Research On Design And Application Of Positive Alloys With Strong Corosion-resisitant For Long-life Lead-carbon Battery

As one of the most widely used secondary batteries,lead-acid batteries has a history of more than 160 years,but the short life span limits its large-scale applications in the field of energy storage.The appearance of lead-carbon battery technology in 2004provides new opportunities for the technological development and market application of lead-acid batteries.Currently,advanced lead-carbon batteries have reached a cycle life of more than 4,000 times?60%DOD,Depth of Discharge?,and have been gradually applied in the field of electric energy storage.The corrosion of the positive grid has become a key factor limiting the cycle life.It is of great importance for theoretical research and market development to extend the corrosion life of the positive grid,and thus obtaining an ultra-long-life lead-carbon battery?cycle life?6000 times?.In this paper,the corrosion behaviors of the positive grid alloy are studied from three aspects:the influence of alloy composition,the growth of the interface corrosion layer,and the corrosive environment.The composition of the positive grid alloy and the preparation process of the positive plate are optimized,and the electrochemical corrosion rate of the grid is further reduced by controlling the positive electrode potential.Based on the Pb-Ca-Sn-Al quaternary alloy system,the effects of alloy composition on metallographic structure and electrochemical properties are studied.The results reveal that the corrosion resistance of the alloy can be significantly improved by increasing the Sn content of the alloy to above 1.5 wt.%.The alloys are modified by 9additives:Bi,Ba,Sr,Ge,Se,Ag,Yb,La.Sm.Bi,Ba,and Ge can promote the grain growth of the alloy,and Ag,Yb,La,and Sm can refine the grain size and induce the uniform distribution of the alloy.Bi,Ba,Ag,La,and Sm can effectively inhibit the growth and aggregation of Pb?II?and Pb O₂ in the corrosion layer of Pb-Ca-Sn-Al alloy,and the corrosion layers are uniform and dense with better conductivity.Bi,Ag,and La are selected as the better additives for mixing configuration.The electrochemical corrosion behavior of the alloy is studied by galvanostatic corrosion at high temperatures.All alloys containing La are corroded severely with a loose porous corrosion layer,and the creep elongation of the grids exceeds 10%.The weight loss of corrosion and the thickness of the corrosion layer of the Ag alloy grid are significantly reduced.The uniform and dense corrosion layer can prevent the substrate from being further corroded,and the creep elongation of the grid is not more than 1%.Therefore,the Pb-Ca-Sn-Al-Ag alloy is suitable for the positive grid of long-life lead-carbon battery.The electrochemical corrosion behaviors of lead paste-coated grids and bare grids are studied at different polarization times and polarization temperatures.Research studies indicate that the corrosion of the grid covered by the active material is well suppressed in the electrode plate compared to the bare grid,and the growth and cracking of the corrosion layer are better improved.Therefore,the double-sided smear technology can effectively suppress the corrosion of the grid caused by direct contact with the electrolyte.Two-component alloys are employed in lead-carbon batteries.Pb-Ca-Sn-Al-La alloy can effectively improve the deep cycle performance of the batteries,but the corrosion and creep of the grid lead to a shorter life of the floating charge.Pb-Ca-Sn-Al-Ag alloy has high corrosion resistance,but it is difficult to form a corrosion interface layer with an excellent grid/active material interface.The preferred corrosion-resistant causes the problem of the high impedance of the interface corrosion layer on the positive plate.The improvement of the grid interface is studied from three aspects:the grid pretreatment process,the electrode curing process,and the positive electrode additives,respectively.The multi-stage high-temperature curing process can effectively improve the bonding force and conductivity between the grid/active material.After 400 cycles of 100%DOD,the improved lead-carbon batteries present excellent cycle performance with a capacity retention rate of 98%.The method of reducing the corrosion rate of the grids is studied from the perspective of electrochemical corrosion kinetics.The working rule and mechanism of lead-carbon battery positive electrode are studied.It can be demonstrated that the positive electrode potential increases with the increase of the So C during the charging process.When the state of charge of batteries reaches 90%,the positive electrode potential reaches the maximum value.The positive potential of a lead-carbon battery undergoes an upward trend as the number of cycles increases.The effect of electrode potential on the electrochemical corrosion rate of the grid is studied.The electrochemical corrosion rate increases with increasing potential.When the potential is higher than 1.2 V,the growth rate of electrochemical corrosion increases obviously.The effective measures to influence the positive potential of the lead-carbon battery are explored by studying battery design and application.The effects of the carbon materials in the negative electrode,the additives of the positive electrode,electrolyte concentration,and average charging voltage on positive electrode potential are studied.The hydrogen evolution overpotential of the negative electrode decreases with the introduction of 0.2 wt.%activated carbon,which increases the charging potential of the positive electrode for the new battery by approximately 41 m V.However,the carbon material reduces the electrochemical polarization of the negative electrode so that the increase in potential is suppressed during the discharge process.The addition of 0.1 wt.%Sb₂O₃ and 0.1 wt.%Sn SO₄ can increase the content of?-Pb O₂ in the positive electrode.The positive electrode potential decreases with the decrease of ohmic polarization and electrochemical polarization during the charging process.The positive electrode potential can be effectively reduced by reasonably reducing the electrolyte concentration of the lead-carbon battery and water loss.By reducing the equalizing charging voltage of 50 m V in the process of the lead-carbon battery cycle,there is no significant impact on the capacity maintenance ability of the battery after 1600 cycles.However,it can reduce the overcharge and side reactions of the positive electrode,and significantly alleviate the corrosion of the positive electrode grid and the softening of the positive lead paste,which is beneficial to prolong the life of the lead-carbon battery.