THE SYNTHESIS OF CELLULOSE PHTHALATE FROM CORNCOB'S WASTE AS FILLER IN CELLULOSE ACETATE/LITHIUM ACETATE-BASED POLYMER ELECTROLYTE MEMBRANES FOR LITHIUM ION BATTERIES APPLICATION

• Main Author: YURIANTY PRATIWI (NIM:20516022), RAVENSKY
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30262
• Institution: Institut Teknologi Bandung

Lithium ion batteries have a few advantages such us high energy density, long life <br /> <br /> cycles, and good flexibility. Using liquid electrolyte and separator in lithium ion battery <br /> <br /> carries a risk of leakage, explosion at high temperatures, corrosive and limited battery <br /> <br /> size. Solution to overcome the weakness is using a polymer electrolyte which is solid <br /> <br /> electrolyte material without a liquid component that can act as an electrolyte and a <br /> <br /> separator. Cellulose is one of the most abundant polymer in nature, renewable and <br /> <br /> environmental-friendly. One source of cellulose in nature is corncob’s waste containing <br /> <br /> 62.80% cellulose. Cellulose is crystalline, insoluble and limited in its application. The <br /> <br /> modification of cellulose into its derivatives is needed to increase its solubility, so it can <br /> <br /> be applied in various fields including polymer electrolyte membranes. Cellulose acetate <br /> <br /> is a fabricated polymer, degraded in nature, and has good mechanical properties, but its <br /> <br /> ionic conductivity is low. The addition of cellulose phthalate with longer side chains is <br /> <br /> expected to open and enlarge membrane pores, thereby increasing their ionic <br /> <br /> conductivity. The aim of this research is to synthesize polymer electrolyte membrane <br /> <br /> from cellulose acetate/lithium acetate as base material by adding cellulose phthalate, <br /> <br /> and perform various characterization such as functional group, ionic conductivity, <br /> <br /> mechanical strength, crystallinity, morphology and thermal characterization for lithium <br /> <br /> ion battery application. Cellulose was isolated from corncobs by reflux method, and <br /> <br /> modified into cellulose phthalate with anhydride phthalate in 1-butyl-3- <br /> <br /> methylimidazolium chloride ([BMIM]Cl) utilizing Microwave Assisted Organic <br /> <br /> Synthesis (MAOS) Method. Cellulose and cellulose phthalates were characterized by <br /> <br /> Fourier Transfer Infrared (FTIR) and X-Ray Diffraction Spectroscopy (XRD). FTIR <br /> <br /> spectrum shows that there is no peak of lignin and hemicellulose characteristics which <br /> <br /> means that cellulose has been isolated. Isolated cellulose was 37.80% of the weight of <br /> <br /> the corncob, and XRD result indicates a semi-crystalline cellulose with a crystallinity <br /> <br /> index of 56.76% and as cellulose polymorph type I. The result of functional group <br /> <br /> analysis with FTIR shows that cellulose phthalate was successfully synthesized with <br /> <br /> optimum condition at 120 oC for 25 minutes with yield of 16.05%. Based on mechanical <br /> <br /> properties and ionic conductivity of the membranes, the optimal cellulose <br /> <br /> acetate/lithium acetate membrane composition was 95/5 (%w/w) with ionic <br /> <br /> conductivity of 7.16 x 10-4 S cm-1, stress of 53.43 MPa and strain of 5.11%. For addition <br /> <br /> of cellulose phthalate 1, 3, and 5 (%w/w) on the optimum cellulose acetate/lithium <br /> <br /> acetate membrane, optimum mechanical strength and ionic conductivity in the cellulose <br /> <br /> acetate/lithium acetate/cellulose phthalate were obtained at composition of 92/5/3 <br /> <br /> (%w/w). The addition of cellulose phthalate can increase ionic conductivity up to 1.2 x <br /> <br /> 10-3 S cm-1, but decrease the tensile strength and strain to 48.62 MPa and 3.25%. Based <br /> <br /> on these data, it can be concluded that addition of lithium acetate salt and cellulose <br /> <br /> phthalate can increase ionic conductivity and sufficiently maintain the mechanical <br /> <br /> strength of the membrane. These results are supported by functional group, surface <br /> <br /> morphology, crystallinity and thermal properties analysis of the membrane. Based on <br /> <br /> the results, it has been concluded that the cellulose acetate/lithium acetate/cellulose <br /> <br /> phthalate polymer membrane is potential to be applied as a polymer electrolyte <br /> <br /> membrane for lithium ion batteries. <br />