Nitrogen-doped carbon encapsulated zinc vanadate polyhedron engineered from a metal-organic framework as a stable anode for alkali ion batteries.

In this work, we fabricated vanadium/zinc metal-organic frameworks (V/Zn-MOFs) derived from self-assembled metal organic frameworks, to further disperse ultrasmall ZnVO nanoparticles and encapsulate them in a nitrogen-doped nanocarbon network (ZVO/NC) under in situ pyrolysis. When employed as an anode for lithium-ion batteries, ZVO/NC delivers a high reversible capacity (807 mAh g at 0.5 A g) and excellent rate performance (372 mAh g at 8.0 A g). Meanwhile, when used in sodium-ion batteries, it exhibits long-term cycling stability (7000 cycles with 145 mAh g at 2.0 A g). Additionally, when employed in potassium-ion batteries, it also shows outstanding electrochemical performance with reversible capacities of 264 mAh g at 0.1 A g and 140 mAh g at 0.5 A g for 1000 cycles. The mechanism by which the pseudocapacitive behaviour of ZVO/NC enhances battery performance under a suitable electrolyte was probed, which offers useful enlightenment for the potential development of anodes of alkali-ion batteries. The performance of ZnVO as an anode for SIBs/PIBs was investigated for the first time. This work provides a new horizon in the design ZVO/NC as a promising anode material owing to the intrinsically synergic effects of mixed metal species and the multiple valence states of V.