Synthesis of layered vanadium oxides and development of composite cathodes using various carbon additives
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There has risen a need to find alternate energy sources to replace coal and fossil fuels as the current sources of power and energy. Also, the miniaturization of modern day electronics has boosted interest in energy storage devices. For these reasons there are many battery systems which are being researched. One of the more prominent technologies of these has been Li-ion batteries. In these there has been tremendous focus on the development of a cathode material in the field of Lithium ion batteries which can allow for good Lithium ion intercalation. For this a material with high theoretical capacity and low cost is needed. However, these materials are inherently non-conductive in nature. We thus need to add various conductive additives to the cathode material to make it better suit the application. Carbon additives have been predominantly used for improving the electronic conductivity of materials. The conductivity of the carbon has been explained using the valence band theory which states the free electrons present in the d orbital of the valence band present free electrons which help in conductivity. Both Carbon additives such as Acetylene Black/Ketjen Black and Carbon nanotubes have been used as additives. These materials lower the overall density of the composite cathode but increase the overall conductivity tremendously. Lower density however also is important for high power applications and as it facilitates diffusion. Of these Carbon nanotubes are also known to exhibit better mechanical, thermal and electrical properties as compared to other forms of carbon. They have shown low mass density, low resistivity and large surface area. Studies regarding the incorporation of Carbon nanotubes into the cathode material are being widely studied at present and there have been many cases which have reported improved rate performances and extended cycle life of the battery. However, there is also a need to add other carbon additives such as Ketjen Black as these carbon fillers result in the enhancement of the electrical and thermal properties of the electrode as well as the lowering of the overall density. They also lessen the electrolyte absorption time.