期刊
ACS NANO
卷 9, 期 2, 页码 1985-1994出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn507003z
关键词
Li-ion battery; nanotube; silicon anode; capacity; plastic strain
类别
资金
- U.S. Department of Energy, Office of Science, Basic Energy Sciences [DE-FG02-07ER46471]
- State Key Project of Fundamental Research for Nanoscience and Nanotechnology of China [2011CB933700]
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 carbonsiliconcarbon (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 similar to 2200 mAh g(1) (similar to 750 mAh cm(3)), which significantly exceeds that of a commercial graphite anode, and a nearly constant Coulombic efficiency of similar to 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.
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