Tag Archives: Jing Ren

Self-healing lithium-ion batteries for textiles

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It’s easy to forget how hard we are on our textiles. We rip them, step on them, agitate them in water, splatter them with mud, and more. So, what happens when we integrate batteries and electronics into them? An Oct. 20, 2016 news item on phys.org describes one of the latest ‘textile batter technologies’,

Electronics that can be embedded in clothing are a growing trend. However, power sources remain a problem. In the journal Angewandte Chemie, scientists have now introduced thin, flexible, lithium ion batteries with self-healing properties that can be safely worn on the body. Even after completely breaking apart, the battery can grow back together without significant impact on its electrochemical properties.

wiley_selfhealinglithiumionbattery

© Wiley-VCH

An Oct. 20, 2016 Wiley Angewandte Chemie International Edition press release (also on EurekAlert), which originated the news item, describes some of the problems associated with lithium-ion batteries and this new technology designed to address them,

Existing lithium ion batteries for wearable electronics can be bent and rolled up without any problems, but can break when they are twisted too far or accidentally stepped on—which can happen often when being worn. This damage not only causes the battery to fail, it can also cause a safety problem: Flammable, toxic, or corrosive gases or liquids may leak out.

A team led by Yonggang Wang and Huisheng Peng has now developed a new family of lithium ion batteries that can overcome such accidents thanks to their amazing self-healing powers. In order for a complicated object like a battery to be made self-healing, all of its individual components must also be self-healing. The scientists from Fudan University (Shanghai, China), the Samsung Advanced Institute of Technology (South Korea), and the Samsung R&D Institute China, have now been able to accomplish this.

The electrodes in these batteries consist of layers of parallel carbon nanotubes. Between the layers, the scientists embedded the necessary lithium compounds in nanoparticle form (LiMn2O4 for one electrode, LiTi2(PO4)3 for the other). In contrast to conventional lithium ion batteries, the lithium compounds cannot leak out of the electrodes, either while in use or after a break. The thin layer electrodes are each fixed on a substrate of self-healing polymer. Between the electrodes is a novel, solvent-free electrolyte made from a cellulose-based gel with an aqueous lithium sulfate solution embedded in it. This gel electrolyte also serves as a separation layer between the electrodes.

After a break, it is only necessary to press the broken ends together for a few seconds for them to grow back together. Both the self-healing polymer and the carbon nanotubes “stick” back together perfectly. The parallel arrangement of the nanotubes allows them to come together much better than layers of disordered carbon nanotubes. The electrolyte also poses no problems. Whereas conventional electrolytes decompose immediately upon exposure to air, the new gel is stable. Free of organic solvents, it is neither flammable nor toxic, making it safe for this application.

The capacity and charging/discharging properties of a battery “armband” placed around a doll’s elbow were maintained, even after repeated break/self-healing cycles.

Here’s a link to and a citation for the paper,

A Self-Healing Aqueous Lithium-Ion Battery by Yang Zhao, Ye Zhang, Hao Sun, Xiaoli Dong, Jingyu Cao, Lie Wang, Yifan Xu, Jing Ren, Yunil Hwang, Dr. In Hyuk Son, Dr. Xianliang Huang, Prof. Yonggang Wang, and Prof. Huisheng Peng. Angewandte Chemie International Edition DOI: 10.1002/anie.201607951 Version of Record online: 12 OCT 2016

© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Stretchable carbon nanotubes as supercapacitors

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This Nov. 25, 2013 news item on phys.org was a bit of a walk down memory lane for me,

A mobile telephone display for your jacket sleeve, ECG probes for your workout clothes—wearable electronics are in demand. In order for textiles with built-in electronics to function over longer periods of time, all of the components need to be flexible and stretchable. In the journal Angewandte Chemie, Chinese researchers have now introduced a new type of supercapacitor that fulfills this requirement. Its components are fiber-shaped and based on carbon nanotubes.

The reference to a mobile telephone display on a jacket sleeve brought back memories of Nokia’s proposed Morph device,, from my Aug. 3, 2011 posting,

For anyone who’s not familiar with the Morph, it’s an idea that Nokia and the University of Cambridge’s Nanoscience Centre have been working on for the last few years. Originally announced as a type of flexible phone that you could wrap around your wrist, the Morph is now called a concept.  …

At the time I was writing about exploring the use of graphene to enable the morph (flexible phone). This latest work from China is focused on carbon nanotubes,. The Angewandte Chemie Nov. 25, 2013 press release, which originated the news item on phys.org,  provides more details,

For electronic devices to be incorporated into textiles or plastic films, their components must be stretchable. This is true for LEDS, solar cells, transistors, circuits, and batteries—as well as for the supercapacitors often used for static random access memory (SRAM). SRAM is often used as a cache in processors or for local storage on chips, as well as in devices that must maintain their data over several years with no source of power.

Previous stretchable electronic components have generally been produced in a conventional planar format, which has been an obstacle to their further development for use in small, lightweight, wearable electronics. Initial attempts to produce supercapacitors in the form of wires or fibers produced flexible—but not stretchable—components. However, stretchability is a required feature for a number of applications. For example, electronic textiles would easily tear if they were not stretchable.

A team led by Huisheng Peng at Fudan University has now developed a new family of highly stretchable, fiber-shaped, high-performance supercapacitors. The devices are made by a winding process with an elastic fiber at the core. The fiber is coated with an electrolyte gel and a thin layer of carbon nanotubes is wound around it like a sheet of paper. This is followed by a second layer of electrolyte gel, another layer of carbon nanotube wrap, and a final layer of electrolyte gel.

The delicate “sheets” of carbon nanotubes are produced by chemical vapor deposition and a spinning process. In the sheets this method produces, the tiny tubes are aligned in parallel. These types of layers display a remarkable combination of properties: They are highly flexible, tear-resistant, conductive, and thermally and mechanically stable. In the wound fibers, the two layers of carbon nanotubes act as electrodes. The electrolyte gel separates the electrodes from each other while stabilizing the nanotubes during stretching so that their alignment is maintained. This results in supercapacitor fibers with a high capacity that is maintained after many stretching cycles.

For the curious, here’s a link to and a citation for the paper,

A Highly Stretchable, Fiber-Shaped Supercapacitor by Zhibin Yang, Jue Deng, Xuli Chen, Jing Ren, and Prof. Huisheng Peng. Angewandte Chemie International Edition
Early View (Online Version of Record published before inclusion in an issue)Article first published online: 8 NOV 2013 DOI: 10.1002/anie.201307619

Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This article is behind a paywall.