Elevating lithium-ion battery quality with spectral analysis

Hayley Everett

As demand for lithium-ion batteries increases, how can spectral analysis ensure quality and performance?

Liquid electrolytes play a key role in the performance and lifetime of batteries. The electrolyte fluid within lithium-ion batteries enables the efficient intercalation of lithium ions between the electrodes. The quality of the electrolyte is therefore essential, as impurities can affect the function and safety of the energy storage system.

“Rechargeable batteries have become an indispensable component in many industries, including automotive, aerospace and energy storage,” says Simon Taylor, Segment Business Development Manager at Mettler Toledo, a global supplier of precision instruments and services. “Their long-term performance and stability are critical factors in determining the efficiency and reliability of these applications. To optimise battery design and performance, manufacturers need accurate and precise analytical tools to measure and analyse various chemical and physical measurements. UV-Vis spectroscopy is one such tool that can provide valuable insights into product performance and lifetime.”


Ultraviolet-visible (UV-Vis) spectroscopy is a widely used technique in many areas, from bacterial culturing, drug identification and chemical research, to quality control in the beverage industry and, in this particular case, analysing the performance and lifetime of lithium-ion batteries for electric vehicles (EVs). Generally, the technique works by measuring the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample in comparison to a reference or blank sample.

Mettler Toledo’s compact UV-Vis spectrophotometers allow users to evaluate the suitability of electrolyte solutions easily, quickly and cost-effectively. Built-in reference scales provide ready-to-use results, while a colour guide and webinar make it easy to get started.

“UV-Vis spectroscopy is a versatile technique that lends itself well to a multitude of analyses – from testing metal ion purity of raw materials to predicting electrolyte stability and performance to ensuring compliance with wastewater regulations,” Taylor continues. “Its capability to provide accurate and precise measurements of chemical and physical properties is the reason why battery scientists trust spectroscopic techniques in quality control.”

The company’s compact EasyPlus UV-Vis spectrophotometer is a simple and cost-effective method for analysing electrolyte solutions. The instrument measures electrolyte impurities in seconds without time-consuming sample preparation. The spectrophotometer’s built-in reference colour scales compare the electrolyte’s measured colour value with stored colour reference scales to detect deviations. It also measures the amount of UV and visible light absorbed or transmitted by the irradiated electrolyte solution, indicating the sample’s purity. Either method quickly provides clarity for the customer.


UV-Vis spectrophotometry is used to analyse the gradual decline in battery performance, which is known as battery degradation. By tracking changes in the absorption spectrum of the electrolyte over time, a reference curve is established. As the battery ages and its performance declines, the stored electrolyte is measured and compared to the reference curve to determine the extent of degradation. This allows engineers to predict the life of the battery with greater accuracy.

“At Mettler Toledo, we recognise the critical importance of predicting battery life for the development of future zero-emission vehicles, the development of renewable energy technology, and balancing energy needs through battery energy storage systems (BESS),” adds Taylor. “Our UV-Vis spectrophotometers offer exceptional flexibility, accuracy, and precision, allowing battery manufacturers to predict and optimise battery performance, ensuring the safety of those batteries, and driving innovation in battery technologies.”


Engineers can effectively automate their analyses with Mettler Toledo’s UV-Vis Excellence instruments using a cell changer or autosampler system. Meanwhile, productivity can be boosted with a multi-parameter system with, for example, titration and PH measurements. In this way, engineers can not only increase their analytical efficiency but also save time during the documentation and reporting process.

Overall, UV-Vis spectrophotometry is a powerful and reproducible technique engineers can leverage to determine key battery performance indicators, eliminating the need for separate colorimeters. The ability to accurately predict battery lifetime is important for several reasons, such as preventative maintenance, warranties, state of health, and effects of usage, all of which can be used to improve cell design and manufacturing. In turn, battery lifetime management plays an important role for the successful commercialisation of new EV and hybrid vehicles, which are crucial to the transport sector’s ongoing pursuit of decarbonisation.






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