Study On The Influence Of Electrolyte Additives On The Performance Of Lead-acid Battery Made From Novel Leady Oxides

Lead is the main component of spent lead acid battery （approximately counts for60%）.In traditional pyrometallurgical recycling process of spent lead paste, the emission of SO2and lead dust cannot be avoided. A new hydrometallurgy method has been proposed torecycle lead. The objective product, novel ultrafine lead oxide, was prepared via a lowtemperature calcination of lead citrate, which was prepared by citrate and sodium citrateusing spent lead acid battery paste as starting materials. This paper was focused on theeffect of SnSO₄and Na₂SO₄as electrolyte additives on electrochemistry performance ofnovel lead acid battery. The content of this thesis contains following three parts:1. Preparation of lead oxide by decomposition of lead citrateLead citrate precursor （obtained at pH of4.96, temperature of50oC and crystallizationfor20h）, was utilized to prepare lead oxide by using different calicination furnace. Thelead oxide prepared in a tube furnace, has a better PbO proportion, better absorptions ofwater, better absorptions of acid and lower density. The as-prepared novel lead oxide hasPbO proportion of75-87%and particle size below5μm. Such lead oxide exhibitsexcellent initial electrochemical performance, which is beneficial to fabricate batteries, asneedle shaped PbO2can be obtained in the formation process.2. The effect of SnSO₄and Na₂SO₄on the electrochemical performance of the leadelectrodeCV results show that when addition of SnSO₄in electrolyte, both the reduction peakcurrents and oxygen evolution currents increase first and then decrease, with a highestcharge/discharge rate of90%after cycling50times. The large PbSO₄particles becomesmaller with the increase of SnSO₄. CV results show the same trend as SnSO₄inelectrolyte when addition of Na₂SO₄.3. Th effect of SnSO₄and Na₂SO₄on the battery performance of lead oxideWith the optimal addition of SnSO₄in electrolyte of2.24mmol/L, the capacityretention ratio of2A h battery assembled in the study maintains over70%after40charge-discharge cycles. The double-layer capacitor of the battery rises with the increaseof SnSO₄, thus causing the increase of initial discharge capacity. The PbO2content in the plate dismantled from batteries reaches the maximun of78.4%in the optimal addition ofSnSO₄. The initial discharge capacity of the battery with addition of Na₂SO₄reach themaximun value of2.23A h with addition of0.35mmol/L, the capacity retention ratio keepthe best with addition of0.07mmol/L （the initial discharge capacity is2.21A h）.4. The effects of soaking time on the battery performanceAs the soaking time in sulfuric acid affects formation process of the plate, the effect ofdifferent soaking times （0.5h,1h and2h） on the battery performance was investigatedrespectively. When the soaking time is1h, the PbO2particle becomes smaller with thehighest content of PbO2. The initial discharge capacity of the battery is highest. When thesocking time increases, the discharge capacity fluctuates, resulting from nonuniform PbO2particles.The research in this paper could offer some references on fabricating high performancebattery by using this novel lead oxide recycled from spent lead acid battery paste.