Oxygen-deficient NH4V4O10 cathode with Ag quantum dots and interlayer Ag+ towards high-performance aqueous zinc ion batteries

Herein, oxygen-deficient NH 4 V 4 O 10 micro-flowers with loaded Ag quantum dots and pre-intercalated Ag + (NVO-Ag) for aqueous zinc ion battery (AZIB) cathode materials were successfully synthesized by a one-step hydrothermal method. The reversible redox reaction between Ag + and Ag quantum dots, and the abundant Zn 2+ storage sites from oxygen vacancies provided capacity contributions for NVO-Ag. Meanwhile, the loaded Ag quantum dots, pre-intercalated Ag + and introduced oxygen vacancies synergistically optimized the electronic structure and distribution of NVO-Ag, promoting the transport of electrons in NVO-Ag. The pre-intercalated Ag + could also replace the NH 4 + in the interlayer of NH 4 V 4 O 10 , weakening the repulsion between the interlayer NH 4 + and Zn 2+ , which achieved rapid Zn 2+ diffusion kinetics. Moreover, the abundant oxygen vacancies in NVO-Ag could alleviate the strong electrostatic interaction between Zn 2+ and V-O framework, boosting the transmission of Zn 2+ in NVO-Ag. Finally, the structural stability of NH 4 V 4 O 10 micro-flowers was improved due to the high bonding strength between Ag + and V-O layers. Benefiting from the above effects, NVO-Ag-100 achieved excellent capacity performance (387.2 mAh g −1 at 0.5 A g −1 ), rate performance (178.9 mAh g −1 at 12 A g −1 ) and cycle stability (91.7 % capacity retention after 1700 cycles at 8 A g −1 ). This work provided effective ideas to achieve high-performance AZIB cathode materials.