Silicon Surface Structure and Bonding

High-resolution XPS is often used to characterize the local structure and bonding environments and can be used to better understand the nature of the interface between the SEI and Si surface. The 

XPS spectrum of the as-grown SiNWs is shown in Fig. 1.26. It is characterized by the Si-Si peak at 99 eV and the Si-0 peak at about 103 eV due to Si02. The presence of the native oxide is due to the SiNWs being exposed to air after the growth, which results in the 

Due to the high surface-to-volume ratio of the NWs, it appears that surface bonding plays a large role in the bonding of the Si compared to Li alloy formation in the bulk of the NW. 

For reliable and efficient use of Si anodes in Li-ion batteries, it is vitally important to form a passivating SEl of limited thickness on the surface of the anode structures. However, the large volume changes inherent to the cycling of Si can result in unstable SEl formation. This is because the SEl formed on the surface during lithiation can rupture during delithiation (due to contraction of the Si], resulting 

DuetothethinandpassivatingSEIformedonthesenanostructures, stable cycling of double-walled Si nanotube electrodes was possible for thousands of cycles. This is illustrated in Fig. 1.28, which shows the specific capacity and the galvanostatic voltage curves of a double-walled Si nanotube electrode tested in a half cell at a rate of 12C over 

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