bluuebunny/crossref_metadata_2025 huggingface dataset:
Doped Si Nanoparticles As a High Performance Anode for Li Ion Batteries
Authors: Li Yan , Xiao Lisong , Ren Yang , Schulz Christof , Wiggers Hartmut , Amine Khalil , Chen Zonghai
Published: February 2020

Graphite, with a theoretical storage capacity of Li ions with an equivalent of 372 mAh/g, has been used as anode in commercial lithium ion battery for decades. Due to the advancement of electronic portable devices and the development of electrical vehicles, higher capacity and energy density anode materials are needed. Silicon, which has a theoretical capacity 3579 mAh/g, has been explored as the next generation anode material. Being different from graphite, Li has an alloying reaction with Si instead of intercalation, which leads to severe volume expansion (as much as 370%) during charging.  The repeated volume change during cycling can destroy Si particles and the surrounding solid electrolyte interphase and leads to capacity fade. Reducing the size of Si particles has been proven as an effective way to alleviate decomposition. Therefore, Si has been synthesized as thin film, nanowires, and nanoparticles to improve its cycling stability. For nanosized Si, the capacity retention is satisfying even with high amounts of Si contained in the electrode. In this work, nitrogen doping of silicon is used to further improve the cycling performance of the Si nanoparticles. It is found that N-doping modifies the crystallization of Si nanoparticles leading to amorphous Si nanoparticles with high nitrogen concentration. At the same time, with increasing N doping concentrations, the specific capacity decreases. However, better capacity retention, rate performance, and reduced side reactions can be achieved. It is demonstrated that high-performance Si-based anode material can be obtained by carefully controlling doping nitrogen in Si nanoparticles.
Synthesis and Characterization of Electrospun NANO LiMn2O4 for Cathode Material Application
Authors: Kufian M.z , Arof A.k , Aziz N. , Teo L. P. , Buraidah M. H. , Mat Nor N. a. , Natarajan T. S.
Published: February 2020

In this work, LiMn2O4 powder synthesized by sol-gel method using tartaric acid as chelating agent was mixed with polyethylene oxide (PEO) to form a solution of LiMn2O4/PEO. The polyethylene oxide/lithium manganese oxides (LiMn2O4/PEO) solution in ethanol was electrospun to produce cathode nanofiber materials. The effect of different concentrations of LiMn2O4 (5%, 7% and 9%) on fiber formation was also studied. After calcination, nanoparticles of LiMn2O4 with less than 100 nm were successfully obtained. The structure and properties of fabricated electrospun LiMn2O4 nanofiber and nanoparticles were studied using field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). Electrospinning succeeded in forming clear interwoven spider web nanofiber with no bead formation. The results showed that the particle size increased with increasing LiMn2O4 content. Conductivity studies show that the very small particle size resulted in low conductivity performance. The cell with configuration Li/1M LiPF6 in EC/DMC/ LiMn2O4 has given an open circuit voltage (OCV) of ~ 3.0 V.
Safe Lithium-Ion Batteries? Predicting Performance over a Range of Operating Conditions
Authors: Francis Candice , Best Adam Samuel , Lammas Andrew , Sammut Karl
Published: February 2020

Electrochemical-thermal coupled modelling of lithium-ion batteries is used to simulate battery performance. Modelling can be used to investigate the effects of different materials and design parameters on battery performance and safety. Numerous models exist for lithium-ion batteries1 from microscopic through to module scale simulations. Majority of these models simulate cell performance under normal charge and discharge operation. Generally these models do not accurately predict cell behaviour outside of normal conditions, such as at high temperatures. Operating lithium-ion cells at high temperatures can lead to an internal thermal event and ultimately cell failure. A number of models have been developed to simulate cell behaviour outside normal conditions however these models do not include the performance of cells during normal operation. A model that simulates cell performance over a range of conditions is necessary to make an informed decision regarding material and design changes. This work aims to combine two existing models to create a new model for simulation of cell performance under normal and high temperature conditions.

Two existing models were chosen to create the new model. The models were selected to meet the following criteria: 1) single cell model 2) stacked plate configuration 3) individual component layers modelled (no homogeneous core assumption) 4) includes temperature dependent material properties (or able to be included). The first is a 1D electrochemical-thermal reduced order model developed by Gambhire et al.2 for simulation under normal charge and discharge operation. The second is a 1D electrochemical-thermal coupled model developed by Wang et al.3 for simulating internal thermal events including decomposition reactions for each cell component. Key aspects of both models have been used to create a new model implemented in COMSOL Multiphysics®. The new model is expected to more accurately describe cell behaviour over a range of conditions. The results of this study will be presented at the conference.

