Studies On Hydrogen Evolution Inhibition And Its Mechanisms Of Negative For Lead-carbon Batteries

Lead-acid battery is considered as a promise for hybrid electric vehicles(HEVs) and energy storage applications because of low cost, mature technology and high recycling efficiency. However, it suffers from shorter than desired cycle life at high discharge rate or under high-rate partial-state-of-charge(HRPSoC) conditions due to the formation of irreversible hard sulfate in negative plates. Integration of higher than usual content carbon into negative electrode has been identified as an effective way to solve this problem. Nevertheless, the carbon material can easily cause severe hydrogen evolution, increase the inner pressure and accelerate water loss and negatively influence the battery performance. Therefore, the hydrogen gassing would be the most challenging issue for developing lead-carbon battery.In this work, the mechanism of hydrogen evolution on carbon material under battery operating condition has been studied. And the influence of structure modification of various carbon materials and the addition of hydrogen evolution inhibitors have also been investigated, in order to develop effective ways to suppress HER and prolong the cycling life of lead acid battery. The main contents are summarized as follows:1. Seven different activated carbon materials with various surface area and pore size were prepared by ZnCl2-CO2 physical and chemical activation method. And the influence of specific area and pore diameter distribution on the hydrogen gassing rate was investigated by electrochemical methods. The results indicate: The hydrogen gassing rate increases with higher mesoporous volume. Therefore, in order to guarantee that carbon materials have the high specific surface and high overpotential of hydrogen evolution reaction, the proportion of microporous and mesoporous need to be properly controlled.2. The influence of heteroatom doping, including P, B, N and F, on the hydrogen evolution reaction was investigated and the underlying mechanism was analyzed. The results indicate: hydrogen evolution reaction on activated carbon was significantly hindered with P, F and N doping, while no obvious influence was examined by B doping. This phenomenon can be attributed to the charge redistribution induced by the difference of electronegativity between heteroatom and carbon, which is further verified by theoretical calculations.3. The hydrogen evolution inhibition effect of bismuth oxide and gallium oxide as hydrogen evolution inhibitors in lead carbon batteries was investigated. The results show that the hydrogen evolution reaction has been effectively inhibited when hydrogen evolution inhibitors were added in carbon materials. The cycle life of batteries under HRPSoC improved significantly. Furthermore, the optimized mass ratio of bismuth oxide and gallium oxide was 2.5:5.5.