Organic‐Carbon Core–Shell Structure Promotes Cathode Performance for Na‐Ion Batteries

Abstract

Abstract The organic‐carbon core‐shell structure is constructed for the cathode material of [ N , N' ‐bis(2‐anthraquinone)]‐perylene‐3,4,9,10‐tetracarboxydiimide (PTCDI‐DAQ, 200 mAh g −1 ) through an interesting strategy called the surface self‐carbonization. As expected, the organic‐carbon core–shell structure (PTCDI‐DAQ@C) can endow PTCDI‐DAQ the outstanding cathode performance in Na‐ion batteries. In half cells using 1 m NaPF 6 /DME, PTCDI‐DAQ@C can maintain 173 mAh g −1 for nearly one year, while PTCDI‐DAQ quickly decreases from 203 to 121 mAh g −1 only after 100 cycles. Meanwhile, the constructed Na‐ion full cells with the Na‐intercalated hard carbon anode can deliver the peak discharge capacity of 195 mAh g −1 cathode and the high median voltage of 1.7 V in 0.9–3.2 V, corresponding to the peak energy densities of 332 Wh kg −1 cathode and 184 Wh kg −1 total mass , respectively. Notably, the electrode materials only include the very cheap elements of C, H, O, N, and Na. Furthermore, the Na‐ion full cells can also show the very impressive high‐temperature (197 mAh g −1 cathode at 50 °C) and subzero (185/90 mAh g −1 cathode at −10/−40 °C) performances, respectively. To the best of the authors’ knowledge, the comprehensive properties of the Na‐ion full cells are the best results based on organic cathodes.