Could Concrete Batteries Become the New Building Blocks and Power Source of Cities?

With the rise in construction activity fueled by rapid urbanization and population growth, engineers, researchers, and scientists are considering how advanced building materials can result in infrastructures that are stronger and more sustainable. Advanced materials demonstrate exceptional properties that can make buildings both energy-efficient and resilient. Many researchers have focused on materials with smart features such as self-powering and self-sensing for structural health monitoring applications.

Rechargeable cement-based batteries utilized as functional concrete. Illustration courtesy of Yen Strandqvist.

Contributing to research surrounding the ever-growing need for sustainable materials, a team at Chalmers University has set out to develop the “world's first” rechargeable cement-based batteries. In their research, Dr. Emma  Zhang and Professor Luping Tang of Chalmers University and their team created a rechargeable cement-based battery and recently shared their work in a research article.

The battery has an average density of 7Wh/m2 or 0.8 Wh/L recorded during six charge/discharge cycles. To improve the conductivity of the cement-based electrolytes, the modification was done by adding short carbon fibers (CF) to the electrolytes. The research involved much experimentation, and the current prototype uses iron (Fe) and zinc (Zn) as anodes and Nickel (Ni) oxides as cathodes.

“Results from earlier studies investigating concrete battery technology showed very low performance, so we realized we had to think out of the box, to come up with another way to produce the electrode. 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,” Zhang said.

Various distinct combinations of cells were tested as a part of this research. The results showed that the rechargeable cement-based electrodes with iron powder and Ni(OH)2 can make a mini-LED lamp shine for several hours, and its energy density is 0.5Wh/m2. The electrodes with a coating of Ni and Fe performed much better. The maximum energy density of 7Wh/m2 was recorded with these electrodes during six charge/discharge cycles.

Chalmers University's news article shares that the energy density of this new battery technology is still low in comparison to commercial batteries. However, large-scale production of the batteries could potentially outweigh that factor.

Cement-based and Rechargeable

Batteries consist of three main components: an anode, a cathode, an electrolyte, and a separator to prevent the anode and cathode from touching. The researchers used the layered structure of the battery, and for making the electrodes, performed the process of electroplating metals onto carbon fiber (CF) meshes. Then the metal-coated CF meshes were then cast in a conductive mortar. For the cement-based separator, researchers added ion exchange resin which is commercially available to the cement mortar to increase the ionic conductivity of hydroxide ions and provide high electrical resistivity to the cement-based electrolyte separator.

A single-cell cement-based structural battery. A multimeter shows the cell potential of 1.24V after a 3-hour discharge. Image courtesy of MDPI, Emma Zhang and Luping Tang (CC BY 4.0)

For a battery to be rechargeable, an appropriate choice of electrode materials is necessary such that the chemical reaction that occurs during the discharge process can reverse. Therefore, the researchers considered iron and zinc for anode as they undergo reduction during charging and oxidation during discharging. For the cathode, nickel is preferred because it undergoes an oxidation reaction during charging and turns into nickel oxide hydroxide and nickel oxide under alkaline environments; plus, nickel undergoes a reduction reaction during discharging.

Utilizing a Cement-Based Battery

The researchers see applications in monitoring systems, providing 4G connection in remote areas, providing protection against corrosion in a concrete infrastructure, and many others. 

Concrete is the world's most commonly used construction material. And with a rechargeable battery, it can collect and store renewable energy such as solar or wind energy. Due to large volumes, the energy storage capacity can be high.

"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,” Zhang said.

The researchers are hopeful that their research can make a significant contribution to the development of future building materials. However, there are technical queries that need to be confronted, like increasing the service life of the battery and the development of recycling techniques.

About the researchers

Dr. Emma Zhang is currently a Senior Development Scientist at Delta of Sweden and formerly of the Department of Architecture and Civil Engineering, Chalmers University of Technology. 

Professor Luping Tang is a professor at the Department of Architecture and Civil Engineering and supervises the research group Building Materials at the Chalmers University of Technology. His research works are based on cementitious materials and products, with a focus on the durability of materials.