03rd February 2021 | Author: Alexandra Stavropoulou
We live in the era of portability; cords and wires are used less and less for powering up devices and consumer electronics (laptops, mobile phones, toothbrushes, torches, etc.). We also live in the era of ‘e-mobility’ or electrification. Electric vehicles (EVs) are the highly anticipated mobility alternative for a zero-emission, greener future. Battery innovation is significantly driven by the development of batteries for EVs, which must be long-lasting, safe, fast charging and, of course, provide a fair distance vehicle autonomy between charges. EVs are not only cars, but also bikes, scooters, buses, trucks (light and medium duty) and boats. Projects to make planes electric are in progress.
Besides mobility, batteries are key to energy storage. They open the way to harvest renewable energy sources (solar, wind, hydro, biomass, tidal, and geothermal energy). The cost for utility-scale battery storage in the US has dropped 70% (from $2,152/kWh to $625/kWh) between 2015 and 2018 (US Energy Information Administration). It is expected to drop even lower (another 45%) by 2030 (US National Renewable Energy Laboratory).
However, there are challenges in battery design which must be overcome in order to realise this zero-emission future. The challenges to develop suitable batteries are different at environmental temperature extremes. Ongoing experimentation with new materials, intending to improve efficiency and tackle known issues, adds new complexity to the mix as battery materials are required to have predictable behaviour for maximum safety.
Spent EV batteries can have a second life in energy storage applications before they are eventually recycled. This approach is part and parcel of competitive sustainability and circular economy. Besides, it ensures that materials stay in circulation rather than being constantly mined and then discarded.
So, how can batteries become more powerful and reliable?
Everything starts with effective material characterisation, from raw materials mining to the final product. The materials destined to become battery components are required to be free of impurities or any other accidentally introduced contamination, which could undermine materials performance or compromise safety.
Energy dispersive spectroscopy (EDS) is a quick, non-destructive, and non-invasive technique, with high sample throughput – ideal for performing efficient material screening. The electrode precursor material is in powder form. For cathodes, this powder is commonly a mix of nickel, cobalt, and manganese (NCM), but aluminium is often included. There is a tendency to replace cobalt due to cost fluctuations and controversial mining practices. New compositions are constantly being tested to find the optimal recipe. The quality assurance and control of these powders is essential to ensuring material performance and lifetime. AZtecBattery® offers an automated SEM-EDS system for controlling powder composition and detecting contamination. The are many benefits to using AZtecBattery:
1. automation - no instrument downtime
2. reliable characterisation (morphology, particle size, particle count, composition)
3. morphological and compositional characterisation of >30,000 particles/hour with Ultim Max
4. morphological measurement of >1,000,000 particles/hour
5. particle reconstruction for large particles extending to multiple fields of view
6. high sample throughput
7. customisable preset classification schemes
8. user profile: sharing analytical profiles across sites for enhanced consistency
9. user-friendly interface with navigators and step notes to help new users
10. custom results reporting
Battery materials are often beam sensitive. In that case, a low beam accelerating voltage is recommended to avoid damaging the sample. If the sample suffers beam damage, then the analysis is accurate, but it will reflect the beam damage on the sample (secondary) and not the primary map composition. Such an example is presented in the images below. Beam damage is obvious with secondary phases forming on the sample surface in an attempt to analyse Lithium.
Left: Area imaged before analysis. Right: Same area imaged again after analysis.
Ultim Extreme is a windowless detector designed to operate at low accelerating voltage and produce high resolution images. It is a sensitive and powerful detector and is the first EDS detector that is capable of consistent detection of elements as light as lithium. As such, its application range extends from life sciences to materials science and includes battery research and development.
The need to correlate data from different instruments and techniques is acknowledged more and more. This is particularly applicable in the battery industry because certain material properties cannot be directly measured, but they can be inferred. Our recent webinar explores this topic in more depth and covers a range of complimentary techniques that allow thorough interrogation of battery materials to ensure the highest quality battery product is produced. View now.
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Burgess, Simon, Xiaobing Li, and James Holland. "High spatial resolution energy dispersive X-ray spectrometry in the SEM and the detection of light elements including lithium." Microscopy and Analysis 6 (2013): S8-S13.
Hovington, P., Timoshevskii, V., Burgess, S., Demers, H., Statham, P., Gauvin, R., & Zaghib, K. (2016). Can we detect Li KX‐ray in lithium compounds using energy dispersive spectroscopy?. Scanning, 38(6), 571-578.
Reed, S. (2005). Electron Microprobe Analysis and Scanning Electron Microscopy in Geology (2nd ed.). Cambridge: Cambridge University Press. doi:10.1017/CBO9780511610561Links