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High-capacity rechargeable batteries are crucial for portable electronics, electric vehicles, and smart power grids. Highquality 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 LiFePO 4 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.

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High orientation consistency and adjustable convex width of the low-spatial-frequency laser-induced periodic surface structures (LSFLs), crucial to the functional surface characteristics, have remained elusive. This paper proposes a new method to fabricate LSFLs with high orientation consistency on the rough surface of titanium by combining laser polishing and laser induction with LSFLs with a tunable convex width via laser melting as the post-treatment. Picosecond pulses trains with a 50-ns interval are applied to regulate the thermal incubation effect and achieve laser polishing and laser nanoscale melting. The melting time of titanium for laser polishing and laser nanoscale melting is determined to be on a microsecond time scale and around 100 ns, respectively. Experimental studies show that the surface texture of titanium lowers the orientation consistency of LSFLs and its divergence angle is 30°. Picosecond pulses with a sub-pulse number of three are applied to achieve surface polishing and the formation of the rudiment of the LSFLs, followed by the picosecond laser induction. As a result, the divergence angle of LSFLs decreases from 30° to 12°. On this basis, aiming at the problem of the narrow adjustability of the convexity ratio of LSFLs, a nanoscale melting processing method based on picosecond pulse trains with a sub-pulse number of four is proposed, and LSFLs with the tunable convexity ratios from 0.3 to 0.87 are obtained.