Imagine if we could combine the strength of a load-bearing structure with the ability to store energy in a single material. In this year's William Chalmers lecture on November 5, “How can multifunctional materials enable massless energy storage?” Leif Asp discusses this concept.
Like the trunk of a tree
In today's electrical systems, such as electric vehicles, hand-held tools, and mobile phones, two separate material systems are used: one for the battery and one for the product itself. This results in unnecessary weight and bulkiness.
"If we instead use a single material, like the trunk of a tree or the skeleton in our bodies, much lighter and slimmer constructions would be possible," says Leif Asp, Professor of Lightweight Composite Materials and Structures at the Department of Industrial and Materials Science at Chalmers. His research focuses on multifunctional composites.
"At Chalmers, we are developing just such materials – a carbon fibre-based multifunctional composite material. The research covers everything from fundamental experimental and theoretical studies on the synthesis, characterisation, and performance of multifunctional materials and structures. The lecture will show how the carbon fibre functions as an electrode, how the stiff and ion-conducting polymer matrix works, and how a battery can be made from a composite laminate – a so-called structural battery."
"There is so much talk about batteries that people think we are developing a new battery, but it is a multifunctional material that is also a battery, with many more functions – just like a Swiss army knife," emphasises Leif Asp.
The William Chalmers lecture is Chalmers' most prestigious and one of the most popular lectures. This year's lecture will be held on Tuesday, 5 November, William Chalmers' birthday. The target audiences are alumni, industry, students, researchers, teachers, and the interested public.
"I will give the lecture in Swedish and am very happy that my parents will come and listen. There are some challenges with complicated physics and chemistry – but I hope it will be a seminar that people can grasp, and I will really strive to make the lecture accessible to many," says Leif Asp.
One of the top ten breakthroughs
The development of structural batteries builds on previous research where it was discovered that certain types of carbon fibre, in addition to being stiff and strong, also have a good ability to store electrical energy chemically. These discoveries were named one of the top ten breakthroughs of the year by the prestigious Physics World in 2018. Leif Asp's research group is world-leading in this research area. He is somewhat surprised that more people have not considered using the structure as a battery. The first attempt was made in 2004 at the Army Research Laboratory in the USA, but they did not succeed. Three years later, in 2007, Leif Asp Asp's research group, then at Swerea SICOMP, now part of RISE, managed to create a functioning structural battery. This sparked further interest. Several projects followed, including collaborations with Volvo Cars and Airbus.
Leif Asp joined Chalmers in 2012. Three years ago, Leif Asp's research group, in collaboration with KTH, demonstrated a structural battery with a carbon fibre anode. The multifunctional performance of the structural battery was ten times higher than other structural batteries at that time.
In September this year, Leif Asp's research group presented a major breakthrough in so-called massless energy storage – an all-carbon fibre-based structural battery. Here, the cathode is also based on carbon fibres, making the stiffness much higher than before.
"This has been our targeted material design all along, it took many years, and since 2007 we have presented several results. Now we will work further on the energy density, which is now 30 Wh/kg, to double it in the material. Then we will focus on increasing the power. This will be important for broader applications, such as running entertainment systems, etc., in aeroplanes,” says Leif Asp.
"It is a structural parasite"
Before Tesla became popular, there was a sports car, the Tesla Roadster. Leif explains and shows a picture of the car, battery, chassis and body. In the vehicle, there was a battery pack that weighed 450 kilos – and without any structural capability:
"It is a structural parasite. We need extra material in the body to carry that load, otherwise, it won't hold. It gives no structural efficiency contribution at all. Electrically, the energy contribution is 100 percent, but the total weight of the chassis and body in this car is 780 kilos, which only has structural capability but no electrical storage capability at all," says Leif Asp. If you instead integrate structural capability into the battery, or energy storage capability into the body, you can save a lot of weight. This is very beneficial. It reduces both the amount of used materials and the energy consumption in service."
A tremendous amount of research coming in this direction
Leif Asp has previously stated that the next generation of structural batteries has great potential and that it is fully possible to manufacture laptops, smartphones, or electric bicycles that weigh half as much as today and are much more compact within a few years. In the longer term, one can imagine electric cars, electric aeroplanes, and satellites being constructed and powered by structural batteries. But this requires much higher power output from the structural battery than we can achieve today.
"But we and KTH cannot drive this alone. What is happening now is that there is a tremendous amount of research coming in this direction. In 2016, there were a total of about 100 publications worldwide in the field of structural energy storage materials. Now there are 500 per year. At least. There are groups in Asia, Europe, Australia, and the USA. Everywhere. And there are slightly different approaches," says Leif Asp.
Finally, what do you think will attract people to the lecture?
"Our research has received a lot of attention, so quite a few people have an idea of how it works through TV, radio, and newspapers. I think the title of my lecture, "How can multifunctional materials enable weightless energy storage?" can attract many. People want answers to that."
Welcome to the lecture
The William Chalmers Lecture 2023 is held in Swedish and takes place on 5 November at 18 – 19:00 in Runan, Chalmers Kårhus. Register no later than 3 November.
