Effects of Electrolytic Copper Foil Roughness on Lithium-Ion Battery Performance

Improving the interfacial properties between the electrode materials and current collectors plays a significant role in lithium-ion batteries. Here, four kinds of electrolytic copper foils with roughness (Rz) values of 1.2, 1.5, 2.2, and 2.8 μm were prepared via an electropolishing technique. Reducing the roughness of the electrolytic copper foil can effectively improve the wettability of the anode slurry. The electrolytic copper foil with a roughness value of 1.2 μm shows the best coating uniformity of the graphite anode slurry. The battery with this electrolytic copper foil (Rz = 1.2 μm) as the current collector exhibits fifth-cycle capacities of 358.7 and 102.5 mAh g−1 at 0.2 and 3.0 C, respectively, showing excellent rate capability. In addition, at 0.5 C, the battery exhibits an initial discharge capacity of 319.5 mAh g−1 and a 100th-cycle capacity retention rate of 98.1%, demonstrating a high level of cycling performance. These results indicate that reducing the roughness of electrolytic copper foil can provide a feasible route to improve the performance of lithium-ion batteries.