Drawing inspiration from plants: A metal-air paper battery for wearable devices

For over two millennia, paper has been a staple of human civilization. But these days, the usage of paper is not limited to writing. It is also playing a pivotal role in ushering in a greener future.

Lightweight and thin paper-based devices help reduce dependence on metal or plastic materials, whilst at the same time being easier to dispose of. From paper-based diagnostic devices that deliver economical and rapid detection of infectious diseases to batteries and energy devices that offer an environmentally friendly alternative for power generation, scientists are finding ingenious ways to put this versatile material to use.

Now, a team of researchers at Tohoku University has reported on a high-performance magnesium-air (Mg-air) battery that is paper-based and activated by water.

"We drew inspiration for this device from the respiration mechanism of plants," points out Hiroshi Yabu, corresponding authors of the study. "Photosynthesis is analogous to the charge and discharge process in batteries. Just as plants harness solar energy to synthesize sugar from water in the ground and carbon dioxide from the air, our battery utilizes magnesium as a substrate to generate power from oxygen and water."

To fabricate the battery, Yabu and his colleagues bonded magnesium foil onto paper and added the cathode catalyst and gas diffusion layer directly to the other side of the paper. The paper battery achieved an open circuit voltage of 1.8 volts, a 1.0 volt current density of 100 mA/cm², and a maximum output of 103 milliwatts/cm².

"Not only did the battery demonstrate impressive performance results, it operates without using toxic materials - instead using carbon cathodes and a pigment electrocatalyst that have passed stringent assessments," adds Yabu.

The researchers put the battery to the test in a pulse oximeter sensor and a gps sensor, illustrating its versatility for wearable devices.

Details of their research were published in the journal RSC Applied Interfaces on March 18, 2024.

About the World Premier International Research Center Initiative (WPI)

The WPI program was launched in 2007 by Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT) to foster globally visible research centers boasting the highest standards and outstanding research environments. Numbering more than a dozen and operating at institutions throughout the country, these centers are given a high degree of autonomy, allowing them to engage in innovative modes of management and research. The program is administered by the Japan Society for the Promotion of Science (JSPS).

See the latest research news from the centers at the WPI News Portal: https://www.eurekalert.org/newsportal/WPI

Main WPI program site: www.jsps.go.jp/english/e-toplevel

Advanced Institute for Materials Research (AIMR), Tohoku University

Establishing a World-Leading Research Center for Materials Science:

AIMR aims to contribute to society through its actions as a world-leading research center for materials science and push the boundaries of research frontiers. To this end, the institute gathers excellent researchers in the fields of physics, chemistry, materials science, engineering, and mathematics and provides a world-class research environment.

AIMR site: https://www.wpi-aimr.tohoku.ac.jp/en/