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Mechanical Properties of Cesium Hydrogen Sulfate for Fuel Cell Applications

CSEF · 2007 Applied Mechanics & Structures Second Award

Christopher K. Lee · Walnut High School, Walnut, Los Angeles County

Overview

Objectives/Goals Cesium hydrogen sulfate (CHS) is a solid acid that has been demonstrated as a promising fuel cell electrolyte; however, its poor mechanical strength may undermine fuel cell stability. The mechanical properties of CHS were investigated to characterize plastic deformation, and thus to guide the development of improved composites. Methods/Materials Creep deformation was studied under 0.3 MPa-1.0 MPa stress at a temperature range of 120-160 ºC. Three data verification procedures were taken to strengthen results. A homemade ball mill and a thermomechanical analyzer were utilized. Results At temperatures above the superprotonic phase transition (SPT), creep activation energy is 200±10 kJ/mol and appears to be limited by cesium ion diffusion. Stress exponents at different temperatures were determined and changed from n ~ 1 to n ~ 2 upon SPT, confirming that the deformation has dependency on SPT. Unique behaviors were also characterized. Conclusions/Discussion A complete understanding of these properties resulted in the engineering and identification of a silica nanocomposite material with superior mechanical properties.

Summary statement

Logical scientific methodology was utilized to engineer a material with superior mechanical properties.

Help received

Used lab equipment at the California Institute of Technology under the tutelage of Mikhail Kistlitsyn

Awards (1)

Competition history

  • CSEF 2007 Applied Mechanics & Structures · Entry S0216

Resources

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Source: California Science & Engineering Fair public projects

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