| The traditional methods of lead recycling from spent lead acid battery pastes are the pyrometallurgical processes, which emit SO2 and lead volatile particulates. Our research group has developed a new hydrometallurgical approach to recycle lead from spent lead pastes. Ultrafine leady oxide powder, with physicochemical properties different from traditional products of pyrometallurgical processes, can be obtained by the new methods. Therefore, the traditional parameters for lead acid battery manufacture are not suitable in terms of the ultrafine leady oxide powders. The manufacture parameters of grid pasting and soaking were studied in this thesis. The impacts of these parameters on lead acid battery with the ultrafine leady oxide powders was explored and the most essential factors were found different from that with traditional leady oxide powders. What's more, ultrafine leady oxide powders were applied in the lead acid redox flow batteries. Since the electrolyte compositions have great influences on the redox flow batteries' performances, the optimal electrolyte composition for the lead electrodeposition and electodissolving processes was identified. During the tests with electrolyte made by ultrafine leady oxide powders, the transference of impurities was also studied.1. The influence of acid content for pasting on the phase transformation, micromorphology and electrochemical properties of PAMThe acid content for pasting has great impact on the lead paste in later processes. With increasing the acid content, the content of 3BS in lead paste after curing increased firstly and then decreased. When acid content was 9 wt%, the content of 3BS was the most. After formation, the content of PbO2 in lead paste decreased with increasing acid content, which means that PbO2 in lead paste was the most when acid content was the least(5 wt%). The size of PbO2 particles diminished firstly and then enlarged with further increasing acid content for pasting. When acid content was 9 wt%, that size of PbO2 was the minimum. The trend of initial capacity of battery was related to the content of PbO2. When acid content was the least, initial capacity was the most, which could reach 3.2 Ah.2. The influence of soaking condition on the phase transformation, micromorphology and electrochemical properties of PAMDuring the soaking process, the components of lead paste(3BS and PbO) after curing transferred to PbSO4. With increasing soaking time and the soaking acid density, the transfer speed also increased. Compared to traditional leady oxide powders, it was much faster to transfer ultrafine powders. After formation, the PbO2 content in lead paste would reduce when the soaking acid density was too high(1.150 g/cm3), as well as when soaking time was increased. When ultrafine leady oxide powders were adopted, the effects of formation was better than that with traditional leady oxide powders. High soaking acid density(1.150 g/cm3) was harmful to the battery cycle stability. When soaking acid density decreased, the influence of soaking time became stronger. Long soaking time had negative impact for battery with high soaking acid densities(1.100 g/cm3 and 1.150 g/cm3). While with the relatively low soaking acid density, lead paste needed a longer soaking time. When the soaking acid density was 1.050 g/cm3, cycle stability of batteries were the best, which still had 75 % of initial capacity after 80 cycles.3. The optimization of electrolyte composition for lead acid redox flow battery synthesized using ultrafine leady oxide powdersThe electrolyte composition has essential influences on the physical and electrochemical properties of soluble lead redox flow battery. Increasing the contents of Pb2+ and CH3SO3 H resulted in higher kinematic viscosity of the electrolyte. When Pb2+ was 0.5 mol/L, ionic conductivity reached the summit and then reduced with the further increasing Pb2+ content. Both the concentrations of CH3SO3 H and Pb(CH3SO3)2 were found responsible for the equilibrium potential shifts and exchange-current density variations. During constant current charge-discharge measurement, the specific capacity of the Pb2+/Pb electrode was about 253 mAh/g(98 % of the theoretical value). Therefore, the optimal composition of electrolyte was 0.5 mol/L CH3SO3 H and 1.5 mol/L Pb(CH3SO3)2. When such electrolyte made with ultrafine leady oxide powders was examined, between the performances of recycled sample electrolyte and the reagent grade electrolyte exhibited no difference, indicating that the impurities was hardly involved in the reactions.In this study, the influences of the acid content in pasting and soaking conditions on the properties of lead paste were studied, providing a technical support for developing battery manufacture processes suitable for ultrafine leady oxide powders. In addition, it proved feasible to apply ultrafine leady oxide powders in lead acid redox flow batteries. |
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