Application and performance optimization of microwave-synthesized nano-lead-carbon materials in electrode active materials of spent lead-acid batteries

Abstract

Direct recycling of lead paste from waste lead-acid batteries faces significant challenges, primarily due to the poor electrochemical performance and low conductivity of recycled lead oxide materials, and their susceptibility to severe irreversible sulfation under high-rate partial charge conditions. To address this issue, a highly efficient and low-cost microwave-assisted carbothermal reduction method was proposed. Using recycled lead oxide from lead-acid batteries as a precursor and graphitized carbon black as a carbon source, a nano-lead-carbon composite material is synthesized in situ in a one-step process. Key process parameters, including carbon source type, microwave power, and irradiation time, are systematically optimized, and its electrochemical performance is compared with that of pure recycled lead and a mechanically mixed control group. The results show that the optimized material forms a uniform nanocomposite structure with a lead grain size of only 44.73 nm and a specific surface area of 85.31 m²/g. This structure endows the material with excellent electrochemical kinetics, with a charge transfer resistance of only 8.19 Ω·cm², which is 18.4 times lower than that of Control-PbO. In rate performance testing, the nano-lead-carbon composite material exhibits a 1 C capacity as high as 118.17 mAh/g. This study confirms that the microwave method is an effective way to achieve high-performance, high-value reuse of waste lead paste, providing a technical solution with significant industrial application potential for closed-loop recycling of waste lead-acid batteries and low-cost manufacturing of lead-carbon batteries.