It is well-kown that LiSi alloy forms by electrochemical lithiation of Si substrate. Since the high performance of Li insertion amount into Si is theoretically predicted, LiSi alloy formation has attracted a great attention not only for industrial applications such as Li-ion and Li-airbatteries but also for fundamental electrochemistry area. X-ray photoelectron spectroscopy (XPS) method was often used for electronic state analysis of LiSi alloy. However, information from XP spectrum is limited about inner shell electron and then, electronic state of LiSi alloy has not been made clear yet. On the other hand, soft X-ray emission spectroscopy (SXES) provides us the information about valence band electron. In this study, we electrochemically prepared the samples with different amounts of Li insertion and investigated the geometric and electronic structures of electrochemically lithiated Si substrate by SXES combining with scanning electron microscopy (SEM) and X-ray diffraction (XRD). We found that two kind phases were formed on the Si substrate; one is the Li15Si4 alloy phase and the other is the mixed phase of crystalline Si (c-Si) and a little amount of Li15Si4 alloy.

Electrochemical lithiation process into Si substrate

251st National Meeting (2016)

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