As part of our mission to develop the next-generation of energy storage scientists and engineers, the Faraday Institution is funding sixteen undergraduate internships in universities across the UK over the summer 2018. These 8-week internships provide undergraduates with access to leading scientists and unique facilities in order to participate in hands-on research activities.
Simple ionic-liquid mixtures as battery electrolytes
Charles Monroe, Oxford University
On the basis of their low volatility and resistance to burning, ionic liquids have been suggested as a promising replacement for the non-aqueous solvents used in present-day lithium-ion batteries. Since they are themselves composed of mobile charge carriers, one might intuitively suppose that ionic liquids should exhibit much different transport properties than standard electrolytic solutions. The diffusion and mobility (drift) of lithium ions in ionic liquids remain poorly understood, however, because standard transport theory does not assume the solvent to be composed of ions. Development of a thermodynamically consistent model of ionic-liquid solutions is an open problem in electrolytic transport theory.
This project will focus on using Onsager-Stefan-Maxwell transport theory to develop flux laws for the description of mass and charge transport in simple three-ion ionic-liquid mixtures, for example LiTFSI dissolved in the ionic liquid bmimTFSI. The aim will be to identify how molecular-scale ion/ion interactions manifest as macroscopic transport properties like the ionic conductivity of the solution, the salt diffusivity, and the lithium transference number. Some experimental data has already been gathered, which can be used to test a transport model.
Can we understand the dependence of cell voltage on electrode structure in Li-ion batteries?
Harry Hoster, Lancaster University
Li-ion cells are well established in their application in electronic devices, are becoming the predominant technology in electric vehicles and could play an important role in the storage of energy from renewable sources. As any frustrated mobile phone user knows, the cell lifespan is limited. Gaining understanding of how structural changes in Li-ion cells can affect their voltage profiles, that is, how the cell voltage depends on the proportion of lithium in the electrodes, is important to characterising the aging of the cells and diagnosing cell failure.
To better understand the relationship between electrode structure and cell voltage, the proposed project will use and adapt existing simulation tools to model already collected commercial cell data, at the level of individual electrodes (anode and cathode separately), and if time permits, in the case of full cells. This will be achieved by combining mean field simulation techniques developed at Lancaster with experimental Li-ion Kokam pouch cell data from Oxford. Mean field techniques make certain simplifying assumptions about the interactions between the Li ions in the electrodes. They allow for rapid calculation of (free) energy values as the Li contents change in positive and negative electrode. The resulting computational predictions of voltage profiles can then be quantitatively fitted to corresponding experimental data, thus closing a validation loop.
Data archiving and visualisation
Paul Shearing, University College London
Collection, handling, visualising and sharing data is one of the major challenges in modern scientific research: in the Faraday Institution, we seek to engage across disciplines and between interested parties from school-children to CEOs. Li-ion batteries exemplify this problem: we are all reliant on battery technologies, but for many they remain a ‘black box’, even for those engaged with battery research there is often no shared vernacular which enables researchers to communicate across conventional discipline borders. At UCL we specialise in the application of multi-scale Xray imaging to understand advanced batteries – in this project we will use this case study to develop a platform for data handling and visualisation and presentation to a range of audiences of varying scientific literacy.
From materials to control
Dhammika Widanalage, Warwick University
Battery engineering is becoming increasingly multidisciplinary. Future engineers will require having an understanding and appreciation of the battery material constituents, intelligent software development and hardware components that go in to designing complex battery-pack systems. In this exciting and challenging internship, you will work on performing experiments to identify electrochemical performance parameters (first 4 weeks) and use them to evaluate a complex battery model and its performance for next generation battery-pack control systems (last four weeks). You will work with three WMG academics and be supported by research fellows during your internship, and will therefore be part of a multidisciplinary research team. You will also have the opportunity to meet other leading UK academics and researches working on the Faraday Multiscale Modelling project dedicated to the advancement of battery modelling. The successful completion of this internship will offer several benefits, from learning topics in electrochemistry, systems modelling and control, developing your skills in electrochemical testing, mathematical coding and teamwork for successful research delivery.
Observation and interpretation of degradation of Li ion batteries in a CT machine
Norman Fleck, Cambridge University
A common degradation mechanism for Li ion batteries is cracking due to swelling. In order to develop accurate models to predict the life of the battery, it is necessary to understand the degree of battery swell and the accumulation of microcracks. This can now be done through use of a micro CT X-ray machine with 3D reconstruction of the internal microstructure of the battery. A high resolution machine has been recently purchased, and the air of the project is to use it to measure battery swell and deterioration during the charge and discharge cycle.
