Navigation Links
Is there a micro-supercapacitor in your future?
Date:4/26/2010

"Just think how often your fancy new mobile phone or computer has become little more than a paperweight because the battery lost its zeal for doing its job," says John Chmiola, a chemist with the Lawrence Berkeley National Laboratory (Berkeley Lab). "At a time when cellphones can do more than computers could do at the beginning of the Clinton presidancy, it would be an understatement to say that batteries have not been holding up their end of the mobile device bargain."

Chmiola is a staff scientist in the Advanced Energy Technologies Department of Berkeley Lab's Environmental Energy Technologies Division. His research is aimed at addressing this problem of relatively short-lived portable energy storage devices. Chmiola believes he has found a solution in electrochemical capacitors, which are commonly referred to as "supercapacitors" because of their higher energy storage densities than conventional dielectric capacitors and higher abuse tolerance than batteries.

In a paper published in the April 23, 2010 issue of the journal Science, titled "Monolithic Carbide-Derived Carbon Films for Micro-Supercapacitors," Chmiola and Yury Gogotsi of Drexel University, along with other co-authors, describe a unique new technique for integrating high performance micro-sized supercapacitors into a variety of portable electronic devices through common microfabrication techniques.

By etching electrodes made of monolithic carbon film into a conducting substrate of titanium carbide, Chmiola and Gogotsi were able to create micro-supercapacitors featuring an energy storage density that was at least double that of the best supercapacitors now available. When used in combination with microbatteries, the power densities and rapid-fire cycle times of these micro-supercapacitors should substantially boost the performance and longevity of portable electric energy storage devices.

"The prospect of integrating batteries and supercapacitors with the micro-electromechanical systems (MEMS) they power represents a conceptual leap forward over existing methods for powering such devices," Chmiola says. "Furthermore, since the same fabrication processes that produced the devices needing the electrical energy also produced the devices storing that energy, we provide a framework for potentially increasing the density of microelectronic devices and allowing improved functionality, reduced complexity, and enhanced redundancy."

The two principal systems today for storing electrical energy are batteries and supercapacitors. Batteries store electrical energy in the form of chemical reactants and generally display even higher energy storage densities than supercapacitors. However, the charging and discharging of a battery exact a physical toll on electrodes that eventually ends the battery's life after several thousand charge-discharge cycles. In supercapacitors, energy is stored as electrical charge, which does not impact electrodes during operation. This allows supercapacitors to be charged and discharged millions of times.

"We have known for some time that supercapacitors are faster and longer-lasting alternatives to conventional batteries," Gogotsi says, "so we decided to see if it would be possible to incorporate them into microelectronic devices and if there would be any advantage to doing so."

Chmiola and Gogotsi chose titanium carbide as the substrate in this study because while all metal carbides can be selectively etched with halogens so that a monolithic carbon film is left behind, titanium carbide is readily available, relatively inexpensive and can be used at the same temperatures as other microfabrication processes.

"Plus, we have a body of work on titanium carbide precursor carbons that provided us with a lot of data to draw from for understanding the underlying science," Chmiola says.

The process started with titanium carbide ceramic plates being cut to size and polished to a thinness of approximately 300 micrometers. The titanium was then selectively etched from one face of the plate using chlorine at elevated temperatures, a process that is similar to current dry-etching techniques for MEMS and microchip fabrications.

Chlorinating the titanium removed the metal atoms and left in place a monolithic carbon film, a material with a proven track record in supercapacitors produced via the traditional "sandwich construction" technique.

"By using microfabrication techniques to produce our supercapacitors we avoided many of the pitfalls of the traditional method," says Chmiola, "namely poor contact between electro-active particles in the electrode, large void spaces between particles that don't store charge, and poor contact between the electro-active materials and the external circuitry."

The electrical charge storage densities of the micro-supercapacitors were measured in two common electrolytes. As promising as the results were, Chmiola notes the impressive figures were achieved without the "decades of optimization" that other electronic devices have undergone. This, he says, "hints at the possibility that the energy density ceiling for microfabricated supercapacitors is, indeed, quite high."

