Functional polymers of intrinsic microporosity for battery energy storage
Author(s)
Wang, Anqi
Type
Thesis
Abstract
The research reported in this thesis is based on the molecular design and engineering of functional polymers of intrinsic microporosity (PIMs) and their applications as membrane separators in aqueous redox flow batteries (RFB) and as cathode materials in lithium-ion batteries. PIMs are composed of aromatic rings fused together by rigid, contorted structural units that lack conformational and rotational freedom, so that they pack space inefficiently, generating a large amount of sub-nanometre pores. The structural diversity of PIMs can be controlled by monomer choice, polymerization reaction and post-synthetic modification. Enabled by the synthetic modularity of PIMs, a range of chemical functionalities, namely, amidoxime, carboxylate, sulfonate and carbonyl groups, are introduced to the sub-nanometre pores in PIMs to enhance selective binding and explicit interactions with specific ions in aqueous or non-aqueous battery electrolytes. Analyte specific interactions and an open network of micropores with properly designed topologies and length scales in these functional PIMs allow fast, selective transport of ionic and molecular species, overcoming the conventional upper bounds of guest permeability and selectivity in polymer materials. A combination of physical, electrochemical and computational characterization techniques is employed to study the transport of water, ions and molecules within the nano-confined spaces in PIMs, providing molecular-level understandings for linking polymer pore architecture and chemistry to conductivity, transport selectivity, stability and redox activity. Functional PIMs demonstrate a new generation of ion-selective membranes that allow high-efficiency, high-power and long-cycling operations of all-organic aqueous redox flow batteries. PIMs with abundant accessible carbonyl groups enable solution-processing of electrodes with well-defined morphology and stable cycling performance in lithium-ion batteries.
Version
Open Access
Date Issued
2021-07-12
Date Awarded
01/09/2021
Advisor
Song, Qilei
Publisher Department
Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)