Model Metal-Cathode Constructs for High-Resolution Interfacial Analysis of Battery Systems
Mary Ryan, Ainara Aguadero, Ifan Stephens of Imperial College London
The ambition to move to cleaner low carbon-emission cities requires a more widespread adoption of battery electric vehicles (BEVs). However, the degradation of current lithium-ion batteries, limits battery lifetime making BEVs unattractive to consumers. Developing a mechanistic understanding of the degradation mechanisms, across multiple length scales is key to both mitigating degradation in current systems and to optimizing the development of future more robust batteries. Our interest in particular is of the nanoscale processes, and this requires the development of well-controlled model systems that are representative of real battery hierarchies. In battery systems, the interfaces are typically sites of initiation of degradation: in this project, we will focus on the cathode, and in particular its interaction with both the electrolyte and the metallic current collector. We will construct metal-cathode model systems of industry relevant materials (e.g. LiNixMnxCoxO2 (NMC)), using layered thin film deposition.
The constructed models will provide a platform for studying chemical and physical changes at the metal/cathode/electrolyte interfaces under high stress conditions using techniques such as X-ray absorption spectroscopy (XAS) and electron microscopy/spectroscopy. Elucidating these changes will provide more insight on the chemical reactions taking place at the cathode, which ultimately affect the overall battery degradation. The student undertaking this project will also be involved in the design and fabrication of a 3D-printed electrochemical cells to facilitate in situ studies of the model systems.
Novel pulse techniques for battery evaluation
Ulrich Stimming, Newcastle University
The aim of this project is to develop a novel battery management system (BMS) that can be used to monitor important criteria such as the state of charge (SoC) and state of health (SoH) of lithium-ion batteries. This will be achieved through the implementation electrochemical methods including electrochemical impedance spectroscopy, and various pulse measurements together with logging of real-time battery data such as voltage, current, and temperature. The BMS should be suitable for use in commercial applications, such as the regulation of a car battery, and will be tested on small commercial Li-ion batteries.
The successful candidate will use the electrochemical techniques described to study the responses of the battery at various temperatures, states of charge/health etc. In analysing these responses, the student will identify the modes of degradation and quantify their effect.
Controlling the size of nanostructured NMC cathode particles and scaling up synthesis
Serena Corr, University of Glasgow
High nickel-content in battery electrodes allows us to access higher capacities, for example in systems such as LiNixMnyCozO2 (NMC). Differences in particle microstructure can enormously affect the rate performance of these materials. Establishing reproducible routes to nanostructured high nickel-content cathode materials is therefore of great importance, particularly for assessing the effect particle size has on resulting electrochemical properties and degradation processes. A summer placement project is available in the Corr group at the University of Glasgow to establish new sol-gel microwave approaches to obtain uniform nanostructures of the high nickel content material LiNi0.8Mn0.1Co0.1O2 (NMC-811). Working as part of a research team based in the new Functional Materials laboratory at the School of Chemistry, you will be trained in a variety of synthetic approaches to electrode materials and characterisation methods such as X-ray powder diffraction, electron microscopy, elemental analysis, and impedance spectroscopy. You will also be trained to build and test battery cells to establish best performing materials from the samples you will prepare.
Non-destructive testing of batteries for recycling gateway testing
Simon Lambert, Newcastle University
Central to the ReLiB project is the pre-analysis of batteries in a non-destructive manner to test the efficacy of the battery. It is essential to determine whether the performance of a battery is limited by individual cells, by a general degradation of all cells or by a mechanical failure. As the architecture of an automotive battery can be extremely complex and analysis of the battery health needs to be rapid, methods need to be investigated to simultaneously probe battery performance. This project will use electrochemical impedance spectroscopy (EIS) for gateway testing. This will use critical element analysis to breakdown the various aspects of the battery into equivalent circuits and compare the models for new and used batteries. The project will introduce the student to the structure of batteries and the use of EIS.
Investigating the potential for F contamination in Li ion battery cathode materials
Paul Anderson, University of Birmingham
There are a variety of methods by which fluorine can become incorporated into the electrode materials of a lithium ion battery, most notably from breakdown of the electrolyte during charging and discharging. Build-up of fluorine containing compounds can be problematic from the perspective of battery performance but mostly it causes difficulties when the battery is recycled. This study will investigate the sources of such contamination, the extent to which it occurs in used batteries and the types of materials which are produced. It will introduce the student to battery chemistries, analysis of fluorine containing compounds and material analysis.
