Lithium-ion Battery Research Research Articles

Investigation on Safety Evaluation of Lithium-Ion Battery

With the wide application of lithium battery, its safety performance is particularly important. Lithium battery short circuit test is typical of battery safety performance test project. Therefore, based on the lithium iron phosphate-graphite system square aluminum shell cylindrical battery, battery, liquid flexible packaging and 18650 as test samples. Study the short circuit test of the three batteries, battery test methods of short circuit test is given and the test results when performing a short-circuit test project risk and failure mechanism. Studies have shown that standards and evaluation methods of the safety of the lithium battery research, has very important practical significance.

Impressive lithium storage properties of layered sodium titanate with hierarchical nanostructures as anode materials for lithium-ion batteries

Ti-based oxides have been considered as a kind of attractive alternative to current carbon anodes due to they are denser and do not impose a cost penalty, as well as have better overcharge protection, thus have attracted extensive attention for use as potential lithium-ion battery anodes. But, the preparation of high capacity, good power and low-cost Ti-based oxide anode materials is still a challenge in lithium-ion battery research field. Herein, a hierarchical structure of layered Na2Ti2O5 (NTO) nanoparticles constructed by petal-shaped nanosheets (NTO-2h) has been reported as anode materials for lithium-ion batteries for the first time. As a result, the as-prepared NTO-2h exhibits superior lithium storage performance, in term of high capacity, good power and ultra-long life. A capacity of 223.8 mAh g−1 can be obtained after 600 cycles at 50 mA g−1, as well as the coulombic efficiencies exceed 99%. More impressively, a capacity of 164.3 mAh g−1 can be retained even after 5000 cycles at a high rate of 1000 mA g−1, showing good power and ultra-long life. Comparing with other as-prepared two control samples, it is found that the electrochemical performances of as-prepared Na2Ti2O5 are heavily dependent on their hierarchical structures. In addition, it is suggested that thus impressive performance, wide availability and low cost may make the Na2Ti2O5 with well-designed structures comparable with conventional TiO2 and Li4Ti5O12, and a promising anode materials for lithium-ion batteries.

Electrothermal impedance spectroscopy as a cost efficient method for determining thermal parameters of lithium ion batteries: Prospects, measurement methods and the state of knowledge

Current lithium-ion battery research aims in not only increasing their energy density but also power density. Emerging applications of lithium-ion batteries (hybrid electric vehicles, plug-in hybrid electric vehicles, grid support) are becoming more and more power demanding. The increasing charging and discharging power capability rates of lithium-ion batteries raises safety concerns and requires thermal management of the entire battery system. Moreover, lithium-ion battery's temperature influences both battery short term (capacity, efficiency, self-discharge) and long-term (lifetime) behaviour. Thus, thermal modelling of lithium-ion battery cells and battery packs is gaining importance. Equivalent thermal circuits' models have proven to be relatively accurate with a low computational burden for the price of low spatial resolution; nevertheless, they usually require expensive equipment for parametrization. Recent research initiated by Barsoukov et al. proposed electrothermal impedance spectroscopy as a novel and non-destructive method of characterizing the thermal properties of batteries by defining frequency dependent thermal impedance. Despite its usefulness, the electrothermal impedance spectroscopy method can be still improved in terms of e.g. accuracy and measurement time and it has a potential to be extended to new applications. Performed review indicates that the electrothermal impedance spectroscopy is a very promising, non-destructive, simple and especially cost-efficient method for thermal characterization of batteries. The scientific intention of this paper is to collect and systematize the state of knowledge about electrothermal impedance spectroscopy and present different measurement methods on the example of a high-power lithium battery cell and finally to discuss the prospect.

Challenges and Issues Facing Lithium Metal for Solid State Rechargeable Batteries

Research on lithium metal combined with polymer electrolyte in lithium rechargeable batteries was started in 1979. Since that time, lithium battery research has expanded worldwide. Several new polymers, solid electrolytes and ionic liquids with improved conductivity were identified. These advances resulted from a better understanding of the major parameters controlling ion migration, such as favorable polymer structure, phase diagrams between solvating polymers and lithium salts, and the development of new lithium counter-anions. In spite of the progress so far, the quest for a highly conductive dry polymer at room temperature is still not available. However, effort is continuing, and all-lithium polymer battery (LPB) developers presently face the challenge of whether to heat the polymer electrolyte to enable high-power performance, as required for electric vehicles and energy storage. LPB developers have explored both the high-temperature and low-temperature options. The commercial use of lithium metal/polymer batteries has been delayed because of the adverse effects of dendrites on the surface of the lithium electrodes, and the difficulty in finding a polymer that has both the mechanical strength and ionic conductivity required in a solid electrolyte. However, recent strategies have emerged to overcome these difficulties, and now these batteries are currently an option for different applications, including electric cars.In this presentation, we review these strategies and discuss the different promising routes that should result in further progress on lithium metal/polymer batteries in the near future. This presentation also discusses the challenges and opportunities in developing thin lithium negative electrodes with stable SEI layers for three battery technologies using: All solid-state Li-sulfur batteries Rechargeable lithium batteries containing dry polymer and ionic liquid-polymer electrolytes 3. Li-air batteries. In addition, we will discuss the safety of lithium, dendrite mechanism, interface phenomena, side reactions, protection of lithium metal, and lithium alloys that are relevant to lithium batteries. Acknowledgement: The author thanks the SCE IREQ and LTE Shawinigan teams for helpful discussion.

