Microbatteries with twin-Swiss-rolls redefine performance limits in the sub-square millimeter range.

To maintain the downscaling of microelectronic devices with footprints less than one square millimeter, next-generation microbatteries should occupy the same area and deliver adequate energy for running a new generation of multi-functional microautonomous systems. However, the current microbattery technology fails in accomplishing this task because the micrometer-sized electrodes are not compatible with on-chip integration protocols and technologies. To tackle this critical challenge, an on-chip Swiss-roll microelectrode architecture is employed that exploits the self-assembly of thin films into ultra-compact device architectures. A twin-Swiss-roll microelectrode on a chip occupies a footprint of 0.045 mm 2 and delivers an energy density up to 458 μW h cm -2 . After packaging, the footprint of a full cell increases to 0.11 mm 2 with a high energy density of 181 μW h cm -2 . The volumetric energy density excluding the chip thickness is 16.3 mW h cm -3 . These results open opportunities for deploying microbatteries as energy and power sources to drive smart dust microelectronics and microautonomous systems.