bluuebunny/crossref_metadata_2025 huggingface dataset:
High Resolution, in Situ X-Ray Miscroscopy of Batteries
Authors: Weker Johanna Nelson , Wise Anna M , Toney Michael
Published: February 2020

A fundamental component in the global move towards clean, renewable energy is the electrification of the automobile. Current battery technology limits electric vehicles to a short travel range, slow recharge, and costly price tag. Li-ion batteries promise the high specific capacity required to replace the internal combustion engine with a number of possible earth abundant electrode materials; however, setbacks such as capacity fading hinder the full capability of these rechargeable batteries. In the search for better electrode materials, high resolution chemical imaging during typical battery operation is vital in understand and overcoming the failure mechanisms of these materials.

By combining X-ray absorption spectroscopy with high resolution, hard X-ray transmission microscopy (TXM), we have tracked the chemical changes of electrode material in real time during typical battery operation.[1] We will discuss recent results tracking electrochemical and morphological changes in cathode materials during cycling. We will show dramatic chemical and morphological changes during a deep discharges (< 1V) of LiCoO2 and compare these to the changes seen during standard cycling and cycling above the 4.2 V limit consider “safe” for these materials. We have also tracked the Li-ion transport in LiFePO4 agglomerated during electrochemical cycling.[2] We observe spatially inhomogenous charging and discharging that do not correlated with agglomerate size. Finally, we will discuss how ptychography, an emerging X-ray microscopy technique that promises sub-5 nm resolution, has the potential to image batteries during cycling at resolutions that rival in situ TEM with liquid cells.

1.         Nelson Weker, J. and M.F. Toney, Emerging In Situ and Operando Nanoscale X-Ray Imaging Techniques for Energy Storage Materials. Advanced Functional Materials, 2015. 25(11): p. 1622-1637.

2.         Nelson Weker, J., et al., Tracking Non-Uniform Mesoscale Transport in LiFePO4 Agglomerates During Electrochemical Cycling. ChemElectroChem, 2015.
Cu-Based Ternary Fluorides As High-Energy Cathodes for Rechargeable Lithium Batteries
Authors: Wang Feng , Kim Sung-Wook , Graetz Jason
Published: February 2020

Transition metal fluorides are promising for use as high-capacity cathodes in rechargeable lithium batteries for large-scale applications, such as electric vehicles and grid-scale storage, but energy-efficiency and kinetics related issues remain a major hurdle to their commercial use. Cu based fluorides are particularly attractive due to the intrinsic high redox potential and extraordinarily high specific energy density. Here we report on the synthesis, structural and electrochemical properties of new nanostructured ternary metal fluorides, which may overcome some of these issues. By substituting Cu into the Fe lattice, forming the solid solution CuyFe1-yF2, reversible Cu and Fe redox reactions were achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new pathway for tailoring electrochemical properties of conversion electrodes [1]. The Li storage/release mechanisms and limits to cycling stability of CuyFe1-yF2 were also investigated by combining electrochemical measurement with comprehensive structural and chemical analysis using in-situ X-ray absorption spectroscopy, X-ray diffraction, and transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS). Detailed lithium reaction mechanisms, Cu-loss related issues along with possible remedy solutions in the CuyFe1-yF2 system, will be discussed.   The work was supported as part of the NorthEastern Center for Chemical Energy Storage, an EFRC Center funded by the U.S. DOE-BES, under Award Number DESC0001294, and by DOE-EERE under the Advanced Battery Materials Research program, under Contract No. DE-SC0012704.   [1] Wang et al., “Ternary Metal Fluorides as High-Energy Cathodes with Low Cycling Hysteresis”, Nat. Commun. 6: 6668 (2015).

Figure 1
Bulk and Interfacial Kinetics of Li1-XNi0.8Co0.15Al0.05O2 (NCA) Single Particles As a Function of State of Charge
Authors: Tsai Ping-chun , Wen Bohua , Yu Hui-Chia , Choe Min-Ju , Thornton Katsuyo , Chiang Yet-Ming
Published: February 2020

At the length scale of electrode particles, interfacial reaction and/or bulk diffusion may determine rate-performance of lithium ion batteries (LIBs). In a conventional cell, in which electrodes are composed of active materials, binders, conductive agents, and current collectors, the mixtures of different materials result in a complex architecture, posing a great challenge to extract the intrinsic kinetic parameters of the electrode materials. In this work, we conduct single-particle experiments to directly measure the particle-level kinetics, and elucidate the rate-performance determining factors in LIBs. The scheme of our single-particle measurements is shown in Figure 1 [1]

Li1-xNi0.8Co0.15Al0.05O2 (NCA) is chosen as the model electrode material because of its extensive commercial utilization in LIB cathodes [2]. Here, for the first time, NCA single-particle kinetic parameters, including bulk diffusivity and exchange current density, at different states of charge (SOC) and particle sizes are systematically investigated using electrochemical impedance spectroscopy (EIS) and potentiostatic intermittent titration technique (PITT). Based on these obtained particle-level kinetic parameters, we will directly evaluate the relative kinetic contributions to overpotential at the particle level as a function of SOC and particle size, using Biot number analysis [3,4]. In coordination with the experiments, single-particle electrochemical simulations that take particle geometry, interface transport, and surface reactions into account are performed with EIS and PITT conditions. The synergic integration of experiments and simulations will examine and interpret the bulk and interfacial kinetics of NCA single particles. The dependence of these particle-level characteristics on other variables such as cathode composition, primary crystallite size, temperature, cycling history, and electrolyte composition will be discussed.

