Self‐Transformation Strategy Toward Vanadium Dioxide Cathode For Advanced Aqueous Zinc Batteries

Abstract

In the lithium‐dominated era, rechargeable Zn batteries are emerging as a competitive alternative. However, the sluggish kinetics of ion diffusion and structural destruction of cathode materials have thus far hampered the realization of future large‐scale energy storage. Herein, an in situ self‐transformation approach is reported to electrochemically boost the activity of a high‐temperature, argon‐treated VO2 (AVO) microsphere for effective Zn ion storage. The presynthesized AVO with hierarchical structure and high crystallinity allows efficient electrochemical oxidation and water insertion to induce self‐phase transformation into V2O5·nH2O within the first charging process, which leads to rich active sites and fast electrochemical kinetics. Using AVO cathode, an outstanding discharge capacity of 446 mAh g−1 at 0.1 A g−1, high rate capability of 323 mAh g−1 at 10 A g−1 and excellent cycling stability for 4000 cycles at 20 A g−1 with high capacity retention are demonstrated. Importantly, such zinc‐ion batteries with phase self‐transition can also perform well at high‐loading, sub‐zero temperature, or pouch cell conditions for practical application. This work not only paves a new route to design in situ self‐transformation in energy storage devices, but also broadens the horizons of aqueous zinc‐supplied cathodes

Structural Engineering of Vanadium Oxide Cathodes by Mn2+ Preintercalation for High-Performance Aqueous Zinc-Ion Batteries

“…47 Comparison with pure VO 2 showed that the peaks of MnVO had shifted, indicating that the introduction of Mn 2+ as a pillar into the tunnel structure of VO 2 altered the main skeleton structure. 48 Figure 3b shows the electron paramagnetic resonance (EPR) spectra of MnVO and VO 2 , providing direct evidence for anionic vacancies.…”

“…The peaks at 505 and 683 cm –1 were assigned to the coordination of vanadium atoms with two (V 2 –O) and three (V 3 –O) oxygen atoms, respectively, while the peak at 983 cm –1 corresponded to the stretching vibration of vanadium and terminal oxygen . Comparison with pure VO 2 showed that the peaks of MnVO had shifted, indicating that the introduction of Mn 2+ as a pillar into the tunnel structure of VO 2 altered the main skeleton structure Figure b shows the electron paramagnetic resonance (EPR) spectra of MnVO and VO 2 , providing direct evidence for anionic vacancies.…”

Current Challenges and Advanced Design Strategy of Vanadium Dioxide Cathode for Low‐Cost Aqueous Zinc Metal Battery

“…And, this new phase acts as the subsequent host material to store charge ion. Recently, Deng et al [ 17 ] found that the argon‐treated VO 2 can induce self‐phase transformation into V 2 O 5 ·nH 2 O as new cathode material at the initial charge process by the electrochemical oxidation and water insertion ( Figure a). This resulting V 2 O 5 ·nH 2 O has higher theoretical specific capacity and a self‐adaptive layer transformation structure connected by van der Waals forces for the enhanced significantly specific capacity and cycle stability.…”

“…Similarly, Deng et al, Chen et al, and Li et al also found this phase transmission from the initial VO 2 into V 2 O 5 •nH 2 O delivers outstanding performance. [11,17,18] Moreover, this phase transition product may also be zinc vanadate compounds (such as Zn 3 (OH) 2 V 2 O 7 •2H 2 O, Zn 2 V 2 O 7 and Zn 0.25 V 2 O 5 •nH 2 O, Figure 3b-d) as cathode material to storage charge ions for AZMB with superior performance based on the VO 2 and inserted zinc ions reacting with the electrolyte during the initial cycling process. [19] However, the detailed transformation mechanism of this phase transition reaction needs further detailed discussion, such as the transition condition.…”

“…Moreover, zinc ions usually exist in the form of hydrated [Zn(H 2 O) 6 ] 2þ ions with a higher radius (0.55 nm) than Zn 2þ ion (0.076 nm) in aqueous electrolyte, which will greatly Reproduced with permission. [17] Copyright 2023, Wiley-VCH. b) Zn 2 V 2 O 7 .…”