Fabrication of Symmetric and Asymmetric hybrid Super Capacitors based on Nano sized metal oxides, conducting polymers and Carbon derivatives, synthesized using Field Assisted Pulsed Laser Ablation in Liquid Technique

The use of renewable energies as the major sources of energy has become a top most priority for many developed countries in the world. The main reason for this is that the fossil fuels will not be available in future for increasing population and also the continuous use of these fuels is causing serious environmental problems like global warming and climate change. Harvesting energy directly from the source is one thing but to store it for the later use is also another challenging task. Most of the research in the field of renewable energy is focused on storing the energy in the form of batteries and other devices. Although the batteries are working fine but they lack high power density. There are many applications in our routine life when we need higher power peaks and fast switching for example lifting something with crane or driving an electric car in hilly area or need high performance in electronics. The use of battery alone in such cases is not enough, so we have to look for a device which can provide high energy density like a battery along with high power density. The only device which can perform both things is super capacitor or hybrid super capacitor. The research on super capacitor has emerged significantly in the last decade because of the understanding of the charge storage mechanism inside of the capacitor and development of new types of nano structures. Super capacitors fabricated using porous active carbon and its derivatives are called electrochemical double layer capacitor (EDLC). Charges are stored electrostatically between active material and electrolyte interface. In order to get large capacitance, the surface area of the active material should be large. Another type of super capacitor that uses metal oxides and conducting polymers as active material is called pseudo capacitor. Charges are stored by reversible redox reaction in this case and hence exhibit large capacitance value. Scientists are also working on mixing these capacitive electrodes with battery type electrodes to increase the energy density along with power density to fulfil the future energy demands. In order to fabricate a super capacitor, a paste of nano material is prepared and then applied on current collectors to make film. There are many ways to synthesize nano particles but each has its own limitations. Nano synthesis by gas-phase method produces agglomeration causing non homogeneous dispersion. Also chemical methods for the nano synthesis are widely used but purity of the nano material is at stack because of the precursors used. In compare to these methods, pulse laser ablation in liquid (PLAL) has achieved great attention during the past years. Because it does not require any special conditions of temperature and pressure and has no harmful effects on the environment. The nano particles synthesized using this technique, are also stable and pure. The novelty of the proposed work is to grow thin films directly on to the current collectors using the method of pulsed laser ablation in liquid (PLAL). In literature we have not found the fabrication of super capacitors using this method, to the best of our knowledge. In order to optimize the particle size, deposition, and ultimately the performance of the super capacitor, we introduce optimum electric and magnetic field in PLAL process which is quite novel and result oriented. We expect to get new shapes of nano particles with different pore size which could yield high energy density and improved capacitance.