In situ x-ray photoelectron spectroscopy analysis of electrochemical interfaces in battery: Recent advances and remaining challenges

Abstract

An in-depth understanding of charge transfer processes at the electrochemical interfaces is a critical knowledge gap impeding the design of energy storage materials. X-ray photoelectron spectroscopy plays an important role in analyzing electronic structures of heterogeneous interfaces, such as electrode-electrolyte interphases. Correspondingly, ex situ studies based on postmortem analysis of electrode materials using x-ray techniques are widely reported in the literature but often fail to capture intermediate and transient species, which are critical for a predictive understanding of the charge transfer process. The lack of extensive in situ/operando x-ray analysis of buried interfaces in energy storage systems can be mainly attributed to technical limitations, such as the requirement of high vacuum conditions. However, in the past decade, considerable efforts have been devoted to overcoming these technical barriers and enable investigation of the solid/solid and solid/liquid interfaces. This review catalogs some of the recent progresses and new experimental designs in the application of in situ and operando x-ray photoelectron spectroscopy toward characterizing interfacial processes and emergent properties, which can help build the design strategy for advanced batteries. The remaining challenges and future research directions are also discussed, as potential paths forward in this field.

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials

“…provide invaluable information about the morphology, surface composition and oxidation state, and crystallographic orientation, these techniques are often performed ex situ and operando , which can result in some surface changes due to changing the surface atmosphere of the electrode. However, some methods have been developed to obtain as close to in situ data as possible using ultrahigh vacuum systems but have a focus on surface characterization rather than in situ electron transfer reactions. , In order to gain a full understanding of the electrode surface properties, electroanalytical techniques are needed to elucidate the electron transfer properties. SECM has become a versatile technique used for a number of different systems including corrosion, , electrocatalysis, and photoelectrocatalyis among many others.…”

Synchrotron radiation based operando characterization of battery materials

“…For the same risk of altering composition and redox states, caution must be used in depth profiling studies assisted by sputtering. 96 The non-destructive depth profiling offered by varying the photon energy with a synchrotron source is particularly attractive, as the electrode surface is often the subject of interest (investigation of passivation and SEI layers, which may exhibit a complex composite gel-like structure). In these cases, manipulation may still largely affect surfaces, and ensuring representativity is not straightforward.…”

Li-ion solvation in TFSI and FSI -based ionic liquid electrolytes probed by X-ray photoelectron spectroscopy

“…When explicitly investigating the surface and interface modifications, X-ray photoelectron spectroscopy (XPS) is routinely employed and considered to be one of the suitable characterization techniques for LiBs allowing to study the interface evolution occurring on cycled electrodes. [2,3] The advantage of the XPS is the surface sensitivity providing direct information of the by-product species related to the electrolyte stability, in both liquid [4] and solid [5], [6], [7] -based electrolytes. Furthermore, by probing the active materials, XPS offers the possibility to identify the potential dependency of their oxidation states and redox reactions.…”