Design Of Porous Carbon Materials And Their Superior Performance In Electric Double-layer Capacitor

Energy crisis and environmental pollution are two major problems that restrict the global development.It is a significant way to realize sustainable development with research and development of a clean energy storage technology.Electric double-layer capacitors(EDLCs)possess the advantages of wide voltage window,good circulation stability,high power density,fast charge-discharge rate and environmental protection,which have become promising energy storage devices.The charge storage mechanism is the double electric layers formed on the electrode-electrolyte interface.Although porous carbons with large specific surface area,complex pore structure and excellent chemical stability are the most commonly used electrode materials,they also often affect the electrochemical performance due to uneven pore size distribution,poor electrical conductivity and narrow working voltage window.Therefore,it is a significant topic to modify carbons through appropriate means to obtain better capacitor performances.In this paper,two different carbon precursors were used to synthesize porous carbon materials,whose specific surface area,pore size distribution,conductivity,wettability or voltage window were modified by different ways to obtain better electrochemical performance.The main contents and conclusions are summarized as followings:(1)A nanosized graphitic carbon with balanced and interconnected micro-mesopores is prepared by directly carbonizing Ni(II)exchanged resin.The homogeneously dispersed Ni nanoparticles well act as the catalyst for in-situ graphitization of low-cost resin and porogen for the formation of configured micro-and mesopores.The graphitized carbon GC-800 exhibits a balanced micro/mesoporosity at the ratio of 1:2,which delivers an excellent specific capacitance 66.0 μF/cm2 at current density of 0.5 A/g in the electrolyte of 1.0 M H2SO4 and a high energy density of 7.43 Wh/kg at a power density of 125.0 W/kg in the dual-electrode system.Furthermore,the electrode material GC-800 have remarkable cyclic stability via floating technology(95%,400 h)and GCD testing technology(~110%,10,000 times)and low resistance and good rate capability.(2)An oxygen-doped porous carbon material is fabricated from biomass-derived seaweed via a facile and low-cost Na Cl activation process.The prepared sample Na Cl SC-800 not only has a specific surface area of 329.3 m2/g,but also a matched microporous structure(0.8 ~ 2 nm)with the electrolyte(1 M H2SO4),showing a good electrochemical performance.In the three-electrode system at a current density of 0.5 A/g,the sample Na Cl SC-800 exhibits a high specific capacitance of 324 F/g(98.5 μF/cm-2).In the two-electrode system,the sample Na Cl SC-800 with O content up to 20% can reach a wide voltage window of 1.4 V and obtain a high energy density of 15.9 Wh/kg at a power density of 175 W/kg.Besides,it also exhibits an excellent cycle stability(98%,10000)and good rate performance.