Acknowledgments

This work was supported as part of the North East Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012583. P-cT thanks the Ministry of Science and Technology, Taiwan (MOST 104-2917-I-006-006), for financial support.

References

[1] I. Uchida et al., J. Power Sources, 68, 139 (1997).

[2] R. Amin et al., J. Electrochem. Soc., 162, A1163 (2015).

[3] Juchuan, Li et al., J. Phys. Chem. C, 116, 1472 (2012).

[4] C. Montella et al., J. Electroanal. Chem., 518, 61 (2002).

Figure 1
Assessment of High-Energy and High-Power Graphite Anodes with Transmission Line Models
Authors: Weiss Michael , Ender Moses , Ivers-Tiffée Ellen
Published: February 2020

Both, chemical composition and microstructure characteristics control the performance of electrodes for batteries. High-power and high-energy lithium ion batteries are composed of electrodes with similar or different chemical composition, but are always distinguishable by their electrode microstructure characteristics. But two-dimensional analysis methods like electron microscopy fail to quantify the key properties of different electrode microstructures.

X-ray tomography is best-suited [1] for three-dimensional anode reconstructions. This study investigates anodes removed from two consumer cells (1 Ah), namely a high-energy cell and a high-power cell.

Based on X-ray micro-CT reconstructions of the graphite anodes comprehensive sets of structural parameters are obtained. An in-depth analysis of (a) volume fractions, (b) surface areas, (c) particle size distributions and (d) tortuosity, gives insight into the different designs of the electrodes. Electrochemical impedance spectroscopy [2, 3] was performed and analyzed by the distribution of relaxation times (DRT) [4], enabling a separation of the several loss processes by their individual time constants. A transmission line model (TLM) [5] was set up assessing quantitatively the contribution of electronic and ionic transport in the porous electrode structure, as well as charge transfer and SEI resistance.  Given the fact, that the effective ionic conductivity is 8 times smaller in the graphite anode of a high-energy cell, the contribution of lithium-ion transport through the electrolyte filled pores becomes significant for high currents. 

References:

[1] M. Ender, J. Joos, A. Weber, E. Ivers-Tiffée, J. Power Sources 269 (2014) 912-919

[2] J. Illig, M. Ender, T. Chrobak, J.P. Schmidt, D. Klotz, E. Ivers-Tiffée, J. Electrochem. Soc. 159 (2012) A952-A960

[3] J. Illig, M. Ender, A. Weber, E. Ivers-Tiffée, J. Power Sources 282 (2015) 335-347

[4] H. Schichlein, A.C. Müller, M. Voigts, A. Krügel, E. Ivers-Tiffée, J. Appl. Electrochem. 32 (2002) 875-882

[5] J. Euler, W. Nonnenmacher, Electrochimica Acta 2 (1960) 268–286

Figure 1
Novel Additives for Improving Safety and Cyclability of Li-Ion Batteries
Authors: LO Jen Chih , Leu Chyi Ming , Yang Chang Rung , PAN Jing Pin , Lee Tzong Ming , SU Chun Wei
Published: February 2020

Introduction

In recently, applicability of secondary batteries such as Li-ion batteries has been realized as power sources for portable electronic devices, electric vehicles (xEVs) and stationary power systems. Consequently, a strong need for the highly electrical performances of batteries due to increase in the capacity constituting a battery pack has grown. Among cell properties, cyclability and safety are the most critical issues for application. According to previous studies, cyclability could be affected by metal dissolution from cathode active material, lithium plating at low temperature or overcharge conditions, and properties of solid electrode interphase (SEI). Safety issues mainly results from internal or external short-circuit of batteries, caused by direct contact of cathode/anode, lithium dendrite penetration to separator, separator shrinks or meltdown, and so on.

At present investigation, we develop a composite additive (called TOC) comprising flouropolymer and clay particles. The TOC will form a continuous phase and simultaneously modify the anode surface. The effects of novel additives have been examined by SEM, electrochemical and safety analysis. Beyond the electrolyte additive and cell design, this research proposes another facile strategy via surface modification that provides excellent protection to improve the cyclability and safety in the meantime.

Results and Discussion

The surface morphology of active materials of MGP-A electrode that has been modified by TOC was analyzed by SEM. Generally, batteries which covered by polymeric layer display merely adequate performance of electricity. Such phenomenon results from hindering the lithium ion transportation between electrode and electrolyte while charging and discharging. Nevertheless, the results of cyclelife test at high temperature in Fig. 1, shows that battery with TOC additive possesses superior capacity retention after 300 cycles. The improvement of electrochemical properties could be attributed to not only the higher uptake of liquid electrolytes by the nanocomposites, but also facile the lithium transport by reducing interfacial resistance during charge and discharge.

Internal short-circuit (ISCr) plays a critical role in failure of batteries. Therefore, we simulate and examine the cell under ISCr condition through penetration test (Fig.2). The maximum temperature of TOC cell was merely 80°C, which is much lower than the pristine one (742°C). We suggest that the continuous film which formed by TOC additive have ability to protect the cell from directly contact of electrode while separator meltdown. Consequently, it prevents further ISCr and keeps battery safe.

