The Effect of Mud Cracking on the Performance of Thick Li-Ion Electrodes

Electrode-level fracture, or mud cracking, occurs during the drying process of Li-ion electrodes and is known to be particularly prevalent in thick electrodes. Whilst these cracks are generally viewed as an obstruction to the production of thicker, more energy dense electrodes, cracks are similar in structure to directional pore channels which have been proposed as a means of improving ion transport to produce thicker electrodes more capable of performing at higher rates. However, existing literature has not thoroughly investigated the influence of cracking on the performance of electrodes. Here we analyse the 3D structure of thick cracked electrodes for the first time, using X-ray computed tomography. We show that mud cracking enhances the performance of Li-ion electrodes at discharge rates above 1 C and evaluate the implications on ion transport of different crack geometries by analysis of Euclidian distance maps.