Influence of Electropolymerization Conditions on the Capacitance and Dissipation Factor of Polypyrrole Tantalum Electrolytic Capacitors
Xu Youlong,Ji Rui,Wang Fei
(Key Laboratory for Phsical Electronics and Devices of the Ministry of Education，Xi'an Jiaotong University,Xi'an 710049,China)

Abstract: The approaches,by which conducting polypyrrole could be electrodeposited on the surface of tantalun/tantalum pentoxide-based anode(1 microfarad, 16V), have been studied. The galvanostatically polymerized polypyrrole is used for the cathodes of tantalum electrolytic capacitors. Particularly, the influence of electropolymerization conditions, suchassupporting electrolyte solution composition, anodic current value and appliedmode, on the capacitance and dissipation factor of as-made capacitor has been dis cussed. With over concentration of pyrrole and electrolyte, there was a disadvantageous effect on the properties of as-made samples. However, it is benefit to keep the ratio of concentration of pyrrole and electrolyte between 3～4.The properties would be deteriorated with the increase of anodic currect, so the anodic current should be below 1.2 mA. Samples with capacitance almost 98 percent of the rated capacitance and low dissipation factor less than 0.013 were accomplished in supporting electrolyte using mixture of acetonitrile and 1,2-propanediol carbonate as solvent. During the electropoly merization process, a larger anodic current first, a smaller one later, must be applied.
Keywords: tantalum electrolytic capacitors; conducting polypyrrole; galvanostatically electropoly merized; supporting electrolyte solution; anodic current