Sodium Storage in Coal/Biomass‐Derived Carbon/Carbon 3D Networks

Abstract Coal plays an important role in human industrialization as a fossil fuel and has attracted attention recently as an ideal carbon precursor for next‐generation sodium‐ion‐battery anode materials. In this work, nitrogen‐doped three‐dimensional (3D) coal‐based carbon materials were constructed, in which coal‐based graphite microcrystals (CGCs) supply plentiful active sites for Na absorption, and chitosan‐derived 3D carbon networks accelerate the electron transfer. The materials exhibited a Na storage capacity of 283.3 mAh g −1 at 0.1 C, with capacitance retention of 94.3 % after the fifth cycle. Moreover, 170 mAh g −1 can be achieved at 2 C after 3000 cycles, which is twice that of pure CGCs. The materials are low cost and exhibit a good capacity, showing that they could be used in practical applications for sodium‐ion‐battery anodes.