1-Aminoanthraquinone as an electro-polymerizable additive to improve the cycling performance of a Na3V2(PO4)2F3 cathode

•A small amount of AAQ was used as an electro-polymerizable additive.•AAQ was electrochemically oxidized to form a thin conductive polymer on cathode.•The conductive layer enhanced the cycling performance of Na3V2(PO4)2F3 cathode. A small amount of 1-aminoanthraquinone (AAQ) was used as an electro-polymerizable additive in a liquid electrolyte. AAQ was electrochemically oxidized to form a thin conductive poly(1-aminoanthraquinone) (PAAQ) layer on a sodium-ion cathode material, Na3V2(PO4)2F3 (NVPF), at approximately 4.0 V during the initial charging processes. The resulting PAAQ layer provided an effective conduction pathway in the NVPF electrode, and thus enhanced the cycling performance in terms of the discharge capacity, cycling stability and rate capability. Our study demonstrates a simple and efficient approach to boost the electrochemical performance of a NVPF cathode for sodium-ion batteries.