This article presents a versatile easy‐to‐use electrochemical cell suitable for in operando, in situ measurements of battery materials during electrochemical cycling using a variety of X‐ray techniques. Argonne's multi‐purpose in situ X‐ray (AMPIX) cell provides reliable electrochemical cycling over extended periods owing to the uniform stack pressure applied by rigid X‐ray windows and the formation of a high‐fidelity hermetic seal. The suitability of the AMPIX cell for a broad range of synchrotron‐based X‐ray scattering and spectroscopic measurements has been demonstrated with studies at eight Advanced Photon Source beamlines to date. Compatible techniques include pair distribution function analysis, high‐resolution powder diffraction, small‐angle scattering and X‐ray absorption spectroscopy. These techniques probe a broad range of electronic, structural and morphological features relevant to battery materials. The AMPIX cell enables experiments providing greater insight into the complex processes that occur in operating batteries by allowing the electrochemical reactions to be probed at fine reaction intervals with greater consistency (within the charge–discharge cycle and between different methodologies) with potential for new time‐dependent kinetic studies or studies of transient species. Representative X‐ray and electrochemical data to demonstrate the functionality of the AMPIX cell are presented.

The reversible electrochemical insertion of multivalent ions into materials has promising applications in many fi elds, including batteries, seawater desalination, element purifi cation, and wastewater treatment. However, fi nding materials that allow for the insertion of multivalent ions with fast kinetics and stable cycling has proven diffi cult because of strong electrostatic interactions between the highly charged insertion ions and atoms in the host framework.Here, an open framework nanomaterial, copper hexacyanoferrate, in the Prussian Blue family is presented that allows for the reversible insertion of a wide variety of monovalent, divalent, and trivalent ions (such as Rb + , Pb 2+ , Al 3+ , and Y 3+ ) in aqueous solution beyond that achieved in previous studies. Electrochemical measurements demonstrate the unprecedented kinetics of multivalent ion insertion associated with this material. Synchrotron X-ray diffraction experiments point toward a novel vacancy-mediated ion insertion mechanism that reduces electrostatic repulsion and helps to facilitate the observed rapid ion insertion. The results suggest a new approach to multi valent ion insertion that may help to advance the understanding of this complex phenomenon.

The solid electrolyte interphase (SEI) is a passivation layer naturally formed on battery electrodes. It protects electrodes and electrolytes from degradation and dictates charging time capabilities and lifetime. Despite its importance, it remains a poorly understood battery component. This study provides novel insights into the formation, morphology, and composition of the SEI on Si anodes through a multi-modal approach. The findings show a layered SEI and the ion and electron conductivities, as well as their relation to performance, are discussed.

In situ X-ray absorption spectroscopy along with electrochemical measurements (CV and RDE) and previously published EQCN data provide further understanding of the nature of chloride poisoning on different faces/ sites of carbon supported platinum clusters (1-2 nm) in acidic medium (HClO 4 ). Chloride is shown to adsorb in 3-fold sites on the Pt(111) faces at the investigated Clconcentrations (10 -3 and 10 -2 M). Atop chloride was found to be present within a narrow potential range (0.4-0.7 V RHE) when compressed adlayers of Clare formed on the Pt(111) faces forcing some Clto exist in atop/bridged sites. The interplay of anionic (Cl -, Br -, OH -, and HSO 4 -) adsorption on the different surfaces of Pt are also considered. For example O/OH can easily displace atop chloride on the edges/corners but not the Clat the Pt(111) sites, and therefore Cldramatically raises the overpotential for water activation at the Pt(111) sites. Chloride also drastically alters the ORR causing an increase of the overpotential by ∼85 mV for every 10-fold increase in chloride concentration with a total 150-200 mV increase in the overpotential at large concentrations at the Pt(111) sites. Finally Clions cannot displace the bisulfate overlayer on the Pt(111) faces after it is formed at lower potentials; however, once the bisulfate adsorption is disturbed at higher potentials, the bisulfate cannot displace the Cladsorption. These relative anion adsorption preferences can help to explain the different dependencies of the important ORR on anion adsorption, and suggests that the effect of Clpoisoning might be quite dependent on the Pt particle size.