In Situ Characterization of the Solid Electrolyte Interphase in Lithium Ion Batteries

Abstract

The increasing global energy demand has fueled considerable effort into improving upon current energy storage technologies to keep in step with this demand. Improving current energy storage technologies, such as lithium ion batteries (LIBs), requires insight and understanding of the fundamentals of their operation. A key component of LIBs is the solid-electrolyte interphase (SEI), which develops at the interface between the electrode and the electrolyte as a result of reaction with, and degradation of, the battery electrolyte [1]. This passivating layer is vital to the operation and performance of batteries, but little is known of its exact structure since these electrode/electrolyte interfaces are buried deep within the battery, and so are difficult to “look” at using standard characterization techniques [2]. So-called “post-mortem” studies, which involve taking batteries apart inside a glove box, are methodologically simple, but may alter the SEI surface chemistry due to exposing highly reactive materials to contaminants inside a glove box.Here we introduce a platform for in situ characterization of electrode/electrolyte interfaces, capable of operation and disassembly of LIB components (anode, cathode and electrolyte) completely in situ without the need to transfer materials to a glove box prior to characterization. We demonstrate the capabilities of the platform using interface sensitive techniques, including data from one of the first lab-based hard X-ray photoelectron spectrometers, which is based at the Henry Royce Institute at the University of Manchester. Electrochemical data is also presented, demonstrating the electrochemical characterization abilities of the platform, and shows potential for extending beyond studies of LIB technology.