Carbonaceous materials are the most promising candidates as the anode for sodium-ion batteries(SIBs),however,they still suffer from low electric conductivity and sluggish sodium ion(Na+)reaction kinetics.Appropriate composition modulation using heteroatoms doping and structure optimization is highly desired.A basic empirical understanding of the structure-capacity relationship is also urgent in tackling the above problems.Herein,multi-functional nitrogen(N)doped carbon micro-rods with enlarged inter-layer spacing are synthesized and investigated as the anode in SIBs,showing an ultra-stable capacity of 161.5 mAh g-1 at 2 A g-1 for over 5000 cycles.Experimental investigations and first-principle calculations indicate that the enlarged interlayer spacing can facilitate Na+intercalation and N doping can guarantee the high electric conductivity and favorable electrochemical active sites.Additionally,pyridinic N is the-oretically proved to be more effective to enhance Na+adsorption than pyrrolic N due to the lower adsorp-tion energy and stronger binding energy with Na+.Full SIBs show a high capacity and cyclability,making the biomass-derived carbon micro-rods to be a promising anode for practical SIBs applications.