Simultaneous Incorporation of V and Mn Element into Polyanionic NASICON for High Energy‐Density and Long‐Lifespan Zn‐Ion Storage

Abstract

batteries have attracted great attention. [2,3] Among them, aqueous Zn-ion batteries (AZIBs) shows apparent merits of abundant zinc sources, low development cost, high security, and environmental friendliness. More importantly, the chemical stability of metal zinc in a water-oxygen environment is much superior than other alkali metals and polyvalent metals, thus in favor of the design of aqueous batteries. [4,5] However, the revolution of AZIBs is still at its early stage and far from the practical application because of the lack of suitable cathode materials. The relatively high redox potential of ≈−0.76 V (vs NHE) of Zn 2+ /Zn generally calls for high-voltage cathodes to construct an aqueous battery with satisfying energy density. [6] Recently, polyanionic compounds consisting of alternately linked [XO 4 ] (X = P, S, Si, etc.) tetrahedron and [MO 6 ] (M = V, Mn, Fe, Co, Cr, etc.) octahedron have been developed as very promising candidates for AZIBs cathode. Profiting from the inductive effect on the MO bond and the binding effect on oxygen atoms originating from the presence of [XO 4 ], polyanionic compounds generally combine the disadvantages of a high discharged plateau and excellent thermal stability. [7][8][9] Typically, a series of V-based phosphate based polyanionic compounds have been reported for the construction of ZIBs cathode materials such as layered hydrated VOPO 4 and NASICON-typed Na 3 V 2 PO 4 . [10,11] For instance, Huang et al. revealed that NASICON-typed Na 3 V 2 (PO 4 ) 3 displays a specific capacity of ≈100 mAh g −1 and a satisfying plateau of ≈1.1 V when served as a ZIBs cathode. [11] Our previous work also revealed layered hydrated VOPO 4 .2H 2 O as high voltage cathode materials originated from the aforementioned inductive effect. [12][13][14] Nevertheless, in spite of the high voltage plateau and decent cyclability, relative low specific capacity (generally < 150 mAh g −1 ) of V-based phosphate based polyanionic compounds is still a huge obstacle for the realization of high energy density cathode. [12,15,16] It is known that V and Mn are two important active metal elements in most of AZIBs cathode materials. This inspired us to consider whether one can incorporate V and Mn elements simultaneously into polyanionic compounds hosts to Aqueous Zn-ion battery (AZIB) has attracted huge attention due to its distinct advantages such as abundant zinc sources, low development cost, high security, and environmental friendliness compared to traditional commercialized batteries. Developing novel cathode materials with high energy density and long lifespan is very important for the practical application of AZIB in the coming years. Herein, V and Mn elements are simultaneously incorporated into the NASICON host to make use of the electrochemical redox reaction in both V and Mn transition metal elements for aqueous Zn-ion storage. A significant increase in both capacity and working voltage has been observed after Mn doping into Na 3 V 2 (PO 4 ) 3 to form Na 4 VMn(PO 4 ) 3 . Taking advantage of the me...

Texturing Crystal Plane of Zinc Metal via Cleavage Fracture for a Dendrite-Free Zinc Anode

“…Zn anodes are widely used in aqueous zinc-ion batteries (ZIBs) for their distinct advantages: (1) zinc metal possesses an ultrahigh theoretical volumetric and gravimetric capacity of 5855 mA h cm –3 and 820 mA h g –1 , respectively; − (2) Zn has good compatibility with neutral or weakly acidic aqueous solution; − and (3) commercial Zn foil is easily available and inexpensive. , However, the dendrite problem seriously hinders the development of Zn metal anodes in aqueous ZIBs. − Young’s modulus of Zn is much higher than that of Li, indicating that zinc dendrites are more likely to penetrate the separator and cause a short circuit of the battery . Furthermore, the shaggy dendrite is loosely connected to the Zn substrate, and the charges on the electrode surface tend to accumulate at the dendritic root, which may cause the dendrite detachment and the formation of “dead Zn,” further leading to the decrease in Coulombic efficiency (CE). , Therefore, a lot of research work has been put into inhibiting the formation and growth of zinc dendrite, such as zinc surface coating, − current collector optimizing, − alloying, and so on. − Although these modification strategies improve the cycling performance of the Zn anode to a certain extent, they sacrifice some advantages of the zinc metal anode, such as good electrical conductivity, fast interfacial reaction kinetics, or high volumetric capacity.…”

Na+-Activation Engineering in the Na3V2(PO4)3 Cathode with Boosting Kinetics for Fast-Charging Na-Ion Batteries

“…Na 1s spectra plotted in Figure h show three characteristic peaks located at 1070.5, 1071.4, and 1072.3 eV, representing the Na + ions with varied bonding properties originating from Na2 sites (18e), V sites (12c), and Na1 sites (6b), respectively. In contrast to the pure NVP, it displays an extra Na-related chemical interaction in the high binding energy region, confirming the valid substitution of V with Na. , In the case of V 2p high-resolution XPS spectra (Figure i), the bands located at 524.2 and 517.2 eV can be assigned to the trivalent V in the NVP-Na2.5% sample. These results illustrate that the introduced Na + ions are lodged at the V site and Na2 site, and a similar phenomenon was also reported in Mg-doped NVP materials …”

“…The corresponding CV curves and pseudocapacitance proportion of NVP and NVP-Na2.5% with varied scanning rates are shown in Figure S12. As seen, the pseudocapacitive proportions of NVP-Na2.5% are 82, 85, 87, 89, and 91% at scanning rates of 0.2, 0.4, 0.6, 0.8, and 1.0 mV s −1 , respectively, larger than that of the pure NVP sample (52,59,63,68, and 71%, respectively), as seen in Figure 4d,g. It can be observed that the pseudocapacitive contribution gradually increases as the scanning rate increases, revealing the prominent surface reactions at high current rates.…”

“…In contrast to the pure NVP, it displays an extra Na-related chemical interaction in the high binding energy region, confirming the valid substitution of V with Na. 52,53 In the case of V 2p high-resolution XPS spectra (Figure 1i), the bands located at 524.2 and 517.2 eV can be assigned to the trivalent V in the NVP-Na2.5% sample. These results illustrate that the introduced Na + ions are lodged at the V site and Na2 site, 54 and a similar phenomenon was also reported in Mg-doped NVP materials.…”

In Situ Induced Coordination between a “Desiccant” Interphase and Oxygen‐Deficient Navajoite towards Highly Efficient Zinc Ion Storage

“…Compared to the overwhelming H 2 O and OH − signals assigned to ZVO at fully discharged HVO d electrode (Figure 6e), GP-HVO d shows less variation of H 2 O peak during cycling, further verifying the significance of GP to retain the interfacial stability. The V 2p spectra from GP-HVO d (Figure S22a, Supporting Information) show that V 5+ cations are partially reduced to V 4+ and V 3+ in discharge, which is highly reversible when charged back to 1.6 V. [34] Correspondingly, the intensity variation of Zn 2p characteristic peaks at 1045.4 and 1022.2 eV proves the high reversibility of Zn 2+ intercalation/deintercalation (Figure S22b, Supporting Information). [35] The uniform distribution of V, O, and Zn elements over the HVO d bulk phase in discharged GP-HVO d electrode also verifies the successful Zn 2+ intercalation (Figure 6f ).…”