Researchers have 3D-printed a cement-based supercapacitor that can store electricity while still acting as structural concrete. The device uses cement, carbon nanotubes, and carbon black to form interdigitated electrodes printed directly into a cement separator. That design shortens the distance ions travel and avoids the weak interface found in stacked supercapacitors. The result is an areal capacitance of 162.14 mF/cm2, an energy density of 22.52 μWh/cm2, and a compressive strength of 23 MPa, enough for some conventional structural uses. The work points toward buildings that store solar or wind energy in their own concrete, or smaller versions that power embedded sensors and emergency lighting. Performance drops sharply near 0 F, likely due to electrolyte freezing, so durability and cycle life still need work before this moves beyond the lab. For now, it is a useful proof of concept for turning building materials into functional energy storage.
