Preparation Of Titanium Dioxide Hollow Sphere Materials And Research On Lithium Battery Performance

Lithium-ion batteries are widely used in electronics and automotive products.They are the main direction of new energy technology development.Nanostructures of anode materials are usually designed in lithium-ion batteries to improve their electrochemical performance.However,the poor cycle efficiency,short cycle life,and low specific capacity not only reduce the range of use of lithium-ion batteries,shorten the service life,but also seriously affect the service safety of the battery.Studies have shown that by preparing mesoporous nano-hollow spheres,the volume expansion in the charging and discharging process of lithium ion batteries can be reduced,and the rapid extraction and insertion of lithium ions can be improved,thereby significantly improving the lithium storage performance and cycle stability of lithium ion batteries.Among the negative electrode materials of lithium ion batteries,the semiconductor transition metal oxide TiO₂ is considered to be one of the ideal anode materials for lithium ion batteries due to its low toxicity,structural stability and excellent charge-discharge cycle performance.But so far,the deposition process of mesoporous TiO₂ nano-hollow spheres is still unclear and lacks systematic recognition.Although many researches and mechanisms have been proposed for the preparation of mesoporous TiO₂ hollow spheres,most of them focus on their photoelectric properties.The research on its lithium b attery is not systematic.In addition,mesoporous TiO₂ hollow spheres have lower conductivity,Li⁺diffusivity and specific capacity(such as the theoretical specific capacity of anatase TiO ₂ is only335 mAh·g^-1),which seriously restricts the performance improvement and development of lithium ion batteries.application.Therefore,in this study,the mesoporous hollow sphere structure was used as the research object.Firstly,the mesoporous TiO₂ hollow spheres were prepared,and the effects of different deposition time and reaction time on the mesoporous TiO ₂ hollow sphere structure were analyzed and electrochemically tested.Find the best process parameters.It is found that the sample with stable structure and good electrochemical performance is coated with graphite carbon,which not only improves the conductivity of electrons and ions,but also plays a role in structural protection due to the penetration of graphite.The following main research conclusions were obtained:?1?The effects of different deposi tion times on the structure of mesoporous TiO₂hollow spheres were investigated.It is found that within the range of process parameters determined by the paper experiments,when the deposition time is less than 24 h,TiO₂ is difficult to adsorb onto SiO₂ particles,and exists in the form of scattered equiaxed crystals and particles.When the deposition time is more than 30 h,the mesoporous TiO₂ has different diameters.Due to the long deposition time,some hollow spheres continue to deposit and the diamet er is larger.When the deposition time is 24 h,the mesoporous TiO₂ hollow sphere electrode material with complete structure and particle size of about 600 nm is successfully prepared,and the optimal electrochemical performance is obtained.The first spec ific discharge capacity is 250mAh·g^-1.After 100 cycles,the capacity can still reach 175 mAh·g^-1,and at 5C current density,the capacity can still be maintained at 160.4 mAh·g^-1.?2?The effects of different hydrothermal time on the carbon content of mesoporous TiO₂ hollow spheres were investigated.Found within the set process parameters.When the hydrothermal time is 2 h,the graphite carbon layer coated by mesoporous TiO₂/GC hollow spheres is not uniform.When the water is hot for 6 h,the mesoporous TiO₂/GC hollow spheres,each TiO₂ nanoparticle is uniformly and uniformly coated by the 9.3 nm graphite carbon layer.Mesoporous TiO ₂/GC hollow spheres at 4 h in water,each TiO₂ nanoparticle was uniformly and uniformly coated with a 5.5 nm graphitic carbon layer,and the most excellent electrochemical performance was obtained.After 100 cycles of charge and discharge,the capacity remained.At 192 mAh·g^-1.