Ozone-Based Atomic Layer Deposition of Crystalline V2O5 Films for High Performance Electrochemical Energy Storage

A new atomic layer deposition (ALD) process for V 2 O 5 using ozone (O 3 ) as oxidant has been developed that resulted in crystalline V 2 O 5 thin films which are single-phase and orthorhombic on various substrates (silicon, Au-coated stainless steel, and anodic aluminum oxide (AAO)) without any thermal post-treatment. Within a fairly narrow temperature window (170–185 °C), this low temperature process yields a growth rate of ∼0.27 Å/cycle on Si. It presents good uniformity on planar substrates. Excellent conformality enables deposition into high aspect ratio (AR) nanopores (AR > 100), as needed for fabrication of three-dimensional (3D) nanostructures for next generation electrochemical energy storage devices. V 2 O 5 films obtained using O 3 -based ALD showed superior electrochemical performance in lithium cells, with initial specific discharge capacity of 142 mAh/g in the potential range of 2.6–4.0 V, as well as excellent rate capability and cycling stability. These benefits are attributed primarily to the crystallinity of the material and to fast transport through the thin active storage layers used.