TRANSPORT AND STRUCTURAL CHARACTERIZATION OF NOVEL Li AND Mg-IONS CONDUCTING POLYMER ELECTROLYTES

• Main Author: LUH PUTU ANANDA SARASWATI (NIM:20517004), NI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29896
• Institution: Institut Teknologi Bandung

The massive use of electrical devices combined with the increasing concern for eco-friendly alternatives to the internal combustion engines is currently boosting the development of efficient mobile electrical devices. From cars to microelectronics, the increase in performance has raised the attention for high power battery technology based on liquid electrolyte lithium-ion batteries. The power output of a battery is strongly dependent on the type of the metal-ion system and the performance of the ion conducting electrolyte placed between the two electrodes. The low natural abundance and the safety drawbacks of lithium (handling, flammability, toxicity, and processability) stimulated the research for alternative metals and the development of solid state electrolytes, especially solid polymer based electrolytes. <br /> <br /> <br /> <br /> <br /> Among all the alternatives for Li-ion polymer electrolytes, poly(ethylene oxide)-lithium bis(trifluoromethanesulphonyl)imide (PEO-LiTFSI) showed the best performance so far and has been thoroughly studied. The main drawbacks of this systems are the crystallinity of the matrix, its mechanical properties, and a dramatic conductivity drop below 60 oC. To overcome these limitations, we investigated two groups of novel polymeric materials: poly(allyl glycidyl ether) (PAGE)-like polymers and PEO-poly(vinylidenefluoride) (PEO-PVDF)-based block copolymers. The first group (PAGE, PAGE thioether, and PAGE sulfone) preserves the PEO backbone but with three different pendant chain in the repeating unit, which inhibits crystallization and gives different dielectric properties. The (PEO-PVDF)-based block copolymers were designed to combine the advantage of block-copolymer nanophase separation, the good PEO ion conductivity, and high PVDF chemical and mechanical stability. <br /> <br /> <br /> <br /> <br /> The PAGE-like polymers synthesized for the first time in our labs, have been fully characterized in their neutral, Lithium (LiTFSI, LiCl) and Magnesium (Mg(TFSI)2, MgCl2) salt forms. Thermal, structural, and transport properties have been studied using different techniques (DSC, TGA, FTIR, and EIS). The same characterization has been pursued on the block copolymers whose thermal behavior has been investigated also by in-situ SAXS and WAXS. Among the PAGE-like polymers, sulfur-containing polymers (PAGE thioether and PAGE sulfone) gave the highest conductivities with chlorine salts (1.2 x 10-5 S/cm at 90 oC using LiCl salt), while the PAGE gave the highest conductivities with TFSI salts (6.4 x 10-4 S/cm at 90 oC). For what concern the block copolymers, PEO-b-(PVDF-TrFE) show the highest conductivity (8.5 x 10-4 <br /> <br /> <br /> <br /> <br /> S/cm) at 130 (formula)C, while PEO-b-(PVDF-HFP) show the highest conductivity (4.3 x 10-6 S/cm) at 20 (formula)C. We observed that the role of crystallinity is crucial and strongly affect the conductivity performance of the block copolymers