Figure 1
Float Charging and Its Effects on Lithium-Ion Cells - What Can We Learn?
Authors: Swart Jan , Spray Ryan
Published: February 2020

Typically aqueous based battery technology allows for float charging.  Float charging is a charge condition where the battery is continuously charged at a low current level sufficient to not cause damage to the battery.  Float charging is often used to balance the cells in a series string or “stack.”  The premise is that lithium-ion batteries are a paradigm shift from aqueous based batteries due to their unique operating mechanism.  The question “why is float charging not always desirable?” came about and testing and analysis was performed on batteries subjected to float charging over a three month period.  The cells were evaluated at an electrode level using cell cross sectioning as well as optical and electron microscopy techniques. This presentation describes charge algorithms and also the observations obtained from the tests that were performed.
Characterization of Safety Aspects of Li-Ion Batteries for Maritime Applications
Authors: Forseth Sissel , Lian Torleif , Gilljam Martin , Weydahl Helge
Published: February 2020

Electrical cars and consumer electronics use since several years back Li-ion batteries as electrical energy storage. This means that the Li-ion battery technology is mature enough for these applications. However, in maritime applications there are some issues to be solved, especially related to safety. The battery will be in a confined space and in many cases be much larger.

In addition to having high energy density, Li-ion batteries contain combustible material and most of the chemistries do also release oxygen[1] [2] [3]. Flammable gases such as hydrogen, carbon monoxide, methane, ethane etc. are also released up on heating[4]. Heating of the battery can be caused by internal flaws, e.g. particles from the cell production[5] and poor battery management design as well as external incidents such as fire.

In order to ensure a safe electrical/hybrid electrical power vessel, all data from electrical and safety tests (on cell and battery level) should be considered as a database of information. This information is vital to ensure a proper design of the battery and the battery room for the vessel in question. Included in the battery room design are the physical dimensions of the room and systems for mitigating the consequences of a battery vent, battery fire and possible gas explosion.

There are many factors that affect the safety of lithium-ion cells, such as chemistry, size, geometry and cell environments. Aging and cycling could also affect the safety properties. We have studied the thermal response of batteries during controlled heating (calorimetric techniques). Amongst the techniques used in our study is controlled heating by the use of an Accelerating Rate Calorimeter (ARC). In this case the size, geometry and cell environment have been kept constant, while different battery chemistries are varied.

The results obtained from the ARC tests on new 18650 cells show that the highest heat rate does not necessarily correspond to the most severe physical result. The results from aged and cycled cells will also be discussed.

[1] MacNeil, D.D. and J.R. Dahn, The Reaction of Charged Cathodes with Nonaqueous Solvents and Electrolytes: I. Li 0.5CoO2. Journal of The Electrochemical Society, 2001. 148(11): p. A1205.

[2] Arai, H., et al., Thermal Reactions Between Delithiated Lithium Nickelate and Electrolyte Solutions.  Journal of The Electrochemical Society, 2002. 149(4): p. A401.

[3] Doughty, D.H., A general discussion of lithium ion battery safety, in The Electrochemical Society Interface. 2012. p. 37-44.

[4] Rothe, E.P. 19, s-l.: ESC Translations, 2008, Vol.11, pp.19-41. 10.1149/1.2897969

[5] Aircraft Incident Report, Auxiliary Power Unit Battery Fire Japan Airlines Boeing 787-8, JA829J, Boston, Massachusetts January , 2013, National Transportation Safety Board.
Performance of Lithium-Ion Battery When Operating in Radioactive and High Temperature Environment
Authors: Tan Chuting , Lyons Daniel Joseph , Zheng Yuan Fang , Co Anne C. , Cao Lei Raymond
Published: February 2020

Lithium Ion Batteries (LIBs) are widely used in research, industry and households, especially equipped in autonomous systems, such as mobile robots in air, land, or sea.  More importantly, some of the environments are filled with nuclear radiation and with high temperature. The performance of LIBs in these environments are crucial to sustained operations of these systems. Unfortunately, how an LIB may degrade the operation of such systems has not been seriously studied in the field. Researches on LIBs material, performance, sustainability, etc. have been done through recent decades. Many kinds of cathode, electrolyte and anode material have been discovered and several configurations, like coin cells, cylinder cells, and prismatic cells have been developed for different operating conditions. The concern is still on the performance degradation and reliability when operating in radiation and high temperature environments such as in outer space exploration, to power robots in hot cell, and equipment for performing rescue or sampling missions at post-nuclear accidents. In this study, we designed an in situ methodology to monitor LIBs performance degradation when operating (cycling) under gamma radiation with a post-accident dose rate (~30krad/h), in terms of capacity fade and impedance rise. Coin cells were assembled using commercial cathode material and electrolyte, with Li as reference electrode. An ex-situ irradiation -testing protocol was also adopted in this study, as we were interested in investigating separate radiation effects on individual battery components. Additionally, the effect of radiation on battery materials may be different at various temperature environment, for example, in space or in a nuclear accident field.  We have conducted battery performance under irradiation while heating (80 °C) or cooling (-40 °C). Ex situ studies, including cathode material X-ray diffraction (XRD), and characterizations with Fourier Transform Infrared (FTIR) spectroscopy, ultraviolet–visible spectroscopy (UV-vis) spectroscopy and electron paramagnetic resonance (EPR) will also be discussed.
In-Situ TEM Investigation on Thermal Stability and Oxygen Release Behavior of Charged and Discharged LiCoO2
Authors: Sharifi-Asl Soroosh , Yuan Yifei , Asayesh-Ardakani Hasti , Nie Anmin , Shahbazian-Yassar Reza
Published: February 2020

Since the first discovery of Li ion batteries (LIBs), enormous research has been dedicated to improve their electrochemical performance such as energy density, power density and lifetime. Yet not much research has been focused on the safety issues and thermal stability of these systems.

