Enhancing Electrochemical Performance of Stretchable/Flexible Li‐Ion Microbatteries by Tuning Microstructured Electrode Dimensions

Increasing surface area between electrodes and electrolytes drastically has proven to improve electrochemical performances of microbatteries. 3D surface enhancement owing to the design of micropillar electrodes has permitted to fulfill this need while maintaining the same footprint area. Lithium nickel manganese oxide (cathode) and Lithium titanate (anode) micropillars with different sizes are successfully fabricated on aluminum foils by laser ablation technique and are then separated by a polymer electrolyte to form stretchable lithium‐ion microbatteries. The electrochemical performance of full batteries composed of different micropillar sizes is studied in detail. The importance of controlling the width of micropillars is demonstrated and correlated with a simple theoretical model to optimize the battery properties. It is also shown that areal capacity values can be enhanced by improving the electrode/electrolyte interfaces using a simple treatment under vacuum. The influence of micropillar size on the electrochemical performance of stretchable Li‐ion microbatteries is investigated. In accordance with the theoretical predictions, batteries composed of micropillars of 25 µm width and spacing reveal the best characteristics. A significant increase of capacity is attained, thanks to a better electrode/electrolyte interface achieved by a treatment of microstructured electrodes in vacuum.