Li/Vacancy Configurations in Surface Region of Li2−X MnO3 Cathode Material: A High-Throughput Computational Investigation

Li-rich materials Li2MnO3-LiMO2 (M = Co, Ni, Mn) have received a great deal of research attention due to their attractive properties of high reversible capacity and energy density as lithium-ion battery (LIB) cathodes. Unfortunately, the commercialization of the materials has been hindered by numerous technical issues and challenges, notably the lack of clear understanding of the mechanism causing charge and discharge irreversibility. For understanding the mechanism, a lot of effort has been put into examining the irreversible deterioration of Li2MnO3, for instance in [1] by analyzing the effect of the lithium diffusion, the oxygen deficiency, and other factors on structural evolution and charge compensation. However, most previous works mainly focused on bulk cathode materials, while the surface region is also expected to remarkably affect the electrochemical activities of the materials. In this regard, the link between stable Li/vacancy configurations and Li concentration in the surface region is therefore essential for understanding the electrochemical properties and behavior of the surface region during charge and discharge. On the other hand, high-throughput computational materials design has emerged as a powerful and promising approach for the discovery and comprehensive analysis of materials [2]. Examples for LIB research include [3], where 515 stable lithiation reactions of some selected anode materials were enumerated based on a calculated energy data set of 291 compounds. Recently, the relationship between voltage and safety of LIBs was investigated using 1,400 cathode materials in an identical high-throughput fashion [4]. In this work, we exhaustively examine the relationship between electrochemically stable Li/vacancy configurations and their corresponding voltage in the surface region of Li2MnO3 in the solid-state Li2MnO3-LiMO cathode material through high-throughput computing. Figure 1 shows the slab model of Li2MnO3 (010) with the equivalent cell of Li16Mn8O24 used in this study. For each x in Li2−x MnO3, where 0.0 ≤ x ≤ 2.0 indicating that up to all of 16 Li atoms are subjected to removal, all possible placements of the remaining Li atoms in the lattice are considered, and the total energies of the resulting Li/vacancy structures are calculated, based on which the ground-state Li/vacancy structure is determined. Exploring all possible values of x for up to 16 Li atoms requires 216= 65,536 structures to be calculated and examined. With the aim of enabling the full exploration of such a large search space, we have developed our own software tool for high-throughput density functional theory (DFT) calculations that can effectively and reliably handle concurrent task executions, task and data management, and parameter optimization on a couple of different computing platforms. The calculations are performed by our tool utilizing the OpenMX code [5] as the DFT engine, with the spin-polarized GGA+U scheme having the Hubbard U value of Mn set at 5 eV to account for the strong correlation effect, the PBE functional, an energy cutoff of 300 Ry, and a k-point mesh of 3x3x1. Figure 2 presents several preliminary results showing the voltage profile with respect to x in the Li2−x MnO3 (010) surface region. As can be seen from the figure, although the voltage of the Li2−x MnO3 surface region tends to increase from about 4 V to 5 V with an increase in x where 0.0 ≤ x ≤ 0.5, it converges at around 5 V where 0.5 ≤ x ≤ 2.0. This voltage difference is found to be quite considerable in comparison with that of about 0.05 V in [1], which also observed a similar trend of voltage gain with an increase in x in the bulk Li2-x MnO3 (0.0 ≤ x ≤ 1.0). As a result, the link between voltage and x in the surface region is far more obvious than that in the bulk when the depth of charge is shallow. We will thoroughly analyze and report our latest findings based on a complete coverage of x in the presentation. Acknowledgement The calculations in this work were partly performed using the K computer at the RIKEN Advanced Institute for Computational Science.

Evaluation of Si-Based Cells and the Importance of Scale-up

Automotive target metrics, which include specific and volumetric energy and power densities, are difficult to assess for many bench-scale materials. Thus, in order to identify the most promising technologies for future EV applications, it is crucial that researchers pursue scale-up to, in the least, a “pilot fab” scale that enables larger format cells and more relevant metric assessment. Several key processing differences have emerged during Ford’s scale-up operations involving advanced lithium ion battery research, affecting every fabrication step, including mixing, coating, drying, calendaring, and cell assembly. Processing, in turn, affects key electrode characteristics like slurry formulation, active loading, density, adhesion, uniformity, and repeatability. In every case, scale-up improves processing and the associated electrode characteristics. Certain metrics are also very challenging to measure at small scales, including energy and power densities, effects of cell abuse, calendar life, electrolyte consumption, and volume expansion. This is detailed further with a silicon anode case study.

