New research from Sweden’s Chalmers University of Technology is opening the way for concrete buildings to store energy like a giant battery.
The research, which is in the proof of concept phase, involves a cement-based mixture, with small amounts of short carbon fibres added to increase the conductivity and flexural toughness. Then, embedded within the mixture is a metal-coated carbon fibre mesh – iron for the anode, and nickel for the cathode.
With this combination, the researchers have produced a lab-scale rechargeable cement-based battery with an average energy density of 7Wh/m2 (or 0.8Wh/l). While this energy density is low in comparison to commercial batteries, it is more than ten times that of earlier attempts at concrete batteries and is a limitation that could be overcome thanks to the huge volume at which the battery could be constructed when used in buildings.
Another quality, in which again the concept exceeds earlier concrete batteries, is that the battery is rechargeable, thus expanding the possibilities for utilisation once developed further and commercialised.
Potential applications envisaged range from powering LEDs, providing 4G connections in remote areas or cathodic protection against corrosion in concrete infrastructure.
It could also be coupled with solar cell panels for example, to provide electricity and become the energy source for monitoring systems in highways or bridges, where sensors operated by a concrete battery could detect cracking or corrosion.
“Results from earlier studies investigating concrete battery technology showed very low performance, so we realised we had to think out of the box, to come up with another way to produce the electrode. This particular idea that we have has never been explored before,” says building technology researcher Emma Zhang, now Senior Development Scientist at Delta of Sweden.
“We have a vision that in the future this technology could allow for whole sections of multi-storey buildings made of functional concrete. Considering that any concrete surface could have a layer of this electrode embedded, we are talking about enormous volumes of functional concrete.”
There is still a lot of work to do with the concept, particularly around the service-life aspects. Technical questions remaining to be solved include extending the service life of the battery and the development of recycling techniques.
Since concrete infrastructure is usually built to last fifty or even a hundred years, the batteries would need to be refined to match this or to be easier to exchange and recycle when their service life is over.