Novel ionic liquid electrolyte for electrochemical double layer capacitors

A novel oxygen containing spiro ammonium salt, oxazolidine-3-spiro-1’-pyrrolidinium tetrafluoroborate (OPBF4) was synthesized using an innovative technique for use as electrolyte in electrochemical double layer capacitors (EDLC). Comparison of OPBF4 with commercially available, tetraethyl ammonium tetrafluoroborate (TEABF4) showed higher voltage window and higher capacitance for the OPBF4 compound. Moreover, molarity of 3 M was produced with OPBF4 as compared to a maximum of 1.5 M for TEABF4 in acetonitrile (AN). This is especially important to enable the fabrication of higher energy density EDLC. This is the first report of testing OPBF4 compound in an EDLC device, and it qualifies as a reasonable alternative to TEABF4 for high performance ultracapacitors.