Erik Nijkamp and Paul Volčokas

Erik Nijkamp and Paul Volčokas from TU/e’s Team Better/e aim to pave the way for ecofriendly, cost-effective batteries able to power entire cities in times of insufficient supply of renewable energy.

The fact that the current generation of TU/e students more than ever is driven by societal challenges, is well-illustrated by the tens of student teams the university harbors. Even disastrous events like the COVID-19 pandemic cannot stop these young, smart, and passionate people from chasing their dreams to make a difference. Erik Nijkamp and Paul Volčokas from Team Better/e, a student team that started in the midst of the pandemic, share their plans and ambitions.

‘In 2020, during corona, I joined the Honors Academy,’ says Nijkamp, who is currently in the master phase of his Chemical Engineering education. ‘I immediately knew that I didn’t want to join an existing team, but that I wanted to develop my own project. After extensive talks with staff members I decided to look into the potential of liquid metal batteries.’ Together with two other students, he founded Team Better/e.
‘When in my second year as a Mechanical Engineering student, I was presented with the idea of the liquid metal battery. Since the combination of fluid flows and heat management intrigued me, I decided to join the team,’ Volčokas adds.

Making a switch
After an extensive research phase that lasted about a year, the team decided to discard its initial idea of working on liquid metal batteries. This is a battery that take normally solid metals such as Tin and Calcium, and heating them up to 600 degrees Celsius so that they become liquid. This allows for the metal atoms to become ions, releasing electrons which can be collected to produce energy. These ions can be converted back to a neutral metal when charging, making a high efficiency, rechargeable battery.  Nijkamp: ‘On paper, that idea looks great. It should be super cheap and efficient. And since the design doesn’t rely on membranes, in theory, such a battery could last forever.’ But, as is so often the case, practice turned out to be more complicated. ‘Liquid metals are hot. And to prevent the metal from rusting, the environment has to be completely free of oxygen. Such a device is way too hard for students to fabricate.’ Volčokas: ‘We understood that at university we both lack the required skills and permits to conduct the necessary experiments on liquid metals. So we decided to switch to redox flow batteries. This is a technology that already exists in the lab. And in China, a specific type of redox flow batteries is produced at a commercial scale already, though not yet for grid-sized applications.’ This first generation of commercially available redox flow batteries is based on vanadium, which is a rare earth metal. Team Better/e explicitly aims to develop a more ecofriendly and cost effective alternative based on the abundantly available iron.

On paper, the working mechanism of their battery is rather straightforward: A redox flow battery consists of two tanks, a positive tank and a negative tank, separated by a core where chemical reactions take place. The positive tank contains FeCl₂, and the negative tank contains FeCl₃. Two reactions occur in the core. While discharging, Fe is converted to Fe(2+), which means electrons will be released. On the other side, Fe(3+) is converted to Fe(2+), which will use electrons. While charging, both reactions go in the opposite direction. The size of the tanks is directly proportional to how long you will be able to power your home or factory. And the size of the core is directly proportional to the number of homes or factories the battery can support.

Up until recently, due to problems with the required membranes, redox flow batteries only were considered a realistic probability for small scale applications. But over the past years, membrane technology has significantly improved, for example with Antoni Forner-Cuenca's research. Nijkamp: ‘We are convinced that redox flow battery technology can be made ready for large scale applications as well. We want to accelerate this development, by making everything we do available open source.’

Two teams to tackle problems
Nijkamp: ‘We started by trying to reproduce a design from a paper. But that didn’t work at all.’ Volčokas: ‘We got confronted with massive leakages, since the original design used clamps instead of bolts. So we have been working on a new design for the housing, which we are currently testing for leakages.’ Within Better/e, two teams have been established, both students explain: one team is focused on the physics of the cell housing, and the second team is working on the chemistry. Nijkamp: ‘One of the chemical challenges we will have to tackle is how to fight the hydrogen evolution reaction that occurs when the pH is too low and hydrogen gas is formed. Another problem we have to solve, is that sometimes solid iron is formed, which forms dust and leads to slurry in our tanks.’ ‘What’s worse, that solid iron can form dendrites, which puncture our membrane and cause safety issues,’ Volčokas adds.

The first aim of the team is to demonstrate that their idea works on a single cell level. Volčokas: ‘When we’ve achieved that, we will build a small-scale demonstrator for Eindhoven Airport, with whom we have a partnership, to show the public what we are working on. And then the next step is to develop our single cell into a stack of cells.’ Nijkamp: ‘I like to dream big. It would be great if eventually Team Better/e could build a battery that can power a building on campus.’

Open innovation
All in all, the students still have a lot of technological challenges to overcome. But they are optimistic. ‘We get a lot of help here at university, especially from Antoni Forner-Cuenca and his group. The Honors Academy has also been a great help, as well as our coaches, Yali Tang and Mark Cox. EIRES has also been one of our biggest supporters. Whether it's giving us a meeting space or sending us to Denmark, EIRES has always been helping us. And we work closely with the FAIR battery project, which is led by Sanli Faez from Utrecht University, and Antoni Forner-Cuenca and Yali Tang from TU/e are involved. Additional to financial support from this project team, they shared all of their information with us, up until the electronic specifications and the blueprint of their design.’ It is this open innovation attitude both students are also advocating themselves. ‘We do not want to make a profit out of this, but we want to lower the barrier for entry by advancing this technology to such a level that others are interested to step in and take over.’   

To achieve this ambition, new members are more than welcome to join the team, both students emphasize. Volčokas: ‘By the end of this academic year, some of the current team members will leave the team. So we can certainly use some new people. There are lots of challenges that still need to be tackled, for example when it comes to powering the stack.’ ‘And if any staff members can help us in gaining access to the high quality materials we need, that would be most welcome too,’ Nijkamp adds.

For both students, so far the experience of being part of Better/e has been a very joyful and fruitful one. Volčokas: ‘The goal of the Honors Academy is to grow beyond the curriculum and gain new kills. Over the past year we have entered in multiple contests and competitions, where we had to present our ideas to huge crowds and some important people such as the Dean of the Department Mechanical Engineering, the jury of TU/e Contest. That requires skills I would have never gained otherwise.’ Nijkamp concludes: ‘My goal in life is to leave things better than I found them. It would be great if we could end up with a result that other people can build on to make large-scale battery storage a reality.’