Tracking Passivation and Cation Flux at Incipient Solid?Electrolyte Interphases on Multi?Layer Graphene using High Resolution Scanning Electrochemical Microscopy

The solid electrolyte interphase (SEI) is a dynamic, electronically insulating film that forms on the negative electrode of Li+ batteries (LIBs) and enables ion movement to/from interface while preventing breakdown. However, there limited comparative understanding LIB SEIs with respect to those formed Na+ K+ electrolytes for emerging battery concepts. We used scanning electrochemical microscopy (SECM) in situ interfacial analysis incipient Li+, multi-layer graphene. Feedback images using 300 nm SECM probes ion-sensitive measurements indicated superior passivation highest cation flux Li+-SEI contrast K+-SEIs. Ex X-ray photoelectron spectroscopy significant fluoride formation only Na+-SEIs, enabling correlation measurements. While SEI chemistry remains complex, these electroanalytical methods reveal links between chemical variables properties materials energy storage.