GUWAHATI: Researchers from the Indian Institute of Technology Guwahati (IITG) have achieved a breakthrough in super capacitor technology by developing novel materials and methodologies that substantially improve the performance metrics of these energy storage devices. The research, led by Prof. Uday Narayan Maiti of the Department of Physics at IIT Guwahati, has been published in the journal "Small," published by Wiley-VCH.
Super capacitors are energy storage devices similar to batteries but with a key difference: they store energy through the electrostatic field, unlike batteries, which rely on chemical reactions. This enables super capacitors to complete rapid charging and discharging cycles in just seconds, making them ideal for applications requiring bursts of power, such as digital cameras, LED flashlights, and defibrillators used for heart stabilisation.
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However, despite their unique advantages, super capacitors face challenges in widespread commercialisation due to the need to balance three key performance metrics: gravimetric capacitance, volumetric capacitance, and areal capacitance. The latter is crucial for compact and lightweight energy storage solutions, but achieving high areal capacitance often leads to a trade-off with volumetric and gravimetric capacitances.
To address this challenge, Prof. Maiti's team developed a composite electrode using MXene and bio-waste-derived cellulose nanofibers (CNF). MXenes are two-dimensional inorganic materials consisting of thin layers of transition metal carbides, nitrides, or carbonitrides. In this study, the team used a unique electric-field-guided method to assemble these nano materials into electrodes, while CNFs derived from garlic husk were included to improve ion transport and reduce performance trade-offs.
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"These MXene-CNF-hydrogel-derived electrodes exhibit impressively high areal and volumetric capacitance with a very high areal mass loading of more than 70 mg/cm2," said Prof. Maiti. "They maintain 96% of their capacitance after 20,000 charge-discharge cycles, demonstrating robust long-term operational stability."
The researchers achieved this by assembling MXene sheets into porous hydrogel structures and then dehydrating them, resulting in blocked localised pores. The addition of CNFs interconnected the pores, facilitating ion transport and enhancing the super capacitors' overall performance.