Short communication

Thin and flexible silicon anode based on integrated macroporous silicon film onto electrodeposited copper current collector

The integration of a macroporous Si (pSi) layer on an electrodeposited Cu current collector is proposed as a facile, low-cost and industrial-scalable procedure to elaborate efficient new anode material for lithium-ion batteries. The preparation process consists of i) formation of macropores on a Si wafer by electrochemical etching, ii) chemical deposition of Cu NPs on microstructured Si, iii) electroplating of a thick continuous Cu film, and iv) peeling of pSi–Cu film. The anode device is flexible and presents a total thickness, comprising the current collector, of 25 μm. SEM characterization shows the partial integration of the copper film inside the Si porous structure. Electrochemical impedance spectroscopy measurements showed this architecture enhances the electrical contact between the Cu current collector and the pSi due to the optimized interface of the two materials. A specific capacity of 1360 mAh g ⁻¹ in EC/DMC LiPF ₆ 1 M is achieved at low galvanostatic discharge current (0.2 A g ⁻¹ ). Even during cycling at a high current density of 1.8 A g ⁻¹ , the macroporous silicon anode was stable, demonstrating a specific capacity of 750 mAh g ⁻¹ twice as large as graphite based anodes.