新型固態電解質之合成與性質探討; New Polymer Electrolyte for Lithium battery Based on PEO-PAN-LiClO4 System

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题名:	新型固態電解質之合成與性質探討;New Polymer Electrolyte for Lithium battery Based on PEO-PAN-LiClO4 System
作者:	吳炯輝;Chiung-Hui Wu
贡献者:	化學研究所
关键词:	鋰高分子二次電池;Secondly Lithium battery
日期:	2003-07-04
上传时间:	2009-09-22 10:11:22 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	摘要隨著3C電子的輕薄短小化，攜帶式能源的需求與日俱增，由於鋰二次電池具有優於傳統電池的各項特性如：具備高工作電壓、工作電壓平穩、循環壽命長、自放電率低、使用溫度範圍廣、且無記憶效應等優點而廣受重視。鋰二次電池包含了鋰離子電池與鋰高分子電池，而真正要達到輕薄短小化之目標，必須將電池內之電解質以固態的形式取代液態或膠態，使電子產品可不受形狀與尺寸大小等之限制，所以離子導電性高之固態電解質不但能開發新型攜帶式能源，且也是使電子產品邁向新紀元的重要關鍵。本研究以PEO- LiClO4作為固態電解質之主體，將不同比率的PAN加入製成混摻高分子電解質，並在不同溫度下加熱將PAN交連以尋求最佳固態電解質材料。我們以離子導電度測量儀、DSC、XRD、TGA、固態7Li NMR及SEM來探討其物性，成功研究出以微量PAN(1wt%?3wt%)摻雜之LiClO4(15wt%)-PEO為最佳之混成比例，由TGA可知此系統之高分子膜熱穩定性皆可達350℃以上。離子導電度在50℃時可達6.8x10-4 S/cm，由於PAN加熱後會自身環化，利用此特性做高分子電解質之加熱並快速冷卻處理，DSC所得到之結果可知PAN會阻擾PEO結晶，可更進一步破壞PEO之結晶度而提升其離子導電度，且由SEM發現高分子薄膜表面變得更加平整，為固態電解質提升離子導電度之研究提供一新的方向。 Abstract Since 1975 Wright et al. discovered the ionic conductivity (1x10-7 S/cm) of PEO-Lithium salt, PEO-Lthium salt based solid electrolytes have under extensively studied. However, the room temperature conductivities of PEO-Li salts are usually too low (due to the semi-crystalline nature of PEO) to be applied practically in lithium batteries. Therefore, increasing the conductivity via various physical or chemical methods has become the major research efforts. To enhance the conductivity of PEO-LiClO4 system, one of the good strategies was forming polymer blend. In this thesis, we blended the precursor of conjugated polymer PAN (polyacrylonitrile) (with PAN/PEO ratios equal to 0wt%, 1wt%, 3wty%, 5wt%) into the PEO-LiClO4 system (and/or heat the blend polymer to crosslink the PAN) to increase the conductivity and film dimension stability. It was found that by adding 1wt% PAN into PEO-LiClO4(15wt%) the hybrid polymer electrolyte has the highest ionic conductivity (up to 6.8x10-4 S/cm at 50oC) and exhibit good mechanical properties. Heating the polymer blends up to 200oC can further increase their conductivity. XRD data showed that the domain size of PEO-LiClO4-PAN is smaller than that of PEO-LiClO4. DSC results also indicated that both the melting point and crystalinility of PEO-LiClO4(15wt%) decreased after adding PAN. The crystallinity of PAN- PEO-LiClO4(15wt%) decreased further after rapidly heating and cooling of the electrolyte films. SEM micrographs showed that when small amount of PAN (PAN/PEO <5wt%) was added, the electrolyte films have a smoother surface compared to pure PEO-LiClO4. The function of PAN can be regarded as a polymer support for dispersing PEO matrix and increase the dimension stability when the crystallinity of PEO decreased.
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