Design of a bipolar organic small-molecule cathode with mesoporous nanospheres structure for long lifespan and high-rate Li-storage performance

• Published in: Chemical science (Cambridge) Vol. 15; no. 3; pp. 151 - 16
• Main Authors: Wang, Simin, Guo, Qifei, Liu, Haoran, Zhang, Longhai, Zhang, Chaofeng, Zhou, Tengfei, Ma, Quanwei, Li, Hongbao, Wang, Rui, Zheng, Yang
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 17.01.2024; Royal Society of Chemistry; The Royal Society of Chemistry
• Subjects: Cathodes; Chemical synthesis; Chemistry; Chemistry, Multidisciplinary; Diamines; Electric potential; Electrode materials; Ion diffusion; Ion storage; Life span; Lithium-ion batteries; Molecular structure; Nanospheres; Physical Sciences; Rechargeable batteries; Science & Technology; Synchrotrons; Voltage; POLYMERS
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d3sc05843c

Organic small-molecule compounds have become promising cathode materials for high-performance lithium-ion batteries (LIBs) due to their high theoretical capacity, efficient utilization of active sites, low cost, and sustainability. However, severe dissolution and poor electronic conductivity limit their further practical applications. Herein, we have synthesized an insoluble organic small molecule, ferrocenyl-3-(λ 1 -azazyl) pyrazinyl [2,3- f ] [1,10] phenanthrolino-2-amine (FCPD), by grafting ferrocene onto pyrazino[2,3-f] [1,10] phenanthroline-2,3-diamine (PPD). The combination of ferrocene (p-type Fe 2+ moiety) and PPD (n-type C&z.dbd;N groups) in a bipolar manner endows the target FCPD cathode with an increased theoretical capacity and a wide voltage window. The highly conjugated π-π aromatic skeleton inside enhances FCPD's electron delocalization and promotes strong interaction between FCPD units. Additionally, the mesoporous structure within the FCPD can provide numerous electroactive sites, contact area, and ion diffusion channels. Benefiting from the bipolar feature, aromatic, and mesoporous structure, the FCPD cathode demonstrates a large capacity of 250 mA h g −1 at 0.1 A g −1 , a long lifespan of 1000 cycles and a high-rate capability of 151 mA h g −1 at 5 A g −1 along with a wide voltage window (1.2-3.8 V). Additionally, in situ synchrotron FT-IR and ex situ XPS reveal its dual ion storage mechanism in depth. Our findings provide essential insights into exploring the molecular design of advanced organic small molecules. We designed a bipolar organic small-molecule cathode ferrocenyl-3-(λ 1 -azazyl) pyrazinyl [2,3- f ] [1,10] phenanthrolino-2-amine (FCPD). This unique molecular design successfully boosts its Li + /anion storage performance.