The Preparation Of Continuous Porous Carbon Network And Its Supercapacitor Performances

Environmental pollution problems triggered by the energy crisis have become more and more seriously. People urgently demand the development of new energy device. Although the new generation of li-batteries have a higher performance in capacitance and working life than its previous one, they can not satisfy the demands in daily life. Supercpacitors which are new type of energy device have more advantages than li-batteries, such as higher power densities, higher charge discharge efficiency, lower leek current, maintenance-free, environment friendly. Some advanced carbon materials such as graphenes, carbon nanotubes, carbon nanofibers have been deeply investigated in decades as supercapacitor electrode materials. Although these carbon materials have shown great power densities and superior performance, their defects such as high cost, complicated preparation process, catalysts in use during the manufacturing have limited their widely use. For the maximal economic interests, carbon materials prepared from sustainable sources such as biological components would be an effective way to achieve the conversion from low value carbon sources to high yield product.Biological materials are solid, practical, slinky biological tissues which created by biology with least raw materials. The biological materials have the advantages of peculiar, odd, subtle. Moreover, Biomimetic materials are a kind of artificial materials with superior performance. Hence, carbon materials prepared from sustainable sources such as biological components would be an effective way to achieve high yield product. In this thesis, we obtain a unique3D mollusc-shell-derived carbon materials via simple decalcification and carbonization process from natural mollusc shell, No any nocuous oxidations and catalysts in use during the whole manufacturing operation makes mollusc shell derived carbon materials environment friendly and great benefit to large scale application in clean energy storage. And then employ these carbon materials as template to form3D carbon network@metal oxide (hydroxide) composite as supercapacitor electrode. The obtained composites exhibit exceptional electrochemical performance. The main contents showed as follows:(a) We have prepared3D carbon network@Ni(OH)2nanosheets composite and characterized the morphology. The capacitance performance of obtained composite has deeply evaluated by a function of electrochemical tests. The specific capacitance is1312F/g,970F/g at the current density of1,10A/g, respectively. The capacitance still exhibits864F/g,807F/g,778F/g,730F/g when the current density increases to15A/g,20A/g,25A/g,30A/g, demonstrating excellent supercapacitor performance. Such excellent carbon network derived from mollusc shell has never been reported for energy storage applications in previous works. Symmetric solid-state supercapacitors based on3D carbon network@Ni(OH)2nanosheets composite has shown excellent performance, two tandem capacitor can effortlessly lighten a red LED light for270s after charging at2A/g for40s.(b) We have used3D carbon network as template to prepare3D carbon network@Co3O4nanocube composite. The capacitance performance of obtained composite has deeply evaluated by a function of electrochemical tests, The calculated specific capacitance is817F/g,720F/g,640F/g,614F/g,542F/g at the current density of1A/g,2A/g,4A/g,10A/g respectively. The capacitance of the symmetric capacitor also retained86%after over1000cycles demonstrating excellent supercapacitor performance.(c) We have prepared3D carbon network@MnO2nanowire composite. The capacitance performance of obtained composite has deeply evaluated by a function of electrochemical tests, The calculated specific capacitance is335F/g,235F/g,175F/g,125F/g at the current density of0.5A/g,1A/g,2A/g,4A/g respectively, demonstrating excellent supercapacitor performance and superb affinity between3D carbon network with transition metal compounds.