Redox Species-Based Electrolytes for Advanced Rechargeable Lithium Ion Batteries

Seeking high-capacity cathodes has become an intensive effort in lithium ion battery research; however, the low energy density still remains a major issue for sustainable handheld devices and vehicles. Herein, we present a new strategy of integrating a redox species-based electrolyte in batteries to boost their performance. Taking the olivine LiFePO4-based battery as an example, the incorporation of redox species (i.e., polysulfide of Li2S8) in the electrolyte results in much lower polarization and superior stability, where the dissociated Li+/Sx2– can significantly speed up the lithium diffusion. More importantly, the presence of the S82–/S2– redox reaction further contributes extra capacity, making a completely new LiFePO4/Li2Sx hybrid battery with a high energy density of 1124 Wh kgcathode–1 and a capacity of 442 mAh gcathode–1. The marriage of appropriate redox species in an electrolyte for a rechargeable battery is an efficient and scalable approach for obtaining higher energy density storage devices.

Core-Shell Structured o-LiMnO2@Li2CO3 Nanosheet Array Cathode for High-Performance, Wide-Temperature-Tolerance Lithium-Ion Batteries.

To develop a high-capacity, high-rate, cycle-stable cathode material has long been the focus for lithium-ion battery (LIB) research. Recently, layer-structured orthorhombic-LiMnO2 (o-LMO) has attracted extensive interest owing to its large discharge capacities. However, poor cycle performance greatly hinders its practical application, especially at high temperatures. Conventional strategies to address this issue often lead to sacrificed rate performance and mostly work at low temperatures. Herein, we report a novel core-shell structured, o-LiMnO2@Li2CO3 (o-LMO@Li2CO3) nanosheet array cathode, where the Li2CO3 shell improves cycle performance by preventing o-LMO dissolution in the electrolyte (even at an elevated temperature), the o-LMO core provides high capacities and the nanosheet array architecture ensures rate performance (to the best of our knowledge, this o-LMO nanosheet array architecture is reported for the first time). The above features work synergistically to give well-balanced cycle performance (79% capacity retention at 60 °C, 400 cycles), capacity (207 mAh g(-1) at 0.5C) and rate performance (128 mAh g(-1) at 5C) of the o-LMO@ Li2CO3 cathode as well as remarkable full-cell performance (∼67% capacity retention for 400 cycles at ∼2C, 60 °C). Our work demonstrates that the synergistic effect between the o-LMO core, Li2CO3 coating and the nanoarray structure is an effective strategy for developing high-energy/power density, high-stability LIB cathodes.

Electrochemical Approach to Investigate the Electrolyte Wetting Process of Lithium-Ion Cells

Expanding life time as well as lowering production costs of a lithium-ion cell are two important subjects, which are addressed in the current research of lithium-ion batteries. One approach to reach these aims is an optimization of the electrolyte filling and formation process of the lithium-ion cells. This process steps have a major contribution to the production costs, since it requires high investments to provide a sufficient amount of formation equipment. Furthermore, since this processes can take up to 3 weeks, quite a lot of stock capacity is necessary [1]. After filling the cell with electrolyte, the formation process starts with different aging and charging steps with different durations, charging conditions (e.g. c-rate, voltage cut-off) and atmosphere conditions (e.g. pressure and temperature profiles). The aging steps during the formation process are applied to ensure a proper saturation of all the pores of the electrodes with electrolyte. This is of particular importance for graphite based anodes since a SEI film is built on the graphite particles during the charging steps, which greatly influences the cell’s specific values (e.g. lifetime and safety) [2]. To ensure a good and homogenous quality of the SEI film, there should be no significant amount of electrolyte-dry graphite particles, when the first charging step is applied to the cell. So it’s of relevant importance, to know when this state is reached. Commonly, the optimization of the formation process is an empirical process. For a systematical optimization of the formation process of lithium ion cells, amongst others, a detailed knowledge of the electrolyte wetting process is necessary. First of all, the wetting process is of course greatly influenced by the choice of the materials of the cell components (primarily electrodes and separator) and material parameters (e.g. porosity and torosity). The wettability of single components can be evaluated by tracking the wetting progress of individual components visually or with gravimetric techniques, but there is no generally established test [3]. Beside, since the interface between electrodes and separator has a strong influence on the electrolyte wetting behavior, findings about the wettability of the individual components are not easily transferable to the wetting behavior in a full cell geometry. Furthermore the cell geometry itself has a great impact to the electrolyte wetting behavior, since it can favor or limit the electrolyte supply to the edges of the cell and as a consequence the wetting speed within the cell. This is of particular importance for bigger cell designs (e.g. PHEV 1). Based on electrochemical measurements we propose a novel method, which is performed in situ, to investigate the electrolyte wetting process in lithium-ion full cells. The experiments were executed with a modified pouch-bag cell design enabling us to initiate electrical measurement simultaneous to the start of the filling process under controlled conditions in a climate chamber. The reliability of the method is demonstrated by investigating the electrolyte wetting behavior of cells with different commercially available separators, including polyolefin, ceramic and ceramic coated polyolefin separators. Measurements on the separator by visual methods were executed to validate our novel electrochemical method. To demonstrate the potential of the method, the influence of temperature conditions during the wetting process was investigated. By using the method the wetting speed and degree can be measured in situ on full cell level for the first time. In this presentation, the method’s principals will be presented and the results will be discussed. Furthermore the potential of this method will be illustrated, for example, how and which modification of the components can be realized and how they can help to optimize the electrolyte wetting behavior of lithium-ion cells.

