bluuebunny/crossref_metadata_2025 huggingface dataset:
Rigid Pyromellitic Diimide Triangles for Organic Rechargeable Batteries
Authors: Kim Dong Jun , Hermann Keith , Prokofjevs Aleksandrs , Pezzato Cristian , Otley Michael Thomas , Stoddart J.Fraser
Published: February 2020

Employing energy from renewable sources, such as solar and wind, will become increasingly important for sustainable development.1 Organic rechargeable batteries (ORBs) have been receiving a significant amount of attention in the literature for their versatile molecular structure design, sustainability, flexibility and availability from abundant natural sources.2 These attributes will aid in the design of more sustainable technologies.

While recent studies have shown significantly improved electrochemical performances, most of the ORBs are not appropriate for practical applications on account of two reasons. The first is the low cycle life observed for organic electrodes, resulting from dissolution or side reactions with the electrolyte. In order to overcome the dissolution of active materials in the electrolyte, a number of investigations have been directed towards conjugating redox-active molecules with polymers or by incorporating them into gel-polymer electrolytes.3 Secondly, and more importantly, very few electrode candidates show the single well-defined plateau voltage profile which is essential for maximizing the energy density of the full-cell. When we compare conventional transition-metal based electrodes to organic ones, the redox-active organic molecules possess numerous redox states, often having multiple well-defined plateaus. Although several studies have shown that functional group substitution induces overall redox voltage shifts, obtaining a single well-defined plateau using multiple redox-states of organic molecules remains a major challenge.

Herein, we report a new strategic direction. By introducing pyromellitic diimide (PMDI) into a molecular triangle, cyclic through-space electron-sharing occurs. This property results in increased cycle life and, more importantly, a single well-defined output voltage. The PMDI triangle exhibits a single well-defined voltage at 2.2 V, compared to two peaks at 2.2 and 1.7 V, or 2 and 2.7 V, for reduction and oxidation, respectively of PMDI monomeric analogues. Our results suggest that an efficient delocalization of electrons within the triangle is important for obtaining a singly well-defined plateau, and hopefully can be extended to other redox-active organic materials.

1. Armand, M.;  Tarascon, J. M. Building Better Batteries. Nature
2008
451
,652–657.

2. Morita, Y.; Nishida, S.; Murata, T.; Moriguchi, M.; Ueda, A.; Satoh, M.; Takui, T. Organic Tailored Batteries Materials Using Stable Open-Shell Molecules With Degenerate Frontier Orbitals. Nat Mater.
2008, 10, 947–951.

3. Liang, Y.; Tao, Z.; Chen, J. Organic Electrode Materials for Rechargeable Lithium Batteries. Adv. Energy Mater.
2012, 2
, 742–769.

Figure 1
Decoding Lithium-Sulfur Electrochemistry Using Nuclear Magnetic Resonance Spectroscopy
Authors: Mueller Karl T , Han Kee Sung , Hu Jianzhi , Vijayakumar Murugesan
Published: February 2020

Predicting the emergent behavior of the electrolytes and electrodes at their interfaces is crucial for the design of optimal energy storage materials for lithium-sulfur (Li-S) battery applications. For example, understanding lithium polysulfide solvation and diffusion in different solvent mixtures can help us predict the polysulfide dissolution mechanism and subsequently lead to the design of optimal electrolytes. To unravel the emergent behaviors of complex electrolyte systems, we have employed multi-nuclear and pulsed-field gradient (PFG) NMR experiments, obtaining a molecular level understanding of the solution structure and translational dynamics of ions/solvents within Li-S battery electrolytes. Based on this understanding, we proceed to study electrode-electrolyte interfacial process such as the formation of solid-electrolyte interphase (SEI) layers. Metal anodes under various electrochemical conditions were analyzed using multi-nuclear solid-sate NMR spectroscopy to understand ion nucleation (dendrite growth) and reactivity (SEI layer formation) on the electrode surface. Finally, we correlate the NMR-derived local structure to emergent behaviors of electrolyte and electrode-electrolyte interfacial process to gain a comprehensive multiscale understanding of Li-S electrochemistry during charge/discharge processes.
Approaching High-Performance Li-Sulfur Batteries By Surface Modification Using Atomic Layer Deposition
Authors: Meng Xiangbo , Liu Yuzi , Libera Joseph A. , Zavadil Kevin R , Elam Jeffrey W
Published: February 2020

Approaching High-Performance Li-Sulfur Batteries by Surface Modification Using Atomic Layer Deposition

Xiangbo Meng†#, Yuzi Liu‡, Joseph A. Libera†, Kevin R. Zavadil§ and Jeffrey W. Elam†*

† Energy Systems Division, ‡ Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL, USA 60439

§ Materials Science and Engineering, Sandia National Laboratories, Albuquerque, NM, USA 87185

