Investigation On The Prepraration, Characterization And Capacitance Properties Of Modified-phenolic Base Activated Carbons

As an intermediate power source between conventional capacitors andrechargeable batteries, supercapacitors have attracted considerable attentiondue to their advantage of wide range of energy storage, long cycle life andavailable thermal stability at-40. Electrode is the key part ofsupercapacitors. Activated carbons are regarded as one of the best electrodematerials of supercapacitor because of their high specific surface aera andpore volume. Therefore, the preparation of activated carbons is essential forthe properties of supercapacitors. In this thesis, activated carbons with highspecific capacitance and yield coefficient were prepared successfullythrough polymer blend carbonization method using low-cost phenolformaldehyde (PF) as matrix.(1) The phenolic base activated carbon materials were synthesized bypolymer blend carbonization method using phenol formaldehyde as carbon matrix. The effects of the types of pore former and solvent, carbonizationtemperature, and content of polyethylene glycol (PEG) on the yield ofactivated carbons and the adsorption properties of iodine were investigated.The results showed that the activated carbons prepared using PEG as poreformer and acetone as solvent possessed superior yield of activated carbons(49.28%) and adsorption properties of iodine (417mg/g) when thecarbonization temperature and the content of PEG were600℃and1/6,respectively. In addition, the effects of carbonization temperature andcontent of PEG on the properties of constant current charge/discharge andspecific capacitance of activated carbons were also studied. It was shownthat the specific capacitance of activated carbons reached38.5F/g whenthe carbonization temperature and the content of PEG were600℃and1/3,respectively.(2) On the basis of polymer blend carbonization method, the activatedcarbons used for supercapacitors were activated by steam subsequently.The influence of activated temperature, flow rate of steam, and activatedtime on the structure and properties of activated carbons were explored.The results showed that the three factors mentioned above exerted aninfluence on both the structure and properties of activated carbons. Theoptimal conditions to prepare activated carbons were using PEG6000aspore former and acetone as solvent and controlling the carbonizationtemperature at600℃and the content of PEG at1/6. When the activated carbons carbonized at600℃for2h in the steam with flow rate at1.0ml/min, the yield of activated carbons was23.38%. The specificcapacitance of activated carbons decreased from116.7F/g to108.0F/gwhen the scan rate increased from50mA/g to500mA/g. Meanwhile, thecapacitance retention was92.5%. The large current charge/dischargeproperty was good. The nice triangle symmetry was obtained in theconstant current charge/discharge curve. The capacitance retention was99.2%when cycled2100cycles, which displayed that the preparedsupercapacitor electrode materials activated carbons possessed nice cyclingstability.