Progress in surface coating on LiNi<sub>0.8</sub>Co<sub>0.15</sub>Al<sub>0.05</sub>O<sub>2</sub> cathode materials for lithium-ion batteries

Cathode materials with high energy density and long life are currently the focus in the research and development of advanced lithium-ion batteries. Compared to traditional commercial layered LiCoO2, the nickel-rich cathode material with typical composition of LiNi0.8Co0.15Al0.05O2 (NCA) has attracted intensive interest because of advantages of low cost and high specific capacity (i.e., ~200 mAh/g). However, this promising cathode material suffers from problems, such as severe irreversible capacity loss and poor performance at high temperature due to the mixed cation distribution of Li/Ni and the presence of high-valent Ni on charge that poses structural instability and strong oxidizing ability. There are generally two strategies to address the issues, namely, cation doping and the more extensively employed surface coating. In this article, we review recent progress made in surface coating of NCA cathode materials. Currently, the materials used for coating NCA mainly include carbonaceous materials (e.g., graphene), oxides and composite oxides (e.g., SiO2, CeO2, TiO2, and Li2O-2B2O3), fluorides (AlF3), lithium-containing compounds (e.g., LiCoO2), phosphates (e.g., AlPO4 and Co3(PO4)2) and polymers (e.g., polyaniline). The surface-coated NCA shows better cycling performance as compared to the raw material. The effect of coating on electrode properties varies among different coated materials. The coating of oxides/fluorides/phosphates reduces the corrosion of electrolyte on the electrode and suppresses the side reaction between the electrolyte and the electrode, giving rise to better capacity retention. Carbonaceous materials and composite oxides exert similar protective effect and help to improve the electrical and ionic conductivity. Some stable lithium-containing compounds are coated on NCA to form a core-shell structure, facilitating both Li+ insertion/delithiation and electron conduction with reduced electrode polarization and enhanced electrode stability. The coating methods also affect the electrode performance. Coating can be achieved through mechanical or chemical ways. The former is to mechanically mix the coating material and the raw NCA material by stirring or milling. Mechanical coating is simple in processing but is energy consuming and may incur structural/morphological break. Chemical coating is to generate in situ the coated material on the surface of raw material via chemical reactions. Complicated procedures are often required to make the coating layer uniformly distributed on target materials. As the coated materials are generally electrochemically inactive, their amount should be kept minimized to reduce expense of available capacity. Additionally, the type of coated materials and the thickness of coating layer should be optimized to make full advantage of coating. As a result of surface modification, the cyclability and thermal stability of NCA cathode materials can be greatly improved as compared to the pristine uncoated electrode.

Beyond Electrochemical Lithium Ion Battery Characterization. Correlation of Chemical and Microstructure Analysis, a Unique Pathway for Studying Performance Characteristics and Failure Mechanisms

