A Battery in the Walls: Geopolymer-Based Energy Storage for Tomorrow’s Buildings
What if the walls of our homes could store electricity? That’s the vision of a research team from the Institute of Condensed Matter Chemistry of Bordeaux (ICMCB/CNRS – University of Bordeaux – Bordeaux INP), working with the Centro de Física de Materiales (CFM) CSIC – UPV/EHU in the framework of the cross-border cooperation network LTC (Laboratoires Transfrontaliers de Coopération) on the Euskampus/Bordeaux Campus. Their goal: to develop a new electrochemical energy storage technology based on geopolymers, paving the way for direct integration of energy storage capabilities into construction materials
As renewable energy sources continue to grow – often with intermittent output – the need for efficient, stationary storage solutions becomes increasingly urgent. While the idea of using cement to store energy has been around for decades, it has long remained marginal due to poor performance, mainly limited to thermal storage. Drawing inspiration from geopolymers – already used in low-carbon concrete – the research team has developed an electrochemical system that directly converts chemical energy into electricity, with significantly improved efficiency. The concept could, for example, allow electricity generated by rooftop solar panels to be stored directly within a building’s walls and used later when needed.
In this context, the researchers of the ICMCB and CFM have taken a major step forward by designing a geopolymer battery embedded within structural materials. Their system combines two well-known electrodes: zinc as the negative electrode and manganese dioxide as the positive electrode. The entire device is embedded in a solid aluminosilicate matrix – typically used as a binder in construction. Instead of conventional ordinary Portland cement, the researchers opted for a metakaolin-based geopolymer, a mineral binder known for its excellent mechanical and environmental properties. Activated here by a zinc sulfate solution, the matrix retains a residual liquid phase in its pores, enabling ion transport essential for battery operation. The result is an energy density of 3.3 Wh/L – four times higher than previous ordinary Portland cement-based systems (0.8 Wh/L). While this is still far lower than conventional batteries such as Li-ion (~570 Wh/L), Ni-MH (~235 Wh/L), or lead-acid (~70 Wh/L), energy density is less critical here since the storage medium is integrated directly into the large volume of the building structure.
Still at an early proof-of-concept stage, several technical challenges remain: improving zinc electrode stability, enhancing the mechanical properties of the solid geopolymer electrolyte and others… But these hurdles appear surmountable, given recent progress in Zn-ion aqueous battery technology and the growing adoption of geopolymers in the construction sector.
Published in Materials Horizons, this innovative concept could one day contribute to the development of positive-energy buildings – where the walls themselves help store electricity. A promising step toward a more resilient, sustainable, and low-carbon built environment.
Reference :
Vadim M. Kovrugin, Liliane Guerlou-Demourgues, Laurence Croguennec, Jorge S. Dolado & Cyril Aymonier
A sustainable approach to energy storage in buildings: the first rechargeable geopolymer-based battery
Published 4th April 2025
Materials Horizons 2025
A Zn-MnO2 electrochemical system is integrated into a solid, metakaolin‑based geopolymer matrix. This architecture enables energy to be stored and released directly from the construction material, paving the way for buildings that can store electricity within their walls.