Construction of fully conjugated pyrazine derivative organic cathode for high-rate and long-lifetime lithium-ion batteries

Redox-active small-molecule organic compounds have been widely studied as promising electrode materials for lithium-ion batteries (LIBs) due to their high theoretical capacity. However, severe dissolution problem and unfavorable electronic conductivity still limit their wide application. Herein, we design and synthesize an organic cathode material by a simple dehydration condensation, i.e., pyrazino[2, 3- b] bispyrazino[2″, 3″:5′, 6′] pyrazino[2′, 3′- f:2″, 3″- h] quinoxaline (HAPN). A fully conjugated multi-pyrazine-based structure provides abundant redox-active sites for high Li-storage capacity. It strengthens π–π interactions, leading to rapid electron transfer and ideal structural stability. Additionally, the unique porous feature and highly extended N-rich aromatic structure provide sufficient channels for rapid electrochemical kinetics. Therefore, HAPN as cathode for LIBs exhibits high Li-storage capacity (282 mAh g −1 at 0.1 A g −1 ), remarkable cycling stability (112 mAh g −1 at 0.5 A g −1 even over 1000 cycles), and superior rate capability (86 mAh g −1 at 10 A g −1 ). Additionally, by ex situ spectra analysis and theoretical calculations, the Li-storage mechanism of the HAPN cathode was revealed and understood in depth. This molecular design and detailed mechanism analysis provide essential insights into the development of advanced organic cathodes for next-generation batteries.