A team from the Harbin Institute of Technology and the Chinese Academy of Sciences has 3D printed a supercapacitor straight into a cement-based structure. The study, by Haiping Wu, Jing Zhong and Wencai Ren, was published in ACS Nano. The two electrodes are printed as interlocking fingers inside the cement, so ions only have a short gap to cross.
The conductive ink mixes cement with carbon black and carbon nanotubes. The device reached an areal capacitance of about 162 mF/cm² and an energy density of about 22.5 µWh/cm², while the element kept a compressive strength of 23 MPa, comparable to commercial concrete. Three linked devices were enough to light LEDs, but performance dropped sharply at −18 °C, as the water and ions inside began to freeze.
Why it matters to us: it is still lab work, far from a finished product. But it shows that a printed concrete element can carry more than load and form, and that the material itself is still being reinvented. That is exactly the kind of material innovation we keep an eye on for future pieces.