Could the solution to the impending battery crunch be… origami? Scientists at Arizona State University have created a lithium-ion battery out of carbon nanotube-coated paper — and then, by folding it like a map, they have increased the battery’s energy density by 14 times.
We should probably start with the fact that this foldable lithium-ion battery is made out of paper. As you’ve probably surmised, it’s not possible to bend a conventional lithium battery, because it has numerous rigid parts (the carbon anode, the protective casing). To create a paper-based battery, the scientists started with a KimWipe (a porous lint-free paper towel), coated it with polyvinylidene difluoride (PVDF) to improve adhesion of carbon nanotubes — and then dunked the PVDF-coated paper into a solution of carbon nanotubes (CNTs). Powders of lithium titanate oxide (LTO) and lithium cobalt oxide (LCO) — standard lithium battery electrodes — are sandwiched between two sheets of CNT-imbued paper. Thin foils of copper and aluminium placed above and below the sheets of paper complete the battery.
Using the Miura fold, the scientists took a 6×7-centimeter (42 cm2) lithium-ion paper battery, and kept folding it until it had a surface area of just 1.68 cm2. While this is a size reduction of around 25 times, the energy density was only increased by 14 times, due to losses from the folding process. The folded paper battery has an areal energy capacity of around 2.0 mAh/cm2, which drops off fairly quickly to 1.5 mAh/cm2 after a few charge/discharge cycles, but keeps its charge fairly well after that.
The scientists will now look at ways of folding the paper even more efficiently, further increasing energy density. Folded paper batteries might eventually be very useful for powering foldable devices — imagine a foldable e-ink or OLED display, powered by a foldable battery, that can be stashed away in your pocket when you don’t need it.
Thanks to: http://hipknowsys.blogspot.com