材料科学
阳极
电解质
硅
扩散
离子
化学工程
电极
扩散阻挡层
晶体硅
图层(电子)
纳米技术
化学物理
物理化学
光电子学
热力学
物理
工程类
量子力学
化学
作者
Long Li,Chun Fang,Wenfei Wei,Lei Zhang,Ye Zhao,Gang He,Yunhui Huang
出处
期刊:Nano Energy
[Elsevier]
日期:2020-02-27
卷期号:72: 104651-104651
被引量:71
标识
DOI:10.1016/j.nanoen.2020.104651
摘要
The huge volume change of silicon anode during cycling results in unstable solid electrolyte interface (SEI), causing rapid performance degradation. Natural SEI layer has a heterogeneous structure, results in the inhomogeneous Li+ diffusion. The repeated destruction and regeneration of SEI aggravate the inhomogeneity of Li+ diffusion at the interface, leading to non-uniform alloy reaction in the Si bulk. In this work, the silicon surface is passivated by an ultrathin uniform chitosan layer with abundant lithiophilic groups. The capacity of chitosan-coated Si ([email protected]) could reach 1500 mAh g−1 at a current density of 1 A g−1, and the capacity retention remains 91% after 400 cycles. It is demonstrated that the oxygen and nitrogen atoms in chitosan are coordinated with Li+, providing uniformly distributed Li+ transfer sites, results in a homogeneous Li+ flux in the surface layer. Interestingly, a nano-scale ordered atomic arrangement is observed in the delithiated [email protected], which contributes to more stable and reversible lithiation/delithiation reaction of the [email protected] electrode. It is proposed that optimizing the reaction interface on the Si surface is able to alter the Li-ion diffusion kinetics and structure transition behavior of silicon, which can improve the structure reversibility and stability during cycling.
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