Aluminum Electrolytic Capacitor With The Synthesis And Applications Of Novel Electrolytes

Branched long-chain carboxylate have been applied in working electrolyte for aluminum electrolytic capacitors because they have superiority thermal stability, high solubility in EG solution, favorable chemical self-recovering ability, and so on. In this paper, the new-type electrolyte——side-chain polycarbon dibasic acid (SCPDA) was developed and the synthesis craft of SCPDA was systematic researched. The properties and structure of SCPDA were tested and characterized, and then the electrochemical properties of SCPDA in EG solution and the application of SCPDA in aluminum electrolytic capacitor were studied. The main contents are as follows.In this paper, SCPDA was synthesized by ester synthesis, hydrolysis, acidification first using cyclohexanone and isoprene as raw material. The factors such as material ratio, reaction temperature, reaction time by way of orthogonal and single factor experiment were systematic studied on the synthesis of SCPDA. The results have shown that the yield of SCPDA could reach 61.3% at the best condition when cyclohexanone and isoprene reacted with same mole, synthesis temperature was -10～-5℃, synthesis time was 2 h, hydrolysis temperature was 95℃, hydrolysis time was 3h.The physical and chemical properties and structure of SCPDA were tested and analyzed using KF-ⅡMicro moisture apparatus, acid-base titration, FT-IR and TG.. The results have shown that the synthesized SCPDA was long-chain carboxylic acid substance, its water content was 0.37%, and acid value was 298.1mg KOH/g. It had good thermal stability, and its main loss temperature was 220～340℃,so SCPDA was applicable to the aluminum electrolytic capacitor which the working temperature was at 125℃.Putting the synthesized SCPDA into EG solution, the influence of ammonolysis pH value and concentration of SCPDA on the sparking voltage, conductivity were investigated, and contrast with ammonium sebacate in EG solution. The results have shown that the best ammonolysis pH value of SCPDA was 7.4～8.2, the sparking voltage decreased with increasing concentration of working electrolyte, but the conductivity was the opposite. The ammonium of SCPDA in EG solubility was much higher than ammonium sebacate, when the electrolyte concentration was at 5%, the sparking voltage of SCPDA electrolyte was higher 38V than the ammonium sebacate electrolyte, but conductivity was lower 0.203 ms/cm.The ammonium of SCPDA,PA-08,M-18 as main electrolyte were separately further prepared into working electrolyte of aluminum electrolytic capacitors, and the capacitors performance of capacitance variation, loss tangent, leakage current, life have been studied. The results have indicated that the sparking voltage of working electrolyte including the ammonium of SCPDA was higher 20V than the others but the electric conductivity was slightly lower, and corresponding capacitors had lower capacitance variation, loss tangent, leakage current and better high-temperature stability. After 1440 hours, 135℃high temperature accelerated test, each parameter of the capacitors which were made of ammonium of SCPDA passed capacitor tests'standard, and the life would pass 10000 hours at 105℃when work normally.