Wirelessly Charged Flexible Li-Ion Batteries

A flexible, thin battery that can be wirelessly charged could be used to power the next generation of wearable devices.

AsianScientist (Mar. 31, 2015) – Researchers have invented a flexible lithium ion battery that is thinner than a credit card and can be charged wirelessly. Their results have been published in Nano Letters.

Lithium ion batteries are widely used today in various electronics including mobile devices and electronic cars. The researchers said that their work could help accelerate the development of flexible and wearable electronics.

Conventional lithium ion batteries are manufactured based on a layering technology, stacking up anodes, separating films and cathodes like a sandwich, which makes it difficult to reduce their thickness. In addition, friction arises between layers, making the batteries impossible to bend. The coating films of electrodes easily come off, which contributes to the batteries’ poor performance.

Instead, a team of researchers led by Professor Choi Jang Wook Choi from the Korea Advanced Institute of Science and Technology (KAIST) and Dr. Song Jae Yong at the Korea Research Institute of Standards and Science removed the separating films, layered the cathodes and anodes collinearly on a plane, and created a partition between electrodes. This eliminated potential problems such as short circuits and voltage dips commonly present in lithium ion batteries.

After more than five thousand consecutive flexing experiments, the research team confirmed the possibility of a more flexible electrode structure while maintaining the battery performance comparable to the level of current lithium ion batteries.

Flexible batteries can be applied to integrated smart cards, cosmetic and medical patches, and skin adhesive sensors that can control a computer with voice commands or gestures. Moreover, the team has successfully developed wireless-charging technology using electromagnetic induction and solar batteries.

They are currently developing a mass production process to combine this planar battery technology and printing, to ultimately create a new paradigm to print semiconductors and batteries using 3D printers.

Professor Choi said, “This new technology will contribute to diversifying patch functions as it is applicable to power various adhesive medical patches.”

The article can be found at: Kim et al. (2015) A Half Millimeter Thick Coplanar Flexible Battery with Wireless Recharging Capability.

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Source: KAIST.
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