Air-Stable High-Voltage Li-Ion Organic Cathode Enabled by Localized High-Concentration Electrolyte

While lithium-ion batteries have revolutionized the field of energy storage, their reliance on critical minerals such as cobalt and nickel raises significant concerns over resource availability and supply chain uncertainty. In this study, we revisit dithiin-fused dilithium naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) (DNP-Li) as a high-voltage Li-ion organic cathode and evaluate its performance in conjunction with localized high-concentration electrolyte (LHCE). DNP-Li exhibits remarkable air and thermal stability, a high operating potential of 3.55 V vs. Li⁺/Li, and a specific capacity of 232 mAh g^-1, positioning it as one of the most promising candidates among Li-ion organic cathodes. Furthermore, the electrochemical behavior of DNP-Li is strongly influenced by the electrolyte composition, giving distinct two-plateau or four-plateau voltage profiles accompanied by reversible or irreversible phase transitions in carbonate-based or LHCE electrolyte formulations, respectively. The reduced solubility of DNP-Li-based redox intermediates in LHCE enhances cycling stability, achieving a capacity retention of 85% after 50 cycles at 0.1C and 75% after 160 cycles at 0.5C, demonstrating a significant improvement compared to the carbonate-based electrolyte. This work highlights the critical role of solute-electrolyte interactions in modulating the electrochemical performance of multielectron small-molecule organic cathodes, offering new pathways for advancing sustainable and high-efficiency energy storage technologies.