The effects of nickel hydroxide with different cobalt contents on the electrochemical performance for Ni-MH batteries
Date Issued
2004
Date
2004
Author(s)
Chang, Chia-Wen
DOI
zh-TW
Abstract
本實驗採用水溶液法之一的「化學共沉澱法」合成奈米結構氫氧化鎳粉末，並掺雜3wt%鋅及不同含量的鈷以抑制電極膨脹及增加電極的導電度。在所有添加物以鈷之添加對Ni(OH)2正極電化學性能之增進最為明顯，因此本研究著重於鈷添加於Ni(OH)2正極所扮演的角色，進而找出一最佳之添加比例。
利用粒徑分析儀、X光粉末繞射儀(XRD)、掃描式電子顯微鏡(SEM)、穿透式電子顯微鏡(TEM)及感應耦合電漿質譜分析儀(ICP)對各個Ni(OH)2樣品進行物性及化性的測試。並使用實驗室的充放電儀及恆電位/恆電流儀從事充放電及交流阻抗測試。
實驗結果顯示各個Ni(OH)2樣品粒徑分佈範圍為6.0~6.9µm，而且所有樣品所呈現的XRD圖形皆為β-Ni(OH)2特性峰，代表添加鈷含量的多寡，對於Ni(OH)2的物性並無太大的影響。進而比較不同鈷添加量之Ni(OH)2正極在電池性能上的差異，本實驗以添加6wt%Co之電極，電容量為265.2mAh/g，活性物質利用率為91.8%，為最大值。
In this work, nano-structured nickel hydroxide powder was synthesized with 3wt% Zn and different Co contents by a chemical co-precipitation process. Cobalt increases remarkably the active-material utilization through enhancement of the discharge depth due to the formation of conducting CoOOH during charging. The effect on the electrochemical behavior of different amounts of cobalt addition to the nickel hydroxide is investigated.
The physical properties of several nickel hydroxide powders containing different amounts of cobalt are examined by laser diffraction, X-ray diffraction, scanning electron microscopy, transfer electron microscopy and inductively coupled spectroscopy measurements.
The particle sizes with the irregular shape range from 6.0 to 6.9 µm through laser diffraction. The samples exhibit β-phase Ni (OH) 2 through X-ray diffraction analysis. The maximum discharge capacity of 265.2mAh/g is obtained for nickel hydroxide prepared with 6wt% cobalt addition. Moreover, the charge and discharge potentials of nickel hydroxide samples decrease with increase in cobalt content. The nickel hydroxide electrode doped by cobalt has shown lower charge transfer resistance and higher electronic and photonic conductivity.
Subjects
氫氧化鎳
鈷添加物
電化學性能
nickel hydroxide
cobalt addition
electrochemical
Type
thesis
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