Fabrication Of High Performance PbSO₄ Negative Electrode Of Lead-acid Battery

Lead-acid batteries（LABs）with a history of more than 160 years have made outstanding contribution to the development of industrialization in the world.Nowadays,LABs still play an important role in the industrial production and daily life because of their advantages of safety,cost effectiveness,mature production technology,as well as relatively complete recycling system.In recent years,with the increasing radius of people’s activities,fossil energy is consumed in large qugntities,resulting environmental problems more prominent.The electric moped,hybrid and pure electric vehicle industries come into being.LABs are cost-effective,which are popular with ordinary people.Therefore,the production and sales of LABs have continued to increase over the years.However,people also put forward higher requirements for battery performance.Compared with lithium-ion batteries,LABs have low energy density and short cycle life,limiting the use of LABs in ordinary passenger vehicles.However,if the LABs are used as fixed energy storage devices for renewable energy,the disadvantange of low energy density can be avoided.Unfortunately,the problem of consistency and short cycle life have to be solved in the large-scale use.Over the years,people have been committed to improving the discharge capacity of LABs by developing new electrode materials and using various additives.Although the recycling of the spent LABs through the metallurgical process has been industrialized,it causes environmental concerns and high energy consumption.It is disappointing that the profit margin of the LABs industry is low caused by the above problems.In the past more than ten years,our team has been carrying out research on recycling procedures banning any metallurgical processes.The method of producing electrochemically active uniform lead sulfate or basic lead sulfate in a 100%resource-recycling manner from waste batteries and using them to manufacture high-performance and high-consistency LABs has been determined.However,the adhesion between PbSO₄ particles is not as good as traditional lead power,causing the active materials to fall off during the preparation process of PbSO₄ electrode,which increases the difficulty in preparing the electrode.In this paper,the conductive adhesive were prepared by using organic polymer polyvinyl alcohol（PVA）and sodium polystyrene sulfonate（PSS）mixed with carbon materials and used as an additive for lead sulfate negative electrode to improve the mechanical properties and capacity.The main rusults are as follows.（1）Preparation of conductive adhesive.The PVA and PSS as binders was added to the mixed carbon materials,following by making uniform paste.Finally,the paste was pressed into a conductive adhesive sheet.Four groups sheets with higher conductivity and hydrogen evolution potential were selected from the 9 groups of conductive adhesive formulations.The binders amounts of the four groups are:0.3%PVA+0.2%PSS、0.3%PVA+0.6%PSS、0.4%PVA+0.4%PSS、0.5%PVA+0.2%PSS（based on the quality of lead sulfate used in the negative plate,the same as below）;（2）Determination of electrode manufacturing process.The following three mixing methods were used.Method 1,Firstly,the active materials are mixed with the conductive agent,then the banders was added.Method 2,Firstly,the binders and the conductive agent were mixed,and then,the active materials was added.Method 3,Firstly,the binders and the active materials were mixed,and then,the conductive agent was added.The results of the SEM images of the electrodes,as well as discharge performance of the batteries show that Method 3 is best.The test method commonly used in the industry is used to detect the effect on the mechanical property of the electrode.The results show that the binders can effectively improve the mechanical strength of the PbSO₄ electrode.（3）The influence of conductive glue on the electrochemical performance of lead sulfate electrode.The four groups of conductive glue with excellent performance were selected as additives for lead sulfate electrode,and the best manufacturing method was used.When the amount of binders is 0.5%PVA+0.2%PSS,the electrode can reach a stable discharge specific capacity of about 110 m Ah·g^-1 and survives 700 cycles at 100%discharge depth at 100 m A×g^-1.It is worth mentioning that the addition of PSS can effectively shorten the activation time of batteries.It takes about 20 cycles to reach a stable capacity for electrodes without PSS.However,when PSS is present,the electrodes can achieve a higher stable discharge specific capacity only after 5～8 cycles.（4）To explore the feasibility of using binders PVA and PSS to replace the sodium lignosulfonate as an additive for PbSO₄ negative electrode.The results show that the capacity of the electrodes with binders are higher than that of the electrode with sodium lignosulfonate.In the rate test,the electrodes added binders have excellent cycle stability.Therefore,the sodium lignosulfonate can be replaced by the conductive glue as an additive for PbSO₄ negative electrode.