The aim of master’s thesis was to develop a method for long-term measuring the influence of temperature on photovoltaic cells and lithium-polymer batteries and to design such measuring system. System was assembled on universal printed circuit board. It consisted of circuits for measuring temperature, illuminance and charging circuit, which charged battery with capacity 110 mAh. The PV cell BSK-SP9261 was used as source. Voltages was recorded by data acquisition device NI-USB 6009 and loged in program developed in LabVIEW 2012 enviroment. Afterwards, temperature, illuminance, voltage on PV cell and internal resistance of battery were computed.

This diploma thesis deals with battery charging. The thesis describes qualities and possi-bilities of lithium battery charging. The charger is independent on the input voltage and recharges batteries carefully. Due to a careful recharging process it is needed to measure the voltage at various cells of the battery and then balance this voltage. Since the charger is to be implemented in a robot, it is needed to switch the operation from an external source and the battery. The first part of the project deals with qualities of batteries and the way of their recharging. In the second part I design an individual blocks charger. In the third part I deal with a communication with a computer charger and data visualization. And in the last part I designed a program for the charger.

The lithium ion battery is today mainly used in cell phonesand laptops. In the future, this kind of battery might beuseful in hybrid electric vehicles as well. In this work, the main focus has been to gain more knowledgeabout the lithium ion battery in the hybrid electric vehicle(HEV) and more precisely to examine what processes of thebattery that are limiting at HEV currents. Both experiments andmathematical modelling have been used. In both cases, highrate, pulsed currents typical for the HEV, have been used. Two manuscripts have been written. Both of them concern thebehaviour of the battery at HEV load, but from different pointsof view. The first one concerns the electrochemical behaviourof the battery at different ambient temperatures. Theexperimental results of this paper were used to validate amathematical model of a Li-ion battery. Possiblesimplifications of the model were identified. In this work itwas also concluded that the mass transfer of the electrolyte isthe main limiting process within the battery. The mass transferof the electrolyte was further studied in the second paper,where the concentration of lithium ions was measured indirectlyusing in situ Raman spectroscopy. This study showed that themathematical description of the mass transfer of theelectrolyte is not complete. One main reason of this issuggested to be the poor description of the physical parametersof the electrolyte. These ought to be further studied in orderto get a better fit between concentration gradients predictedby experiments and model respectively.

