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Preparation Of Porous Carbon Materials For Supercapacitors And Their Electrochemical Performances

Posted on:2012-07-15Degree:MasterType:Thesis
Country:ChinaCandidate:L TangFull Text:PDF
GTID:2132330332974695Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
As new energy storage device, supercapacitor has become a hotspot for researchers all over the world. And the carbon electrode material is a key factor in deciding the electrochemistry performance of supercapacitor. Based on this consideration, a series of carbon materials with different surface areas and pore structures were prepared by steam activation, template method and solvothermal method. The relationship between the pore structure and electrochemical performance was investigated in inorganic electrolyte (KOH)Activated carbon was prepared by steam activation using coconut shell as precursor at 900℃. Changing the water flow, the sample AC-1.25mL/min exhibit appropriate BET surface area 1325m2/g and maximum total micropore volume 0.5cm3/g. The mass specific capacitance of the activated carbon electrode is 135F/g at 0.1 A/g, and the specific capacitance retention is 79% even at 8A/g.Hollow hierarchical porous carbons with micro/meso/macropores were prepared where resorcinol and formaldehyde were used as precursors, metal organic coordinate polymer (MOCP) as template and Na2CO3 as catalyst. The carbon with specific surface area of 1921m2/g and total pore volume of 1.74cm3/g was prepared with following conditions: MOCP template,3.5g; pre-polymerize temperature,25℃; aging time,5 days. The specific capacitance of the electrode obtained is 155F/g at 0.1 A/g, and the specific capacitance retention is 87% when the current density increased to 10A/g.Mesoporous carbon microsphere (MCM) was synthesized using solvothermal method with glucose as carbon precursor. The specific surface area and total pore volume are 1850m2/g and 1.35cm3/g, respectively. The MCMs were added to commercial super activated carbons (HSAC) to form composites electrodes. The specific capacitance of the composite electrode HSAC-MCM-80-20 is 272F/g at 0.1 A/g. When increasing the current density to 15A/g, it can reach 220F/g and the capacitance retention is 81%. The improvement of electrochemical performance of HSAC at high current density should be attributed to the suitable diameter, mesoporous structure of added MCM, which can decrease the contact resistance of particles and the ion diffusion resistance in the electrode, and then improve the electrode performance at large current densities.
Keywords/Search Tags:supercapacitor, activated carbon, hierarchical porous carbon, mesoporous microsphere, electrochemical characteristics
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