Tailored N-doped porous carbon nanocomposites through MOF self-assembling for Li/Na ion batteries

Presently, carbon-based anodes for energy storage, such as graphite for lithium-ion batteries (LlBs) and hard carbon for sodium-ion batteries (SlBs), have low capacity and poor rate properties. However, the capacity and rate capability of these anodes can be improved via morphological control, doping and using nanostructures. In this report, a series of self-assembled N-doped porous carbon nanocomposites (NPCNs) were prepared via pyrolysis of metal-organic frameworks (MOFs)-ZIF-8/carbon nanocomposites grown on various carbon frameworks (1D CNT and/or 2D rGO). It was found that the NPC-CNT@G electrode significantly exhibits superior performance for lithium/sodium storage among the other NPCNs. NPC-CNT@G electrode delivers high initial reversible capacities (986 mAh g^-1 at 0.1 A g^-1 in LIBs; 315 mAh g^-1 at 0.05 A g^-1 in SIBs), excellent rate properties (443 mAh g^-1 at 5 A g^-1 in LIBs; 174 mAh g^-1 at 1 A g^-1 in SIBs) and durable cycle life (99% capacity retention after 2000 cycles at 5 A g^-1 in LIBs, 80% capacity retention after 300 cycle at 1 A g^-1 in SIBs). This 'carbon-on-carbon' approach described herein can be applied to make other interesting structures for high performance battery materials.