By folding a paper-based Li-ion battery in a Miura-ori pattern (similar to how some maps are folded), scientists have shown that the battery exhibits a 14x increase in areal energy density and capacity due to its smaller footprint. Paper-based batteries are already attractive due to their low cost, roll-to-roll fabrication methods, and flexibility. The advantages of folding them into smaller sizes adds to these features and could lead to high-performance batteries for various applications.
The researchers, Qian Cheng, et al., from Arizona State University, have published a paper on folding paper-based Li-ion batteries in a recent issue of Nano Letters.
"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 power source and other components into a single, entirely foldable device."
In the current study, the scientists used Li-ion batteries made of carbon nanotube (CNT) ink as the current collectors; conventional lithium-based powders as the electrodes; and thin, porous KimwipesTM as the paper substrates. The researchers also added a polyvinylidene difluoride (PVDF) coating to improve adhesion of the CNT ink to the paper substrates. The final batteries showed good conductivity and—after an irreversible capacity loss after the first cycle—a relatively stable capacity.