Boosting Zn²⁺ and NH₄⁺ Storage in Aqueous Media via In‐Situ Electrochemical Induced VS₂/VO_x Heterostructures

Abstract

Aqueous‐ion batteries have received much attention owing to the merits of high safety, low cost, and environmental friendliness. Among potential cathode candidates, transition metal sulfides drew little attention since they suffer from low capacity, low working potential, and fast capacity fading. Here, advantage is taken of the chemical instability of VS2 in aqueous electrolyte to in situ fabricate a heterostructural VS2/VOx material. Benefiting from the internal electric field at heterointerfaces, high conductivity of vanadium sulfide and high chemical stability of vanadium oxides, heterostructural VS2/VOx delivers an enhanced working potential by 0.25 V, superior rate capability with specific capacity of 156 mA h g−1 at 10 A g−1, and long‐term stability over 3000 cycles as Zn2+ storage electrode. In addition, heterostructural VS2/VOx is employed as the cathode for aqueous NH4+ ion storage with high reversible capacity over 150 mA h g−1 and long lifespan over 1000 cycles, surpassing the state‐of‐the‐art materials. VS2/VOx is proved to demonstrate a (de)intercalation process for Zn2+ storage, while a conversion reaction accompanied by insertion is responsible for nonmetal NH4+. The strong insight obtained in this study sheds light on a new methodology of exploring the potential of transition metal sulfides‐based cathode materials for aqueous ion batteries.

Enhanced Reversible Zinc Ion Intercalation in Deficient Ammonium Vanadate for High-Performance Aqueous Zinc-Ion Battery

“…After charged to 1.6 V, the V cations are oxidized, and the V 2p spectrum is similar to that of initial state, suggesting good reversible redox reactions. Figure 5 g shows the XPS spectra of O 1 s. After the first discharging process, the peaks located at around 532.5 and 533.0 eV are attributed to water molecules and OH − , respectively, indicating to the insertion of hydrated zinc ions and the formation of Zn 3 V 2 O 7 (OH) 2 ·2H 2 O [ 80 ]. After charging to 1.6 V, the H 2 O signal is retained while the OH − signal disappears, which further suggests the decomposition of Zn 3 V 2 O 7 (OH) 2 ·2H 2 O.…”

Oxygen Defects Engineering of VO2·xH2O Nanosheets via In Situ Polypyrrole Polymerization for Efficient Aqueous Zinc Ion Storage

“…[9][10][11] There is no doubt that fer reting out desirable cathode materials for AZIBs becomes the most urgent need. In the previous numerous researches, various manganese−based oxides, [12][13][14] Prussian blue analogs (PBAs) [15,16] and layered tran sition−metal dichalcogenides (TMDs) [17,18] have been deeply explored on account of their typical characteristic structures. However, vanadium−based compounds, strikingly for vanadium oxides and metal vanadates, [19][20][21][22][23] have attracted conspicuous attention for the host materials acting as cathodes of AZIBs because of the high theoretical capacity, versatile vanadium oxide frameworks, simple preparation methods and low cost.…”

Recent Advance and Modification Strategies of Transition Metal Dichalcogenides (TMDs) in Aqueous Zinc Ion Batteries

“…Yu et al [ 50 ] first used the in situ electrochemical pretreatment of VS 2 in aqueous medium and obtained VS 2 /VO x heterostructures as cathode materials for ZIB. The fluffy VO x nanosheets are uniformly grown on VS 2 , forming an interwoven porous electrode rich in VS 2 and VO x heterostructures.…”

“… ( a ) HR−TEM image and rate performance of layered VS 2 [ 45 ]; ( b ) SEM image of VS 2 grown on SS mesh and rate performance of VS 2 @SS electrode [ 46 ]; ( c ) HRTEM image and rate performance of the rGO−VS 2 composites [ 47 ]; ( d ) SEM image and rate performance of the VS 2 @VOOH−18h [ 48 ]; ( e ) HRTEM image and rate performance of VS 2 ·NH 3 electrode [ 49 ]; ( f ) TEM image and rate capability of in−situ electrochemical oxidation formed VS 2 /VO x [ 50 ]. …”