Micro-origami meets Zn batteries: Pushing energy storage boundary below 1 mm²

The development of tiny energy storage devices with high energy density is critical to realizing autonomous intelligent microsystems and small-scale robotic applications. In this presentation, I will explore the potential of zinc battery chemistries for sub-millimeter-scale energy storage, highlighting their advantages over conventional lithium-based systems. Zn batteries, with their superior air stability and seamless compatibility with microfabrication processes, offer significant promise in overcoming the challenges of miniaturization to sub-millimeter footprints. I will discuss recent innovations in using micro-origami technology to develop tiny Zn batteries, which have crushed the footprint limit of 1 mm², achieving a footprint capacity of more than 1 mAh/cm² and extending the boundaries to deep-submillimeter scale (< 0.1 mm²). Additionally, this talk will emphasize the material innovations for microfabrication techniques that have enabled Zn batteries to take center stage in the quest for reliable, efficient energy storage at sub-millimeter scales. I will highlight the development of different photolithographable polymer electrolytes to improve the cycling stability of Zn and therefore the lifetime of a full cell. Moreover, emerging battery chemistries such as cathode-free configuration, decoupled electrolyte design and halogen cathodes will be briefly discussed to show the potential of Zn batteries in advancing the performance of sub-millimeter batteries. Finally, I will demonstrate the proof-of-concept integration of sub-millimeter zinc batteries with micro-actuators, highlighting the significance of modulating zinc ion behaviour in an aqueous solution to simultaneously realize efficient actuation and energy storage.