Enabling Multi-electron Reactions in NASICON Positive Electrodes for Aqueous Zinc-Metal Batteries

Abstract

Sodium superionic conductor (NASICON)-structured compounds with a robust polyanionic framework, e.g., Na 3 V 2 (PO 4 ) 3 , have been considered as promising cathode candidates for rechargeable batteries due to their open 3D structure and high thermal stability. However, their practical implementation in aqueous batteries is hindered by their structural instability during the charge/discharge process. Herein, Na 3 V 2-x Cr x (PO 4 ) 3 is investigated as a cathode material for aqueous zinc-metal batteries. It is identified that the Cr substitution has a significant effect on improving its rate capability and cycling stability. As a result, the optimal Na 3 V 1.5 Cr 0.5 (PO 4 ) 3 electrode delivers an ultra-stable cycling performance (68% capacity retention after 10,000 cycles at 1000 mA g −1 ). A two-electron reaction mechanism between V 4+ /V 3+ and V 5+ /V 4+ redox couples has been revealed during the electrochemical process for Zn-ion storage. This work verifies the feasibility of multi-electron reactions in NASICON-type cathodes for aqueous zinc batteries and sheds light on designing advanced cathode materials for other aqueous batteries.

Unravelling the effect of benzoquinone intercalators on the aqueous zinc-ion storage performance toward a vanadium pentoxide cathode

“…When it returns to the charged state, the V 3+ peaks vanish and the V 5+ /V 4+ ratio reverts to 73%/27%. 45 This phenomenon proves the multi-electron transfer based on the V valence state in the redox reaction of the V 2 O 5 -BQ4Br cathode, consistent with CV curves showing two pairs of redox peaks. In the high-resolution O 1s spectrum of V 2 O 5 -BQ4Br (Fig.…”

Cation and Anion Modulation Strategies toward Ideal Zinc Artificial Interface

“…The anions that directly present in zinc salts, such as OTF − , contribute to the generation of a derived artificial SEI layer on the electrode surface. For example, the acetate anions (Ac − ) in the methylammonium acetate (MAAC) additive can participate in and reconstruct the primary solvation sheath of Zn 2+ , resulting in an anion‐enriched structure for reducing water activity and promoting the anion‐derived artificial SEI [64] . In Figure 7c, the OTF − and Ac − anions are preferentially adsorbed on the Zn surface, and the OTF − anions can be electroreduced during cycling, constructing a hybrid SEI.…”

Ethylene Glycol Intercalation Engineered Interplanar Spacing and Redox Activity of Ammonium Vanadate Nanoflowers as a High-Performance Cathode for Aqueous Zinc–Ion Batteries

“…23,24 Among these materials, layered vanadium-based compounds have been widely regarded as promising cathodes for AZIBs because of their high theoretical capacity and unique multielectron redox reaction based on the V element. 25,26 However, the narrow layer spacing of vanadium-based compounds generally leads to slow zinc ion transport. A number of investigations have focused on modulating the interlayer spacing of vanadiumbased materials using interlayer chemistry.…”

“…In recent years, most research on rechargeable cathode materials of AZIBs have focused on manganese-based compounds, ,− vanadium-based compounds, − Prussian blue analogues, , and polyanionic compounds. , Among these materials, layered vanadium-based compounds have been widely regarded as promising cathodes for AZIBs because of their high theoretical capacity and unique multielectron redox reaction based on the V element. , However, the narrow layer spacing of vanadium-based compounds generally leads to slow zinc ion transport. A number of investigations have focused on modulating the interlayer spacing of vanadium-based materials using interlayer chemistry. ,, It is found that structured water and pillared ions are essential to improve the ion diffusion kinetics of vanadium-based compounds and accelerate charge transfer, so a series of cationic preinserted vanadium oxides have been developed as cathode materials for AZIBs. − Nevertheless, the introduction of heavy metal ions into the host structure of layered V-based materials may greatly reduce their theoretical capacity .…”