In Situ Grown Hierarchical Electrospun Nanofiber Skeletons with Embedded Vanadium Nitride Nanograins for Ultra-Fast and Super-Long Cycle Life Aqueous Zn-Ion Batteries

摘要

The issues of inadequate cycle stability and energy density for aqueouszinc-ion batteries (ZIBs) can be partly addressed by controlling cathodedissolution and structural deterioration and improving electronic conductivityand reaction kinetics. Herein, vanadium nitride embedded nitrogen-dopedcarbon nanofiber (VN/N-CNFs) composites with 3D self-supported skeletonsand hierarchical structures are developed by an electrospinning technique andthermal treatments. The introduction of vanadium-based metal organicframeworks (V-MOFs) contributes to in situ hierarchical growth of whiskerlikesecondary structures and homogeneous distribution of 0D active VNnanograins into both trunk nanofibers and branched nano-whiskers. Theprotective and conductive carbon matrix derived from functional V-MOFsand electrospun nanofibers not only prevents the self-aggregation of highlyactive0D nanograins, but also provides encapsulating shells to suppressthe vanadium dissolution by controlling the direct contact with aqueouselectrolytes. Furthermore, the flexible and free-standing 3D electrospunVN/N-CNFs skeletons contribute high structural integrity for the aqueousZIBs, exhibiting an ultra-long cycle lifespan with reversible capacity of 482mAh g~(?1) after cycling at 50 A g~(?1) for 30,000 cycles and a super-high ratecapability with discharge capacity of 297 mAh g~(?1) at high rate of 100 A g~(?1). Thisresearch sheds light upon a pathway toward designing superior ZIBs.