LiCoO2is one of the most widely used cathode materials in LIBs. High energy density and light weight cell has made it a good candidate for first generation electric vehicles (Tesla roadster) and even airplanes (Boeing 787 Dreamliner). However, due to the poor thermal stability, its application has been limited to the consumer electronics now. It is well known that Charged LCO when exposed to higher temperatures, as in a case of a mechanical impact or overcharge, releases a portion of its oxygen. Released oxygen can react with electrolyte exothermically and trigger a hazardous thermal runaway. In order to hinder this process we need to gain more in-depth knowledge about underlying mechanisms of this harmful reaction and phase/structural transitions.

In-Situ TEM is known to be a powerful method for studying materials in dynamic conditions such as high temperatures. In this study we utilized transmission electron microscopy to study Li1-xCoO2 (0.5<x<1) in different temperatures. High resolution imaging integrated with electron energy loss spectroscopy (EELS) reveals that cobalt valance changes from 4+ to 3+ at less than 300°C and from 3+ to 2+ at about 450°C showing a two-step oxygen release mechanism in charged LCO Simultaneously, selected area diffraction pattern (SADP) suggests formation of Li vacancy super-lattice and defects such as twins at about 300°C. Going further in temperature results in increase in density of defects and formation of grain boundaries. These findings can be helpful in improving the structural stability of these materials.
Evaluation of Additive Performance on Charged Ncm Surface through Potentiostatic Holds
Authors: Tornheim Adam , Sahore Ritu , Bareno Javier , Bloom Ira , Zhang Zhengcheng
Published: February 2020

In an effort to achieve higher energy density batteries, many higher voltage cathodes are being investigated.  However, at high voltage (V>4.5 vs. Li/Li+), conventional carbonate electrolytes are unstable, leading to electrolyte oxidation and subsequent drop in battery performance.  Two possible methods for mitigating electrolyte oxidation are through the use of intrinsically stable electrolytes at the elevated cathode voltage, or through the use of electrolyte additives that sacrificially decompose on the charged cathode surface, impeding further oxidation of the electrolyte.  Evaluation of electrolyte or additive performance is traditionally accomplished by cycling tests or through voltammetry with platinum or carbon working electrodes, however each of these methods has intrinsic gaps.  Capacity retention can be affected by electrode ‘slippage’ as well as electrode-electrode effects, and voltammetry on inert working electrodes is not evaluating reaction rates on a representative surface.  Determining oxidation rates at the cathode surface is of great value in the design of passivating additives.

In this work, stability of electrolytes was assessed using high voltage potentiostatic holds (4.6V vs. Li/Li+, for at least 60 hours) at elevated temperature with a NCM (LiNi0.5Co0.2Mn0.3O2
) electrode as the working electrode and an LTO (Li4Ti5O12) electrode as a counter and reference.  A 60 hour potentiostatic hold allows for the relaxation of electrode polarization such that the dominant contributor to external current is oxidation reactions, allowing a quantitative measure of electrolyte decomposition rate.  Within this protocol, the passivating effect of various additives can be evaluated both during and after the potentiostatic hold by comparing oxidation current for an additive-containing electrolyte to the baseline.  Upon completion of the potentiostatic hold, the capacity and impedance are measured, and cells were disassembled with components characterized by XPS, LC-MS, and IR. 

Acknowledgements

The work at Argonne National Laboratory was performed under the auspices of the U.S. Department of Energy (DOE), Office of Vehicle Technologies, under Contract No.

DE-AC02-06CH11357. 

The submitted issue has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-Eng-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, non-exclusive, irrevocable, worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
Optimising the Concentration of LiNO3 in C4mpyr-Tfsi-Based Electrolyte in Li-S Batteries
Authors: Musameh Mustafa , Barghamadi Marzi , Best Adam Samuel , Hollenkamp Anthony F. , Mahon Peter , Ruether Thomas
Published: February 2020

In the lithium-sulfur (Li-S) context, LiNO3 is known to improve the battery performance by forming efficient SEI layer on the lithium anode and consequently prevent or minimise chemical and electrochemical reduction of polysulfides on the anode and suppress the associated lithium polysulfides shuttle effect during cycling. Mikhaylik, from Sion Power Corp. [1], has patented, for the first time, a method that employs N-O bond containing additives, such as LiNO3, in the electrolyte to suppress the PS shuttle effect. Herein, the modification of LiNO3 additive concentration (0.05 to 0.4 mol kg-1) in a C4mpyr-TFSI electrolyte-based Li-S system, for the first time with the best of our knowledge, is investigated in which 0.1 mol kg-1 was determined to be the optimum concentration in the blended IL-organic electrolyte as a result of higher conductivity and higher ion mobility.

Similar performance of cells with different nitrate additive concentrations at 50 oC confirms the correlation between ionic conductivity/viscosity and cell performance. Pulsed field gradient-NMR (PFG-NMR) is utilized to measure diffusion coefficients for cations and anion the electrolytes. The data shows higher diffusion coefficients (therefore higher mobility) for anion and cations in electrolyte containing 0.1 mol kg-1 compared to electrolytes with higher or lower LiNO3 additive at room temperature. Furthermore, the lower D values for TFSI- and Li+ compared to pyrrolydinium cation confirms the transportation of Li+ in the form of [Li(TFSI)n](n-1)- complex in the electrolyte.