Acknowledgments: The authors acknowledge the funding support provided by the ARC Research Training Centre for Naval Design and Manufacturing, PMB Defence Engineering, and the CSIRO Manufacturing High Performance Metal Industries Program.

References:

D. Miranda, C.M. Costa, S. Lanceros-Mendez, J. Electroanal. Chem, 739, 97 (2015).

P. Gambhire, N. Ganesan, S. Basu, K.S. Hariharan, S.M. Kolake, T. Song, D. Oh, T. Yeo and S. Doo, J. Power Sources, 290, 87 (2015).

S. Wang, L. Lu and X. Liu, J. Power Sources, 244, 101 (2013).
Improving Stability of High Voltage Cathodic Materials Using Polyfluorinated Additives and Electrolyte Solutions
Authors: Sun Haoran , Li Yizhi
Published: February 2020

High capacity and high voltage cathodic materials are key to increase the power and energy densities of rechargeable batteries.  The cause of instability of the high voltage cathodic materials is that these cathodic materials irreversibly react with the electrolyte solutions during charging/discharging and/or storage processes.  As a result of such reactions, the cathodic materials decompose to non-electrochemical active materials, and the same time electrolyte solution decomposes to gaseous molecules, leading to the batteries dry out condition, a deadly condition for rechargeable batteries.  Fundamentally, there are approaches to solve this problem as demonstrated in the literature: 1) preparation of new electrolytes and solvents that are thermodynamically stable, i.e. their first oxidation and first reduction potential are outside the potential of anodic redox couple (e.g. Li+/Li) and the potential of the cathodic redox couple (e.g. Li(1-x)CoPO4/LiCoPO4); 2) discover new electrolytes and solvents systems that are kinetically stable, i.e. the electron transfer rates between electrolyte solution and both cathodic and anodic materials are slow, providing large overpotentials for those unwanted electrochemical reactions; 3) addition of new reagents (e.g. additives) into the electrolyte solutions to form an interfacial layer (e.g. SEI layer) on both cathodic and anodic materials, resulting slow electron transfer rate between electrolyte solution and both cathodic and anodic materials, providing, again, large overpotentials for those unwanted electrochemical reactions.  

               Many works have done over the past decade or so to improve the stability of the cathodic materials.  Due to synthetic challenges possessed in preparation of thermodynamically stable electrolyte solutions, discovering new additives that can slow down the ET processes becomes another popular approach.  Here we report the use of new polyfluorinated additives that can improve the stability of high voltage cathodic materials (e.g. LiCoPO4) by slowing down the ET process between electrolyte solution and the cathodic materials during the charging/discharging processes by forming a fluorinated protective SEI layer.  The high electronegativity of fluorine results in exceptionally strong bonds to carbon (bond dissociation energy (BDE) C-F = 110-126 kcal/mol). Furthermore, fluorine substitution results in an increase in the C-C bond energy in fluorocarbons compared to the corresponding hydrocarbons.  The preformed fluorinated protective SEI layer on cathodic material surface either prevents or slows down the ET process between commonly used electrolyte solutions (i.e. PC with 1.0 M LiPF6).  We find that such protective SEI layer can be pre-formed when treating the cathodic materials with polyfluorinated additives.  This result indicates that pre-modification of cathodic materials is possible to increase the stability and compatibility with the electrolyte solution.
The Effect of Al2O3 on the Sintering of Garnet-Type Li Ion Conductors Li6.5La3Zr1.5Ta0.5O12
Authors: Wang Yuxing , Yan Pengfei , Xiao Jie , Deng Daniel , Lu Xiaochuan , Sprenkle Vincent
Published: February 2020

It is widely recognized that Al plays a dual role in the fabrication of garnet-type Li ion conductors, i.e., a dopant that stabilizes the cubic structure and a sintering aid that facilitates the densification. However, so far, the sintering effect of Al2O3 has not been well-understood due to the common practice of ‘unintentionally’ introducing Al from crucibles during the sintering process. In this study, the sintering effect of Al on the phase composition, microstructure and ionic conductivity of Li6.5La3Zr1.5Ta0.5O12 was investigated by using an Al-free crucible and intentionally addition of various amounts of γ-Al2O3.

