Rational design of high-performance sodium-ion battery anode by molecular engineering of coal tar pitch

Carbon frameworks with appropriate micro- and macrostructure as well as chemical composition are prepared from aromatic coal tar pitch via a combined approach of molecular structure design and facile salt template method. When used as sodium-ion battery anode, the enlarged interlayer distance benefits sodium ion insertion/extraction and the interconnected nanosheets structure not only facilitates the contact of electrolyte but also shortens the sodium ion diffusion path. Additionally, the chemisorption of the sodium ion with nitrogen and oxygen containing functional groups on surface can further improve the electrochemical performance. The carbon frameworks exhibit reversible specific capacities of 272 mA h g−1 at 0.1 A g−1 and 121 mA h g−1 even at 10 A g−1, a high capacity retention of 93.4% at 2 A g−1 after 1000 cycles, indicating its good rate capability and very long lifespan. Sodium-ion full cells consisting of carbon frameworks anode and Na3V2(PO4)3 cathode are assembled. The full cells deliver high discharge capacity (210 mA h g−1 at 0.1 A g−1) and superior stability of 1000 cycles (0.012% capacity loss per cycle). The present paper proposes a universal approach for rational design of high-performance sodium-ion battery anode from highly aromatic precursors by molecular engineering.