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1.
  • Slawinski, Wojciech Andrzej, 1980, et al. (författare)
  • Neutron Pair Distribution Function Study of FePO4 and LiFePO4
  • 2019
  • Ingår i: Chemistry of Materials. - : AMER CHEMICAL SOC. - 1520-5002 .- 0897-4756. ; 31:14, s. 5024-5034
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron powder diffraction studies of the compounds FePO4 and LiFePO4 are reported. Rietveld refinement of the diffraction data provides averaged structures for both materials that are in good agreement with the published structures. In addition, detailed investigations of the short-range ion-ion correlations within each compound have been performed using the reverse Monte Carlo (RMC) modeling of the total scattering (Bragg plus diffuse) data. Although the short-range structural information for LiFePO4 is consistent with the long-range (averaged) picture, a small, but statistically significant, proportion of the anions is displaced away from their ideal sites within the RMC configurations of FePO4. These anion displacements are discussed in terms of a small concentration of Li+/Fe2+ occupying the empty octahedral sites, probably arising from incomplete delithiation of the LiFePO4 and/or antisite (Li+-Fe2+) defects introduced during the delithiation process.
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2.
  • Edström, Kristina, Professor, 1958- (författare)
  • Battery 2030+ Roadmap
  • 2020
  • Rapport (övrigt vetenskapligt)abstract
    • Climate change is the biggest challenge facing the world today. Europe is committed to achieving a climate-neutral society by 2050, as stated in the European Green Deal.1 The transition towards a climate-neutral Europe requires fundamental changes in the way we generate and use energy. If batteries can be made simultaneously more sustainable, safe, ultrahigh performing, and affordable, they will be true enablers, “accelerating the shift towards sustainable and smart mobility; supplying clean, affordable and secure energy; and mobilizing industry for a clean and circular economy” - all of which are important elements of the UN Sustainable Development Goals.In other words, batteries are a key technology for battling carbon dioxide emissions from the transport, power, and industry sectors. However, to reach our sustainability goals, batteries must exhibit ultra-high performance beyond their capabilities today. Ultra-high performance includes energy and power performance approaching theoretical limits, outstanding lifetime and reliability, and enhanced safety and environmental sustainability. Furthermore, to be commercially successful, these batteries must support scalability that enables cost-effective large-scale production.BATTERY 2030+, is the large-scale, long-term European research initiative with the vision of inventing the sustainable batteries of the future, to enable Europe to reach the goals envisaged in the European Green Deal. BATTERY 2030+ is at the heart of a green and connected society.BATTERY 2030+ will contribute to create a vibrant battery research and development (R&D) community in Europe, focusing on long-term research that will continuously feed new knowledge and technologies throughout the value chain, resulting in new products and innovations. In addition, the initiative will attract talent from across Europe and contribute to ensure access to competences needed for ongoing societal transformation.The BATTERY 2030+ aims are:• to invent ultra-high performance batteries that are safe, affordable, and sustainable, witha long lifetime.• to provide new tools and breakthrough technologies to the European battery industrythroughout the value chain.• to enable long-term European leadership in both existing markets (e.g., transport andstationary storage) and future emerging sectors (e.g., robotics, aerospace, medical devices, and Internet of things)With this roadmap, BATTERY 2030+ advocates research directions based on a chemistry-neutral approach that will allow Europe to reach or even surpass its ambitious battery performance targets set in the European Strategic Energy Technology Plan (SET-Plan)3 and foster innovation throughout the battery value chain.
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3.
