Year of Award

2016

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Chemistry.

Principal Supervisor

Wong, Wai-Yeung(Chemist)

Keywords

Analysis;Lithium ion batteries;Semiconductor storage devices

Language

English

Abstract

This thesis is dedicated to developing three different types of ferrocene-containing polymers for organic lithium-ion battery and resistive memory applications. Chapter 1 gives an overview of organic cathode-active materials, polymeric resistive memories and ferrocene-containing polymers. Furthermore, the previously reported applications of ferrocene-containing polymeric systems in electrochemical energy storage and electronical memory devices were also comprehensively summarized. In chapter 2, conjugated ferrocene-containing side-chain metallopolymers PFcFE1, PFcFE2, PFcFE3 and PFcFE4 were designed and synthesized via Sonogashira cross-coupling polycondensation. The charging-discharging processes of triphenyamine-based PFcFE1 and thiophene-modified PFcFE4 have been successfully studied as cathode materials. PFcFE1 composite electrode showed a capacity of 90 mAh g-1 and the cathode composed of PFcFE4 retained over 90% of the initial capacity after 100 charging-discharging cycles at 10 C. These results demonstrate the great potentials of these ferrocene-containing side-chain polymers as active cathode materials for organic lithium-ion battery applicaitons. Besides, all prepared ferrocene-containing metallopolymers PFcFE1, PFcFE2, PFcFE3 and PFcFE4 also exhibited nonvolatile resistive switching behaviors with the flash memory effect of PFcFE1, PFcFE2 and PFcFE3 as well as the WORM memory feature of PFcFE4, indicating the easily tuned memory properties by changing the chemical structures of the active polymeric backbones. It is also worth noting that the ITO/PFcFE1/Al memory device showed a high ON/OFF current ratio of 103 to 104, a low switch-on voltage of -1.0 V, a long retention time of 1000 s and a large read cycle number up to 105, which is superior to other reported ferrocene-containing memory examples. Chapter 3 focuses on the development of non-conjugated ferrocene-containing copolymers PVFVM1, PVFVM1-1, PVFVM2, PVFVM3, PVFVM4, PVFVM5 and PVFVM6 based on different heteroaromatic moieties which were prepared by AIBN initiated chain addition polymerization. The as-prepared copolymers PVFVM1 and PVFVM1-1 exhibited electrochemical characteristics of both ferrocene and triphenylamine pendants with reversible multiple redox waves at the half potentials of E1/2 = --0.06, 0.30, and 0.42 V (vs. Fc/Fc+). Notably, the composite electrode based on PVFVM1 afforded a discharge capacity of 102 mAh g--1 at 10 C, corresponding to 98% of its theoretical capacity. The cycle endurances of the active polymer electrodes composed of PVFVM1 or PVFVM1-1 were both evaluated for over 50 numbers and no significant capacity reduction over cycles were observed. On the other hand, initial I-V results of memory devices based on PVFVM1, PVFVM1-1, PVFVM2, PVFVM3, PVFVM4 and PVFVM6 also revealed their huge potentials in electronic information storage. The stability and reproducibility of the corresponding memory devices based on these materials will be futher evaluated in the near future. We used 1,1'-ferrocenediboronic acid bis(pinacol) ester to develop conjugated ferrocene-containing main-chain metallopolymers in chapter 4. All these rational designed metallopolymers FcMMP1, FcMMP2, FcMMP3 and FcMMP4 with one or two ferrocene moieties were produced via Suzuki cross-coupling polycondensation. Their structural information, molecular masses, photophysical features and thermal properties have been well studied. Electrochemical performances of the formed polymers were also examined to clarify their potential as cathode-active materials. Other charge-storage characteristics and switching behaviors of these prepared ferrocene-containing main-chain metallopolymers for organic battery and memory applications are under further investigation.

Comments

Principal supervisor: Professor Wong Wai Yeung.;Thesis submitted to the Department of Chemistry.Thesis (Ph.D.)--Hong Kong Baptist University, 2016.

Bibliography

Includes bibliographical references.

Copyright

The author retains all rights to this work. The author has signed an agreement granting HKBU a non-exclusive license to archive and distribute their thesis.



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