In situ study on the charge/discharge of nanocrystalline Li2C2 as a new cathode material

摘要

The real-time charge and discharge processes of a single phase nanocrystalline Li2C2 alloy were directly observed by in situ transmission electron microscopy. Upon lithiation, nanocrystalline Li2C2 exhibits obvious volume expansion and morphology change, and an amorphous structure is generated from the nanocrystalline matrix. The change of structure affects the cycling stability of nanocrystalline Li2C2 as a cathode material. To reduce the effect of the structural change, the degree of delithiation was optimized by controlling the charge/discharge voltage range in the electrochemical tests. A high initial specific capacity of 352 mA h g(-1) was obtained for nanocrystalline Li2C2, and a discharge capacity of 171 mA h g(-1) was maintained after 50 cycles. The present work proposed a new alloy-type cathode material of nanocrystalline Li2C2 for lithium ion batteries with promising electrochemical performance.