活化温度对无灰煤基活性炭结构及性能的影响

以无灰煤(HPC)为原料,KOH为活化剂,采用直接活化法制备无灰煤基活性炭(HAC),并在不同活化温度下探究HAC孔结构的衍化规律。结果表明:活化温度较低时,活化过程表现为无规则碳的烧失,同时微晶单元参与反应,片层明显减小,主要形成0.5 nm以下的微孔,以开孔作用为主。随活化温度的升高,KOH刻蚀微晶结构加剧,以扩孔作用为主,孔径大于0.5 nm的孔居多,同时发展超微孔和中孔。将HAC作为电极材料应用于水系双电层电容器(EDLC)时,其显示出优异的电化学性能,在电流密度为50 mA/g时的比电容达258.2 F/g,在电流密度为5000 mA/g时的比电容保持率在80%以上。研究还发现,EDLC的比电容随HAC电极中0.5 nm^1.5 nm微孔的增加而增大。

Effects of Activation Temperature on Structures and Properties of Hypercoal-based Activated Carbons

With hypercoal(HPC)as the raw material and KOH as the activator,the hypercoal-based activated carbon(HAC)were prepared with direct activation method.The development rule of pore structure of HAC prepared at different activation temperatures was explored.The results show that when the activation temperature is low,it is dominated by random carbon burning and loss.At the same time,the microcrystalline unit participates in the reaction and lamellae significantly reduces.With the activation temperature increases,the microcrystalline structure is etched,mainly by pore expansion.The pore size is gradually dominated by that greater than 0.5 nm,and the ultramicropores and mesopores are developed.As electrode materials with the HAC,EDLC shows excellent electrochemical performance.At the current density of 50 mA/g,the specific capacitance reaches 258.2 F/g.The specific capacitance retention rate remains above 80%at the current density of 5000 mA/g.It is also found that the specific capacitance of EDLC increases with the increase of proportion of 0.5 nm-1.5 nm micropore in the HAC electrode.