Preparation And Aluminum Ion Storage Mechanism Of Ti-based Oxides

Aqueous aluminum ion batteries are considered to be one of the best candidates for the next generation of advanced energy storage devices because of their low cost,safety,environmental protection,and high theoretical capacity.However,the current materials that can be used as anodes for aqueous aluminum ion batteries are quite comparable.Titanium dioxide is considered to be a promising anode material for aqueous aluminum ion batteries because of its stable structure and low redox potential.However,titanium dioxide has disadvantages such as poor electronic conductivity,unstable cycle performance,and low capacity.This research paper studies how to improve a series of problems such as low capacity and poor cycle stability of titanium dioxide anode materials.The specific research contents are as follows:Firstly,The nitrogen-doped titanium dioxide（N-TiO₂）anode material was successfully prepared by a simple sol-gel method.The research results show that the N-TiO₂ after an annealing treatment at 450℃has a smaller particle size,its crystallinity,and electronic conductivity.At a current density of 3 A g^-1,the electrode has a charging capacity of 43.2 mA h g^-1 at the first lap,and it still maintains a reversible capacity of 16mA h g^-1 after 100 cycles.The study on the aluminum ion diffusion kinetics of the electrode shows that the nanostructured N-TiO₂ sample annealed at 450℃has a fast aluminum ion diffusion rate,low charge transfer resistance and high electronic conductivity,making it have better aluminum ion storage performance.Secondly,A solvothermal method was used to prepare an anatase-type nano-leaf titanium dioxide anode material.Compared with commercial anatase titanium dioxide electrodes,the nano-leaf titanium dioxide electrode has excellent aluminum storage performance,and its initial charging capacity is 92.1 mA h g^-1（2.3 times that of commercial anatase titanium dioxide electrodes）,even after 100 cycles,its capacity is still much higher than that of commercial anatase titanium dioxide electrodes.The kinetic study results show that the excellent aluminum ion storage performance of the nano-leaf titanium dioxide electrode is attributed to the fact that the energy storage process is dominated by ion diffusion,and has a fast ion diffusion rate and low charge transfer resistance,which greatly improves The kinetics of the deintercalation reaction of Al³⁺in the electrode.Finally,The feasibility of Ti vacancy titanium dioxide induced by Cl was predicted through first-principles calculations,and Ti_0.95□_0.05O_1.79Cl_0.08（OH）_0.13 anode material was successfully synthesized.The electrochemical performance test shows that Ti_0.95□_0.05O_1.79Cl_0.08（OH）_0.13 electrode can obtain a high reversible capacity of 114.8 mA h g^-1after 10 cycles of activation at a high current density of 3 A g^-1,Even after 110 cycles,it still has a reversible capacity of 64 mA h g^-1.Ex-situ characterization technology proves that the Al³⁺storage behavior of Ti_0.95□_0.05O_1.79Cl_0.08（OH）_0.13 electrode is completely controlled by ion diffusion.During the discharge process,Al³⁺is preferentially embedded in Ti vacancies and then embedded in 110 crystal planes.In the lattice gap,Al³⁺is reversibly released in one step during the charging process.