摘要
以椰壳为原料,ZnCl2为活化剂,用同步物理-化学活化法制备活性炭。所得的炭样品用氮吸附法表征,并根据77K时的吸附-脱附等温线计算了它们的比表面和孔结构参数。用恒流充放电和循环伏安法研究了由活性炭电极与KOH电解质构成的双电层电容器的性能。结果显示,在5mA时放电,活性炭比电容最高达到360F/g;在大电流50mA时,比容量仍超过200F/g。同时分析研究了炭材料比表面积和孔径对电化学性能的影响,发现比表面积与比电容关联性不明显;而孔径大小对炭材料的比电容影响很大。在小电流放电时,中孔炭表面对比电容的贡献明显大于微孔炭表面;随着放电电流的增加,由中孔炭表面构成的双电层电容下降显著,而微孔炭表面的双电层电容下降幅度较小。在大电流放电时,孔径在1.5nm^2nm的较大微孔对储存电能起主要作用。
Activated carbons （ACs） were prepared by simultaneous physical-chemical activation of coconut shells using ZnCl2 as activating agent. Their specific surface area and porosity parameters were calculated from the nitrogen adsorption-desorption isotherms at 77 K. The electrochemical properties of the electric double layer capacitors using these ACs as electrode materials were studied by a constant current charge-discharge technique and cyclic voltammetry. Results indicated that the specific capacitance of the carbon material could be as high as 360 F/g at a low discharge current of 5 mA, and it remained above 200 F/g at a larger discharge current of 50 mA. The influence of specific surface area and pore size on the electrochemical property was investigated. No special relationship was found between specific surface area and specific capacitance. However, the pore size had a significant influence on the specific capacitance. In a discharge at small current, the contribution of mesopore surface to the electric double-layer capacitance was larger than that of micropores. With increasing discharge current, the capacitance of mesopore surface decreased faster than that of micorpore surface. For discharge at a large current, supermicropores of 1.5-2 nm played an important role for the electrical energy storage.
出处
《新型炭材料》
SCIE
EI
CAS
CSCD
北大核心
2007年第4期355-360,共6页
New Carbon Materials
基金
国家自然基金(50472089)~~
关键词
同步物理-化学活化法
活性炭
双电层电容器
比电容
电极材料
Simultaneous physical-chemical activation
Activated carbon
Electric double-layer capacitors
Specific capacitance
Electrode materials
