Control Synthesis And Electrochemical Performance Of Porous Carbon Based On Metal Complex As Precursor

Supercapacitors are a new type energy storage device between conventionalcapacitors and secondary battery. Specific capacitance is superior to the traditionalbattery; power density is superior to the secondary battery. It is an energy storage andutilization device of good application. The characteristics of the electrode materialdetermine the electrochemical performance of electrochemical capacitors; therefore,high–performance materials research in this area has been the focus of attention.Choosing special methods and carbon sources can get excellent electrochemicalproperties of electrode material.This paper uses the template carbonization to prepare the porous carbon materials,by changing the type of carbon source, carbonization temperature, carbonization timeand nitrogen-doping amount to get the control purposes of carbon materials of specificsurface areas, total pore volume and pore structures. The main content of the paper areas follows:1. Porous carbons have been prepared by a direct carbonization method, without anyphysical/chemical activation process, using sodium/potassium tetraphenylborate ascarbon sources. It reveals that the carbonization temperatures, and tetraphenylboratespecies play crucial roles in determning the structures, including surface areas, porevolumes and pore size distributions. The carbon-K-900sample has a high surface area836m2g–1and large total pore volume0.86cm3g–1. The resultant electrochemicalperformances were deeply studied by a two-electrode system and a three-electrodesystem, using KOH and1-ethyl-3-methylimidazolium tetrafluoroborate (abbr.[EMIm]BF4) as electrolyte, respectively. The carbon-K-900sample displays specificcapacitance of281.0F g–1at1A g–1in a three-electrode system, using KOH aselectrolyte, whilst those of208.4, and295.6F g–1at1A g–1can be achieved in atwo-electrode system, using KOH and [EMIm]BF4as electrolyte, respectively. Thecarbon-K-900sample also exhibits good rate capability and cycling durability. Moreimportantly, we intensively investigated the effect of operation temperature such as25/50/80°C upon the capacitive performance of the carbon-K-900sample. It indicatesthat introducing ionic liquid into supercapacitor as electrolyte can greatly extend theoperation temperature and higher operation temperature indeed favors for gainingbetter capacitive performance in present work.2. Flake-like porous carbon has been synthesized by the carbonization of aluminium salicylate coordination polymer, in which the precursor serves as the hard template andcarbon source. Interestingly, the flake-like morphology of the original coordinationpolymer is retained after the carbonization and subsequent washing process. It revealsthat the carbonization temperature plays crucial impact upon the specific surface area,pore structures and capacitive performances. The carbon-900sample exhibits themaximum BET surface area and total pore volume as1162m2·g-1and0.80cm3·g-1,respectively. Meanwhile, the carbon-900sample has the specific capacitance of220.0Fg-1at a current density of0.5A g-1and that of193.7F g-1at1.0A g-1, as well as the highenergy density of ca.30.5Wh/kg at a power density of ca.0.25kW/kg. Furthermore,the carbon-900sample can possess a high retention as88.57%within3000cyclestowards, indicating its long-term cycling stability.3. Highly luminescent zinc(II)-bis(8-hydroxyquinoline)(Znq2) coordination polymerwas successfully prepared at room temperature, using Zn(NO3)2·6H2O and8-hydroxyquinoline (8–HQ) as starting materials, and the Znq2powder dissolved inabsolute ethanol can act as selective luminescent probes for the detection andquantification of heavy metal ions. Since the formation of coordination polymers specialstructure and pore size distribution, synthesis of porous carbon have special structureand excellent performance.Additionally, solvothermally treating the Znq2powder canengender carbon precursors, which was further heated800oC with CO(NH2)21:10/1:20/1:30or without to produce nitrogen-doped/undoped porous carbon. It revealsthat the mass ratio of carbon precursors and CO(NH2)2can exert a decisive impact onthe nitrogen species, dopant dosages as well as specific surface areas and pore structures.It can get the best porous carbon when the mass ratio of carbon precursors andCO(NH2)2is1:20. The specific capacitances of carbon-N-1:20samples measured at thecurrent density of1A·g–1are219.2F·g–1, the carbon-N-1:20exhibits good capacitanceretention as45.2%at20A·g–1as well as cycling stability (ca.6.5%loss after3000cycles).4. Sodium sulfanilate and magnesium acetate are carbonized at800o C in the ratioof1:0,1:1,1:3after grinding in order to get the porous carbon materials. It reveals thatthe carbonization temperature plays crucial impact upon the specific surface area, porestructures and capacitive performances. It displays good performance of porous carbonmaterials at the ratio of1:3. Magnesium acetate has played a template role at a highcarbonization temperature, and plays the role of pore-forming in the synthesis ofporous carbon materials. Meanwhile, the carbon-1-3sample has the specific capacitance of180.0F g–1at a current density of1A g–1. And after5000cycles,carbon-1-3can possess a high retention as93.0%within3000cycles, indicating thegood cycling stability. It can be widely used in the synthesis of porous carbonmaterials.In addition, we use sodium alginate and calcium acetate to prepare porous carbonmaterials used a high carbonization temperature for for electrochemical capacitors.Sodium alginate and calcium acetate are carbonized at800o C at the ratio of3:1,1:1,and1:3to obtain different porous carbon materials. Different carbonizationtemperature and ratio will result in different pore structure, surface area, andelectrochemical properties. We can get porous carbon of best electrochemicalproperties and reasonable pore size distribution at the ratio of1:1. The specificcapacitances of carbon-1-1are160.0F·g–1at the current density of1A·g–1.It has along-term cycling stability after5000cycles of maintain rate about94%. So selectingsodium alginate as a carbon source and calcium acetate as a template, we can prepareexcellent performance porous carbon materials.