Aerosol-deposited freestanding Na3V2(PO4)3 thin-film microbattery

High energy density on chip microbatteries that can provide necessary power capability is highly sought to power miniaturized and smart electronics. Currently, various thin-film electrode fabrication methods are struggling to upscale the production. Herein, a thin all-electrochemical-active sodium-ion electrode consisting of Na3V2(PO4)3 and carbon is prepared using aerosol deposition method without postthermal treatment. The freestanding Na3V2(PO4)3 thin film exhibits an increase in charge transfer efficiency, higher sodium ions diffusion coefficient, and a smaller overpotential than conventional bulk electrode. Consequently, the thin-film half-cell delivers a high reversible areal capacity of 32.2 μAh/cm2, a high energy density of 0.106 mWh/cm2, at 96.4 μA/cm2, and an excellent cyclic stability (88.6% after 1000 cycles at 100 μA/cm2). In addition, the full cell delivers a high initial energy density of 213.6 Wh/kg at 15.8 W/kg. This work presents a viable process to prepare a high-performance electrode thin film for practical application. [Display omitted] •Composite Na3V2(PO4)3/C thin electrode film fabricated using aerosol deposition method.•High charge transfer efficiency and smaller overpotential in the microbattery.•An areal specific capacity of 32.2 μAh/cm2 at 96.4 μA/cm2 and 88.6% capacity retention after 1,000 cycles.•Sodium-ion microbattery shows a high initial discharge energy density of 213.6 Wh/kg at 15.8 W/kg.