Investigation of Capacitance and Resistance Distributions Inside Electrolytic/Electrochemical Hybrid Capacitors

摘要

AC and dc performance and leakage current of hybrid capacitors consisting of porous tantalum oxide anode electrode and ruthenium oxide cathode electrode were examined and characterized. It was found that the capacitance was insensitive to current density up to 110 mA/cm~2, and temperature ranging from -70 to 50℃. The RC time constants were in the range from 2 to 0.45 ms and dependent on the maximum operational voltage of the capacitor. The gravimetric and volumetric energy densities of hybrid capacitors were in the range of 0.074 to 0.233 J/g and 0.388 to 1.384 J/cm~3, respectively. The gravimetric and volumetric power densities of hybrid capacitors were in the range of 19 to 259 W/g and 100 to 1540 W/cm~3, respectively. A comparison of the performance between hybrid capacitors to conventional aluminum and tantalum electrolytic capacitors was made in this study. During dc charge and discharge cycles, the potential of the cathode electrode was within the electrochemical stability window. However, a sudden voltage-jump as high as 7.5 V could occur at the cathode electrode during a short circuit discharge. The resistance distribution inside the capacitor was also determined to be 47%, 28%, and 25% from the cathode, anode, and electrolyte, respectively.