Adjusting oxygen vacancy of VO2.xH(2)O nanoarray architectures for efficient NH4+ storage

Aqueous rechargeable batteries are the promising energy storge technology due to their safety, low cost, and environmental friendliness. Ammonium ion (NH4+) is an ideal charge carrier for such batteries because of its small hydration radius and low molar mass. In this study, VO2.xH(2)O with rich oxygen defects (d-HVO) is designed and synthesized, and it exhibits unique nanoarray structure and good electrochemical performances for NH4+ storge. Experimental and calculation results indicate that oxygen defects in d-HVO can enhance the conductivity and diffusion rate of NH4+, leading to improved electrochemical performances. The most significant improvement is observed in d-HVO with 2 mmol thiourea (d-HVO-2) (220 mAh.g(-1) at 0.1 A.g(-1)), which has a moderate defect content. A full cell is assembled using d-HVO-2 as the anode and polyaniline (PANI) as the cathode, which shows excellent cycling stability with a capacity retention rate of 80% after 1000 cycles and outstanding power density up to 4540 W.kg(-1). Moreover, the flexible d-HVO-2 & PAR;PANI battery, based on quasi-solid electrolyte, shows excellent flexibility under different bending conditions. This study provides a new approach for designing and developing high-performance NH4+ storage electrode materials.

Automated summary

In this study, oxygen-deficient VO2.xH(2)O nanoarrays (d-HVO) are designed and synthesized as anode materials for NH4+ rechargeable batteries. The oxygen defects in d-HVO enhance the conductivity and diffusion rate of NH4+, resulting in improved electrochemical performances. The d-HVO-2 with 2 mmol thiourea exhibits the best performance, with a capacity of 220 mAh.g(-1) at 0.1 A.g(-1). A full cell assembled with d-HVO-2 and polyaniline (PANI) cathode shows excellent cycling stability and high power density, and the flexible d-HVO-2 & PAR;PANI battery demonstrates outstanding flexibility under different bending conditions.