Using a lithium metal negative electrode may give lithium metal batteries (LMBs), higher specific energy density and an environmentally more benign chemistry than Li-ion batteries (LIBs). This study asses the environmental and cost impacts of in silico designed LMBs compared to existing LIB designs in a vehicle perspective. The life cycle climate and cost impacts of LMBs show a similar pattern: the use phase has more climate and cost impacts than the production phase. As compared to LIBs and with respect to the positive electrode, Lithium Nickel Manganese Cobalt Oxide (NMC) is preferable to Lithium Iron Phosphate (LFP). The cell cost is highly dependent on the cost of lithium metal; a cost reduction of 50% causes a cell cost reduction of 8–22% depending on the choice of positive electrode material and if the cell is optimised for power or energy. For electric vehicle usage, the total cost per km is mainly dependent on the energy consumption per km and the capacity of the positive electrode, representing cost saving potentials of about 10%. These generic results can be used as a base for investigations of other battery technology using lithium metal electrodes.

Ex situ and time-resolved in operando neutron powder diffraction (NPD) has been used to study the structural evolution of the graphite negative electrode and LiFePO4 positive electrode within ANR26650M1A commercial batteries from A123 Systems, in what to our knowledge is the first reported NPD study investigating a 26650-type battery. Batteries with different and accurately-known electrochemical and storage histories were studied, enabling the tell-tale signs of battery degradation to be elucidated using NPD. The ex-situ NPD data revealed that the intensity of the graphite/lithiated graphite (LixC6 or LiyC) reflections was affected by battery history, with lower lithiated graphite (LiC12) reflection intensities typically corresponding to more abused batteries. This indicates that the lithiation of graphite is less progressed in more abused batteries, and hence these batteries have lower capacities. In operando NPD allows the rate of structural evolution in the battery electrode materials to be correlated to the applied current. Interestingly, the electrodes exhibit different responses to the applied current that depend on the battery cycling history, with this particularly evident for the negative electrode. Therefore, this work illustrates how NPD can be used to correlate a battery history with electrode structure.

Annika Ahlberg Tidblad, Helena Berg, Kristina Edström, Patrik Johansson, and Aleksandar Matic 1. Scania CV AB – Materials Technology, Hybrid and Electronics, SE 151 87 Södertälje, Sweden 2. AB Libergreen 3. Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, SE 751 21 Uppsala, Sweden 4. Department of Applied Physics, Chalmers University of Technology, SE412 96 Göteborg, Sweden

Eriksson, R. 2015. Structural Changes in Lithium Battery Materials Induced by Aging or Usage. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1227. 75 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9165-9. Li-ion batteries have a huge potential for use in electrification of the transportation sector. The major challenge to be met is the limited energy storage capacity of the battery pack: both the amount of energy which can be stored within the space available in the vehicle (defining its range), and the aging of the individual battery cells (determining how long a whole pack can deliver sufficient energy and power to drive the vehicle). This thesis aims to increase our knowledge and understanding of structural changes induced by aging and usage of the Li-ion battery materials involved. Aging processes have been studied in commercial-size Li-ion cells with two different chemistries. LiFePO4/graphite cells were aged under different conditions, and thereafter examined at different points along the electrodes by post mortem characterisation using SEM, XPS, XRD and electrochemical characterization in half-cells. The results revealed large differences in degradation behaviour under different aging conditions and in different regions of the same cell. The aging of LiMn2O4-LiCoO2/Li4Ti5O12 cells was studied under two different aging conditions. Post mortem analysis revealed a high degree of Mn/Co mixing within individual particles of the LiMn2O4-LiCoO2 composite electrode. Structural changes induced by lithium insertion were studied in two negative electrode materials: in Li0.5Ni0.25TiOPO4 using in situ XRD, and in Ni0.5TiOPO4 using EXAFS, XANES and HAXPES. It was shown that Li0.5Ni0.25TiOPO4 lost most of its long-range-order during lithiation, and that both Ni and Ti were involved in the charge compensation mechanism during lithiation/ delithiation of Ni0.5TiOPO4, with small clusters of metal-like Ni forming during lithiation. Finally, in situ XRD studies were also made of the reaction pathways to form LiFeSO4F from two sets of reactants: either FeSO4·H2O and LiF, or Li2SO4 and FeF2. During the heat treatment, Li2SO4 and FeF2 react to form FeSO4·H2O and LiF in a first step. In a second step LiFeSO4F is formed. This underlines the importance of the structural similarities between LiFeSO4F and FeSO4·H2O in the formation process of LiFeSO4F.

