A Wonder Material waiting to Happen

Graphene is an allotropic form of carbon with atoms arranged in a regular hexagonal pattern similar to graphite but in a one-atom thick sheet. Several potential applications for graphene are under development, including lightweight, thin, flexible, yet durable display screens, electric circuits, and solar cells, as well as various medical, chemical, and industrial processes enhanced or enabled by the use of new graphene materials. The most groundbreaking of them all is the production of graphene supercapacitors or electrochemical capacitors.

Researchers claim to have found a way to increase the energy density and turn supercapacitors into a viable alternative for batteries by using electrodes built from graphene, which has shown superior mechanical and electrical properties in the past excellent and apparently revealed electrochemical attributes under high mechanical stress.

Current research suggests that the graphene supercapacitors hold just about as much charge as a normal battery, but they come with a feature that could transform the way gadgets and other battery-driven products such as electric cars and smartphones are used. These are charged and supercapacitors can be discharged a hundred to a thousand times faster than regular batteries.

Metal Oxide-Graphene Composites and Electrochemical Studies is a project led by Umesh Ediga, a Ph.D. scholar in the Department of Chemistry, IIT Madras to tap into the huge potential of the graphene composites. If successful, this project will provide improved methods to modify the electrochemical properties of these compounds, and hence offer insights into their largely unexplored applications.

The Project

The primary objective is to study the capacitance of transition metal oxide graphene composites and improve their conductance and capacitance values, using cyclic voltometry, chrono-potentiometry, impedance spectroscopy and other methods. Umesh intends to calculate the specific capacitance and the ‘poison’ of the catalyst using electrocatalysis studies.

The inspiration for the project was his guide, Mr. G. Rangarao, says Umesh, who suggests the type of metal oxides to be prepared and the methods suitable for each type. Once the data is obtained, Umesh synthesizes the composites and uses X-ray diffraction to determine the particle size of the material. Brunauer-Emmett-Teller (BET) Surface Area Analysis and Thermo Gravimetric Analysis (TGA) and other tests are done on the compounds to get an idea of their chemical and physical properties and their variation with time and temperature, and also their stability. The electrochemical studies are done by Mr. Rajesh Khanna, his partner in the project, who also handles the making of working electrodes and simple calculations.

With an estimated budget of Rs. 5 lakhs, the equipment and other resources required for the project is provided by the labs in liT Madras and also by MNRI. Having a total duration of three and a half years, Umesh undertook this as his Ph.D. project a year and a half ago. So far, Nb 2 0 5 graphene composite has been prepared and tests are being conducted on the same. Plans for the future include preparation of NiCo 2 0 4, Co 3 0 4 and V 2 0 5 graphene composites and data collection and analysis of all the compounds. “What I want to achieve at the successful completion of this project is to come up with new methods to improve the material properties of these composites. This will in turn help increase the cycle life of capacitors and batteries,” Umesh says. On a national scale, similar research is done in IISc Bangalore and various other institutes in the country.

The Impact

The major application of the research is that these compounds can be used to make supercapacitors which are expected to replace batteries in the future. These graphene supercapacitors could transform the technology landscape. While computing power roughly doubles every 18 months, battery technology is almost at a standstill. Supercapacitors, which suffer virtually zero degradation over 10,000 cycles or more, have been cited as a possible replacement for low-energy devices, such as smartphones. With their huge power density, supercapacitors could also revolutionize electric vehicles, where huge lithium-ion batteries struggle to strike a balance between mileage, acceleration, and longevity. It is an interesting fact that lithium-ion batteries have their capacity increased ten-fold just by the addition of graphene. Could graphene be that ‘wonder material’ the world has been waiting for ? Umesh and his team are at the cusp of finding out.

Umesh Ediga is a Ph.D. student at the Department of Chemistry and is guided by Prof G. Rangarao. A day scholar; he enjoys playing cricket and chess.