Decoupling Electrochemical Performance from External Pressure via Mechanically Interlocked 3D Interfaces for Ultra-low-pressure Supercapacitor Pouch Cells

Abstract

Supercapacitor pouch cells typically require substantial external stack pressure (typically >2 MPa) to maintain intimate internal interface contact. However, the heavy packaging modules introduce significant inactive mass, reducing system-level energy density. Herein, we report a two-step aligned 3D imprinting strategy that fundamentally decouples electrochemical performance from external compression. By engineering a mechanically interlocked structure, the compaction force is precisely directed toward the interfaces between the active particles, as well as between the particles and the current collector. This prevents lateral slippage, achieving ultra-low internal electrode resistance and conformal interface contact. Consequently, compared with planar electrodes, imprinted electrodes exhibit a 14.3-fold lower interfacial resistance and a 2.7-fold lower equivalent series resistance even under 0.3 MPa stack pressure, delivering an unprecedented average power density of 285 kW kg–1 at 1 mg cm–2 and 28.4 kW kg–1 at 5 mg cm–2. Notably, pouch cells based on 3D-D electrodes sustain 100,000 cycles with 99% capacitance retention, benefiting from the mechanically stabilized interface and the suppressed resistance evolution. Furthermore, this paradigm is compatible with roll-to-roll manufacturing processes, providing a versatile and scalable approach for the next generation of high-power, lightweight, and ultra-low-pressure supercapacitor systems.