Navigation Links
Clay key to high-temperature supercapacitors
Date:9/3/2013

HOUSTON (Sept. 3, 2013) Clay, an abundant and cheap natural material, is a key ingredient in a supercapacitor that can operate at very high temperatures, according to Rice University researchers who have developed such a device.

The Rice group of materials scientist Pulickel Ajayan reported today in Nature's online journal, Scientific Reports that the supercapacitor is reliable at temperatures of up to 200 degrees Celsius (392 degrees Fahrenheit) and possibly beyond. It could be useful for powering devices for use in extreme environments, such as oil drilling, the military and space.

"Our intention is to completely move away from conventional liquid or gel-type electrolytes, which have been limited to low-temperature operation of electrochemical devices," said Arava Leela Mohana Reddy, lead author and a former research scientist at Rice.

"We found that a clay-based membrane electrolyte is a game-changing breakthrough that overcomes one of the key limitations of high-temperature operation of electrochemical energy devices," Reddy said. "By allowing safe operation over a wide range of temperatures without compromising on high energy, power and cycle life, we believe we can dramatically enhance or even eliminate the need for expensive thermal management systems."

A supercapacitor combines the best qualities of capacitors that charge in seconds and discharge energy in a burst and rechargeable batteries that charge slowly but release energy on demand over time. The ideal supercapacitor would charge quickly, store energy and release it as needed.

"Researchers have been trying for years to make energy storage devices like batteries and supercapacitors that work reliably in high-temperature environments, but this has been challenging, given the traditional materials used to build these devices," Ajayan said.

In particular, researchers have struggled to find an electrolyte, which conducts ions between a battery's electrodes, that won't break down when the heat is on. Another issue has been finding a separator that won't shrink at high temperatures and lead to short circuits. (The separator keeps the electrolyte on the anode and cathode sides of a traditional battery apart while allowing ions to pass through).

"Our innovation has been to identify an unconventional electrolyte/separator system that remains stable at high temperatures," Ajayan said.

The Rice researchers led by Reddy and Rachel Borges solved both problems at once. First, they investigated using room-temperature ionic liquids (RTILs) developed in 2009 by European and Australian researchers. RTILs show low conductivity at room temperature but become less viscous and more conductive when heated.

Clay has high thermal stability, high sorption capacity, a large active surface area and high permeability, Reddy said, and is commonly used in muds for oil drilling, in modern construction, in medical applications and as a binder by iron and steel foundries.

After combining equal amounts of RTIL and naturally occurring Bentonite clay into a composite paste, the researchers sandwiched it between layers of reduced graphene oxide and two current collectors to form a supercapacitor. Tests and subsequent electron microscope images of the device showed no change in the materials after heating it to 200 degrees Celsius. In fact, Reddy said, there was very little change in the material up to 300 degrees Celsius.

"The ionic conductivity increases almost linearly until the material reaches 180 degrees, and then saturates at 200," he said.

Despite a slight drop in capacity observed in the initial charge/discharge cycles, the supercapacitors were stable through 10,000 test cycles. Both energy and power density improved by two orders of magnitude as the operating temperature increased from room temperature to 200 degrees Celsius, the researchers found.

The team took its discovery a step further and combined the RTIL/clay with a small amount of thermoplastic polyurethane to form a membrane sheet that can be cut into various shapes and sizes, which allows design flexibility for devices.


'/>"/>

Contact: Mike Williams
mikewilliams@rice.edu
713-348-6728
Rice University
Source:Eurekalert

Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/27/2017)... , March 27, 2017  Catholic Health ... and Management Systems Society (HIMSS) Analytics for achieving ... Adoption Model sm . In addition, CHS previously ... U.S. hospitals using an electronic medical record (EMR). ... its high level of EMR usage in an ...
(Date:3/24/2017)... , Mar 24, 2017 Research and Markets ... System Market Analysis & Trends - Industry Forecast to 2025" ... ... grow at a CAGR of around 15.1% over the next decade ... industry report analyzes the market estimates and forecasts for all the ...
(Date:3/23/2017)... Research and Markets has announced the addition ... - Industry Forecast to 2025" report to their offering. ... The Global Vehicle ... around 8.8% over the next decade to reach approximately $14.21 billion ... estimates and forecasts for all the given segments on global as ...
Breaking Biology News(10 mins):
(Date:9/19/2017)... ... 19, 2017 , ... Molecular Devices, LLC, a leader in ... launch the CloneSelect™ Single-Cell Printer™ in North America. This novel system utilizes ... visual documentation of monoclonality for use in cell line development. , Clonal ...
(Date:9/18/2017)... ... September 18, 2017 , ... Transportable biomass conversion facilities ... torrefied wood is the topic of a September 27 webinar hosted ... viability of transportable biomass conversion facilities for producing biochar, briquettes, and torrefied wood, ...
(Date:9/18/2017)... ... September 18, 2017 , ... ... optimization firm for the life sciences and healthcare industries, announces Bryan Coddington ... , What: Digital Transformation in Medical Device – The Journey to FDA Compliant ...
(Date:9/14/2017)... ... September 14, 2017 , ... ... formally introduces its flexible scientist program (FSP)-- a flexible business approach similar ... FSP, which combines SSCI’s extensive project-based analytical and solid-state chemistry services and ...
Breaking Biology Technology: