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Lithium-Ion Battery

1. ab initio Study of Anisotropic Mechanical Properties of LiCoO2 during Lithium Intercalation and Deintercalation Process

LiCoO2 DFT VASP

The mechanical properties of LixCoO2 under various Li concentrations and the associated anisotropy have been systematically studied using the first principles method. During lithium intercalation process, the Young’s modulus, bulk modulus, shear modulus and the ultimate strength increase with increasing lithium concentration. Strong anisotropy of mechanical properties between a-axis and c-axis in LixCoO2 is identified at low lithium concentrations, and the anisotropy decreases with increasing lithium concentrations. The observed lithium concentration dependence and anisotropy is explained by analyzing the charge transfer using Bader charge analysis. Bond strength is also studied by investigating partial density of states and charge density difference. With the decrease of Li concentration, the charge depletion in the bonding regions increases, indicating a weaker Co-O bond strength. Additionally, the Young’s modulus, bulk modulus, shear modulus and toughness are obtained by simulated ab initio tensile tests. From the simulated stress-strain curves, LixCoO2 shows the highest toughness, which is in contraction with Pugh criterion prediction, which is based on elastic properties only.

Publications:

1. Linmin Wu, Jing Zhang, Ab initio Study of Anisotropic Mechanical Properties of LiCoO2 during Lithium Intercalation and Deintercalation Process, Journal of Applied Physics , 118, 225101, 2015

2. Linmin Wu, Weng-Hoh Lee, Jing Zhang, First Principles Study on the Electrochemical, Thermal and Mechanical Properties of LiCoO2 for Thin Film Rechargeable Battery. Materials Today: Proceedings, 1(1): p. 82-93, 2014

2. Microstructure-Based Diffusion Induced Stress in Lithium-Ion Battery

FIB SEM LIB stress
Synchrotron microCT NMC half cell
phase field FEM LIB stress

In this study, the stress generation of LiCoO2 and NMC with (1) realistic 3D microstructures and/or (2) generated through phase field simulation has been studied systematically. The realistic microstrucutres are generated through FIB-SEM or synchrotron X-ray tomography technique. The stresses due to (1) lithium ion diffusion, (2) phase transformation, and (3)microstrucure characteristics are studied.

Publications:

1.Linmin Wu, Xianghui Xiao, Youhai Wen, Jing Zhang, Three-Dimensional Finite Element Study on Stress Generation in Synchrotron X-Ray Tomography Reconstructed Nickel-Manganese-Cobalt Based Half Cell, Journal of Power Sources, Vol. 336, pp. 8-18, 2016

2.Linmin Wu, Youhai Wen, Jing Zhang, Three-Dimensional Finite Element Study on Li Diffusion Induced Stress in FIB-SEM Reconstructed LiCoO2 Half Cell, Electrochimica Acta (doi: 10.1016/j.electacta.2016.11.042)

3.Linmin Wu, Yi Zhang, Yeon-Gil Jung, Jing Zhang, Three-dimensional phase field based finite element study on lithium intercalation-induced stress in polycrystalline LiCoO2, Journal of Power Sources , Vol. 299, pp. 57-65, 2015