Preparation And Electrochemical Properties Of Titanium-based Nanomaterials

With the unrestricted development and consumption of fossil energy accelerating the depletion of non renewable resources,leading to increasingly serious environmental pollution,the research of clean energy development is paid more and more attention.Due to the time and geographical constraints,natural resources such as wind energy,tidal energy and solar energy cannot be continuously developed and utilized.Therefore,the development of environment-friendly and high-performance energy storage system has become one of the important development tasks.With the rapid development of science and technology,lithium ion batteries are required to have higher energy density and power density.However,energy storage systems tend to be large-scale and low-cost development requirements.Compared with lithium-ion battery,sodium ion battery has more advantages in terms of low cost,which has been further developed.When evaluated as an anode material for lithium-ion batteries,titanium based compounds have important commercial development value.The most representative TiO₂and Li₄Ti₅O₁₂ show excellent cycle stability and has been used commercially.However,the poor electronic conductivity and low ion diffusion coefficient of Ti based materials limit their further development and application.At present,the methods such as doping,compounding with other materials,building transition metal titanate,etc.,utilize the synergy of various materials to enhance the electrochemical performance.In this paper,the Ti-based nanomaterials with different modification methods were designed and prepared,using electrospinning technology and solvothermal method,and the effects of different modification strategies on structure and properties were studied in detail.The contents of this paper are as follows:1. One-dimensional CoTiO₃/Co₃O₄/TiO₂ hybrid nanobelts,with coral-like morphology consisting of secondary Co₃O₄/TiO₂ nanoparticle building blocks uniformly distributed on the nanobelts,have been rationally designed and synthesized via a two-step electrospinning calcination strategy.The hybrid nanobelts were characterized by SEM and TEM,and the morphology and structure of the samples were analyzed.Combined with XRD refinement and XPS analysis of sample structure and composition.Through electrochemical performance test,the pseudocapacitor lithium storage mechanism of the sample was analyzed,and the nanocomposites exhibit excellent electrochemical performance.2. Electrospinning combined with oil bath reflux treatment was used to rationally prepare a composite nanomaterial composed of graphene?r GO?nanosheets wrapped in Fe₂TiO₅-TiO₂ nanofibers.The surface charge state of the sample was characterized by Zeta potential,and the mechanism of graphene coated with nanofibers was analyzed by FT-IR.Through HRTEM,it can be clearly seen that the graphene sheets are tightly anchored on the surface of the nanofibers.Compared with other samples,r GO-FTO-TO composite nanomaterials show excellent lithium storage performance,high discharge specific capacity at high current density,and show good stability and excellent rate performance.3. Lithium titanate nanofibers?LTCOB?co-doped with Cu and Br were designed and prepared based on electrospinning.The samples were characterized by XRD,SEM,TEM,EDS mapping,XPS and so on.LTCOB is a slubby fiber composed of nanoparticles connected with a diameter of 300?500 nm.Doping causes the increase in the cell parameters of the lithium titanate,enhances the electronic conductivity,and broadens the transmission channel of lithium ions.Through comparison between different samples,LTCOB electrode has higher rate performance and excellent cycle stability.4. The N-doped carbon-coated NTP nanoparticle composite material was prepared by using solvothermal method and calcination process,using chitosan as the carbon source to coat the sodium titanium phosphate?NTP?nanoparticles.The XRD,Raman,SEM,TEM and other test methods were used to characterize the morphology and structure.The introduction of the carbon layer suppressed the agglomeration of lithium titanate nanoparticles during the preparation process.Through the comparison of electrochemical tests,the impact of carbon coating on the performance before and after was analyzed.The carbon-coated NTP nanoparticles enhanced the sodium storage performance and showed good rate performance and cycle stability.