Mechanical Properties of Two-Dimensional Materials (Graphene, Silicene and MoS 2 Monolayer) Upon Lithiation
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https://doi.org/10.1007/s11664-020-08333-1 2020 The Minerals, Metals & Materials Society
Mechanical Properties of Two-Dimensional Materials (Graphene, Silicene and MoS2 Monolayer) Upon Lithiation LEI YE,1 SHIYUN WU,2 and ZHIGUO WANG1,3 1.—University of Electronic Science and Technology of China, Chengdu 610054, People’s Republic of China. 2.—School of Intelligent Manufacturing, Sichuan University of Arts and Science, Dazhou 635000, People’s Republic of China. 3.—e-mail: [email protected]
The mechanical stability of electrode materials in lithium-ion batteries (LIBs) is critical for their safe usage. Two-dimensional (2D) materials have been widely studied to be used as electrode materials for LIBs. In this paper, the mechanical properties of several typical 2D materials, including graphene, silicene and MoS2 monolayer upon lithium intercalation were studied, based on the density functional theory calculations with the model developed by Topsakal and Ciraci (Appl Phys Lett 96:091912, 2010). It was found that the in-plane stiffness of 2D materials decreases with increases of lithium concentration. In-plane stiffness decreased about 9.8% at lithium concentration of ˚ 2 for sil˚ 2 for graphene and 6.0% at a concentration of 0.153 Li/A 0.184 Li/A icene. The evolution of in-plane stiffness of MoS2 monolayer as a function of lithium concentration and electron-doping concentration were compared. The in-plane stiffness of MoS2 monolayer decreased with increases of Li and electron concentration, which revealed that the electron doping effect is the mechanism causing the decrease of the mechanical stability of electrode materials upon lithiation. Key words: Mechanical properties, Li intercalation, electron doping, two-dimensional materials
INTRODUCTION With the ever-increasing demand for high-power, large-capacity and long-life lithium-ion batteries (LIBs), researchers are seeking a new generation of electrode materials. Low-dimensional materials are the focus of recent research due to their lightness,anti-deformation characteristics and large capacity.1–9 In addition to graphene, other twodimensional (2D) materials, such as silicene and MoS2, have been widely studied as electrode materials for LIBs. Graphene has become one of the most popular 2D materials in recent years due to its excellent physicochemical properties, such as high carrier mobility, high mechanical strength and light weight.1–5,10–16 Silicene is a new type of 2D material
(Received January 20, 2020; accepted July 13, 2020)
which has many unique properties, such as excellent electrical conductivity and smaller volume expansion during lithium insertion than bulk crystalline Si, thus the usage of silicene as a promising LIBs anode material has been investigated.6–8,13,17–25 MoS2 monolayer shows promise as an excellent LIB electrode material owing to its large energy storage capacity.9,26–37 The atomic configuration and mechanical stability of Li-intercalated electrode materials are important qualities for evaluating the electrochemical performance of LIB
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