10.1021/nn507003z.s001
Jinyun Liu
Jinyun
Liu
Nan Li
Nan
Li
Matthew D. Goodman
Matthew D.
Goodman
Hui Gang Zhang
Hui Gang
Zhang
Eric S. Epstein
Eric S.
Epstein
Bo Huang
Bo
Huang
Zeng Pan
Zeng
Pan
Jinwoo Kim
Jinwoo
Kim
Jun Hee Choi
Jun Hee
Choi
Xingjiu Huang
Xingjiu
Huang
Jinhuai Liu
Jinhuai
Liu
K. Jimmy Hsia
K. Jimmy
Hsia
Shen J. Dillon
Shen J.
Dillon
Paul V. Braun
Paul V.
Braun
Mechanically and Chemically Robust Sandwich-Structured C@Si@C Nanotube Array Li-Ion Battery Anodes
American Chemical Society
2015
chemical stability issues
plastic strain
energy densities
Coulombic efficiency
capacity decay
structure stability
battery electrodes
Si anodes
volume changes
graphite anode
anode candidate
Si nanotubes
Ni foam
SEM
SEI
cathode systems
60 cycles
carbon coatings
2015-02-24 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Mechanically_and_Chemically_Robust_Sandwich_Structured_C_Si_C_Nanotube_Array_Li_Ion_Battery_Anodes/2193598
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<sup>–1</sup> (∼750 mAh cm<sup>–3</sup>), 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. <i>In situ</i> 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.