Suppressing hydrogen evolution and eliminating sulfation in lead-carbon batteries via potential-matching g-C3N4@rGO nanosheets

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 474; p. 145880
• Main Authors: Tao, Daiwen, Liu, Xiong, Huang, Simiao, Li, Zeming, Yang, Hui, Wang, Jinyu, Zhang, Qilong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2023
• Subjects: Electrical double-layer capacitors; g-C3N4@rGO; Lead-carbon battery; Sulfation; Suppressing hydrogen evolution; g-C3N4@rGO; Electrical double-layer capacitors; Lead-carbon battery; Suppressing hydrogen evolution; Sulfation
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.145880

[Display omitted] •The lower limit of working potential of rGO was extended from −0.3 to −0.9 V by g-C3N4 modification.•The potential mechanisms for suppressed-HER and increased-capacitance were elucidated.•The link between the EDLCs and HER was established through two micro kinetic processes.•The lifetime of LCBs was increased to 3.2 times through potential-matched g-C3N4@rGO additive. Hydrogen evolution reaction (HER) and sulfation on the negative plate are main problems hindering the operation of lead-carbon batteries under high-rate partial-state-of-charge (HRPSoC). Here, reduced graphene oxide nanosheets modified with graphitic carbon nitride (g-C3N4@rGO) were prepared and used as additives in an attempt to solve the above bottleneck. Galvanostatic charge–discharge (GCD) curves show that immobilization g-C3N4 on rGO surface can extend the lower limit of working potential of rGO from −0.3 to −0.9 V, which better matches the working potential range of Pb/PbSO4 redox pair. Theoretical calculations and correlation analyses show that HER can be linked to electrical double-layer capacitors (EDLCs) through two micro kinetic processes: namely, the desorption process of H+ from additive and the migration process of e− reaching additive surface, and that g-C3N4 modification strategy can suppress the HER on the rGO surface while increasing the capacitance of EDLCs. Meanwhile, potential-matched g-C3N4@rGO (θ = 35.76°) is more hydrophilic than pure rGO (118.20°), so the use of g-C3N4@rGO as a battery additive can eliminate sulfation of the negative plate by promoting electrolyte penetration and increasing capacitance contribution. Therefore, the electrochemical performance of g-C3N4@rGO-modified batteries showed a significant improvement over their counterparts, indicating this work is a good attempt.