Exploring the Sodium‐Storage Mechanism of Nanosized Disodium Rhodizonate as the Anode Active Material

Abstract Nanosized disodium rhodizonate (Na₂C₆O₆, NCO) prepared by antisolvent crystallization is tested as an organic anode material for sodium‐ion batteries (SIBs). A reversible capacity of 230 mAh g⁻¹ combined with an excellent capacity retention of ≈85% after 1000 cycles versus Na/Na⁺ is demonstrated in a NaPF₆‐DME electrolyte. Such a promising electrochemical performance is achieved by the synergy of the NCO particle nanosizing, and the formation of a thin, but stable and Na⁺‐permeable solid electrolyte interface layer that builds‐up readily in the NaPF₆‐1,2‐dimethoxyethane electrolyte. The feasibility of the nanosized NCO anode for SIBs is also confirmed in a full sodium‐ion cell versus Na₃V₂(PO₄)₃ cathode, and the discharge potential is as high as 2.0 V suggesting a promising energy density.