Mechanochemistry of advanced anode designs in Li-ion batteries

这一建议是对基于连续介质物理基本原理的定量建模提高锂离子电池(LIBS)性能的贡献。锂离子电池是重要的储能设备。它们在各种技术应用中都是必需的，例如便携式电子产品或为车辆提供动力。在充电和放电过程中，锂在负极材料中的加入和去除必须被视为一种化学反应，伴随着体积的显著增加，导致巨大的机械应力和应变的积累。这些都会对LIBS的主要可充电性产生影响，因为它们最终会阻止反应。此外，它们还可能导致电池材料的物理损坏。当然，为了防止这种情况的发生，已经采取了经验措施，一种是基于选择球状、棒状、蜂窝状等不同设计的带电硅结构，另一种是转向比硅更脆的其他宿主材料。然而，就定量建模而言，对机械力-化学耦合过程的彻底的基于物理的理解仍处于初级阶段。当然，已经有人尝试对这种现象进行建模。然而，公平地说，机械和热化学方面的结合是在相当现象学的基础上完成的。简而言之：相应的理论并不是用热力学基本原理建立在坚实的基础上的。这就是我们提出这项建议的原因。首先，我们将建立一个一致的机械力化学理论。其次，这一理论将被解析和数值利用，同时确定方程中的每一项为什么和从哪里产生，以及它如何对观察到的不同结构设计的各种阳极材料的微观形态变化做出贡献。第三，我们将比较我们的模型并将其与真实的定制实验联系起来，以便提高其适用性，而不是通过调整系数，而是始终基于基本原理。最终我们将拥有一个可靠的工具，可以在未来的LIBS的设计过程中使用。两个研究小组在这些领域都有多年的经验，从理论和实验的角度来看都是相辅相成的。到目前为止，俄罗斯团队的重点是，第一，建立热力学上一致的奇异界面理论，第二，将它们应用于硅氧化的(定性)建模。首先，德国团队在锡铅和银铜共晶焊料的调幅分解的多组分扩散和相场建模方面具有专业知识，其次，在连续介质建模领域，具有强大的实验和工业基础的定量建模背景。

This proposal is a contribution toward improving the performance of Lithium-Ion Batteries (LIBs) by quantitative modeling based on fundamental principles of continuum physics. LIBs are important energy storage devices. They are required in various technological applications, such as portable electronics or for the powering of vehicles. The incorporation and removal of Li in the anode material during charging and discharging, which must be considered as a chemical reaction, is accompanied by a considerable increase in volume giving rise to a build-up of huge mechanical stresses and strains. These have an impact on the principal rechargeability of LIBs because they eventually block the reaction. Moreover, they might result in physical damage of the battery material. Of course, empirical measures have been taken in order to prevent this from happening, one based on choosing different designs of the to-be-charged silicon structure in terms of spheres, rods, honeycombs, etc., and the other consisting of turning to other host materials less brittle than Si. However, a thorough physically-based understanding of the mechano-chemically coupled process in terms of quantitative modeling is still at its infancy. Surely, there have been attempts at modeling the phenomenon. However, it is fair to say that joining the mechanical and thermochemical aspects has been accomplished on a rather phenomenological basis. In short: The corresponding theory was not built on solid ground by using fundamental thermodynamics principles. This is why we present this proposal. We shall, first, establish a consistent mechano-chemical theory. Second, this theory will be exploited analytically as well as numerically while being sure why and from where each term in the equations originates and how it contributes to the observed micromorphological changes in various anode materials of different structural design. Third, we shall compare and link our models to real custom-made experiments in order to improve its applicability not by adjusting coefficients but always by basing it on first principles. In the end we will possess a reliable tool to-be-used during the design process of future LIBs. Both research teams have many years of experience in these fields and complement each other both from the theoretical as well as from the experimental point-of-view. So far the Russian team has focused on, first, setting up thermodynamically consistent singular interface theories and, second, on applying them, for example, to the (qualitative) modeling of silicon oxidation. The German team contributes with expertise in, first, multi-component diffusion and phase-field modeling of the spinodal decomposition of eutectic tin-lead and silver copper solders, and, second, a strong experimentally as well as industrially based background to quantitative modeling in this field of continuum modeling.