  • Kotronia, Antonia (författare)
  • Probing Critical Interfaces in Dual-Ion Batteries : The Road Towards Performant Graphite Cathodes
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Transitioning into a zero-emission society will require massive efforts with respect to the harnessing and storage of renewable energy resources. The development of large-scale, electrochemical energy storage systems based on abundant and environmentally benign compounds is seen upon as a key factor for guaranteeing a successful outcome. On these grounds, research into post lithium-ion battery technologies has become increasingly important. Among emerging concepts is that of dual-ion batteries (DIBs); the operational mechanism of which uses both the cation and anion in the electrolyte. DIBs offer some unique advantages compared to other cell chemistries, owing to the unconventional materials combinations they enable. Graphite versus graphite cells constitute a cell chemistry which results in high average voltage (> 4.5 V), decent specific capacity (~100 mAh g-1) and which eliminates transition metals from the cathode. Despite considerable merits, graphite versus graphite dual-ion cells have proven difficult to realize, mainly due to the instability of the cathode electrolyte interface (CEI) at high potentials. This thesis explores critical interfaces in both Li- and K-based DIBs and considers strategies to mitigate these instabilities, based on a combination of electrode and electrolyte engineering. The influence of the electrolyte salt and solvent on the CEI is studied through electrochemical characterization methods and X-ray photoelectron spectroscopy (XPS). Conventional LiPF6-based electrolytes are contrasted to formulations using high concentrations of lithium imide salts such as lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The impact of incorporating functional additives and precycling protocols to reduce electrochemical irreversibility is discussed for Li4Ti5O12‑graphite and MoS2-graphite cells tailored for Li- and K-based DIBs, respectively. In addition, a ternary ionogel is introduced as a novel electrolyte platform for DIBs due to its promising ionic conductivity, oxidative stability and mechanical properties. Finally, the impact of different electrode binders on the surface chemistry and electrochemical performance of the graphite cathode is elucidated. In summary, this work indicated that a passivating, anion conducting CEI is key to enabling dual-ion batteries. Despite the cumbersome nature of this task, ways forward were highlighted both in terms of concrete examples, such as the construction of DIBs incorporating functional additives (e.g. triallyl phosphate) and binders (e.g. poly(vinylidene fluoride-co-hexafluoropropylene)), and in terms of methodology, including the design of reliable cycling protocols to evaluate DIB-performance.
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4.
  • Källquist, Ida (författare)
  • Interfaces in Li-ion batteries seen through photoelectron spectroscopy
  • 2019
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • To accommodate the need for greener energy solutions renewable energy sources aswell as reliable energy storage is a prerequisite. For the latter, high energy densitybatteries with long-term cycling stability are necessary. The cycling properties of abattery is to a large extent dependent on the functionality of the battery interfaces. Assuch, there is a need to understand the reactions occurring between the electrode andelectrolyte, and to limit those that are detrimental to the battery performance. Thetopic of this thesis is these interfaces in Li-ion batteries seen through photoelectronspectroscopy (PES).PES is due to its surface and chemical sensitivity one of the most suitable techniquesto study battery interfaces. In this thesis, PES is used to follow the oxidationstate and chemical environment of different atoms to understand the reactions occurringin the battery. This work uses a combination of soft and hard X-ray photoelectronspectroscopy as well X-ray absorption spectroscopy (XAS) to investigate the degradationmechanisms in high energy density cathode materials. The materials investigatedare in the class of Li-rich disordered rock-salts (DRS) and provide very highinitial capacities, but unfortunately lacks in cycling stability. In this thesis it is shownthat the reason for this is an unstable surface, possibly related to the occurrence ofanionic redox in the material, leading to breakdown of both electrolyte and electrodematerial. In addition, it is shown that the interface stability can be improved by choosingtransition metals that promotes the DRS structure and thus increases the chemicalstability of the material and long term cycling of the battery.Even though ex situ measurements provide many insights into the properties ofbattery interphases, there is still a need for operando measurement to completely answerthe puzzling question of their full functionality. In this thesis first steps towardsoperando measurements are taken by identifying the measurements conditions necessaryto probe a battery electrolyte with ambient pressure photoelectron spectroscopy(APPES) and a thorough characterization of a typical battery electrolyte is performed.The results show that the liquid can be stabilized by using the solvent as ambient gas,and also that care should be taken to avoid radiation damage when synchrotron lightis used. For the electrolyte characterization it is shown that a salt enrichment of particularlyLi+ and ionic fluoride is found at the droplet surface. These results are crucialto be able to single out contributions from the interphase in future operando measurements.When the method of operando APPES has matured and can be performed routinely,this could possibly be the key needed to understand how the interfaces in batteriescan be controlled to unlock the potential of stable high capacity materials infuture batteries.
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5.
