With the ever-increasing demand for new and improved battery materials, efficient characterization methods to obtain precise insights into both raw materials and fully assembled batteries are more important than ever.
Since most modern battery materials are crystalline, and the crystallinity and crystal structure can have significant influence on a material’s performance, X-ray diffraction (XRD) is one of the go-to methods both for operando measurements on assembled batteries, and for ex-situ investigation of raw materials or recycling products.
The large variety in battery materials, and the many different shapes and sizes commercial batteries come in, pose certain challenges on XRD hardware. Since many new active materials only show slight structural differences compared to established materials, such as the substitution of cobalt in LCO with similarly sized nickel and manganese to obtain NMC, high quality diffraction data that allows precise determination of lattice parameters is essential.
Many of the metals commonly used in battery active materials show X-ray fluorescence with Cu Kα radiation, which is one of the most common radiation types in XRD. Additionally, high-energy (hard) X-rays are required to penetrate the airtight metal housings surrounding assembled batteries. For this reason, the availability of high-energy X-ray sources (e.g. molybdenum or silver), and suitable optical components, is crucial. The ability to exchange different X-ray sources quickly, and align them automatically, drastically increases the efficiency of modern X-ray diffractometers.
Dedicated battery sample holders that allow precise positioning and reliable electrical connection of batteries for operando measurements round off the requirements for modern, high-quality XRD diffractometers for battery analysis.
In this presentation, a variety of challenges and solutions in XRD on batteries will be discussed, covering both operando measurements on fully assembled batteries and ex-situ analysis of raw materials. An overview of the state-of-the art in XRD on batteries, from cell assembly to sample holders and measurement setup will also be presented.