Revealing the mechanism of Faradaic PN junction design strategy in enhancing electrochemical performance of supercapacitor

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 488; p. 150981
• Main Authors: Chen, Rongxin, Cai, Xiaoyi, He, Xinyu, Zhang, Tengyi, Eldona, Calvin, Zhang, Qi, Cheng, Li, Shen, Ze Xiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2024
• Subjects: Built-in Electric Field; Fermi level; Layered double hydroxide; PN junction; Supercapacitor; Supercapacitor; Built-in Electric Field; Fermi level; PN junction; Layered double hydroxide
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2024.150981

[Display omitted] •Utilized a simple hydrothermal method to create PN junction composites.•Proved enhanced Faradaic activity via charge redistribution at interfaces.•Reduced band gap enhanced LDH material conductivity.•Investigated charge transfer pathways during charging/discharging. Heterostructure materials, owing to their unique interfaces, robust structures, and synergistic effects, are increasingly garnering attention for their potential to enhance the energy/power output and lifespan of energy storage devices. Nonetheless, the intricate relationship between the band theory of heterostructures and their design strategies still demands further exploration. In this study, a binder-free NiCo2O4@NiCoAl-layered double hydroxide (LDH) PN junction cathode was constructed through a straightforward hydrothermal reaction. Extensive characterization and first-principles calculations have substantiated that the redistribution of charge within the space charge region considerably boosts the Faradaic activity and augments the conductivity of the LDH component, demonstrating an impressive specific capacitance of 1434.0 C g−1. Furthermore, the analysis focusing on the width of the space charge region has shed light on the charge transfer mechanism during charging and discharging, thereby validating the efficacy of the PN junction material design strategy. This research underscores the pivotal role of semiconductor theory in heterostructures and illuminates the potential of Faradaic PN junction composite materials in battery-type energy storage applications.