GLAD-Derived Silicon Nanoarrays on Electrochemically Polished Cu Foil: A Promising Anode for High-Performance Lithium-Ion Batteries

Nanostructured silicon (Si) anodes with various dimensions (0- or 1D) are widely explored in the manufacturing of high-energy-density lithium-ion batteries (LIBs) to mitigate volume expansion during cycling. However, most of them suffer from multiple issues, such as phase impurity, inhomogeneity in particle size, and poor mechanical strength, resulting in poor rate capability, cycle performance, and Coulombic efficiency. In this work, a modified physical vapor deposition technique, known as the glancing angle deposition (GLAD) method, is utilized to produce pure Si nanospring arrays on Cu foil. The nanospring architecture, with controlled dimensions, facilitates Li⁺ diffusion throughout the amorphous Si and offers good rate performance. In this case, electrochemical polishing of Cu foil has played a pivotal role to achieve a very high specific capacity of 2800 mAh g^-1 at 300 mA g^-1 and a very good rate capability of up to 4500 mA g^-1. The electrochemical polishing facilitates uniform deposition of the Si nanosprings on the Cu surface and offers better structural robustness compared to the unpolished one.