Li1+xCoyMn2-x-yO4的结构及电化学性能研究

利用溶液相合成技术把钴掺入到主尖晶石相中制得掺钴尖晶石相材料.所合成的材料具有颗粒分布均匀及结晶性能好等特点.利用X射线粉末衍射仪、傅里叶变换红外分光光度计及扫描电子显微镜对所合成掺杂锂材料的结构性能进行表征.研究表明掺杂钴可提高材料的结构稳定性能,减少锰在电解液中溶解,减少锂离子在材料中迁移电阻.电化学性能测试结果表明所合成掺钴材料Li_1.03Co_0.05Mn_1.92O₄具有较好的初始容量及循环稳定性能.

Structural Characteristics and Electrochemical Properties of Co-doped Spinel Li1+xCoyMn2-x-yO4 for Lithium-ion Batteries

Cobalt was doped into the host spinel to produce cobalt-doped spinel material by a solution technique. The end Co-doped materials have many advantages of narrowly distributed and well crystallized particles and small surface area. The determination of XRD patterns shows that the peaks shift towards high angle and become sharp as the introduction of cobalt. The analysis of infrared (IR) spectroscopy illustrates that cobalt doping can enhance the strength of Mn--O bonds and improve the structural stability of the materials. The presence of cobalt reduces the dissolution of Mn into the electrolyte according to the investigation of ICP analysis results since Co-doped materials have more stable structure and smaller surface area. Cobalt doping can enhance the bond Mn--O and weaken the bond Li--O in the spinel. As the result, the Li⁺ ion has easier diffusion in the spinel and the Co-doped material has smaller charge-transfer resistant (R_ct). The measurement of electorchemical properties shows that the Co-doped material Li₁.₀₃Co_0.05Mn_1.92O₄ prepared in this technique has good cycling performance and high initial capacity.