吳乃立臺灣大學：化學工程學研究所張顥薰Chang, Hao-HsunHao-HsunChang2007-11-262018-06-282007-11-262018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/52146因鋰鐵磷酸鹽 LiFePO4 具有成本低廉、穩定度高等等特性，且所含元素皆為環境友善之物質，所以被認為是極有潛力之鋰離子正極材料。本論文的研究範圍在於從事高導電度奈米 LiFePO4/carbon black 複合正極材料之合成。 論文中的實驗部分以二種方法來合成 LiFePO4/carbon black ，分別是固相法和液相法。文中關於合成條件的主要探討分成氣氛之選擇、定量分析求轉化率、轉化率的影響因素、晶粒尺寸的比較與趨勢、及二合成方法間的比較。 在氣氛的選擇方面，由實驗結果以 1% H2（99%N2） 為佳，過多或過少皆會有多量雜質的產生。而經分析，發現在各燒結溫度下，轉化率在很短的燒結時間內立刻分別趨於各自的固定值，即使燒結持溫時間繼續拉長，亦無助於轉化率的提高，意為影響轉化率的因素主要是燒結溫度，而不是燒結時間。但是晶粒尺寸則受到燒結時間的延長而有增大的趨勢。製得的粉體也用掃瞄式電子顯微鏡加以觀察，以 固相法所製得之粉體呈現以微米級晶粒團聚而成的團塊，而液相法所得之粉體上則有緊密的碳黑附著。經由種種詳細的條件比較及批量製程考量，合成方法中以「液相法」效果最佳，在700℃以下可獲得小於100nm之奈米晶粒。 本論文還對LiFePO4的合成反應進行非定溫動力學分析，結果顯示其反應限制機制為nuclei growth。 在電化學測試方面使用循環伏安法及充放電儀來進行測試。其結果顯示，若在 1C-1C 的充放電條件之下，液相法所得的LFPO展現出約 85mAh/g 的電容量，在0.1C-0.1C時則可達110mAh/g。Compared with the oxide electrode materials currently used for the lithium ion battery, LiFePO4 has the advantages of lower cost, high stability, and environmentally friendly. Hence, it is considered as a good candidate of positive electrode material. The thesis is mainly on the synthesis of composite positive electrode material of nano LiFePO4/carbon black with high conductivity. In this report, nano LiFePO4/carbon black is synthesized through solid state method and liquid phase method. The investigation agenda of the synthesis conditions include the selection of atmosphere, conversion via quantitative analysis, the effecting factors of conversion, tendency of crystal size, and the comparison. On choosing reaction atmosphere, the experimental data indicate that the best one is that with 1%H2（99%N2）, whereas impurity is incurred with excess or insufficient gas. Through analysis, it is found that the conversion of each approach quickly arrives to its own constant value under various sintering temperatures. It has no effect for improving the conversion even prolonging the sintering time. It implies that the principal factor affecting the conversion rate is the sintering temperature rather than the sintering time. Nevertheless, the crystal size tends to agglomerate with the sintering time. A scanning electron microscope (SEM) is used to examine the synthesized powder. Powder made by the solid-state method shows aggregates of micro-scale crystals, whereas powder of liquid phase approach is tightly adhered by carbon black. From comparison of meticulous conditions, as well as the survey of batch-wise preparations, it is concluded that the “liquid phase approach” is the better choice of the two methods. It can provide nano crystals of less than 100nm under 700℃. Moreover, the thesis presents a non-isothermal kinetic analysis of the synthesis of LiFePO4, where three dimensional nuclei growth is found to be the reaction limiting mechanism. Cyclic voltametry and charge-discharge cycle test was applied to perform the electrochemical test. In the result, LFPO via liquid method revealed capacity of 85mAh/g at C-rate 1C-1C, and 110mAh/g at 0.1C-0.1C.本　文　目　錄 摘要 I 本文目錄 V 圖表目錄 VII 第一章 緒論 1 第二章 文獻回顧 3 2-1 鋰離子二次電池正極材料 3 2-2鋰鐵磷酸鹽複合材料 8 2-3 熱分析在動力學上之應用 14 第三章 實驗部分 21 3-1 固相法 21 3-2 液相法 21 3-3 臨場 X-ray Diffraction 24 第四章 結果與討論 27 4-1氣氛的選擇 27 4-2晶粒尺寸的計算 29 4-3壓錠壓力的影響 30 4-4定量方法與轉化率的求得 31 4-5溫度對轉化率的影響 31 4-6轉化率與再混合 37 4-7改變升溫速率 39 4-8轉化率的比較與晶粒大小 45 4-9非等溫動力學分析 46 4-10以SEM觀察LFPO 59 4-11電化學性質分析 62 第五章 結論與建議 68 第六章 參考文獻 70 圖　表1583596 bytesapplication/pdfen-US動力學製備鋰鐵磷酸鹽正極材料鋰離子電池Cathode materialLiFePO4Lithium-ion batteryKinetics[SDGs]SDG7thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/52146/1/ntu-93-R91524087-1.pdf