1.            Mikhaylik, Y.V., Electrolytes for lithium sulfur cells. 2008, SION POWER CORPORATION: US.
Investigation of Anode/Cathode Electrolyte Interfaces at High Cell Voltages with and without Additives
Authors: Liu Dongqing , Luo Dan , Qian Kun , Li Baohua
Published: February 2020

The electrodes electrolyte interfaces of lithium ion battery at high cell voltages were investigated by using in-situ electrochemical impedance spectroscopy (EIS) with three electrodes cell. NCM/C system electrodes were investigated separately in the electrolyte of LiPF6 in ethylene carbonate (EC) and dimethyl carbonate (DMC) with and without the most commonly used additives vinylene carbonate (VC), vinyl ethylene carbonate (VEC) and fluoroethylene carbonate (FEC). Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) were carried out to examine the stability of additives at the electrodes electrolyte interfaces at high cell voltage. This work provides valuable information for lithium ion battery at high cell voltage especially in the choice of electrolyte additives.
Li Salt Rich Separator for Li-Ion Batteries
Authors: Mourzagh Djamel
Published: February 2020

In order to reduce the duration of the electrolyte filling step, a new concept of separator embedding itself Li salt thanks to a Li salt rich film coated on. The objective of study was to quantify the impact (benefits and drawbacks) of a Li salt containing PVdF based film deposited by coating onto a conventional polyolefin based separator. A protocol for elaborating the salt based polymeric solution to be coated onto a commercial polyolefin separator was developed at CEA/LITEN. Separators were coated with solutions at a defined coating thickness. The samples were characterized in terms of salt loading, morphology of the layers, adhesion of the film on the separator, ionic conductivity and ability to be soaked by the electrolyte. Some cycling tests were undertaken in full coin cells Cgr / LiFePO4 and soft pouch cells with samples of coated separators in order to evaluate the impact of the manufacturing conditions on the electrical performances. The impact of the storage conditions of the coated separator was also studied.
Functional Ionic Liquid Based Electrolytes
Authors: Moganty Surya
Published: February 2020

NOHMs Technologies is developing functional ionic liquid based hybrid electrolytes for high energy density, high voltage, and high power batteries for EV and military applications. The composition of electrolytes greatly affects the cell performance from rate capability, lithium cycling efficiency, and capacity retention at various temperatures to tolerance against electrical, mechanical and thermal abuses. Ionic liquids offer a host of attractive properties, including ultralow vapor pressure, high thermal stability, high ionic conductivity and wide electrochemical stability, which make them attractive as electrolytes. However, there are some physical property limitations that to-date has made them unattractive for lithium battery applications. High viscosity and the fraction of the ionic conductivity of the electrolyte arising from mobile lithium ions (i.e. the so-called lithium transference numbers) are typically low for these materials, which make cells assembled using ionic liquid electrolytes prone to large polarization during operation of the cell. These limitations can be easily overcome by blending ionic liquids with appropriate co-solvents. These hybrid electrolytes simultaneously overcome the poor thermal & electrochemical stability and safety problems that have plagued lithium battery electrolytes for years while still maintaining high conductivity. They provide a platform for engineering electrolytes with both chemical and interfacial tunability that beyond improving safety, expand the range of available battery form factors.

During the presentation, we will show how the ionic liquid functionality affects the SEI formation on the graphite anode and high voltage stability. We intend to answer the following questions: 1) functional ionic liquid and co-solvent formulations to achieve a  >4.5V electrolyte, 2) is the capacity fade dependent on the upper voltage cut-off, and 3) how the electrolyte formulations improve the capacity retention of at high voltages and elevated temperatures using 200 mAh pouch cells.

Figure 1
Investigation of Electrolytes for Sio/Graphite Anode Based High Energy Cells
Authors: Wang Jun , Campion Christopher , Vurgaropulos Adam , Pinnell Leslie , Johnson Derek C
Published: February 2020

High energy cells with SiO/graphite composite anode tend to demonstrate fast capacity fade and gas generation during long term cycling test, due primarily to large volume expansion of Si particles and continuous SEI formation which consumes electrolyte components quickly. As a result, loss of accessible anode material and depletion of electrolyte are common failure mechanisms. Overcoming those challenges requires careful electrolyte formulation to create a stable anode SEI layer with the goal of extending cycle life and reducing cell gas generation.

In this study, a commercial grade small-format pouch cell with SiO/graphite and NCM 523 was selected as an electrochemical test vehicle to screen various electrolyte formulations. A baseline was obtained with commercial electrolytes, which revealed fluoroethylene carbonate (FEC) as a key enabling additive for cycle life. Unfortunately severe cell gassing is often observed with cells that exhibited superior cycle life. A rigorous electrolyte formation matrix was then constructed by varying FEC content, solvent type and ratio, introducing anti-gassing additives and mixed salts. Subsequent testing of these formulations demonstrated that up to 2% 1,3-propane sultone (PS) could effectively reduce cell gassing, but the associated higher cell impedance also adversely impacted cycle life.  Formulations with lithium bis(oxalato)borate (LiBOB) as a secondary salt had little influence on cell cyclability but significantly increased cell gassing.  The culpability of the additive was confirmed via gas composition analysis. Other variables such as solvent ratio and additives commonly used in graphite based cells appeared to be much less effective for Si containing anodes. Through composition modification, an optimal electrolyte formulation was identified with long cycle life and low gas generation.
Enhanced Electrochemical Performance of Li4Ti5O12 Anode for Lithium Ion Batteries with Titanate Coupling Reagent As Electrolyte Additive
Authors: Zhang Yixiao , Han Guangshuai , Lv Taolin , Xie Jingying , Yan Liqin , Cui Xiaoli , Liu Hui , Shao Leijun
Published: February 2020

With the increasing applications of lithium ion batteries in energy storage, electric vehicles and hybrid electric vehicles, it’s required to improve the energy density, safety, rate capability and cycling stability of the batteries. Spinel Li4Ti5O12 is a promising anode material for lithium-ion batteries which possesses good Li+ insertion and de-insertion reversibility with negligible structure change, high safety and rate capability, excellent cycle stability1-2. While the theoretical capacity of it, 175 mAh g-1, is slightly low. Meanwhile, it’s observed gassing during storage or cycling3, limitting its application.It was found that the surface coating could be an effective method to solve the swelling problem and be beneficial to the electrochemical performance4.

