商業上對於電池能量密度的要求越來越高，因此越來越多新興材料的研究蓬勃發展。在正極材料上面，富鋰層狀材料是其中一種極具潛力的材料，由於本實驗所得到的充放電循環圖異於典型的富鋰正極材料之表現，因此本實驗首先在製程上透過不同的退火溫度利用SEM、XRD、TEM、XPS、RAMAN分析含鋰、鎳、錳、氧的富鋰層狀材料，觀測其在不同退火溫度下的相、雜質生成對於其電性及電化學表現的影響。
　　為了克服富鋰層狀材料在電池充放電時所會面臨的相變化問題，本實驗接著分別透過尖晶石表面改質以及碳酸鹽表面改質來觀測分別加上兩種材料的塗層後，電池的循環表現是否會有變化。以目前所得到的數據來說，兩者都能改善原先樣品不尋常的充放電曲線，其中，又以碳酸鹽表面改質在前60圈的循環中有比較好的比電容量。

Lithium-rich cathode material is one of the most potential cathode material for lithium ion battery due to its high specific capacity and high voltage compares to other cathode materials. However, as the charge and discharge cycle goes on, phase transition will happen in this material and the original layered structure will transform to spinel structure, which makes the capacity decreasing. As a result, figuring out mechanisms of phase transition and finding a way to prevent phase transition is very critical. In the first part of this thesis, we discuss the influences of different phases, and formation of impurities on electrochemical performance under different annealing temperature. In the second part of this thesis, we use precipitation methods to coat spinel and carbonate materials on our lithium-rich cathode material. For the carbonate-coating sample, the charge retention after 60 cycles is estimated to be 82%. This result shows that the carbonate-coating method could prevent phase transition and promote the battery efficiency.

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