Spectro Inlets instrument adapted as part of PhD research project to develop longer-lasting batteries
An ultra-sensitive technique for analysing the trace amounts of gases that evolve as lithium-ion batteries operate has been created and incorporated into a commercial instrument. The technique is helping to develop a better understanding of the reasons why the performance of batteries decreases over time, with the aim of developing fture generations of EV batteries with longer lifetimes.
Dr Daisy Thornton, previously a PhD researcher at Imperial College London and member of the Faraday Institution’s Degradation project, her supervisors Professor Ifan Stephens, (and co-supervisors by Professor Mary Ryan and Dr Ainara Aguadero) and a development engineer at Spectro Inlets adapted the electrochemical mass spectrometry (EC-MS) standard cell to fit Daisy’s experiments. This new cell could offer researchers new insights into how and why batteries degrade over time. The innovation was incorporated into commercial product by the Danish company.
“Understanding the gas evolution in Li-ion batteries offers an insight into degradation mechanisms. It’s important to have a technique that has good time resolution that you can use while the battery is operating. This allows researchers to see the exact potential, quantity and rate at which trace amounts of gases evolve, which can act as a signature of certain harmful reactions taking place within the battery,” says Daisy.
Existing techniques have limitations, and Daisy’s research evolved into creating a new cell for the Spectro Inlets EC-MS system, because “the Spectro Inlets on-chip EC-MS system seemed like a suitable candidate to accurately and precisely monitor parasitic gas evolution.”
| By the numbers | |
|---|---|
| At least two orders | of magnitude higher sensitivity to gases such as hydrogen or oxygen |
| 2 and 3 | new postdocs and PhD researchers respectively at Imperial using the adapted cell |
| 3 | funders aligned to facilitate the research on the project* |
*Ifan Stephen’s group initially used the Henry Royce Institute’s Spectro Inlets EC-MS instrument at Imperial and later purchased a dedicated instrument as part of a European Research Council grant, which yielded the majority of results for Daisy Thornton’s thesis.
Adapting the EC-MS Technique for Sensitive Measurement of Gas Evolution in Batteries
Dr Daisy Thornton in the laboratory.
The standard cell sold with the Spectro Inlets instrument had been designed for aqueous electrolytes for applications such as water electrolysis. However, it was unsuitable for the non-aqueous electrolytes used in Daisy’s PhD project. Aiming to develop a better solution, the team at Imperial and Spectro Inlets designed a cell suitable for Li-ion battery analysis that could fit in the Spectro Inlets EC-MS instrument with a mesh working electrode that sits parallel to the counter electrode.
The new adapted cell is better suited for analysing gas evolution than others on the market. Other techniques such as differential electrochemistry MS lose some of the electrolyte and target gas analytes (the species being identified and measured). However, the new cell collects 100% of the analyte species, which allows all the electrolyte in the cell to be retained, and has no gases flowing through the cell, which would complicate the analysis.
The result is a more sensitive analysis of gas evolution mechanisms. The cell developed by Daisy and co-inventors has a microfabricated membrane that creates a well-defined interface between the liquid environment of the cell and vacuum environment of the MS instrument. Daisy continues, “it very precisely controls the flow of the analyte you’re trying to measure through a capillary in the membrane chip.”
Daisy states that the technique stands out due to its “preciseness, accuracy, sensitivity, time resolution, and the fact it comes as a full package with data analysis capabilities.” Ifan adds that “the sensitivity is two orders of magnitude higher to gases such as oxygen or hydrogen than people have previously measured.”
The Faraday Institution Degradation Project is continuing to use the cell to determine accurate rates of specific degradation mechanisms to better predict the useful remaining life of batteries. The team is investigating the mechanisms of gas generation in various battery systems, including sodium-ion batteries and “anode-less” lithium batteries.
Ifan Stephens’ group is also using the cell to measure electrochemically produced ammonia as a sustainable alternative to the Haber-Bosch process.
Commercialisation
The jointly developed cell has already been sold in both European and US markets.
Anne Dyrdal, Head of Sales, Spectro Inlets commented, “we saw potential in delivering a product that could bring value to a new market in battery research and development. It gives us the ability to direct our products into the battery manufacturing sector – so it has a high potential.
“The joint technology we made with Imperial is for a coin cell battery assembly where the sample holder fits on to our existing technology. We have now developed a feature with the instrument that saves the customer needing to put the entire EC-MS into a glove box for the protective atmosphere.”
Looking to the future
The response from Spectro Inlets customers has been positive. As an example, Johnson Matthey has acquired an EC-MS and is now using it for spectroelectrochemical diagnostics across wider applications including for hydrogen technologies research.
While the recent focus has been on the analysis of Li-ion batteries, the apparatus was originally designed for aqueous applications, especially water electrolysis and corrosion studies. The new cell adaptation for the EC-MS technique has shown promise for analysis of non-aqueous battery technologies, as well as wider electrochemical applications. Sodium-ion and aqueous zinc batteries have already been used with the EC-MS system.
While this jointly-developed cell was specifically designed for coin cells, Spectro Inlets have plans to develop sample holders for pouch cells and solid-state batteries.
The Spectro Inlets electrochemical mass spectrometry (EC-MS) system.
Read more about the Spectro Inlet EC-MS to analyse battery gases.
Read Daisy Thornton’s Faraday Pathway outlining her experience of the Faraday Institution PhD Training Programme and move to Rimac Energy as Cell Degradation Engineer post-PhD.
Case study published May 2024.