Fully 3D Printed Aqueous Zinc Ion Batteries for Wearable Electronic Devices

Rechargeable Zinc Ion Batteries (ZIBs) based on aqueous electrolytes are among the most promising beyond-lithium energy storage systems, featuring large volumetric capacity, low cost and outstanding safety. The use of Earth-abundant, non-hazardous electrode materials and water-based electrolytes makes ZIBs ideal power sources to meet the growing energy demand of wearable and portable electronics. Nonetheless, the large-scale commercialization of rechargeable zinc ion batteries is still hindered by significant technological challenges, primarily associated with the low electrochemical reversibility of such systems.<br/><br/>The structural re-design of the electrode architectures is an effective strategy to prolong the cycle life of ZIBs, reducing the local current density at the interface with the electrolyte and promoting a uniform and reversible zinc plating. 3D Printing is a sustainable manufacturing process that can be employed to fabricate electrodes with customized design, <i>via</i> the layer-by-layer deposition of suitable inks. The rationally-designed structure of 3D Printed electrodes provides enhanced electrochemical stability and superior specific capacity, simultaneously ensuring uninterrupted charge transport pathways and fast charge transfer inside the device.<br/><br/>Here, we present the fabrication of interdigitated Zinc Ion Batteries entirely <i>via</i> the 3D Printing of aqueous ink formulations, specifically tailored for the anode, cathode and gel electrolyte deposition. We electrochemically characterize the battery and we demonstrate it can power commercial wearable devices. We identify that the 3D architecture of the electrodes is crucial in increasing the reversibility of the printed battery, and investigate the degradation processes and electrochemical failure through <i>post-mortem</i> characterization.