The effect of thin film morphology on the electrochemical performance of Cu-Sn anode for lithium rechargeable batteries

We investigate the anode performance of non ordered and ordered nanostructured Cu-Sn thin films deposited via electron beam deposition technique. The ordered nanostructured Cu-Sn thin film having nano-porosities was fabricated using an oblique (co)deposition technique. Our results showed that the nano structured Cu-Sn thin film containing Cu-Sn nanorods had higher initial anodic capacity (790 mA h g^-) than that of the non ordered thin film (330 mA h g^-). But the capacity of the ordered nanostructured Cu-Sn thin film diminished after the first cycle and a steady state capacity value around 300 mA h g^- is sustainable in following up to 80th cycle, which is attributed to the composition and morphology of the thin film. The presence of copper containing Sn nanorods leading to form nano-porosities as interstitial spaces among them, enhanced lithium ions movement within thin film and increased the thin film tolerance against the stress generated because of the drastic volume change occurred during lithiation-delithiation processes; hence, homogenously distributed porosities increased the cycle life of the thin film.