Metallic glass-based materials in wearable energy storage devices

“The work breaks the stereotype that only traditional materials such as carbon-based network and organic fabric can be used in wearable devices, and shows for the first time that flexible metallic glass-based materials can also be used in wearable devices.”Zhifeng Wang

Researchers at Hebei University of Technology in Tianjin, China, with collaborators at RMIT University and Western Sydney University in Australia, have been examining possible applications for metallic glass materials and its dealloyed products, usually nanoporous materials. In a new study, they demonstrated an approach to synthesizing flexible nickel oxide/hydroxide coated nanoporous nickel electrodes containing a metallic glass sandwich-like interlayer that could lead to wearable all-solid-state supercapacitors with excellent performance.

It has been a challenge to design and prepare nanoporous metal/metallic oxides electrodes with good flexibility, as well as high-energy storage performance, for applications in wearable electronic products. However, this study, which was reported in the journal Applied Materials Today [Qin et al. Appl. Mater. Today (2020) DOI: 10.1016/j.apmt.2019.100539], proposes a straightforward approach for assembling such electrodes into a wearable cable-like supercapacitor, with the fabricated composite demonstrating good performance.

When a nickel-based metallic glass layer with useful flexibility and elasticity was introduced into nanoporous metals, the overall material with a sandwich-like structure still maintained exceptional flexibility. In such circumstances, the usual issue of the brittleness of nanoporous metals, which tends to limit their application, can therefore be resolved by the introduction of the metallic glass. The breakthrough showed that such flexible metallic glass-based sandwich-like materials can be effective in wearable all-solid supercapacitors and can last for a long time under repeated bending, indicating that it meets the basic lifetime requirement for applications.

With most research in the field of metallic glass being focused on its mechanical properties, corrosion resistance and magnetic properties, it was not expected that a metallic material could be directly applied in wearable energy storage. However, the cable-like all-solid-state supercapacitor was shown to be capable of producing sufficient power to run a digital watch for over 25?minutes. As team leader Zhifeng Wang told Materials Today, “The work breaks the stereotype that only traditional materials such as carbon-based network and organic fabric can be used in wearable devices, and shows for the first time that flexible metallic glass-based materials can also be used in wearable devices”.

The researchers hope that flexible wearable metallic glass-based materials with substantially improved mechanical and electrochemical properties can be developed with the assistance of high-accuracy calculations, as well as materials genome and machine learning. In the future, the flexible metallic glass ribbon could also be processed by micro-electromechanical systems (MEMS) and, by connecting to a nanogenerator, be able to power wearable human health care devices.