Red bricks: A breakthrough battery for renewables?

Source: By Miranda Willson, E&E News reporter • Posted: Thursday, August 13, 2020

An age-old, universal building material that might already exist in your home could one day be used to store energy, according to a new study.

Researchers at Washington University in St. Louis have come up with a way to retrofit wood-fired red bricks so that they are capable of storing 3 watts of electricity — enough to power a lighting device for 50 minutes, said Julio D’Arcy, corresponding author of the study.

The bricks, which could be scaled up for widespread use at a reasonable price, would amass energy from residential solar panels or other renewable energy sources that require storage during intermittent times, D’Arcy said. The energy could remain in the bricks for three days.

“We’re adding a green functionality to homes,” said D’Arcy, an assistant professor of chemistry at Washington University who worked on the study with graduate student Hongmin Wang.

To develop the technology, the researchers placed a plastic material known as a poly(3,4-ethylenedioxythiophene) polymer inside the bricks. Tiny fibers made of the polymer penetrate the entire brick and ultimately increase its surface area, which then increases the amount of energy that can be stored to make the brick an efficient storage device, D’Arcy said.

The chemical composition and structure of the bricks are key to the technology, researchers said. The bricks’ pigment — which is red due to the presence of iron — ignites a chemical reaction that forms the polymer, D’Arcy said.

Two bricks — one with a positive charge, and one with a negative charge — make up the “battery,” which the researchers refer to as a supercapacitor. The complementary bricks act in a fashion similar to the positive and negative charges of batteries, D’Arcy explained.

“Once we have the nanofibers on the bricks, you put two bricks together, and by assembling two bricks together, you start to build something like a battery,” he said.

In addition to providing electricity for lights, the supercapacitor bricks could be ideal for powering small electronic devices and appliances, according to D’Arcy. They take 13 minutes to charge and can be recharged up to 10,000 times, he said.

Published yesterday in Nature Communications, the study is groundbreaking in that it paves the way for architects to incorporate energy storage technologies into the design of homes and buildings using a cheap construction material, D’Arcy said. While the supercapacitor bricks are not suited for use in the foundation of a house or as construction materials bearing intense weight, they could be placed in or along the walls of homes for decoration, D’Arcy said.

“You could stack them in any fashion you want. You could stack the bricks close to an outlet, or a light source,” he said.

‘Very transformative’

Developing cost-effective and widespread energy storage technologies is crucial for the accelerated deployment of renewable energy, experts say.

Lithium-ion batteries are the most commonly used material for storing solar energy, according to the Solar Energy Industries Association. While the batteries have become less expensive in recent years, battery costs remain a barrier to achieving long-term renewable energy storage, said Wale Odukomaiya, a research engineer with the National Renewable Energy Laboratory.

The brick supercapacitors developed in this study appear to offer a new way to store energy in buildings, said Odukomaiya, who was not involved in the research.

“Energy storage is one of the most important enabling technologies for renewable energy sources,” he said. “Buildings are going to play an important role in that, so something like this is very interesting.”

While the supercapacitor bricks cannot store as much energy as lithium-ion batteries, the researchers intend to increase the storage capacity of the bricks in order for them to be more efficient and cost-effective, D’Arcy said. After that, they will work to scale up the process of building the bricks, he said.

“It’s the beginning of a proof of concept, and it demonstrates that, yeah, we can convert a house into an energy storage device,” he said.

Even though it is known that red bricks themselves are “dirt cheap,” the study does not detail the full costs of the supercapacitors, Odukomaiya said. Quantifying and minimizing the costs of constructing the supercapacitors as well as determining how to integrate the bricks into electrical systems in buildings may be important next steps in the research, he said.

Nonetheless, the study introduces what appears to be a new concept — using cheap, functional and ubiquitous materials for energy storage, said Anthony Shoji Hall, an assistant professor of material science and engineering at Johns Hopkins University who was not involved in the study.

“I think integrating supercapacitors into materials used in everyday life is potentially very transformative,” Hall said.