High performance Zn–Mn cement batteries for the next generation of buildings

As the buildings and construction sector accounts for 37% of global greenhouse gas emissions, integrating energy storage into building materials offers a transformative pathway toward net-zero infrastructure. However, conventional cement-based structural batteries suffer from low energy density and poor cycling stability due to the presumed electrochemical inertness of cement. Now, researchers from Southeast University and the University of Adelaide, led by Professor Pan Feng, Professor Zaiping Guo, and Professor Changwen Miao, have overturned this perception by developing high-performance Zn–Mn cement batteries featuring active cementitious separators (ACSs).

Why This Technology Matters

Traditional structural energy storage systems treat cement as merely passive electrolyte carriers, resulting in inefficient active material utilization and rapid capacity degradation. The novel ACSs function as capacity boosters rather than inert separators, leveraging the intrinsic alkalinity of cement hydration products to create a dynamic proton-buffering environment that drives unprecedented electrochemical performance.

Innovative Design and Mechanism

The material is engineered through vacuum impregnation of aerated cement mortar with ZnSO₄/MnSO₄ electrolyte. During operation, continuously generated zinc sulfate hydroxide (ZSH) within the cement matrix acts as an effective proton buffer, consuming H⁺ produced during MnO₂ deposition. This buffering prevents local acidification and stabilizes birnessite-MnO₂ formation—overcoming the thermodynamic limitations that typically hinder conventional neutral Zn–Mn batteries.

Outstanding Performance

The ACS-based Zn–Mn batteries achieve a tenfold improvement over existing cement-based systems, delivering 0.92 mWh cm^-2 energy density and 2.30 kWh m^-3 volumetric energy density with exceptional cycling stability (99.98% capacity retention after 1,000 cycles). Simultaneously, the system maintains structural integrity with ~20 MPa compressive strength, successfully powering LEDs while supporting vehicle loads.

Applications and Future Outlook

This work establishes a scalable platform for energy-storing buildings where walls and foundations serve as dual-purpose structural and energy storage elements. For a typical apartment, only 3–7 m³ of this energy storage concrete (2–5 walls) could meet daily electricity demands, compared to 25–75 m³ required by conventional systems—paving the way for truly net-zero carbon buildings.