The Modification And Characterization Of Lithium-ion Battery Cathode

The lithium ion batteries now are getting more and more attention of researchers, due to its small size, light weight, high energy density, long life, high safety performance, cycle efficiency, environmental. Currently, commercial applications are mainly used in lithium-ion cathode material LiCoO2. However, due to its high cost, and Co is a toxic element, it is difficult for commercial large-scale power battery to use. Therefore, it is an urgent need to study other cathode materials to take place of LiCoO2. In this thesis, which lithium ion battery cathode materials containing Mn, LiMn2O4 was researched by synthesis conditions and modified, to try to improve on the electrochemical properties of the battery. This paper is as follows:1. Using hydrothermal method to coat LiMnPO4 on the surface of the commercial grade LiMn2O4, as the composite cathode material. Experiment to examine the impact of different synthesis conditions on LiMnPO4 cathode material morphology, respectively, in the range of reaction temperature, reaction time, reaction concentration and reaction solvent. The study showed that the lwt% LiMnPO4 coated LiMn2O4 has greatly improved electrochemical performance at both 25? and 55?. At charge-discharge rate of 1C, the first discharge capacity is 114 mAh · g-1, capacity retention is 96%. After 50 cycles at room temperature,then heated to 55? continue 50 cycles, the ultimate capacity of 109mAh · g-1,96% of the initial capacity.2. Sol-gel method prepared by AZO on the surface of LiMn2O4 which synthesising by spray drying. The experiments show that the the AZO coating treatment did not change the structure of LiMn2O4 material. At high-temperature, the charge-discharge rate is 1C, the 1.5 wt% AZO coated-LiMn2O4 maximum discharge capacity is 114.2 mAh · g-1, after 100 cycles the capacity is still 109.0 mAh · g-1, the capacity retention rate of 95.4%, higher than the 89.2% of the un-coated LiMn2O4.