Preparation Of Active Carbon Foam Based On Coal And Used For Study On Supercapacitor Performance

Prepared by carbonization using loose medium component which was separated from raw coal by all-components group separation, semi-carbon-foam was chosed as raw material to apply to prepare active carbon foam under potassium hydroxide and steam active method. The influences of active temperture, active time, solution concentration, soaking way, adding CaO solid powder under potassium hydroxide active method, and active time, shape of semi-carbon-foam under steam active method, et al. on pore structure of active carbon foam were inspected, respectively. According to electrochemical performance test, association between pore structure and electrochemical performance was focused to explore. Bsides, preparing process of active carbon foam, electrode slice, and assembling prcess of supercapacitor were optimized.The results showed that the active carbon foam prepared by steam active method has low level on total specific area and pore volume; powdery semi-carbon-foam can destroy the abundant foam pore structure and increase its bulk density thus lead to ineffective activation. The more effective active method, KOH active method, can prepare out high total specific area and high total pore volume sample under vacuum heating after soaking or adding CaO; the peak position of pore size distribution is quite similar; within limits, higher ative temperature lets total pore volume increase at first then decrease, longer active time leads to increase total specific area, and larger mass percentage of potassium hydroxide soltion makes total specific area and pore volume increase at first then decrease.Active carbon foam with three types of hierarchical pores(named mountain type stair-stepping, peak type stair-stepping, and dispersed distribution) are prepared out. Thereinto, when the total specific area of a sample beyond 2300 m2/g and it has mountain type stair-stepping pore distribution, its specific capacitance will be very high(220~240 F/g under 25 mA/g). The reason is its high stair-stepping pore distribution can not only provide high specific area which can supply adequate energy stored space, but also offer continuous variable and more aperture to reduce the resistance of ion transfer. There are high degrees of linear correlation between specific capacitance and pore structure parameters in 1.54~2.53 nm and 2~5 nm of samples with stair-stepping pores distribution(Radj2 around 0.9); considering comprehensive pore size distribution character, There are still high degrees of linear correlation between them in 1.54~2.53 nm of samples with stair-stepping pores distribution(Radj2=0.898), and if the pore size range is contracted or expanded, the Radj2 will decrease. According to preparation and assemblying method optimization, CACF-3 gets the highest specific capaci-tance reached 282.39 F/g(at 25 mA/g) when the electrode slice is not soaking.