Structural Damage of Few-Layer Silicene in Vertical and Parallel Lithiations

MZ Yao and LQ Ai and YS Zhou and JH Ma and M Chen, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 166, A3394-A3400 (2019).

DOI: 10.1149/2.1051914jes

Few-layer silicene is a promising anode material for lithium (Li) ion batteries. In this work, the structural damage of few-layer silicene in vertical and parallel lithiation processes are investigated using reactive force field molecular dynamics simulations. Simulation results showed that within a certain degree of lithiation, the layered structure of few-layer silicene is severely damaged during parallel lithiation but can be preserved during vertical lithiation. During lithiation, Li atom has two typical reacting paths, namely, damaging and migrating paths. In the damaging path, Li atoms form Li-Si (Silicon) bonds with Si atoms at the surface and participate in structural damage. In the migrating path, Li atoms migrate into the few-layer silicene and form Li-Si bonds with the inner Si atoms. The migrating path has significantly lower energy barrier height than the damaging path in vertical direction, whereas their energy barriers have similar height in the parallel direction. Li atoms prefer the damaging path during parallel lithiation and the migrating path during vertical lithiation. As the edge area of few-layer silicene is limited, the probability of parallel lithiation is relatively low. Reducing the height and enlarging the width and length of few-layer silicene pieces might improve the cyclability of silicene anodes. (C) 2019 The Electrochemical Society.

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