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This thesis describes an investigation of some of the factors which govern the operation of the commercially important Li-SOCl2 cell. Electrode processes at lithium anodes and C-SOCl2 cathodes have been studied using the technique of Faradaic impedance. A kinetic interpretation of the results has been advanced. Additionally some aspects of the formation and nature of LiCl films, which frequently cover the anode surface have been revealed from the decomposition of the numerical data. The impedance study further yielded kinetic data relating to the lithium dissolution process. Complementary preliminary studies of the impedance of glassy carbon-SOCl2 cathodes have shown that the cathode process is complicated.

Thesis advisor: Udayan Mohanty / Rechargeable batteries, especially lithium ion batteries, have greatly transformed mobile electronic devices nowadays. Due to the ever-depletion of fossil fuel and the need to reduce CO2 emissions, the development of batteries needs to extend the success in small electronic devices to other fields such as electric vehicles and large-scale renewable energy storage. Li-ion batteries, however, even when fully developed, may not meet the requirements for future electric vehicles and grid-scale energy storage due to the inherent limitations related with intercalation chemistry. As such, alternative battery systems should be developed in order to meet these important future applications. This dissertation presents our successes in improving Li-O2 battery performance for electric vehicle application and integrating a redox flow battery into a photoelectrochemical cell for direct solar energy storage application. Li-O2 batteries have attracted much attention in recent years for electric vehicle application since it offers much higher gravimetric energy density than Li-ion ones. However, the development of this technology has been greatly hindered by the poor cycling performance. The key reason is the instability of carbon cathode under operation conditions. Our strategy is to protect the carbon cathode from reactive intermediates by a thin uniform layer grown by atomic layer depostion. The protected electrode significantly minimized parasitic reactions and enhanced cycling performance. Furthermore, the well-defined pore structures in our carbon electrode also enabled the fundamental studies of cathode reactions. Redox flow batteries (RFB), on the other hand, are well-suited for large-scale stationary energy storage in general, and for intermittent, renewable energy storage in particular. The efficient capture, storage and dispatch of renewable solar energy are major challenges to expand solar energy utilization. Solar rechargeable redox flow batteries (SRFBs) offer a highly promising solution by directly converting and storing solar energy in a RFB with the integration of a photoelectrochemical cell. One major challenge in this field is the low cell open-circuit potential, mainly due to the insufficient photovoltages of the photoelectrode systems. By combining two highly efficient photoelectrodes, Ta3N5 and Si (coated with GaN), we show that a high-voltage SRFB could be unassistedly photocharged and discharged with a high solar-to-chemical efficiency. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

<p>Lithium-ion batteries are regarded as the batteries that could potentially change the world. From consumer electronics and electric vehicles to energy storage systems and aerospace applications, Li-ion based batteries have become the norm. Although these batteries show a lot of promise to rid the world of several challenges in the future, there are still a few shortcomings of this battery that need to be addressed. It is also important to note the recent accidents caused due to the explosion of these lithium-ion batteries, to name a few: Samsung Galaxy Note 7 explosion, e-cigarettes battery explosion, overheating of lithium batteries present in Apple MacBook Pro laptop. This calls for a more reliable and accurate Battery Management System (BMS). One of the major shortcomings in today’s available battery management systems is the accuracy of the measurement of charge present in lithium-ion batteries, termed as State-of-Charge (SoC) and State-of-Energy (SoE) of the battery. </p> <p>To address this problem, a highly sensitive and a high-resolution system is developed to estimate the State-of-Charge based on the changes in impedance of a sensor coil which is caused due to the effect of Eddy Current Power Loss in the battery. The redox reaction taking place inside a battery suggest that lithium ions are exchanged back-and-forth between anode and cathode during an event of charging and/or discharging of the battery. This gives rise to change in electrical resistivity of the battery electrode materials. A sensor coil which is excited with an AC magnetic field induces Eddy currents on the internal components of the battery. Based on the change in resistivity of the electrode materials, eddy current and hence the power loss due to Eddy currents change. This in turn changes the complex impedance of the sensor coil, which is mapped to estimate the SoC of the battery. The results confirm the superiority of the proposed technique in terms of sensitivity, resolution, computational complexity and cost of the measured SoC in comparison with other existing methods of estimating SoC. This can be a potential method to estimate SoE of the battery as well. </p>

