Graphene supercapacitor breaks storage record
December 10, 2010 // Julien Happich
Researchers in the US have made a graphene-based supercapacitor that can store as much energy per unit mass as nickel metal hydride batteries - but unlike batteries, it can be charged or discharged in just minutes or even seconds. The new device has a specific energy density of 85.6 Wh/kg at room temperature and 136 Wh/kg at 80 °C. These are the highest ever values for "electric double layer" supercapacitors based on carbon nanomaterials.
The new device was made by Bor Jang of US-based Nanotek Instruments and colleagues. It has electrodes made of graphene mixed with 5wt% Super P (an acetylene black that acts as a conductive additive) and 10wt% PTFE binder. A sheet of carbon just one atom thick, graphene is a very good electrical conductor as well as being extremely strong and flexible.The researchers coat the resulting slurry onto the surface of a current collector and assemble coin-sized capacitors in a glove box. The energy density values of the supercapacitor are comparable to that of nickel metal hydride batteries. "This new technology makes for an energy storage device that stores nearly as much energy as in a battery but which can be recharged in seconds or minutes," Jang explained. "We believe that this is truly a breakthrough in energy technology." The device might be used to recharge mobile phones, digital cameras and micro-EVs, he adds.
The team, which includes scientists from Angstron Materials in the US and Dalian University of Technology in China, are now working hard to further improve the energy density of the device. "Our goal is to make a supercapacitor that stores as much energy as the best lithium-ion batteries (for the same weight) but which can still be recharged in less than two minutes," said Jang.
His team first discovered that graphene could be used as a supercapacitor electrode material in 2006. Since then, scientists around the world have made great strides in improving the specific capacitance of these electrodes but the devices still fall short of the theoretical capacitance values of 550 F/g.
"Despite the theoretically high specific surface area of single-layer graphene (which can reach up to 2.675 m2/g), a supercapacitance of 550 F/g has not been reached in a real device because the graphene sheets tend to re-stack together," explained Jang. "We are trying to overcome this problem by developing a strategy that prevents the graphene sheets from sticking to each other face-to-face. This can be achieved if curved graphene sheets are used instead of flat ones."
Curved graphene sheets: Source Physicsworld
Graphene bandgap opened by vapor
Do we need more wireless standards in an M2M world?
April 24, 2014
Matthias Poppel, chief operating officer for EnOcean GmbH, reckons established wireless protocols can gain traction in machine-to-machine ...
Analog helps drive TI's Q1 profit
Strained nanowire has tunable electroptic properties
Can wind turbines generate lightning?
Transaction-level modeling and verification extensions for SystemC
Epistar extends LED collaboration with Intermolecular
April 24, 2014
Intermolecular, Inc. has signed a multi-year extension with Epistar Corp. of their existing collaborative development program ...
Anritsu gives away a handheld spectrum analyzer
Silicon anode technology gears up for production volumes
Cadence breaks into top four in semi IP core ranking
- USB 5V 2.5A Output, 42V Input Synchronous Buck with Cable Drop Compensation
- Measurement applications across multiple test platforms
- Supplying DC input power to string inverters
- Supplying DC input power for HEV testing
InterviewHeartbleed challenges the Internet of Thing
The Heartbleed security bug is a key example of the fundamental security challenge for the Internet of Things says Green Hills Software as it launches a new security group.
Filter WizardCheck out the Filter Wizard Series of articles by Filter Guru Kendall Castor-Perry which provide invaluable practical Analog Design guidelines.
Linear video channel
READER OFFERRead more
This month, Arrow Electronics is giving away ten XMC1200 lighting application kits, worth 100 Euros each, for EETimes Europe's readers to win.
Each kit combines Infineon’s brightness and colour control XMC1200 CPU board to drive flicker free LED dimming and colour changing, together with a colour LED card and a white LED card.
December 15, 2011 | Texas instruments | 222901974
Unique Ser/Des technology supports encrypted video and audio content with full duplex bi-directional control channel over a single wire interface.