Thursday, January 28, 2010

Recipe for Nano-Scale Electrolyte for Solid Oxide Fuel Cell Detailed by Taiwanese Scientists

The recipe and preparation process of nano-scale electrolyte (YSZ/GDC/LSGM) suspension and its application via a spin coating process for fabrication of airtight/fully dense electrolyte layers composed in solid oxide fuel cell-membrane electrode assembly with high electrochemical performance, durability  and high degradation resistance. The attributes of the manufacturing process include low cost, high reliability and mass production capability. The nano-electrolyte recipe is described in U.S. Patent Application 20100018036.

According to inventors Yang-Chuang Chang (Taoyuan County, TW) Chun-Hsiu Wang, Tai-Nan Lin, Maw-Chwain Lee and Kao Wei-Xin, the recipe of nano-scale electrolyte suspension includes 10 to 50 wt % nano-scale electrolyte powder, 0.01 to 1 wt % poly acrylic acid (PAA as dispersant), 0.1 to 5 wt % poly vinyl alcohol (PVA as binder), 0.005 to 1 wt % octanol as defoamer, and deionized water as solvent. A solid oxide fuel cell fabricated via this recipe and process exhibits that the open-circuit voltage (OCV) is over 1 Volt, and maximum power density is 335 mW/cm2 at 800 degree. C.

The nano-scale ceramic powders are produced by a hydrothermal coprecipitation process. The process involves a reaction precursor of an aqueous solution of zirconium nitrate and yttrium nitrate ZrO(NO3)2, Y(NO3)3 in a controlled amount. The molar ratio for ZrO2 to Y2O3 is 0.92:0.08 in the finished product. The solution pH value is higher than 9.5 after a suitable amount of ammonium is added.

Then, white precipitates occur in the solution. The slurry is put in an autoclave at a temperature of C  and a pressure of 140 psi for a reaction time of 8-24 hours. When the reaction is completed, the powders are collected and rinsed with deionized water for several times. After drying, nano-scale YSZ ceramic powders are obtained. Depending on needs, the YSZ ceramic powders are subject to calcination at 600 to about C. to prepare ceramic powders in different particle sizes.

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