IIT Guwahati develops hydrogel based electrodes to increase performance of supercapacitor devices.
As a building block of the hydrogel, the team chose two different kinds of nanosheets, namely graphene and MXene, which store charge via two different mechanisms.The results of the breakthrough work in collaboration with Bhabha Atomic Research Centre BARC, Mumbai has been published in journals -- Electrochimica Acta and Carbon recently.Most important aspect of this development lies in its extreme simplicity, scalability and mainly room temperature process which prevents the temperature sensitive MXene from changing its conducting property which ensures high device performance, said Uday Narayan Maiti from Department of Physics, IIT Guwahati.
A hydrogel is a porous framework of interconnected materials, in which water remains stably locked within the pores. As a building block of the hydrogel, the team chose two different kinds of nanosheets, namely graphene and MXene, which store charge via two different mechanisms.
The results of the breakthrough work in collaboration with Bhabha Atomic Research Centre (BARC), Mumbai has been published in journals -- ''Electrochimica Acta'' and ''Carbon'' recently.
''Most important aspect of this development lies in its extreme simplicity, scalability and mainly room temperature process which prevents the temperature sensitive MXene from changing its conducting property which ensures high device performance,'' said Uday Narayan Maiti from Department of Physics, IIT Guwahati. ''The entire process of hydrogel development is like constructing a large building with bricks as building blocks. However, development of hydrogels for energy storage using nanosheets require multi-level tuning starting from electronic properties, surface chemical properties and mutual interactions.
''In our hydrogel structure large graphene sheets provide mechanical stability to the hydrogels, whereas synergistic electronic properties of graphene and MXene give excellent energy storage performance. We believe this development can serve as a platform for further exploration in the area of energy storage devices and beyond,'' he added.
According to the three member team, in Supercapacitors two electrodes (anode and cathode) made of suitable materials are immersed within electrolyte solution, and energy is stored by charge accumulation on the electrode surfaces. Atomic-thin sheet-like materials, known as nanosheets, are considered as the best choice for supercapacitor electrode as they can offer a large area to store charge. However, integrating microscopic ultra-small nanosheets into usable macroscopic scales is highly challenging.
The researchers developed the hydrogels electrodes by simple room temperature process in which graphene and MXene spontaneously assemble themselves over metal plates within a water medium. ''This unique structure can avoid the restacking challenge associated with charge-storing nanosheets. Graphene, a single atom thin carbon sheet, stores charge on its surface via physical adsorption, known as electrical double layer mechanism (EDLC). Whereas, MXene, nanosheets of titanium carbide, stores charge via both EDLC and chemical reaction on its surface, known as pseudo-capacitance ''Importantly, these supercapacitors can deliver the energy at a very fast rate when required, which is presented in terms of power density. They have achieved a highest power density of 1.13 kW per kg of electrode material which is almost twice the power offered by current Li-ion batteries. Their hydrogel devices can be engineered to be compact enough to fit the extreme tight spaces of modern portable electronics, which is gaining increasing popularity among the masses,'' he said.
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