Application Of Ultrasonic Spraying In The Preparation Of Lithium Ion Battery

Due to its high voltage,high density and excellent cyclic stability,lithium-ion batteries have been widely applied in mobile phones,computer,digital cameras,electric vehicles?EV?,hybrid electric vehicles?HEV?and plug-in hybrid electric vehicles?PHEV?.Cathode materials and anode materials are the important components for lithium-ion batteries.Simple synthesis of active materials and surface-modification are highly desirable for industrial production in the lithium-ion batteries field.In our work,preparation of hollow Li₄Ti₅O₁₂ spherical materials and fabrication of cathode electrode with surface-modification are carried out with a simple ultrasonic spraying.The microstructures of the as-prepared composites are characterized with X-ray diffraction and scanning electron microscopy.The electrochemical performances are carried out by charge-discharge tests,AC impedance tests and cyclic voltammetry.The main contents are as follows:First,Li₄Ti₅O₁₂ nanoparticles were synthesized by ultrasonic spraying using lithium carbonate and isopropyl titanate as precursors,followed by calcination at various temperatures.The structure and morphology of the as-synthesized materials were characterized by XRD and SEM.The electrochemical performances were systematically investigated by charge-discharge testing,cyclic voltammetry and AC impedance tests.The obtained results show that the as-prepared samples have hollow spherical structure,and exhibit best cyclic stability and rate performances when the composites are calcinated at 750 ?.Analysis from the electrochemical measurements reveals that the sample calcinated at 750 ? has largest specific surface area,which increases the contact area between active materials and electrolyte,reduces Li-ion diffusion length.Second,TiN particles in the suspension were deposited on the surface of lithium-iron-phosphate electrode of 18650-type lithium-ion batteries using ultrasonic spraying method.SEM images reveal that TiN particles are uniformly dispersed on the LiFePO₄ electrode.The 18650 type lithium iron phosphate batteries are assembled using graphite carbon as the negative electrode,and the electrochemical performances are correspondingly carried out.In comparison,the batteries surface-modified with TiN-coating demonstrates smaller inner resistance and better rate performances.