Ultrafast Laser Drilling of 3D Porous Current Collectors for High-Capacity Electrodes of Rechargeable Batteries

High-capacity rechargeable batteries are crucial for portable electronics, electric vehicles, and smart power grids. High-quality porous Al current collectors with well-designed hole size and hole density are expected to strengthen lithium transportation as well as to accommodate volume variations during fast charging and discharging. Ultrafast femtosecond laser drilling is exploited in this paper to fabricate 3D porous current collectors with precisely controlled hole size and porosity. With optimized laser processing parameters, a series of high-quality porous Al foils with different hole diameters and porosities are designed, simulated, and prepared to investigate their influence on the battery performance of the LiFePO₄ electrode. The electrode using laser-drilled Al foil with a hole diameter of 60 μm and a porosity of 15% shows pretty high capacities at various charge/discharge rates. The performance improvement is ascribed to the large roughness and high surface area of the 3D Al foil, the strong connection between electrode materials and the porous current collector, the high loading density and efficient utilization of active materials, the good wettability and facile penetration of the electrolyte and, thus, the high Li⁺ diffusivity, and the buffering of volume/stress variation during charging/discharging in the 3D porous electrode.