XRD analysis showed that all sample have pure cubic phase regardless of the quantity of γ-Al2O3 addition up to 0.3 mol per formula unit of LLZT0.5. While the sample with no sintering aid cannot be successfully densified at 1100 °C, 0.05 mol of Al sintering aid can effectively enhance the densification. The morphology is characterized by small densely-packed polygonal grains. Further addition of Al sintering aids leads to rapid grain growth and increased secondary phases which are detrimental to the densification process. The drastically different morphology of samples with different Al contents are explained by the liquid phase sintering mechanism based on the Li2O-Al2O3 eutectic system. Our EDS analysis showed that Al prefers to stay at the grain boundary rather than enter the garnet lattice. Uneven Al distribution in high Al-content samples is observed as Al predominately exists in small, concentrated area as secondary phases. Transport properties characterized by impedance spectroscopy are largely consistent with the morphology results that the sample with 0.05 mol of Al showed the best densification and a maximum total ionic conductivity of 0.5 mS/cm was achieved. Therefore, a 0.05 mol of Al in the form of γ-Al2O3 is the optimal quantity of sintering aids for this system. This study clarifies the role of Al as sintering aids and will be useful for harnessing the sintering power of Al in a controllable manner.

Acknowledgment

This work was supported by the U.S. Department of Energy’s (DOE’s) Office of Electricity Delivery & Energy Reliability (OE), U.S. Department of Energy Wind and Water Power Technologies Office and the U.S. Army Corps of Engineers, Portland District. We appreciate the useful discussions with Dr. I. Gyuk of the DOE-OE Grid Storage Program.

Figure 1
Electrolyte Composition Influence on Oxygen Reduction and Evolution in Li-Air Cells
Authors: Gittleson Forrest S , Jones Reese E , Ward Donald K , Foster Michael E. , Anstey Mitchell R
Published: February 2020

The lithium-air battery is a promising next generation energy storage technology, yet the current combinations of electrolytes and electrodes have been unable to demonstrate long-term efficient cell cycling. Major issues include the decomposition of electrode and electrolyte materials and high overpotentials for the oxidation reaction. While there is significant work exploring the possibility of catalyzed electrodes to reduce cell overpotentials and encourage reversibility, there is a lack of understanding about how to select appropriate complementary electrolyte systems. In this study we employ data from hundreds of Li-air cells to reveal meaningful relationships between electrolyte composition (solvent, salt, oxygen solubility and concentration), oxygen reduction kinetics and mass transport properties. Data from practical coin-type cells are compared to fundamental studies using flat disc electrodes to prove the validity of the method. Findings are supported by molecular dynamics simulations to elucidate the interaction of various electrolyte components. The relationships derived in this work form necessary criteria for downselecting electrolyte systems with the most desired properties.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
Cathode Materials for Rechargeable Mg and Ca Batteries
Authors: Lipson Albert L. , Kim Soojeong , Proffit Danielle L. , Han Sang-Don , Pan Baofei , Lapidus Saul , Sa Niya , Liao Chen , Burrell Anthony K. , Vaughey John T. , Ingram Brian J.
Published: February 2020

Batteries based on magnesium or calcium metal anodes have the potential to achieve energy densities exceeding current Li-ion batteries.  However, there are major challenges to overcome to make such a battery a reality.  One challenge is that currently no cathode materials have been identified that have sufficient energy density for a practical magnesium or calcium based battery.  Towards the end of finding higher energy density cathode materials, this poster presents two different materials approaches for the successful incorporation of Mg and Ca.  In particular, materials based on a Prussian blue type structure and with a polyanionic layered structure will be discussed.  Results presented include cycling performance, X-ray diffraction and X-ray based spectroscopies that prove intercalation of both Mg and Ca.  Comparing these classes of materials to others that have been shown to successfully intercalate Mg, yields insights into what makes a material a good candidate for future multivalent cathode research.  With these design principles guiding the search, a material that can achieve high energy densities for Mg or Ca chemistry can hopefully be found.
Synthesis of TiOx Nanotubular Arrays with Oxygen Defects As High-Performance Anodes for Lithium Ion Batteries
Authors: Chi Shang-Sen , Fan Li-Zhen
Published: February 2020

As a promising safe electrode material for high-power lithium ion batteries, the specific capacity of TiO2 anode up to date is still limited. In this work, we have demonstrated a facile electrochemical anodization for TiOx
nanotubular arrays of oxygen defects in the nitrogen atmosphere. In comparison with those fabricated in air condition, the as-prepared nanotubular arrays present much reduced impedance with oxygen defects, which allow fast electronic and ionic transport in the TiOx
nanotubular arrays. The binder-free anode based on the as-prepared TiOx
nanotubular exhibited the record-setting capacities (395, 325, and 235 mAh g-1 at 0.2 C, 1 C and 10 C, respectively) achieved in the TiO2-based anode materials, therefore approaching state-of-the-art for TiO2 electrodes in the lithium ion batteries.

