Lead phosphate prepared from spent lead compounds as a negative additive for lead-acid batteries

Agglomerated nanorods of lead phosphate have been synthesized from the reaction of lead acetate prepared from waste lead paste and Na 2 HPO 4 , which is used as an additive for the PbSO 4 -negative electrode of a lead-acid cell. It has been found that lead phosphate can be all converted to lead sulfate in 36 wt.% sulfuric acid electrolyte and generate phosphoric acid, and the negative active material containing 1 wt.% lead phosphate discharges a capacity of 111 mAh g −1 at 100 mA g −1 till 1.75 V; it still discharges 78 mAh g −1 after 1200 cycles, which is 10.1% higher than the blank PbSO 4 electrode. It is believed that phosphoric acid could remove the non-conductive oxide on the lead alloy grid; thus, a better conductive network could be built. Also, phosphoric acid is adsorbed on PbSO 4 particles, which can improve the reversibility of the electrode and diminish the shedding of PbSO 4 .