A polyanionic anthraquinone organic cathode for pure small-molecule organic Li-ion batteries.

Sodium 9,10-anthraquinone-2,6-disulfonate (Na 2 AQ26DS, 130 mAh g−1) with polyanionic character and two O–Na ionic bonds is used as an organic cathode for Li-ion batteries. Na 2 AQ26DS exhibits highly impressive cycle stability in ether electrolytes due to its polyanionic character and the effective suppression of solvent-molecule co-intercalation. In half cells (1–3.9 V vs. Li+/Li) using 1 M bis(trifluoromethanesulphonyl)imide lithium salt (LiTFSI) in 1,3-dioxolane/dimethoxyethane (DOL/DME), Na 2 AQ26DS delivers a highly stable specific capacity of 123 mAh g−1 at 50 mA g−1 for 900 cycles (6-month test) and realizes ∼69 mAh g−1 for 2800 cycles at 500 mA g−1. In the full cells with the reduced state (Li 4 TP) of lithium terephthalate (Li 2 TP) as the organic anode, the resulting Li 4 TP II Na 2 AQ26DS organic lithium-ion batteries (OLIBs) can display a highly stable average discharge capacity of 120 mAh g−1 cathode for 100 cycles at 50 mA g−1 and ∼63 mAh g−1 cathode for 1200 cycles at 500 mA g−1 in 0.2–3.3 V. A polyanionic organic cathode of sodium 9,10-anthraquinone-2,6-disulfonate (Na 2 AQ26DS, 130 mAh g−1) is reported for pure-organic Li-ion batteries. [Display omitted] • Polyanionic Na 2 AQ26DS is a new organic cathode for Li-ion batteries. • Na 2 AQ26DS delivers high stability in the ether electrolytes for 6 months. • Na 2 AQ26DS delivers a reversible capacity of 138 mAh g−1 in half cells. • Organic Li-ion batteries are built using lithium terephthalate anode. • Na 2 AQ26DS delivers an average capacity of 120 mAh g−1 in full cells. [ABSTRACT FROM AUTHOR]