Unraveling and applying quantitative cross-scale understanding of energy storage systems

Abstract 
Quantitative atomic scale and molecular level insight into the chemical and structural/morphological  properties on an absolute scale and under reaction conditions is imperative for understanding  mechanisms and phenomena across scales in (electro)chemical (energy storage) systems. Interpreted in the context of the respective device performance, this knowledge can be used for rational design of and new concepts for improved materials and processes. Following a brief introduction, an overview of novel operando-capable X-ray-based methods (some developed by us) and a rationalization of their particular usefulness for studying electrochemical systems, and several examples using model systems, three topics will be discussed in detail.  

The three topics are: (1) Charge and mass transport in electrolytes, studied via correlative (coherent)  operando X-ray techniques combined with theory and simulation to quantify and understand transport  properties. (2) Surface-(electro)chemistry in Li-ion batteries, revealing that LiF in the solid electrolyte  interphase nucleates via electrocatalytic HF reduction and subsequent PF6- anion reduction, and  leveraging this insight to selectively remove HF from LIB electrolytes. (3) Desalination and separation  batteries, where operando high-energy X-ray diffraction microscopy resolves ion intercalation processes and ion selectivity in manganese oxide and iron phosphate electrodes.