To meet growing energy demands, degradation mechanisms of energy storage devices must be better understood. As a non‐destructive tool, X‐ray Computed Tomography (CT) has been increasingly used by the battery community to perform in situ experiments that can investigate dynamic phenomena. However, few have used X‐ray CT to study representative battery systems over long cycle lifetimes (>100 cycles). Here, the in situ CT study of Zn–Ag batteries is reported and the effects of current collector parasitic gassing over long‐term storage and cycling are demonstrated. Performance representative in situ CT cells are designed that can achieve >250 cycles at a high areal capacity of 12.5 mAh cm−2. Combined with electrochemical experiments, the effects of current collector parasitic gassing are revealed with micro‐scale CT. The volume expansion and evolution of ZnO and Zn depletion are quantified with cycling and elevated temperature testing. The experimental insights are utilized to develop larger form‐factor (4 cm2) cells with electrochemically compatible current collectors. With this, over 500 cycles at a high capacity of 12.5 mAh cm−2 for a 4 cm2 form‐factor are demonstrated. This work demonstrates that in situ X‐ray CT used in long cycle‐lifetime studies can be applied to examine a multitude of battery chemistries to improve performances.

Lead halide perovskites are among the most exciting classes of optoelectronic materials due to their unique ability to form high‐quality crystals with tunable bandgaps in the visible and near‐infrared using simple solution precipitation reactions. This facile crystallization is driven by their ionic nature; just as with other salts, it is challenging to form amorphous halide perovskites, particularly in thin‐film form where they can most easily be studied. Here, rapid desolvation promoted by the addition of acetate precursors is shown as a general method for making amorphous lead halide perovskite films with a wide variety of compositions, including those using common organic cations (methylammonium and formamidinium) and anions (bromide and iodide). By controlling the amount of acetate, it is possible to tune from fully crystalline to fully amorphous films, with an interesting intermediate state consisting of crystalline islands embedded in an amorphous matrix. The amorphous lead halide perovskite has a large and tunable optical bandgap. It improves the photoluminescence quantum yield and lifetime of incorporated crystalline perovskite, opening up the intriguing possibility of using amorphous perovskite as a passivating contact, as is currently done in record efficiency silicon solar cells.

Correlative X‐ray microscopy, including synchrotron X‐ray diffraction and fluorescence, is leveraged to understand the local role of europium as a B‐site additive in CsPbBr3 perovskite crystals. Europium addition reduces microstrain in the perovskite, despite the fact that the degree of europium incorporation into the perovskite varies locally, with a maximum loading over twice the nominal stoichiometry. The presence of europium improves photoluminescence yield and bandwidth, while shifting the emission to bluer wavelengths. Finally, europium‐containing crystals have greatly improved X‐ray hardness. The findings show promise for europium as an additive in perovskite optoelectronic devices.

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Printable AgO-Zn batteries are highly attractive for wearable devices for their safe chemistry, high energy density, and rechargeability. However, silver dissolution from AgO cathodes limits the shelf life and cycle life of primary and secondary AgO-Zn cells. In this study, factors including electrolyte, cell configuration, and cycling rate on silver dissolution were investigated systematically via precise identification and quantification of dissolved silver species in AgO-Zn cells. The mechanism of silver dissolution is studied by characterizing both dissolved silver species and cathode surfaces with chemical analysis including Raman spectroscopy, X-ray photoelectron spectroscopy, and Xray absorption spectroscopy. We found that reducing the complexation step within the two-step reaction of AgO to [Ag(OH) 2+x ] −x is key to mitigating the silver dissolution, which can be controlled by selecting the proper electrolytic species as well as cycling rate and creating rough surfaces of cathodes.

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