Researchers developed a concept for rechargeable batteries made of cement. The concept starts with a cement-based mixture with small amounts of short carbon fibers added to increase the conductivity and flexural toughness. Then, embedded within the mixture is a metal-coated carbon fiber mesh — iron for the anode and nickel for the cathode.
The team produced a rechargeable cement-based battery with an average energy density of 7 Watt-hours per square meter (or 0.8 Watt-hours per liter). Energy density is used to express the capacity of the battery and a modest estimate is that the performance of the new battery could be more than 10 times that of earlier attempts at concrete batteries. The energy density is still low in comparison to commercial batteries but this limitation could be overcome thanks to the huge volume at which the battery could be constructed when used in buildings.
The fact that the battery is rechargeable is its most important quality. Energy storage is an obvious application, as is monitoring. The researchers see applications that include powering LEDs, providing 4G connections in remote areas, and cathodic protection against corrosion in concrete infrastructure. It could also be coupled with solar cell panels 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.
The concept of using structures and buildings in this way could be revolutionary because it would offer an alternative solution to the energy crisis by providing a large volume of energy storage. Concrete, which is formed by mixing cement with other ingredients, is the world’s most commonly used building material.
The technology could allow for whole sections of multi-story buildings to be made of functional concrete. Since concrete infrastructure is usually built to last 50 or even 100 years, the batteries would need to be refined to match that lifecycle or to be easier to exchange and recycle when their service life is over.