A Sub‐Square‐Millimeter Microbattery with Milliampere‐Hour‐Level Footprint Capacity

Abstract As substantial progress has been made to miniaturize intelligent microsystems to the sub‐square‐millimeter scale, there is a desperate need to move beyond existing microbattery technologies to offer adequate energy at the same footprint. A micro‐origami technology able to wind up a flat layer stack into a Swiss roll presents a promising approach in this regard because it mimics the most successful way to make energy‐dense full‐sized batteries. Here, an on‐chip Swiss‐roll current collector made via the micro‐origami process is developed and it is infused with a MnO₂ slurry comprising a zincophilic binder. The zincophilic binder layer enhances zinc ion transportability and suppresses MnO₂ dissolution. The MnO₂ Swiss‐roll microelectrode is used to create an on‐chip microbattery with a small electrode footprint area of 0.75 mm², which shows a footprint capacity up to 3.3 mAh cm^–2. The microbattery demonstrates a reversible capacity of more than 1 mAh cm^–2 for 150 cycles. The battery stability can be improved to over 600 cycles at a 50% depth of discharge. An on‐chip integration of a microsystem with the microbattery is demonstrated. The microbatteries set foot in the untrodden sub‐square‐millimeter area providing adequate energy for ever more miniaturized intelligent microsystems.