Breakthrough cement battery turns buildings into rechargeable power banks

Researchers in France and Spain have designed a groundbreaking cement-like material that not only supports structural loads but also functions as a rechargeable battery.

The team consisting of scientists from the University of Bordeaux and the University of Basque Country, believes this innovative device could pave the way for a new generation of energy-storing buildings, where walls themselves help store and deliver power.

Led by Vadim M. Kovrugin, PhD, an assistant professor specializing in energy storage, the study focused on transforming metakaolin – an amorphous, synthetic aluminosilicate produced by heating kaolinite clay – into functional energy-storing material.

When mixed with a carefully formulated activating solution, this highly reactive substance formed a durable geopolymer paste, which, once embedded with zinc (Zn) and manganese dioxide (MnO₂) electrodes, becomes a high-performance solid-state battery.

The potential of built-in energy

The system delivered an impressive energy storage capacity of around 3.3 watt-hours per liter, marking a significant step forward in integrating power systems directly into construction materials.

Kovrugin emphasized that the innovation goes beyond conventional battery design . "This is more than a battery," he said. "It is a new material concept, where infrastructure does not merely stand still but can actively contribute to the energy ecosystem."

Unlike traditional Portland cement – the main component of concrete – which has been explored for heat storage and leads to high carbon emissions during production, the geopolymer approach is more sustainable. It additionally enables electrochemical rather than thermal energy storage, making it significantly more efficient.

Meanwhile, the metakaolin-based matrix, which boasts a mildly acidic environment, overcomes a key limitation of earlier cement-based batteries by preventing unwanted chemical reactions that hinder rechargeability.

While traditional alkaline systems form insoluble compounds like calcium zincate, reducing rechargeability, the new design preserves zinc in its ionic state, ultimately boosting efficiency through reversible plating and stripping. This is exactly what allows the system to be fully rechargeable.

However, according to the researchers, hydrogen evolution still remains a major challenge, as it leads to the formation of hexahydrated zinc sulfate, damaging the electrode–electrolyte interface and eventually cracking the geopolymer, compromising long-term performance.

Architecture meets energy

In a bid to address this, the researchers proposed a modular design that embeds battery components in layered or compartmentalized sections, thus allowing for easier maintenance and replacement without compromising the structural integrity of the material.

Meanwhile, significant water loss observed after 40 days of curing highlighted the importance of managing hydration and drying behavior, factors crucial to the durability of the geopolymer material . This dehydration led to a noticeable drop in electrochemical stability, suggesting that hydration levels are highly important for maintaining sufficient conductivity.

However, since raising the water content may potentially compromise the material's mechanical strength , both the geopolymer composition and curing process will require further optimization, to make the material more viable for real-world applications.

"Despite challenges, our findings highlight the potential for integrating energy storage into building materials, paving the way for sustainable infrastructure development," the research team concluded.

The study has been published in the journal Materials Horizons .