文摘
Annealing treatment of as-deposited β-Sn film on Cu resulted in the development of ‘composite’ film comprised of Sn-Cu intermetallic phases (Cu3Sn and Cu6Sn5) surrounding ‘percolating’ network of β-Sn, all underneath a thin continuous β-Sn layer. Such phase assemblage and microstructure-type resulted in significantly improved mechanical integrity upon lithiation/delithiation; and accordingly very stable Li-capacity retention with continued electrochemical cycling. In-situ monitoring of the stress developments during lithiation/delithiation indicated that the presence of intermetallic ‘buffer’ phase(s) results in ~ 3 times lower stress magnitudes compared to ‘pure’ Sn upon ‘full’ lithiation, along with absence of signature for mechanical degradation in the stress-time profiles.