Directly grown Si nanowire arrays on Cu foam with a coral-like surface for lithium-ion batteries†
In order to mitigate the drastic volumetric expansion (>300%) of silicon (Si) during the lithiation process, we demonstrate the synthesis of novel Si nanowire arrays (n-SNWAs) with a coral-like surface on Cu foam via a one-step CVD method, in which the Cu foam can simultaneously act as a catalyst and current collector. The unique coral-like surface endows n-SNWAs with a high structural integrity, which is beneficial for enhancing their electrochemical performance. In addition, the as-prepared n-SNWAs on Cu foam can be directly applied as the anode for lithium-ion batteries (LIBs), exhibiting a very high reversible discharge capacity (2745 mA h g−1 at 200 mA g−1) and a fast charge and discharge capability (884 mA h g−1 at 3200 mA g−1), which is much higher than the conventional SNWAs (c-SNWAs, only 127 mA h g−1 at 3200 mA g−1). Meanwhile, they deliver an improved cycling stability (2178 mA h g−1 at 400 mA g−1 after 50 cycles). More significantly, the as-synthesized n-SNWAs on Cu foam also possess a superior specific areal capacity of 4.1 mA h cm−2 at 0.6 mA cm−2. Such excellent electrochemical performance is superior, or at least comparable, to the best report for Si anode materials. Combining the cost-effective and facile preparation method, the present n-SNWAs on Cu foam can serve as a promising anode for LIBs.