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 180.degree. 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 900.degree. C. to prepare ceramic powders in different particle sizes.

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