Rechargeable aqueous zinc-ion batteries are highly desirable for grid-scale applications due to their low cost and high safety; however, the poor cycling stability hinders their widespread application. Herein, a highly durable zinc-ion battery system with a NaVO·1.63HO nanowire cathode and an aqueous Zn(CFSO) electrolyte has been developed. The NaVO·1.63HO nanowires deliver a high specific capacity of 352 mAh g at 50 mA g and exhibit a capacity retention of 90% over 6000 cycles at 5000 mA g, which represents the best cycling performance compared with all previous reports. In contrast, the NaVO nanowires maintain only 17% of the initial capacity after 4000 cycles at 5000 mA g. A single-nanowire-based zinc-ion battery is assembled, which reveals the intrinsic Zn storage mechanism at nanoscale. The remarkable electrochemical performance especially the long-term cycling stability makes NaVO·1.63HO a promising cathode for a low-cost and safe aqueous zinc-ion battery.

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Na 3 V 2 (PO 4 ) 3 represents a well-known NASICON-structured SIB cathode. It possesses a theoretical capacity of 117 mAh g −1 with a discharge plateau at ≈3.4 V.

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further development. [2] Hence, exploring novel approaches to achieve more efficient energy storage is highly demanded. Recently, aqueous batteries are attracting unprecedented attention particularly owing to their high safety, high ion conductivity, low cost, and environmental friendliness. [3] To date, numerous aqueous batteries based on Li + , Na + , K + , Mg 2+ , Ca 2+ , Zn 2+ , Al 3+ , Fe 3+ , and/or mixed metal ions as charge carriers have been reported, [4] which find potential applications in fields such as grid-scale energy storage, wearable devices, and etc. [5] Among them, as a promising candidate, the rechargeable aqueous Zn-based batteries (AZBs) including Zn-ion batteries (mild electrolyte), [6] Zn-Co/Ag/ Ni alkaline batteries [7] and Zn-air batteries in alkaline electrolyte [8] have been extensively studied due to their unparalleled advantages of Zn anode. In general, metal Zn has the features of high theoretical capacity (820 mAh g −1 ), high electrical conductivity, nontoxicity, easy processing, and suitable redox potential (−0.76 V vs standard hydrogen electrode). [9] However, most of AZBs reported so far have encountered the same challenges, which are the narrow voltage window, unsatisfactory capacity, and poor cycling performance. [10] For example, all Zn-ion batteries operated in mild electrolyte including Zn//V-based, Zn//Mn-based, and Zn//Prussian blue analogs-based hold a narrow voltage window of 0.3-1.6, 0.9-1.8, and 0.2-1.8 V, respectively. [11] Even though AZBs in alkaline electrolyte display a higher voltage than that achieved in mild medium, their voltage windows are still only about 1.2-1.9 V. [12] Meanwhile, the alkaline electrolytes show stronger corrosion than mild neutral electrolytes, which greatly limit their wide applications. Moreover, the unstable cycling performance in AZBs due to the Zn dendrites and side reaction on the surface of Zn anode is also unsatisfactory. [10] To date, the electrolyte optimization or structural design are the common ways to suppress the growth of Zn dendrite and improve the cycling stability. For example, Chen and co-workers reported that aqueous electrolyte Zn(CF 3 SO 3 ) 2 can suppress the formation of detrimental dendrites in AZBs owing to the better reversibility and faster kinetics of Zn deposition/dissolution than that in ZnSO 4 electrolyte. [13] However, Zn(CF 3 SO 3 ) 2 is too expensive (≈$ 8.1 g −1 , prices from Sigma-Aldrich) to be applied With the increasing energy crisis and environmental pollution, rechargeable aqueous Zn-based batteries (AZBs) are receiving unprecedented attention due to their list of merits, such as low cost, high safety, and nontoxicity. However, the limited voltage window, Zn dendrites, and relatively low specific capacity are still great challenges. In this work, a new reaction mechanism of reversible Mn 2+ ion oxidation deposition is introduced to AZBs. The assembled Mn 2+ /Zn 2+ hybrid battery (Mn 2+ /Zn 2+ HB) based on a hybrid storage mechanism including Mn 2+ ion deposition, Zn 2+ ion insertion, and co...