Mobile devices like laptops, cellular phones and other devices - powered by a new generation of lithium-ion based batteries - have changed our lives, according to Professor Silvia Bodoardo of the Politecnico di Torino, Italy. Likewise, electric vehicles (or EVs) powered by larger versions of these batteries could transform our cities - reducing petrol consumption and emissions of carbon dioxide and toxic air pollutants.
High energy density lithium-ion batteries are, for now, the best technology available. But the technology is not ideal because of the weight, high cost and limited capacity. Research efforts are now focusing on new technologies like lithium air batteries that could offer a solution.
The focus of the STABLE project was on lithium-based cells for EVs, which will have a very important economic impact. Lithium-air batteries will also be well suited to renewables for energy storage. This type of system is high energy but not high power – and this is the difference. High power batteries can store energy during peaks of production and retain it for future use when generation is low.
But the problem with all lithium-based cells is degradation. Our lithium-air cells consist of a metallic lithium anode and a conductive porous membrane carbon-based (and Ni) cathode with a catalyst that helps oxygen from the air react with lithium ions. Moisture in the air is a big problem because it reacts with lithium. So we try to protect the metallic lithium anode rather than sealing the whole cell. Our idea was to use starchy compounds known as cyclodextrins – which contain many OH- groups – to block water while letting through oxygen.
We are now working on lithium-sulphur cells too, which also have many challenges to overcome, although potentially much closer to the market. Like lithium-air cells, the problem is also the anode! We are working on a ceramic membrane to protect the anode and looking for alternative anode materials like silicon. Another problem is the solubility of sulphur in the electrolyte, which we are hoping to solve by using new cathode materials as protective cages around sulphur particles. This technology could be the future because the energy density is five times that of lithium-ion cells.
The market for lithium-ion cells for EVs has also grown very quickly. EVs are now a reality in many places. Norway, for example, is pushing very hard on this technology; there are many EVs in the Netherlands; and the first charging point for EVs has even reached Torino!
But Europe, I feel, has lost the competition on lithium-ion cells: 95% of these batteries are now produced in Asia. It would be very difficult to catch up, but we still have the chance to compete on niche batteries or new lithium-air/ lithium-sulphur technologies. I think companies will invest in developing a technology that is close to market because they can see the economic potential. But companies will not fund technologies that are quite far from the market like lithium-air cells. If we can establish an entire value chain from production to energy storage to the recycling and reuse of cells in Europe, it could be possible to compete.
But let’s also think about emerging countries where there is little or no cabling or infrastructure. If you could store energy in a battery, you could provide light in a school in the middle of nowhere, up a mountain, in a desert or wherever. Batteries could offer a democratic way of providing energy to everyone. The challenge is to reduce the cost.
We now have to focus on the future and learn from history and our mistakes.
With STABLE, our aim was to achieve a lithium-air cell with 2000 mA/h capacity over 100-150 cycles. As well as developing a membrane that protects the anode from moisture, the cyclability of the cells was also a big challenge. I remember well that after the first six months of the project, our cells were not reversible at all! It was a significant problem to overcome but by the end of the project, we reached 151 cycles. It was a record for this kind of system! We were very lucky to find the right solution.
Now that the project has completed, we are working with companies and hope in the future to use our results to produce new electrochemical systems. I think that our project can achieve its objective of giving Europe some expertise in this area.
The first year of the STABLE project was very hard but then we saw light at the end of the tunnel. When we reached our objectives – it was incredible!
I am part of the Electrochemistry group at the Politecnico di Torino. We have focused on batteries for several years, particularly lithium-based batteries, and more recently electrochromic devices. We started with a national project in lithium-air systems many years ago. The, four years ago, we started the STABLE project, which at that time was one of the first steps exploring lithium-air batteries. We thought if we could get a system with an energy density close to liquid fuels, we could really compete! Although the energy density of lithium-air systems today is about a fifth of their theoretical value, it is not so very different from the energy density of liquid fuels, which lose around 80% through waste heat. The problems we face now are related to the industrialization of the system.
I think it is quite difficult to coordinate a project without any experience of European projects, because it is a very different way of managing research. You need to match everybody’s interests so you can reach your objectives. For example, research centres want to publish results, but companies generally don’t. So you have to organize the project so that some results can be published and some can be exclusive to participating companies. It is a kind of balancing act!
If you are alone you have only two hands, but if you are many you have many hands. When you start seeing results in a project, all the partners start working much more quickly. It is exciting when everyone is pushing in the same direction!
Thanks to these activities at the European level, many younger researchers are now coming to work with me. I also always push my PhD students to spend some period abroad, which is much easier if you are involved in EU projects. It is very positive because even a young student takes something useful and brings back something new.
Overall, there are two main benefits: the generation of new knowledge and personal relationships between researchers. It is like a family – by the end of the STABLE project we had a marriage, and three or four babies! Through these projects you make friends for life.
I always say start with an idea – it is really important to have a strong idea on which can be built on several activities. The next step is to consider which partners would fit with the project. It can help if you already know your potential partners – that they will work well together to get results. The consortium is the most important way to be certain of having a successful project. It was very easy with the STABLE project because the consortium was small – only seven partners. It is much more difficult with a large number of partners. Everybody should feel that the work will be helpful to them and society.
Then you have to be lucky!
It is always hard work! But in the end, I learned so much. I would recommend participating in European projects first and joining a partnership. Go to workshops, try to understand how to write a proposal by taking part in evaluations – you can find out what the European Commission is looking for. Then you have to be courageous and brave enough to jump into the deep end!