Tell us about your research

I design polymers for solid-state battery cathodes as part of the Faraday Institution’s SOLBAT project. Current lithium-ion batteries have a liquid electrolyte between an anode and cathode. SOLBAT aims to create a safer, higher-performance battery by replacing the liquid electrolyte with a solid electrolyte. This would remove the flammable liquid and allow batteries to use lithium metal at the anode, which is higher energy. With a liquid electrolyte, it’s easy for all the components to remain in contact so that lithium ions and electrons can move between the electrodes. A key challenge in cathodes for solid-state batteries is that current state-of-the-art cathode materials change volume during battery charge and discharge. This causes the solid-state components to lose contact leading to loss of battery capacity. We work around this in the lab by applying a very high pressure of around 50 MPa, but this wouldn’t be practical commercially.

Polymers are flexible and can be adhesive, so they provide a way of holding the components of a solid-state battery together without needing high pressures. As components change volume, polymers can fill the voids and spring back to shape during charge and discharge. I’m working on using polymers at the cathode. One big challenge is finding a balance between the different characteristics these polymers require to work well inside a battery. They must be flexible, conductive so they don’t block the movement of lithium ions, adhesive in order to stick to the battery components, and stable in the harsh battery environment. We have a generation of polymers that work as a cathode in solid-state batteries. We are now making a second generation, tweaking the original design for higher capacity and performance.

How do you describe why your work is important to non-specialists?

The performance of electric vehicles are still not accessible to most people. They could be cheaper, quicker to charge, and drive further on a single charge. Using polymers in solid-state batteries would allow electric vehicles to run on affordable, safe, high-capacity and well-performing batteries. These improvements will be necessary for the UK government to reach its goal of ending the sale of all petrol and diesel cars by 2030.

How did you get into battery research?

I have always made polymers. My PhD at the University of Bath was in developing sustainable polycarbonates from carbon in sugar. I came to the University of Oxford and worked on bio-based elastomers, which are reusable. Then this project came up, and I heard they wanted a conductive, adhesive material that could accommodate volume changes. My polymers are primarily bio-based and have a lot of oxygen, making them easy to degrade and recycle at their end of life. Oxygen content also happens to be what makes a polymer ionically conductive – lithium ions can hop between the oxygen atoms on the polymer chain. Putting my oxygen-rich, adhesive stretchy polymers in the battery seemed like a good use of these materials. Before working on this specific problem, I knew absolutely nothing about batteries and had to pick up the knowledge quickly.

What is a highlight of your career to date or the aspect that gives you greatest job satisfaction?

I like communicating my work to others and convincing them of the usefulness of polymers in solid-state batteries. Sometimes people are apprehensive about them, especially in SOLBAT, where almost all materials used are inorganic and ceramic. It’s satisfying to make headway here and see more and more people recognise how great polymers could be if applied to solid-state batteries.

What opportunities has being part of the Faraday Institution opened up for you?

I now have a wide connection with other groups and academics across universities, which by extension, also gives me access to kit and equipment I wouldn’t have had otherwise. I lead a package of work and present the results to the Faraday Institution expert panel which includes experts from industry. They provide interesting insight and perspective. Talking to them helps to remind me of our goal: to make better batteries! Involving industry professionals in discussions is not always common in academia, but I think we benefit greatly from doing so.

I also went on a University of Warwick Battery School training course funded by the Faraday Institution that taught me the ins and outs of batteries. It was valuable as a researcher entering this field knowing very little about them.

What are the biggest challenges you have overcome in your career and how have you gone about doing so? 

Oxford is a challenging, competitive environment. It can sometimes put people off taking risks, which is not good for science. Coming into this project as the only polymer chemist involved and not knowing much about batteries was very challenging, and I took a real risk to do it. I had to learn very quickly and do a lot of reading and talking to people to get up to speed with battery research. I also learnt not to take too personally what some people think. I’ve learned to celebrate my own achievements and be proud of the research I do.

What are your career aspirations?

I would like to start my own research group. I’d love to bring more polymer scientists onto the project and maybe get more of the battery being polymer. For example, I think there is real potential for the electrolyte to be a polymer, though there are concerns at the moment that finding a polymer that doesn’t react with lithium metal will be challenging.

What advice would you have liked to have given your younger self starting out on your career?

Don’t overthink it, just do it.

If someone wants to find out more about your research, where would you point them to?

We recently published an article in the Journal of the American Chemical Society on buffering volume change in solid-state battery composite cathodes with block polycarbonate ethers.

I gave a talk on sustainable polymers for the Global Research & Innovation in Plastics Sustainability (GRIPS) 2022 conference:

 

My entry for the University of Bath three minute thesis competition in 2015 is an overview my PhD work on sustainable biopolymers:

 

Connect with Georgina on LinkedIn.

 Published November 2022.

About the author: Cara Burke is the Faraday Institution’s Science Communications Intern in the summer of 2022. She has just completed her BSc Biological Sciences degree at Imperial College London and is pursuing a career in science communications.