LiCoO2 Cathode Material That Does Not Show a Phase Transition from Hexagonal to Monoclinic Phase
LiCoO2 Cathode Material That Does Not Show a Phase Transition from Hexagonal to Monoclinic Phase
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DOI：
10.1149/1.1397772
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发表时间：
2001-10
影响因子：
3.9
通讯作者：
Jaephil Cho;Y. J. Kim;Byungwoo Park
中科院分区：
文献类型：
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作者：
Jaephil Cho;Y. J. Kim;Byungwoo Park
采用溶胶-凝胶法包覆Al 2 O3并进行热处理可以改善LiCoO 2的结构不稳定性。热处理后，颗粒内部没有Al 2 O3相存在，但在表面形成了Al浓度较高的固溶体LiCo 1-xAlxO 2。然而，热处理至700°C导致固溶体的存在超过500 A。在表面处的不同Al浓度显著地影响材料在循环期间的结构稳定性，并且在400°C下制备的那些没有显示出从六方相到单斜相的相变。这种相变的消失改善了阴极的容量保持率。此外，在400 ° C和500°C下制备的阴极显示出具有阳离子顺序的改进的分层特性。
Structural instability of LiCoO 2 can be improved by sol-gel coating of Al 2 O 3 and subsequent heat-treatments. While Al 2 O 3 phase does not exist after heat-treatments, solid solution LiCo 1-x Al x O 2 that has discretely higher Al concentration was formed at the surface up to ∼500 A inside the particle. However, heat-treatment to 700°C results in the presence of the solid solution beyond ∼500 A. The different Al concentration at the surface significantly affects the structural stability of the materials during cycling, and those prepared at 400°C do not show a phase transition from hexagonal to monoclinic phase. Disappearance of such a phase transition improves capacity retention of the cathode. Moreover, cathodes prepared at 400 and 500°C show improved layered characteristics with cation order.