Determining the chemical diffusion in active materials is crucial to the modeling and simulation of the chemo-mechanical interaction during electrochemical cycling of lithium-ion batteries, in which the diffusion coefficient of lithium plays an important role in describing the migration of lithium. Among the existing electrochemical measurement techniques, potentiostatic intermittent titration technique (PITT) is relatively reliable in determining diffusion coefficient in an electrochemical system since this technique relies only on the electrode dimension, i.e. the electrode thickness or the particle radius. In this work, a two-way coupling chemo-mechanical model is established to investigate the electrode transient current under PITT operation by incorporating the contribution of mechanical energy (hydrostatic stress) in chemical potential. The electrode transient current with the contribution of hydrostatic stress is compared to the counterpart with classical Fick diffusion law. Two key factors controlling the stress-diffusion coupling in the analysis of the electrode transient current under PITT operation are investigated, i.e. partial molar volume and elastic modulus of spherical particle. A ratio of the “intrinsic” diffusion coefficient to the nominal diffusion coefficient is defined to quantitively analyze the effects of the stress-diffusion coupling on the diffusion coefficient determined from PITT operation. The numerical results reveal that a large partial molar volume and/or a large elastic modulus will result in significant deviation of the diffusion coefficient by using PITT technique without considering the stress-diffusion coupling effects.

确定活性材料中的化学扩散对于锂离子电池电化学循环过程中化学-机械相互作用的建模和模拟至关重要，其中锂的扩散系数在描述锂的迁移中起着重要作用。在现有的电化学测量技术中，恒电位间歇滴定技术（PITT）在确定电化学系统中的扩散系数方面相对可靠，因为该技术仅依赖于电极尺寸，即电极厚度或颗粒半径。在这项工作中，通过结合机械能（静水应力）对化学势的贡献，建立了一个双向耦合化学机械模型来研究 PITT 操作下的电极瞬态电流。将具有静水应力贡献的电极瞬态电流与经典菲克扩散定律的对应物进行了比较。研究了PITT操作下电极瞬态电流分析中控制应力-扩散耦合的两个关键因素，即球形颗粒的偏摩尔体积和弹性模量。定义“固有”扩散系数与标称扩散系数的比率，以定量分析应力-扩散耦合对由 PITT 操作确定的扩散系数的影响。数值结果表明，在不考虑应力-扩散耦合效应的情况下，采用PITT技术，较大的偏摩尔体积和/或较大的弹性模量将导致扩散系数的显着偏差。