Cascaded Spatial Confinement Enables Simultaneous Ultrahigh Energy and Power Densities in Planar Micro-Supercapacitors

Planar microsupercapacitors (P-MSCs) with high power density and conformal configurations could provide on-chip power supply in the design of highly integrated electronics. However, achieving a breakthrough in overall energy within a finite footprint requires establishing an effective structure-performance relationship. Here, we present a cascaded spatial confinement strategy to construct a 3D interlocked P-MSC that couples force fields with charge transport/storage behavior, enabling ion-electron enrichment. Laser-etched pyramid microarrays on graphite current collectors create capillary forces that confine both electrode slurry and electrolyte to build a compact conduction network, while establishing a robust ion-electron interaction interface, significantly facilitating ion accessibility and kinetics. Using Zn//active carbon (AC) P-MSC as an example, the strategy boosts active material utilization by over 2-fold, and delivers an outstanding energy density of 117.5 mWh cm^–3 and a power density of 2382.0 mW cm^–3, exceeding those reported for Zn//AC P-MSCs by several to tens of times, and surpassing nearly all existing Zn-based P-MSCs in areal performance. The approach demonstrates reliable universality across various P-MSC systems (eight types are verified). Integrated devices show notable advantages in powering miniaturized electronics and flexible displays, possessing a voltage output approximately 4.7 times that of a same-sized dry battery, and are also configured as emergency power chips to charge smartphones.