Expandable battery packaging with a moisture and gas barrier could power the future of portable devices

Newswise – Wearable devices have drawn attention for their potential as sensors capable of monitoring various biomarkers, a means of drug delivery, medical devices and more. For these portable devices to be functional and practical, they must have expandable and highly deformable batteries. Although there has been research into how to improve battery flexibility while maintaining battery life and other desirable properties, less attention has been paid to the importance of battery protection against humidity and gases. Since portable devices are exposed to the atmosphere, it is important to extend battery life while protecting the batteries from moisture and atmospheric gases. moisture barrier functionality, bringing closer the possibility of portable devices with highly deformable batteries as a common technology.

Their results were published in Applied materials and ACS interfaces September 27.

“Currently, the use of strong and large batteries for stretchable devices is a problem in stretchable electronics ¾ i.e., although the sensors and interfaces are soft, the batteries still use hard batteries said corresponding author Hiroki Ota of Yokohama’s Department of Mechanical Engineering. National University. “Soft and expandable batteries have been studied globally but cannot be used in air due to the high gas and moisture permeability of expandable battery packaging materials.”

To create this flexible film with a high gas barrier, the researchers deposited a thin layer of liquid metal onto a gold-deposited thermoplastic polyurethane film using the layer-by-layer method. This method allowed the desired deformability, unlike aluminum laminated films, which were previously used to solve the problem of gas and moisture permeability, but did not allow the necessary flexibility.

According to the researchers, the resulting film exhibits excellent impermeability to oxygen gas under mechanical stress and extremely low moisture permeability. The stretchable lithium-ion battery they assembled in their study was able to operate reliably in air thanks to the stretchable gas barrier film they developed.

“It is exciting that in addition to the development of an expandable battery, which could be used in the next generation of smart devices, including future wearables, films with high barrier properties against gases and moisture can be achieved using a new material called liquid metal,” Ota said.

This research promises to be able to use batteries that have high energy density, high operating voltage and long-term stability and that are also highly deformable – as opposed to bulky and inflexible – in portable devices. As a result, discoveries are bringing wearable devices closer to becoming more practical, opening up opportunities in medicine and health as well as other fields.

“This research contributes to the social implementation of stretchable devices,” Ota said.

Next steps include improving the moisture barrier ability of the film by modifying the materials. Another future direction is to improve the performance stability of batteries, even under deformation, by developing materials better suited to its components. Making the movie profitable will also help with eventual scalability.

“Further reductions in developed film costs will lead to the implementation of expandable batteries,” Ota said. “Additionally, the film could be useful as a barrier film for organic electronics, etc.”

The other authors of the article are: Yuki Nishitai, Satoru Mizuguchi, Yuji Isano, Sijie Ni, Koki Murakami and Masaki Shimamura, all from the Department of Mechanical Engineering, Yokohama National University; and Hiroki Iida and Kazuhide Ueno from the Department of Chemistry and Life Sciences, Yokohama National University.

JSPS KAKENHI, Pfizer Health Research Foundation and JST CREST partially supported this work.

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Yokohama National University (YNU or Yokokoku) is a Japanese national university founded in 1949. YNU provides students with hands-on education using the vast expertise of its faculty and facilitates engagement with the global community. YNU’s strength in academic research of practical application sciences leads to high-impact publications and contributes to international scientific research and global society. For more information, please see: https://www.ynu.ac.jp/english/