The importance of electrochemical stress has been widely recognized because it determines the lifetime of lithium-ion (Li⁺) batteries. Herein, we propose an in-situ method to visually measure the electrochemical stress fields associated with strain and Li⁺ concentration along the diffusion path. Three important links are established successively; namely, an electrochemical stress model, visual observation, and in-situ collaborative measurements of core mechano-electrochemical parameters. The strain field and Li⁺ concentration distribution in a graphite electrode are measured in situ using a dual optical system. The electrochemical stress field considering Li⁺ concentration, strain and Li⁺-dependent stiffening is obtained. The spatiotemporal evolution of the experimental parameters is evaluated. The experimental results demonstrate that the electrode experiences compressive stress and tensile strain. The strain and electrochemical stress exhibit gradient distributions along the Li⁺ diffusion path and increase with the electrochemical process. Furthermore, the mechano-electrochemical interrelation of tensile strain, compressive stress and Li⁺ concentration is considered. It is demonstrated that compressive stress (tensile strain) evolves linearly (nonlinearly) with Li⁺ concentration. Mechanical constraint-induced stress (i.e., strain) and Li⁺ concentration-induced stress show opposing positive and negative states, making them competitive contributions to electrochemical stress. This study increases understanding of the mechano-electrochemical interrelation in electrodes, which will help to improve electrode performance.

电化学应力的重要性已得到广泛认可，因为它决定了锂离子 (Li ⁺ ) 电池的寿命。在此，我们提出了一种原位方法来直观地测量沿扩散路径与应变和 Li ⁺浓度相关的电化学应力场。三个重要环节相继建立；即电化学应力模型、目视观察和核心机械电化学参数的原位协同测量。使用双光学系统原位测量石墨电极中的应变场和 Li ⁺浓度分布。考虑Li ⁺浓度、应变和Li ⁺的电化学应力场获得依赖的刚度。评估实验参数的时空演变。实验结果表明，电极经受压应力和拉伸应变。应变和电化学应力沿 Li ⁺扩散路径呈现梯度分布，并随着电化学过程而增加。此外，还考虑了拉伸应变、压缩应力和 Li ⁺浓度的机械-电化学相互关系。结果表明，压缩应力（拉伸应变）随 Li ⁺浓度线性（非线性）演变。机械约束引起的应力（即应变）和 Li ⁺浓度引起的应力显示出相反的正负状态，使它们对电化学应力有竞争性的贡献。这项研究增加了对电极中机械-电化学相互关系的理解，这将有助于提高电极性能。