Li(AlxCo1-x)O2晶体中Co3+电子态的变化及对结构演化的影响

研究了应用于锂二次电池正极的新型高能量密度存贮材料Li(AlxCo1-x)O2 (x=01—05)的磁性.发现Al3+的掺杂可导致Co3+中d电子自旋态发生变化，即有部分d电子进入高自旋态.伴随Co3+中电子状态的改变，材料结构演化也发生了相应变化，表现为c/a比增大明显减缓，较好地解释了材料结构对Vegard定律的正偏离.这对材料的微观结构与性能设计具有重要意义. 关键词： 锂电池材料 Li（AlxCo1-x）O2 磁性 自旋态 结构演化

Transformation of electronic state of Co3+ and its influence on the structural development in Li(AlxCo1-x)O2

In this paper we have studied the magnetism of a new cathode material with a high energy density, Li(AlxCo1-x)O2(x=01—05), which is used in rechargeable lithium batteries. We found that doping Al can change the spin state of d electron in Co3+， leading to the emergence of high spin d electrons. Accompanied with this, there are also some changes of the structure development which is indicated by the obviously decreasing rate of the increasing value of c/a. This explains the positive deviation of the structure from the Vegard law. This is very important to the design of the microstructure and properties of materials.