X-ray analysis to enhance battery development
Scientists in universities and industries use X-ray technologies to improve battery development. Technologies like X-ray diffraction, X-ray Fluorescence, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy are analysis methodologies that improve the understanding of battery materials. Insights can be used to improve charge capacity, enhance lithium-ion battery recycling or even to switch to other more abundant materials.
X-ray Diffraction (XRD) in battery development
The crystalline phase of material is defined by its crystal structure at atomic scale – the scale at which ionic or electronic transport happens or is hindered. The composition of crystalline phases defines the overall electrode material quality and its suitability for battery cell manufacturing. X-ray diffraction is the technique of choice when it comes to the analysis of crystalline phases as it can determine the crystal structure and / or identify crystalline phase.
In operando X-ray diffraction can investigate the battery charge/discharge mechanisms by analyzing underlying crystal structure changes during battery cycling. In particular, our Empyrean XRD platform can be used for the in operando cycling of various types of battery cells – from coin or electrochemical cells to pouch and prismatic cells.
Our Empyrean XRD platform enables battery manufacturers and developers to investigate electrode materials and assembled coin, electrochemical, pouch, and prismatic cells within situ charge-discharge cycling.
Aeris compact X-ray diffractometer, an easy-to-use instrument with superb data quality, can be used for accurate analysis of:
- Crystalline phase composition and presence of any residual reactants (optimization of calcination process)
- Crystallite size (related to the primary particle size)
- Degree of graphitization in synthetic anode graphite
X-ray Fluorescence (XRF) in battery development
Batteries are built out of different elements, where the different compositions determine the final performance of the battery. For example, the ratio of Nickel, Cobalt and Manganese determines the final capacity and recycling properties. X-ray fluorescence is an easy technology to determine the composition, and it is able to measure the chemical composition and impurities from a few ppm up to 100% levels. It is an alternative technique to ICP.
For major elements at a few % levels, XRF provides a simpler and more accurate way of measuring elemental composition than ICP as it does not require any sample dilution or acid digestion. Many leading battery companies use XRF to analyze cathode and precursor materials.
Malvern Panalytical has several XRF solutions in its portfolio delivering the composition analysis battery researchers’ and manufacturers’ needs, ranging from Energy Dispersive Epsilon Benchtops to the floorstanding Wavelength Dispersive Zetium.
X-ray photoelectron spectroscopy (XPS)
X-ray photoelectron spectroscopy is a surface-sensitive technology that helps battery research to understand structural changes happening at battery materials and interfaces. As batteries are built up out of different parts, like electrodes, cathode, anode and electrolyte there are different interfaces in one cell. In a battery during charging and discharging redox reactions happen, and these can change the elemental structure at the interface. For example, did the oxidation state of an element change due to the different cycles?
XPS systems are available for laboratories and are one of the common tools used by material scientist to enhance their research.
X-ray absorption spectroscopy (XAS)
X-ray Absorption Spectroscopy (XAS) is commonly used in a wide range of battery research (i.e. Li/S, Na, solid-state batteries) to study the electrochemical and structural properties of:
- Cathodes
- Anodes
- Electrodes
XAS can help battery researchers collect an in-depth understanding of structural and electrochemical properties in batteries. It can give crucial insights into what happens and leads to crucial problems, such as reaction mechanisms, degradation phenomena and structural evolution upon cycling and ageing. In addition to a technique such as XPS, XAS are able to measure reactions in bulk material.
One type of use is to understand the redox reactions of batteries better. A typical Li-ion cell consists of two electrodes inserting and de-inserting Li at the cathode at higher, and anode at lower redox potentials, respectively. Li ions migrate through the electrolyte (liquid absorbed into a porous separator or solid or gel). The electrodes are composite systems, made of proper amounts of electroactive materials. Over time many different redox-active systems have been developed, both for the anode and cathode and various categories of electrolytes, leading to cells with different performances in terms of capacity, energy and power density, lifetime and cycling behavior.