Performance enhancement of phosphoric acid fuel cell using phosphosilicate gel based electrolyte

Replacement of phosphoric acid electrolyte by phosphosilicate gel based electrolytes is proposed for performance enhancement of phosphoric acid fuel cell (PAFC). Phosphosilicate gel in paste form and in powder form is synthesized from tetraethoxysilane and orthophosphoric acid using sol-gel method for two different P/Si ratio of 5 and 1.5 respectively. Replacement of phosphoric acid electrolyte by phosphosilicate gel paste enhances the peak power generation of the fuel cell by 133% at 120 ℃ cell temperature; increases the voltage generation in the ohmic regime and extends the maximum possible load current. Polyinyl alcohol (PVA) is used to bind the phosphosilicate gel powder and to form the hybrid crosslinked gel polymer electrolyte membrane. Soaking the membrane with phosphoric acid solution, instead of that with water improves the proton conductivity of the membrane, enhances the voltage and power generation by the fuel cell and extends the maximum possible operating temperature. At lower operating temperature of 70 ℃, peak power produced by phosphosilicate gel polymer electrolyte membrane fuel cell (PGMFC) is increased by 40% compared to that generated by phosphoric acid fuel cell (PAFC). However, the performance of composite membrane diminishes as the cell temperature increases. Thus phosphosilicate gel in paste form is found to be a good alternative of phosphoric acid electrolyte at medium operating temperature range while phosphosilicate gel-PVA composite offers performance enhancement at low operating temperatures.