Super Dielectric Materials

Abstract

Evidence is provided here that a class of materials with dielectric constants greater than 105 at low frequency (<10−2 Hz), herein called super dielectric materials (SDM), can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants, near 0 Hz, greater than 4 × 108 in all cases, a remarkable increase over the best dielectric constants previously measured for energy storage capabilities, ca. 1 × 104. It is postulated that any porous, electrically insulating material (e.g., high surface area powders of silica, titania, etc.), filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution), herein called New Paradigm Super (NPS) capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relatively high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å) of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 V, water begins to break down, creating enough ionic species to “short” the individual water droplets. Potentially NPS capacitor stacks can surpass “supercapacitors” in volumetric energy density.

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

“…The theory suggests that capacitors with graphene electrodes could have an ultimate energy density of ~800 J/cm 3 , a value far less than the current generation commercial lithium ion battery (~2200 J/cm Recently, a new type of 'supercapacitor' was invented, NP supercapacitors (NPS) with energy density rivaling the best prototype EDLC, but based on an entirely different paradigm [8][9][10][11][12][13][14]. Unlike EDLC that gain energy density through the use of high surface area electrodes with low dielectric value, NPS use low surface area electrodes and dielectrics with remarkably high dielectric constants, specifically super dielectric materials (SDM), that is materials with dielectric values greater than 10…”

“…SDM are composed of an 'active phase', such as salt dissolved in a liquid, and an 'inactive' mechanical phase such as anodized titania, T-SDM [8,9], high surface area porous refractory oxides, Powder-SDM [10][11][12], or even simple fabrics, Fabric-SDM [13], that hold the active phase in place. The theoretical basis of SDM [8,9] is that in an electric field the ions in solution travel to create dipoles, which are far longer (ca.…”

Testing the Tube Super-Dielectric Material Hypothesis: Increased Energy Density Using NaCl

“…The SDM hypothesis is that any porous dielectric material filled with a liquid phase containing ions in solution will have very high dielectric values, at least at low frequency, by virtue of the separation of ions/dipole formation in the liquid phase induced by an applied field. 1,2 The dipoles thus created in the dielectric will oppose the applied field, decreasing the net voltage, at any charge density on the electrodes, and concomitantly increasing the capacitance. In essence, the SDM hypothesis is an extension of the classical model of polarizable (or ponderable) materials.…”

“…For example, several alumina powders mixed and filled with salt (NaCl) water were found to have dielectric constants as much as seven orders of magnitude higher than that of the best dielectric, barium titanate. 1,2,4 More recently, a second type of SDM, tube SDM (T-SDM), was built and tested. 3 These were transition metal oxide nanotube arrays, created by anodization of a metal foil substrate, and filled with aqueous salt solutions.…”

“…[1][2][3][4] These dielectric materials are made up of porous, electrically insulating solids in which the pores are filled with liquids containing ionic species (e.g., water with dissolved salt). The SDM hypothesis is that any porous dielectric material filled with a liquid phase containing ions in solution will have very high dielectric values, at least at low frequency, by virtue of the separation of ions/dipole formation in the liquid phase induced by an applied field.…”