Operando discrimination of fast and slow active grains within a cycling electrode for lithium battery

The impact of the formation of an electrolyte based decomposition layer on the distribution of the active grain kinetics has been investigated operando within a cycling electrode for lithium battery. It is demonstrated, from fitting procedure of the electrochemical responses and from operando XRD experiments, that as the passive film forms, slow reacting grains appear within the working electrode and operate simultaneously with faster grains. Slow grains are macroscopically distributed, presumably at the electrolyte side of the electrode. Discrimination of the electrochemical response pertaining to each type of grains allows rationalizing their contribution to the capacity fading dynamics.