Thermally Stabilized Polyaniline With m-Xylylenedisulfonic Acid And Its Application For A Counter Electrode Of A Tantalum Capacitor

Abstract

ABSTRACTWe have succeeded in preparing a conductive polyaniline (PAn) with improved thermal stability from a chemical oxidative polymerization of aniline by using an oxidant and a novel protonic acid, m-xylylenedisulfonic acid (XDSA). The acid was synthesized from dibromoxylene and characterized by elemental analysis, IR and NMR spectroscopies. The polymer which is doped with XDSA shows a high conductivity of 5 S/cm. The conductivity does not change with annealing at 125°C in air for over 1000 hours. This polymer exhibits good thermal stability, and this stability is attributed to XDSA dopant, which consists of a bi-functional sulfonic group bonded to a polymer chain. By immersing an anodized tantalum pellet into a reactive solution, PAn doped with XDSA film is formed on the dielectric surface. The tantalum capacitor using PAn doped with XDSA as a counter electrode shows the improved characteristics: high apparent capacitance (90%), and small series resistance (<200mΩ at 100kHz). The capacitor demonstrates an excellent thermal stability due to because of the exceptional heat-resistance of PAn doped with XDSA formed in the capacitor.