Elastic wire-shaped lithium ion batteries with high electrochemical performance
Flexible smartphones, “intelligent” bracelets, glasses with a built-in computer: for these trends to take off, we need suitable power systems. Chinese scientists have now developed a wire-shaped lithium ion battery that contains electrodes consisting of two composite yarns made of carbon nanotubes and lithium titanium oxide or lithium manganese oxide. As the researchers report in the journal Angewandte Chemie, they were able to weave their batteries into light, flexible, elastic, and safe textile batteries with a high energy density.
Previous methods for producing wire-shaped electrochemical supercapacitors by twisting two fiber electrodes together resulted in systems with inferior performance that prevented them from being brought to the market. Lithium ion batteries can attain significantly higher energy density, but have not previously been produced in wire form.
In addition to other barriers, the safety problems associated with lithium ion batteries really come into play. The source of the safety problem is dendritic lithium, which can form during over-charging, “growing” out of the anode and causing a short circuit. This can cause the battery to ignite. This seems especially critical for wire-shaped batteries that can be stretched, twisted, and bent during use.
A team led by Huisheng Peng from Fudan University in Shanghai has now succeeded in producing wire-shaped lithium ion batteries that have a high energy density and are also safe. Their success results from the special structure as well as the materials used. The anode and cathode are two fibers made of parallel multiwalled carbon nanotubes that contain either lithium titanium oxide (LTO) or lithium manganese oxide (LMO) particles, respectively.
When the battery is charging, lithium ions are transferred from the LMO lattice to the electrolyte and then into the LTO lattice of the anode. The reverse process occurs as the battery is being discharged. Because the Li insertion takes place at ~1.5 V (vs. Li/Li+) for the applied LTO composite electrode, the chance of short circuit caused by dendritic lithium would be small and therefore the batteries are safe.
The parallel arrangements of continuous carbon nanotubes hold the nanoparticles; they are also efficient pathways for charge transport and serve as current collectors. The two electrode yarns are arranged in parallel, separated by a layer of insulator, and enclosed in a heat-shrinkable tube.
To make the wires elastic, they can be wrapped around an elastic fiber such as polydimethylsiloxane and coated with a thin-layer gel electrolyte. Neither repeated stretching to twice its original length nor thousands of deformation cycles reduces the battery capacity.
The wire-shaped batteries can be spun into long fibers and woven into a fabric that can be incorporated into textiles.
About the Author
Dr. Huisheng Peng is a Professor of Department of Macromolecular Science and Laboratory of Advanced Materials at Fudan University. His research centers on functional composite materials and their energy applications. Peng and co-workers created aligned carbon nanotube/polymer composites and developed novel wire-shaped solar cells, Li-ion batteries, and supercapacitors.
Author: Huisheng Peng, Fudan University, Shanghai (China), http://www.polymer.fudan.edu.cn/polymer/research/Penghs/member_en.htm
Title: Elastic and Wearable Wire-Shaped Lithium-Ion Battery with High Electrochemical Performance
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201402388
Huisheng Peng | Angewandte Chemie
Two decades of training students and experts in tracking infectious disease
27.11.2015 | Hochschule für Angewandte Wissenschaften Hamburg
Increased carbon dioxide enhances plankton growth, opposite of what was expected
27.11.2015 | Bigelow Laboratory for Ocean Sciences
Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.
Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...
The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...
Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.
In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...
In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.
Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...
Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...
25.11.2015 | Event News
17.11.2015 | Event News
21.10.2015 | Event News
27.11.2015 | Press release
27.11.2015 | Life Sciences
27.11.2015 | Materials Sciences