Sodium 9,10-anthraquinone-2,6-disulfonate (Na 2 AQ26DS), with polyanionic character and two OÀNa ionic bonds, is found to be ah ighly stable organic cathode in Na-ion batteries, delivering capacities of approximately 120 mAh g À1 for 300 cycles (50 mA g À1 )a nd around 99 mAh g À1 for 1000 cycles (1 Ag À1 ). These resultsa re the best performance reported to date for small-molecule, anthraquinone-basedo rganic cathodes in Li-, Na-, or K-ionbatteries.The rapidly-growing demands for electric vehicles anda"smart grid" require large-scale applicationso fr echargeable batteries.[1] Therefore, electrode materials in batteries that are low in cost, free of resourcel imitations, and environmentally friendly are highly desirable . [2] At present,r echargeable Li-ion batteries are approaching the ceiling of their energy density. [3] Moreover, the limited resources of Li (0.0017 wt %f or Li in the Earth's crust) and of the rare metals contained in cathodes, such as Ni, Co, Mn, also impedet heir large-scale application. [4] Organic electrode materials with extremelyl ow costs have attractedm ore and more attention as promisingn ext-generation energy-storagem aterials. More importantly,o rganic electrodes have been found capable to store abundant, cheap, and large-radius metal ions, such as Na + ,K + ,a nd Mg 2 + . [5] There are two main concerns for organic electrode materials under consideration for practical application. One is that organic electrode materials usually suffer from poor electronic conductivity and thus give unsatisfactory rate performance. [6] However,this problem can be largely solved by careful technological modifications. The other is that small-molecule organic materials, particularly for high-capacity organic cathodes, [7] show significant solubility in organic liquid electrolytes, [8] ultimately leadingt ot he poor cycling stability of organicb atteries.