particle size selection in conventional sodium-ion battery electrodes. These results demonstrate that semiconductor-derived 3D architectures can be directly translated to sodium-ion systems, enabling high-power, long-life microbatteries and establishing a generalizable platform for nano-ionic device engineering.