Though carbon is widely used, they still face a major drawback of poor specific capacitance compared to that provided by conducting polymers 31 and metal oxides 32, 33 as Faradaic reactions occur in these materials. Activated carbons employed as electrodes for supercapacitors are usually obtained from renewable resources, biowastes, sawdust, neem leaves, coconut shell, bamboo, see weeds etc 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. Activated carbons usually possess higher porosity, high chemical and thermal stability, surface area and packing density 19, 20. Among the carbonaceous materials used in literature, ACs has outstood the others. Thus various carbonaceous materials such as activated carbon (AC) 3, graphene 10, metal carbide derived carbon 11, ordered mesoporous carbon 12, 13, carbon aerogels 14, 15 and carbon composites 16, 17, 18 have been tested for their supercapacitive behavior. It is well known that carbonaceous materials possess highest surface area compareg to metal oxides/sulfides/phosphides 6, 7, 8, 9. The surface area of the electrode material used is of utmost importance in this type of supercapacitor 3, 5. In EDLC based supercapacitors the charges are stored based on the double layer formation happening at the electrode surface. Typically supercapacitors can be classified into three types based on the mechanisms of charge storage: (1) Electrochemical double layer supercapacitors (EDLC),(2) Pseudocapacitors and (3) hybrid supercapacitos 3, 4. Thus significant research in exploring new electrode materials to obtain improved performance is being progressed. The most critical component in a supercapacitor is the electrode material used, which determines the ultimate performance of the fabricated supercapacitor. With careful selection of electrode material and with the use of simple, cost effective synthesis techniques, supercapacitors can be developed for commercial applications on a larger scale. A rapid charge storage mechanism is observed in case of supercapacitors, attributing to their decreased charging time, improved cyclability and thereby capacitance 3. However the power density exhibited by supercapacitors is less compared to conventional capacitors but with improved energy density 1, 2. Whereas batteries possess high energy density to that of supercapacitors with low power density. Electrochemical supercapacitors possess high power density with respect to batteries but suffer from poor energy density. It is quite well known that both the devices have their set of advantages and drawbacks. In this regard, lithium ion batteries (LIBs) and electrochemical supercapacitors (SCs) have recently gathered a huge attention. The market for small portable electronics and hybrid electric devices is fast-growing thereby demanding an immediate supply of developed storage systems of electrochemical energy. Overall, this work provides an in depth analysis of the science behind the components of an electrochemical energy-storage system as well as why the different characterization techniques are required to assess the quality and reliability of the material for electrochemical supercapacitor applications. ![]() A detailed analysis is done to correlate the results obtained with the material property. ![]() ![]() KOH-activated hard carbon has provided 479.23 F/g specific capacitance as calculated from its cycle voltammograms. Four different hard carbons were synthesized from KOH activated banana stem (KHC), phosphoric acid treated banana stem derived carbons (PHC), corn-cob derived hard carbon (CHC) and potato starch derived hard carbons (SHC) and tested as supercapacitor electrodes. A cheap, eco-friendly and easily synthesized carbon material is utilized as electrode for electrochemical energy-storage. This work is based on a simple synthesis route of biomass derived hard carbon and to exploring the possibility of using it as electrochemical supercapacitors. Limited resources also force to innovate something that can utilise the resource more efficiently. As the resource of fossil fuel is draining out fast, an alternative is always required to satisfy the needs of the future world. With every moving day, the aspect that is going to be the most important for modern science and technology is the means to supply sufficient energy for all the scientific applications.
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