In this paper, we investigated the effect of titanate coupling reagent TCA-K38S as electrolyte additive on the performance of Li4Ti5O12. TCA-K38S, isopropyl tri-(dioctylpyrophosphate) titanate, is a liquid monoalkoxy pyrophosphate titanate, usually used as coupling agent not only finorganic fillers with resins, but also fnon-polar materials with polar materials, the structural formula is shown in Fig.1. The electrolyte used in this work are 1.2 mol LiPF6 in EC/ EMC solvents ((3:7 by volume), the TCA-K38S was added at 1wt.% and 3 wt.% to the electrolyte solution. Fig.2 shows the cycling performance of Li4Ti5O12 batteries with different amounts of the TCA-K38S additive at various rates. It can be seen that the specific capacity of batteries with 1wt.% additive is 180 mAh g-1 at the first discharge and stable in 170mAh g-1 at 0.2 C, comparied to 162mAh g-1 and 158mAh g-1 at 0.2 C when it’s without additives.

Acknowledgements

The project was supported by the National High Technology Research and Development Program of China (863) (2013AA050902) and Shanghai Science and Technology Development Fund (15DZ2282000, 14JC1491800) .

References

[1]. Z. Huang, D. Wang, Y. Lin, X.Y. Wu, P. Yan, C.M. Zhang, D.N. He, J. Power Sources, 266 (2014) 60-65.

[2]. E. Pohjalainen , J. Kallioinen , T. Kallio, J. Power Sources, 279 (2015) 481-486.

[3]. K. Wu, J. Yang, Y. Liu, Y. Zhang, C. Y. Wang, J.M. Xu, F. Ning, D.Y. Wang, J. Power Sources, 237 (2013) 285-290.

[4]. Z.J. Ding, L. Zhao, L.M. Suo, Y. Jiao, S. Meng, Y.S. Hu, Z.X. Wang, L.Q. Chen,  Phys. Chem. Chem. Phys., 2011, 13, 15127–15133.

Figure 1
Solid Polymer Electrolytes Based on Functionalized Tannic Acid Derivatives from Natural Resources for All-Solid-State Lithium Batteries
Authors: Shim Jimin , Baik Ji-Hoon , Lee Jong-Chan
Published: February 2020

Solid polymer electrolytes (SPEs) comprising crosslinking agent and plasticizer based on natural resources, tannic acid (TA), were prepared by facile one-pot ultraviolet (UV) light induced polymerization for all-solid-state lithium-ion battery applications. Poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting unit and methacrylated TA (MTA) as a crosslinking agent are copolymerized in the presence of poly(ethylene glycol)-grafted TA (PTA) as a plasticizer. Dimensionally stable free-standing SPEs are obtained with the incorporation of very small amount, 0.1 wt%, of MTA compared to that of the PEGMA due to high crosslinking efficiency of the MTA. When 2.0 wt% of PTA with wax state having ion-conducting chain is added, maximum ionic conductivity of 5.6 x 10-4 S/cm at 30 oC is obtained which is one magnitude larger than that of the waxy P(PEGMA) without any crosslinking agent.

Figure 1
In Situ Gas Analysis of Li-Ion NixCoyMnz Cathode Interface Reactivity
Authors: Berg Erik J. , Bolli Christoph , Guéguen Aurélie , He Minglong , Streich Daniel , Novák Petr
Published: February 2020

Li-ion cathode materials based on xLi2MnO3·(1–x)(NiyCozMn1-y-z)O2 (NCM), including both the stoichiometric (x = 0) as well as the Li-rich derivatives (x > 0), are currently under intensive research and development to be implemented in the next-generation batteries because of their high specific charge and operating potential [1, 2]. By tuning the transition metal composition, the cathode properties can be tailored according to application specific requirements: specific charge, rate capability and cycle life. However, compositions offering higher cell energies (e.g. Li- and Ni-rich) generally display increased reactivity towards the electrolyte that may unfavorably influence the thermal stability, impedance and capacity retention of the cells [3]. We demonstrate in situ gas analysis to be a powerful tool to both characterize and in turn mitigate performance limiting interface side-reactions of NCM cathodes and carbonate based electrolytes.

Online electrochemical mass spectrometry (OEMS) enables the in situ analysis of gases evolving inside the electrochemical cell during cycling [4]. The nature, onset, and extent of evolving volatile species provide crucial mechanistic understanding of transformation/decomposition reactions of both the electrode and electrolyte. Side-reaction products associated with the electrolyte LiPF6 salt (e.g. POF3, …), solvent (H2, C2H4, …), and electrode (O2, CO2,…) are readily discernable with high sensitivity and correlated to the electrochemical response during the charge/discharge process. We demonstrate the initiation of a continuous LiPF6mediated electrolyte decomposition cycle at high cell voltages, which drastically increases acidity of the electrolyte and dissolution of the active materials [5]. The influence of the transition metal composition of the active material [6], electrolyte solvents [7], and additives [8] (EC, FEC, VC, …) with respect to the anodic electrolyte decomposition is demonstrated.

