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According to a recent report from Phys.org, an American research team has made a breakthrough in energy storage by using origami-inspired folding techniques on paper-based lithium-ion batteries. Their findings show that the energy density and capacity per unit area can be increased by as much as 14 times through a method called Miura-ori folding.
This innovative approach was detailed in a study published in the journal *Nano Letters* by researchers from Arizona State University, including Qian Cheng and her colleagues. The team explored how folding paper-based batteries could revolutionize the design of compact, flexible power sources for next-generation electronics.
Candace Chan, an assistant professor at Arizona State University and co-author of the study, explained that foldable batteries could be especially useful for devices with limited space, such as wearable technology or portable gadgets. She emphasized the importance of integrating power sources with other components into a single, fully foldable device, making the development of a foldable battery pack a key goal in the field.
The researchers used carbon nanotube (CNT) inks as current collectors, traditional lithium powders as electrodes, and Kimwipes as paper substrates. To enhance adhesion, they applied a polyvinylidene fluoride (PVDF) coating. This combination resulted in a battery with good electrical conductivity and stable performance, even after repeated folding.
They tested two folding methods: a simple half-fold and the more complex Miura-ori technique. While the half-fold increased energy density by up to 10.6 times when folded three times, the Miura-ori method proved far more efficient. A 6 cm by 7 cm battery folded into 25 layers achieved a 14-fold increase in energy density and reduced its total area to just 1.68 square centimeters.
"We measure energy density per unit area rather than per unit weight because the mass remains constant during folding," explained Chen. "This allows us to better understand how folding affects performance without complicating the comparison."
Although the basic electrochemical properties of the folded battery were similar to those of a flat cell, the coulombic efficiency was slightly higher, likely due to improved contact between the electrode material and the carbon nanotubes after folding.
However, the Miura-ori method did result in some minor performance losses, such as reduced discharge capacity and permittivity. These issues were attributed to delamination at the fold intersections, which the team addressed by inserting a flexible insulating layer of Parylene-C between the layers.
This research marks a significant step forward in the development of high-density, foldable energy storage systems. With advancements in geometric folding algorithms, computational modeling, and robotic assembly, more complex and scalable designs could soon become a reality.
Thanks to their low cost, ease of manufacturing, and flexibility, paper-based batteries have already attracted considerable attention. If folding techniques can further boost their performance, this could lead to the creation of high-performance batteries suitable for a wide range of applications—from flexible electronics to medical devices.
"By applying folding and origami principles, we can create new shapes, structures, and features for paper-based energy storage," said Chen. "This field holds immense potential for future innovation."
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