Study Of Metal Compounds As Hydrogen Evolution Inhibitors For Lead Carbon Battery Anodes

Lead-acid batteries are attracting much attention in hybrid electric vehicles?HEVs?and energy storage applications because of low cost,long history and mature technology.However,traditional valve-regulated lead-acid?VRLA?battery suffers from shorter cycle life?300-500 cycles?,especially at the high discharge rate or under high-rate partial-state-of-charge?HRPSoC?duty,due to the formation of irreversible hard sulfate in negative plates,which cannot meet the market demand.To solve the problem,integrating appropriate content of carbon into the negative-active-mass?NAM?of VRLA battery,has been demonstrated to be an effective way to alleviate the irreversible accumulation of lead sulfate on the negative plates.Compared with the Lead acid battery,Lead-carbon battery has higher power density and longer cycle life.However,high content carbon additives can cause side reactions of hydrogen evolution reaction?HER?at the end of charge process in the negative plates due to its low overpotential of hydrogen evolution,accelerating water loss and battery failure,which poses an urgent issue to be overcome.There are two ways to address the problem.On the one hand,modifying carbon materials is an effective way to improve the overpotential of hydrogen evolution,such as the regulation of specific surface area and porosity and doping N,P impurity atoms.On the other hand,adding the hydrogen evolution inhibitors into the negative materials or electrolyte of the battery.In this thesis,the hydrogen evolution inhibitors and activated carbon composites were synthesized and studied as a negative additive for lead-acid battery.The main results are summarized as follows:1.Bi₂O₂CO₃/AC composites have been synthesized via a hydrothermal method,and Bi₂O₂CO₃ was investigated as a promising hydrogen evolution inhibitor for lead-acid battery.The electrodes with Bi₂O₂CO₃/AC composites have lower hydrogen evolution current and more negative hydrogen evolution potential,of which 4 wt%Bi₂O₂CO₃ is an optimized content.4%Bi₂O₂CO₃/AC electrode shows the most negative HER onset potential value of-1.05 V,about 230 mV more negative than that of pristine AC electrode.The hydrogen evolution currents of Bi₂O₂CO₃/AC composite electrode at the same potential?-1.35 V vs.Hg/Hg₂SO₄?is much smaller than that of AC,reducing by 93.1%.Adding Bi₂O₂CO₃/AC composites into the negative materials of the Lead-acid cell has remarkably increases the cycle life.With an optimized content of 4%Bi₂O₂CO₃/AC additive,Lead-carbon module cells yield a lifespan up to 19637 cycles,which is over three fold of the lead acid cell.Moreover,owing to the uniform distribution and strong interaction between AC and Bi₂O₂CO₃,Bi₂O₂CO₃/AC composites exhibit much better performance as a negative additive than that of Bi₂O₃/AC composites.So Bi₂O₂CO₃/AC composites additives show a promising application prospect.2.ZnSO₄ have been investigated as a promising hydrogen evolution inhibitor for lead carbon battery.Compared with AC electrode,ZnSO₄/AC composites electrodes show lower hydrogen evolution current and more negative hydrogen evolution potential.The electrode with 4%ZnSO₄/AC composite has the smallest hydrogen evolution current under the-1.35V?vs.Hg/Hg₂SO₄?potential,only 52.5%of the original activated carbon electrode,and the hydrogen evolution potential of the 4%ZnSO₄/AC composite electrode also negatively shifted by 110 mV.Compared with lead-acid cell,the lead-carbon cell with ZnSO₄/AC composites addition has longer cycle life.The lead-carbon cell with 4%ZnSO₄/AC composites addition shows the best cycle performance,which is over two fold of the lead acid cell.3.Activated carbon with a specific surface area of 1859.6 m² g^-11 was prepared by KOH activator,on the basis of which,ZnO/AC composites were prepared by the decomposition of Zn?CH₃COO?₂ activator and the hydrogen evolution inhibition effect of ZnO composites was investigated.The results show that ZnO/AC composites have higher specific surface area and the electrodes with ZnO/AC composites show lower hydrogen evolution current than primary activated carbon.4 wt%ZnO is an optimized content.In this work,ZnO/AC composites were formed by the decomposition of Zn?CH₃COO?₂ activator in the process of activated carbon formation,and the process was simple,which was expected to achieve large-scale applications in the field of lead-carbon battery...