Intrinsic effects of precursor functional groups on the Na storage performance in carbon anodes

The oxygen-containing functional groups in disordered carbon anodes have been widely reported to influence the Na storage performance. However, the effect of original oxygen-containing groups in the precursors on the final structures and electrochemical performance is rarely studied. Herein, we used the anthraquinone derivatives with different oxygen-containing functional groups as precursors to make the disordered carbon anodes for Na-ion batteries (NIBs). Through comprehensive structural and electrochemical analyses, we found that the different types of functional groups in carbon precursors directly affect the cross-linking process during carbonization. The original precursors containing enough inter-chain oxygen or oxygen-containing functional groups with unsaturated bonds unattached to the ring are beneficial for the oxygen atoms to remain or cross-link in structure to result in more C–O–C group, forming nanovoids and disordered structure, which then determine the high performance of the carbon anodes in NIBs. This work highlights the importance of the type/content of functional groups in precursor and provides guidance for the future design of carbon anodes in NIBs from the perspective of precursor selection.