Introduction: Lithium ion batteries (LIB) are considered to be a promising solution for various energy storage applications owing to their high energy density. These batteries have grown in popularity in recent years and are often found integrated into portable electronic devices and electric vehicles. In order to support adoption of LiBs for future applications, the formation, operation, and failure properties must be understood. By designing appropriate battery microstructures, reports have indicated that the charge-discharge characteristics of the battery cell may be controlled. Methods: This requires a coupled approach of chemical and structural fabrication with image-based and analytical characterization, in order to both design and validate a particular cell geometry model. Image-based characterizations have recently demonstrated some unique abilities to support LIB research, owing to advancements in single imaging instruments as well as correlative microscopy workflows. While scanning electron microscopy (SEM) reveals information about aging effects of for example grains on a micro and nanometer scale, Raman spectroscopy is the tool of choice when it comes to organic and inorganic material identification. ZEISS has worked closely with approved Raman suppliers to integrate the Raman system into the SEM. Experiment: Two cylindrical batteries type 18650 have been used for the examinations. One cell is shown in its initial condition (new) the other cell was cycled at 25 °C with 8 °C over 480 cycles resulting in a SOH (state of health) of approximately 64 %. The cells were discharged and cut open in a glove box under protective Argon atmosphere. Subsequently the electrode foils were separated, washed in DMC and dried. Small samples were cut from the electrodes and the separator. The samples were mounted in resin. A mechanical preparation by grinding and polishing was used to create the cross sections of the electrodes. Results: In this study, EDX images showed that the cathode contains of two different active materials: one Mn-rich phase which can be identified as LiMn2O2 and a Co,Ni-rich phase with the approximate stoichiometry of LiNi0.33Co0.33Mn0.33O2 (NCM111). Another observation is the formation of cracks within the active material particles of the cycled electrode. Those cracks are presumably due to volume changes occurring during intercalation/deintercalation of lithium and the subsequent evolution of stress and strain inside the cathode material grains. The measured anode thickness difference was approximately 18 % and the measured cathode thickness changed by 7 %. The crumbling of particles normally leads to contact loss between particles and between particles and current collector, thus increasing impedance. While EDX measurements revealed information about the existing elements and metals, Raman spectroscopy is not able to detect metals but adds information about elements below Z=4 (H, He, Li, Be) and organic as well as inorganic material. In this study, Raman spectroscopy was used to distinguish between different polymers, carbon modifications as well as cathode materials like LiMn2O or LiCoO2. In addition the homogeneity of binder material was investigated. Raman micrographs were overlaid on the SEM data , showing the multi-phase composition of the anode as containing graphite (bright blue) and amorphous carbon (dark blue). Furthermore, by extending this characterization to the other layers, two different polymers were identified within the separator and the cathode was identified as Li(Mn,Ni,Co)O2. The most impressive results were changes in the trilayer separator of polypropylene(PP)/polyethylene(PE / polypropylene(PP). The comparison of the separator in a new and cycled battery element revealed a change of the orientation of the PP chains molecule orientation in the polypropylene. While the new battery consisted of uniaxial polypropylene, the old battery is of bi-axial polypropylene. The molecule orientation changes the properties of polypropylene in various ways. Polymers, by definition, are long chain molecules in which the atoms are bound to one another by means of strong covalent bonds. High strength and stiffness values in the chain direction are expected since the applied load would then be opposed by the covalent bond themselves. Most of the commercial polymers exhibit strength and stiffness values far below their theoretical limits. To improve these mechanical properties for example highlychain extended/oriented polymers are manufactured. Biaxial polypropylene can be stretched at lower temperatures compared to uniaxial polypropylene. And because of the biaxial orientation, good mechanical properties are achieved, for example strong chemical resistance, abrasion resistance, and good wettability with organic solvents. Also the pore and void size, which normally lies between 35 % and 50 % changes. Hence the observed new molecule orientation can influence significantly the performance of the Li-ion battery.

Operando Lithium Dynamics in the Li-Rich Layered Oxide Cathode Material Via Neutron Diffraction

