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Preparation Of Phenolic Resin Based MgO-templated Carbon And Its Application In Supercapacitor

Posted on:2013-03-15Degree:MasterType:Thesis
Country:ChinaCandidate:W J LiuFull Text:PDF
GTID:2232330392452679Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
Supercapacitors, which fill the gap between secondary batteries and the typicaldielectric capacitors, have been recognized as new electrochemical energy storagedevices.They can deliver high energy in much shorter time, cycle more times thanrechargeable batteries and store more energy than traditional capacitors. For theexcellent performance, supercapacitors are widely used in electronic industry, railwaysystem, spaceflight industry, military field and so on. The structures and properties ofelectrode material are decisive for the performance of supercapacitors. Therefore, thestudy of electrode materials is the hot pot for supercapacitors. For idealsupercapacitors, it should have mesopores for the rapid and effective transmission ofelectrolyte ions, besides the existence of micropores.Based on the above depiction, porous carbons rich in mesopores are prepared bychosing MgO crystals, formed during the decomposition of magnesium citrate, astemplate, using thermoplastic (PF(N)) and thermosetting phenolic resin (PF(R)) ascarbon precursors. The porous carbons, marked as MCPF(N) and MCPF(R) accordingto the carbon precursors, were then applied as electrode material for supercapacitorswith aqueous electrolytes.In the carbon system of MCPF(N), carbon MCPF(N)82got the highest BETsurface area,1920m2·g-1, and MCPF(N)46got the biggest mesopore ratio,88.60%.Compared with MCPF(N), MCPF(R) system got the smaller result of BET surfacearea and mesopore ratio. Sample MCPF(R)82got the biggest mesopore ratio,1722m2·g-1; sample MCPF(R)73got the biggest mesopore ratio,82.33%. Pore structures ofMCPF(N) system were determined as ink-bottle-like geometry through TEMcombined with N2adsorption analysis, and the porous carbons of MCPF(R) systemwere determined to be slit pores with parallel-plate.The porous carbons prepared were then applied as electrode material forsupercapacitors. The capacitor performance was examined in30wt%KOH aqueoussolution by cyclic voltammetry and galvanostatic charge/discharge measurements.The capacitances of the two carbon systems at different current densities are found tobe increase with growing BET surface area. The carbon MCPF(N)82exhibited a capacitance of221F·g-1at a current density of50mA·g-1, and carbon MCPF(R)82gotthe capacitance of186.8F·g-1. Besides, the rate performances of the two carbonsystems were found to be following the same trend with mesopore ratio. The twoparameters both increased firstly then decreased with growing MgO:PF mass ratio.The carbons MCPF(N)46and MCPF(R)73got the rate performance of98.3%and89.4%, individually, expressed as the ratio of the capacitance measured at1000mA·g-1against that at50mA·g-1.
Keywords/Search Tags:supercapacitor, electrochemical performance, template, mesoporous carbon, pore structure
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