為提升固態電解質應用在鋰電池中的各項性能，如導電度、充放電表現與介面相容性等等的性質，許多研究指出在聚合物電解質中加入無機物可有效提升導電性、介面相容性，並且降低高分子的結晶性以提升高分子的鏈段移動率。但無機物添加過多時將在電解質中產生聚集的現象，降低無機物表面積，與鋰鹽或離子液體、高分子的作用力較差而損傷其功效，因此藉由官能基化使無機物能夠高度均勻分散成為目前重要的研究方向。 本實驗研究以PVdF-HFP與PMMA為高分子主體，加入離子液體作為塑化劑及液體電解質之替代品，再以官能基化後的TiO2-PMMA為填充物，可有效提升導電度與介面相容性。作為官能基的PMMA則可提升與高分子基材的相容性以及介面穩定性，此外，官能基化帶來的效果是防止TiO2嚴重聚集，在系統中可添加更多的TiO2來提升各項性質。本實驗探討了官能基化無機物對電解質中離子傳導的機制與製作成半電池後的電性表現。此方法製作出的電解質在室溫下具有最高的導電度為2.71×10-3 S/cm，以0.1C充放電得到的放電電容最高達到150 mAh/g。也說明本研究製作的官能基化無機物電產生一款具有絕佳安全性與導電度的新穎固態電解質，可望能應用在大規模化工業生產的固態電池上。 ;Polymer electrolytes (PEs) offer several advantages over concentional electrolytes. For example: it improves safety (relative to commercial electrolytes), shows good mechanical stability; thermal stability and higher energy density. But their low room temperature ionic conductivity limits their wider application in advanced batteries. Incooperating inorganic nanofillers in PEs is an effective means to improve ion conductivity and reduce interfacial stability. However, high surface energies of nanoparticles tends to aggregate and cluster easily which lowers the surface area. Aggregation of nanoparticles may block the ion transport pathway in polymer matrix. Surface modification on nanoparticles ia an effective approach to avoid aggregation, and proper choice of the functional groups can induce better miscibility between the particle and the base polymer leading to enhanced property advantageous for solid state lithium batteries. Here, we successfully prepared the funtionallized-TiO2 (FTiO2) by surface modification of PMMA on TiO2 nanoparticle. We then incooperate FTiO2 in PVdF-HFP/PMMA system with ionic liquid (EMIMTFSI) as the plasticizer. PMMA on TiO2 surface provide good compatibility with polymer matrix and adhesion property with electrode,where the interface resistance is substantially reduced. The FTiO2 composite polymer electrolyte (CPE) exhibit fair ion conductivity at 20℃ (2.71×10-3 S/cm) with improved interfacial resistance. Lithium battery half cells using FTiO2 CPE with LiFePO4 as cathode, show durable cyclic capacity at 150 mAh/g at 0.1C-rate. The result suggested the novel polymer electrolyte by incorporating surface functionalized TiO2 and the use of ionic liquid as the plastizer demonstrated superb ionic conductivity and low interface resistance, and is highly promising to be used in next generation all solid state lithium battery.
