MIT researchers have made a leap in energy storage by developing a concrete battery which transforms concrete into a functional energy-storing material.
Its latest version of the electron-conducting carbon concrete battery – known as ec3 – can now store 10 times more energy than previous iterations. Made from cement, water, ultra-fine carbon black and electrolytes, ec3 (e-c-cubed) forms a conductive ‘nanonetwork’ that allows structures such as walls and pavements to store and release electricity.
In 2023, storing enough energy to meet the daily needs of the average home would have required about 45 cubic metres of ec3. Now, the team says, with the improved electrolyte, that same task can be achieved by the concrete battery with about five cubic metres. This breakthrough was achieved by refining the electrolyte mix and understanding how the nanocarbon network interacts with it.
“A key to the sustainability of concrete is the development of ‘multifunctional concrete’, which integrates functionalities like this energy storage, self-healing, and carbon sequestration,” says Admir Masic, lead author and EC³ Hub co-director.
Using FIB-SEM tomography, researchers mapped the nanonetwork at unprecedented resolution, revealing a fractal-like web that surrounds ec3 pores. This insight enabled the team to experiment with various electrolytes – including seawater – and streamline the mixing process by adding electrolytes directly to the water.
Organic electrolytes delivered the best performance. A cubic metre of ec3 with quaternary ammonium salts and acetonitrile can store over 2kWh – enough to power a refrigerator for a day. The material has already been used to heat pavement slabs in Japan and could soon support EV charging and off-grid homes.
Image: An electron-conducting carbon concrete (ec³)-based arch structure integrates supercapacitor electrodes for dual functionality. The prototype demonstrates both structural load bearing and the ability to power an LED, with the light’s intensity varying under applied load, highlighting the potential for real-time structural health monitoring via the supercapacitor. Credit: MIT EC³ Hub.
