However, the organic electrolytes used in LIBs are highly toxic and flammable, and are deemed safety hazards. The limited resources and high-cost of lithium and harsh assemble conditions of LIB cells also hinder the application of LIBs in large-scale energy storage systems. [2] P. Rüetschi proposed the '3 E' criteria including Energy, Economics, and Environment to determine whether the battery system was practical for daily use. [3] Aqueous electrolytes with low price, high safety, and high conductivity can drastically reduce the production cost and improve battery safety. [4] Aqueous zincion batteries (ZIBs) use Zinc as an environment-friendly anode which shows low redox potential (−0.78 eV vs SHE), high electronic conductivity as well as large capacity (820 mAh g −1 and 5851 mAh cm −3 ). [5,6] Therefore, ZIBs are considered as one of the most competitive and promising development directions for next-generation large-scale energy storage. As the initial work in mild aqueous electrolyte, an aqueous ZIB with MnO 2 cathode and Zn anode was reported by Kang and co-workers in 2012. [7] Since then, research interests in ZIBs area develops burgeoningly and more than 1000 research papers about electrode materials on aqueous ZIBs were published.The commonly reported cathode materials are V-based compounds, [8,9] manganese oxides, [10,11] Prussian blue analogs, [12,13] metal chalcogenides, [14,15] and organic compounds. [16,17] Among them, manganese oxides have moderate operating potential and high theoretical capacity, but suffer from manganese dissolution in aqueous electrolytes due to Jahn-Teller dissolution of Mn 3+ , which leads to structural collapse and poor cycling stability. [10,11] Prussian blue analogs often process high operating potential beyond 1.5 V and their open cage-like framework guarantees structure stability under rapid Zn 2+ transmission, leading to good rate performance and long-cycle capacity retention. However, the large framework structures also bring limited theoretical capacity and suffer from O 2 evolution due to the high operating potential. [13,18] Organic cathodes process passable theoretical capacity, high structural diversity, and flexibility, bringing potential prospects in flexible electrodes. But the high dissolubility in electrolytes and high resistance are two bumps to overcome for organic cathodes used in ZIBs. [16,17] V-based compounds have received extensive attention as cathode for ZIBs due to the rich reserves and diversity of valences of vanadium as well as their general high theoretical capacity and Aqueous zinc-ion batteries (ZIBs) have been promptly developed as a competitive and promising system for future large-scale energy storage. In recent years, vanadium (V)-based compounds, with diversity of valences and high electrochemical-activity, have been widely studied as cathodes for aqueous ZIBs because of their rich reserves and high theoretical capacity. However, the stubborn issues including low conductivity and sluggish kinetics, plague their smooth application in aqueous...

Conversion‐type cathodes for aqueous zinc ion batteries (ZIBs) can provide flat plateau slop and stable output potential, compared to general intercalation‐type cathodes. The high volumetric capacity and stable output potential of Te make it a promising cathode for ZIBs, but sluggish kinetics and large volume change hinder its further application. To address these issues, we revisit fully zinced ZnTe and construct ZnTe/rGO composites as the new conversion‐type cathode. The electrode undergoes a solid‐to‐solid conversion reaction and shows a stable output potential with ultra‐flat discharge plateau slop of 0.09 V (Ah g−1)−1. When ZnTe is de‐zinced and transformed to Te during charge process, it has a volume shrinkage which generates empty space in graphene matrix for latter volume expansion of Te. The graphene matrix also improves conductivity and reaction kinetics of the cathode. Due to the combination of pre‐zincation of ZnTe, graphene matrix and the elimination of “shuttle effects” process, ZnTe/rGO electrode exhibits a high and stable capacity of 186 mAh g−1 at 500 mA g−1 after 300 cycling, with almost no decay after initial 10 cycles.

No abstract

Vanadium dioxide (VO2(B)) is a proper cathode for aqueous zinc‐ion batteries (ZIBs) due to its shear structure and high theoretical capacity. However, the sluggish kinetics and structure instability derived from the strong electrostatic interaction between Zn2+ and the VO2 host hinder its further application. Defect engineering is a useful way to circumvent the limitations. Herein, oxygen‐defect VO2 (Od‐VO2) with tunable oxygen vacancy concentration are obtained via a facile one‐step hydrothermal method by adjusting ascorbic acid addition. It is proved that oxygen vacancies can provide extra active sites for Zn2+ storage and reduced electrostatic barrier for Zn2+ transportation, but excessive vacancy content would lead to a reverse effect. The Od‐VO2 cathode with optimum oxygen vacancy concentration achieves an outstanding performance with a high capacity of 380 mAhg−1 at 0.2 A g−1, excellent cycle stability with 92.6 % capacity retention after 2000 cycles at 3 A g−1 and a high energy density of 197 Wh kg−1 at the power density of 0.641 kW kg−1. Therefore, this defect engineering method for Od‐VO2 provides an attractive way for high‐performance aqueous ZIB cathodes.

No abstract