Integrated energy storage
World’s first cement-bases batteries25th May 2021
Whether it’s just as a back-up for when Eskom throws a wobbly, or whether it’s a serious commitment to using renewable energy, storage is almost always the constraining factor. So incorporating a rechargeable battery in the actual cement structure of a building sounds like a great idea.
Making concrete greener
Concrete is the world’s most commonly used building material but its manufacture and use are very resource-intensive, so many developers are looking for alternative materials. But, perhaps, if concrete were to perform a double – or even triple – function, its sustainability cred would improve immensely.
So here’s some good news. Emma Zhang (currently Senior Development Scientist at Delta of Sweden) and Luping Tang, who worked together Chalmers University of Technology, Sweden, to develop innovative building materials, have succeeded in developing a world-first concept for a rechargeable cement-based battery.
As Zhang says: ‘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.’
Storing energy in cement
The concept is simple. Small amounts of short carbon fibres are added to the cement mix to increase its conductivity and flexibility. And then a metal-coated carbon fibre mesh is embedded within the mixture is a metal-coated carbon fibre mesh. After much experimentation, this is the prototype mesh was created with iron for the anode, and nickel for the cathode.
‘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,’ explains Zhang. ‘This particular idea that we have developed – which is also rechargeable – has never been explored before. Now we have proof of concept at lab scale.
The prototype rechargeable cement-based battery has an average energy density of 7 Watthours per square metre (or 0.8 Watthours per litre). While this is about 10 times the energy density of previous attempts at creating a cement-based battery, the energy density is still very low when compared to commercial batteries. But, of course, there will be no need for space to house, or material to build, these batteries, as they will be part of the structure of the building. And, of course, buildings, bridges and other structures that could be made from this material may be huge, so the storage potential is significant.
Clever, yes, but smart too
The fact that the battery is rechargeable is its most important quality, but there are many other potential applications, ranging from powering LEDs, providing 4G connections in remote areas, or cathodic protection against corrosion in concrete infrastructure to monitoring energy systems.
‘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,’ suggests Zhang.
Challenges and opportunities
The idea is still at a very early stage, and there are technical issues, such as battery life and recyclability, that need to be addressed before the technique can be used commercially. Because, as Zhang says, ‘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. For now, this offers a major challenge from a technical point of view.’
But the researchers are hopeful that their innovation has a lot to offer.
‘We are convinced this concept makes for a great contribution to allowing future building materials to have additional functions such as renewable energy sources,’ concludes Tang.
For more detail, read the full scientific article.