COMPOSITE OF CARBOXYMETHYL CHITOSAN AND LITHIUM ACETATE SALT WITH [EMIM]BR IONIC LIQUID ADDITION AS ELECTROLYTE POLYMER MEMBRANE

• Main Author: Pualam, William
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/79326
• Institution: Institut Teknologi Bandung

Currently, lithium-ion batteries have become a necessity for human life. The use of liquid electrolyte as an ion-conducting medium has the risk of leakage and explosion. Solid phase electrolytes such as polymer electrolyte membranes can be an alternative solution by modifying or adding additives that are needed, especially to increase the ion conductivity of the membrane. Natural biopolymers such as chitosan are quite promising for use as host polymer electrolytes because of their abundant availability, low price, and environmental friendliness. Chitosan has good thermal stability and mechanical properties, but it has low ionic conductivity. This research aims to increase the ion conductivity of chitosan polymer membranes through carboxymethylation to become carboxymethyl chitosan, then to optimize the ion conductivity and mechanical properties of the membranes by adding lithium acetate salt and 1-ethyl-3-methylimidazolium bromide ionic liquid. Ionic liquids are salts with a liquid phase at room temperature and have good thermal stability. Commercial chitosan that has a degree of deacetylation of 71.16% through carboxymethylation produced carboxymethyl chitosan with a percent yield of 90.42% and a degree of substitution of 1.188. Synthesis of [EMIm]Br ionic liquid by the MAOS method between imidazolium and ethylene bromide resulting in a yield of 61.10% and was confirmed by analysis of TLC, FTIR, 1H-NMR, and 13C- NMR analysis. Polymer electrolyte membranes were prepared by polymer solution casting method. The addition of ionic liquid into the membrane causes an increase in ion conductivity and conversely a decrease in mechanical properties. Optimum electrolyte polymer membrane properties were obtained in a composition of 25% (w/w) ionic liquid [EMIm]Br, and the addition of 34.3% mass of lithium acetate salt to produce a membrane with an ion conductivity value of 1.871 x 10-5 S/cm, tensile strength of 1.04 MPa, degree of crystallinity of 17.96%, and thermal stability up to a temperature of 240 oC. Based on the results above, this membrane has the potential to be used as a polymer electrolyte for lithium-ion battery cells.