Alumina modified sodium vanadate cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have great prospects for widespread application in massive scale energy storage. By virtue of the multivalent state, open frame structure and high theoretical specific capacity, vanadium (V)-based compounds are a kind of the most developmental potential cathode materials for ZIBs. However, the slow kinetics caused by low conductivity and the capacity degradation caused by material dissolution still need to be addressed for large-scale applications. Therefore, sodium vanadate Na_(2)V_(6)O_(16)·3H_(2)O (NVO) was chosen as a model material, and was modified with alumina coating through simple mixing and stirring methods. After Al_(2)O_(3) coating modification, the rate capability and long-cycle stability of Zn//NVO@Al_(2)O_(3) battery have been significantly improved. The discharge specific capacity of NVO@Al_(2)O_(3) reach up to 228 mAh/g (at 4 A/g), with a capacity reservation rate of approximately 68% after 1000 cycles, and the Coulombic efficiency (CE) is close to 100%. As a comparison, the capacity reservation rate of Zn//NVO battery is only 27.7%. Its superior electrochemical performance is mainly attributed to the Al2O3 coating layer, which can increase zinc-ion conductivity of the material surface, and to some extent inhibit the dissolution of NVO, making the structure stable and improving the cyclic stability of the material. This paper offers new prospects for the development of cathode coating materials for ZIBs.

Progress on Li3VO4 as a Promising Anode Material for Li-ion Batteries

Vanadium oxide Li3VO4 has attracted much attention as anode material for Li-ion batteries in recent years since it has a low and safe redox potential （vs. Li metal）, high specific capacity and its cost is low. However, the poor electronic conductivity and initial low coulombic efficiency limit its practical application. In this mini-review, the state-of-the-art results associated with Li3VO4 are summarized including structure, lithium insertion mechanism, preparation, modification, and electrochemical properties. Finally, the challenges and prospects are also discussed.

An Aqueous Asymmetric Supercapacitor Based on Activated Carbon and Tungsten Trioxide Nanowire Electrodes

An asymmetric supercapacitor （ASC） was assembled by using an activated carbon as positive electrode and WO3 nanowire as negative electrode, and its electrical performances were tested in voltage windows ranging from 0 to 1.5 V. A high specific capacitance of 51 Fog-1 could be achieved at the current density of 0.25 A·g-1 . Moreover, the ASC displays a good cycling stability with 86% of capacitance retention after 800 cycles, its energy density can be up to 11.9 Wh·kg-1 at the power density of 210 W·kg -1, and remains 7.7 Wh·kg-1 at a power density of 1250 W· kg-1. The excellent electrical performance is perhaps due to the crystal orientation of （001） planes for the WO3 nanowire, which favors the rapid reaction between W（VI） and H＋ cations. This aqueous asymmetric WO3//AC supercapacitor is promising for practical applications due to its easy preparation of WO3.

Latest Advances in High-Voltage and High-Energy-Density Aqueous Rechargeable Batteries

Aqueous rechargeable batteries(ARBs)have become a lively research theme due to their advantages of low cost,safety,environmental friendliness,and easy manufacturing.However,since its inception,the aqueous solution energy storage sys-tem has always faced some problems,which hinders its development,such as the narrow electrochemical stability window of water,poor percolation of electrode materials,and low energy density.In recent years,to overcome the shortcomings of the aqueous solution-based energy storage system,some very pioneering work has been done,which also provides a great inspiration for further research and development of future high-performance aqueous energy storage systems.In this paper,the latest advances in various ARBs with high voltage and high energy density are reviewed.These include aqueous rechargeable lithium,sodium,potassium,ammonium,zinc,magnesium,calcium,and aluminum batteries.Further chal-lenges are pointed out.