Energy harvesting from CO₂ emission exploiting an ionic-liquid based electrochemical capacitor

The global warming is one of the most serious problems that the humanity facing in his history and the main cause is the high presence of CO₂ in the air due anthropogenic activities. This thesis work analyzes the CO₂ capture mechanism performed by imidazolium-based ionic liquid and it describes an electrochemical device which is able to convert the potential chemical energy released during the capture phase into electrical power. The approach used is innovative because it is not based on pH variations, redox reactions or EDL size alteration. The electrochemical cell, which is the basis of this method, is composed by two gas diffusion layers (d=16mm) and a polymeric separator impregnated with 100μl of an ionic liquid that acts and as capture media and as electrolyte. The work demonstrates that the device is able to produce electrical power when carbon dioxide flux and nitrogen flux alternately reach the electrolyte and react with imidazole molecules forming imidazole carbamate. In practice, the energy released during the carbamate formation is exploited to generate a potential difference between two electrodes. In order to improve the extractable power, several materials have been analyzed and the results show as the best performance are provided from an electrochemical cell composed by two electrodes obtained by deposing an activated carbon based mixture on a gdl and using a solution of [DBUH][Im] 1M in propylene carbonate as electrolyte. The average power density is 77μW/m².