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

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 mm(2), 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.