Isomer Engineering toward High-Voltage and Air-Stable Organic Cathodes for Lithium-Ion Batteries

Organic cathode materials based on abundant elements are promising candidates for next-generation batteries due to their structural flexibility, high theoretical capacity, and environmental friendliness. However, lithiated organic cathodes typically suffer from low redox potential and poor air stability, which limit their practical application. Herein, we demonstrate that the redox potential of lithiated organic materials can be significantly enhanced by precisely tuning the substitution pattern of functional groups. We have synthesized and investigated two isomeric lithiated tetracenequinone derivatives, lithium 5,12-dioxo-5,12-dihydrotetracene-1,4-bis(olate) (Li2-1,4-DHTQ) and lithium 6,11-dioxo-6,11-dihydrotetracene-5,12-bis(olate) (Li2-6,11-DHTQ), with identical chemical formulas but differing functional group configurations. Li2-1,4-DHTQ manifested good air stability, stable cycling performance, and an average discharge plateau voltage of about 3.3 V, which was 900 mV higher than that of Li2-6,11-DHTQ. Li2-1,4-DHTQ exhibited an 83% capacity retention after 200 cycles at 100 mA g–1 with a PVDF-based solid polymer electrolyte. This work provides a molecular design strategy to simultaneously achieve high voltage and air stability in organic cathodes through isomer engineering.