A poly(dimethylamine-co-epichlorohydrin-co-ethylenediamine) bisulfate ionic liq. and 2 its modifications with dihydroborate and dihydrophosphate anions were added to the Pb-acid battery electrolyte to study their effect on H-2 and O-2 evolution potentials and corrosion current and potential. The ionic liq. with bisulfate and dihydroborate anions significantly reduced corrosion current and increased the corrosion potential after 5 h. A passive layer was formed on the working electrode and stopped the corrosion.