The Effect Of Hydrogen Evolution Inhibitors On The Electrochemical Performance Of Pb-C Negative Plate

Pb-C batteries are encouraged to become a power source of hybrid electric vehicles due to their excellent cyclic stability on a high rate partial-state-of-charge (HRSOC). Addition of some carbon or graphite forms to the negative paste mix improves the cyclic stability, which make Pb-C batteries different from other lead-acid batteries. However, carbon additives accelerate hydrogen evolution of the negative plates. To hinder hydrogen evolution, we research hydrogen evolution inhibitors and the mechanism of indium oxide on eliminating hydrogen evolution that take place at the negative plates of lead-acid batteries,which are based on optimization studies of EAC carbon additives.At the beginning, we research the effect of the additives on the rate of hydrogen evolution. The different rate of additives such as In₂O₃, Ga₂O₃ and Bi₂O₃ are added to negative paste mix through mechanical mixing. And the samples of plates prepared are characterized by linear and voltammetry scanning test. The results show all of hydrogen evolution inhibitors can eliminate hydrogen evolution, as well as optimal rate of In₂O₃, Ga₂O₃ and Bi₂O₃ are 4%,2%,8%, respectively. Cyclic voltammetry and linear voltammetry scanning test show a part of In₂O₃ transform to In₂(SO₄)₃ on charge and discharge processes of negative plates of lead-acid batteries.In this paper, we research effect of different rate of hydrogen evolution inhibitors on the electrochemical performance of Pb-C negative plates with 0.5%EAC. Cyclic number of Pb-C negative plate with 0.5% EAC and without hydrogen evolution inhibitors was 2546. Following the addition rate of In₂O₃, Ga₂O₃ and Bi₂O₃ increasing, the cyclic life of Pb-C negative plates with hydrogen evolution inhibitors shows gaussian distribution. The optimal rate of In₂O₃ in Pb-C negative plate was 0.01% with cyclic number of 12966, which was six time than plate without inhibitors; the optimal rate of Ga₂O₃ in Pb-C negative plate was 0.01%, whose cyclic number was 5966; the optimal rate of Bi₂O₃ in Pb-C negative plate was 0.02% with cyclic number of 6864, whose optimal rate was higher than other inhibitors. The result show 0.04% In₂O₃, 0.005% Ga₂O₃, 0.04% Ga₂O₃and 0.04% Bi₂O₃ reduced cyclic life of negative plate, which indicate the addition rate of inhibitors is key factor for cyclic stability of negative plate.We also investigate mechanism of indium oxide on eliminating hydrogen evolution that take place at the negative plates of lead-acid batteries. The negative plate with indium oxide is characterized through SEM, XRD and EDS, whose result combined with EIS, CV and ICP show little of In₂O₃ can dissolve in electrolyte and a lot of In₂O₃ and In₂(SO₄)₃ exist in negative paste mix. The excess In₂O₃ make active material aggregated, specific surface area reduced, electrical conductivity decrease and crystallinity worse, which reduced the cyclic life of negative plate.