Multifunctional Cement–Mine Tailing Composites for Energy Storage

ABSTRACT

Cement‐based supercapacitors offer a path to sustainable, multifunctional infrastructure but typically suffer from a trade‐off between mechanical robustness and ion transport. Here, we investigate how hydration‐driven pore evolution and copper mine tailing (CMT) incorporation govern this balance in cementitious composite electrodes. Structural energy‐storage composites were prepared from Ordinary Portland Cement and industrial mining waste, utilizing the natural porosity of cement paste while converting discarded mining waste into functional fillers that enhance interfacial polarization. A two‐part investigation was conducted to optimize the pore network via water‐to‐cement (w/c) ratio and enhance storage capability via CMT dosage (0.5–10 wt%). By identifying 0.6 as the optimal w/c ratio using 5 wt% CMT and then optimizing CMT content at that ratio, we found that both 2.5 and 5 wt% CMT yield comparable 28‐day areal capacitance of 6.9 mF/cm ² , while the 5 wt% CMT composite achieved a high compressive strength of 44.9 ± 3.0 MPa. Together, these results demonstrate that tailoring the mix design offers a direct method to adjust mechanics–transport trade‐offs in cement composites, demonstrating their viability as sustainable, energy‐storing structural materials.