The Exploration Of Cathode Materials And Revelation Of The Mechanism For Non‐aqueous Aluminum Ion Batteries And Aqueous Aluminum Ion Batteries

In recent years,it has triggered tremendous demands in batteries owing to the rapid development of portable electronic devices and new energy vehicle industry.However,the scarcity of lithium resources and the skyrocketing prices will threaten the usability of future lithium-ion batteries for the sharply increasing market.Rechargeable aluminum-ion batteries are deemed to be most attractive alternatives due to their distinctive advantages,such as rich reserves,low cost,high safety and high energy density.In view of the solvent type in the electrolyte,aluminum-ion batteries could be divided into non‐aqueous and aqueous.The studies on non‐aqueous aluminum-ion batteries and aqueous aluminum-ion batteries are both in its infancy stage of development.And storage energy mechanisms are not yet clear.The development of cathode materials with high-performance for aluminum-ion batteries and in-depth study of the energy storage mechanism are identified as the focus of future research.In this paper,two cathode materials are synthesized and corresponding electrochemical performances are tested.In addition,the working mechanisms are well elucidated.This paper is helpful for reference to design and build the aluminum-ion batteries with high energy density and long cycle stability.The specific content is as follows:（1）Fe Te₂ wrapped with graphene oxide（GO）nanocomposite via a simple hydrothermal routine is firstly reported as the cathode material for AIBs.The electrochemical properties are investigated in this paper.Finally,in order to better understand the working process of this battery system,the energy storage mechanism of Fe Te₂ cathode in non‐aqueous aluminum-ion batteries is systematically explored by experiment combined with theory.Firstly,a full battery using aluminum sheet as the battery anode and Fe Te₂@GO as the battery cathode is assembled.Conspicuously,the electrode of hybrid composite exhibits outstanding long-term cycle performance with a reversible capacity of 120 m A h g^–1 at 1A g^-1 after 10000 cycles,which is significantly superior to all the reported transition metal chalcogenide to date.In addition,the storage energy mechanism and the foundational reason of the excellent cycle performance of Fe Te₂ based non‐aqueous aluminum-ion batteries are elucidated by a series of systematic experimental characterizations,and the result indicates that this process involves the intercalation and deintercalation of multi-ions(Al Cl₄^-,Cl^-and Al³⁺).The feasibility of the three carriers was then further validated theoretically by theoretical calculations.This work is expected to provide fresh perspectives and more thorough insights into exploration of competent cathode material with high electrochemical performance and charge storage mechanism for non‐aqueous aluminum-ion batteries.（2）The NH₄V₄O₁₀ micron material was synthesized by a solvothermal method and applied to aqueous aluminum ion batteries for the first time.The excellent performance is associated with the large layer spacing of NH₄V₄O₁₀ material which creates conditions for reversibility of carriers intercalation and extraction.In addition,the electrochemical mechanism of NH₄V₄O₁₀-based aqueous aluminum ion batteries has been investigated by X-ray photoelectron spectroscopy and X-ray diffraction techniques.From the perspective of elemental valence changes and crystal structure evolution at different potentials during charging and discharging,it is concluded that the intercalation and de-intercalation of Al³⁺is accompanied by redox of V⁵⁺/V³⁺in aqueous aluminum ion batteries based on NH₄V₄O₁₀cathode material.This work is an important reference for the exploration of cathode materials for aqueous aluminum ion batteries and understanding of the charge storage mechanism of aqueous aluminum ion batteries.