Controllable Preparation And Electrochemical Performance Of Vanadate-based Materials

Over the past decades,both traditional Li-ion batteries and emerging metal-ion batteries have become critical in driving the advancement of energy storage system.However,a major obstacle to the practical application of these technologies is the lack of appropriate and inexpensive electrode materials that can deliver high energy/power density,long-term cyclability,and high-rate capability.Looking back the history of searching suitable electrodes for battery technology,vanadate-based compounds feature with rich redox chemistry,displaying intriguing electrochemical properties and receiving significant attention in battery applications.Nevertheless,the intrinsic disadvantages of vanadate materials（such as low ion/electronic conductivity,sluggish reaction kinetics,large volume expansion of the conversion-type vanadate electrodes and so on）should not be ignored.Based on the prevalent design strategies for the synthesis of vanadate-based electrodes,therefore,we focus on the design and preparation of vanadate-based compounds,characterization,electrochemical performance,and their lithium/zinc storage mechanism,aiming to obtain suitable electrode materials that can provide superior wide-temperature electrochemical performance for energy storage devices,including lithium-ion battery and aqueous zinc ion battery.The meaningful achievements are summarized as follows:（1）In order to address the issues of large volume expansion and poor cycle stability of the conversion-type vanadate anodes in lithium-ion batteries,we successfully prepared a 3D porous hexagonal Co₂V₂O₇from a facile hydrothermal and combustion process.The optimum reaction time and the amount of Li OH was determined via investigation over the morphological evolution and phase transition of the precursor.Owing to its stable hexagonal prism structure and rich porosity,the P-CVO-HPs electrode exhibits a remarkable specific capacity,good long-term cycle stability and excellent rate in a wide range of temperatures.（2）In order to overcome the poor cycling stability of single-ion pre-intercalated hydrated vanadate materials in high-concentration aqueous electrolytes（especially in extreme environments）and the high cost of traditional synthetic processes,we have established a new conception of developing an effective yet a low-cost technology to synthesize vanadate-based compounds from vanadium slag waste towards energy storage application.In detail,a novel multi-ion pre-co-intercalated hydrate vanadate（M_xVOH）featuring robust host structure and high electrical conductivity has been successfully prepared.Moreover,it is also noted that the aqueous battery system by virtue of the improvement and innovation of the water-based electrolyte can improve the cycling durability of zinc metal anode and low temperature adaptability of aqueous electrolyte.As a result,this aqueous battery system exhibits excellent high-rate cycling stability at both room temperature and low temperature.