When it comes to 3D printing, the sky is the limit. As 3D printing technology continues to advance, applications can be as far reaching as airplane and automobile parts to medical devices and even anatomically correct, biocompatible models. Although 3D printing technology is developing at a rapid pace, the technology itself is not new. It emerged in the 1980s as a means of creating rapid prototypes. In recent years the applications for 3D printed models have evolved with the available hardware, software, and printable materials. Evolving technology, paired with the creative and innovative minds of scientists, engineers, and physicians, has been the launching pad for developments within 3D printing technology specific to healthcare. One way 3D printing technology is poised to create better patient outcomes is in creating an anatomically and patient-specific models to aid in surgery and medical procedures. With the capability to 3D ...
Nowadays we can’t imagine our lives without portable electronics, with many of our daily activities depending on cell phones, tablets, and laptops. Rechargeable batteries make it all possible. The market for rechargeable batteries is constantly expanding as electronics adapt to our needs, from implantable devices to electric cars. The lithium-ion battery market is estimated to exceed $60 billion by 2020.
Introduced in 1991, lithium-ion batteries have become very common and are widely used in consumer electronics, electric vehicles, and military and aerospace applications due to their high energy densities and ability to keep a charge. Lithium-ion batteries use complexes of lithium salts in a mix of organic solvents (ethylene, dimethyl and diethyl carbonates) as an electrolyte that carries the charge between the electrodes.
Safety Risk
The flammability of these solvents poses safety risks. If a Li-ion battery is overheated or overcharged, it can suffer thermal runaway, leading to cell rupture and, in extreme cases, to combustion. Seeking alternatives to the flammable solvents used in lithium-ion batteries has been a subject of intensive research for a number of years, with low volatility ionic liquids (or liquid salts) being one of the options investigated. An important recent breakthrough is the use of polymers.
Scientists from the University of North Carolina at Chapel Hill, North Carolina State University and Lawrence Berkeley National Laboratory discovered that polymers can be efficiently used as nonflammable electrolytes in lithium ion batteries. The work has been published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). Here is what the authors say about the significance of their research:
This research article describes a unique class of nonflammable electrolytes for lithium-ion batteries that are based on functionalized perfluoropolyethers (PFPEs). It demonstrates that PFPEs may be used as a major component in operating batteries. These electrolytes not only are completely nonflammable, but they also exhibit unprecedented high transference numbers and low electrochemical polarization, indicative of longer battery life. The results in this work may represent a significant step toward a lithium-ion battery with improved safety and pave the way for the development of new electrolytes that can address the persisting challenges of current battery technologies.
To make the nonflammable electrolytes, the scientists used chemically resistant, low molecular weight perfluoropolyether polymers, which remain in liquid state over a wide temperature range. The polymers were end-modified with ionic methyl carbonate groups. Such polymers mixed well with a lithium salt commonly used in batteries applications. The interaction with a polymer was proven by IR Spectroscopy.
Mixed Results
While ionic conductivity of the lithium salt-polymer electrolyte remained significantly lower when compared to commonly used flammable electrolytes, the new polymer electrolytes were characterized by very high transference numbers, characterizing high efficiency of the ion transfer to and from the electrode, which is beneficial for the battery performance. The testing of initial battery prototypes was successful, marking the first step towards “intrinsically safe” lithium-ion battery electrolytes:
By developing PFPEDMC, we have incorporated compatibility with lithium salts in an inherently nonflammable material. The resulting electrolytes exhibit reasonable conductivity and unprecedented transference numbers. Their compatibility with standard battery electrodes provides the opportunity for seamless integration into current manufacturing infrastructure.
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