乙炔黑电极材料的双电层电容器制备与性能研究

利用乙炔黑为导电粉体,以PrFE为胶粘剂成功制备了具有较好充放电性能的多孔结构双电层电容器.利用TEM测定了电极材料乙炔黑的粉末形貌,利用SEM测定了电极的表面形貌,利用充放电电路测定了电容器的充放电曲线.研究结果表明,电极加工压力减小,小半径的孔洞所占比例下降,电极的实际使用表面积增大,比容量增高.压力从48Mpa下降到16MPa,比容量增大17%.压力大于48MPa,压力对电极的有效面积影响不大.胶粘剂含量下降,有效使用面积增大,电容器比容量提高.胶粘剂从14%降低到6%,比容量增大46%.压力增大导致电极的有效面积降低,电极上电荷密度提高,充电后的保持电压增大.电解液浓度增大,通过影响极板电荷密度,充电保持电压也有所提高.多孔电极的孔径分布,尤其是小孔径孔洞含量的增加直接影响了双电层电容器的充放电过程.随制备压力增大,小孔量增加,初期放电缓慢,后期加速.

Fabrication and Properties of Double-layer Capacitor with Acetylene Black Electrode

Porous electric double-layer capacitors were prepared successfully with acetylene black and PTFE, where acetylene black was used as electrode precursor and PTFE as a binding. The acetylene powder and the electrode microstructure were measured by both TEM and SEM respectively. The charge-and-discharge curves were measured using a charge/discharge meter. In conclusion, the specific capacitance of the double-layer capacitors increased with the decrease in preparation pressure of the electrode due to increasing both the proportion of the effective micro-pores and the available surface. As the preparation pressure decreased from 48MPa to 16MPa, 17% of the specific capacitance was increased. However, when the pressure was above 48MPa, the capacitance had almost no change with decreasing preparation pressure because the pressure affected hardly on available surface. Moreover, the specific capacitance increased with decreasing PTFE binding due to the increase in available surface. 46% of the specific capacitance was actively ascended as PTFE decreased from 14% to 6%. In addition, the charge density increased, hence the chargeable voltage increased with the increase in available surface because of high preparation pressure. Likewise, the charge density might increase and the chargeable voltage then increased with the increase in concentration of the electrolyte. Both the charge and the discharge behaviors of the double-layer capacitor were directly related to both the distribution and size of electrode pores. The capacitor discharge slowly first and then speedily while the proportion of the micro-pores increased with increasing preparation pressure.