Improvement of the soluble lead battery using a novel recovered electrolyte

Abstract

The soluble lead battery is one of the redox flow batteries that are suggested for MWh energy storage to assist with the integration of sustainable energy sources as well as to bring electricity to areas with no grid connection. The soluble lead battery has several advantages including the fact that it uses the same electrolyte both sides, which should reduce the need for expensive membrane separators and reduce the number of tanks and circulating pump sets to one each, reducing complexity. However, research has shown that the positive electrode redox couple has limited reversibility and as such, results in build-up of material on the positive electrode, which consequently affects stripping at the negative electrode, and results in short circuits and short cycle life. This thesis enhances the advantages of the soluble lead battery by introducing a novel method to produce electrolyte for the soluble lead battery directly out of spent lead acid batteries. By so doing the thesis introduces an inexpensive method to make electrolyte for the battery, improving the battery’s competitiveness. The thesis also proves that the reagent grade electrolyte that is traditionally used in prior studies has nickel impurities in it and is as such harmful to the operation of the battery. Furthermore, the recovered electrolyte made out of spent lead acid batteries is cycled extensively in both static and flow cells to compare performance, and the recovered electrolyte is found to perform better than the reagent grade electrolyte in both cells. Hence based on the results, it is recommended that the soluble lead battery should use recovered electrolyte to avoid the detrimental effects of nickel in reagent grade electrolyte, as well as to take advantage of the relatively easy method of making recovered electrolyte, which takes advantage of the refined lead in lead acid batteries as well as the additives traditionally added to enhance operation in traditional lead acid batteries. To further improve the performance of the soluble lead battery, cycling regimes are carried out using recovered electrolyte, where it is found that current density, the inter-electrode gap, as well as the end-of-discharge voltage, have a significant effect on the performance of the soluble lead cell, and need to be controlled to optimise cycle life as well as charge, energy and voltage efficiency. Finally, further work is recommended to address questions that arose and that could not be addressed within the scope of this work.

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ORCID for Andrew Cruden: orcid.org/0000-0003-3236-2535

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