Conducting Polymer-based battery electrode matrices for Lithium-Ion batteries
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Date
2021-05-31
Authors
Nguyen, Van At
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Abstract
This thesis describes efforts to develop a new class of battery electrode matrices based on conducting polymers. In the introduction section, a summary of Li-ion battery architecture is briefly provided. Following that, some technical challenges for commercializing high-energy-density Li-ion batteries are highlighted to emphasize the necessity of designing better battery electrode architectures, where electrode matrices play a key role. Electrode matrices are typically composed of adhesive binders and conductive additives. Despite being used at a small quantity in battery electrodes (less than 20 wt%), electrode matrices act as both mechanical and electrical connection frameworks for functional Li-ion batteries. The inherent issues associated with the conventional electrode matrix, polyvinylidene fluoride/carbon black (PVDF/C), are then briefly described to signify the necessity of developing alternative electrode matrices. Subsequently, research objectives and methodologies are stated to draw a roadmap towards the development of new conducting polymer-based electrode matrices. The second chapter is a comprehensive literature review, reviewing how conducting polymers are integrated into different types of rechargeable batteries in the forms of binders and electrode matrices. The review chapter also reveals several research gaps in designing and understanding electrode binders/matrices derived from conducting polymers. The third chapter demonstrates an initial effort in developing inexpensive, self-conductive, water-processable conducting polymer-based electrode matrices from pyrrole and carboxymethyl cellulose. By performing in situ chemical polymerization of pyrrole in an aqueous solution of sodium carboxymethyl cellulose, composites of polypyrrole and carboxymethyl cellulose (PPy:CMC) are synthesized and then characterized. The study has proven that PPy:CMC composites are functional electrode matrices in terms of electrical conductivity and adhesion/cohesion efficiency. Without adding additional binders and conductive additives, LiCoO2/PPy:CMC cathodes perform as good as LiCoO2/PVDF/C reference cathodes. Chapter 4 demonstrates the application of PPy:CMC composites as electrode matrices for LiNi1/3¬Mn1/3Co1/3O2, which is an industry-relevant cathode material. Chapter 5 is dedicated to investigating the degradation of LiCoO2/PPy:CMC cathodes by means of electrochemical and post-mortem analyses. Several hypotheses on the degradation mechanism of LiCoO2/PPy:CMC cathodes are drawn and investigated. The last Chapter summarizes research outcomes and suggests potential research directions to expand the understanding and application of conducting polymer-based electrode matrices in Li-ion batteries and beyond.
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Keywords
Conducting polymers, Batteries, Electrode matrices
Citation
Nguyen, Van At, and Christian Kuss. 2020. “Review—Conducting Polymer-Based Binders for Lithium-Ion Batteries and Beyond.” Journal of The Electrochemical Society 167 (6): 065501. https://doi.org/10.1149/1945-7111/ab856b.
Nguyen, Van At, Jian Wang, and Christian Kuss. 2020. “Conducting Polymer Composites as Water-Dispersible Electrode Matrices for Li-Ion Batteries: Synthesis and Characterization.” Journal of Power Sources Advances 6 (September): 100033. https://doi.org/10.1016/j.powera.2020.100033.
Nguyen, Van At, Jian Wang, and Christian Kuss. 2020. “Conducting Polymer Composites as Water-Dispersible Electrode Matrices for Li-Ion Batteries: Synthesis and Characterization.” Journal of Power Sources Advances 6 (September): 100033. https://doi.org/10.1016/j.powera.2020.100033.