Batteries have found wide use in many household and industrial applications and since the 1990s, they have continued to rapidly shape the economy and social landscape of humans. Lithium ion batteries, a type of rechargeable batteries, have experienced a leap-frog development at technology and market share due to their prominent performance and environmental advantages and therefore, different forecasts have been made on the future trend for the lithium ion batteries in-terms of their use. The steady growth of energy demand for consumer electronics (CE) and electric vehicles (EV) have resulted in the increase of battery consumption and the electric vehicle (EV) market is the most promising market as it will consume a large amount of the lithium ion batteries and research in this area has reached advanced stages. This will consequently be resulting in an increase of metal-containing hazardous waste. Thus, to help prevent environmental and raw materials consumption, the recycling and recovery of the major valuable components of the spent lithium ion batteries appears to be beneficial. In this thesis, it was attempted to recover lithium from a synthetic slag produced using pyrometallurgy processing and later treated using hydrometallurgy. The entire work was done in the laboratory to mimic a base metal smelting slag. The samples used were smelted in a Tamman furnace under inert atmosphere until 1250oC was reached and then maintained at this temperature for two hours. The furnace was then switched off to cool for four hours and the temperature gradient during cooling was from 1250oC to 50oC. Lime was added as one of the sample materials to change the properties of the slag and eventually ease the possibility of selectively leaching lithium from the slag. It was observed after smelting that the slag samples had a colour ranging from dark grey to whitish grey among the samples.The X - ray diffractions done on the slag samples revealed that the main phases identified included fayalite (Fe2SiO4), magnetite (Fe3O4), ferrobustamine (CaFeO6Si2), Kilchoanite (Ca3Si2O7), iron oxide (Fe0.974O) and quartz (SiO2). The addition of lime created new compound in the slag with the calcium replacing the iron. The new phases formed included hedenbergite (Ca0.5Fe1.5Si2O6), ferrobustamine (CaFeO6Si2), Kilchoanite (Ca3Si2O7) while the addition of lithium carbonate created lithium iron (II) silicate (FeLi2O4Si) and dilithium iron silicate (FeLi2O4Si) phases.The Scanning Electron Microscopy (SEM) micrographs of the slag consisted mainly of Fe, Si and O while the Ca was minor. Elemental compositions obtained after analysis was used to identify the different phases in all the slag samples. The main phases identified were the same as those identified by the XRD analysis above except no phase with lithium was identified. No lithium was detected by SEM due to the design of the equipment as it uses beryllium planchets which prevent the detection of lithium.Leaching experiments were done on three slag samples (4, 5 and 6) that had lithium carbonate additions. Leaching was done for four hours using water, 1 molar HCl and 1 molar H2SO4 as leaching reagents at room temperature. Mixing was done using a magnetic stirrer. The recoveries obtained after leaching with water gave a lithium recovery of 0.4%. Leaching with HCl gave a recovery of 8.3% while a recovery of 9.4% was obtained after leaching with H2SO4.It can be concluded that the percentage of lithium recovered in this study was very low and therefore it would not be economically feasible. It can also be said that the recovery of lithium from the slag system studied in this work is very difficult because of the low recoveries obtained. It is recommended that test works be done on spent lithium ion batteries so as to get a better understanding of the possibilities of lithium recovery as spent lithium ion batteries contain other compounds unlike the ones investigated in this study.

This thesis presents a study on the design method to optimise the performance for producing green power from multiple renewable energy generators. The design method is presented through PLC (Programmable Logic Controller) theory. All the digital and analogue inputs are connected to the input cards. According to different operations conditions for each generator, the PLC will image all the inputs and outputs, from these images; a software program has been built to create a control method for multiple renewable energy generators to optimise production of green power. A control voltage will supply the output contractor from each generator via an interface relay. Three renewable generators (wind, solar, battery bank) have been used in the model system and the fourth generator is the back up diesel generator. The priority is for the wind generator due to availability of wind 24 hours a day, then solar, battery bank, and LPG or Diesel generators. Interlocking between the operations of the four contractors has been built to prevent interface between them. Change over between contractors, according to the generator's change over has also been built, so that it will delay supplying the main bus bar to prevent sudden supply to the load. Further study for controlling multiple renewable energy generators for different conditions such as controlling the multi-renewable energy generators from remote, or supplying weather forecast data from bureau of meteorology to the PLC directly as recommended. / Master of Electrical Engineering (Hons)

