Study On Lead-acid Battery Manufacturing And Electrochemical Performance Of Novel Ultrafine Leady Oxide Made From Spent Lead Paste

Traditional leady oxides are mainly made via oxidation method from lead ingot throughtraditional pyro-metallurgical process. Then SO2and lead volatile particulates aregenerated as secondary pollutants. A novel leady oxide has been prepared by ahydrometallurgical leaching and low-temperature calcination process for recovering spentlead pastes in our group. It’s necessary to assess basic physiochemical characteristics ofleady oxide as electrode active material and test its electrochemical properties. In thisstudy, lead citrate Pb3（C6H5O7）23H2O was synthesized and crystalized from spent leadacid battery pastes via the citric acid-sodium citrate leaching system. The novel leadyoxides were prepared by the lead citrate precursor through calcination at350C,375C,400C,425C and450C for1h, respectively.（1） Effect of calcination temperature on the physicochemical properties of novel leadyoxidesThe self-synthesized leady oxides mainly comprise β-PbO, α-PbO and Pb, with particlesizes ranged from200nm⁵00nm. The properties of leady oxides change with thedifferent calcination temperatures. The results show that as temperature ascends over400C, the porous rod micro-structure of the particle turns to be granular and the fine leadyoxide granules start to agglomerate. As calcination temperature rises, leady oxide appearslarger apparent density, lower oxidizability, lower acid absorption value and lower waterabsorption value. Compared to traditional leady oxides, leady oxides prepared at375Cshows much smaller density of1.51g cm^-3and larger water absorption value of240mlkg^-1. Cyclic voltammetry results show that leady oxides prepared at375C with porousrod morphology and small particle size exhibit excellent initial electrochemicalperformance as positive active material.（2） Study on the battery manufacturing condition and reaction mechanism of leadyoxidesThe manufacture parameters of battery from novel leady oxide were listed as follows: inthe pasting process, the dosage of sulfur acid is45g/kg; the temperature and humidity ofmain curing program is proposed to be80C and97RH%for24h; when formation, the soaking step before constant current charging lasts for2h. In curing process,80C isbeneficial for the generation of4BS, while the step of temperature and humidity droppingis critical for the oxidization of Pb in green plate. When soaking, PbSO4particles generateand grow along with the3BS/4BS crystal. As soaking time increases, the surface of platebecome loose first and then more dense.（3） Effect of calcination temperature on battery performance of leady oxidesBattery testing results reveal that initial capacity and high-current discharge capacity oflead acid battery manufactured by self-synthesized leady oxides are better than those oftraditional lead acid battery. The20h rate and1C discharge time of self-synthesized leadyoxides have exceeded26h and40min, respectively. And the capacity mostly decreaseswith the calcination temperature. The concentration polarization impedance andelectrochemical impedance in the battery made by leady oxides at375C are small. Whileleady oxides prepared at over400C with the microscopic characteristics of tight ricegrain morphology and moderate particle size show good cycle performance. The capacityretention ratio of batteries made by leady oxides at450C have been maintained over70%after40charge-discharge cycles which can satisfy the particle use. The cycle performanceof novel leady oxide is to be promoted.In this study, the electrochemical properties and battery performance of novel leadyoxide recovered from spent lead acid battery paste by hydrometallurgical process has beenproved. The results in this thesis provide the evidence for application of novel ultra-fineleady oxides made from spent lead pastes, and a technical support for green recycling ofspent lead acid battery paste.