Origami Batteries have 14 times higher energy density

Arizona researchers suggest that advances in geometric folding algorithms and computational tools to determine folding patterns for making complex 3D structures from planar 2D sheets may lead to numerous other configurations possible for 3D batteries. Furthermore, with advances in robot manipulation including paper folding by robots, the manufacturability of folded batteries at scale may be possible in the near future.

To prepare their batteries, the researchers used carbon nanotube (CNT) coated papers as the current collectors and deposited conventional active material layers (Li4Ti5O12 and LiCoO2) on top of them. They used Laboratory Kimwipes as substrates because the thin and porous nature of the paper allowed the CNT ink to diffuse easily both inside and outside of the paper. This resulted in CNT-coated papers that were conductive on either side.

Polyvinylidene difluoride (PVDF) was used as a binder to improve the CNT adhesion by coating an additional CNT/PVDF layer onto the CNT-coated papers prior to depositing the active materials.

Paper folding techniques are used in order to compact a Li-ion battery and increase its energy per footprint area. Full cells were prepared using Li4Ti5O12 and LiCoO2 powders deposited onto current collectors consisting of paper coated with carbon nanotubes. Folded cells showed higher areal capacities compared to the planar versions with a 5 × 5 cell folded using the Miura-ori pattern displaying a 14 times increase in areal energy density.

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