Ultrasonic Spray Preparation Of Spherical Poly Anionic Lithium Ion Battery Cathode Material Preparation Technology

Poly anion type cathode material such as lithium iron phosphate and lithium iron silicate has attracted an increasing attention due to their potential application in lithium ion battery.These materials have possessed many superior properties,such as good thermal safety?excellent cycle stability?environmental benignity and low cost in favour of industrialization as well.Unfortunately,it suffers from limited development in field of practical utility especially usage for EV application,because of their low electrical conductivity,low lithium diffusion rate and the difficulties of preparation,effectively problems many.In an attempt to overcome the significant drawbacks,several strategies have been exploited including controlling particle size,carbon coating.In this work,the ultrasonic spray method is applied for preparation of LiFePO4/C or Li2FeSiO4/C spherical particle,in which focuses on carbon content?the ratio of reactant and particle morphology.Main contents are as follows.Firstly,we briefly introduce the basic operating principle of ultrasonic spray and the design of ultrasonic spray equipment in our work.In addition,ultrasonic spray method has many advantage over spray drying and flame pyrolysis technique.Through solution ratio,spray temperature and sintering process investigated systematically,the better preparation procedure of ultrasonic spray was summered.Using the method of ultrasonic spray,the obtained material is provided with the high of balling rate,controllable uniform carbon coating,consistency and repeatability.The ultrasonic spray way is desired for meeting the demand proposed by the preparation of lithium iron phosphate and iron phosphate,such as the effect of carbon coating and high demand of solution ratio.Secondly,the effects of carbon source,carbon content and ratio of reactants on the electrochemical performances of LiFePO4 are investigated systematically.The crystal structure and surface morphologies of samples is characterized by XRD and SEM techniques.Based on the analysis from the relationship between the microstructure and the electrochemical performances,the optimal preparation condition for spherical LiFePO4/C by ultrasonic spray in our work is correspondingly obtained.Thirdly,according to the preparation of spherical LiFePO4/C particles,the spherical Li2FeSiO4/C composites are also fabricated and the effect of carbon content on the electrochemical performances is investigated.It is found that the as-prepared spherical Li2FeSiO4/C exhibits good electrochemical performances at low current densities.In summary,ultrasonic spray is proved to be an effective mass synthesis for the excellent-performances of Li2FeSiO4/C or LiFePO4/C as cathode materials for lithium ion batteries.