Performance of Aqueous Ion Solution/Tube-Super Dielectric Material-Based Capacitors as a Function of Discharge Time

Abstract

The discharge time dependence of key parameters of electrostatic capacitors employing a dielectric composed of the oxide film formed on titanium via anodization, saturated with various aqueous ion solutions, that is tube-super dielectric materials (T-SDM), was thoroughly documented for the first time. The capacitance, dielectric constant, and energy density of novel paradigm supercapacitors (NPS) based on T-SDM saturated with various concentrations of NaNO 3 , NH 4 Cl, or KOH were all found to roll-off with decreasing discharge time in a fashion well described by simple power law relations. In contrast, power density, also well described by a simple power law, was found to increase with decreasing discharge time, in fact nearly reaching 100 W/cm 3 for both 30 wt% KOH and NaNO 3 solution-based capacitors at 0.01 s, excellent performance for pulsed power. For all capacitors, the dielectric constant was tested, which was greater than 10 5 for discharge times >0.01 s, confirming the materials are in fact T-SDM. The energy density for most of the capacitors was greater than 80 J/cm 3 of dielectric at a discharge time of 100 s, once again demonstrating that these capacitors are competitive for energy storage not only with existing commercial supercapacitors but also with the best prototype carbon-based supercapacitors.

Toward an Improved Understanding of the Role of Dielectrics in Capacitors

“…The primary role of the separator in EDLC is to prevent shorting. Notably, there is no separator in any of the previous SDM studies [ 1 , 2 , 3 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], and no shorts were ever detected.…”

“…A simple test of the postulate was conducted. A form of super dielectric material (SDM), a recently invented class of materials [ 1 , 2 , 3 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], was placed on the outside of several parallel plate capacitors. In all cases the core structure, classically considered “the capacitor”, consisted of two titanium metal electrodes with a thin sheet of low dielectric constant (<200) material between.…”

“…A second objective of this study was to demonstrate that SDM can be observed with metal electrodes as well as the carbon electrodes employed in all previous studies [ 1 , 2 , 3 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Titanium was selected as the electrode material, as more traditional electrode materials, such as copper and aluminum were found to corrode rapidly due to the aggressive chemistry generated by SDM at elevated voltage.…”

Super Dielectric Material Based Capacitors: Punched Membrane/Gel

“…Also, in Fig. 8 are the results, described in more detail elsewhere [22][23][24][25] for NPSupercapacitors based on aqueous KOH solutions filling vertical tubes in the oxide layer of anodized titania (T-SDM). An extrapolation of the performance of those capacitors appears to surpass that of even lithium ion batteries.…”

Understanding Dielectrics: Impact of External Salt Water Bath

“…This was tested and found accurate in earlier work [3,4]. Other work showed that, as predicted by the model, high dielectric constants would be found for salt water saturated fabric [5], for salt water saturated nano-tubes on the surface of anodized titania [6], for porous solids saturated with various salts [7,8], for fumed silica gels containing salt water [9], for water saturated with salts other than NaCl such as KOH and NH 3 Cl [10]. Other studies show that both metal and carbon can be used as the electrode material [2], and for non-aqueous polar fluids such as DMSO containing dissolved salts, etc.…”