Dual-engineering of ammonium vanadate for enhanced aqueous and quasi-solid-state zinc ion batteries

De-Ammonium Ba0.18V2O4.95/NH4V4O10 Film Electrodes as High-Performance Cathode Materials for Magnesium-Ion Batteries

“…Electrochemical impedance spectroscopy (EIS) tests further confirm the fast response kinetics of the film electrode in the range of 100 kHz to 0.1 Hz. As shown in Figure , R s is the solution resistance, and the semicircle in the high and medium frequency regions indicates the charge transfer resistance ( R ct ) at the interface between the electrode and the electrolyte, while the low-frequency diagonal line after the semicircle corresponds to the diffusion impedance ( Z w ). ,, The semicircular diameters obtained for the film electrode BaVO-400 in both the high and medium frequency regions are smaller than BaVO-450, indicating its good electrical conductivity. In detail, we measured the EIS of the film electrodes under different discharge cycles, and the data are shown in Table below.…”

“…In addition, NH 4 + has a large ionic radius (143 pm) and small molecular weight (18 g mol –1 ), which can result in large layer spacing and mass advantages . NH 4 + can also form N–H···O hydrogen bonds with the [VO n ] layers to ensure the stability of the bilayer structure and promote the reversible reaction of Mg 2+ at the electrode. , However, the presence of too much large volume of NH 4 + between vanadium–oxygen layers can lead to blocked Mg 2+ insertion and limit the capacity . Therefore, de-ammonium becomes an effective means of maximizing the capacity of ammonium vanadate.…”

“…28,35 However, the presence of too much large volume of NH 4 + between vanadium−oxygen layers can lead to blocked Mg 2+ insertion and limit the capacity. 36 Therefore, de-ammonium becomes an effective means of maximizing the capacity of ammonium vanadate. Combining the favorable role played by Ba 2+ and NH 4 + between vanadium−oxygen layers and the effective method to achieve de-ammonium can provide a good idea to develop vanadate materials as electrodes for MIBs.…”

Improved strategies for ammonium vanadate-based zinc ion batteries

“…Zheng et al proposed a dual engineering approach to prepare nanoribbons of NH 4 V 4 O 10 (NVO) using a combination of elevated temperature treatment for the partial elimination of ammonium cations and the addition of oxygen vacancies to investigate their zinc storage properties. 39 Results from both experimental studies and theoretical calculations demonstrate that the method increases the intercalation space of Zn 2+ ions, weakens the electrostatic force between the V–O layer and Zn 2+ , and lowers the energy threshold for Zn 2+ diffusion. Accordingly, the specific capacity of the NVO-300, which has dual characteristics, was augmented from 304 mA h g −1 to 355 mA h g −1 , leading to a more than 300% increase in its rate capability compared with the original NVO.…”

“…However, two key issues need to be addressed in the practical application of ammonium vanadate materials. 39 The first one is that excess ammonium ions occupy the interlayer, leading to a restricted insertion of zinc ions; thus, the capacity of ammonium vanadate is limited. The second one is that the strong electrostatic interaction between Zn 2+ and defect-free V–O bonds inhibits the subsequent (de)intercalation behavior, leading to a decrease in performance.…”