Ultrafast and reversible electrochemical lithiation of InAs nanowires observed by in-situ transmission electron microscopy

The electrochemical lithiation/delithiation processes of InAs nanowires (NWs) are studied by in-situ transmission electron microscopy. Our results indicate that InAs NWs have a fast lithiation speed of 275 nm/s and a high lithium ion (Li-ion) diffusion coefficient of 2.49 x 10(-8) cm(2)/s at room temperature. Upon lithiation, the Li-ion insertion firstly results in severe lattice distortions of InAs NWs, and the formation of Li3As and LixIn through the conversion and alloying processes take place on further lithiation. A small volume expansion of 157% is observed in full lithiation and is attributed to the naturally formed surface oxide layer. During the delithiation process, volume contraction and the dealloying of LixIn take place. Induced by the alloying and dealloying of LixIn, the dark and bright strips along the basal plane of InAs NWs appear and disappear alternately during the lithiation-delithiation cycling. Our results provide important insights into the lithiation/delithiation mechanism of III-V group nanomaterials and are envisaged to be helpful for designing lithium ion battery anode materials with fast lithiation speed, small volume expansion and reversible lithiation/delithiation processes. (C) 2015 Elsevier Ltd. All rights reserved.