# Presenting author: xmeng@anl.gov; * Corresponding author: jelam@anl.gov

Electrical energy storage (EES) is critical for the widescale implementation of renewable clean energies. With the commercialization of lithium-ion batteries (LIBs) in portable electronics, new battery technologies are being intensively investigated in order to provide higher energy density for other applications such as electrical vehicles. Lithium-sulfur (Li-S) batteries are very intriguing, given their high theoretical specific energy density of 2567 Wh/kg. However, Li-S batteries suffer from a number of major hurdles in practice, such as the insulating S and Li2S, soluble polysufides (Li2Sx, x≥4), and lithium dendrite growth. Although a huge amount of research effort has been invested to date, a lack of viable technologies exists to create high performance for practical applications. In our recent studies, both S cathodes and lithium metal anodes were modified via atomic layer deposition (ALD). Our research disclosed that uniform and conformal ALD coatings are very beneficial for Li-S batteries to approach high performance. Specifically, effects of ALD coating were exhibited in: (1) depressing the shuttle effect of polysulfides and (2) inhibiting lithium dendrite growth. As a result, the ALD-modified Li-S batteries showed improved Coulombic efficiency, much longer cycling lifetime, and enhanced safety. In our studies, different ALD coatings were investigated, including Al2O3 and LixAlyS. This work was supported as part of the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES). Electron microscopy was performed at Center for Nanoscale Materials at Argonne National Laboratory.
Ultrasonic Synthesis and Multi-Scale Model of a Carbon Compartment & Sulfur Composite
Authors: Dysart Arthur D , Burgos Juan Carlos , Mistry Aashutosh , Chen Chien-Fan , Liu Zhixiao , Hong Chulgi , Balbuena Perla B , Mukherjee Partha P. , Pol Vilas G.
Published: February 2020

In the field of battery technology, the lithium-sulfur battery has been widely pursued due to high energy density and high theoretical capacity that can satisfy viability thresholds for electric vehicles. However, this elusive technology remains in the research sector due to a wealth of engineering challenges resulting from the complex chalcogenide electrochemistry. The most infamous challenge remains the polysulfide shuttle effect, in which lithium polysulfide intermediates are produced as elemental sulfur (S8) is reduced to lithium sulfide (Li2S) during the discharge cycle. Since the higher order polysulfides are soluble in organic electrolyte, battery cycling can result in dissolution of the cathode, dendrite formation upon a lithium metal anode, and introduce impedance via electrode passivation. This can ultimately cause rapid capacity fade and unstable Coulombic efficiency.

This work presents a novel carbon-sulfur composite, utilizing a cost-effective, bimodal-porosity carbon substrate and a sonochemical sulfur loading technique to improve mono-dispersity in sulfur distribution. The cavity-rich carbon substrate, appropriately named carbon compartments, is synthesized through a single step heating process of commercial wheat flour. The surface area and bi-modal porosity of the carbon compartments enable high sulfur loading (ca. 70 %-wt.). Optimization of a novel fluorinated-electrolyte demonstrates radical improvement in columbic efficiency and cycling stability of the carbon-sulfur composite. The demonstrated Li-S cathode has shown stable half-cell performance (ca. 750 mAh g-1) and columbic efficiency (> 96 %) for all cycles at a current density of 28 mA g-1.

Further analysis using in-depth multi-scale modeling describes the electrochemical performance of the composite. Density functional theory and ab initio molecular dynamics characterize the development and behavior of sulfur-containing compounds at the electrolyte-composite surface. Stochastic modeling of the composite microstructure describes electrochemical and physical consequences of polysulfide precipitation. This multi-scale model provides fundamental insight into the mechanisms concerning the role of carbon morphology in the polysulfide shuttle phenomenon.
Silver Nanowires for Li-O2 Batteries
Authors: Kwak Won-Jin , Jung Hun-Gi , Aurbach Doron , Sun Yang-Kook
Published: February 2020

In Li-O2 battery system, precipitation of Li2O2 passivate the cathode’s surface during charging, what terminates electrochemical reaction and limit the cell capacity.1,2 In the charging process, oxidation of the non-conductive Li peroxide precipitants requires high over-potentials, in which solution species may be readily oxidized. In order to address these shortcomings, many researchers3,4 tried to modify the morphology, size, and crystallinity of Li2O2 during its generation by electro-catalysis and the use of composite cathodes comprising nano-materials.

Efforts have been made to decrease the overpotential at the formation and decomposition of Li2O2, by identifying catalysts that can control the morphology of Li2O2. Morphological control makes Li2O2 easier to decompose on oxygen evolution reaction (OER). Herein, we show that silver nanowires as cathode materials for Li–oxygen batteries. AgNW greatly reduce the charging over-potential needed for OER at the solution/electrode interface and are more effective than silver nanoparticles (AgNP). AgNW deliver reversible Li2O2 formation/decomposition on discharge/charge with an average charging potential of ∼3.4 V without electrolyte solution decomposition after 50 cycles. We confirmed that unique Li2O2 structure can promote the decomposition at low charge potential upon oxygen evolution reaction leading to high electrical efficiently of Li-air batteries up to 83.4%.

References

 

(1)     Kraytsberg, A.; Ein-Eli, Y. J. Power Sources
2011, 196, 886–893.

(2)      Viswanathan, V.; Thygesen, K. S.; Hummelshoj, J. S.; Norskov, J. K.; Girishkumar, G.; McCloskey, B. D.; Luntz, A. C. J. Chem. Phys.
2011, 135, 214704 (1–10).

(3)      Mitchell, R. R.; Gallant, B. M.; Shao-Horn, Y.; Thompson, C. V. J. Phys. Chem. Lett.
2013, 4, 1060–1064.

