Advanced Characterisation of Anode Materials Including Ball Milled, Exfoliated, and Porous Electrode Materials for Li-ion and Na-ion Batteries

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Advanced Characterisation of Anode Materials Including Ball Milled, Exfoliated, and Porous Electrode Materials for Li-ion and Na-ion Batteries

Shah, Ami Rani; (2025) Advanced Characterisation of Anode Materials Including Ball Milled, Exfoliated, and Porous Electrode Materials for Li-ion and Na-ion Batteries. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Energy storage devices such as rechargeable batteries play a crucial role in tackling climate change. However, significant improvements to existing technologies are necessary to meet consumer requirements of cheaper batteries with increased power and capacity. These properties critically depend on electrode material structures and compositions. Here, graphite, molybdenum disulfide (MoS2), and hard carbon (HC) materials were characterised and investigated for their potential use as anodes in Li-ion and Na-ion batteries. MoS2, a layered material similar to graphite, exhibits a much larger capacity for Li-ion batteries, yet struggles with high-rate capability and cycle life due to its insulating nature and structure degradation. Efforts in combining MoS2 and graphite have led to improvements in the electrochemical performance of MoS2/graphite composites, however, their syntheses are often complicated and expensive. In this work, MoS2 and graphite were simply ball milled to form a composite with exceptional rate capability. Various material characterisation including Raman spectroscopy, BET, XPS, SEM, and XRD suggested the formation of an intimately linked MoS2/graphite structure by potentially forming new bonds. In another study, MoS2/graphite composites were synthesised by intercalation via metal-ammonia solutions and subsequent exfoliation. Exfoliated materials exhibited higher capacities and extended cyclability resulting from smaller and expanded crystallites, identified by Raman spectroscopy and XRD. HC, a porous material comprising of carbon atoms arranged in turbostratic nanodomains, is the current primary candidate for Na-ion battery anodes. HC accommodates sodium through interlayer spaces, within nanopores/micropores, and upon edge/defect sites. There remains a debate over the origins of slope and plateau regions of the charge-discharge profile for HC. Ex situ and operando neutron total scattering were used to interrogate sodium insertion at different length scales simultaneously. It was found that the interlayer spacing of the turbostratic nanodomains continued to expand even at low insertion voltages. Additionally, the surface area and surface roughness changed with the degree of sodiation and desodiation, suggesting the extent of solid-electrolyte interphase formation and dissolution. This work provides insights into the sodiation mechanisms of HCs and highlights the necessity for operando studies of this nature. To conclude, a more comprehensive understanding of material structures is essential in choosing materials for optimising battery performance, and the advanced characterisation techniques described above prove to be valuable tools for their study.

Type:	Thesis (Doctoral)
Qualification:	Ph.D
Title:	Advanced Characterisation of Anode Materials Including Ball Milled, Exfoliated, and Porous Electrode Materials for Li-ion and Na-ion Batteries
Open access status:	An open access version is available from UCL Discovery
Language:	English
Additional information:	Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification:	UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI:	https://discovery.ucl.ac.uk/id/eprint/10203407