  • Meng, Qijun, et al. (författare)
  • Efficient BiVO4 Photoanodes by Postsynthetic Treatment : Remarkable Improvements in Photoelectrochemical Performance from Facile Borate Modification
  • 2019
  • Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 58:52, s. 19027-19033
  • Tidskriftsartikel (refereegranskat)abstract
    • Water-splitting photoanodes based on semiconductor materials typically require a dopant in the structure and co-catalysts on the surface to overcome the problems of charge recombination and high catalytic barrier. Unlike these conventional strategies, a simple treatment is reported that involves soaking a sample of pristine BiVO4 in a borate buffer solution. This modifies the catalytic local environment of BiVO4 by the introduction of a borate moiety at the molecular level. The self-anchored borate plays the role of a passivator in reducing the surface charge recombination as well as that of a ligand in modifying the catalytic site to facilitate faster water oxidation. The modified BiVO4 photoanode, without typical doping or catalyst modification, achieved a photocurrent density of 3.5 mA cm(-2) at 1.23 V and a cathodically shifted onset potential of 250 mV. This work provides an extremely simple method to improve the intrinsic photoelectrochemical performance of BiVO4 photoanodes.
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6.
  • Mussa, Abdilbari Shifa, et al. (författare)
  • Fast-charging effects on ageing for energy-optimized automotive LiNi1/3Mn1/3Co1/3O2/graphite prismatic lithium-ion cells
  • 2019
  • Ingår i: Journal of Power Sources. - : ELSEVIER SCIENCE BV. - 0378-7753 .- 1873-2755. ; 422, s. 175-184
  • Tidskriftsartikel (refereegranskat)abstract
    • The reactions in energy-optimized 25 Ah prismatic NMC/graphite lithium-ion cell, as a function of fast charging (1C-4C), are more complex than earlier described. There are no clear charging rate dependent trends but rather different mechanisms dominating at the different charging rates. Ageing processes are faster at 3 and 4C charging. Cycling with 3C-charging results in accelerated lithium plating but the 4C-charging results in extensive gas evolution that contribute significantly to the large cell impedance rise. Graphite exfoliation and accelerated lithium inventory loss point to the graphite electrode as the source of the gas evolution. The results are based on careful post-mortem analyses of electrodes using: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). SEM results show particle cracking independent of the charging rate used for the cycling. XPS and EIS generally indicate thicker surface film and larger impedance, respectively, towards the edge of the jellyrolls. For the intended application of a battery electric inner-city bus using this type of cell, charging rates of 3C and above are not feasible, considering battery lifetime. However, charging rates of 2C and below are too slow from the point of view of practical charging time.
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7.
  • Nilsson, Viktor, 1985- (författare)
  • Highly Concentrated Electrolytes for Lithium Batteries : From fundamentals to cell tests
  • 2018
  • Licentiatavhandling (övrigt vetenskapligt)abstract
    • The electrolyte is a crucial part of any lithium battery, strongly affecting longevity and safety. It has to survive rather severe conditions, not the least at the electrode/electrolyte interfaces. Current commercial electrolytes based on 1 M LiPF 6 in a mixture of organic solvents balance the requirements on conductivity and electrochemical stability, but they are volatile and degrade when operated at temperatures above ca. 70°C. The salt could potentially be replaced with e.g. LiTFSI, but corrosion of the aluminium current collector is an issue. Replacing the graphite negative electrode by Li metal for large gains in energy density challenges the electrolyte further by exposing it to freshly deposited Li, leading to poor coulombic efficiency (CE) and consumption of both Li and electrolyte. Highly concentrated electrolytes (up to > 4 M) have emerged as a possible remedy, by a changed solvation structure such that all solvent molecules are coordinated to cations – leading to a lowered volatility and melting point, an increased charge carrier density and electrochemical stability, but a higher viscosity and a lower ionic conductivity.Here two approaches to highly concentrated electrolytes are evaluated. First, LiTFSI and acetonitrile electrolytes with respect to increased electrochemical stability and in particular the passivating solid electrolyte interphase (SEI) on the anode is studied using electrochemical techniques and X-ray photoelectron spectroscopy. Second, lowering the liquidus temperature by high salt concentration is utilized to create an electrolyte solely of LiTFSI and ethylene carbonate, tested for application in Li metal batteries by characterizing the morphology of plated Li using scanning electron microscopy and the CE by galvanostatic polarization. While the first approach shows dramatic improvements, the inherent weaknesses cannot be completely avoided, the second approach provides some promising cycling results for Li metal based cells. This points towards further investigations of the SEI, and possibly long-term safe cycling of Li metal anodes.
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8.