Aging of power-optimized commercial 2.3 Ah cylindrical LiFePO4//graphite cells to be used in hybrid electric vehicle is investigated and compared for three different aging procedures; (i) using a simulated hybrid electric vehicle cycle within a narrow SOC-range, (ii) using a constant-current cycle over a 100% SOC-range, and (iii) stored during three years at 22 degrees C. Postmortem analysis of the cells is performed after full-cell electrochemical characterization and discharge. EIS and capacity measurements are made on different parts of the disassembled cells. Material characterization includes SEM, EDX, HAXPES/XPS and XRD. The most remarkable result is that both cycled cells displayed highly uneven aging primarily of the graphite electrodes, showing large differences between the central parts of the jellyroll compared to the outer parts. The aging variations are identified as differences in capacity and impedance of the graphite electrode, associated with different SEI characteristics. Loss of cyclable lithium is mirrored by a varying degree of lithiation in the positive electrode and electrode slippage. The spatial variation in negative electrode degradation and utilization observed is most likely connected to gradients in temperature and pressure, that can give rise to current density and potential distributions within the jellyroll during cycling. (C) 2014 Elsevier B.V. All rights reserved.

In this thesis an alternative energy storage system in the drive train of a hybrid electric vehicle is investigated. In particular, it concentrates on the potential reduction of the stresses of the battery when electrochemical capacitors, a.k.a supercapacitors, are added as a high power energy storage. The energy storage system is described and a simplified drive train is simulated in the simulation software MATLAB®/SIMULINK®. Different control strategies are tested and an estimation of the performance is given. With the simulation results at hand, a downscaled HEV drive train consisting of NiMH batteries, electrochemical capacitors, a DC/DC converter and an external load, is built and tested. A comparison between simulated and experimental results is made, in terms of estimated battery stresses and efficiency. The results show a significantly reduction in battery stresses and a good agreement between the models used in simulations and the laboratory system. To further investigate the potential of a battery-electrochemical capacitor system, a full-scale system for a city bus is dimensioned and simulated. This simulation shows that the total weight of the energy storage system could be reduced significantly when batteries are combined with a bank of electrochemical capacitors. Moreover, an increased durability of the battery would be expected by this alternative energy storage system.

The LixMn2O4 to λ-MnO2 phase transition, as lithium is extracted electrochemically from the spinel structure, has been studied by in situ neutron diffraction. The ‘single-phase’ composition around 4.1 V is found to be strongly dependent on potential, with the Li content (x) varying between 0.65(9) and 0.49(12). The amount of Li in the cubic λ-MnO2 phase is 0.27(13) with cell parameter a=8.115(1) Å, in good agreement with earlier ex situ neutron diffraction results. A simple in situ neutron diffraction method is presented for following structural changes during electrochemical cycling of a lithium insertion compound.

Lithium manganate spinels with the formula Li1+xMn2−xO4 undergo lithium↔proton ion exchange to give a defect λ-MnO2 phase which can act as a lithium selective sorbent. The substitution of manganese by other metals, such as Co, Cr, Ti and Ga allow the structural properties of the spinel lattice to be modified and tailored. This work uses neutron diffraction, inelastic neutron scattering, XAFS and atomistic calculations to show that in the non-substituted spinel, inserted protons are present predominantly as hydroxyl groups directed into the vacant 8a site, with an orientation influenced by the presence of manganese vacancies. The influence of cation substitution is explained within this context.

Trends in the electronic structure of the spinel-type manganese oxide Li1 + xMn2 − xO4, 0 ≤ x ≤ 1/4, are studied using the LMTO–ASA method. The stability of the system is discussed in terms of composition (x) and the position of lithium in the structure; the influence of the latter on the total valence energy and the density-of-states (DOS) is also probed systematically. The 'extra' lithium atoms are shown to prefer the octahedral 16d position for x < 2/16, and the octahedral 16c position for higher degrees of substitution. The open-circuit voltage reaches a maximum for x = 1/16.

