Additives of Suppressing Hydrogen Evolution at Carbon- Containing Negative Plates of Valve-Regulated Lead-Acid Batteries

摘要

The effects of several rare earth oxides and fluorine-containing compounds as additives on thehydrogen evolution at the negative plates containing commercial and purified carbon materials invalve-regulated lead-acid (VRLA) batteries have been studied by means of the constant currentpolarization and hydrogen gassing measurements. The activated carbon (AC) and iron impurity in thecarbon materials greatly accelerate the hydrogen evolution. La2O3, Sm2O3, Gd2O3, Nd2O3, Dy2O3 andpolytetrafluoroethlene (PTFE) as electrolyte additives inhibit the hydrogen evolution. When thehydrogen evolution polarization potential is small as in the case of the oxygen depolarization in theoxygen cycles, the addition of 0.025% PTFE and 0.025% Dy2O3 additives to electrolyte increase itsoverpotential, but these two additives can promote the hydrogen evolution at negative platescontaining activated carbon (AC), expanded graphite (EG) or flake graphite (FG) with low impuritycontents. In the test of cycle life of the 12 V 12 Ah VRLA batteries with the negative plate containingacetylene black (AB), the combined additive of PTFE and Dy2O3 greatly increases the chargeefficiency and thus decreases water loss.