鋰錳氧正極材料之表面活性劑對電化學性能的影響

Effect of surfactant on the electrochemical properties of LiMn2O4 cathode material for Lithium-ion battery

蘇湘茹(Hsiang-Ju Su)

指導教授 ： 楊永欽

國立臺北科技大學/工程學院/材料及資源工程系研究所/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00706

摘要

本實驗主要是利用固相反應法(solid state reaction method)的製程技術，並利用中性界面活性劑及三區塊共聚高分子P123為模板，在酒精溶劑裡形成有機物自組裝體，而以LiCH3COO•2H2O及Mn(CH3COO)2•4H2O作為無機物骨架的前驅物，來合成出尖晶石(Spinel)結構的 LiMn2O4 材料，探討界面活性劑含量的不同，對於粉體的結構、顆粒大小、表面積改變，而材料表面積大小會影響到電解質與正極材料之濕潤結果，進而影響到實際反應面積及放電效率，進而探討表面積對於電性影響。
由XRD分析得知，以固相反應法合成出的LiMn2O4為單一尖晶石相，添加界面活性劑並不會影響原本尖晶石結構，藉由BET分析結果得知，隨著界面活性劑量的增加，比表面積也隨之改變，在SEM的觀察下，顯示出LiMn2O4在添加不同界面活性劑後可形成不同形狀的微胞，微胞有助於電容量的增加。實驗顯示比表面積在0.4 ~ 1.2 m2/g，較能有效提升電容量且大電流放電效率較接近低電流放電效率，電容量最高可達84.6 mAh/g，依照不同濃度之P123，以1.42M之鋰離子擴散係數為6.23x10-12 cm2•s-1，且比表面積為1.18 m2/g，在不同速率充放電下，大電流放電與低電流放電接近。相較於不同濃度之F127，以3.43M之Li+ 離子擴散係數1.37x10-11 cm2•s-1為最佳，其比表面積為0.70 m2/g，雖電容量最高，但在大電流放電時較易衰退。實驗結果顯示以P123體積莫耳濃度為1.42M較佳。

關鍵字

固相反應法 ； LiMn2O4 ； 尖晶石

並列摘要

The purpose of this reserch will try to fabricate the LiMn2O4 with ordered spinel structure. The three block copolymer surfactant(P123)was employ as the structure agents for synthesizing the high specific surface area in LiMn2O4 through the solid state reaction method. The LiCH3COO•2H2O and Mn(CH3COO)2•4H2O are as the precursors for the inorganic part of cathode (LiMn2O4). Discuss the different content of surfactant with the structure of the powder particle size, specific surface area, while the material specific surface area will affect the moist results of the electrolyte and cathode material, so affecting the actual reaction area and discharging efficiency. That investigating the affection between specific surface area and electrical attributes.
According to XRD patterns, the solid state reaction method synthesis of LiMn2O4 is a single spinel phase. By BET analysis results indicated that adding a surfactant doesn’t affect the original spinel structure. In the SEM observations, after different surfactants are added in LiMn2O4, that become various formation of micelles and micelles contribute to the increase of specific capacity. By this reserch, specific surface area in 0.4 ~ 1.2 m2/g compared with the capacitance can effectively enhance the efficiency and high current efficiency of discharge is closer to the lower current discharge. And the specific capacity can up to 84.6 mAh/g, in accordance with different concentrations of P123 surfactant 1.42M that the Li+ ion diffusion coefficient is 6.23x10-12 cm2 s-1, and specific surface area of 1.18 m2/g. Under the different rates of charging and discharging, the higher will close to lower. However compared with different concentrations of F127 surfactant 3.43M of the Li+ ion diffusion coefficient of 1.37x10-11 cm2s-1 is the best, the specific surface area of 0.70 m2/g. Although the maximum specific capacity, but higher than in the high-current discharge easy recession. The experimental results show that the better to add P123 surfactant 1.42M because the high current efficiency of discharge is closer to the lower current discharge.

並列關鍵字

LiMn2O4 ； spinel ； solid state reaction method

參考文獻

參考文獻

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