The progressive advancements in communication and transportation has changed human daily life to a great extent. While important advancements in battery technology has come since its first demonstration, the high energy demands needed to electrify the automotive industry have not yet been met with the current technology. One possible cathode material are the Li-rich layered oxide compounds xLi2MnO3.(1-x)LiMO2 (M= Ni, Mn, Co) (0.5=<x=<1.0) that exhibit capacities over 280 mAh g-1. In this class of compounds, lithium ions reside in both lithium layer and transition metal layer of close packed oxygen framework, typical from O3 type layered oxides like LiCoO2.1 , 2 Large irreversible capacities are often observed in these materials due to irreversible oxygen loss or side reactions stemming for the electrolyte. It has been also observed using ex-situ NMR that lithium reinsertion back into the transition metal layer is little to none. However, these studies have not revealed the dynamic process of lithium migration for the Li-rich material under operandoelectrochemical cycling conditions. Neutron scattering has several distinct advantages for battery studies: 1) The sensitivity of neutron to light elements such as lithium and oxygen are significant in order to determine their position in the crystal structure; 2) Compares to the X-ray, the neutron shows larger scattering contrast between neighboring elements in the periodic table specifically the scattering lengths; and 3) The deep penetration capability of neutron allows simultaneous observation of the cathode and anode.3 However, challenges exist in broadening the application of operando neutron diffraction for Li-ion batteries research. First, limited by the generation reactions of neutrons, the neutron flux is usually several orders of magntitude lower than X-rays. In another words, longer acquisition times as well as larger amounts of samples are required for neutron diffraction experiments. In addition, the existence of hydrogen, which has a large incoherent neutron-scattering cross-section, is detrimental to the signal-to-noise ratio of neutron diffraction pattern. Separators (polyethylene based porous membrane) and poly carbonate based electrolyte solutions contain a considerate amount of hydrogen. These two major reasons pose significant challenges to operando neutron diffraction for lithium ion battery research although it is such a powerful technique for light elements like lithium. In order to gain more in-depth insights about the lithium (de-)intercalation mechanisms in Li-rich layered oxides, track particularly the lithium ions in transition metal layer, operando neutron diffraction experiments were designed to quantitatively observe lithium migration in this type of oxides during the electrochemical process. In this study, we use amorphous silicon as an anode for the neutron diffraction battery design in order to avoid any overlap of signal that may be associated with the anode material. We perform operando neutron diffraction to probe lithium and oxygen for a high Li-rich (HLR), Li[Lix/3Ni(3/8-3x/8)Co(1/4-x/4)Mn(3/8+7x/24)O2 (x = 0.6) material, and low Li-rich (LLR), Li[Lix/3Ni(1/3-x/3)Co(1/3-x/3)Mn(1/3+x/3)O2 (x = 0.24) material with varying degrees of the high voltage plateau. In conjunction with the operando neutron diffraction, density functional theory (DFT) calculations were used to explore the incorporation of dilute oxygen vacancy, its affect on the lattice mechanics and oxygen positions. We also observe site-dependent lithium migration taking place during different stage of charging/discharge processes. Furthermore, this work demonstrates the potential of investigating dynamic changes of light elements in large format (10-100 times larger format than the typical operando cells for synchrotron X-ray diffraction) prismatic and cylindrical batteries under realistic cycling condition via operando neutron diffraction method. Acknowledgements UCSD’s efforts are supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy (DOE) under Contract No. DE-AC02-05CH11231, Subcontract No. 7073923, under the Advanced Battery Materials Research (BMR) Program. The neutron experiments benefited from the SNS user facility, sponsored by the office of Basic Energy Sciences (BES), the Office of Science of the DOE. H.L. acknowledges the financial support from the China Scholarship Council under Award No. 2011631005. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575. Reference 1. H. Liu, D. Qian, M. G. Verde, M. Zhang, L. Baggetto, K. An, Y. Chen, K. J. Carroll, D. Lau, M. Chi, G. M. Veith and Y. S. Meng, Acs Appl Mater Inter, 2015, 7, 19189-19200. 2. M. G. Verde, H. D. Liu, K. J. Carroll, L. Baggetto, G. M. Veith and Y. S. Meng, Acs Appl Mater Inter, 2014, 6, 18868-18877. 3. H. D. Liu, C. R. Fell, K. An, L. Cai and Y. S. Meng, J Power Sources, 2013, 240, 772-778. Figure 1

New Fluorine-Free Polycyano Fully-Conjugated Aliphatic Anions for Applications in Battery Electrolytes

Lithium-ion batteries are nowadays the most popular energy storage technology. A raising number of research investigates the development of modern batteries, while the market of secondary lithium batteries is still growing. This creates problems with disposal of expired batteries, as many electrolyte components comprise fluorine. Most of lithium-ion batteries research focuses on development of electrode materials. However, apart from electrodes, a key component of Li-ion batteries is electrolyte. Electrolyte limits critical battery properties, such as safety, thermal stability, battery lifetime and internal resistance of a cell. Conventional electrolytes consist of lithium salt, solvent (or solvents mixture) and additives. Since both solvents and additives are well developed and not problematic, in this work we have focused on lithium salts. Among all lithium salts that can be used in large scale manufacturing, LiPF6 is used almost exclusively. Even considering all its advantages, LiPF6has numerous drawbacks, too. These include low thermal stability, moisture sensitivity and toxic and corrosive products evolution upon decomposition [1,2]. In the recent years many studies on new lithium salts have been published, however none of them has been introduced widely to the market so far [3-7]. Therefore, there is a substantial need for new ideas in this field. Our approach was to design new anions for lithium salts tailored particularly for Li-ion battery electrolyte. The concept that we have chosen were anions based on aliphatic chain with conjugated double bonds, that allows π-electrons as well as negative charge delocalization. The chain was fully substituted with nitrile electron withdrawing groups. Application of this ideas should lead to a highly stable and weakly-coordinating anion. As a result we have synthesized two novel lithium salts: lithium pentacyanopropenide (LiPCP) and lithium hexacyano-3-azapentadienide (LiHCAP). Both salts show excellent thermal stability (up to 280 and 350 °C respectively) as proven with means of TGA and DSC. Electrochemical stability tests have shown 4.5 V window width for all salts. Conductivity of the electrolytes containing those new salts have been examined in propylene carbonate and typical battery mixtures. In both cases outstanding conductivity values has been reached, with 10 mS cm-1 have been observed at the room temperature. Lithium cation transference numbers have been investigated as well, giving satisfactory results. Finally, to evaluate compatibility with electrode materials, cycling experiments have been performed both with commercial and custom made electrodes. In conclusion, we have synthesized and thoroughly tested two members of a new class of lithium salts for applications in non-aqueous electrolytes for modern batteries. Obtained results exhibited clearly that LiPCP and LiHCAP would be successfully applied in lithium-ion batteries improving their performance, safety and environmental friendliness.