[1] P. Rozier, J.M. Tarascon, Journal of The Electrochemical Society, 162 (2015) A2490-A2499.

[2] E.J. Berg, C. Villevieille, D. Streich, S. Trabesinger, P. Novák, Journal of The Electrochemical Society, 162 (2015) A2468-A2475.

[3] H.-J. Noh, S. Youn, C.S. Yoon, Y.-K. Sun, Journal of Power Sources, 233 (2013) 121-130.

[4] E. Castel, E.J. Berg, M. El Kazzi, P. Novák, C. Villevieille, Chemistry of Materials, 26 (2014) 5051-5057.

[5] A. Guéguen, D. Streich, M. He, M. Mendez, F. Chesneau, P. Novák, E. J. Berg, Submitted.

[6] D. Streich, J-Y. Shin, F. Chesneau, P. Novák, E. J. Berg, Submitted.

[7] D. Streich, A. Guéguen, M. Mendez, F. Chesneau, P. Novák, E. J. Berg, Submitted.

[8] A. Guéguen, C. Bolli, M. Mendez, F. Chesneau, P. Novák, E. J. Berg, Submitted
Improvement of Electrode/ Electrolyte Interfaces in Graphite/LiNi0.5Mn1.5O4 Batteries at High Voltage and Elevated Temperature By Using New Family of Lithium Pyridal Trimethyl Borates
Authors: Dong Yingnan , Lucht Brett L , Xu Mengqing , Zhou Liu , Chen Yanjing , Demeaux Julien , Mac Intosh Alex , Meini Stefano , Garsuch Arnd
Published: February 2020

A novel series or lithium alkyl trimethyl borates and lithium aryl trimethyl borates have been prepared and investigated as cathode film forming additives.  The borates are prepared via the reaction of lithium alkoxides or lithium phenoxides with trimethyl borate.  Incorporation of 0.5-2.0 % (wt) of the lithium borates to a baseline electrolyte (1.0 M LiPF6 in 3:7 (EC/EMC)) results in improved capacity retention and efficiency of high voltage graphite / LiNi0.5Mn1.5O4 cells especially upon cycling at elevated temperature (55 oC).  The improved performance results from the sacrificial oxidation of the lithium borate on the cathode surface to generate a cathode passivation film.  The lithium borates can be readily structurally modified to act as a functional group delivery agent to modify the cathode surface.  Ex-situ surface analysis of the electrodes after cycling confirms that the lithium borates modify the cathode surface and generate a borate rich surface film which inhibits electrolyte oxidation and Mn dissolution.
Solvent, Lithium Salt and Temperature Influence on Stability of Carbonate Based Electrolytes for 5 V LiNi0.5Mn1.5O4
Authors: He Minglong , Boulet-Roblin Lucien , Borel Philippe , Tessier Cécile , Novák Petr , Villevieille Claire , Berg Erik J.
Published: February 2020

Spinel LiNi0.5Mn1.5O4 (LNMO) is one of the most promising next-generation cathode candidates for Li-ion batteries because of its reversible specific charge of 147 mAh/g and a high operating potential of 4.7 V.[1] However, the cycling performance of high-voltage cathodes is limited by the poor anodic stability of the most commonly employed alkyl carbonate electrolytes, e.g. ethylene carbonate (EC) and dimethyl carbonate (DMC).[2] Increasing attention is paid to alkyl carbonate based electrolytes for high-voltage applications, including the selection of co-solvents, additives, the role of lithium salt and possible catalytic effect from the electrode components.

The presented work focuses on the investigation of electrolyte decomposition mechanisms and consequent gas evolutions from LNMO cathode by applying in situ gas analysis techniques, i.e. in situ pressure characterization and online electrochemical mass spectrometry (OEMS).[3] The major detected volatile species include H2, CO, CH3F, CO2, and POF3 (only with LiPF6 salt), which present gas evolution profiles depending on the electrochemical potential and electrolyte composition. Enhanced gas evolution rates are observed by increasing DMC content, exchanging LiPF6 salt to LiClO4 or increasing the cell temperature.[4] Ni cations with different oxidation states on the LNMO surface preliminarily exhibit dissimilar catalytic efficiency towards electrolyte decomposition. Our in situ gas analysis provides valuable insights into electrolyte degradation processes on LNMO cathodes, thus further assisting intensive efforts to enhance both performance and safety of high-voltage Li-ion batteries.

[1] C. M. Julien and A. Mauger, Ionics, 19, 951 (2013).

[2] D. Aurbach, B. Markovsky, Y. Talyossef, G. Salitra, H.-J. Kim and S. Choi, Journal of Power Sources, 162, 780 (2006).

[3] M. He, E. Castel, A. Laumann, G. Nuspl, P. Novák and E. J. Berg, Journal of The Electrochemical Society, 162, A870 (2015).

