(593i) High Density Oxygen Storage in Nanometer Scale Deep Capillaries

We present a general gas storage system using nanocapillary arrays instead of a conventional tank. Aluminum anodization produces a regular array of deep, ultra-high aspect ratio nanocapillary arrays. Covering and sealing the nanocapillaries with a membrane electrode sealing assembly (MESA), gas can be electrochemically pumped into and out of these capillaries, creating a safe way to store gas at immense pressure tolerance, then electrochemically regulating release. In this approach, a partial rupture will vent only the gas in the affected arrays rather than effecting a total containment failure. The nanocapillary approach is also theoretically capable of 2-3 times the gravimetric and volumetric storage capacity of compressed gas cylinder. This presumes resolving several problems with the multiple step manufacturing process.

Many parameters contribute to storage capacity, primarily nanocapillary depth and MESA performance. Applied voltage and temperature during anodization encourage growth of the nanocapillary array, boring deeper over longer periods. Current progress shows capillary depths of approximately 3.1 mm at an average diameter of 100 nm. Cyclical polarization results demonstrate membrane effectiveness in electrochemical pumping and the required reversible dissociation of input species into ionic form. These measurements highlight the need for catalyst both inside of each nanocapillary and outside of the MESA for facile and reversible pumping. Various combinations of catalysts demonstrate improvements to pumping performance, leading to usable amounts of gas and a repeatable storage versus release capability for up to 10 cycles. This talk will cover the required advances in many storage device manufacturing steps as well as the characteristics of electrochemical compression in nanoscale ionomer materials. The status of the overall storage device efficacy will be discussed.

[DISTRIBUTION STATEMENT A. Approved for public release; Distribution is unlimited 412TW-PA-19122]