Almost four years ago, this blog reported on Dr. Yi Cui’s “painted battery,” a method of coating even paper with carbon nanotubes and silver nanowires, with the coated paper being able to store energy. Adding origami to the concept, Arizona State University researchers have folded a paper-based lithium-ion battery and managed to demonstrate a 14-fold increase in areal energy, or energy density per unit of area. This has serious implications for batteries that can be printed on roll paper and which have the requisite flexibility. More rigid batteries might crack under the strain, for instance, and achieve negative results from being folded. “’Foldable batteries may be useful for powering devices that have limited space on board,’ coauthor Candace Chan, Assistant Professor of Materials Science and Engineering at Arizona State University told Phys.org. “’Furthermore, with the development of foldable paper-based electronics demonstrated by other research groups recently, a battery that also can be folded may become important for integration of the …