Lithium-ion Battery Anode Materials Prepared By Molten Salt Method And Their Electrochemical Properties

Due to the growth of energy demand,lithium-ion batteries with high energy density and long cycle life will be widely used in the next decades.However,in recent years,the commercialized anode materials are still graphite based carbon materials,which are difficult to meet the high demand of the new generation of people for lithium-ion battery capacity equipment.Therefore,it is an inevitable trend to develop new high-capacity and environment-friendly electrode materials.Metal oxide is considered as a substitute for the new generation of graphite anode because of its high theoretical specific capacity.However,its rapid capacity attenuation due to volume expansion has seriously restricted its practical application.In order to improve the current situation,people usually nano metal oxide or composite it with high conductivity materials to alleviate the pulverization caused by volume expansion and improve the lithium storage performance of battery.In view of this situation,this paper mainly uses molten salt method to prepare nanostructured germanium based,cerium based and tin based metal oxides.In order to further improve the battery performance,glucose is used to prepare composite materials.The synthesis mechanism and battery performance of the three metal oxides and composite materials are analyzed and discussed.(1)Using GeO₂ as the main raw material,KCl and LiCl as reaction salt medium,zinc germanate as anode material for lithium-ion battery was prepared by a simple one-step solid-state chemical reaction method by molten salt method.The effect of calcination temperature on the morphology of Zn₂GeO₄ was investigated.The results of SEM show that Zn₂GeO₄ nanoparticles with nanometer size were synthesized at 540?for 4 h.The crystallinity and structure of the synthesized products were characterized by X-ray diffraction,which showed that the samples were pure phase.Field emission electron microscopy was used to observe the morphology and size of the samples.The results showed that the yield of nano particles was more than 90%.The electrochemical results show that the capacity retention rate of Zn₂GeO₄ nanoparticles can be maintained at a high level,which has good cycle stability.In order to improve the cycle and rate properties of Zn₂GeO₄ nanomaterials,Zn₂GeO₄/C composites with 10%and 20%carbon content were prepared by calcining the mixture of Zn₂GeO₄ and glucose.The electrochemical results show that the capacity retention rate and rate performance of the composite are improved,which indicates that the carbon coating is helpful to improve the performance of raw materials and battery performance.(2)Using Ce(NO₃)₃·6H₂O as the main raw material,KCl and LiCl as the reaction salt medium,cerium oxide,Cerium oxide as anode material for lithium ion batteries was prepared by a simple and high yield solid state chemical reaction method by molten salt method.The effect of calcination temperature on the morphology of CeO₂ was investigated.The results of SEM show that nano sized CeO₂ particles were synthesized at 540?for 4 h.X-ray diffraction results show that the samples are pure phase,and field emission electron microscopy results show that the samples are nanostructures.The electrochemical results show that the nanostructured CeO₂ material has excellent cycle stability and reversibility.In order to further improve the battery performance of CeO₂ nanomaterials,CeO₂/C composites were prepared by calcining the mixture of CeO₂ and glucose.The electrochemical results show that the capacity retention and rate properties of the composites are improved,After 300cycles,the discharge capacity of 178.4 m Ah/g is much higher than that of raw material(165.8m Ah/g),and the effective capacity is 212.1 m Ah/g under unstable current.(3)Tin oxide as anode material for lithium ion battery was prepared by molten salt method using anhydrous SnCl₂ as main raw material,KCl and LiCl as reaction salt medium.On the basis of the front studies,the SEM results show that nano-sized SnO₂ particles were synthesized at 540?for 4 h.X-ray diffraction results show that the samples are pure phase,and field emission electron microscopy results show that the samples are nanoparticles.In order to improve and compare the cycle performance and rate performance of SnO₂nanomaterials and composites,SnO₂/C composites were prepared by calcining the mixture of SnO₂ materials and glucose.The electrochemical results show that the capacity retention and rate properties of the composites are higher than those of the raw materials,After 300 cycles,it still has a discharge capacity of 139.2 m Ah/g and an effective capacity of 497.6 m Ah/g under unstable current,which shows better performance than the raw materials.