Rapid Electrochemical Activation of V₂O₃@C Cathode for High‐Performance Zinc‐Ion Batteries in Water‐in‐Salt Electrolyte

Abstract

Aqueous Zn-ion batteries (ZIBs), with the advantages of low cost, high safety, and high capacity, have great potential for application in grid energy storage and wearable flexible devices. However, their commercial application is still restricted by their inferior long-term cycling stability, Zn dendrite formation, and the decomposition of aqueous electrolyte. In this study, a Zn j Zn(CF 3 SO 3 ) 2 + LiTFSI j V 2 O 3 @C cell is constructed to address the above issues. The V 2 O 3 @C electrode can be fully oxidized into amorphous V 2 O 5 @C simultaneously with Zn 2 + and H 2 O co-insertion. The cell delivers a high specific capacity of more than 240 mAh g À 1 at 3 A g À 1 , with extraordinary coulombic efficiency and capacity retention. The excellent electrochemical performances are attributed to synergistic effects between the V 2 O 3 @C electrode and the water-in-salt electrolyte with enhanced stability and improved interface reaction kinetics. Systematic improvements of this architecture indicate much promise for application.

Recent Progress on the Performance of Zn-Ion Battery Using Various Electrolyte Salt and Solvent Concentrations

“…The WiS electrolyte exhibited a lower contact angle than diluted electrolyte (ZnSO 4 and Zn(OTf) 2 ), suggesting the WiS electrolyte greatly improved the V 2 O 3 @C cathode wettability and facilitated Zn 2+ -ion transfer kinetics (Figure 7c). 80 In addition, the redox peaks were shifted to higher potential than those for diluted electrolyte. 80 Moreover, it is evident that the highly concentrated WiS electrolyte based on 21 M LiTFSI + 0.43 M Zn(OTf) 2 , which contained almost no free water molecules, exhibited comparatively lower electrochemical performance than 6 M LiTFSI + 3 M Zn(OTf) 2 WiS electrolyte.…”

“…80 In addition, the redox peaks were shifted to higher potential than those for diluted electrolyte. 80 Moreover, it is evident that the highly concentrated WiS electrolyte based on 21 M LiTFSI + 0.43 M Zn(OTf) 2 , which contained almost no free water molecules, exhibited comparatively lower electrochemical performance than 6 M LiTFSI + 3 M Zn(OTf) 2 WiS electrolyte. This result suggested that an appropriate amount of free water molecules is required in electrolyte to exhibit high electrochemical performance.…”

“…This result suggested that an appropriate amount of free water molecules is required in electrolyte to exhibit high electrochemical performance. 80 The reductive decomposition of salt anion formed an SEI on the electrode, facilitated smooth extraction/ insertion of Zn2+ ions, reduced the tendency of cathode dissolution into the electrolyte. 80 The ESW and cycling stability of the Zn//V 2 O 5 ZiB device improved to a larger extent using 21 M LiTFSI + 1 M Zn(OTf) 2 mixed electrolyte.…”

“…80 The reductive decomposition of salt anion formed an SEI on the electrode, facilitated smooth extraction/ insertion of Zn2+ ions, reduced the tendency of cathode dissolution into the electrolyte. 80 The ESW and cycling stability of the Zn//V 2 O 5 ZiB device improved to a larger extent using 21 M LiTFSI + 1 M Zn(OTf) 2 mixed electrolyte. 81 Two pairs of oxidation/reduction peaks (charge (∼1.06 and ∼1.23 V) and discharge (∼0.90 and ∼1.10 V)) were observed during the GCD process in mixed electrolyte which are ascribed to the dual Li + -/Zn 2+ -ion insertion/ extraction.…”

Advances on Defect Engineering of Vanadium‐Based Compounds for High‐Energy Aqueous Zinc–Ion Batteries

“…Among them, V 2 O 5 with various morphology and their composites has been widely explored as cathode for ZIBs. [28][29][30][31] Both orthorhombic V 2 O 5 (α-V 2 O 5 ) and bilayered V 2 O 5 (V 2 O 5 nH 2 O) have typical layered structures (Figure 3a,b) with adjacent layers combined by Van der Waals force. [32,33] α-V 2 O 5 possesses a layer spacing of 5.8 Å, which is large enough for storing Zn 2+ and V 2 O 5 nH 2 O usually has larger layer spacing with crystal water in the interlayer.…”