Low-grade lignite derived nitrogen doped hierarchical porous carbon for advanced lead-carbon batteries

Abstract

The addition of carbon materials to the negative electrode would inhibit sulfation and prolong the cycle life of the lead-acid batteries. However, carbon materials contribute to the emergence of hydrogen evolution reaction (HER) and loss of water on the negative electrode. Accordingly, low-grade lignite raw material was one-step pyrolyzed to prepare nitrogen doped porous carbon (LNC) materials, which were further employed as negative additives to mitigate the above issues. The as-prepared LNC delivered large specific surface area (SSA) in the range of 1675.0–2503.3 m2 g−1, micro-mesoporous hierarchical structure, and high nitrogen doping level. Nitrogen doping considerably inhibited the HER and promoted the conversion kinetics between PbSO4/Pb in the negative electrode. Besides, the cycling life of lead-carbon battery containing LNC-1/3 at high-rate partial state of charge reached 9100 cycles, which reflected a 5.5-fold improvement over the blank. The improved performance could be attributed to the large SSA and plentiful functional groups, which offer active sites for the conversion of active substances, construct abundant ion channels, and refine the PbSO4 particles, thereby successfully minimizing irreversible sulfation. The short-route synthesis method provides a feasible approach to the reutilization of low-grade lignite, reflecting the circular economy.