Alkyl Imidazole Ionic Liquid Electrolyte Synthesis And Improvement Of Fuel Cell Performance

With many advantages such as zero vapor pressure, heat stability andcatalytic performance, ionic liquid is considered as the important branch ofgreen chemistry. Due to low Melting point, wide electrochemical window andgood electro conductivity, ionic liquid was also applied widely inelectrochemical field, including fuel cell, which assembled by anode, cathodeand electrolyte, and generate electronic energy directly from chemical energy. Ionic liquid is so employed as electrolyte of fuel cell to gain better batteryperformance in this thesis.1. Five kinds of imidazolium-based ionic liquids, such as [Bmim]Br,[Bmim]Cl,[Bmim]BF4,[Bmim]PF6and [Bmim]HSO4, were synthesized bysolvent-free microwave approach (SFMW) with yields of78.02%,77.49%,76.65%,78.07%and79.57%respectively. Compared with traditional solventheating method (TSH), the reation time of SFMW was only about1/200that ofTSH with keep the almost same yield. Only a small amountof organic solvent was used in the purification process and recycled, SFMWwas thence coincided with the concept of environmental protection.2. Orthogonal design is employed to investigate the effect of theexperimental parameters such as power of microwave, irradiation time andreactant ratio on the yield of [BMIm]HSO4. It was found that the highest yieldof80.57%reached at the optimized parameters of240W,20+10*15s and1:1.1ratio.3. The battery performance of five ionic liquid electrolytes wasinvestigated in home-made fuel cell. At H2as fuel, with the same currentdensity, the cell potential and the power density decreased following thesequence:[Bmim]BF4>[Bmim]PF6> NaOH>>[Bmim]Cl>[Bmim]Br>[Bmim]HSO4. on the contrary at methane as fuel, with the same current density,the cell potential and the power density decreased following the sequence:[Bmim]Br>[Bmim]HSO4>[Bmim]Cl> NaOH>[Bmim]BF4>[Bmim]PF6.4. The effect of temperature and water content on the performance of fuel cell with [BMIm]BF4electrolyte were also investigated. The results indicatedthat both of the cell potential and the power density decreased with increasing oftemperature or water content.In summary, SFMW almost without solvent coincided with the aim ofgreen chemistry, and the shorter reaction time would raise the ionic liquidsynthesis efficiency. Ionic liquids with the advantages of wide electrochemicalwindow, good conductivity and high stability, could be used as electrolyte toimprove the performance of fuel cell.