Study On Synthesis And Property Of Lithium Nickel Oxides As Cathode For Li-ion Batteries

Li-ion secondary batteries have a great prospect in application and exploitation as an interesting kind of electrical source. Improving and enhancing the electrochemical performance of batteries mainly depends on the change-discharge property of cathode electrode materials. Now the commercialized lithium-ion battery mostly uses LiCoO2 as cathode material, but cobalt suffers the disadvantage of limited resource, high price and heavy pollution to environment. Though LiMn2O4 enjoys the advantage of low-price, easy preparation and non-toxicity to environment, yet its cycle ability not good and specific capacity low, especially capacity fading under high temperature. While layered LiNiO2is the most promising cathode materials: plenty in resource, cheapness in price, high specific capacity and non-toxicity. But it is difficult to be synthesized, and its unstable structure results in rapid capacity fading and bad thermal stability. This thesis focuses on the study of the layered lithium nickel-based oxides as cathode materials lithium-ion batteries, the main aspects follow:1 Study on the synthesis and properties of LiNixCo1-xO2 by the sol-gel method Compared with solid-state method, sol-gel method enjoys the advantage oflower calcining temperature and small uniform particle size of products. After the XRD measurement, it was shown that the single-phase layered compound can be prepared in sintering temperature of 750℃ for 6~8 hours. The sintering temperature, the properties and the amounts of doping materials can all affect the product's phase, and its structure (lattice parameter, crystal phase distance).2 Study on the synthesis and properties of LiNiO2 doped with Co elementsTo improve the crystal structure and cycling performance of LiNiO2 . we doped with Co, and studied the influence of it's amount on the crystal structureand electrochemical properties of LiNiO2. Experimental results showed that the first discharge capacity of LiNio.75Coo.25O2 is 183.6 mAh/g at the current of 1 mA/g and voltage between 3.00 and 4.50V; after 50 cycles, its discharge capacity is 152.6 mAh/g. these results show that it has good electrochemical properties and promises a hopeful cathode material for lithium-ion battery. 3 study on the synthesis and properties of LiNiO2 doped with multi-elementsOn the basis of LiNixCo1-xO2, other elements M(M=A1, Mg, Mn or Ti)were further doped in LiNixCo1-xO2. the ions of multi-element dopants exert cooperative effects on the crystal structure of LiNiO2and improve the comprehensive performance of LiNiO2...