Electrocatalytic methods of electrode material digestion
Andy Abbott, University of Leicester
Electrocatalysis has been shown to be an efficient and selective method of solubilising and recovering metals. This project will investigate for the first time how selective this can be. Using shredded battery material, a protocol will be developed to selectively release metal oxide from the copper substrate and physically recover it from solution. This will be done for both aqueous and ionic liquids. The kinetics of the process will be determined and a model constructed for the space-time yield. The project will introduce the student to microscopic and surface analysis as well as electrochemistry.
The state of the art in chemical, physical & biological recovery of critical metals from lithium ion batteries--a literature review
Tim Overton, University of Birmingham
While there is a significant literature on different methods of processing some of the materials found in lithium ion batteries but there is also a significant literature on processing the individual elements which had not been integrated. This literature review will bring together standard pyrometallurgical techniques with wet chemical and biological methods. Where possible, data on process efficiency will be metricised so that techniques can be compared. This will be a useful resource for both researchers and PhD students embarking on research in this area.
Nano and micro mechanical properties of solid electrolytes
David Armstrong, University of Oxford
The ceramic lithium ion conductors Li1.4Al0.4Ge1.6(PO4)3 (LAGP) and Li7La3Zr2O12 (LLZO) have been shown to be promising electrolyte materials for solid state lithium ion batteries. While their electrochemical properties have been well studied there is comparatively little information on the mechanical properties of these materials. This data is a key requirement for the development of a better model of the mechanical behaviour of the materials during the charge-discharge cycle.
This project will use a range of nano and mico-mechanical indentation methods to study, the hardness, elastic modulus, yield stress and fracture toughness of both materials. These properties will be related to local microstructural features through the use of scanning electron microscopy (SEM), Electron back scattered diffraction (EBSD) and Raman Spectroscopy. Finally these micromechanical properties will be compared to bulk fracture properties obtained through four point bend flexure tests. The data produced in this way will not only be useful for seeding models but allow optimisation of processing routes for producing electrolytes with improved lifetimes.
Developing novel Ti-based lithium stuffed garnets as potential solid-state electrolytes
Edmund Cussen, University of Strathclyde; Hany El-Shinawi, University of Glasgow
The need for greener, safer batteries makes all-solid-state batteries a promising candidate to replace current lithium ion battery technology employing hazardous flammable organic liquids. Lithium stuffed garnets are the best known solid-state electrolytes in terms of lithium ion conductivity and stability in contact with lithium anodes. Manipulating composition and microstructure of these materials enormously affect their performance as potential solid-state electrolytes. A summer placement project is available in the Cussen group in collaboration with Dr Hany El-Shinawi at the University of Glasgow to develop novel Ti-containing lithium stuffed garnets (Li7-xLa3(Zr,Ta,Ti)2O12) and characterize their performance in all-solid-state batteries. Working as part of a research team, you will be trained in a variety of synthetic approaches, including solid-state and sol-gel methods, and characterisation methods such as X-ray powder diffraction, electron microscopy, X-ray photoelectron microscopy, and impedance spectroscopy. You will be trained to manufacture and characterize solid-state electrolytes and employ them in appropriate solid-state battery configurations.
Thin film Li7La3Zr2O12 solid electrolytes by sputtering
Susie Speller and Chris Grovenor, Oxford University
Rechargeable lithium-ion batteries have revolutionized the portable electronics industry because of their high energy density and efficiency. However, they suffer from safety and reliability issues, many of which are related to the use of flammable liquid electrolytes. There is a world-wide race to design and manufacture solid-state electrolyte materials that could resolve these problems. Candidate Li+ ion conducting garnets like Li7La3Zr2O12 have lower conductivities than liquid electrolytes, but show promise for use in prototype all solid-state battery designs if the thickness of the electrolyte can be reduced. However, a reliable growth process will have to be designed to give the necessary uniformity and electrochemical performance in thin films of these complex oxides. This summer project will explore the deposition of Li-garnet thin films by magnetron sputtering. The influence of the deposition parameters on the phase and microstructure and of the films will be studied using XRD and electron microscopy techniques to establish optimised growth conditions, and the electrochemical properties of the most promising films will be measured.
Identifying and comparing the network topologies underlying fast lithium ion conductors
Matthew Dyer, University of Liverpool
The crystal structures of porous materials such as zeolites and MOFs are often classifieds and analysed in terms of their topology. Structural elements are defined as the vertices and edges of a net, which can then be identified according to its connectivity. In this project we propose to analyse the structures of fast lithium ion conducting oxides and sulphides in the same way. We will use different definitions of vertices and edges to search for common underlying topologies. This will allow us to search for other materials with the same or closely related topologies which will also be excellent candidates for fast lithium ion conductivity.
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