Results of theoretical and experimental studies of corrosion processes of graphite in vanadium electrolytes and methods for corrosion prevention are presented. Electric contact of positive half-cell electrolyte in the inlet/outlet channels of vanadium redox flow batteries (VRFB) with graphite collectors generates parasitic electric currents, which cause electrochemical oxidation of carbon atoms on the surface of the collectors. This leads to damaging the collectors and flow battery failure. The parasitic currents in the electrolyte channels were calculated and measured. Methods to prevent the corrosion, caused by the parasitic currents, were investigated: the graphite planar collectors were electrically isolated from electrolyte in inlet/outlet channels by o-rings and in inlet/outlet area of half-cell by isolation films. A corrosion resistant battery with collectors, fabricated from pyrolytic graphite, was constructed.