Research On The Construction And Performance Of Zinc-tungsten Oxide Electrochemical Energy Storage Device Based On ZnCl₂ "Water-in-salt" Electrolyte

Aqueous zinc ion batteries are highly promising electrochemical energy storage devices with the advantages of high safety,environmental friendliness,and low price.However,traditional aqueous electrolytes suffer from a narrow electrochemical stability window and the dissolution of active mass.The water-in-salt strategy can broaden the electrochemical stability window and inhibit the dissolution of active mass.Tungsten oxide has proven to be a good electrochemical lithium storage material due to its open lattice network structure and excellent electrochemical ion insertion/extraction properties.However,pure WO₃materials have rarely been reported as cathode materials for zinc ion batteries due to factors such as poor structural stability and low specific capacity.In this thesis,we explore two aspects of electrolyte regulation as well as cathode material design to enhance the charge/discharge performance of zinc-tungsten oxide batteries.1.The advantages of 30 m ZnCl₂water-in-salt electrolyte in broadening the electrochemical stability window,suppressing electrochemical corrosion,uniform nucleation,and reducing the desolvation energy barrier were found by comparing linear scanning voltammetry,chronoamperometry,Tafel curves,nucleation overpotential,and impedance tests in 30 m ZnCl₂walt-in-salt electrolyte,conventional aqueous zinc ion electrolyte,and zinc ion organic electrolyte.2.The Zn–WO₃battery was assembled by using a ZnCl₂water-in-salt electrolyte,which broadened the electrochemical stability window while inhibiting the dissolution of tungsten oxide,and the capacity and stability of the battery were improved.the assembled Zn–WO₃battery with 30 m ZnCl₂water-in-salt electrolyte achieved a specific capacity of 94.8 m Ah g^-1at 0.1 A g^-1,energy density of 18.9 Wh kg^-1at a power density of 747.3 W kg^-1,and capacitance retention of 94.8%after 1,000 cycles at a high rate of 1 A g^-1.Furthermore,a flexible quasi-solid-state Zn–WO₃battery was fabricated using ZnCl₂water-in-salt electrolyte without adding adhesives,demonstrating great potential for the next-generation flexible wearable energy storage application.3.The WO₃·2H₂O material was prepared by inserting interlayer water molecules into the lattice of WO₃material.The insertion of crystalline water molecules increased the lattice spacing of WO₃and widened the diffusion channel of Zn ions,which transformed the original Zn-WO₃battery properties into pseudocapacitance characteristics.The constructed Zn-WO₃·2H₂O pseudocapacitor exhibited excellent rate capability and cycling stability,maintaining 86.3%of the initial capacity after10,000 charge/discharge cycles.