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中国物理学会期刊

表面效应对纳米线电极屈曲失稳的影响

CSTR: 32037.14.aps.71.20211864

Surface effects on buckling of nanowire electrode

CSTR: 32037.14.aps.71.20211864
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  • 纳米线电极在充/放电过程中引起电极的屈曲失稳行为可能会对结构造成力学损伤. 本文针对纳米线电极结构, 建立了包含锂扩散、应力、浓度影响弹性模量的多场耦合理论模型. 基于构建的模型, 研究了表面效应对纳米线电极屈曲失稳的影响. 结果表明表面效应能够提高纳米线电极的抗屈曲性, 延迟纳米线电极的临界屈曲时间. 同时, 表面效应的影响表现出半径尺寸和长细比的依赖性, 即随着电极半径尺寸的增大而减小, 而随着电极长细比的增大而增大. 此外, 模型还显示, 在有表面效应的条件下, 相对于弹性硬化属性的纳米线电极, 具有弹性软化属性的电极因为具有更好的抗失稳性而更适宜作为电极材料. 研究结果为纳米线电极的力学可靠性设计提供了一定的帮助.

     

    Nanowire-based electrodes have attracted much attention due to their high surface energy, short distance for lithium insertion, and the ability to accommodate the enormous strain. However, the buckling behavior may occur during lithiation for such wire-like electrodes, which would lead the battery performance to deteriorate. Therefore, it is vital to quantitatively understand the mechanism about the bucking behavior of the nanowire-based electrodes. Although the buckling behavior of wire-like electrode has been extensively studied in the past few decades, the influence of surface effect on it has not yet been thoroughly explored. For this purpose, a theoretical model of surface effects on buckling of nanowire electrode is presented by taking into account the lithium diffusion, stress, and concentration-dependent elastic properties. Based on the established model, the effects of the residual surface tension and elastic hardening/softening coefficients on buckling are investigated. The results show that surface effects can improve the mechanical reliability, thus delaying the critical buckling time of nanowire electrode. In addition, it is indicated that the surface effects depend on the radius size and slenderness ratio of the nanowire electrode, specifically, the smaller the radius size and the larger the slenderness ratio, the greater the influence of the surface effect is. Furthermore, compared with elastic hardening, with the participation of surface effects, the larger the elastic softening coefficient, the longer it takes for the nanowire electrode to reach the buckled state, and the better the stability of the electrode is. The novelty of this work is that the proposed models highlight the importance of surface effects on buckling of nanowire electrode. These findings provide a prospective insight into the designing of higher structural reliability of electrode.

     

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