Graduation date: 1996

First principles computation can be used to investigate an design materials in ways that can not be achieved with experimental means. We show how computations can be used to rapidly capture the essential physics that determines the useful properties in different applications. Some applications for predicting crystal structure, thermodynamic and kinetic properties, and phase stability are discussed. This first principles tool set will be demonstrated with applications from rechargeable batteries and hydrogen storage materials. / Singapore-MIT Alliance (SMA)

Multiwall carbon nanotubes (CNTs) were synthesized by catalytic chemical vapor deposition of acetylene and used as templates to prepare CNT-Sb and CNT-SnSb₀.₅ nanocomposites via the chemical reduction of SnCl₂ and SbCl₃ precursors. SEM and TEM imagings show that the Sb and SnSb₀.₅ particles were uniformly dispersed in the CNT web and on the outside surface of CNTs. These CNT-metal composites are active anode materials for lithium ion batteries, showing improved cyclability compared to unsupported Sb and SnSb particles; and higher reversible specific capacities than CNTs. The improvement in cyclability may be attributed to the nanoscale dimensions of the metal particles and CNT’s role as a buffer in containing the mechanical stress arising from the volume changes in electrochemical lithium insertion and extraction reactions. / Singapore-MIT Alliance (SMA)

<p>The current work focuses on the synthesis and characterization of nano-devices with potential application in alkaline electrolysis and secondary polymer lithium ion batteries.</p>

This study highlights the importance of the anion in the electrochemical uptake of lithium by metal phosphides. It is shown through a variety of <em>in-situ</em> and <em>ex-situ</em> analytical techniques that the redox active centers in three different systems (MnP<i>₄</i>, FeP<i>₂</i>, and CoP<i>₃</i>) are not necessarily cationic but can rest almost entirely upon the anionic network, thanks to the high degree of covalency of the metal-phosphorus bond and strong P-character of the uppermost filled electronic bands in the phosphides. The electrochemical mechanism responsible for reversible Li uptake depends on the transition metal, whether a lithiated ternary phase exists in the phase diagram with the same M:P stoichiometry as the binary phase, and on the structure of the starting phase. When both binary and lithiated ternary phases of the transition metal exist, as in the case of MnP<i>₄</i> and Li<i>₇</i>MnP<i>₄</i>, a semi-topotactic phase transformation between binary and ternary phases occurs upon lithium uptake and removal. When only the binary phase exists two different behaviours are observed. In the FeP<i>₂</i> system, lithium uptake leads to the formation of an amorphous material in which short-range order persists; removal of lithium reforms some the long-range order bonds. In the case of CoP<i>₃</i>, lithium uptake results in phase decomposition to metallic cobalt plus lithium triphosphide, which becomes the active material for the subsequent cycles.