(4)      Adams, B. D.; Radtke, C.; Black, R.; Trudeau, M. L.; Zaghib, K.; Nazar, L. F. Energy Environ. Sci.
2013, 6, 1772–1778.
The Effect of Mechanical Property on the Life Cycle Ability of Batteries
Authors: Asayesh-Ardakani Hasti , Nie Anmin , Yuan Yifei , Shahbazian-Yassar Reza
Published: February 2020

Hasti Asayesh-Ardakani1, 3, Anmin Nie1
, 3, Yifei Yuan2, 3 and Reza Shahbazian-Yassar1, 2,
3

1Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49933-1295, USA

2Department of Material Science and Engineering, Michigan Technological University, Houghton, MI 49933-1295, USA

3Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL60607-7059, USA

Using sodium as a potential charge carrier ion for rechargeable batteries has attracted attention of many researchers since Na-ion batteries are more eco-friendly and affordable due to much more abundance of sodium over lithium on earth.  Another considerable issues are performance and cyclability of batteries. The anode materials usually experience large volume changes through the ion insertion and extraction. This volume change and lithium embrittlement causes cracks and loss of contact in the anode material, which ultimately causes the failure of battery. Here, we investigated and compared the structural and mechanical changes of ZnO nanowires during sodiation and lithiation by using in situ transmission electron microscopy. The cracks were created upon the first lithiation process of single crystalline ZnO nanowire. The lithiated ZnO nanowire shows multiple glassy domains, which has low strength and ductility. This results in poor cyclability of battery. On the other hand, ZnO nanowire after sodiation show dislocations on the surface of nanowire that results in more ductility of sodiated nanowire rather than lithiated one. This direct comparison demonstrates the critical role of anode material’s mechanical properties on failure mechanism and cyclability of Li/Na-ion batteries.
When Is a Battery Starting to Operate Environmentally Positive? Comparison of Storage with Pb-Acid and Li-Ion Technology: Life Cycle Analysis, CO2 Footprint and Balance, and Overall Sustainability
Authors: Pettinger Karl-Heinz , Dong Winny
Published: February 2020

In this talk the results of a study comparing Pb-acid and Li-ion batteries as power storage buffers for residential applications will be presented. The study is organized as an overall comparison, highlighting many production factors, in addition to the  common financial issues.  It was conducted in cooperation between the University of Landshut and California State Polytechnic University, Pomona. A cradle-to- grave life-cycle analysis of both the Li-ion and the Pb-acid battery is presented. The energy demands for production of cells in both technologies are analyzed for the single production steps. The energy needed and the CO2 generated in the production of both types of cells and batteries is compared to the energy saved and the reduction of CO2 emitted through the usage of each type of battery. The detailed analysis of these two popular technologies provides critical information as residential solar systems become

more common. They are compared to their real sustainability in a homestorage photovoltaic buffer application.

The storage of electricity generated by photovoltaics battery is performed by battery systems with a typical capacity between 5 and 20 kWh. In this application Lead-Acid an Lithium-Ion batteries are the most common storage technologies. The storage of electricity generated by a 10 kWp PV-generator in combination with a 7,5 kWh battery is analyzed on different levels. The necessary primary energies for

 

Cell production

Production of the Battery System

Transport to the customer

are compared for Lithium-Ion and Lead-Acid technology. The Energy required for production of one Wh of Battery Capacity on cell level is in

Li-ion-Technology              41 kWh

Pb-acid-technology           14 kWh.

The most energy intensive aspect of Lithium-ion battery production is the coating process. The most energy intensive aspect of Lead-acid battery production is the formation process.

Lithium-ion batteries operate nearly 3-times more “energy efficient” with respect to the demand of primary energy for their production. Although Lead-acid cells require much less energy to produce, when usage and system performance are taken into account Li-ion batteries are the winner of this comparison.

It is shown that the ecological amortization in the mentioned home storage application happens after only a few months of operation. The Li-Ion storage system starts “to work green” after 0.6 years and with the Lead-acid storage system after 1.8 years of operation.

Figure 1
Investigations of Doping and Dissolution in Lithium Transition Metal Oxides Using Density Functional Theory Methods
Authors: Liu Cong , Iddir Hakim , Benedek Roy , Curtiss Larry A
Published: February 2020

LiMn2O4 (LMO) has become a promising candidate to replace LiCoO2 as a cathode material in high power Li-ion batteries, due to its ease of preparation, low cost and non-toxicity. However, the performance of LiMn2O4 cathode is limited by capacity fade, particularly at high temperatures. It is believed that the capacity fade of LiMn2O4 is driven by the loss of Mn resulting from the disproportionation of surface Mn3+ with the resultant divalent Mn ions dissolving into stray moisture and electrolyte. In this work, we investigate possible candidate LMO dopants that can inhibit or reduce Mn dissolution. Several dopant-selection criteria are considered, and the electronic structure of the doped LMO will be discussed.
Mathematical Model to Understand Effects of Cell Temperature Gradients on Lithium Ion Battery Performance
Authors: Deshpande Rutooj , Moore William
Published: February 2020

