Performances of Aluminum Electrolytic Capacitors Using Silica Organo-Sols as Electrolyte Additives

100V aluminum electrolytic capacitors with high performance are strongly demanded from the market. Silica or aluminosilicate ethylene glycol sols in combination with three kinds of organo-phosphorous acids were added into a quaternary alkylammonium salt-based electrolyte solution to increase its sustaining voltage while keeping its high electrolytic conductivity and high thermal stability. In addition to the ordinary life evaluation test, investigation of initial electric properties and assessment for sustaining voltage of capacitors using those electrolyte solutions during dc-load life tests at 378 K were performed. Consequently, we observed that the combination between aluminosilicate ethylene glycol sol and dibutyl phosphate gives the most promising performance. The capacitors using the optimized electrolyte afforded less than one-half ESR at 233 K and more than twice the durability compared with those using a conventional electrolyte solution. These results demonstrate the possibility to apply quaternary ammonium salt-based electrolyte solutions for 100 V aluminum electrolytic capacitors.