Meng Qingping, Wu Lijun, Welch David O, Tang Ming, Zhu Yimei
Brookhaven National Laboratory, Upton, New York, 11973, USA.
Department of Materials Science & Nanoengineering, Rice University, Houston, USA.
Sci Rep. 2018 Mar 21;8(1):4936. doi: 10.1038/s41598-018-23320-7.
The stress-free strain originated from local chemical composition and phase transformation can significantly alter the microstructures of materials; and then affect their properties. In this paper, we developed an analytical method to calculate stress-strain field due to the non-uniform stress-free strain in a spherically symmetrical particle. Applying the method to a lithium ion (Li-ion) battery electrode, the evolution of Li-ion concentration and strain field during the lithiation process is studied. Our studies reveal that the maximum strain in the electrode generally occurs on surface of sample, and is mainly dependent on the difference of Li-ion concentration of surface and of center in sample. Decreasing the difference of Li-ion concentration can efficiently decrease the maximum strain so that cracks of electrodes can been prevented. Our analytical results provide a useful guidance for practical applications of energy storage materials.
由局部化学成分和相变产生的无应力应变可显著改变材料的微观结构，进而影响其性能。本文中，我们开发了一种分析方法来计算球对称颗粒中由于非均匀无应力应变产生的应力应变场。将该方法应用于锂离子电池电极，研究了锂化过程中锂离子浓度和应变场的演变。我们的研究表明，电极中的最大应变通常出现在样品表面，并且主要取决于样品表面和中心锂离子浓度的差异。减小锂离子浓度差异可有效降低最大应变，从而防止电极开裂。我们的分析结果为储能材料的实际应用提供了有用的指导。
