Selective transport of the target ions including H+, Li+ and Na+, is pivotal to the development of efficient, economical energy storage devices. Most ion-conducting materials rely on carriers (vehicle) to transfer the target ion, where the ion conduction is strongly coupled to the carrier mobility. Grotthuss-type conduction (structural diffusion) has been observed in inorganic conductors such as CsHSO4 crystal, but it has been a persistent challenge to be implemented in polymer systems1. From a fundamental level, a hopping conduction through a polymer matrix requires i) decoupled charge carrier and host and ii) densely packed hopping sites (functional groups) which allows the proton to transfer. The latter is usually the major energy barrier for ion hopping. DFT calculations show that an efficient proton transfer requires the distance between two amphoteric groups to be less than two angstroms2.
This remains to be an issue for polymer-based electrolytes, but it can be readily achieved by atomically precise integration of organic units in Covalent Organic Frameworks (COFs) to create predesigned skeletons and nanopores. Recently, Xu et al.3, studied proton conduction across hexagonally aligned mesoporous COF channels, and showed that these highly ordered nanopores can promote proton structural diffusion, and achieve conductivities that 2~4 orders of magnitude higher than those of microporous and non-porous polymers3. This work clearly demonstrates the possibility of developing proton-conducting COFs with both high conductivity and ion selectivity.
1. Yang, H., Zhang, J., Li, J., Jiang, S.P., Forsyth, M., Zhu, H. J. Phys. Chem. Lett. 2017, 15, 3624.
2. Choi, U.H., Lee, M., Wang, S., Liu, W., Winey, K.I., Gibson, H., Colby R.H. Macromolecules, 2012, 45, 3974.
3. Xu, H. & Jiang, D. Nature Chem. 2014, 6, 564.
This project will investigate the effect of chemistry and nano-structures (pore size and length, tortuosity) of COFs on the ion selectivity and transport mechanisms of the target ions.
We will consider synthesizing three class of COF structures with various surface chemistry: i) hydrophobic; ii) hydrophilic and iii) positively charged surfaces, with the aim of manipulating ion selectivity through hydrogen bonding and ionic interactions. TPB-DMTP-COF3, known to exhibit good structural integrity, porosity and chemical stability, has been successfully synthesized recently by my collaborator. Multi-nuclear solid-state and pulse-field gradient NMR will be utilized to study the ion transport and selectivity of the COF-based electrolytes. Crystalline structures will be characterized by SAX and WAXRD techniques. Other complementary techniques including DSC, impedance spectroscopy and cyclic voltammetry will be used to characterize the thermal and electrochemical properties.
A lab-scale energy storage device prototype, e.g., PEM fuel cell will be assembled based on the selected COF-based composites. The cell performances including conductivity and current/voltage stability will be evaluated in-situ.
Applications close 5pm, Friday 16th August 2019
This scholarship is available over 3 years.
- Stipend of $27,596 per annum tax exempt (2019 rate)
- Relocation allowance of $500-1500 (for single to family) for students moving from interstate or overseas
- International students only: Tuition fee and overseas health coverage for the duration of 4 years
To be eligible you must:
- be either a domestic or international candidate
- meet Deakin's PhD entry requirements
- be enrolling full time and hold an honours degree (first class) or an equivalent standard master's degree with a substantial research component.
Please refer to the research degree entry pathways page for further information.
Additional desirable criteria include:
- Experience in organic synthesis, preferably in COF materials and proton conducting materials
- Excellent written and oral communication, reporting and presentation skills
- Excellent publication record
How to apply
Interested applicants should email the expression of interest form and CV to Dr Haijin Zhu
For more information about this scholarship, please contact Dr Haijin Zhu
Dr Haijin Zhu
Email Haijin Zhu
+61 3 522 73696