Abstract: In order to improve the irreversible sulfation and hydrogen evolution of the negative electrode of lead-acid batteries, in this study, the olypyrrole coated with conductive carbon black/indium oxide composite PPy@(C/In₂O₃) were prepared by in-situ oxidation polymerization on C/In₂O₃. The composite materials were characterized by SEM, FTIR, BET and XRD. The electrochemical performance of the composites was analyzed by CV and LSV. Finally, the PPy@(C/In₂O₃) composite materials were added in the negative active material of lead-acid batteries. The effect of composite materials on the high-rate partial-state-of-charge (HRPSoC) performance of lead-acid batteries was investigated. The results show that the PPy@(C/In₂O₃) retain the structural feature of C, and have larger specific surface area than PPy, and have higher hydrogen evolution over-potential and capacitance than C. When PPy@(C/In₂O₃) composite materials were added to the negative active material of the lead-acid batteries, it can not only reduce the internal resistance of the negative plate and inhibit the negative sulfation problem of the batteries, but also reduce the hydrogen evolution problem of the negative electrode of the batteries. At the same time, the discharge capacity significantly improves the cycle life of the lead-acid batteries under the HRPSoC operation. Finally, the lead-acid batteries containing the negative plate of PPy@(C/In₂O₃) show excellent HRPSoC cycle life which increased by 1.78 times compared with the cycle life of the blank battery.