With wide acceptability of lithium ion batteries for electric and hybrid vehicle applications, precise understanding of cell performance at different operating conditions is increasingly important. Cell temperature is often a critical variable determining the cell performance during the vehicle operation. For automotive applications, difference cooling/heating strategies are used to keep the cell operating temperature within the predetermined limits. This ensures safety during cell operations as well as helps cells meet the cell warranty targets. Heat generation and heat rejection by a cell during the operation may result in non-uniform temperature distribution with a cell. These effects are pronounces in large format cells. The variation in local temperature affects the kinetic and transport rates and thus may result in inhomogeneities in the current distribution across the length/breadth of the electrodes. Widely used, Pseudo 2D (P2D) porous electrode models may not be able to accurately predict cell performance with temperature distribution. Here a simple Pseudo 3D model is developed as an extension to the P2D model to understand the implications of the temperature gradient on the cell performance and eventually on the cell life. Differences in cell performance at uniform temperature operation and with cell temperature gradients are highlighted.
Mn3O4/CNT Nanocomposites Derived from Waste Manganese Resources As High Performance Anode Materials for Lithium Ion Batteries
Authors: Zhang Lihua , Wu Sisi , Wan Yi , Huo Yifeng , Luo Yaochong , Lu Zhouguang
Published: February 2020

It is very important to explore cost-effective, high capacity and stable anode materials for lithium ion batteries from earth-abundant resources. Here we report a facile ball-milling method to prepare Mn3O4/CNT nanocomposites from some waste resources like  amorphous manganese oxide from recycled batteries or from electrolytic manganese industry. The obtained Mn3O4/CNT nanocomposites were intensively investigated as anode materials for lithium-ion batteries and supercapacitors. In these Mn3O4/CNTs nanocomposites with a unique bird nest architecture, the CNTs work as electrical wiring branch. This provides electron efficient transport pathway and accommodate a large volume change during the electrochemical reactions. While the ultrafine Mn3O4 nanoparticles grafted onto the CNTs ensure high specific capacity. Therefore, exceptional high capacity (>1000 mAh g-1) and extremely stable cycling were achieved.
Structure Characteristic Evaluation of Triclinic and Orthorhombic LiVOPO4 of Cathode Materials in Lithium Ion Batteries
Authors: Lee Seong-Hun , Ryu Kwang-Sun
Published: February 2020

LiVOPO4 has the stable structure result from stable PO4 unit, high potential of 4.0 V compare with LiFePO4 (3.5 V), and it has a theoretical capacity of 166 mAh g-1, which is slightly lower than LiFePO4 (170 mAh g-1). In addition to this, it appears the high theoretical energy density (664 Wh/kg) as against the 578 Wh/kg for LiFePO4. Based on the spatial arrangement of VO6 octahedral and PO4 tetrahedral units, which host the lithium ions in the interstitial sites of the framework, LiVOPO4 exists different crystallographic phases such as α-, β-. γ-. δ-. ε-, ω- LiVOPO4. Triclinic α-LiVOPO4 and orthorhombic β-LiVOPO4among them has magnificent electrochemical performance. VO6 octahedral was consisted of four oxygen atoms in the equatorial and two oxygen atoms at the axial vertices of the octahedron. The oxygen at the axial has different bond length.

In this study, we compared the physical properties of triclinic α-LiVOPO4 and orthorhombic β-LiVOPO4., This materials were synthesized by the sol-gel method. The starting materials used vanadium oxide, lithium carbonate, ammonium dihydrogen phosphate. The used precursors measured the DSC (Differential Scanning Calorimeter) to confirm the phase transition temperature. And structure analysis of synthesized LiVOPO4 and impurities formation were confirmed through the XRD measurement. Also, SEM (Scanning Electron Microscopy) and EDS (Energy dispersive X-ray spectroscopy) measured to confirm the particle size of synthesized LiVOPO4 and distribution of atoms. And local structure such as bond length, oxidation state, and parameter of unit cell was confirmed by rietveld refinement and XAFS (X-ray Absorption Fine Structure). The Electrochemical Li ion intercalation performances such as EIS (Electrochemical Impedance spectroscopy), CV (Cyclic Voltammetry), CD (charge-discharge), rate capability also evaluated as the cathodes.
High Energy Lithium Cobalt Oxide for Lithium Ion Batteries
Authors: Lu Wenquan , Su Xin , Li Yangxing , Aguesse Frederic , Bareno Javier , Bloom Ira , Sun Chengjun , Liu Qi , Ren Yang , Ishwait Manar
Published: February 2020

High energy density batteries are becoming essential to satisfy the demands of fast growing portable electronic and electric vehicle markets. There are great efforts in the battery community to explore new materials with a high energy density. However, the challenge is formidable and even if potential materials can be identified, it still takes years, if not a decade, to commercialize. Therefore, it is reasonable to investigate modifications of existing materials to improve battery energy density.

LiCoO2, the first commercialized material, is still the most used cathode material to-date due to its simple synthesis process, high energy density, and good cycle life. Conventionally, only a limited amount of its capacity was utilized due to the concern of its structural instability. However, with better understanding of this electrode material, more and more energy has been achieved by pushing its cutoff voltage to higher values without sacrificing electrochemical performance. Currently, LiCoO2 is operated as high as 4.4V in full cells, which is equivalent to 4.45V vs. Li, and yields a specific capacity of 180mAh/g. This is close to a 20% capacity increase compared to the early 140 mAh/g capacity. In this study, we investigated the possibility of increasing the LiCoO2 upper cutoff voltage to even higher voltages, such as 4.5V or even 4.6V, with capacities greater than 190 mAh/g.

