Fabrication of low-tortuosity thick electrodes with low material loss by temporally shaped ultraviolet femtosecond laser

Conventional battery electrodes exhibit high tortuosity, which severely impedes ion transport. This limitation restricts electrode thickness, decreases power density, and shortens battery lifetime. Fabricating through-holes can reduce tortuosity, but existing methods are generally complex with poor space utilization. Here, an array of high-density through-holes are fabricated by temporally shaped ultraviolet femtosecond laser. Using this technique, we achieve a 47:1 aspect ratio (6 μm in diameter), ensuring low material loss (<1%) for 280 μm-thick LiFePO₄ (LFP) electrodes. The through-hole array reduces tortuosity of LFP thick electrodes by 19.1% (30 mg cm^-2), 19.0% (40 mg cm^-2), and 20.2% (60 mg cm^-2), improving the specific energy density of batteries by 9.39%, 12.27%, 17.39% at 1 C, 1.5 C, and 2 C, respectively. It also boosts LFP power density by 100%-200% and doubles the cycling lifetime. This work demonstrates an effective approach for fabricating low-tortuosity thick electrodes, enhancing comprehensive performance of batteries.