Development of an inkjet printer for electrolyte layers of oxygen ion batteries

Abstract

Oxygen-ion batteries are a newly developed all-solid-state energy storage device that could help balance the load of variable-power, renewable energy sources that are increasingly integrated into power grids. Different processes are discussed to fabricate these batteries on large scale, including inkjet printing. This work investigates the development and application of an inkjet printer for the task of printing the electrolyte layer, consisting of yttria stabilized zirconia (YSZ).Development and implementation involved defining requirements, component selection as well as electrical, mechanical and software design. A detailed description of the design decisions, the components used and the implementation is given with the intention to assist in reproducing this printer, a similar one or parts there of. The main elements of the built printer are the printhead, printhead drive electronics and associated firmware, an ink supply system, the motion stage, vision systems to inspect and optimize the printing process, as well as software to control and operate the printer. Solvent-based inks containing YSZ particles were created and used to print YSZ layers with the implemented printer onto single crystal substrates. The printed layers were sintered and then characterized using optical and electron microscopy, profilometer measurements, X-ray diffraction (XRD) as well as electrochemical impedance spectroscopy (EIS). While printing various patterns with the ceramic particle-filled ink was successful, the resulting layers with a thickness of up to 4 μm had substantial porosity, even though up to 200 layers were deposited on top of each other. Measurements indicated that density and ionic conductivity was not yet sufficient to use the printed layers as electrolyte layers for batteries. However, the detected activation energy was that of ion conduction in YSZ. However, based on the detected activation energy, it could be concluded that the conduction process is the desired oxide ion motion in YSZ. Moreover, it is expected to achieve the required layer properties for use as an electrolyte by further improving the ink composition. Discussing the development and application of the printer, guidelines were identified that can be used for improvement or selecting/designing a future printer for this specific task. These include printhead properties like water-based ink compatibility or recirculating ink supply, repeatability of the motion stage related to droplet size, benefits of the camera systems and the use of an enclosure.