Synthesis And Characterization Of Li₄Ti₅O₁₂ Based On Metatitanic Acid

In recent years,lithium ion batteries?LIBs?had witnessed the rapid development of lithium ion batteries?LIBs?,as a high-performance energy storage device,and hvae been widely used in electric vehicles,mobile devices,energy storage power stations and other fields.When spinel type Li₄Ti₅O₁₂?LTO?is used as the anode,the crystal structure of LTO remains highly stable and the volume is almost unchanged in the lithiation process,and thus it is called zero strain material.However,due to the rising price of Ti ore and the low electronic conductivity of LTO,further research is needed to reduce its cost and improve its electrochemical performance.The research in this thesis aims to optimize the preparation and modification of LTO based on the low-cost metatonic acid,study the optimal synthesis process and the modification method for the LTO preparation,and finally obtain high-performance LTO materials for LIBs.The main results work is summarized as follows:?1?LTO materials prepared by direct calcining?DC1-LTO?,secondary calcining?DC2-LTO?and after hydrothermal process with lithium acetate?HyT-LTO?based on metatonic acid.It was found by phase analysis that HyT-LTO shows higher degree of crystallization,smaller particles and less impurities.HyT-LTO showed the most excellent electrochemical performance.It is proved that the method can prepare high quality LTO materials for LIBs.?2?Different atmosphere plasmas were used to medify the LTO.Electrochemical performance tests,show that the electrochemical performance test found that,compared to other samples,the LTO+H₂+N₂ material treated with H₂ and N₂ has the highest reversible specific capacity,the most excellent electrochemical performance.According to the phase analysis,LTO has oxygen vacancy and N element injection after mixed plasma treatment of H₂ and N₂,which can effectively reduce the resistance of LTO material and improve the diffusion of Li-ion in the LTO phase.?3?graphene-coated LTO composite materials LTO@G?HT?and LTO@G?HT?with good electrochemical properties were successfully synthesized by thermal reduction and CVD methods.Compared with uncoated LTO and LTO@G?HT?,LTO@G?CVD?showed the most excellent electrochemical performance.