It has been well understood that LiCoO2 will go through a phase transition when half the lithium is removed from the structure. This phase transition will affect the stability of its structure and lead to poor cycling performance. Doping is a common method to suppress the phase transition. In order to study the doping effect, aluminum doped LiCoO2 (LCO-A) cathode materials were prepared by ShanShan, China. The electrochemical characterization clearly indicates that the phase transition is suppressed for the doped LiCoO2, which demonstrated excellent cycling performance. Following their electrochemical characterization, the LiCoO2 cathode materials were further studied to examine their chemical composition, morphologies, structure, and surface properties. The results shed further light on the development of high energy LiCoO2.

Acknowledgement

Support from David Howell and Peter Faguy of the U.S. Department of Energy’s Office of Vehicle Technologies Program is gratefully acknowledged. This work was performed, in part, at the Electron Microscopy Center for Materials Research, Center for Nanoscale Materials and Advanced Photon Source, Offices of Science, Offices of Basic Energy, and Offices of Sciences User Facility operated for U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Improved High Voltage Electrochemical Properties and Thermal Stability of LiNi0.6Co0.2Mn0.2 By Li3PO4 Surface Modification
Authors: Lee Suk-Woo , Kim Myeong-Seong , Youn Hee-Chang , Kim Young-Hwan , Kim Jisoo , Kim Kwang-Bum
Published: February 2020

LiCoO2 is the most commercialized in lithium ion batteries (LIBs) for portable electronics because of its high volumetric energy density compared to the other commercialized cathode materials. However, low specific capacity (145 mAh/g @ 4.3 V cut-off) hinders its application to emerging technologies, such as power tool and plug-in hybrid electric vehicles. As a result, layered Ni-rich LiNixCoyMn1
-
x
-
yO2 materials have attracted much attention as promising alternative cathode materials because of their high capacity and relatively low cost. However, Ni-rich layered cathode materials suffer from structural instability by direct contact with electrolyte at high voltage (>4.3V), resulting in poor cyclability, rate capability and thermal instability.

To solve these problems, a lot of researches have been carried out to coat the surface of layered cathode materials using oxide or phosphate, such as TiO2, Al2O3, and Li3PO4.

Among these coating materials, Li3PO4 has attracted a great attention as coating material due to its high ionic conductivity and thermal stability due to strong P=O bonding.

Recently, Zhao et al., reported on the Li3PO4 coating on LiFePO4 cathode material, but they used Li3PO4 nano particle as a coating material, resulting in non-uniform coating. Also, Xiong et el, tried to coat the Li3PO4 on LiNi0.8Co0.1Mn0.1O2 cathode material using the reaction between (NH4)2HPO4 and lithium residues, but the Li3PO4 coating layer is not confirmed.

In this study, we report on the synthesis of Li3PO4-coated LiNi0.6Co0.2Mn0.2O2 using a citric acid assisted sol-gel method in which nm-thick Li3PO4 layer was uniformly coated on the LiNi0.6Co0.2Mn0.2O2. It exhibited improved cyclability at high voltage (4.7V) and rate capability than those of bare LiNi0.6Co0.2Mn0.2O2. In addition, Li3PO4-coated LiNi0.6Co0.2Mn0.2O2showed improved thermal stability at elevated temperature.

More details on the synthetic procedure, electrochemical and physical properties will be presented at the meeting.
Crystallographic Analysis of Structural Changes in Lithium Nickel Manganese Cobalt Oxides at Different Stages of Lithiation
Authors: Fröhlich Katja , Kahr Jürgen , Abrahams Isaac , Trifonova Atanaska
Published: February 2020

Mixed transition metal oxides are among the most promising cathode materials for lithium ion batteries. The high specific capacity, low cost and thermal stability makes Li(Ni1/3Mn1/3Co1/3)O2, so-called NMC, an excellent material for power tool applications. Therefore, main leading battery manufacturer focus on the combination of these three transition metals to combine the strengths of each of them [1].

The development and design of battery materials require deep understanding of the relations between chemistry, structure and its properties. Nowadays, the commercialized NMC can only reach around 60 % of its theoretical capacity when cycled up to 4.2 V. Higher specific capacities might be reached when the upper voltage limit is raised up to 4.5 V [2], but the lifetime of the cathode then decreases drastically. The deintercalation of more than 0.6 moles of lithium in the charge process of the battery leads to irreversible capacity losses.

Lithium nickel manganese cobalt oxides with different transition metal ratios were successfully synthesized via coprecipitation route. The cathode materials were characterized physico- and electrochemically and the composition was confirmed via inductive coupled plasma atomic emission spectroscopy (ICP-AES).

Structural changes of non-symmetric NMC compounds at different stages of lithiation were recorded using x-ray diffraction. The resulting patterns were analyzed and the structures refined using the Rietveld method implemented in the GSAS (General Structure Analysis System) package [3].

The same procedure of crystallographic characterization of the NMC structure was carried out for different transition metal ratios cycled up to 4.5 V. The results are presented and comparison between symmetric and non-symmetric lithium nickel manganese cobalt oxides will give better insight into structural changes at higher voltages and the relation to their compositions.

Acknowledgement

This work was financially supported by the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit) and the Austrian Research Promotion Agency (FFG).

