Synthesis of deep eutectic solvents of N, N, N-trimethyl butylsulphonate ammonium hydrosulfate-urea and their performance investigation as electrolytes in fuel cells

The preparation and characterization of three deep eutectic solvents (DESs) using N, N, N-trimethyl butylsulphonate ammonium hydrosulfate (DES1-0) as hydrogen bond acceptor (HBA) and urea as hydrogen bond donor (HBD) are presented. DES1-0 and three DESs are used as electrolytes to test the performance for fuel cell. The results show that the designed DESs have high performance. The maximum power density (MPD) with the four samples follows the order at 30 degrees C and 50 degrees C: DES2-1 > DES1-0 > DES1-1 > DES1-2. DES with DES1-0 to urea in 2:1 ratio (DES2-1) shows the highest performance, and the MPD of 80.20 mW center dot cm(-2) has been achieved at 50 degrees C. DES2-1 increases the proton diffusion coefficient and speeds up proton transfer rates, so it can provide higher performance than single DES1-0 ionic liquid. In addition, the equivalent circuit model shows that the electrode process of the four samples is in the control of both charge transfer and diffusion processes. Only DES which have high capacitance and low resistance can achieve high performance for fuel cell. DES2-1 has the largest electric double layer capacitance at electrode/electrolyte interface (C-d) and the smallest Warburg impedance resistance (W-0) among all electrolytes in this paper, and it has the low solution resistance (R-u) and charge transfer resistance (R-ct); therefore, its performance in fuel cell is the highest.

Automated summary

The preparation and characterization of three deep eutectic solvents (DESs) using N, N, N-trimethyl butylsulphonate ammonium hydrosulfate (DES1-0) as HBA and urea as HBD are presented. The DESs are used as electrolytes for fuel cells, and show high performance, with DES2-1 exhibiting the highest performance.