Zn2+-storage mechanism in V6O13 with nanosheets for high-capacity and long-life aqueous zinc-metal batteries.

V6O13 with a nanosheet structure was employed as a cathode material for aqueous zinc metal batteries. V6O13 delivered a high specific capacity of 425 mA h g-1, outstanding rate performance and durable cycling with high capacity retention of 86% after 3000 cycles. Moreover, in situ X-ray diffractometer (XRD), ex situ X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) were employed to ascertain the reaction mechanism of Zn2+ storage.

Quicker and More Zn2+ Storage Predominantly from the Interface.

Aqueous zinc-ion batteries are highly desirable for large-scale energy storage because of their low cost and high-level safety. However, achieving high energy and high power densities simultaneously is challenging. Herein, a VOx sub-nanometer cluster/reduced graphene oxide (rGO) cathode material composed of interfacial VOC bonds is artificially constructed. Therein, a new mechanism is revealed, where Zn2+ ions are predominantly stored at the interface between VOx and rGO, which causes anomalous valence changes compared to conventional mechanisms and exploits the storage ability of non-energy-storing active yet highly conductive rGO. Further, this interface-dominated storage triggers decoupled transport of electrons/Zn2+ ions, and the reversible destruction/reconstruction allows the interface to store more ions than the bulk. Finally, an ultrahigh rate capability (174.4 mAh g-1 at 100 A g-1 , i.e., capacity retention of 39.4% for a 1000-fold increase in current density) and a high capacity (443 mAh g-1 at 100 mA g-1 , exceeding the theoretical capacities of each interfacial component) are achieved. Such interface-dominated storage is an exciting way to build high-energy- and high-power-density devices.

Electrochemical activation induced multi-valence variation of (NH4)2V4O9 as a high-performance cathode material for zinc-ion batteries.

In this paper, we found that (NH4)2V4O9 undergoes an electrochemical activation process in the first charging process at ∼1.4 V (vs. Zn2+/Zn), leading to a significant improvement of capacity and cycling stability. The activated vanadium oxides delivered a high specific capacity of 477 mA h g-1 at 50 mA g-1 and outstanding cycling stability with 97.7% capacity retention after 5000 cycles at 15 A g-1.

Zn/V2O5 Aqueous Hybrid-Ion Battery with High Voltage Platform and Long Cycle Life.

Aqueous zinc-ion batteries attract increasing attention due to their low cost, high safety, and potential application in stationary energy storage. However, the simultaneous realization of high cycling stability and high energy density remains a major challenge. To tackle the above-mentioned challenge, we develop a novel Zn/V2O5 rechargeable aqueous hybrid-ion battery system by using porous V2O5 as the cathode and metallic zinc as the anode. The V2O5 cathode delivers a high discharge capacity of 238 mAh g-1 at 50 mA g-1. 80% of the initial discharge capacity can be retained after 2000 cycles at a high current density of 2000 mA g-1. Meanwhile, the application of a "water-in-salt" electrolyte results in the increase of discharge platform from 0.6 to 1.0 V. This work provides an effective strategy to simultaneously enhance the energy density and cycling stability of aqueous zinc ion-based batteries.