Preparation And Electrochemical Performance Of Lithium Titanate Based On Industrial Metatinic Acid

As a new negative electrode material for lithium batteries with great development and application potential,spinel Li₄Ti₅O₁₂（LTO）is a kind of"zero-strain"semiconductor material featured by almost constant,volume in the process of charge and discharge,outstanding safety performance and long lifespan.However,the comprehensive performance of Li₄Ti₅O₁₂ is greatly affected by its poor basic conductivity of Li₄Ti₅O₁₂.Meanwhile,the nano titanium dioxide or organic titanium salt being used as the main titanium source for the synthesis of high performance Li₄Ti₅O₁₂ is quite expensive.Therefore,with the purpose to reduce cost while improving efficiency,it is necessary to further seek low-cost titanium base raw materials and preparation technology.For the sake of prepareing Li₄Ti₅O₁₂ based on the main titanium source of low-cost industrial metatinic acid through simple spray drying assisted high temperature solid phase method.This research performed surface coating and doping modification of Li₄Ti₅O₁₂,so as to explore the appropriate preparation process and effective modification method of Li₄Ti₅O₁₂by taking industrial metatinic acid as titanium source.In this research,the Li₄Ti₅O₁₂ anode material with fabulous electrochemical performance was obtained.The research contents are summarized as follows:（1）Based on the titanium sources of industrial metatrinic acid and nano titanium dioxide,Li₄Ti₅O₁₂ anode materials ALTO and PLTO were prepared throuth spray drying assisted high temperature solid phase method,both of which later presented good spherical morphology.According to the electrochemical performance test the specific capacity of PLTO was 170.00m Ah g^-1 at 0.2 C,just close to the theoretical specific capacity.Below 2 C,the specific capacity of PLTO remained above 130.00 m Ah g^-1,manifesting superior performance to ALTO under the condition of low rate current density.However,under 5 C and 10 C,PLTO and ALTO showed poor specific capacity lower than 100 m Ah g^-1,which was caused by the poor pure Li₄Ti₅O₁₂ electrical conductivity.Especially that such performance was greatly impacted in large current charging and discharging.To solve this,it is needed to improve the performance by optimizing Li₄Ti₅O₁₂.Considering cost control and comprehensive performance balance,industrial metatinic acid is more suitable for being applied as the base material.（2）On the basis of the research in（1）,Li₄Ti₅O₁₂/C-S composites were prepared by using the novel rice husk carbon landfill preparation technology with industrial metatinic acid as titanium source and glucose as carbon source under the carbon reduction atmosphere.The decomposition of glucose effectively reduced the particle size and the agglomeration of the sample surface.The prepared sample had a spherical porous structure,and when the glucose content was 15 wt%,the sample surface was covered with uniformly thin carbon nanolayers,which was conducive to the migration of lithium ions and improves the conductivity of the material.In addition,under the atmosphere of carbon reduction,the SO₄^2-adsorbed by industrial H₂Ti O₃ not only promoted the carbonization of glucose,but also formed a partial C-S bond coating on the surface of LTO after a series of reactions with glucose in the process of calcination,which significantly improved the overall conductivity of the material and the diffusion coefficient of lithium ion.The composite ALTO-0.15 displayed brilliant high specific capacity and cycle stability.Its specific capacity was 135.88 m Ah g^-1 at 10 C,and the capacity retention was 88.68%after 1000 cycles at 5 C.（3）Based on the research in（2）,iron-doped and carbon-coated LTO composite was prepared under the condition that iron-containing industrial H₂Ti O₃ was used as titanium source,15wt%glucose was added as carbon source,and rice husk carbon was buried to form carbon reduction atmosphere.X-ray diffraction,Rietveld refinement and EDS tests showed that the doped Fe²⁺partially replaced Ti⁴⁺,which promoted the increase of LTO cell parameters and cell volume,and was conducive to the diffusion and migration of Li⁺and electrons in the material.It is also found that when doping appropriate amount of Fe,the primary particle size of the sample can be effectively reduced by inhibiting agglomeration,which further significantly promoted the comprehensive electrochemical performance on the basis of（2）.The electrochemical test results showed that the discharge capacity of FLTO-1 reached 153.79 m Ah g^-1 at 10 C,and the capacity retention rate was 92.56%after 1000 cycles at 5 C.According to EIS test,FLTO-1 demonstrated the smallest Rct value and its lithium-ion diffusion coefficient was 5.95×10^-13 cm² s^-1.The above research results lay a good technical foundation for the large-scale application of LTO materials.