[1]     N. Yabuuchi, T. Ohzuku, Journal of Power Sources 119-121 (2003): 171-174

[2]     Q. Yu, Z. Chen, L. Xing, D. Chen, H. Rong, Q. Liu,W. Li, Electrochimica Acta 176 (2015): 919-925

[3]     A. C. Larson, R. B. Von Dreele, Los Alamos National Laboratory Report, No. LAUR-86-748, (1987)
On the Asymmetry of Charge-Discharge Curves of Lithium-Ion Battery Electrode Materials
Authors: Hall Florian , Wussler Sabine , Buqa Hilmi , Bessler Wolfgang G.
Published: February 2020

One of the most auspicious materials for lithium-ion batteries is Nickel cobalt aluminum oxide (NCA). It provides a high capacity, excellent rate capability and low costs [1]. NCA-electrodes and NCA-based lithium-ion batteries have been observed to exhibit a distinct discharge/charge asymmetry in the low SOC regime, shown both in the published literature [2,3] and in our own full-cell (see Figure) and half-cell experiments.

The origin of this behavior has not yet been explained. Using elementary kinetics theory, we show that the asymmetry is caused by a two-step electrochemical reaction mechanism, where charge transfer is associated with electroadsorption of lithium ions from the electrolyte onto the NCA surface (s) according to

Li+(electrolyte) + e–+ (s) ⇄ Li(s),

followed by incorporation into the bulk active material,

Li(s) + V[NCA] ⇄ Li[NCA] + (s).

The overall reaction is dominated by the surface reaction, because of the limited surface spots. Both thermodynamics (via Nernst equation) and kinetics (transition state theory) of the electroadsorption reaction are nonlinearly influenced by surface concentrations of the involved surface species. Surface coverages, in turn, nonlinearly depend on the thermodynamics of the incorporation reaction, where different assumptions for the surface thermodynamics and bulk intercalation range are shown to cause different levels and shape of asymmetry.

The asymmetry is shown to prevail in commercial NCA/LTO pouch cells, leading to a strong temperature and rate sensitivity of the cell capacity. Newman-type numerical models that take the two-step behavior into account are able to reproduce experimentally-observed cell discharge/charge measurements over a wide range of temperature and C rate.

The Figure shows a) the experimental charge-discharge curves of a commercial cell in the low SOC regime, b) simulations using a standard model with single-step Butler-Volmer kinetics, and c) simulations using an extended model with an elementary kinetic two-step mechanism.

Literature:

1.   W.-S. Yoon, K. Y. Chung, J. McBreen, and X.-Q. Yang, “A comparative study on structural changes of LiCo1/3Ni1/3Mn1/3O2 and LiNi0.8Co0.15Al0.05O2 during first charge using in situ XRD,” Electrochemistry Communications 8, 1257–1262 (2006).

2.   P. Albertus, J. Christensen, and J. Newman, “Experiments on and Modeling of Positive Electrodes with Multiple Active Materials for Lithium-Ion Batteries,” J. Electrochem. Soc. 156, A606 (2009).

3.   Y. Xu, X. Li, Z. Wang, H. Guo, and B. Huang, “Structure and electrochemical performance of TiO2-coated LiNi0.80Co0.15Al0.05O2 cathode material,” Materials Letters 143, 151–154 (2015).

Figure 1
Amorphous Carbon-Coated Si Alloy As Long-Term Cyclability Anode Material for Lithium Ion Batteries
Authors: Cho Jong-Soo , Kim Jae hyuk , Suh Soon sung , Kim Seung Wan , Kwon Se Man , Park Yong Tae , Lee Ki Kang , Jeon Hee Sang , Chu Yeon-Yi , Lee Jin , Cho Sung-Jin , Jeong Je Jun , Kim Seul Cham , Oh Kyu Hwan
Published: February 2020

This presentation reports Si alloy anode materials developed for commercial application for lithium ion batteries(LIBs). This Si alloy material consists of amorphous Si embedded metal-silicide anode materials. It’s synthesized by using mechanical milling. Our alloy have attained a high capacity(energy), high initial efficiency, excellent power property, high coulombic efficiency during cycling. However, sudden failure problem have happened with less FEC contained electrolyte sometimes before 200 or 300 cycles. In an attempt to overcome this major issue, we prepared amorphous C-coated Si alloy, and optimized C-coating process conditions like temperature, carbon contents. As a result, we could improve sudden failure problem with our new amorphous C-coated Si alloy. This new Si alloy’s performance suggests a promising approach to commercial Si anode materials with high capacity.
Electrochemical Properties of Single Crystalline LiMn2O4 cathode Thin Films
Authors: Hendriks Theodoor Anton , Monteiro Cunha Daniel , Singh Deepak , Huijben Mark
Published: February 2020

Most commercial rechargeable lithium-ion batteries deliver energy densities far below their theoretical values. The key problem determining these limitations are the slow electrode process kinetics, low ionic diffusion and low electronic conductivity, particularly at the electrode-electrolyte interfaces. Mastering control of these interfaces is identified as a grand challenge in battery research, even more important than designing new electrode and electrolyte materials.

All-solid-state microbatteries facilitate miniaturization, which will create more flexibility for the design of stand-alone microelectronic devices with enhanced applicability due to the avoided leakage risks. However, the successful application of all-solid-state microbatteries depends strongly on the enhancement of energy density and lifetime. The cycle-life and lifetime are dependent on the nature of the interfaces between the electrodes and electrolyte, whereas safety is a function of the stability of the electrode materials and interfaces. Therefore, perfect control on the interfacial properties between the electrodes and electrolyte is needed, but remains a great challenge.

