Controlled Electrode-Electrolyte Interphases (EEI) Formation Via Ex-Situ Interfacial Synthesis

The stability and electrochemical performance of energy storage systems are heavily influenced by their interfaces. The electrode-electrolyte interphases (EEIs) present at these interfaces are typically formed in-situ through the electrochemically induced complex interactions involving the electrode surface and bulk electronic structure, functional groups and chemical species present at the interface, and electrolyte. Given the importance of interface stability in energy storage, herein, multiple ex-situ approaches (electrochemical fluorination, ion-exchange metathesis, layer-by-layer coating) have been explored to form stable and controlled EEI that allow ion transport and limit the electron leakage. Such controlled EEI via ex-situ interfacial synthesis demonstrated significantly improved cycling stability compared to in-situ EEI formation.