Reference

[1] Li-Zhen Fan, Shang-Sen Chi, Lu-Ning Wang, Wei-Li Song, Min He, Lin Gu. Synthesis of TiOx Nanotubular Arrays with Oxygen Defects as High-Performance Anodes for Lithium-Ion Batteries. ChemElectroChem, 2015, 2(3): 421-426.

Figure 1
Operando Mössbauer Spectroscopy for Li- and Na-Ion Batteries Investigations
Authors: Sougrati Moulay-Tahar , Jumas Jean-Claude , Stievano Lorenzo
Published: February 2020

In the last decade, a growing number of Mössbauer papers dealing with Li-ion batteries have been published.[1] As for other Material Science branches, this technique is first used in each of the steps leading to the synthesis of innovative materials. Moreover, Mössbauer spectroscopy is almost routinely used for ex situ and in situ investigations of the electrochemical behavior of electrode materials containing the common Mössbauer isotopes 121Sb[2]
119Sn[3] and more frequently 57Fe[4].

In this presentation, we will see how Mössbauer spectroscopy has became indispensable for optimizing the synthesis routes as well as the performances of functional materials. Through examples from our group and other published work, we will illustrate the importance of this technique for batteries study.

Many iron compounds will be presented (LiFe1-xMnxSO4F, LiFe1-xMnxPO4, FeOF etc). Among them, the newest cathode material LiFeSO4F can be given as a pedagogic example showing the role that can be played by Mössbauer spectroscopy in the preparation of this phase, its characterization, and the fabrication of polymeric electrode[5] (figure 1).

Tin containing phases for negative electrode have been intensively studied by Mössbauer spectroscopy. We will browse briefly the published work and finish with the detailed example of TiSnSb (figure 2).

The complementarity of Mössbauer spectroscopy and X-ray diffraction will be illustrated via the examples of the layered oxide Li4FeSbO6
[6] and the mixed valence borophosphate (NH4)0.75Fe(H2O)2 [BP2O8]•0.25H2O[7].

Finally, the 1st examples of the use of synchrotron radiation (SMS, NFS) for batteries investigation will be presented.

References:

[1]           J. C. Jumas and P. E. Lippens, Mössbauer Effect Reference and Data Journal  2010, 33.

[2]           C. Villevieille, C. M. Ionica-Bousquet, J. C. Jumas, and L. Monconduit, Hyperfine Interactions  2008,  187, 71.

[3]           F. Robert, P. E. Lippens, J. Olivier-Fourcade, J. C. Jumas, F. Gillot, M. Morcrette, and J. M. Tarascon, Journal of Solid State Chemistry 2010, 180, 339.

[4]           Ou Mao, R. A. Dunlap, I. A. Courtney, and J. R. Dahn, Journal of The Electrochemical Society 1998, 145, 4195.

[5]           M. Ati, Moulay T. Sougrati, N. Recham, P. Barpanda, J. B. Leriche, M. Courty, M. Armand, J. C. Jumas, and J. M. Tarascon, Journal of The Electrochemical Society 2010, 157, A1007.

[6]       E. McCalla, A. Abakumov, G. Rousse, M. Reynaud, M. T. Sougrati, B. Budic, A. Mahmoud, R. Dominko, G. Van Tendeloo and R. P. Hermann, Chemistry of Materials
2015, JUST ACCEPTED.

[7]       L. Tao, G. Rousse, M. T. Sougrati, J.-N. Chotard and C. Masquelier, The Journal of Physical Chemistry C
2015, 119, 4540–

Figure 1
X-Ray Diffraction and Absorption Spectroscopy Investigations of Lithium Excess Cathode Material
Authors: Murphy Michael J. , O'Hanlon Daniel C. , Croy Jason R. , Balasubramanian Mahalingam
Published: February 2020

Li-excess oxides are promising Li-ion battery cathodes, which when charged to high voltages, can display capacities in excess of the theoretical contribution of the redox active transition metal components. This behaviour has previously been attributed to the partial oxidation of the oxygen sublattice upon Li removal, leading to the release of O2 gas and often accompanied by structural transformations, low coulombic efficiency and poor cycling. Recently, new materials displaying reversible redox behaviour of the oxygen sublattice have been reported, leading to Li-rich cathodes with improved structural stability and alternate charge compensation mechanisms.[1-3]

This study investigates the charge compensation mechanisms and degradation pathways related to oxygen redox activity and oxygen loss in Li-excess cathodes at varying states of delithiation. In order to effectively study the materials in varying states of delithiation, bulk samples free from carbon, binder and electrolyte have been prepared using a range of chemical oxidants and characterised by high-resolution X-ray diffraction, X-ray absorption spectroscopy and electrochemistry techniques.

