Scheme 1. The schematic representation of the structural origin of the capacity enhancement in ZIF glass anode.

Operando powder X-ray diffraction (PXRD) is a widely employed method for the investigation of structural evolution and phase transitions in electrodes for rechargeable batteries. Due to the advantages of high brilliance and high X-ray energies, the experiments are often carried out at synchrotron facilities. It is known that the X-ray exposure can cause beam damage in the battery cell, resulting in hindrance of the electrochemical reaction. This study investigates the extent of X-ray beam damage during operando PXRD synchrotron experiments on battery materials with varying X-ray energies, amount of X-ray exposure and battery cell chemistries. Battery cells were exposed to 15, 25 or 35 keV X-rays (with varying dose) during charge or discharge in a battery test cell specially designed for operando experiments. The observed beam damage was probed by µPXRD mapping of the electrodes recovered from the operando battery cell after charge/discharge. The investigation reveals that the beam damage depends strongly on both the X-ray energy and the amount of exposure, and that it also depends strongly on the cell chemistry, i.e. the chemical composition of the electrode.

No abstract

Operando powder X-ray diffraction (PXRD) is a widely employed method for investigation of structural evolution and phase transitions in electrodes for rechargeable batteries. Due to the advantages of high brilliance and high X-ray energies, the experiments are often carried out at synchrotron facilities. It is known that the X-ray exposure can cause beam damage in the battery cell resulting in hindrance of the electrochemical reaction. In this study, we investigate the extent of X-ray beam damage during operando powder X-ray diffraction synchrotron experiments of battery materials with varying X-ray energies, amount of X-ray exposure and battery cell chemistries. Battery cells were exposed to 15, 25, or 35 keV X-rays (with varying dose) during charge or discharge in a battery tests cell specially designed for operando experiments. The observed beam damage was probed by µPXRD mapping of the electrodes recovered from the operando battery cell after charge/discharge. Our investigation reveals that beam damage depends strongly both on X-ray energy, amount of exposure and that it depends strongly on the cell chemistry, i.e. the chemical composition of the electrode.

The limited availability of raw materials for the production of Li-ion batteries creates a strong incentive to develop Na-ion batteries due to the higher abundance of sodium raw materials. Layered transition-metal oxides are among the most promising electrode materials for Na-ion batteries due to their high capacities. Unfortunately, they still suffer from poor capacity retention. Furthermore, for the Na-ion battery technology to be truly sustainable, the Na-ion electrodes must be free of scarce elements like Ni, Co, and Li (often used as stabilizing dopants). This study investigates the sustainable materials P2-Na x Fe y Mn1–y O2 (y = 0.33 and 0.5) to correlate the structural evolution during Na-ion extraction and insertion (i.e., battery charge and discharge) to the Fe:Mn ratio. Using operando powder diffraction, we map the complete structural evolution during deep charge and discharge. Through a combination of Rietveld refinement and pair distribution function analysis, structural models for the distorted and disordered phases at deep discharge and charge are deduced at a global (average) and local scale. By combining the overview of the full structural evolution with the details from the structural analysis, insight into the effects of the Fe:Mn ratio and the origin of phase transitions are elucidated.