Li-ion battery performance is dependent on ionic and electronic transport, in turn dependent on electrode microstructure. Changes in microstructure during cell formation and cycling are poorly understood. In this work, the changes in effective ionic conductivity and diffusivity are quantified in terms of MacMullin number, a dimensionless ionic resistance that is related to tortuosity. Using an AC impedance technique, namely the blocking electrolyte method, the ionic resistance of electrode films at varying extents of cycling was determined. Variations in electronic resistivity were quantified by micro-scale measurements using a previously developed micro-four-line probe. Cycling effects on the ionic and electronic resistivity were investigated for a graphite anode and multiple cathode chemistries including LiCoO₂ (LCO), LiNi_xCo_yMn_zO₂ (NCM), and LiFePO₄ (LFP). Clear evidence of changes in ionic and electronic resistivity were observed during cell formation and cycling. The magnitude of the changes depended on the chemistry of the electrodes and cycling conditions. The results indicate that, under normal cycling conditions, electronic resistivity increases while ionic resistivity is relatively stable and in some cases decreases, the latter being unexpected. However, under accelerated (high-temperature) cycling conditions, both electronic resistivity and ionic resistance were observed to increase.

锂离子电池的性能取决于离子和电子的传输，进而取决于电极的微结构。人们对细胞形成和循环过程中微观结构的变化知之甚少。在这项工作中，有效离子电导率和扩散率的变化通过MacMullin数来量化，MacMullin数是与曲折度相关的无量纲离子电阻。使用交流阻抗技术，即阻挡电解质法，确定了不同循环程度下电极膜的离子电阻。使用先前开发的微型四线探针通过微型测量来量化电阻率的变化。研究了石墨阳极和包括LiCoO ₂在内的多种阴极化学物质对离子和电子电阻率的循环效应（LCO），LiNi _x Co _y Mn _z O ₂（NCM）和LiFePO ₄（LFP）。在细胞形成和循环过程中观察到明显的离子和电子电阻率变化证据。变化的幅度取决于电极的化学性质和循环条件。结果表明，在正常循环条件下，电子电阻率增加，而离子电阻率相对稳定，在某些情况下降低，这是出乎意料的。但是，在加速（高温）循环条件下，观察到电子电阻率和离子电阻均增加。