In-situ TEM on the coalescence of birnessite manganese dioxides nanosheets during lithiation process

Nanostructure is believed to produce great benefits for anode materials in lithium ion batteries (LIBs) by enhancing lithium ion transfer, accommodating large volume change and increasing surface area. Whether the nanostructure (especially the porous nanostructure) could be well held during charging/discharging process is one of the most commonly concerned issues in LIBs research. The dynamic evolution of birnessite manganese dioxides nanosheets during lithiation process is investigated by in-situ transmission electron microscopy (TEM) for the first time. The TiO2@MnO2 core-shell nanowires are used as the anode and Li metal as the counter electrode inside the TEM. Interestingly, the lithiation process is confirmed as MnO2 and Li converting to Li2O and Mn. The original porous structure of the nanosheets is hard to preserve during lithiation process due to lithiation-induced contact flattening.

The Lithium Battery: assessing the neurocognitive profile of lithium in bipolar disorder.

The aim of the present study was to characterize the neurocognitive effects of lithium in bipolar disorder to inform clinical and research approaches for further investigation. Key words pertaining to neurocognition in bipolar disorder and lithium treatment were used to search recognized databases to identify relevant literature. The authors also retrieved gray literature (e.g., book chapters) known to them and examined pertinent articles from bibliographies. A limited number of studies have examined the effects of lithium on neurocognition in bipolar disorder and, although in some domains a consistent picture emerges, in many domains the findings are mixed. Lithium administration appears to reshape key components of neurocognition - in particular, psychomotor speed, verbal memory, and verbal fluency. Notably, it has a sophisticated neurocognitive profile, such that while lithium impairs neurocognition across some domains, it seemingly preserves others - possibly those vulnerable to the effects of bipolar disorder. Furthermore, its effects are likely to be direct and indirect (via mood, for example) and cumulative with duration of treatment. Disentangling the components of neurocognition modulated by lithium in the context of a fluctuating and complex illness such as bipolar disorder is a significant challenge but one that therefore demands a stratified and systematic approach, such as that provided by the Lithium Battery. In order to delineate the effects of lithium therapy on neurocognition in bipolar disorder within both research and clinical practice, a greater understanding and measurement of the relatively stable neurocognitive components is needed to examine those that indeed change with lithium treatment. In order to achieve this, we propose a Lithium Battery-Clinical and a Lithium Battery-Research that can be applied to these respective settings.

Carbon as Quasi-Reference Electrode in Unconventional Lithium-Salt Containing Electrolytes for Hybrid Battery/Supercapacitor Devices

Metallic lithium is the most widespread reference electrode in lithium ion battery research, but its high reactivity limits the usage primarily to conventional carbonate based electrolytes. Novel high power concepts, like hybrid supercapacitors, require lithium containing electrolytes with high ionic conductivity (e.g., acetonitrile), which are not always stable versus lithium. In the current work we face this issue by refining activated carbon as a quasi-reference electrode originally employed for conventional supercapacitors. Different commercially available carbon powders were examined as reference electrode materials and calibrated in lithium-salt containing acetonitrile versus Li+ intercalation/de-intercalation reaction of nanoparticulate Li4Ti5O12. The stability of the activated carbon reference electrode is highly affected by the salt employed and decreases in the following order: LiTFSI > LiClO4 > LiPF6 > LiBF4. Only a negligible impact of electrolyte solvent, pore size distribution and reference electrode binder was observed. Furthermore, activated carbon was functionalized (HNO3 treated) and de-functionalized (thermal annealing in vacuum or hydrogen) to investigate the impact of carbon functionalization on the reference electrode stability. Nitrogen and oxygen containing surface groups have been found to drastically improve long-term stability of activated carbon quasi-reference electrodes. Even after 15 days exposed to the electrolyte, the potential of HNO3 treated activated carbon is marginally altered by 10 mV.

Optimization of Process Parameters during Solid State Synthesis of LiMn2O4 as Cathode Material for Lithium-Ion Batteries

