Modulating Li-ion battery voltage oscillations in phase field simulations

Abstract

The discovery of voltage oscillations in Li-ion batteries has shown how complex phase separating electrodes can be. It is still poorly understood how electrode particles can act in this concerted manner to give out the oscillations, implying possible material behavior and applications are still undiscovered. For a systemic study in this direction, however, an initial understanding of how parameters impact the voltage oscillations is required. In this work, we investigate the roles of electrolyte mass transport and surface wetting on voltage oscillations. Using data from the mass transport investigation, it is discussed how particle phase transitioning is ordered by their radius and distance from the separator, shaping voltage oscillations at low discharge capacities. Special attention is drawn to electrode porosity, given its role in the interplay between intercalation kinetics and electrolyte mass transport, influencing the overall oscillation amplitude. At last, the oscillations were found to be greatly affected by surface wetting, with results predicting a 200 % increase in oscillation amplitude, and drastic changes to oscillation period and shape. The reason for this could be traced back to the exchange current, as this magnitude is dependent on surface Li+ concentration. The largest increase in amplitude and period was associated with a change in the intraparticle phase transitioning dynamics. The results are used to formulate recommendations to experimentalists on how to enhance the oscillatory response, and are also employed in reinterpreting previous experimental reports.