<p>Worldwide concern on fossil fuels depletion and adverse impact on environment pushed researchers to find an alternative energy source. Among various potential systems, electrochemical energy storage devices have attracted significant attraction due to short charge/discharge time, easy relocation, and relatively cheap cost compared to large storage systems. Much research has been reported to suggest a material for electrochemical storage systems. Carbon is a key part of human life in terms of energy source, building materials, daily clothing and foods. The extraordinary characteristics of carbon materials, including good conductivity, good structure stability, relatively low cost, and sustainability, draw interest to carbon application in energy storage systems. </p> <p>The introduction of lithium ion batteries (LIB), using graphite as an anode material, fulfilled the need of alternative energy source and elevated the technologies into next level high-performance applications such as portable devices. While the technology advancement in high performance electronics fosters the development of advanced lithium ion batteries, the introduction of electric vehicles and large intermittent systems seeks energy storage devices with high capacity, sustainability, and low cost. In this thesis, the impact of the characteristics of carbon material on energy storage system performance is studied. The work presented in this thesis not only suggests a cost-effective carbon synthesis for advanced LIB, but also addresses how the carbon structure impact and resolves the systematic issue associated with next generation energy storage systems.</p> <p>Chapter 3 describes a facile, one-step, solvent-free ‘dry autoclaving’ synthesis method utilizing coffee oil as the carbon precursor to obtain micrometer diameter spheroidal carbon particles for lithium ion battery anodes. The spheroidal morphology resulted from the evaporation of liquid oil into a liquid/gas phase interphase at elevated temperature (700 ^oC), followed by solid/gas sublimation interactions during cooling (below 350 ^oC) in a closed autoclave. A mechanism of spheroidal carbon formation is proposed considering the precursor’s composition and chemical interactions during autoclaving. The prepared carbon from dry autoclave has shown successful LIB performance and structure stability after 250 cycles.</p> <p>Chapter 4 illustrates the temperature effect on the structure of biomass derived carbon. In this study, due to its abundance and high porosity, pistachio shells were selected as the primary carbon source and carbonized at a range from 700 to 1500 °C. The temperature effect on carbon structure was analyzed by XRD, Raman, BET, and electron microscopy. To propose an advanced lithium ion battery, pistachio shell-derived carbon was applied as an anode material for a sodium ion battery (SIB). The correlation of carbon structure and SIB electrochemical performance is presented. Pistachio shell carbonized at 1000 °C resulted in highly amorphous structure with specific surface area (760.9 m²/g) and stable cycle performance (225 mAh g^-1 at 10 mA g^-1). With support from Raman, XRD, and BET, the storage mechanism has been studied as well.</p> <p> Chapter 5 describes the impact of carbon structure on resolving the polysulfide shuttling effect in lithium sulfur (Li-S) batteries. Lithium sulfur batteries have received tremendous attention due to its high theoretical capacity (1672 mAh g^-1), sulfur abundance, and low cost. However, main systemic issues, associated with polysulfide shuttling and low Coulombic efficiency, hinder the practical use of sulfur electrodes in commercial batteries. The work in this thesis demonstrated an effective strategy of decorating nano-MnO₂ (less than 10 wt. %) onto a sulfur reservoir in order to further capture the out-diffused polysulfides via chemical interaction, and thereby improve the electrochemical performance of sulfur electrodes without increasing the mass burden of the total battery configuration. Pistachio shell-derived sustainable carbon (PC) was employed as an effective sulfur container due to its structural characteristics (interconnected macro channels and micropores). With the aids of the structural benefits of PC scaffold and the uniform decoration of nano-MnO₂, the polysulfide shuttling effect was significantly suppressed and cycling performance of a sulfur cathode was dramatically improved over 250 cycles.</p> This thesis offers a new prospect in the study of carbon materials applications in various energy storage systems. This concept can be further extended to other applications, such as lithium metal batteries. The intercalation property of carbon structure can reduce the local current density, reducing the risk of lithium dendrite growth, which is the most critical issue of lithium metal battery.

Företaget BlackWing Sweden AB tillverkar ultralätta flygplan av kolfiberkomposit. Företaget vision är att tillverka ett flygplan som helt kan drivas av elektricitet med samma prestanda som flygplan drivet av fossila bränslen. För att kunna driva BlackWing flygplanet med hjälp av elektricitet behövs ett batteripaket, elektronikstyrning samt en elmotor. Därför har detta examensarbete ägnats åt att främst undersöka vilka elmotorer och battericeller som är mest lämpade för BlackWing flygplanet. Därefter togs resultatet fram genom beräkningar på battericeller och motorpaket med hjälp av insamlad information om motor-och batteriprestanda. För att få ett mer objektivt och systematiskt resultat här även en Pugh-matris används för att på ett enkelt sätt avgöra den mest lämpliga battericellen. Resultatet av detta arbete visade sig att i dagsläget är batteriet Envia, High Energi Pouch cell (ENV35011-CRC) och Siemens motor DYNADYN® 85 är mest lämpliga för BlackWing flygplanet. / BlackWing Sweden AB manufactures ultralight aircraft made from carbon fibre composite. The company's vision is to produce an aircraft that can be completely powered by electricity with the same performance as the aircraft powered by fossil fuels. To operate the BlackWing aircraft using electricity it will need a battery pack, electronic controls and an electric driveline. Therefore, this thesis has been devoted primarily to study which electric engine and battery cells that would be most suitable for the BlackWing aircraft. The result was produced by calculations of the battery cells and electric driveline by using collected information about driveline and battery performance. To get a more objective and systematic results, a Pugh matrix was used to easily determine the most suitable battery cell. The results of this work showed that in the current situation, the battery Envia High Energy Drone Cell Pouch (ENV35011-CRC) and Siemens engine DYNADYN® 85 are the most suitable for the BlackWing aircraft.

The objective of this thesis is to investigate how the onboard battery of a quadcopter can be charged through manual rotation of its motors, while understanding the resulting aerodynamical forces acting on the rotors during hover, as well as considering the changes in thrust capabilities when the electronic and structural design are altered. A theoretical approach using the momentum theory will present a general understanding of rotor performance whilst describing the correlation between rotor parameters, thrust and mechanical power. Furthermore, the idea of using the motors as generators are put under study to investigate their electrical output and utilize them to recharge the battery. This is done using the counter electromotive force equation, and a sequence of other equations that will present numerical data of actual manual work converted into electrical power. Resulting in the required time to manually recharge the quadcopter subsequently sustaining hover flight for three minutes. It is concluded in this report that manual recharging of the battery using the motors as generators is possible, as well as maintaining its flying ability in case of added weight. Although not deemed practical in commercial use, it is a new methodology with the intention to develop a sustainable quadcopter further expanding its practical applications in both aviation industry and human aid.