Hybrid polymer-liquid electrolytes for lithium ion battery applications
Time: Fri 2024-10-25 10.00
Location: E3, Osquars backe 18, Stockholm
Video link: https://kth-se.zoom.us/j/66715840761
Language: English
Subject area: Fibre and Polymer Science
Doctoral student: Martina Cattaruzza , Ytbehandlingsteknik
Opponent: Professor Heikki Tenhu, University of Helsinki, Finland
Supervisor: Professor Mats Johansson, Wallenberg Wood Science Center, Ytbehandlingsteknik; Professor Göran Lindbergh, Tillämpad elektrokemi
QC 20240930
Abstract
The global shift towards renewable energy sources and the electrification of transportation necessitates advanced energy storage solutions, with lithium-ion batteries (LIBs) at the forefront. However, conventional batteries with liquid electrolytes in LIBs pose several limitations such as flammability, poor chemical stability, leakage risks, overall safety concerns, and limited processability. This thesis investigates hybrid polymer-liquid electrolytes (HEs) as an alternative to address these issues in LIBs as well as a way to obtain additional functionalities e.g. improved structural integrity.
The research is organized into four main studies. Paper I focuses on the three-dimensional (3D) reconstruction and analysis of HE structures. Using focused ion beam-scanning electron microscopy (FIB-SEM), the study reveals the complex, interconnected pore networks within HEs that are critical for ionic conductivity and mechanical stability.
Paper II explores the impact of porosity on the ionic and molecular mobility within HEs. By varying the liquid electrolyte content, the study demonstrates how increased porosity enhances ion mobility, directly correlating with improved electrochemical performance. Nuclear magnetic resonance (NMR) diffusion experiments further elucidate the transport mechanisms within the polymer matrix, showing a significant increase in ion diffusion rates with higher electrolyte content.
Paper III examines the role of nanosized carbon black (CB) particles in the polymerization-induced phase separation (PIPS) process used to synthesize HEs. The addition of CB improves the conductivity of HEs without compromising their morphological integrity. The study finds that even small amounts of CB can substantially enhance the overall conductivity, making CB-rich HEs potential candidates for multifunctional roles within battery electrodes, such as conductive binders.
Paper IV evaluates the practical application of HEs by integrating them into commercial LIB electrodes. The HE-infused electrodes maintain their structural and electrochemical properties even after multiple charge-discharge cycles, proving their potential for use in commercial applications.
This thesis contributes to the development of multifunctional electrolytes that not only address the safety issues associated with liquid electrolytes but also advance multifunctionality in LIBs. The methodologies and findings presented provide a foundation for future research in high-performance, safer, and more sustainable battery technologies.