Microstructure evolution of novel Sn islands prepared by electrodeposition as anode materials for lithium rechargeable batteries

Here, we describe the striking irreversible volume expansion of micron-sized Sn anodes for lithium rechargeable batteries during cycling with brand-new Sn islands that are prepared by electrodeposition on a Cu substrate. Exceptional changes in the internal as well as external microstructure of the electrodeposited Sn islands are demonstrated by ex situ morphological analyses. The cross sectional micrographs of the Sn islands prove the widespread formation of nano-voids within individual Sn islands after initial Li dealloying followed by their enrichment during the subsequent cycles. These widespread voids and the following dead volume formed inside the Sn islands induce irreversible volume expansion in the micron-sized Sn anodes, thereby deteriorating the cycling performance of the Sn anodes.