One focus of the present research of Lithium-Ion Batteries is the development of higher energy and higher power density materials. Spinels like LiMn2O4 exhibit a potential of 4.1 V v.s. Li/Li+ that can be further increased by substitution of Mn by transition metals like Ni. Those substituted spinels like LiMn1.5Ni0.5O4 are highly interesting cathode-materials for the high-energy range up to 5 V. The synthesis of spinels via a solid state route enables the production of high amounts up to 100 g with inexpensive starting materials and a combined step for milling and homogeni­zation of the raw materials. However, the solid state synthesis is a challenging approach regarding an adequate homogenization and a potential eva­po­ra­tion of Li during calcination[1]. The present work aims the characterization of calcined cathode-materials to control the processing parameters in order to prepare single-phase spinel materials. Therefore, different compositions of LixMn2O4 have been synthesized from Li2CO3 and MnO2 as starting materials, applying different milling parameters and calcination conditions. The calcined powders were then characterized by powder diffraction (XRD) and electron-paramagnetic-resonance spectroscopy (EPR). It is known that Li2MnO3 might be formed during the calcination process as an undesirable lithium-rich secondary phase[2]. Thus, particular attention has been paid on this phase. The formation of Li2MnO3 may occur by non-homogeneous mixing or remaining coarse particles of Li2CO3 in the powder mixture. The EPR is a highly sensitive method to obtain even small amounts of Li2MnO3 besides LiMn2O4in the calcined product and is therefore highly interesting for this application. [1] Y. Lee, The Effects of Lithium and Oxygen Contents Inducing Capacity Loss of the LiMn2O4 Obtained at High Synthetic Temperature, Journal of Electroceramics, 9, 209 – 214, 2002. [2] V. Massarotti et al., Stoichiometry of Li2MnO3 and LiMn2O4 Coexisting Phases: XRD and EPR Characterization, Journal of Solid State Chemistry, 128, 80 – 86, 1997.

Effect of Carbonaceous Materials on the Electrochemical Performance of Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;/C as an Anode Material for Lithium-Ion Secondary Batteries

The iron oxide anode materials have attracted widespread attention in lithium-ion battery research field. The Fe2O3/C composite was synthesized via hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD confirmed that the main crystallization phases of materials were Fe2O3. The Fe2O3/AC powders showed very uniform cube between 1 and 2 μm. Fe2O3/CNTs composites acted as a three-dimensional network wiring to connect Fe2O3 spheres. The electrochemical investigation indicated that the electrochemical performance of Fe2O3/CNTs materials shows a high specific capacity and an excellent cycling stability. The first reversible capacity of samples is 808.8 mAhg-1 at the current density of 100 mAg-1 between 0.01 and 2.5 V vs. Li/Li+.

New Insights into Structure-Property-Relationship of High-Voltage Electrolyte Components for Lithium-Ion Batteries Using a pka Value Approach

In pursuit of higher energy density in lithium-ion batteries, the general approach is focused on cathode materials that operate at high voltages and exhibit even higher specific charges. To enable the high-voltage application of the cathode, the electrolyte interface needs to be either thermodynamically or kinetically stable. For this reason, the stability of the electrolyte components towards oxidation, in particular, depending on their HOMO energy levels, is crucial. The theoretical calculation of the molecular orbital energies is a helpful and commonly used tool to predict the electrochemical stability[1]. Earlier studies demonstrated strong correlation between the HOMO energy and the pKa value, as both are depending on the electron affinity[2]. Having this in mind, here we report on the first study referring to a pKa value based selection procedure on development of new electrolyte components for the application in lithium-ion batteries. The identified trimethylsilyl(TMS)-based additives, which are known to scavenge HF and show sufficient oxidative stability, enable the application of LiNi1/3Co1/3Mn1/3O2 (NCM) at an increased upper cut-off potential of 4.6 V vs. Li/Li+ without severe degradation, leading to a 50% higher energy density[3]. The selected electrolyte additives were calculated by Hartee-Fock based molecular orbital energy calculations in respect to relevant electronic parameters, and were characterized by linear sweep voltammetry experiments on LiMn2O4(LMO) and constant current cycling experiments in NCM as well as in graphite half-cells. Furthermore, the reaction mechanism was investigated by impedance, SEM, XPS, NMR, GC-MS and ICP-OES techniques. The results reveal that the pre-selection of electrolyte additives by pKa value is a promising approach to identify suitable electrolyte components with high electrochemical oxidation stability. Several TMS-based electrolyte additives, which can considerably improve the capacity retention of NCM cathodes during cycling at high-voltage conditions from 53% (after 50 cycles, 1 M LiPF6 in EC/DMC electrolyte) up to 99% in the same electrolyte containing 1wt-% of TMS based additive, were identified. Due to a higher stability towards oxidation, better leaving group ability and the formation of a more effective cathode passivation layer (CEI), the capacity retention increases with lower pKa value of the leaving group of the TMS based additives. The aforementioned findings provide new insights into the structure-property relationship of certain electrolyte additives, supporting the improvement of the prospective selection procedure of new electrolyte components in lithium-ion battery research.

Polymers: Opening Doors to Future Batteries

Research and development of post lithium ion batteries is attracting considerable attention. While there have been significant advances in understanding the challenges of Li-O2(air) and Li-S batteries, the development of gas separation and ion selective membranes will be crucial in their commercialization due to their potential to separate O2 from air and impede lithium polysulfide dissolution while permitting rapid diffusion of lithium ions. In addition, research leading to novel and highly conductive and selective polymer electrolytes will be essential in overcoming the deficiencies of liquid based electrolytes in both the air and sulfur based battery systems.