In-situ growth of hierarchical N-doped CNTs/Ni Foam scaffold for dendrite-free lithium metal anode

Abstract

Practical application of lithium metal (Li) anodes is impeded by Li dendrites generated by nonuniform deposition, which always leads to severe safety hazards. Herein, a stable hierarchical scaffold is rationally designed for dendrite-free lithium metal anode (LMA). The hierarchical scaffold consists of in-situ grown N-doped carbon nanotubes on the porous Ni foam (NCNT/NF), in which the interconnected NCNTs form the secondary structure and render numerous nucleation sites for uniform Li deposition. When applied as the Li metal anode, the NCNT/NF exhibits dendrite-free morphology without serial cracks and dead Li deposition whether it is treated by direct Li deposition or by infusing molten Li into the well-designed lithiophilic structure. Particularly, the hierarchical NCNT/NF scaffold shows low overpotential and high coulombic efficiency (average 98.2% over 200 cycles at 1 ​mA ​cm−2) during Li stripping/plating process. Furthermore, an ultralong life span over 400 ​h ​at 3 ​mA ​cm−2 with high areal capacity of 3 ​mA ​h cm−2 and stable full cell performance coupled with LiFePO4 (capacity retention of 94% after 400 cycles at 2C) can be achieved by NCNT/NF/Li composite anode. This is attributed to the rational design of NCNT/NF scaffold, which combines both the merits of hierarchical framework and excellent Li affinity from N-rich species (pyridinic N and pyrrolic N).