Improved electrochemical performance of nanostructured Si-based films modified by chemical etching

Chemical etching is introduced into the nanocones array supported silicon films to improve the lithium storage properties for Li-ion batteries. With the directional removal of some silicon, enough space is left between adjacent Si nanopillars. The Ni nanocones array enhances the electron conductivity and the interfacial strength to facilitate the electron collection and avoid the delamination. The space accommodates the volume expansion and allows the penetration of electrolyte into the inner of the electrode. This new type of nanostructured Si anodes delivers a high discharge capacity of ∼2900 mAh g−1 (at 0.2 C) and excellent cycling stability for a prolonged 200 cycles. The electrode also demonstrates appealing rate capability. The remarkable performance of nanostructured Si anode indicates the potential of its application as electrode materials for high performance energy storage.

► Ni-Si core-shell cylinders array with inner space has been fabricated by chemical etching.
► The discharge capacity was ∼2900 mAh g−1 and maintained well for 200 cycles.
► The abundant space between adjacent cylinders alleviated the inner strain during discharge.