Effect of post-deposition annealing in oxygen atmosphere on LiCoMnO4 thin films for 5 V lithium batteries
Effect of post-deposition annealing in oxygen atmosphere on LiCoMnO4 thin films for 5 V lithium batteries
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DOI：
10.1016/j.tsf.2019.137433
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发表时间：
2019-09-30
期刊：
影响因子：
2.1
通讯作者：
Kawamura, Junichi
中科院分区：
文献类型：
--
作者：
Ishigaki, Norikazu;Kuwata, Naoaki;Kawamura, Junichi
薄膜电池是未来微型器件一种有前景的微型高容量能源。提高能量密度的一种可能方法是使用由尖晶石LiCoMnO₄制成的阴极，其理论比能量为475瓦时/千克，工作电压约为5伏。然而，这种材料的一个问题是在薄膜形成过程中晶格中的氧损失，这导致在5伏时容量损失以及在约4伏处出现意外的峰值。在此处报道的研究中，通过在不同温度和不同时间段下在氧气流中对薄膜进行沉积后退火，研究了氧损失对薄膜电池性能的影响。通过X射线衍射（XRD）峰的强度及其位置偏移来表征结晶度和氧缺陷。在放电容量和XRD峰偏移（或薄膜的氧含量）之间发现了明显的相关性。基于这些结果，确定LiCoMnO₄薄膜沉积后退火的最佳条件组合是在氧气气氛下600℃持续6小时。
Thin-film batteries are a promising microscale high-capacity energy sources for future micro devices. One possible way to increase the energy density is to use a cathode made of spinel LiCoMnO4, which has a theoretical specific energy of 475 Wh/kg and operates at about 5 V. However, one problem of this material is the loss of oxygen in the lattice during the thin-film formation process, which causes the loss of capacity at 5 V and the appearance of unexpected peak at around 4 V. In the study reported here, the effect of oxygen loss on the thin-film battery performance was investigated using post-deposition annealing of the thin-films under an oxygen flow at different temperatures and for different periods of time. The crystallinity and oxygen deficiency were characterized by the intensity of the X-ray diffraction (XRD) peaks and their shift in position. A clear correlation was found between the discharge capacity and the XRD peak shift (or oxygen content of the thin films). Based on these results, the optimum combination of conditions for post-deposition annealing of the LiCoMnO4 thin films was determined to be a temperature of 600 degrees C for 6 h under an oxygen atmosphere.