Researchers Develop a New Hybrid Supercapacitor Technology with High Energy Density and Power
Queensland University of Technology researchers are working to develop a new hybrid supercapacitor with high energy density and power by combining elements of a capacitor and battery in one device.
Researchers from the Queensland University of Technology (QUT) have developed a new type of energy storage technology that combines the best of both worlds. At present, batteries, and supercapacitors each have pros and cons in terms of performance. Batteries typically offer a greater energy density and have a higher breakdown voltage. In comparison, supercapacitors exhibit a longer life expectancy, reduced weight, and have a far greater power density (or much faster charge and discharge rates).
The recently developed hybrid supercapacitor from QUT combines particular structural elements of a battery with a supercapacitor.
Image used courtesy of QUT
A High-Power Hybrid Supercapacitor
Research published in the journal Advanced Materials, Associate Professor Deepak Dubal and fellow researchers, including Professor Nunzio Motta and Ph.D. researcher Michael Horn, explain their findings in more detail. The QUT team combined the capacitor-type titanium carbide-based negative electrode with a battery-type graphene-hybrid positive electrode to create their new hybrid energy storage device.
The researchers observed that the hybrid device was able to achieve an energy density that emulated that of nickel-metal hydride (NiMH) batteries. These batteries typically exhibit a relatively high energy density of around 170–420 Wh/L. Additionally, the hybrid device developed at QUT provided an ultra-high power comparable to that displayed by supercapacitors. This power was also described as being 10 times greater than that recorded lithium-ion batteries (LIBs).
Energy Storage Capacity
It is common for batteries on today’s market to fail if they are cycled over and over again at high rates. In a news release from QUT, Horn said, “even if you use modest cycling rates and low depth of discharge to get a really long life, batteries could maybe reach 5000 charge/discharge cycles.” Horn added: “However, our device, after being cycled at a high current rate for 10,000 charge/discharges, retained around 90 percent of its initial storage capacity.”
Research Challenges and Structural Design
The main challenge faced by the researchers was developing the hybrid device so that the beneficial performance qualities of both suitable capacitor-type negative electrodes and battery-type positive electrodes could be combined. The QUT researchers worked with international collaborators from the Indian Institute of Technology (IIT) Jammu, India (Dr Jayaram Kolleboyina) and the Technical University (TU) Munich, Germany (Professor Roland Fischer) to solve this challenge.
Together, the researchers developed graphene-based hybrid materials for positive electrodes. Graphene is another form of carbon, whereby carbon atoms are arranged in a single layer of a 2-dimensional (2D) honeycomb lattice. The team produced a chemically-altered graphene material and combined it with a nano-structured metal organic framework (MOF).
Associate Professor Deepak Dubal from QUT’s Centre for Materials Science. Image used courtesy of QUT
“The beauty of this hybrid material is the synergic combination,” said Professor Dubal.
The metal organic framework, Dubal said, stores charge through a chemical mechanism, while the graphene provides electrical connections back to the MOF.
“It’s a win-win solution. This is a step towards energy storage solutions that are cheaper, extremely safe, and environmentally friendly as the electrolyte is water based and easy to recycle,” Dubal said.