[4] M. He, L. Boulet-Roblin, P. Borel, C. Tessier, P. Novák, C. Villevieille and E. J. Berg, Journal of The Electrochemical Society, 163, A83 (2016).
Wide Temperature Range Electrolyte Development for Start-Stop Vehicle Application
Authors: Cheng Gang , Zhu Ye , Strand Dee
Published: February 2020

Over the last decade, many governments have implemented more stringent regulations on vehicle fuel economy and CO2 emissions. For example, European targets for new passenger cars reduce emissions to 130g CO2 per kilometer by 2015, with further reduction to 95g by 2021.   Start-stop technology reduces CO2 emissions by shutting off the engine when the vehicle is at a stop, such as traffic lights, and restarts the engine instantly when the driver accelerates the vehicle to proceed. Fuel consumption is also reduced, which is desirable from the vehicle owner’s perspective. Start-stop technology is not new, with initial usage traced back to 1980’s by VW in Fiat. However, this application has been greatly limited by the low energy density and poor cycle life of lead acid batteries, which have been primarily used for this application. Batteries intended for start-stop applications must start the engine a high number of times, must survive limited or extended engine-off periods, and must be able to operate over a wide temperature range (-40° C to 60 °C).

Start-stop automobiles have gained momentum recently because of more stringent carbon emission regulations, but also due to technology enhancements achieved in lithium ion batteries. Compared to lead acid, lithium ion batteries have higher energy density as well as longer cycle life. However, the power performance of lithium ion batteries is limited at the low temperatures required for automotive applications due to low conductivities of the electrolyte and the solid electrolyte interphase (SEI).  Solutions to the low temperature problem generally consist of adding solvents with very low melting points and/or low viscosities to the formulation which keep the electrolyte from freezing or reduce the viscosity at low temperature.  However, these solvents tend to be detrimental to high temperature stability required to meet the lifetime requirements of the vehicle batteries. 

Using its unique High Throughput Battery Workflow, Wildcat has developed promising electrolyte formulations with significantly improved low temperature power performance while improving or maintaining high temperature stability relative to a baseline electrolyte formulation.  Wide temperature range formulations were developed for both NMC//graphite and NMC//LTO electrode chemistries and over 30% improvement on both low temperature power performance as well as high temperature stability has been successfully achieved.

Figure 1. Solvent composition has strong effect on reducing low temperature impedance (blue/purple is best result, gray/red is worst)

Figure 1
Sodium Hybrid Capacitor: A Next Generation Energy Storage System
Authors: Thangavel Ranjith , Kaliyappan Karthikeyan , Baek Seul Gi , Choi Hyun Jun , Ramasamy Hari Vignesh , Lee Gyung Hwan , Sun Xueliang Andy , Lee Yun Sung
Published: February 2020

Sodium ion batteries are emerging candidate for next generation high energy application including electrical vehicles and grid storage.[1] Rather than the similar working principle, the wide availability and low cost of sodium made them a suitable and an interesting candidate for large  energy applications. The research for sodium ion batteries is majorly on improving their poor kinetics due to their large ionic radii resulting in low energy and power density.[2]The possible solution could be designing a hybrid capacitor which greatly improves the energy density and power density simultaneously because of their fast kinetics.

In this work, we have developed and fabricated a new high performing 3 V sodium hybrid capacitor (NHC) using NASICON structured Na3V2(PO4)3 – (NVP) and a carbon derived from bio resource in an organic electrolyte. Two reactions occurs simultaneously, (i) intecalaction / deintercalation of sodium ions in NVP which brings high energy density, (ii) adsorption/ desorption of anion in the bio carbon giving high power density.  An energy density of 118 Wh kg−1 has been achieved at a specific power of 95 W kg−1, retaining 60 Wh kg−1 of energy at high specific power of 850 W kg−1. A superior and an extremly outstanding stability of 95% is achieved after 10,000 cycles. The obtained results are one of the highest ever reported and it outperforms the present lithium hybrid capacitor by all means (energy density, power density, stability).  The results will be presented and discussed in detail.

References:

1)      N. Yabuuchi,M. Kajiyama, J. Iwatate, H. Nishikawa, S. Hitomi, R. Okuyama, R. Usui, Y. Yamada, S. Komaba, Nat.Mater. 2012, 11, 512.

2)      V. Etacheri, R. Marom, R. Elazari, G. Salitra, D. Aurbach, Energy Environ. Sci. 2011, 4, 3243.

Figure 1
Synthesis of Metal Oxide Precursors for the Generation of Oxides or Similar Nanomaterials for Na-Ion Battery Cathode Production
Authors: Fromm Katharina M , Baichette Benoît
Published: February 2020

The current growing need of energy storage is an issue that can be solved at least partially by electrochemical storage, like batteries. Nowadays, most of the Li-ion battery cathodes are made of lithium cobalt oxide, LiCoO2, prepared by highly energy consuming solid state processes, involving solid state method at high temperature and for long reaction times (600-900°C, 36hours [1]). Aurelien Crochet and Jean-Pierre Brog of the Fromm group developed a way of producing the high-temperature phase of LiCoO2 (HT-LiCoO2) [2] at low temperature using heterometallic Li-Co alkoxides complexes as molecular precursors, following the general equation below.

[Li2Co(OR)4(L)4] → HT-LiCoO2 + Li2CO3 + CO2 + H2O

Despite lower performances, Na-ion batteries are good candidates in an effort to produce cheaper and more environmentally friendly batteries compared to Li-ion batteries. Complexes of [NaxMy(OR)z(L)a], where M is a transition metal, OR an alkyl or aryl oxide group and L a ligand, can be synthesized in analogy to the lithium precursors in order to use them for the generation of sodium metal oxides. Those oxides will be characterized and tested as cathode materials. We will present our first efforts and results on this kind of synthesis.