<p>The predicted growth in demand for electric vehicles (EVs) has given rise to increasing use of lithium-ion batteries (LIBs), which are the source of energy used in all EVs. Recycling of spent LIBs not only can supply more materials to manufacturing new LIBs, but also can mitigate haz-ardous waste disposal in the environment. Direct recycling focuses on separating cathode materials to be re-purposed or remanufactured. Delamination of cathode materials is the necessary first step; however, it is fraught with difficulties due to the strong adhesive forces provided by the polyvi-nylidene fluoride (PVDF) binder that is widely used in LIBs. The widely accepted delamination methods are N-Methyl-2-pyrrolidone (NMP) solvent dissolution and direct calcination, which are not desirable due to either environmental and health concerns or high energy consumption.</p> <p>The lithium chemical systems (LiCl, LiNO₃, and LiOH) and their binary eutectic systems, were systematically studied to recover heterogeneous cathode active materials (NMC 111 and LMO) from spent LIBs of EVs. The LiOH-LiNO₃ eutectic system showed 98.3% peel-off effi-ciency under preferable conditions. The recycled products were characterized using ICP-OES, XPS, SEM, and XRD. There were minimal changes in chemical composition, morphology, or crystal structure of the recycled cathode materials after LiOH-LiNO3 eutectic treatment, compared with those recycled with an AlCl₃-NaCl eutectic molten salt treatment that introduces more Al contamination and morphological defects.  </p> <p>In order to avoid corrosive chemicals and minimize particle agglomeration, additional lith-ium salts were investigated, including LiOAc (lithium acetate), Li₂CO₃, and Li₂SO₄. A peel-off efficiency of up to 98.5% was achieved at a LiOAc to LiNO₃ molar ratio of 3:2, salt to cathode mass ratio of 10:1, temperature of 300° C, and a holding time of 30 minutes. To validate the effect of the cations, the recycled products from the molten sodium salt system (NaOAc-NaNO3) were tested. The lithium salt system achieved separation at a lower temperature. Use of LiOAc-LiNO₃ minimized morphological changes compared with direct calcination.</p> <p>The effective separation in LiOH-LiNO3 or LiOAc-LiNO3 molten salt systems was based on promotion of PVDF decomposition, and these two systems may be feasible for recycling other typical cathodes (LCO and LFP) where PVDF is used as the binder. Use of molten lithium salts as alternatives to direct calcination or use of other solvents, may help facilitate recycling of spent LIBs, and even achieve a way for closed loop direct recycling of materials.</p> <p> Additionally, a chemical-free pressure washing system was studied to overcome the adhe-sion provided by PVDF. Although the pressure washing system was not able to remove PVDF from the cathode materials, nearly instant separation from the aluminum backing was achieved when the shear stress and normal stress provided by the impacting of high-pressure waterjet was stronger than the binding forces. Factors investigated included water pressure, distance between the nozzle and cathode, the incident angle of the water jet, and the nozzle type (sprayer angle). A 34-1 fractional factorial design was used to evaluate the parameters and find the optimal operating conditions. A small amount of Al and consistent morphology (of nearly pristine cathode active materials) were detected. Three kinds of recycled cathode materials (NMC&LMO, LCO, and LFP) were used as inputs to investigate a sulfuric acid leaching process, indicating high leaching effi-ciencies (lithium > 90% and cobalt > 85%).</p> <p>The degradation of cathode active materials or PVDF affects the adhesion force between cathode materials layer and Al current collector. Because delamination replies on inactivation of bonding forces provided by PVDF, it is believed that the storage environment (air, O₂ or H_{<strong>2</strong>}O) will affect the performances of delamination to some extent. Three representative methods (direct cal-cination, solvent extraction, and pressure washing system) of delamination were selected to eluci-date the effect from air exposure time. Direct calcination was barely influenced and stably sepa-rated CAMs in terms of peel-off efficiency. The pressure washing system or solvent extraction exhibited high peel-off efficiency using control samples, but the performance regarding either Al contamination or separation efficiency  significantly worsened after long air exposure time. This hypothesis could explain lack of reproducibility of some results in different studies and highlight the importance of strict storage condition of spent LIBs to direct recycling technology. </p> <p>Overall, this thesis examines innovative delamination methods for the development of cost-efficient and environmentally friendly direct recycling of spent LIBs. Application of the eutectic molten lithium salt system (LiOH-LiNO₃ and LiOAc-LiNO₃) or pressure washing system indicates promising benefits to reduce toxic gas emission and energy consumption, and accelerate the cir-cular economy.</p>

The lithium-ion battery is the most preferred choice for energy storage, for example, in electric vehicle batteries and electronic devices. These commonly utilized transition metal-based cathodes and graphite anodes. However, replacing the active materials with organic, redox-active materials is of great interest since these organic batteries are excelling in charging speed and cycling stability. Therefore, in the present thesis, the synthesis and characterization of potential organic electroactive materials, mainly polymers, are investigated. Concerning the structure of the polymers, linear polymers, three-dimensional / crosslinked polymers, as well as dendrimers, were chosen. The electroactive subunits include viologen, imide, triphenylamine, porphyrin, and ferrocene, either as homopolymer or copolymer, as well as active materials like graphene oxide (GO) or electrolytes. The characterization of the structures was performed by means of NMR, FTIR spectroscopy, and elemental analysis. The electrochemical properties of products were investigated by the cyclic voltammetry (CV) technique. Electrodes were prepared by drop-casting a solution of the polymers onto a current collector, and the (dis)charge performance was investigated. To enhance the conductivity of the layers, composites of the polymers with GO were prepared. Since the performance depends on the electrolyte composition, different types of solvents and salts were used and compared. The capacities in a thin film of pure polymers and dendrimers were much smaller than in the composite film with rGO. These performances are based on the molecular self-assembly of polymers and dendrimers on individual GO sheets yielding colloidal polymer/dendrimer@GO and efficient GO/rGO transformation electrocatalyzed by polymers and dendrimers. However, the stability and capacity of some polymers and dendrimers such as P2, P5, P6 and G2 were not optimal in this type of composite film. Moreover, the peak potential in the positive charge range assigned to the nitrogen centre of triphenylamine and porphyrin was found to decrease after the first scan, which is probably due to a dissolution of the film. Therefore different methods were used to composite polymer or dendrimer with GO such as reducing GO before mixing. As noticed that the redox behaviour of amine and ferrocene are reversible, but the stability of radical cation species is not stable in organic solvent after oxidation. Besides the preparation of electrodes by drop-casting, the layer-by-layer process was used by alternate dipping between cationic polymer solution and anionic GO or Poly(sodium p-styerenesulfonate) (PSS) solution. PSS acts as a counter ion for the polymer, which changes the moving species in the electrolyte from anion to cation. As noted that a large cation (TBA+) shows lower capacity compared to small cations (Li+, K+). Apart from the CV, quartz crystal microbalance (QCM) was used to monitor layer growth.