The crystal structure of the electrode, electrolyte matrix and their interfaces will determine the lithium diffusion mechanism within the complete structure, which will eventually be crucial for the battery performance. To study the variation in electrochemical properties for the different crystalline directions in the spinel crystal structure of the LiMn2O4 cathode material, thin films have been grown by pulsed laser deposition. Control over the deposition parameters (temperature, pressure, etc.) in combination with variation in crystal orientation of the Nb-doped SrTiO3 substrates (e.g. (001), (111) and (110)) enabled the formation of single crystalline LiMn2O4 thin films.

The local variations in surface morphology and phase composition have been analyzed by Atomic Force Microscopy (AFM) and X-Ray Photoelectron Spectroscopy (XPS), while the variations in structural properties have been characterized by X-ray Diffraction (XRD). Electrochemical performance was studied by impedance spectroscopy.

In our study we have investigated the relation between the electrochemical performance and the crystal orientation in LiMn2O4 cathode thin films. This provides important insight for the subsequent creation of solid-state cathode/electrolyte interfaces with controlled crystal structures for optimal interfacial properties.
Novel Li-Titanate Anode Thin Film Structures for Li-Garnet All Solid State Batteries
Authors: Pfenninger Reto , Afyon Semih , Garbayo Inigo , Struzik Michal , Rupp Jennifer L. M.
Published: February 2020

Next generation energy storage devices for stationary as well as mobile electronics will not only need high gravimetric and volumetric capacity, but also long term stability even in rough environments at elevated temperature. Here, all solid state batteries based on Li-garnet structures are shown as interesting model systems that: i.) can partially use industrial waste heat to increase charging times (increased Li+ diffusion) for stationary, ii.) can integrate new high capacity electrode materials which show conventionally a low stability in standard liquid/polymer based Li-batteries, iii.) are easy transferrable to model thin film battery structures for powering of portable electronics. Going all-solid-state opens up completely new pathways for chip integration and downscaling to the sub-micron range for high energy densities to battle supercapacitors. From a materials perspective, cubic garnet Li7La3Zr2O12-based structures are among the fastest conducting solid state electrolytes[1]. Moreover, their inherent compatibility with metallic Lithium, stability in a wide voltage range as well as their Arrhenius-activated conduction mechanism support their prospering interest for all solid state large-scale and future microbatteries. On the electrode side, Li4Ti5O12 is known as one of the most stable anode material due to its remarkably low volume expansion upon lithiation/delithiation and its good cycle performance [2].

We hereby report our latest progress on nanostructuring different promising anode thin films of Li4Ti5O12 / TiO2 mixed-phase deposited by pulsed laser deposition and constructed bilayer half-cells batteries systems with Li7La3Zr2O12 pellets as the electrolyte. Rate capability studies as well as galvanostatic cycling of this system showed promising initial capacity and acted as a case study for the well-known Li4Ti5O12 thin film anode, shown its good compatibility with the investigated solid garnet electrolyte. Near-order phenomena could be tracked by Raman spectroscopy and gave insight into the process of lithiation and delithiation. To the best of our knowledge, no such study has yet been reported in literature. However, degradation and ageing effects still remain challenging and will be discussed.

References

[1] Thangadurai et al., Chemical Society Reviews 43(13), 4714.

[2] Kumantani et al. Applied Physics Letters 101(12), 123103.
Electrochemical Studies of Carbon Nanotube-LiFePO4 Nanocomposite Cathode for High-Capacity Lithium-Ion Batteries
Authors: Sun Xiangcheng , Feng Kun , Chen Zhongwei , Cui Bo
Published: February 2020

LiFePO4 nanoparticles were incorporated with multi-walled carbon nanotubes (CNTs) via a facile one-step polyol process at low temperature. CNTs were uniformly embedded into LiFePO4 particles and formed a conductive network to enhance the electrochemical performance of the CNT-LiFePO4 nanocomposite cathode. Structural composition and morphology of the composite were investigated in details by X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM, TEM). The electrochemical properties were analyzed in the voltage of 2.0 and 4.0 V by charge/discharge testing and cyclic voltammetry. Primary experimental results showed that these CNT-LiFePO4 nanocomposite cathodes exhibited enhanced electrochemical performance with both high capacity and good reversibility which has been clearly demonstrated in the Fig. 1.

Figure 1
Nanostructured Lithium Transition Metal Orthosilicates Made By Flame Spray Pyrolysis
Authors: Wagner Nils P. , Vullum-Bruer Fride , Svensson Ann Mari
Published: February 2020

The polyanion based materials gained significant interest since the discovery of LiFePO4 as a safer cathode material in 1997 [1], and of Li2FeSiO4as a new Li-battery cathode material in 2005 [2]. Lithium transition metal orthosilicates are promising cathode candidates since they allow Li extraction/insertion beyond one Li-ion per formula unit. Additionally, they consist of cheap, environmentally benign and abundant elements [3]. However, these materials suffer from poor conductivity, ionic as well as electronic, which demands the need for nanostructuring and conductive coatings. And in order for the orthosilicates to be real competitors to current commercial cathode technology, it is vital to find cost efficient and scalable methods for production of nanosized powders.

