What Lies Beneath? Probing Buried Interfaces in Working Batteries

Development of in-situ and operando cells for probing buried interfaces in working batteries, portable across different characterisation instruments and applicable to a broad range of battery architectures/chemistries.

The interfaces between the active components in rechargeable batteries play a pivotal role in determining performance. This is where electrons and ions transfer between the electrodes and electrolyte during charging and discharging, and where many of the undesirable reactions that limit battery lifetime take place. Understanding how the structure and chemistry of these interfaces changes during operation is critical to developing higher capacity battery materials, fast charging protocols, and models to predict when batteries need replacing.

However, these interfaces are buried within the battery, making it extremely challenging to extract information without interference from the surrounding materials. This project investigates adapting powerful interface-sensitive methods, typically limited to vacuum conditions, so that they are compatible with battery measurements. The focus is on techniques that provide quantifiable, depth-resolved information on the chemical environment close to buried interfaces and includes X-ray photoelectron and absorption spectroscopies (XAS/XPS), second ion mass spectrometry (SIMS), and electron microscopy.

The project is pursuing both in situ cells that can be repeatedly disassembled and reassembled without breaking vacuum to allow measurement of each battery component at specific stages of cycling, and operando cells based on X-ray and electron transparent windows that allow measurement of interfaces during cycling.

Project presentation from the Faraday Institution Conference, November 2021

Milestone/deliverables (December 2021)

  • Develop and demonstrate an in-situ cell where each battery component can be removed, measured and the battery subsequently reassembled.
  • Develop and demonstrate an operando cell where the interfaces between components can be observed while the battery is charging/discharging.
  • Develop a new approach to preserving cell interfaces for further analysis.
  • Demonstrate measurement across multiple characterisation tools (including hard X-ray photoelectron spectroscopy (HAXPES), SIMS, scanning electron microscopy (SEM), and X-ray diffraction (XRD).

Project innovations

Through close interaction with Diamond Light Source and the Henry Royce Institute, the project has developed a new XPS/HAXPES technique that can be used with both lab-based systems and a synchrotron source. This adds new in-situ chemistry capability by providing a new option to react and reliably measure uncontaminated samples. It also offers an offline route for sample verification before national lab instrument beamtime. The in-situ and operando capabilities developed are expected to substantially improve researcher understanding of interfacial behaviour in a wide variety of different battery chemistries.

Project funding
£0.5m
1 July 2019- 30 September 2021
Principal Investigator
Professor Robert Weatherup
University of Oxford
University Partners
University of Oxford (Lead)
University of Manchester
Research Organisations, Facilities and Institutes
Diamond Light Source (STFC)
+ 3 Industry Partners

 

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