posted on 2023-01-10, 11:04authored byJiaxiang Chi, Hai Xu, Jiuqing Wang, Xueqing Tang, Shuang Yang, Bing Ding, Hui Dou, Xiaogang Zhang
As a promising candidate for large-scale energy storage,
aqueous
zinc-ion batteries (ZIBs) still lack cathode materials with large
capacity and high rate capability. Herein, a spherical carbon-confined
nanovanadium oxynitride with a polycrystalline feature (VNxOy/C) was synthesized
by the solvothermal reaction and following nitridation treatment.
As a cathode material for ZIBs, it is interesting that the electrochemical
performance of the VNxOy/C cathode is greatly improved after the first charging
process viain situ electrochemically
oxidative activation. The oxidized VNxOy/C delivers a greatly enhanced reversible
capacity of 556 mAh g–1 at 0.2 A g–1 compared to the first discharge capacity of 130 mAh g–1 and a high capacity of 168 mAh g–1 even at 80
A g–1. The ex situ characterizations
verify that the insertion/extraction of Zn2+ does not affect
the crystal structure of oxidized VNxOy/C to promise a stable cycle life (retain 420
mAh g–1 after 1000 cycles at 10 A g–1). The experimental analysis further elucidates that charging voltage
and H2O in the electrolyte are curial factors to activate
VNxOy/C in
that the oxygen replaces the partial nitrogen and creates abundant
vacancies, inducing a conversion from VNxOy/C to VNx–mOy+2m/C and then resulting in considerably strengthened rate performance
and improved Zn2+ storage capability. The study broadens
the horizons of fast ion transport and is exceptionally desirable
to expedite the application of high-rate ZIBs.