Construction And Performance Study On Aqueous Zinc Ion Battery/hybrid Capacitor Based On VO₂（B）

Efficient storage of renewable energy is the key to a clean energy development strategy.In recent years,aqueous zinc ion energy storage systems have received a lot of attention due to their high safety,non-toxic and environment-friendly advantages.Vanadium-based compounds have become a widely used cathode material in aqueous zinc ion energy storage systems for their abundant reserve and high theoretical capacity.Nevertheless,the slow reaction kinetics,poor electrical conductivity and weak structural stability of vanadium-based materials have greatly limited the further application of aqueous zinc ion energy storage systems.To address the problems of vanadium-based materials,this paper takes vanadium dioxide（VO₂（B））as the object of study and focuses on the following:（1）VO₂（B）with different tungsten（W）doping ratios are prepared based on hydrothermal method to investigate the effects of W doping on the morphology,crystal structure and electrochemical properties of VO₂（B）.The introduced W can act as a pillar to prevent the structural collapse of VO₂（B）after ion deintercalation and improve the cycling stability of VO₂（B）electrodes.In addition,W doping can increase the intrinsic conductivity of VO₂（B）and achieve fast reaction kinetics.Compared with VO₂（B）,3%W-VO₂（B）exhibites an excellent specific discharge capacity of 326 m Ah g^-1 at 0.2 A g^-1.Even after 1000 cycles at 5 A g^-1,it still exhibits a capacity retention of91%.In situ XRD indicates that the energy storage mechanism of the 3%W-VO₂（B）electrode is Zn²⁺/H⁺co-intercalation.The aqueous zinc ion hybrid capacitors（AZIHCs）are assembled with 3%W-VO₂（B）as the cathode and activated carbon（AC）as the anode,and also demonstrate good cycling stability.It experiences 5000 cycles at 5 A g^-1 with a capacity retention close to 100%.（2）VO₂（B）with different titanium dioxide（Ti O₂）deposition cycles are prepared based on the atomic layer deposition technique,and the effects of Ti O₂ atomic layer deposition on the morphology,crystal structure and electrochemical properties of VO₂（B）are investigated.In AZIBs,VO₂（B）@Ti O₂-150 achieves a high specific discharge capacity of 310 m Ah g^-1 at 0.2 A g^-1.At the same time,it exhibits excellent rate capability of 75 m Ah g^-1 at 10 A g^-1.The AZIHCs are assembled with VO₂（B）@Ti O₂-150 as the cathode and AC as the anode,and also exhibit excellent cycling stability.The capacity retention is 89%after cycling 5000 cycles at a current density of 5A g^-1.