Laser-Architected Vertical Micro-Channel Arrays in Thick Graphene Electrodes for High-Rate Zinc-Ion Hybrid Capacitors

Abstract

Thick electrodes are pivotal for high-energy-density storage but typically suffer from kinetic limitations as thickness increases. Herein, we report a template-free, laser-enabled manufacturing strategy to construct monolithic thick graphene electrodes with a thickness of approximately 500 μm featuring arrayed vertical channels. Utilizing the intrinsic thermal localization effect of the porous framework, 1064 nm laser pulses precisely engineer low-tortuosity vertical ion transport pathways within a commercial-level mass-loading matrix (> 10 mg/cm 2 ). Multi-scale characterization reveals that the laser ablation induces a site-selective functionalization: while the bulk conductive skeleton remains structurally and chemically intact to ensure high electronic conductivity, the channel edges are locally activated with abundant defects and highly hydrophilic sites. This hierarchical architecture transforms the diffusion kinetics from a macroscopic thickness scale to a microscopic radial diffusion scale, successfully facilitating electrolyte penetration into previously kinetically inaccessible deep-seated active sites. Consequently, the optimized electrode achieves a superior areal capacitance of 434.0 mF/cm 2 at 20 mA/cm 2 with a high rate retention of 62.9%. The assembled zinc-ion hybrid capacitor delivers a high areal energy density of 166.8 μWh/cm² and robust cyclability, maintaining 95.1% capacity retention over 20,000 cycles. This work offers an efficient geometric optimization pathway for next-generation high-loading electronics.