Adds Gogotsi, "Given their practically infinite cycle life, micro-supercapacitors seem ideal for capturing and storing energy from renewable resources and for on-chip operations."

The next step of the work is to scale down the size of the electrodes and improve the dry etching procedure for removing metal atoms from metal carbides to make the process even more compatible with commercial microfabrication technology. At Berkeley Lab, Chmiola is working on the development of new electrolytes that can help increase the energy storage densities of his micro-supercapacitors. He is also investigating the factors that control the usable voltage window of different electrolytes at a carbon electrode.

"My ultimate goals are to increase energy stored to levels closer to batteries, and preserve both the million-plus charge-discharge cycles and recharge times of less than five minutes of these devices," says Chmiola. "I think this is what the end users of portable energy storage devices really desire."


'/>"/>

Contact: Lynn Yarris
lcyarris@lbl.gov
510-486-5375
DOE/Lawrence Berkeley National Laboratory
Source:Eurekalert  

Related biology technology :

1. Senate President Therese Murray, Massachusetts Life Sciences Center, and Howard Hughes Medical Institute Join Marine Biological Laboratory (MBL) for Loeb Laboratory Groundbreaking Ceremony
2. Let there be light: Teaching magnets to do more than just stick around
3. NPL research shows there could be no end in sight for Moore’s Law
4. Tethered molecules act as light-driven reversible nanoswitches
5. Diverse Coalition of Purchasers Respond to BIO CEO Fly-In: There is Another Side to The Story
6. Tethered to chip, energy supply that drives sperm could power nanobot
7. Let there be light: new magnet design continues magnet labs tradition of innovation
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Is there a micro-supercapacitor in your future?
(Date:4/29/2016)... , April 29, 2016 ... by Transparency Market Research "Separation Systems for Commercial ... Growth, Trends, and Forecast 2015 - 2023", the ... at US$ 10,665.5 Mn in 2014 and is ... from 2015 to 2023 to reach US$ 19,227.8 ...
(Date:4/29/2016)... Louisville, KY and San Diego, CA (PRWEB) , ... April 29, ... ... the National Stem Cell Foundation (NSCF) to support the development of a patient-specific stem ... by Dr. Andrés Bratt-Leal in the lab of Dr. Jeanne Loring at The Scripps ...
(Date:4/29/2016)... TURIN, Italy , April 29, 2016 ... version 5.11, the latest update to its industry-leading treatment ... has shown that Monaco version ... Users can now attain calculation speeds up to four ... Monaco . With the industry,s gold standard ...
(Date:4/28/2016)... 2016 Q BioMed Inc. ... CEO  was featured in an article he wrote ... Fear To Tread: http://www.lifescienceleader.com/doc/accelerators-enter-when-vcs-fear-to-tread-0001 ... is an essential business journal for life science ... to Big Pharmas. Their content is designed to ...
Breaking Biology Technology:
(Date:3/17/2016)... ABI Research, the leader in transformative ... market will reach more than $30 billion by ... Consumer electronics, particularly smartphones, continue to boost the ... reach two billion shipments by 2021 at a ... Research Analyst at ABI Research. "Surveillance is also ...
(Date:3/14/2016)... March 14, 2016 NXTD ) ("NXT-ID" ... commerce market, announces the airing of a new series of ... week of March 21 st .  The commercials will air ... popular Squawk on the Street show. --> NXTD ... growing mobile commerce market, announces the airing of a new ...
(Date:3/11/2016)... India , March 11, 2016 ... a new market research report "Image Recognition Market by ... Application (Marketing and Advertising), by Deployment Type (On-Premises and ... Forecast To 2022", published by MarketsandMarkets, the global market ... 2015 to USD 29.98 Billion by 2020, at a ...
Breaking Biology News(10 mins):