  • Renman, Viktor, et al. (författare)
  • Manganese pyrosilicates as novel positive electrode materials for Na-ion batteries
  • 2018
  • Ingår i: Sustainable Energy & Fuels. - 2398-4902. ; 2:5, s. 941-945
  • Tidskriftsartikel (refereegranskat)abstract
    • A carbon-coated pyrosilicate, Na2Mn2Si2O7/C, was synthesized and characterized for use as a new positive-electrode material for sodium ion batteries. The material consists of 20-80 nm primary particles embedded in a approximate to 10 nm-thick conductive carbon matrix. Reversible insertion of Na+ ions is clearly demonstrated with approximate to 25% of its theoretical capacity (165 mA h g(-1)) being accessible at room temperature at a low cycling rate. The material yields an average potential of 3.3 V vs. Na+/Na on charge and 2.2 V on discharge. DFT calculations predict an equilibrium potential for Na2Mn2Si2O7 in the range of 2.8-3.0 V vs. Na+/Na, with a possibility of a complete flip in the connectivity of neighboring Mn-polyhedra - from edge-sharing to disconnected and vice versa. This significant rearrangement in Mn coordination (approximate to 2 angstrom) and large volume contraction (>10%) could explain our inability to fully desodiate the material, and illustrates well the need for a new electrode design strategy beyond the conventional down-sizing/coating procedure.
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9.
  • Ahlberg Tidblad, Annika, et al. (författare)
  • Future Material Developments for Electric Vehicle Battery Cells Answering Growing Demands from an End-User Perspective
  • 2021
  • Ingår i: Energies. - 1996-1073 .- 1996-1073. ; 14:14
  • Forskningsöversikt (refereegranskat)abstract
    • Nowadays, batteries for electric vehicles are expected to have a high energy density, allow fast charging and maintain long cycle life, while providing affordable traction, and complying with stringent safety and environmental standards. Extensive research on novel materials at cell level is hence needed for the continuous improvement of the batteries coupled towards achieving these requirements. This article firstly delves into future developments in electric vehicles from a technology perspective, and the perspective of changing end-user demands. After these end-user needs are defined, their translation into future battery requirements is described. A detailed review of expected material developments follows, to address these dynamic and changing needs. Developments on anodes, cathodes, electrolyte and cell level will be discussed. Finally, a special section will discuss the safety aspects with these increasing end-user demands and how to overcome these issues.
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10.
  • Aktekin, Burak, et al. (författare)
  • Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO) : In Situ Neutron Diffraction and Performance in Li Ion Full Cells
  • 2019
  • Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 2:5, s. 3323-3335
  • Tidskriftsartikel (refereegranskat)abstract
    • Lithium ion cells utilizing LiNi0.5Mn1.5O4 (LNMO) as the positive electrode are prone to fast capacity fading, especially when operated in full cells and at elevated temperatures. The crystal structure of LNMO can adopt a P4(3)32 (cation-ordered) or Fd (3) over barm (disordered) arrangement, and the fading rate of cells is usually mitigated when samples possess the latter structure. However, synthesis conditions leading to disordering also lead to oxygen deficiencies and rock-salt impurities and as a result generate Mn3+. In this study, in situ neutron diffraction was performed on disordered and slightly Mn-rich LNMO samples to follow cation ordering-disordering transformations during heating and cooling. The study shows for the first time that there is not a direct connection between oxygen release and cation disordering, as cation disordering is observed to start prior to oxygen release when the samples are heated in a pure oxygen atmosphere. This result demonstrates that it is possible to tune disordering in LNMO without inducing oxygen deficiencies or forming the rock-salt impurity phase. In the second part of the study, electrochemical testing of samples with different degrees of ordering and oxygen content has been performed in LNMO vertical bar vertical bar LTO (Li4Ti5O12) full cells. The disordered sample exhibits better performance, as has been reported in other studies; however, we observe that all cells behave similarly during the initial period of cycling even when discharged at a 10 C rate, while differences arise only after a period of cycling. Additionally, the differences in fading rate were observed to be time-dependent rather than dependent on the number of cycles. This performance degradation is believed to be related to instabilities in LNMO at higher voltages, that is, in its lower lithiation states. Therefore, it is suggested that future studies should target the individual effects of ordering and oxygen content. It is also suggested that more emphasis during electrochemical testing should be placed on the stability of samples in their delithiated state.
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