POLYMER ELECTROLYTE MEMBRANES PREPARED BY BLENDING CHITOSAN AND IONIC LIQUID (EMImBF4)/Li+ FOR LITHIUM-ION BATTERIES APPLICATION

• Main Author: Horale Pasaribu, Marvin
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/32340
• Institution: Institut Teknologi Bandung

A lithium ion battery has been currently developed and produced because it has a high energy capacity, longer life time and the efficient use of lithium ion battery that is suitable for storing electrical energy for various electronic devices. However, this battery has some drawbacks such as use liquid electrolytes that are prone to leakage and flammability during the battery charging process in high temperature. One way to solve this problem is the use of a polymer electrolyte as a substitute for liquid electrolyte that serves as both the electrolyte and separator between anode and cathode component on batteries. In this study, a polymer matrix of chitosan was used because it has good mechanical strength, easy to modified, and also biodegradable. However, it has drawback such as low ion conductivity. To improve ion conductivity in chitosan, in this study the chitosan is modified with the addition of ionic liquids which have high ion conductivity and thermal properties, low vapor pressure, acting as a plasticizer, and also provide a charge carrier that is potential to improve chitosan property as electrolyte polymer. Ionic liquid used in this study is 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) containing Li+ ions. This ionic liquid was obtained from the anion metathesis reaction between EMImBr and LiBF4 salt, while EMImBr was synthesized from the reaction between 1-methylimidazol and bromoethane utilizing Microwave Assisted Organic Synthesis (MAOS) method. Ionic liquids obtained were characterized by microstructure analysis with using NMR and FTIR spectroscopy. The preparation of polymer electrolyte membranes was carried out by using the casting method of chitosan solution containing various compositions of EMImBF4/Li+, and then polymer electrolyte membrane was characterized by analysis functional groups (FTIR), ionic conductivity (EIS), crystallinity (XRD), surface morphology (SEM), thermal property (TGA), and mechanical strength (Tensile tester). The analysis results of ion conductivity by the EIS method were obtained the optimum ionic conductivity value about 1.30 x 10-2 S cm-1 on the polymer electrolyte membranes with the composition of 7.5% EMImBF4/Li+. The increase of ion conductivity is caused by the increase in amounts and mobility of ions within membrane due to the addition of ionic liquids, and this result was supported by analysis data of mechanic, crystalinity, surface morphology, and thermal analysis.