Supercapacitors can improve the performance of energy storage devices, especially in terms of cycling life and charging times, says a IIT Mandi Professor.
Researchers at the Indian Institute of Technology (IIT), Mandi, have developed aligned carbon nanotube-based electrodes that could be used in high energy supercapacitors.
Supercapacitors, also known as double-layer capacitors or ultracapacitors, are electronic devices which are used to store extremely large amounts of electrical charge. These devices have considerably higher specific powers and longer cycle lifetimes compared to most rechargeable batteries, such as lead-acid, nickel-metal hydride and Li-ion batteries.
Hence, supercapacitors have attracted research interest worldwide because of the ever-increasing demands of electric vehicles, portable electronic devices and power sources for memory backup.
Viswanath Balakrishnan, Associate Professor, School of Engineering, IIT Mandi, and his research scholar, Piyush Avasthi, have published their research papers in Advanced Materials Interfaces and ACS Applied Nanomaterials.
“A promising route to improving the performance of energy storage devices, especially in terms of cycling life and charging times, is to move away from batteries towards supercapacitors,” Balakrishnan said.
The making of carbon nanotube-based electrodes
A supercapacitor essentially comprises two conducting electrodes immersed in an electrolyte, which are separated by electrically insulating layer to separate the charges, the researchers said in a statement.
While applying the current, potential difference develops between two electrodes and opposite charged ions physically absorb on the respective surfaces of electrodes. This charge storage mechanism is highly reversible, which makes supercapacitors to charge and discharge quickly.
IIT Mandi researcher Piyush Avasthi used a process called Chemical Vapor Deposition to produce ‘forests’ of vertically aligned carbon nanotubes that are wettable (hydrophilic) by the electrolyte.
The perfectly aligned nanotubes, that were a few micrometers in height, were grown on a stainless-steel mesh and treated with two different ways to enhance their hydrophilic properties – in one, the forests were treated with potassium hydroxide (KOH), and in the other, they were coated with an ultrathin layer of titanium dioxide (titania), which made the nanotubes superhydrophilic.
While KOH treatment resulted in better energy density than randomly oriented carbon nanotubes, treating with titania resulted in a 102-fold increase in energy density, 20-fold increase in specific capacitance, and 13-fold increase in power density.
The stainless-steel mesh on which the carbon nanotubes were grown, is physically flexible and would allow incorporation of the energy storage devices on wearable, miniaturized and portable electronic products and smart devices.
(With inputs from India Today)