The persistence of phase-separation in LiFePO4 with two-dimensional Li+ transport: The Cahn-Hilliard-reaction equation and the role of defects

被引：33

作者：

Dargaville, S. ^{[1
]}

Farrell, T. W. ^{[1
]}

机构：

[1] Queensland Univ Technol, Brisbane, Qld 4001, Australia

来源：

ELECTROCHIMICA ACTA | 2013年 / 94卷

关键词：

Cahn-Hilliard-reaction; LiFePO4; Defects; Phase-separation; Phase-field; TRANSITION PATHWAYS; BATTERY MATERIALS; COHERENCY STRAIN; DISCHARGE MODEL; PARTICLE-SIZE; ELECTRODES; DIFFUSION; CONDUCTIVITY; MECHANISMS; DEPENDENCE;

D O I：

10.1016/j.electacta.2013.01.082

中图分类号：

O646 [电化学、电解、磁化学];

学科分类号：

081704 ;

摘要：

We examine the solution of the two-dimensional Cahn-Hilliard-reaction (CHR) equation in the xy plane as a model of Li+ intercalation into LiFePO4 material. We validate our numerical solution against the solution of the depth-averaged equation, which has been used to model intercalation in the limit of highly orthotropic diffusivity and gradient penalty tensors. We then examine the phase-change behaviour in the full CHR system as these parameters become more isotropic, and find that as the Li+ diffusivity is increased in the x direction, phase separation persists at high currents, even in small crystals with isotropic coherency strain included. The resulting voltage curves decrease monotonically, which has previously been considered a hallmark of crystals that fill homogeneously. (C) 2013 Elsevier Ltd. All rights reserved.

引用

页码：143 / 158

页数：16

共 44 条

[21] Phase field theory of heterogeneous crystal nucleation [J].