Here, we present a time-efficient and scalable aerosol combustion method with subsequent annealing, leading to nanoscale and carbon-coated Li2FeSiO4 and Li2Fe0.5Mn0.5SiO4. Using liquid-feed flame spray pyrolysis, we demonstrate synthesis of highly phase pure materials in a relatively short time. The work shows the importance of synthesis parameters such as precursor concentration, and its effect on particle size, degree of agglomeration, and long-term performance. In the case of Li2FeSiO4, the optimised precursor concentration yielded particles of about 30 nm, which delivered an initial discharge capacity of up to 150 mAhg-1 at 60 °C and C/20. Furthermore, over 50% of the capacity is retained at a high rate of 5C, and long-term cycling showed outstanding capacity retention of over 90% after 300 cycles at a moderate rate of C/2. Li2Fe0.5Mn0.5SiO4 on the other hand,was shown to suffer from a severe capacity fade, and upon prolonged cycling the redox activity can be attributed solely to Fe.

[1]    Padhi A. K., Nanjundaswamy K. S., Goodenough J. B., J. Electrochem. Soc, 1997, 144, 1188-1194.

[2]    Nyten A., Abouimrane A., Armand M., Gustafsson T., Thomas J. O., Electrochemistry Communications, 2005, 7, 156-160.

[3]    Saiful Islam M., Dominko R., Masquelier C., Sirisopanaporn C., Armstrong A. R., Bruce P. G., J. Mater. Chem., 2011, 21, 9811-9818
Nanoscale Multiphase Lithium Deficient Lix(Ni1/3Mn1/3Co1/3)O2 (x<1.0) As High-Performance Cathode Material for Advanced Li-Ion Batteries
Authors: Uddin Md-Jamal , Alaboina Pankaj Kumar , Cho Sung-Jin
Published: February 2020

A high-performance lithium deficient Lix(Ni1/3Mn1/3Co1/3)O2 (x<1.0) cathode material with multiphase structure in primary particles has been synthesized by high-temperature sintering of metal hydroxide precursors with lithium carbonate. The metal hydroxide precursors were synthesized by a commercially common spray drying method, and the nanoscale morphology of the hydroxide precursors is translated to the synthesized cathode material during solid state sintering. The synthesized cathode material (hereafter denoted as MPC) were studied for their structure, morphology, and composition. X-ray diffraction pattern and scanning electron microscopy revealed a nanoscale, multiphase, lithium deficient Lix(Ni1/3Mn1/3Co1/3)O2 cathode material. Energy dispersive spectroscopy and inductive coupled plasma – optical emission spectroscopy results confirmed the metal ratios and composition. High-resolution transmission electron microscopy and selective area electron diffraction data, from the cross section of the particle after focused ion beam milling, revealed the formation of a layered structure (space group: R-3m) in the core, and a mixed structure consist of spinel (space group: Fd-3m) and layered structure at the surface. Half cells (2032-type coin cell) made with commercial Lix(Ni1/3Mn1/3Co1/3)O2 (x>1.0, Umicore) (hereafter LPC) and MPC showed very high improvement in the rate capability and cycle performance for MPC which is attributed to the high voltage structural stability of the multiphase structure.
Single Wall Carbon Nanotube-Containing PVA Based Carbon Nanofibers for Lithium Ion Battery Anodes
Authors: Serife Pampal Esra , Stojanovska Elena , Uzun Davut , Kilic Ali
Published: February 2020

Lithium ion batteries have increasing importance due to the urgent demand for widespread applications in electric/hybrid vehicles, electronic devices, and the grid energy storage.  Graphite is one of the most commonly used anode material with low theoretical capacity(372mAh/g) and limited rate capability. In order to improve battery Li-ion storage capacity many researchers have investigated different carbonaceous anode materials with various configurations. Among them, carbon nanofiber is of particular interest for providing high capacity and cycling stability due to its high surface area, porous structure and high electric conductivity which not only shorten the lithium ion path through the electrode but also provide large electrode/electrolyte interface for the charge-transfer reaction properties.

Carbon nanofibers can be directly used as free standing and binder free anodes. There are several nanofiber production methods, among which electrospinning is the most promising due to its simplicity and versatility. Carbon nanofibers can be produced with different precursors such as Pitch, polyacrylonitrile(PAN), polyvinypyrrolidone(PVP), polyvinyl alcohol(PVA) etc. Polyvinyl alcohol is a promising material due to its water soluble and environmentally friendly character.

In this study we report a method to produce free-standing binder free single wall carbon nanotube containing carbon nanofibers as anode for lithium ion battery. Composite nanofibers prepared via electrospinning of single wall carbon nanotubes (SWCNT) dispersed into polyvinyl alcohol solution, followed by iodination at 100°C and heat treatment in an inert atmosphere at 800°C. Carbon nanotubes were added to the polymer solution in different concentrations 0,1% , 1%, and  5 %. An increase of the carbon nanotube concentration in the fibers led to carbonized nanofiber mats with increased electrical conductivity.  TGA and Raman analyses showed that carbon nanotubes presence improves the carbon yield of the mats and their handleability. Galvanostatic cycling tests of half cells revealed that addition of carbon nanotubes improves battery capacity. We attribute the capacity increase of the composite nanofibers to the carbon nanotubes structure. Moreover carbon nanotubes increased the handleabilitiy of the mat which is crucial for freestanding, binder free anode materials.