Raw materials used in battery development
The process of developing a battery begins with mining the needed ores from the earth, followed by processing those ores into high-quality minerals or pure elements, which can then be used to form a chemical slurry that is used in the final product. All the internal components of a battery—the anode, cathode, electrolyte, current collectors and separator—are essential to its ability to function. The compounds and metals that compose the electrolyte, the current collectors the graphite or metal oxide of an electrode, need to be tested for their suitability from the time they are mined to the moment they are incorporated into the final product. A key tool in maintaining proper manufacturing process control is X-ray fluorescence spectroscopy, commonly referred to as XRF.
Battery development benefits from XRF materials analysis
Common components of modern batteries include nickel, cobalt, iron phosphate, graphite (carbon), manganese, and most notably, lithium. Typical cathode chemistries of lithium-ion batteries in use today are LFP (lithium iron phosphate, LiFePO4), NMC (lithium-nickel-manganese-cobalt-oxide, LiNiMnCoO2) or NCA (lithium nickel cobalt aluminum oxide, LiNiCoAlO2). The vast majority of lithium-ion batteries use graphite powder as an anode material. Irrespective of the cell chemistry, the materials entering a battery are strictly controlled for their purity during all stages of the production process. All these elements with the exception of lithium can be analyzed via X-ray fluorescence spectroscopy during mining of these compounds and metals and during the battery development process. manufacturing process control
An analysis of some of the individual steps and elements involved in battery development helps illuminate just how useful and economically beneficial XRF can be.
A brief summary of XRF
When illuminated with X-ray radiation, different elements can be identified by the characteristic fluorescent energy that they emit.
Thermo Scientific XRF lab spectrometers can quantify up to 90 elements in liquid or solid samples of mining materials, enabling control of ore body content for refinement and processing.
Each of the elements present in a sample produces a set of characteristic fluorescent X-rays (“a fingerprint”) that is unique for that specific element, which is why XRF spectroscopy is an excellent technology for qualitative and quantitative analysis of material composition.
For a more thorough explanation, check out our Lab XRF eBook.
Mining process control improvements
The advantages begin at the mining process control stage: a keyway to improve cost-efficiency in mining is to maximize the recovery of high-quality ore. This can reduce waste from lower-quality ore and improve process efficiency, and even reduce the environmental impact of mining. Because X-ray fluorescence spectroscopy can be used for determining the concentration and distribution of elements in rocks, soils and sediments, it is adept at identifying and recovering the most economically viable resources.
One requirement to achieve high levels of high-quality ore recovery is fast and accurate elemental analysis. Thanks to simple and fast sample preparation and because XRF can assess dozens of elements in just a few minutes, mining process control operators are able to respond to results quickly and sort the processed ores according to their quality earlier than if other time-consuming analyses were used. Also, knowing the elemental composition can help the mining operations avoid unwanted “poison” elements in the ores that may negatively impact recovery of the wanted elements; this would also impact the price.
Types of XRF and their respective advantages
There are two main types of XRF analysis, energy dispersive X-ray fluorescence (EDXRF) and wavelength dispersive X-ray fluorescence (WDXRF). The two techniques often work as complements to each other. EDXRF is an analysis tool requiring minimal infrastructure, which makes it suitable to be located closer to sampling site and away from the main mining lab. WDXRF provides high precision and accuracy and is used in particular for analysis of shipping ores (for example, to analyze the composition accurately to determine the sales price).
Depending on the mine site either type of XRF may be used, EDXRF or WDXRF. In a very remote mine site with little electrical power, the ore can be checked for composition with EDXRF in order to decide where to dig. The analysis is performed without the need of a vacuum pump, thus with limited electrical need. Read our app note, EDXRF Analysis of Nickel Ore as Pressed Powders in an Air Environment, to learn more. manufacturing process control
In other larger mine sites, nickel ore is analyzed using WDXRF to determine its chemical composition with high accuracy and minimum sample preparation. In this case, the analysis is performed in vacuum in the spectrometer chamber which means better performance for the lighter elements like sodium, magnesium and aluminum. For more detail, see our app note Analysis of Nickel Ore with the ARL OPTIM’X.
Elements used in batteries are assessed using XRF manufacturing process control
Knowing the exact composition of iron ore will tell where to dig and can aid in its refinement. This topic is discussed in the app note Iron ore analysis with the ARL OPTIM’X XRF Spectrometer.
The transition metal manganese is particularly critical element in Li-ion battery cathodes, where it is used in nickel manganese cobalt (NMC) materials. An application note illustrating the suitability of the ARL OPTIM’X Spectrometer for the analysis of manganese ore samples is available here.
One of the most common elements used in batteries, Lithium cannot itself be directly analyzed via XRF. The process for recovering lithium from ore can vary based on the specific mineral deposit where it is found.
In the case of lithium recovery from salars, the lithium salts are dissolved with large quantities of water. This brine is then stored in evaporation ponds where the salt content increases due to the water evaporation. Analysis of the concentration levels in the brine at regular intervals allows controlling the process. XRF analysis is very useful in this case as the brines can be analyzed directly without further sample preparation, which is not the case for other techniques like AAS or ICP.
Graphite, the most common material used for anodes in lithium-based batteries, must be highly pure to be effective. The speed and reduced sample preparation of XRF will help provide the needed quality assurance. When testing graphite purity, typical limits of detection for potential contaminants after an analysis time of only 100 seconds can be as low as 0.13 ppm for iron or 0.10 ppm for nickel. You can read more about this in the app note, Analysis of Traces in Graphite.
Manufacturing process control can directly affect the profitability and sustainability of a company. Proper control can bring substantial energy savings, increase ore recovery, and optimize product mix. From mining of ores to battery development, XRF provides the fast and accurate analysis that is needed to maximize production efficiency and deliver the materials we depend on in our modern society.
Christina Drathen is a Product Manager for X-ray flourescence spectroscopy for Thermo Fisher Scientific
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