Electrode Coating and Electrolyte Dependent Intercalation Rates and Activation Energies of Lithium-Ion Battery Electrodes

Lithium-ion batteries continue to be an attractive choice for electronics and larger sustainability applications, however the reaction kinetics of various chemistries are poorly understood. The intercalation rates determine the power densities of Li-ion batteries, but the energy barriers and microscopic interfacial processes are not known. Here we understand and model the electrochemical intercalation kinetics of various electrode-electrolyte interfaces through systematically tested experiments on a list of thin oxide electrodes (LiCoO2, LiNixMnyCozO2 materials) with controlled surface coatings and different organic electrolytes. Through temperature-dependent measurements, we extract the activation energy for moving an ion near the intercalation material interface and intercalating the ion, where LiCoO2 electrodes shows higher activation energy than LiFePO4 and LiNixMnyCozO2 electrodes, and LiCoO2 in LiPF6-containing electrolytes gives similar action energy compared to LiClO4-containing electrolytes. The coupled-ion electron transfer theory is used to extract the reorganization energy and reaction rates which can be used to predict materials with optimal kinetic properties for electrified interfaces. These results provide a fundamental understanding of ion intercalation kinetics and new directions for interfacial engineering of Li-ion batteries to boost power density.