In brief

Materials scientists developed flexible lithium-ion batteries using high energy density mechano-graded electrodes which show superior strength and durability over today’s gold standard batteries for wearable electronics.

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Flexing into the wearable technology future

20 Jun 2023

A new high-performance lithium-ion battery blends robust energy storage capabilities with flexibility to power the next generation of wearable technologies.

Line up circus performers and you’ll see a diverse range of body types that suit their acts—lean and flexible aerialists contrasted by the large, chiselled frames of strongmen. Similarly, lithium-ion batteries come in a spectrum of shapes and sizes uniquely designed to power wearable devices such as smartwatches and smart glasses.

Considering which type of battery works best for these devices is tricky business, said Shengkai Cao, a Research Scientist at A*STAR’s Institute of Materials Research & Engineering (IMRE). Batteries with high energy density electrodes can hold more power but they’re bulky and rigid, which can impact the usability of the wearable device.

“Such electrodes are thick, which can result in poor mechanical flexibility and susceptibility to mechanical fracture or peeling under bending, folding or other deformations,” explained Xiaodong Chen, a Principal Scientist and Science Director at IMRE and President’s Chair Professor in Material Science and Engineering at Nanyang Technological University (NTU), Singapore.

In collaboration with researchers from NTU and Fuzhou University, China, Chen and Cao took on the challenge of creating a novel class of foldable, high energy density lithium-ion batteries. The researchers’ first hurdle was to develop batteries that could balance the trade-off between energy capacity and mechanical flexibility.

To address this, the team turned to a relatively new technology in the field known as mechano-graded electrodes, which required extensive testing to optimise their functionality. “We had to link the mechanical properties with the electrodes’ electrochemical performance,” said Cao, adding that to do this, they deployed a combination of computational and experimental techniques.

Using Finite Element Analysis (a computerised method for predicting how materials respond to physical effects), Cao and colleagues found that their newly developed mechano-graded electrodes had exceptional power density and resilience.

“Most flexible materials gradually degrade at either the anode or cathode due to the highly reductive or oxidative environments over long-term use,” said Chen.

However, the team’s new-and-improved flexible lithium-ion batteries are a big step up—in stress tests, they retained their original electrochemical properties even after being twisted, knotted and folded.

Moreover, it’s easy to manufacture these batteries at commercial scales. “The protocol of fabricating mechano-graded electrodes is compatible with industrial equipment and can easily be scaled up using commercially available chemicals,” remarked Cao.

Moving forward, Chen and Cao aim to boost their innovation’s performance by up to 100-fold in a bid to redefine what’s possible with tomorrow’s wearable electronics.

The A*STAR researchers contributing to this research are from the Institute of Materials Research & Engineering (IMRE).

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Ge, X., Cao, S., Lv, Z., Zhu, Z., Tang, Y., et al. Mechano-graded electrodes Mitigate the Mismatch between Mechanical Reliability and Energy Density for Foldable Lithium-Ion Batteries. Advanced Materials. 34, 2206797 (2022). | article

About the Researchers

Shengkai Cao is currently a Research Scientist I at A*STAR’s Institute of Materials Research and Engineering (IMRE). He graduated from the School of Materials Science & Engineering (MSE) at Nanyang Technological University (NTU). His research focuses on carbon negative technologies, energy storage and conversion.
Xiaodong Chen is the Scientific Director at the Institute of Materials Research and Engineering, A*STAR. He is also the President’s Chair Professor in Materials Science and Engineering, Professor of Chemistry and Medicine at Nanyang Technological University, Singapore (NTU). Chen also serves as the Director of the Innovative Centre for Flexible Devices (iFLEX) at NTU, the Director of Max Planck – NTU Joint Lab for Artificial Senses and the Deputy Director of the Singapore Hybrid-Integrated Next-Generation μ-Electronics (SHINE) Centre. His research interests include mechano-materials science, senses digitalisation, flexible electronics technology and cyber-human interfaces. Chen is the Editor-in-Chief of ACS Nano and an editorial advisory board member for more than 15 international journals. He has also received prestigious accolades for his exceptional scientific contributions, including the Singapore President’s Science Award and the Friedrich Wilhelm Bessel Research Award.

This article was made for A*STAR Research by Wildtype Media Group