Towards High-Performance, Low-Temperature Solid Oxide Cells with Vertically Aligned Nanocomposite Films

Low temperature micro solid oxide cells (µSOCs) represent a key technology in next-generation energy devices for portable applications, offering the highly efficient conversion of electrical to chemical energy (e.g. hydrogen), and vice versa. To date however, the widespread implementation of µSOCs, and therefore the effective use of hydrogen as a portable energy storage solution, has been prohibited by excessive polarisation resistances at the device electrodes, despite significant progress in materials design.<br/> <br/>Vertically aligned nanocomposite (VAN) films have been a leading class of materials in recent performance enhancements in µSOC design, and in this work we further explore the growth and characterisation of such VAN films. State-of-the-art fluorite and perovskite materials are combined in each of the anode, electrolyte, and cathode layers and the enhancement rendered by the novel VAN structure quantified in each case by electrochemical impedance spectroscopy (EIS). Moreover, films are grown on both single-crystal and more commercially viable polycrystalline/amorphous substrates. This allows for a detailed study of the VAN growth mechanisms for materials of differing crystal structures, while also giving an improved understanding of the importance of crystalline perfection in thin-film µSOC device performance.<br/> <br/>Future progress in low-temperature µSOC technology will rely heavily on a detailed understanding of the growth mechanisms of state-of-the-art nanostructured materials, such as VAN thin films. By building such an understanding and quantifying the performance enhancements resulting from a wide variety of VAN structures, this study represents an important step towards the realisation of efficient low-temperature µSOCs for portable applications.