Newswise: Wearable devices have attracted attention for their potential as sensors that could monitor various biomarkers, a means of drug delivery, medical devices and more. For these portable devices to be functional and practical, they must have batteries that are stretchable and highly deformable. While there has been research on how to improve battery flexibility while maintaining battery life and other desirable properties, less attention has been paid to the importance of how to protect batteries from moisture and gases. As portable devices are exposed to the atmosphere, it is important to extend battery life while protecting against atmospheric moisture and gases. A team of researchers from Yokohama National University in Japan has developed an extensible packaging film for these batteries with high gas level and moisture barrier functionality, bringing the possibility of highly portable battery-powered devices closer. deformable as usual technology.
Their results were published in ACS Applied Materials & Interfaces on September 27.
“Currently, the use of solid and large batteries for stretchable devices is a problem in stretchable electronics ¾ meaning, while the sensors and interfaces are soft, the batteries still use hard batteries,” said l ‘corresponding author Hiroki Ota of the Yokohama Department of Mechanical Engineering. National University “Soft and extensible batteries have been studied in the world, but they cannot be used in air due to the high permeability to gas and moisture of the packaging materials of extensible batteries.”
To create this flexible film with a high gas barrier, the researchers coated a thin layer of liquid metal on 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 address the problem of gas and moisture permeability, but did not allow the necessary flexibility.
According to the researchers, the resulting film shows excellent oxygen impermeability under mechanical stress and extremely low moisture permeability. The stretchable lithium-ion battery they assembled in their studio 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 a stretchable battery, which could be used in the next generation of smart devices, including future wearable devices, films with high gas and moisture barrier properties can be achieved by using a new material called liquid metal,” Ota said.
This research holds the promise of being able to use batteries that have high energy density, high working voltage, and long-term stability and are also highly deformable, as opposed to bulky and inflexible, in wearable devices. As a result, the findings bring wearable devices closer to being more practical, opening up opportunities in medicine and health, as well as other fields.
“This research contributes to the social implementation of stretchable devices,” said Ota.
The next steps include improving the moisture protection ability of the film by modifying the materials. Another future direction is to improve the performance stability of batteries, even under deformation, by developing more suitable materials for their parts. Making the film profitable will also contribute to eventual scalability.
“Further cost reductions in developed film will lead to the implementation of stretchable batteries,” Ota said. “Also, the film could be useful as a barrier film for organic electronics and so on.”
Other authors of the work are: Yuki Nishitai, Satoru Mizuguchi, Yuji Isano, Sijie Ni, Koki Murakami and Masaki Shimamura, all from the Department of Mechanical Engineering at Yokohama National University; and Hiroki Iida and Kazuhide Ueno of 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 a hands-on education using the extensive experience of its faculty and facilitates engagement with the global community. YNU’s strength in academic research in applied sciences leads to high-impact publications and contributes to international scientific research and global society. For more information, see: