STUDY OF METAL OXIDES/CNTs COMPOSITE BASED ELECTRODES FOR APPLICATION IN ASYMMETRIC SUPERCAPACITOR

Abstract

Supercapacitors are the new generation energy storage device with very high power density, of the order 20 1KW/kg and capacitance of 310 FIg and energy density of the order of 50 W-h/kg. With the energy density of 100-150 W-h/kg, the lithium ion batteries still lead the market of energy storage device. 1-lowever its power density is so low that it cannot he used in high power applications such as heavy duty motors, electric vehicles etc. Supercapacitors are favorable for such applications because of their ability to provide high power in a very short duration. Also they have a very high cycle life of more than 10000 cycles at 100% load and very fast charge-discharge ability. World over efforts are on to increase the energy density of supercapacitors. The recent development in Nanotechnology has led, to the development of smart materials which shows enhanced electrochemical and electronic properties and is suitable to be used in supercapacitor material to improve upon its capacitance, energy and power density. Carbon nanotubes have emerged as an excellent anode material for supercapacitors with specific capacitance as high as 350 F/g. These materials store electric charges in electrostatic field i.e. in electrical double layer rather than in chemical state as in batteries. Scientists have developed an asymmetric supercapacitor which uses different kind of materials as anode and cathode. The anode material being of CNTs and the cathode being made of material such as transition metal based oxides, silicates, phosphates etc which store charges by faradaic chemical reactions, the one which is used in batteries. Thus Scientists have been able to considerably increase the energy density ol' Supercapacitors up to 100 W-h/kg by such asymmetric supercapacitors. So there is a wider scope to use nanostructures in these energy storage materials to improve upon its performance.