鋰離子電池LiNi1/3Co1/3Mn1/3O2陰極材料之製程開發與改質研究

Synthesis and surface treatment of LiNi1/3Co1/3Mn1/3O2 cathode materials for Li-ion batteries

張忠勝(Chung-Sheng Chang)

指導教授 ： 費定國

國立中央大學/工學院/化學工程與材料工程學系/碩士(2007年)

摘要

於本論文中，為達到縮短製程時間、減少合成費用，並製備高性能之LiNi1/3Co1/3Mn1/3O2 陰極材料，吾人分別以溶液燃燒法和微波處理法進行此材料之製程開發，經由改變各重要合成變因，尋找最佳製程條件。隨後，以機械式熱處理法，嘗試利用不同氧化物，將兩方法最佳製程的陰極材料進行塗佈改質，期能改善材料於高充電電壓下之循環穩定性，並提升其熱安定性與承受高速率充放電的總體能力。

經研究後顯示，吾人所開發的溶液燃燒法和微波處理法，皆僅需傳統共沉澱合成法的三分之ㄧ製程時間，即可獲得品質良好與性能優異的LiNi1/3Co1/3Mn1/3O2 陰極材料。於充放電截止電壓分別為4.6 與2.5 V，充放電速率為0.2 C-rate 的測試條件下，溶液燃燒法與微波處理法之最佳製程陰極材料，可分別獲得179 mAh/g 與184mAh/g 的初始放電電容量。此外，利用不同氧化物，以機械式熱處理法進行表面改質後得知，經由0.50與0.25 wt.% Al2O3 塗佈後，溶液燃燒法與微波處理法所製備之材料可分別由改質前的47 與30 次充放電循環，大幅提升至97 與50 次之多，說明材料經由Al2O3 的塗佈後，藉由Al2O3 緊密包覆於材料外圍，減少電活性物質與電解質液的直接接觸，進而提升了陰極材料之循環穩定性。

相較於傳統共沉澱合成法，吾人以溶液燃燒法和微波處理法，進行LiNi1/3Co1/3Mn1/3O2 之材料製備，兩方法不僅具備快速、方便與經濟的特點，溶液燃燒法與微波處理法更分別具有製程簡單與反應快速之絕對優勢。在未來如此分秒必爭的年代，吾人所開發之製備方式，不僅大幅縮減了製程時間與人物力生產投資成本，亦提高了能源材料於市場應用的絕對競爭力。溶液燃燒法和微波處理法，的確更適用於大量的工業量產上，亦可視為相當具潛力的陰極材料製備方法。

關鍵字

陰極材料 ； 塗佈改質 ； LiNi1/3Co1/3Mn1/3O2 ； 鋰離子電池

並列摘要

In order to shorten process time, reduce synthesis cost, and prepare high performance cathode materials, layered LiNi1/3Mn1/3Co1/3O2 powders were synthesized by two methods, respectively, one is the solution combustion process with hexamethylenetetramine as a fuel and the other is the microwave method followed by short duration high temperature calcination.

After determining optimal preparation conditions, cathode materials synthesized under these conditions and surface treated separately with different metal oxides to enhance cycle stability using a simple mechano-thermal coating procedure.

The powders prepared by solution combustion and microwave methods generated a discharge capacity of 179 mAh/g and 183 mAh/g, respectively, at a 0.2 C-rate between 4.6 and 2.5 V in the first cycle. The structure and morphology of the bare and the surface modified LiNi1/3Mn1/3Co1/3O2 samples have been characterized with XRD, FE-SEM, DLS, TEM, EDS, and DSC techniques.

Electrochemical studies revealed that both methods needed only a third of the process time to synthesize a LiNi1/3Mn1/3Co1/3O2 cathode compared to a conventional co-precipitation route. After surface modification, all the
LiNi1/3Mn1/3Co1/3O2 powders coated with Al2O3 have showed improved cyclabiliy, indicating that coating materials can stabilize the cathode structure by suppressing characteristic structural phase transitions. Moreover, the
mechano-thermal coating process is a simple, inexpensive, environmentally benign and commercially viable for producing high-cycling LiNi1/3Mn1/3Co1/3O2 cathode materials.

並列關鍵字

surface coating ； cathode ； Lithium-ion battery ； LiNi1/3Co1/3Mn1/3O2

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