The structural evolution of LiMn2O4spinel was followed from 320 K down to 10 K. The structural transformation, recently studied down to 230 K [Rodriguez-Carvajal, Rousse, Masquelier & Hervieu (1998).Phys. Rev. Lett.81, 4660–4663], takes place near room temperature with a significant hysteresis: the high-temperature cubic phase transforms to a superstructure orthorhombic cell. The present study indicates that the nuclear structure is stable down to 10 K, while neutron diffraction patterns below 80 K show the rise of a magnetic ordering in the spinel phase. From Mn—O bond-length analysis of the MnO6octahedra, a temperature-independent charge ordering in the structure can be deduced.

Stoichiometric Li1+xMn2-xO4 has been synthesised from LiOH . H2O and manganese(III) acetate. The structure of the compound so formed (Li1+xMn2-xO4, x=0.14) has been refined from neutron powder diffraction data. The sample contained an impurity phase of ca. 5 wt% Li2MnO3. Under these conditions, two-phase Rietveld refinement showed lithium ions to occupy both tetrahedral 8a-sites (100% occupancy) and octahedral 16c-sites (7.0% occupancy); this 16c-site occupation has not been observed previously. Manganese ions occupy octahedral 16d-sites (93.0% occupancy).

LMTO-ASA self-consistent band structure calculations have been performed for the cubic spinel LiMn2O4 and its delithiated and lithiated phases: lambda-MnO2 and Li2Mn2O4. It has been shown that the Jahn-Teller distortion plays a vital role le in the stabilisation of the Li2Mn2O4 phase. The influence on the band structure of different possible positions for the lithium ions is investigated, and the phase transition from cubic to tetragonal symmetry for Li2Mn2O4 discussed. The change in potential associated with the insertion of lithium ions into lambda-MnO2 to form LiMn2O4 and Li2Mn2O4 has been calculated as 1.51 V and 1.16 V, respectively. The lithium atoms are ionised by contributing substantial character to the bonding band. However, the charge transfer is small and the electron density around the lithium ions is higher than in lithium metal.

Partially electrochemically delithiated LiMn2O4 has been studied by a combination of in situ X-ray and ex situ neutron diffraction to help shed further light on structural phenomena in the >4 V range. LixMn2O4 samples were extracted from charged half-cells and their structures refined by the Rietveld method. At ca. 4.1 V, a spinel-phase of composition Li0.74Mn2O4 corresponds to a distinct step in the charging curve, suggestibly related to a Mn3+ (high-spin) to Mn4+ (low-spin) transition. The refined composition for the λ-MnO2 phase at 4.3 V was Li0.28Mn2O4, and showed no evidence of lithium/hydrogen ion-exchange. Electrochemical delithiation to form the λ-MnO2 phase is concluded to involve a single spinel phase and not a coexistence of two-phases.

The structures of deuterated, protonated, and relithiated forms of MnO2 spinel, obtained by ion exchange of Li ions with D or H in a well-crystallized spinel Li1.27Mn1.73O4 compound, have been determined by powder neutron diffraction. Refinements were carried out using the Rietveld method of powder profile analysis in the space group Fd3m. Li ions are removed from both tetrahedral 8a and octahedral 16d sites when Li1.27Mn1.73O4 is contacted with DCl or HCl solution. The neutron diffraction data show that deuterium and hydrogen ions are predominantly incorporated into the crystal as -OD and -OH by bonding to lattice oxygen atoms without any other major change to the MnO2 spinel structure. The -OD and -OH groups are directed into the interstitial space of the 8a tetrahedra, but with an orientation which suggests that the deuteron or proton site is favored for occupation only when the nearest neighbor octahedral 16d site contains no Mn ion. When the protonated compound is contacted with LiOH solution, reinserted Li ions relocate on tetrahedral 8a sites in preference to vacant octahedral 16d sites in the MnO2 framework.

There is a considerable lack of detailed information on the structure of lithiated phases of popular-consensus positive electrode materials for lithium/polymer and lithium-ion/polymer batteries. Having illustrated this phenomenon for the specific cases of LiMn2O4 and V6O13, some suggestions are made to present the problem in a more general context. The need for single-crystal diffraction studies is indicated.

MATERIAL SCIENCEthat a dynamic and flexible synthesis process leads to well-defined phasepme and highly crystalline matelials.Results from cathode matelials contc'lining cln•omium andiron substitution for manganese using diffinction and EXAFS are also repmted.Questions regarding the possible clustering ofMn-or Cr-rich domains will be addressed.