Lithium, sodium, potassium and magnesium batteries:

Among various rechargeable batteries, lithium-ion batteries occupy a special place in terms of energy density and also several applications anticipated. Research activities on important electrode active materials have been under progress. Positive electrode materials, which are capable of providing high specific capacity with good structural stability over prolonged charge-discharge cycle life, are considered important for future generation lithium-ion batteries. Electrochemical cells in non-aqueous electrolytes are assembled in an argon filled glove box and evaluated for various electrochemical properties. The properties include specific discharge capacity, rate capability, temperature dependence on capacity, ac impedance behavior, diffusion coefficient and cycle-life test. Li-O2 battery has energy density which is comparable to gasoline. Bifunctional catalysts for oxygen electrode reactions in rechargeable Li-O2 and Na-O2 cells are investigated. The global raw material resources of Li are limited and they are available unevenly on the earth. As a consequence, it is likely that a lithium crisis will be seen affecting production of Li-based rechargeable batteries for large scale applications such as electrical vehicles. Rechargeable batteries based on Na and K are expected to be viable substitutions for Li based batteries. Research activities are in progress on several electrode materials, which provide high specific capacity, cycling stability, long cycle-life etc.


Electronically conducting polymers are interesting class of materials studied for supercapacitor application because of the following merits: high electronic conductivity, environmental friendliness, ease of preparation and fabrication, high stability, high capacitance and low cost. Polyaniline and poly(3,4-ethylenedioxythiophene) are studied in this category. Among the transition metal oxides, MnO2 with a theoretical specific capacitance of 1370 F g-1 is an attractive material for supercapacitor studies. However, a maximum specific capacitance of about 240 F g-1 is usually reported in the literature. Attempts are made to enhance specific capacitance of MnO2 by electrochemical deposition in presence of surfactants. Nano-structured MnO2 synthesized by inverse microemulsion route is also studied for electrochemical supercapacitors. The effect of crystallographic structure of MnO2 on the capacitance properties, studies on electrochemical deposition of MnO2 in acidic and neutral medium using electrochemical quartz crystal microbalance and capacitance characteristics of MnO2-polyaniline composites are studied.

Electrochemical and photoelectrochemical water splitting:

Water splitting is a promising method for hydrogen production. It requires 237 kJ mol-1 of energy, which corresponds to a voltage of 1.23 V. However, commercial electrolyzers usually operate between 1.8 to 2.1 V, indicating the necessity of large overvoltage. The high overvoltage and subsequent energy loss are mainly associated with the sluggish kinetics of oxygen evolution reaction (OER) at the anode. We are interested in the design, development and activity analysis of various transition metal based OER catalysts. It is found that electrochemically deposited cobalt-acetate, manganese-phosphate, iridium-phosphate etc. show high activity towards OER. Also investigations are in progress on photoelectrochemical water splitting.

Conducting polymers:

Electrochemistry of conducting polymers is an important area of research in view of various applications. Electrooxidation of methanol, formic acid, formaldehyde and ethanol on nanocluster of Pt and Pt-Ru deposited on PEDOT/C electrode are studied in view of their promising applications in fuel cells. Films of PEDOT are electrochemically deposited on carbon paper. Nanoclusters of Pt and bimetallic Pt-Ru catalysts are potentiostatically deposited on PEDOT/C electrodes. Catalysts are also prepared on bare carbon paper for studying the effect of PEDOT. The presence of PEDOT film on carbon paper allows the formation of uniform, well dispersed nanoclusters of Pt as well as Pt-Ru catalysts. TEM studies suggest that the nanoclusters of about 50 nm consist of nanoparticles of about 5 nm in diameter. Electrooxidation of methanol, formic acid, formaldehyde and ethanol are studied on Pt-PEDOT/C and Pt-Ru-PEDOT/C electrodes by cyclic voltammetry and chronoamperometry. The data for oxidation of these small organic molecules reveal that PEDOT imparts a greater catalytic activity for the Pt and Pt-Ru catalysts. PEDOT - coated stainless steel electrodes are used to investigate phenol oxidation and also for supercapacitors studies.

Representative Publications