Investigation of the chemo-mechanical coupling in lithiation/delithiation of amorphous Si through simulations of Si thin films and Si nanospheres

JOURNAL OF POWER SOURCES

卷:326

Article

Wang, Miao¹  Xiao, Xinran¹ 

[1] Michigan State Univ, Mech Engn, 2727 Alliance Dr, Lansing, MI 48910 USA

关键词: Chemo-mechanical coupling;    Lithiation and delithiation;    Asymmetric rate performance;    Finite element analysis;    Amorphous silicon thin films and nanospheres;   

DOI  :  10.1016/j.jpowsour.2016.07.011

来源: Elsevier

【 摘 要 】

A strong asymmetric rate behavior between lithiation and delithiation has been observed in amorphous Si (a-Si) anode in the form of thin films, but not in other geometries, such as Si nanospheres. This work investigated the rate behavior of the two geometries through numerical simulations. The results reveal that the rate behavior is affected by the geometry and the constraint of the electrode, the chemo-mechanical coupling, and the prior process. A substrate-constrained film has a relatively low surface/volume ratio and a constant surface area. Its lithiation has a great tendency to be hindered by surface limitation. The chemo-mechanical coupling also plays an important role. The stress profiles differ in the two geometries but both affect the lithiation process more than the delithiation process. The overall delithiation capacity is affected very little by the chemo-mechanical coupling. In cyclic loading, the delithiation capacity is reduced at the same rate as the lithiation capacity because of the low initial state of charge in the electrode. The asymmetric rate behavior was absent under cyclic loading. On the other hand, a slow charging process resulted in a better retained delithiation capacity and an asymmetric rate behavior at higher rates. (C) 2016 Elsevier B.V. All rights reserved.

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