Porous MOFs-Zinc Cobaltite/Carbon Composite Nanofibers for High Lithium Storage

The zinc cobaltite possesses merit of high theoretical specific capacity. However, issues of low conductivity and volume expansion during lithiation and delithiation lead to severe capacity fading. In this work, a porous zinc cobaltite/carbon composite nanofiber is synthesized with a metal-organic frameworks (MOFs) structure through electrospinning, in situ growth, and hydrothermal reaction. The obtained zinc cobaltite/carbon composite nanofibers have an improved specific surface area (90.61 m2 g-1), enabling excellent electrochemical performance as anode materials in Li-ion batteries. Briefly, a high initial discharge capacity of 2468 mAh g-1 and reversible capacity of 2008 mAh g-1 after the 200 cycles, and an outstanding rate capability of 937 mAh g-1 at 2 A g-1 are achieved. The capacity fading of MOFs-zinc cobaltite/carbon composite nanofibers is significantly improved, which can be attributed to the following reasons: i) the MOFs structure effectively relieve the strain stemming from volume expansion of transition metal; ii) the abundance of mesoporous structure facilitates the electron transport for Li+ diffusion rate by shortening the Li-ion diffusion path during lithiation/delithiation process; iii) the carbon nanofibers with excellent conductivity enable efficient conduction efficiency of lithium ions and electrons. The proposed strategy offers a new perspective to prepare high-performance electrode for lithium-ion batteries.