High-rate and excellent-cycle performance Li₄Ti₅O₁₂ electrodes with 3D porous copper foils as current collectors fabricated using a femtosecond laser processing strategy

Owing to their excellent structural superiorities of large storage space, high specific surface area and reduced volume expansion during battery charge and discharge cycles, 3D porous current collectors have received much concern in the anode of lithium-ion batteries. However, reasonable designing and efficient manufacturing of 3D porous copper foils as current collectors (PCFCCs) remain a great challenge due to the small thickness, soft texture, and variability of copper foils. These material characteristics make it hard to manufacture 3D micro-structure on copper foils and impede the practical application of lithium-ion batteries in more fields. Herein, an efficient and effective strategy is reported to enhance the electrochemical performance of Li₄Ti₅O₁₂ (LTO) electrodes via rationally designing and manufacturing 3D porous copper foils as current collectors. As a result, the 3D PCFCCs based LTO electrode displays low electrode polarization, excellent-cycle performance and ultra-high rate capacity. Moreover, the structures of various 3D PCFCCs are systematically studied for the first time, the design of 3D PCFCCs is optimized, and the mechanism of improving battery performance is explored. In addition, the proper micro-nano-pore-structures can facilitate electrolyte penetration and the solvated Li⁺ transport, and the excellent Li⁺ transmission ability of 3D PCFCCs is verified by simulation.