摘要
基于化学氧化聚合法制备了粒径约为40nm的掺杂对甲苯磺酸(TSA)的聚吡咯(PPy)复合纳米粒子.采用XRD、EDS、SEM和TEM研究了产物的结构和形貌特征,并用循环伏安、恒流充放电等方法测试了纳米粒子的电化学性能.结果表明PPy/TSA具有良好的快速充放电能力,在10 mA/cm2时比容量达到268Fg-1,但在1000次循环后发现其比容量下降了25.5%.用CV测试了PPy/TSA电极在第一次循环和第1000次循环的伏安曲线图,发现经过1000次循环后PPy/TSA电极的氧化峰逐渐消失,并且非法拉第电流减小.交流阻抗测试表明,PPy/TSA纳米粒子在反复充放电循环后,其界面电荷传递电阻增加,高频段双层电容值降低,但低频段的赝电容值却有所增加.通过比表面积测量发现,聚合物链的反复氧化-还原过程还可导致平均孔径减小、比表面积下降.红外和拉曼光谱也证实PPy纳米粒子在充放电过程中会发生降解,生成一种含氧的醌式结构,这表明聚合物电极材料比容量的下降可能与PPy主链的不可逆氧化和结构碎片化有关.
Polypyrrole nanoparticles were prepared by unstirred oxidation polymerization with TSA as dopant, the structure and morphologies of PPy/TSA nanoparticles were examined by X-Ray Powder Diffraction （XRD）, energy dispersive X-ray spectroscopy （EDS）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Results showed that the diameter of the sphere-like PPy/TSA nanoparticles was ca. 40 nm. The electrochemical performances of PPy/TSA were examined by the cyclic voltammetry （CV） , galvanostatic charge-discharge tests, the results indicated that PPy/TSA nanoparticles were characterized by promising reversible capacitance and had high rate-capability. Their specific capacitance was 270 F g^-1 at charging current of 10 mA cm 2. However, the specific capacitance decreased by ca. 25.5% after 1000 charging/discharging cycles. Electrochemical impedance spectroscopy （EIS） showed that the repeated charge/ discharge process could increase the charge transfer resistance, and reduce the high-frequency capacity of PPy/ TSA nanoparticles due to the decrease of pore diameter and specific area of the nanoparticles. In contrast,the capacity at low-frequency increased after 1000 cycles. Raman and infrared spectra proved that the deterioration of specific capacity of PPy/TSA nanoparticles was ascribed to the chemical degradation of the PPy/TSA owing to the repeated redox processes of PPy/TSA molecules.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2012年第4期410-417,共8页
Acta Polymerica Sinica
关键词
超级电容器
聚吡咯
氧化聚合
比表面积
容量衰减
Supercapacitor, Polypyrrole, Oxidation polymerization, Specific surface area, Capacity deterioration
