Millimeter-thick microsupercapacitors with linear thickness-scaling of energy and power densities via multilayer electron highway architecture.

The relentless miniaturization of microelectronics demands energy storage systems with ultrahigh energy and power densities in ultracompact footprints. Microsupercapacitors (MSCs) are promising due to their rapid charge-discharge capabilities, but conventional electrode architectures suffer from a trade-off between energy and power density as thickness increases, exacerbated by electron transport resistance and mechanical instability. Here, we present a paradigm-shifting, truly millimeter-thick (up to 1.2 mm), high-aspect-ratio (7:1), three-dimensional microelectrode architecture that fundamentally decouples electron transport distance from electrode thickness. By roll-to-roll calendering of alternating multilayer current collectors and electrode films, we achieve precisely aligned multilayer structures with total thicknesses exceeding 1 mm, specifically demonstrating a 1.2 mm-thick, 9-layer device in an ultracompact footprint, followed by precision laser engraving to define interdigitated gaps below 180 µm, establishing a parallel electron transport network. Therefore, the architecture enables linear scaling of both energy and power density with thickness, delivering a peak energy density of 1733 µWh cm