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Preparation of graphite-like carbonaceous thin films by plasma CVD

等离子体CVD法制备类石墨碳质薄膜

基本信息

批准号：
11555238
负责人：
OGUMI Zempachi
金额：
$ 8.64万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555238/
关键词：
carbonaceous thin film plasma lithium secondary batteries diffusion

项目摘要

Lithium ion batteries have been vastly studied for use of portable electric devices. Recently, the batteries are expected to be power sources of hybrid electric vehicles. Carbonaceous materials have been used as negative electrodes in lithium ion batteries, and various carbonaceous materials have been investigated to improve the battery performances of lithium batteries. To elucidate the precise electrochemical properties of carbonaceous materials, thin film electrodes are very ideal, and therefore, we fabricated the very flat and homogeneous carbonaceous thin film electrode by means of plasma assisted CVD. Followings are the results obtained :(1) Carbonaceous thin films with low to high crystallinity have been obtained by plasma CVD at lower temperatures below 1023 K.(2) Diffusion coefficients of resultant carbonaceous thin film electrodes are evaluated, and the values first increased with increasing lithium ion content in carbonaceous and then decreased.(3) Lithium ion transfer at interface between electrode and electrolyte has been studied by AC impedance spectroscopy, and the activation energies for the lithium ion transfer at interface were determined. As a result, the activation energies were dependent on the electron donicity of solvents in electrolytes.(4) Surface modification of carbonaceous thin film electrodes were made in NF_3/Ar plasma, and the electrochemical properties of the surface-treated thin film electrodes was studied. The first irreversible capacities were greatly reduced as compared with those of no surface-treated carbonaceous thin films.

锂离子电池在便携式电子设备中的应用已被广泛研究。最近，这种电池有望成为混合动力汽车的动力源。碳素材料已被用作锂离子电池的负极，为了提高锂离子电池的电池性能，人们对各种碳素材料进行了研究。为了阐明碳材料的精确电化学性质，薄膜电极是非常理想的，因此，我们利用等离子体辅助化学气相沉积的方法制备了非常平坦、均匀的碳薄膜电极。结果表明：(1)在低于1023K的较低温度下，等离子体CVD法制备了结晶度由低到高的碳质薄膜；(2)计算了碳薄膜电极的扩散系数，其值随碳中锂离子含量的增加先增大后减小。(3)用交流阻抗谱研究了锂离子在电极-电解液界面上的迁移，确定了锂离子在界面上迁移的活化能。在NF3/Ar等离子体中对碳质薄膜电极进行了表面修饰，并研究了表面处理后的薄膜电极的电化学性质。与未经表面处理的碳质薄膜相比，薄膜的第一不可逆容量大大降低。