TY - DATA T1 - Mechanically and Chemically Robust Sandwich-Structured C@Si@C Nanotube Array Li-Ion Battery Anodes PY - 2015/02/24 AU - Jinyun Liu AU - Nan Li AU - Matthew D. Goodman AU - Hui Gang Zhang AU - Eric S. Epstein AU - Bo Huang AU - Zeng Pan AU - Jinwoo Kim AU - Jun Hee Choi AU - Xingjiu Huang AU - Jinhuai Liu AU - K. Jimmy Hsia AU - Shen J. Dillon AU - Paul V. Braun UR - https://acs.figshare.com/articles/journal_contribution/Mechanically_and_Chemically_Robust_Sandwich_Structured_C_Si_C_Nanotube_Array_Li_Ion_Battery_Anodes/2193598 DO - 10.1021/nn507003z.s001 L4 - https://ndownloader.figshare.com/files/3827923 KW - chemical stability issues KW - plastic strain KW - energy densities KW - Coulombic efficiency KW - capacity decay KW - structure stability KW - battery electrodes KW - Si anodes KW - volume changes KW - graphite anode KW - anode candidate KW - Si nanotubes KW - Ni foam KW - SEM KW - SEI KW - cathode systems KW - 60 cycles KW - carbon coatings N2 - Stability and high energy densities are essential qualities for emerging battery electrodes. Because of its high specific capacity, silicon has been considered a promising anode candidate. However, the several-fold volume changes during lithiation and delithiation leads to fractures and continuous formation of an unstable solid-electrolyte interphase (SEI) layer, resulting in rapid capacity decay. Here, we present a carbon–silicon–carbon (C@Si@C) nanotube sandwich structure that addresses the mechanical and chemical stability issues commonly associated with Si anodes. The C@Si@C nanotube array exhibits a capacity of ∼2200 mAh g–1 (∼750 mAh cm–3), which significantly exceeds that of a commercial graphite anode, and a nearly constant Coulombic efficiency of ∼98% over 60 cycles. In addition, the C@Si@C nanotube array gives much better capacity and structure stability compared to the Si nanotubes without carbon coatings, the ZnO@C@Si@C nanorods, a Si thin film on Ni foam, and C@Si and Si@C nanotubes. In situ SEM during cycling shows that the tubes expand both inward and outward upon lithiation, as well as elongate, and then revert back to their initial size and shape after delithiation, suggesting stability during volume changes. The mechanical modeling indicates the overall plastic strain in a nanotube is much less than in a nanorod, which may significantly reduce low-cycle fatigue. The sandwich-structured nanotube design is quite general, and may serve as a guide for many emerging anode and cathode systems. ER -