掺镍型层状Li_xNi_yMn_(1-y)O_2正极材料的合成与电性能研究

Studies on the Layered Li_xNi_yMn_(1-y)O_2 Cathode Material: Synthesis,Structure and Electrochemical Properties

A kind of cathode material of layered LixNiyMn1- yO2 characterized with the O2 type has been synthesized by a simple method. Its precursor NaxNiyMn1- yO2 has been prepared from manganese dioxide, nickel hydroxide and sodium carbonate at high temperature in air and quickly cooled in cold water, then it has been exchanged by the melted LiNO3 at 300～ 400℃ in air. The effects of calcine temperature for the precursors and its compositions (the content of Na and Ni) on the electrochemical properties of the material LixNiyMn1- yO2 have been investingated by XRD and electrochemical tests. The results show that the sample Li0.7Ni0.3Mn0.7O2, has the best electrochemical properties which shows only one charge discharge potential stage of 2.8～ 3.0V and has a high specific capacity over 180mAh· g- 1 cycled between 2.0～ 4.20V. A significant structure transformation to the spinal type phase has not been found in the charge discharge cycling and the discharge specific capacity around 165mAh· g- 1 has remained after the 20th cyclings for the material.

A kind of cathode material of layered LixNiyMn1-yO2 characterized with the O-2 type has been synthesized by a simple method. Its precursor NaxNiyMn1-yO2 has been prepared from manganese dioxide, nickel hydroxide and sodium carbonate at high temperature in air and quickly cooled in cold water, then it has been exchanged by the melted LiNO3 at 300 similar to 400degreesC in air. The effects of calcine-temperature for the precursors and its compositions the content of Na and NO on the electrochemical properties of the material LixNiyMn1-yO2 have been investingated by XRD and electrochemical tests. The results show that the sample Li0.7Ni0.3Mn0.7O2, has the best electrochemical properties which shows only one charge-discharge potential stage of 2.8 similar to 3.0 V and has a high specific capacity over 180mAh (.) g(-1) cycled between 2.0 similar to 4.20V. A significant structure transformation to the spinal-type phase has not been found in the charge-discharge cycling and the discharge specific capacity around 165mAh (.) g(-1) has remained after the 20th cyclings for the material.