LiMn 0.8 Fe 0.19 Mg 0.01 PO 4 /C Cathode Material Was Synthesized By Microwave Method

Lithium ion batteries have been used widely in many fields of social life which have higher requirements on the performance of lithium ion batteries.All of materials in lithium ion batteries,the cathode materials have a more direct impact on cost and performance for lithium ion battery products.So the development of low cost,high security,green environmental protection and high performance cathode material has very important significance.Olivine-structured LiMnPO4 cathode materials have advantages of high voltage with 4.1 V,low cost,excellent safety performance and resistance to overcharge performance,which are concerned by more and more people.But the electronic structure of LiMnPO4 band gap is 2 eV show the characteristics of insulators,the electronic conductivity and ionic conductivity is very low.Team early by carbon coating and Fe,Mg metal ion doping methods of study in this formula LiMn0.8Fe0.19Mg0.01PO4/C,the material has excellent electrochemical performance.The traditional heat conduction heating mode has the high energy consumption,long time,and microwave heating has the advantages of efficient,safe and free from contamination.The LiMn0.8Fe0.19Mg0.01PO4 samples were synthesized by a microwave heating process,and for the purpose of improving the electrochemical performance.And explore the different sintering temperature,heating rate,holding time and carbon content,two steps and ball mill again after sintering on the influences of material structure,morphology and electrochemical performance.Then we modified to the ball mill process of precursor,through change the ball in ball mill grinding of liquid-solid ratio,adding different solvents,replacement of different carbon source,we discussed the material structure,morphology and electrochemical performance.Research found that the synthetic LiMn0.8Fe0.19Mg0.01PO4/C cathode material had the best electrochemical performance when the sintering temperature was at 800 ?.Heating power has the certain influence on LiMn0.8Fe0.19Mg0.01PO4/C material particle size and micromorphology.The material has the best electrochemical performance,when heating power was 25%of the rated power.LiMn0.8Fe0.19Mg0.01PO4/C material first charge and discharge specific capacity is around 140 mA · h · g-1 at different holding time.The carbon content has almost no influence on the material electrochemical properties at the condition of small rate charge and discharge.First charge and discharge and cycle performance of two steps decreased slightly compared with the direct heating performance.The method of ball mill again after sintering has a bigger impact on LiMn0.8Fe0.19Mg0.01PO4/C material particle size and microstructure.Ball mill again after sintering process can lead to part of the secondary particles reunite together to form larger particles,leading to lithium ion transport slow,performance declines.We have the ball mill process of precursor was improved.There is no impurity phase when liquid-solid ratio of was 1:4,so the material had good electrochemical performance.But the impurity phase would generate,when the liquid-solid ratio was 1:2,which had a great effect on the crystal structure and properties of materials.Adding solvent when ball mill has certain influence on material particle size and morphology.The material has good electrochemical performance,when ethanol as solvent.Sucrose as carbon source to synthesize sample has good electrochemical performance,citrate as carbon source,it is difficult to coat on the surface particles and lead to poor electrochemical performance.