A thermodynamically consistent gradient theory for diffusion–reaction–deformation in solids: Application to conversion-type electrodes
A thermodynamically consistent gradient theory for diffusion–reaction–deformation in solids: Application to conversion-type electrodes
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DOI：
10.1016/j.jmps.2021.104368
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发表时间：
2021-06
影响因子：
5.3
通讯作者：
Arman Afshar;Claudio V. Di Leo
中科院分区：
文献类型：
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作者：
Arman Afshar;Claudio V. Di Leo
我们发展了一个热力学一致的相场有限应变理论来解决固体力学中的问题，这些问题包括物种向宿主材料的传输、物种与宿主的尖锐界面反应、机械变形和应力。该理论区分了扩散限制动力学和反应限制动力学，解决了在任何一种情况下都可以形成尖锐反应前沿的方式。相场公式还有一个额外的好处，那就是能够应用润湿(表面能)边界条件，这些条件对于再现实验上相关的反应前沿形态至关重要。该理论与影响机械变形和随后的应力产生的扩散和反应现象完全耦合，反之，这些现象与机械应力耦合。通过对这些现象的连续处理，我们得到了热力学上一致的扩散和反应驱动力。重要的是，由此得到的公式使驱动这些热力学作用力的材料属性的性质变得精确，进而使其易于专门应用和校准。虽然该框架非常通用，但我们将其应用于利用三维有限元实现对转换电极进行能量存储的建模。我们演示了理论可以以直接的方式被专门化和校准的方式。对FeS2晶体与锂离子和钠离子的化学反应进行了模拟，并与同一体系的实验观测结果进行了比较。我们的模拟结果与实验观测结果有很好的定性一致性，并阐明了力学在决定尖锐反应界面的形态和随后可能导致这些材料力学劣化的应力产生方面所起的关键作用。除了这种应用，理论框架应该在一些相关的工程问题上有用，在这些问题中发生扩散和尖锐的界面反应。
We develop a thermodynamically consistent phase-field finite strain theory for problems in solids mechanics that couple transport of species into a host material, sharp interface reactions of the species with the host, mechanical deformation and stress. The theory distinguishes between diffusion-limited and reaction-limited kinetics, resolving the manner in which a sharp reaction front can be developed in either case. The phase field formulation has the added benefit of enabling the application of wetting (surface energy) boundary conditions which are critical in reproducing experimentally relevant reaction front morphologies. The theory is fully coupled with diffusion and reaction phenomena impacting mechanical deformation and subsequent stress generation, and conversely these phenomena are coupled to mechanical stress. We derive thermodynamically consistent driving forces for diffusion and reaction through a continuum treatment of these phenomena. Importantly, the resulting formulation makes precise the nature of the material properties driving these thermodynamic forces and in turn makes it amenable to being specialized and calibrated for application. While the framework is quite general, we apply it to modeling conversion electrodes for energy storage using a three-dimensional finite element implementation. We demonstrate the manner in which the theory can be specialized and calibrated in straightforward fashion. Simulations are performed of chemical reactions of FeS 2 crystals with lithium and sodium ions, both of which proceed through the formation and propagation of a sharp interface, and are compared to experimental observations of the same system. Our simulations show good qualitative agreement with experimental observations, and elucidate the critical role mechanics plays in determining the morphology of the sharp reaction interface and subsequent stress generation which can lead to mechanical deterioration of these materials. Beyond this application, the theoretical framework should serve useful in a number of engineering problems of relevance in which diffusion and sharp interface reactions occur.