Preparation And Microstructure Properties Of Lithium Iron P Hosp Hate Cathode Materials With High Energy Density

To obtain LiFePO₄/C cathode materials with high capacity,high rate and good electrochemical performance,the LiFePO₄/C of cathode materials for olivine lithium ion battery was used as the main research object:1.LiFePO₄samples were prepared using two hydrothermal schemes,The optimum hydrothermal scheme was obtained by experiments,The specific capacity of lithium iron phosphate prepared by the optimal hydrothermal scheme reached80m Ahg-1 at 0.2C in electrochemical measurement.2.Pure phase lithium iron phosphate prepared by hydrothermal solution was used as precursor,and the carbon-coated lithium iron phosphate was synthesized by adding appropriate amount of glucose in subsequent calcination（6 h calcined under nitrogen protection 680℃）.As a result,the prepared lithium iron phosphate samples were filled and discharged 100 times at 2C,and the capacity retention was 70%.3.Carbon thermal reduction was used to prepare LiFePO₄/C,for the better electrochemical performance of lithium iron phosphate cathode materials,Effects of different carbon sources on preparation LiFePO₄/C were investigated.Experimental results show that the specific capacity and cycling stability of the material can be greatly improved by adding LiFePO₄/C composite carbon source（glucose,polyethylene glycol and citric acid）.The first discharge specific capacity of the material at 0.2C reaches 160m Ahg^-1,1C and its specific capacity can reach 150m Ahg^-1.Experimental results show that the LiFePO₄/C prepared by the composite carbon source has the best electrochemical performance.4.In order to explore the best technological parameters of the LiFePO₄/C,the effects of mechanical grinding and manual grinding on the properties of the final samples were investigated.Finally,it is concluded that the morp Hology and electrochemical properties of the LiFePO₄/C prepared by mechanical grinding precursor mixed samples are the best,The specific capacity at 0.2C reached 162m Ahg^-1,indicating that the electrochemical stability of the materials prepared by mechanical wet grinding is better.