Methanothermal reduction of mixtures of PbSO4 and PbO2 to synthesize ultrafine α-PbO powders for lead acid batteries

• PbO can be prepared by a solvothermal reaction of mixture of PbSO4 and PbO2 within methanol.
• The prepared PbO can discharge a capacity of 165 mAh g−1 at 5 mA g−1.
• The prepared PbO from “the spent” discharge a capacity of 170 mAh g−1 at 5 mA g−1.
• This paper shows a new way for the recycle of spent lead acid battery.

Three artificial mixtures of PbSO4 and PbO2 as well as the active materials obtained directly from the positive plates of spent batteries have been solvothermally treated in methanol at 140 °C for 24 h, which produce mainly PbO·PbSO4. The PbO·PbSO4 can be easily desulphated with ammonium carbonate to produce PbCO3, which can be calcined to form α-PbO to be used as positive active material of lead acid batteries. The α-PbO powders are irregular particles and highly electrochemically active, which discharges around 165 mAh g−1 at 5 mA g−1, 80 mAh g−1 at 200 mA g−1 and 60 mAh g−1 at 400 mA g−1 with excellent cyclic stability in 50 cycles. SEM investigations show that the as-formed PbO·PbSO4 may inherit and enhance the morphological characteristics of PbSO4, and carbonation of PbO·PbSO4 does not destroy the rod-like characteristics. For the active material from the positive plates of spent lead acid batteries, the discharge capacities are 170 mAh g−1 at the current density of 5 mA g−1, and 60 mAh g−1 at 400 mA g−1, which is also similar. In 50 cycles, its capacity loss is only 5%.

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