| Summary: | 碩士 === 東海大學 === 化學工程學系 === 94 === The precursor of CoO (α-Co(OH)2) was prepared by the electrodeposition with various strring rates, nano-particles with different amounts and particle sizes in the presence of surfactant triton X-100 or not. Cobalt oxide (CoO) was obtained by calcinations of α-Co(OH)2 in N2 atmosphere at 500 oC. Furthermore, Ni was sputtered on CoO surface to prepared CoO-Ni/Cu in this thesis. The charge/discharge properties of CoO prepared in this work were investigated by the coin cell of Li/1.0M LiPF6 , EC-DEC (v/v=1:1) / CoO in the potential range of 0.02~3V. The characteristics of CoO were analyzed by SEM, XRD, FTIR and EDS, respectively.
The morphology of α-Co(OH)2 analyzed by SEM were nano-fiber type structures. The properties of CoO and its precursor were affected by the stirring rate, the amount and size of SiO2 and TiO2 nano-particles, and surfactant for electrodeposition of the precursor. Whenα-Co(OH)2was prepared in pH 3.30~3.14 and 50 rpm, the grain size of CoO was found to be 31~27 nm, the grain size of CoO was decreased to 16~12 nm by addition of 0.05% 12nm SiO2 for preparing α-Co(OH)2. By further adding 0.065M triton X-100 to prepare the precursor of α-Co(OH)2 in the electrodeposition, the grain size was decreased to 14~11 nm.
When the precursor was prepared in pH 3.30~3.14, the thickness, the irreversible capacity in the first cycle and the maximum charge capacity of CoO film decreased from 2.5~3.0μm and 29.9 % to 2.0~2.4 μm and 24.3 %, and the maximum charge capacity increased from 1580 to 3321 mAh g-1 with the increase in the stirring rate from 50 to 100 rpm for preparingα-Co(OH)2.
The maximum capacity of CoO (thin film)/Cu was obtained to be 1580 and 2471 mAh g-1 at the charge/discharge cycle of 30 and 69 for preparing the precursor of CoO in the absence and presence of 0.05% 12nm SiO2. The functions of SiO2 in the CoO were deduced to be acted as the support of Co to catalyze the formation/dissolution of the polymeric gel. Moreover, the CoO grain size in the calcination procedure, and the Co particle size in the charge/discharge process were restricted by the presence of the SiO2 nano-particle Hence the charge/discharge capacity of CoO was effectively promoted, and the capacity fading was inhibited by the presence of SiO2 nano-particle. The increase in the capacity and decrease in the capacity fading were also obtained by sputtering Ni on the CoO surface due to the increase in the conductivity of CoO electrode.
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