Controlling expansion in lithium manganese oxide composite electrodes via surface modification

Electrodes experience significant mechanical degradation at fast charging/discharging rates, ultimately leading to particle fracture and capacity loss. In this work, we investigate the role of an Au surface coating on the intercalation-induced strain changes in lithium manganese oxide (LiMn₂O₄, LMO) composite cathode electrodes. In-situ strain measurements are performed on free-standing composite electrodes to monitor lithium intercalation-induced deformations in the electrode. Interestingly, expansion in the Aucoated LMO electrodes are significantly smaller than LMO electrodes (without coating) at faster scan rates. Strain evolution is predicted based on elastic properties of the composite electrode and the intercalation-induced crystal structure changes in the LMO particles. Our results reveal that expansion can be controlled through coatings, suggesting promising material-based strategies to improve lifetime and performance of the batteries.