New ideas and solutions are necessary to face challenges in the electricity industry. The application of electricity storage systems (ESS) can improve the quality and stability of the existing electricity network. ESS can be used for peak shaving, instead of installing new generation or transmission units, renewable energy time-shift and many other services. There are few ESS technologies existing today: mechanical, electrical and electrochemical storage systems. Flow batteries are electrochemical storage systems which use electrolyte that is stored in a tank separated from the battery cell. Electrochemistry is very important to understand how a flow battery functions and how it stores electric energy. The functioning of a flow battery is based on reduction and oxidation reactions in the cell. To estimate the voltage of a cell the Nernst equation is used. It tells how the half-cell potential changes depending on the change of concentration of a substance involved in an oxidation or reduction reaction. The first flow battery was invented in the 1880’s, but was forgotten for a long time. Further development was revived in the 1950’s and 1970’s. A flow battery consists of two parallel electrodes separated by an ion exchange membrane, forming two half-cells. The electro-active materials are stored externally in an electrolyte and are introduced into the device only during operation. The vanadium redox battery (VRB) is based on the four possible oxidation states of vanadium and has a standard potential of 1.23 V. Full ionic equations of the VRB include protons, sulfuric acid and the corresponding salts. The capital cost of a VRB is approximately 426 $/kW and 100 $/kWh. Other flow batteries are polysulfide-bromine, zinc bromine, vanadium-bromine, iron-chromium, zinc-cerium, uranium, neptunium and soluble lead-acid redox flow batteries. Flow batteries have long cycle life and quick response times, but are complicated in comparison with other batteries. / Nya idéer och lösningar är nödvändiga för att möta utmaningarna i elbranschen. Användningen av elektriskt lagringssystem (ESS) kan förbättra kvalitén och stabiliteten av det nuvarande elnätet. ESS kan användas till toppbelastningsutjämning, istället för att installera nya produktions eller kraft överförnings enheter, förnybar energi tidsförskjutning och många andra tjänster. I dagsläget finns det få olika ESS: Mekaniska, elektriska och elektrokemiska lagringssystem. Flödesbatterier tillhör kategorin elektrokemiska lagringssystem som använder sig utav elektrolyt som är lagrad i en tank separerad från battericellen. För att kunna förstå hur flödesbatteriernas funktioner och på vilket sätt som dem lagrar elektriskt energi är det viktigt att kunna elektrokemi. Flödesbatteriernas funktion är baserad på reduktions och oxidations reaktioner i cellen. Nernsts ekvation används för att kunna uppskatta voltantalet i en cell. Nernsts ekvation säger hur halvcell potentialen ändras beroende av ändringen av koncentrationen av ämnet involverat i oxidations eller reduktions reaktionen. Det första flödesbatteriet uppfanns 1880-talet, men blev bortglömt under en lång tid. Vidare utveckling förnyades under 1950 och 1970-talet. Ett flödesbatteri består utav två parallella elektroder som är separerade utav ett jonbytes membran vilket formar två halvceller. Dem elektroaktiva materialen är lagrade externt i elektrolyt och är införs bara i anordningen under användning. Vanadium redox batteriet (VRB) är baserat på dem fyra möjliga oxidations tillstånden av vanadium och har en standard potential på 1.23 V. Fullt joniska ekvationer av VRB inkluderar protoner, svavelsyra och deras motsvarande salter. Kapitalkostnaden av ett VRB är ungefär 426 $/kW och 100 $/kWh. Det finna andra flödesbatterier som är polysulfide-brom, zink-brom, vanadium-brom, järn-krom, uran, neptunium och löslig blysyre redox flödesbatterier. Flödesbatterier har en lång omloppstid samt en snabb svarstid men är komplicerade jämfört med andra batterier.

This study highlights the importance of the anion in the electrochemical uptake of lithium by metal phosphides. It is shown through a variety of <em>in-situ</em> and <em>ex-situ</em> analytical techniques that the redox active centers in three different systems (MnP<i>₄</i>, FeP<i>₂</i>, and CoP<i>₃</i>) are not necessarily cationic but can rest almost entirely upon the anionic network, thanks to the high degree of covalency of the metal-phosphorus bond and strong P-character of the uppermost filled electronic bands in the phosphides. The electrochemical mechanism responsible for reversible Li uptake depends on the transition metal, whether a lithiated ternary phase exists in the phase diagram with the same M:P stoichiometry as the binary phase, and on the structure of the starting phase. When both binary and lithiated ternary phases of the transition metal exist, as in the case of MnP<i>₄</i> and Li<i>₇</i>MnP<i>₄</i>, a semi-topotactic phase transformation between binary and ternary phases occurs upon lithium uptake and removal. When only the binary phase exists two different behaviours are observed. In the FeP<i>₂</i> system, lithium uptake leads to the formation of an amorphous material in which short-range order persists; removal of lithium reforms some the long-range order bonds. In the case of CoP<i>₃</i>, lithium uptake results in phase decomposition to metallic cobalt plus lithium triphosphide, which becomes the active material for the subsequent cycles.

In this thesis, photocrosslinked ferrocene-based methacrylate polymers for thin-film cathodes in lithium batteries have been synthesized. Patterned thin-film electrodes of the ferrocene-based methacrylate polymers are fabricated by photocrosslinking. The structure and composition of the photocrosslinkable polymers are characterized by infrared spectra, nuclear magnetic resonances, and gel permeation chromatography. The result of quartz crystal microbalance shows that the crosslinked polymers prevent the polymers from dissolving into organic electrolytes. The cyclic voltammogram shows the photocrosslinked ferrocene-based methacrylate polymers have a redox couple. The energy capacity of the polymer for lithium batteries is about 40-50 mAh g-1 at a discharge rate of 10 C. The results show that the photocrosslinked ferrocene-based methacrylate polymers also improve the batteries.