All-organic rechargeable batteries may have low cost, materials sustainability and environmental friendliness, particularly suitable for large scale electric energy storage applications. However, development of such a new generation of batteries is now hindered by the lack of appropriate organic anode materials. In this paper, we report a novel polythiophene/carbon composite, where n-dopable poly (3,4-dihexylthiophene) is in situ chemically polymerized on carbon nanofibers. This organic-carbon composite exhibits an exceptionally high reversible electrochemical capacity of ∼300mAhg−1 (or ∼ 200AhL−1) through n-type redox reactions and superior capacity retention of ⩾95% after a hundred cycles. Based on this n-type redox-active material, an all-organic Li-ion cell using polytriphenylamine as cathode-active material was constructed and found to operate successfully, demonstrating possible applications of this composite as a high capacity anode material for all-organic storage batteries.