Assam: IITG develops high-performance materials for supercapacitors
Guwahati: Researchers from the Indian Institute of Technology Guwahati (IIT Guwahati) have developed novel materials and methodologies that significantly enhance the performance metrics of supercapacitors.
Led by Prof Uday Narayan Maiti of IIT Guwahati’s Department of Physics, the team of researchers also included Pradip Kumar from Bhopal’s Council of Scientific and Industrial Research (CSIR)-Advanced Materials and Processes Research Institute (AMPRI), and Narayanan Padma from Mumbai’s Bhabha Atomic Research Centre (BARC).
Supercapacitors, akin to batteries, serve as energy storage devices. However, unlike batteries that rely on chemical reactions, supercapacitors store energy through the electrostatic field - the separation of charges. Renowned for their remarkable efficiency, supercapacitors can complete rapid charging and discharging cycles in mere seconds.
Powering quick-charging devices such as digital cameras and light-emitting diode (LED) flashlights, supercapacitors boast charging times as short as 90 seconds.
They prove indispensable in applications requiring bursts of power over short periods, such as defibrillators used for heart stabilisation and power stabilisation in devices like laptops.
Despite their exceptional energy storage properties, supercapacitors face challenges in widespread commercialisation.
For any supercapacitor technology to achieve commercial success, it must simultaneously meet three critical performance metrics - gravimetric capacitance, volumetric capacitance and areal capacitance.
Areal capacitance is particularly crucial for designing compact and lightweight energy storage solutions.
However, achieving high areal capacitance necessitates large amounts of energy-storing active materials for the electrodes, resulting in a trade-off with volumetric and gravimetric capacitances.
To tackle this challenge, Prof Maiti’s team of researchers introduced a composite electrode comprising MXene and bio-waste-derived cellulose nanofibers (CNF).
MXenes represent two-dimensional inorganic materials comprising extremely thin layers of transition metal carbides, nitrides or carbonitrides.
In this study, the team used a novel electric-field guided method to assemble these extremely thin and small nanomaterials to form the electrodes. Nanofibers, on the other hand, are filaments that are 100,000 times thinner than human hair.
These nanofibers were strategically included to overcome the performance trade-off with very high mass-loading electrodes.
“These MXene-CNF-hydrogel-derived electrodes exhibit impressively high areal and volumetric capacitance with very high areal mass loading more than 70 milligrams per square centimetre (mg/cm2). They maintain 96 per cent of their capacitance after 20,000 charge-discharge cycles, showcasing robust long-term operational stability,” Prof Maiti said in his research.
The researchers assembled MXene sheets into porous hydrogel structures, gels that retain a significant amount of water.
They found that dehydration of these hydrogels resulted in the creation of blocked localised pores.
The introduction of CNFs derived from garlic husk interconnected the pores and facilitated ion transport.
Practical supercapacitors boasting high aerial, volumetric and gravimetric capacitance hold promise for applications in electric vehicles, renewable energy systems and consumer electronics, heralding significant advancements in energy storage technology.