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CHEM0064 Coursework 2023-24

Solid State Electrolytes (SSE) are gaining interest in the field of energy storage (batteries) as their higher structural and electrochemical stability, compared to organic and inorganic liquid electrolytes, allows higher power charging and discharging processes. Another advantage of SSEs, when employed with metal anodes, is that the solid electrolyte structure may prevent the formation and propagation of dendritic structures.

The so-called NASICON (Na Super Ionic CONductor) compounds are among the most researched SSEs for Na-ion batteries. They are based on the reference NaZr2P3O12 compound, where mobile excess Na+ ions are incorporated by doping P, Zr and possibly O sites with low-valent ions (e.g., Si4+ for P5+). Computer modelling is a valuable contributor to research as it can enable a screening of which dopant can be more easily incorporated in the structure, and can provide an insight into the effect of doping on the position and mobility of Na+ . Computational studies can also be employed to characterise the SSE surface structure, the deposition and dissolution of metallic Na (the battery anode) at the interface with the solid electrolyte.

A recent review on NASICON materials as SSEs for Na-ion batteries is given in reference [1], where table 2 lists a few known dopants and their effect on Na mobility. A list of dopants employed in a computational screening can also be found in table 1 of reference [2].

[1] Z. Yang et al, ChemElectroChem 8 (2021) 1035-47; doi.org/10.1002/celc.202001527

[2] B. Ouyang et al, Nature Commun 12 (2021) 5752; doi.org/10.1038/s41467-021-26006-3

Write a 1-page proposal discussing a computational study aimed at investigating a new dopant, composition, or surface termination of NaZr2P3O12, and/or its operation as SSE. In the proposal you need to specify:

1) which dopant/composition/surface you aim to study and why;

2) if relevant, how you will address the structure of the material, the location and/or mobility of Na in the bulk or surface;

3) which computational technique you propose to employ and why it is the most appropriate to address the problem set out in points 1 and 2, and

4) estimate how many distinct calculations you need to perform to investigate this problem, and the likely computational cost of the project