Preparation, structural analysis, and electrochemical performance of a new cathodic battery material, consisting of a nanocomposite of poly(vinylferrocene) (PVFc) (Eox: 0.4 V vs. Ag/AgCl) and reduced graphene oxide (rGO), are described. The nanocomposite shows the highest charge-discharge efficiency (at a rate of 100 A g-1) ever reported for any organic / organomatellic battery material. Remarkably, the composite is “thickness scalable” up to 0.21 mAh cm-2 (770 mC cm−2 at 29 μm film thickness) on a flat surface with > 99% coloumbic efficiency, exhibiting a specific capacity density of 114 mAh g−1. The composite material is binder free and the charge storing material (PVFc) accounts for > 88% of the total weight of the cathodic material. The secret behind such a performance is the electrostatic interaction between the redox polymer in its oxidized state (exhibiting positive charge) and the original filler i.e., graphene oxide (GO) with negative surface charge. This self-assembling step is analyzed by zeta potential measurements, and a modeling study confirms the experimentally found heavy polymer loading on the GO (in aqueous solution). The efficient self-assembly led to composites with high ratio of redox polymer / GO where all polymers are in close contact with GO sheets. The stable colloidal solution was casted on the surface of a flat current collector and the insulating GO was electrochemically transformed to conductive reduced graphene oxide (rGO). The GO / rGO transformation was catalyzed by methyl viologen dichloride (MV++) working as a redox shuttle (solublized in the aqueous electrolyte) and thereby accelerating the electron transfer to GO. Complete GO / rGO transformation and the quantitative ion breathing of the composite are found by means of electrochemical quartz crystal microbalance and electrochemical AFM.

The need for accessible, safe and reliable energy storage solutions has been accentuated, in recent years, due to the shift from fossil to renewable energy sources. In this context, aluminum-based electrochemical systems have emerged as strong candidates for energy storage devices. Despite that, the successful translation from the laboratory and the commercialization of the technology faces critical challenges that must be overcome. This Dissertation explores carbon and carbon-inorganic cathodes for Al-based electrochemical energy storage devices. We start by understanding carbon cathodes in the presence of acidic ionic liquid electrolytes and draw relevant conclusions on how transition metal catalysts affect different facets of the cell's electrochemical performance. Then, we introduce sulfur and draw insights on the origin of poor cycling stability of carbon/sulfur cathodes as well as on how to extend their cycle life. Next, we focus on maximizing the pseudocapacitive contribution of carbons, and thus cathode capacity, through pore size engineering. Finally, we translate our findings to aqueous electrolytes and fabricate, for the first time, a superior rechargeable aluminum-carbon battery cathode by setting forward a hypothesis of a unique charge-storage mechanism.

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The main concerns of air travel are the operating costs of general aviation aircraft. Hybrid-electric system design provides a great opportunity for future aircraft models to be environmentally friendly. The Hybrid-electric power propulsion system experienced a growing interest driven by determined targets. Electric technologies have proven promising success to achieve a successful result in the near- and long-term. Combining fuel cells and batteries, this technology can enable a significant reduction in fuel consumption, noise, and emissions. Different types of fuel cells and batteries are proposed and discussed during this work. The Cessna C-172 is a candidate to test the combination of the most promising fuel cells and batteries for a hybridization or complete electrification strategy.