Microneedle-assisted non-destructive and scalable structural engineering for high-performance dry-processed thick electrodes

Solvent-free dry-electrode processing has emerged as a promising method for electrode fabrication as it eliminates solvent handling and suppresses binder redistribution during drying, enabling high-loading electrode fabrication with reduced energy demand and carbon footprint. However, dry-processed thick electrodes typically suffer from limited electrolyte infiltration and sluggish through-thickness ion transport, which severely compromise rate capability and cycling stability. In this study, we fabricate high-loading electrodes via a solvent-free dry process and introduce a microneedle-assisted perforation strategy to overcome these transport limitations. A custom-engineered microneedle tool enables the non-destructive formation of vertically aligned microchannels with precisely controllable depths and pore densities, without inducing active-material ablation or thermal damage. By systematically tuning the contact conditions between the microneedle master and the electrode surface, we elucidate the deformation mechanisms governing perforation and achieve burr-free, well-defined channels with flat surface profiles. The resulting microchannels significantly reduce electrode tortuosity and promote rapid electrolyte infiltration, leading to markedly improved rate performance and long-term cycling stability compared with non-perforated dry thick electrodes. Furthermore, replication of the microneedle array onto a flexible sheet and its integration onto a cylindrical roll demonstrate compatibility with roll-to-roll processing, highlighting the scalability of this approach. Overall, this microneedle-assisted structural engineering strategy provides a scalable and production-ready pathway toward high-energy-density lithium-ion batteries.