Polyanionic electrode materials for sodium-ion batteries
About this project
This PhD research project aims to develop polyanionic materials with improve sodium ion storage capacity, power density, operating voltage, cyclic stability, and rate capability. The research scope includes mainly synthesis and characterisation of sodium vanadium phosphate materials with a sodium super ion conductor (NASICON) structure such as Na3VTi(PO4)3 in the following 4 steps:
Synthesise and characterise pure phase Na3VTi(PO4)3 by using both solid-sate reaction and sol-gel methods. Instrumental analysis and electrochemical characterization of samples prepared will be conducted to get optimum results.
Improve electrical conductivity of Na3VTi(PO4)3 using carbon materials, including nitrogen and sulphur doped carbon, carbon nanotubes and graphene. Instrumental analysis methods and electrochemical characterisation tools will be used to characterise samples’ electrical conductivity and rate capability.
Improve the operating voltage of the above obtained highest conductivity sample by modification with fluorine and oxygen functional groups. Structural and electrochemical characterization will be conducted to optimise the material’s performance.
Electrode will be prepared using the above material, and assessed using both half cell and full cell setups.
Synthesis of cathode materials:
a) The solid-state reaction method will be used to prepare Na3VTi(PO4)3 particles of micrometer size.
b) The sol-gel method will be used yo synthesize Na3VTi(PO4)3 of nanometer size.
Electrode fabrication: The synthesised cathode material is mixed with additives (carbon materials) and binders to increase the conductivity, elasticity, and mechanical strength.
Half-cell and full-cell fabrications:
The electrode will be transferred to a nitrogen-filled glove box to be fabricated in a half-cell using the standard CR-2036 buttons cell, or a full cell using hard carbon as the anode.
Structural Characterisation methods:
a) Phase and purity will be characterized using the X-ray diffraction (XRD) technique.
b) The particle morphology and size will be characterised by the scanning electron microscope (SEM) and high-resolution transmission electron microscope (HR-TEM) methods.
c) Elemental analysis and chemical state analysis will be carried out using the X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and Fourier transformed infrared spectroscopy (FTIR) methods.
e) Confirmation of valence state, local atomic environment and bond strengths through Extended X-ray Absorption Fine Structures (EXAFS) / X-ray Absorption Near Edge Structure (XANES).
a) Galvanostatic charging-discharging of the fabricated cells at different current densities
b) Cyclic voltammetry analysis of freshly fabricated cells. The cells after some cycles of charging-discharging at different scan rates to determine the kinetics of the cell reaction.
c) Temperature-dependent electrochemical impedance spectroscopy (EIS) analysis of coin cells to know the impedance of individual components of the cell as the reaction progress.
d) Determination of phase change of the active material with respect to voltage during charging-discharging through in-situ XRD.
e) Determination of change in valency, local environment and bond strength during charging-discharging through in-operando Extended X-ray Absorption Fine Structures (EXAFS) / X-ray Absorption Near Edge Structure (XANES).
This project focuses on developing advanced cathode materials with high specific capacity and voltages to produce practical sodium-ion batteries for applications such as short-range electric vehicles and large-scale grid energy storage. The following outcomes are expected:
2-4 papers published in high impact journals.
1-2 patents filed.
A joint research proposal submitted to funding agencies such as the ARC.
Information for applicants
Essential knowledge in chemistry, good writing and communication skills in English, able to conduct experimental work after training.
Some research experience in materials synthesis and characterisation, electrochemistry, rechargeable batteries.
Expected qualifications (Course/Degrees etc.)
Master of Philosophy degree, or Bachelor’s degree with at least honours class IIA or equivalent; or coursework master’s degree with an overall grade point average of 5.65 on the 7-point scale in chemical engineering or chemistry or physics or materials science and engineering.
Additional information for applicants
note: i-students must have own scholarship to apply (CSIR, UCG-NET, etc)