Plasma-induced trilayer separator for lithium-ion batteries

• Main Author: Chong, Zhen Kang
• Other Authors: Alex Yan Qingyu
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/148419
• Institution: Nanyang Technological University

The separator is a crucial component in the lithium-ion batteries (LIBs) system as it will affect the battery performance. Yet, commercial battery separators such as polypropylene (PP) and polyethylene (PE) have low surface energy hydrophobic surfaces which results in low wettability and inability to absorb or retain the electrolyte. This will inhibit the overall electrochemical battery performance. Therefore, there is a need to alter the surface properties to fulfil the requirements of the current and future high-performance batteries. In this project, oxygen gas plasma treatment was performed on a trilayer (PP/PE/PP) membrane (Celgard 2325) to alter its surface properties from hydrophobic to hydrophilic by grafting with functional groups through radical reaction. The results had shown improvement for the electrolyte retention and wettability of the separator, except for its mechanical strength which was anticipated due to the etching drawback effects of using oxygen plasma. The cells with plasma-treated separator did not show improved charge-discharge capability and cycling performance due to experimental errors which could be rectified by conducting more tests to verify the results and improve the formulations for the electrodes. All in all, the results demonstrated that the plasma-treated separator is showing huge potential and may be used in LIBs in the future.