Abstract
Huge volume expansion of Sn-based anode during Li-insertion leads to instability of the electrodes and degrades the electrochemical performances and thus prohibited their practical applications. Herein we propose a new "digging holes" approach to develop a three dimensional CuSn electrode, in which the active Sn adhere to conductive Cu framework. The designed porous structures significantly contribute to the suppression of volume changes and promote the electrolyte permeation, whereas the Cu framework improves the electrode conductivity. When tested as an anode in the Li-ion battery, the porous CuSn displays a superb cycle stability (673 mA h/g after 50 cycles at 334 mA/g), and fast Li+ storage properties (e.g. 566 mA h/g at 1670 mA/g). The perfect structural stability is further verified through building a prototype nanobattery using in situ TEM technique; the maintained pores and the lithiated Li2CuSn products during discharging are observed in real time, thus uncovering the reasons behind the excellent performances. In addition, Li+ ions are found to preferably penetrate into the CuSn alloy through its facets on (42 (2) over bar) planes due to the perfect lattice match. The designed nanoporous CuSn alloy is envisaged to effectively serve as a potential anode for stable and fast Li-ions storage.