Atoms in Lithiated Carbon Fibres
Doctoral thesis, 2023

Carbon fibres are key constituents of structural batteries, in which electrochemical energy storage and mechanical load bearing are merged in one multifunctional device. Here carbon fibres simultaneously act as structural reinforcement by carrying load and as battery electrode by hosting lithium (Li)-ions in its microstructure. However, conventional carbon fibres are not designed to be multifunctional. To enable carbon fibres with optimised multifunctional capabilities, a fundamental understanding of their microstructure, chemical information and interaction with Li is required.

In this thesis, mass spectrometry and electron spectroscopy techniques are developed and used to elucidate the atomic distribution, configuration, and interaction in commercial carbon fibres used in structural batteries. Here the methodology of analysing Li in carbon fibres with atom probe tomography (APT) and Auger electron spectroscopy (AES) is demonstrated. Synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES) reveals that certain chemical states of N heteroatoms, pyridinic and pyrrolic, are connected to enhanced electrochemical performance of carbon fibres. AES shows that: Li distributes throughout the entire carbon fibre; the amount of trapped Li is higher and concentrated towards the centre of the fibre at increased discharge rates; Li is initially inserted in amorphous domains and with increased states of lithiation in crystalline domains; and Li plating can occur on individual fibres without spreading to adjacent fibres. APT on lithiated carbon fibres shows that: the distribution of Li is independent of the distribution of N heteroatoms; trapped Li is distributed uniformly in all domains; and Li agglomerates at elevated states of lithiation.

The work presented in this thesis paves the way for analysis of carbon-based battery materials with APT and AES. Furthermore, the work unveils much of the interplay between carbon fibre and Li and deepens the understanding of the design parameters for tailoring multifunctional carbon fibres used in improved structural batteries.

lithium insertion

atom probe tomography

synchrotron hard X-ray photoelectron spectroscopy

energy storage

carbon fibres

Auger electron spectroscopy

microstructure

heteroatoms

multifunctional composites

Virtual Development Lab (VDL), Hörsalsvägen 7A
Opponent: Dr Arun Devaraj, Pacific Northwest National Laboratory, WA, USA

Author

Marcus Johansen

Chalmers, Industrial and Materials Science, Materials and manufacture

Best Practices for Analysis of Carbon Fibers by Atom Probe Tomography

Microscopy and Microanalysis,;Vol. 28(2022)p. 1092 -1101

Journal article

Suppressing lithium migration in carbon fiber negative electrode during atom probe tomography analysis

Unravelling lithium in electrochemically active carbon fibres with atom probe tomography

We want our electric vehicles to drive longer before needing to recharge their batteries. However, most batteries add a lot to the weight of the vehicle and thereby limit the driving range. How do we make lighter energy storage systems? One solution, which can be said to remove all weight of the battery, is the structural battery. Instead of having a separate battery, the energy storage is integrated in the structural components, such as the roof of a car or the wings of an aircraft. The structural battery is made of many parts, and one of the most important parts is the carbon fibre, because the carbon fibre carries the load and stores the energy. By improving the carbon fibre, the structural battery is improved. However, to improve the carbon fibre we need more knowledge of how the carbon fibre looks and behaves on the micro- and nano-scale. Since, energy is stored by inserting lithium into the carbon fibre, it is especially important to understand how the carbon fibre interacts with lithium. For this thesis, we used several material characterisation techniques to answer questions of how atoms are bonded and distributed in the carbon fibre. With this newfound knowledge we now better understand the carbon fibre and what parameters can be tuned to improve their abilities. In the end, this research can lead to better structural batteries and increased driving range of electric vehicles.

Towards multifunctional batteries – insights into carbon fibres in dynamic electrochemical and mechanical processes

Swedish Energy Agency (2018-004406), 2019-01-01 -- 2023-12-31.

Driving Forces

Sustainable development

Innovation and entrepreneurship

Subject Categories

Materials Engineering

Atom and Molecular Physics and Optics

Materials Chemistry

Other Materials Engineering

Composite Science and Engineering

Areas of Advance

Transport

Energy

Materials Science

Infrastructure

Chalmers Materials Analysis Laboratory

ISBN

978-91-7905-916-3

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5382

Publisher

Chalmers

Virtual Development Lab (VDL), Hörsalsvägen 7A

Opponent: Dr Arun Devaraj, Pacific Northwest National Laboratory, WA, USA

More information

Latest update

8/31/2023