 [1] Yabuuchi, Naoaki, et al. "High-capacity electrode materials for rechargeable lithium batteries: Li3NbO4-based system with cation-disordered rocksalt structure." Proceedings of the National Academy of Sciences 112.25 (2015): 7650-7655.

[2] McCalla, Eric, et al. "Visualization of OO peroxo-like dimers in high-capacity layered oxides for Li-ion batteries." Science 350.6267 (2015): 1516-1521.

[3] Urban, Alexander, and Gerbrand Ceder. "A disordered rock-salt Li-excess cathode material with high capacity and substantial oxygen redox activity: Li1.25Nb0.25Mn0.5O2." Electrochemistry Communications 60 (2015): 70-73.

Acknowledgment

Support for this work from the Office of Vehicle Technologies of the U.S. Department of Energy, in particular, David Howell and Peter Faguy, is gratefully acknowledged. Sector 20 facilities at the Advanced Photon Source of Argonne National Laboratory, and research at these facilities, are supported by the U.S. DOE, Basic Energy Sciences, and National Sciences and Engineering Research Council of Canada and its founding institutions. The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, 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.
Keeping Cool with Hot Stuff: Safe Collection, Transport and Recycling of Lithium Batteries
Authors: Kross Sebastian
Published: February 2020

With advanced development, e.g. in the field of information technology, telecommunication and e-mobility, the use of lithium batteries is constantly growing and will continue to grow even more during the years to come. Due to their chemical composition and their high energy content, lithium batteries must be handled safely in order to avoid possible hazards. In the context of extended producer responsibility and the taking back of waste lithium batteries this poses a particular challenge for storage, transport and recycling processes.

Objective:

The strict regulatory framework in Europe sets high standards for the transport (ADR) and recycling (European Battery Directive) of waste lithium batteries. As Europe’s leading service provider for the taking back of used batteries GRS Batterien’s mission is to provide practical end-to-end solutions to its 170,000 collection points and to numerous business partners for logistic and recycling services. The aim is to sustain and further improve the proper, safe and compliant battery collection.

Results:

GRS Batterien has developed and implemented innovative processes and products to address the needs of all actors in the reverse supply chain for the taking back of used lithium batteries. As the first player in the market GRS Batterien introduced a special transport packaging and obtained the required approval from competent authorities, allowing the safe and compliant transport of damaged lithium batteries with a gross mass exceeding 500 g, independently of their type or chemistry. A proprietary calculation model is utilized to simulate the energetic and chemical impact of a thermal runaway based on a worst case scenario. Specially trained and equipped 3PL service providers are acting as qualified carriers for damaged and defective lithium batteries, applying a sophisticated quality control process. As a result, GRS Batterien is able to safely collect, ship and recycle lithium batteries of various types - from small portable batteries via batteries from e-bikes or gardening tools through to industrial batteries from electric vehicles or smart energy storage systems.

Conclusions:

During the recent few years GRS Batterien's innovations have significantly improved the collection, the transport and the recycling of lithium batteries. However, additional work will be necessary to further simplify the handling of used lithium batteries. GRS Batterien continues to facilitate improvements, e.g. with R&D activities to develop more efficient recycling technologies or with additional services in related areas.
Reduced Graphene Oxide Wrapped TiNb2O7 Microsphere Anode Piled up with Nanocrystalline Neatly for High Rate Performance and Cycle Stability in Lithium Ion Batteries
Authors: Noh Hana , Lee Yongho , Mun Junyoung , Choi Wonchang
Published: February 2020

Lithium ion battery (LIB) has been interesting in a variety of applications especially for electric vehicles (EV), and hybrid electric vehicles (HEV). Commercialized graphite is used for a representative anode material but has still problems which are the formation of solid electrolyte interphase (SEI) layer and some decomposition in low flat potential. Therefore, SEI is attributed to decrease a capacity of cycle in first few cycle as well as not to transfer lithium ion for high C rate.[1] Due to the lack of potential candidates, TiNb2O7 (TNO) has been investigated as one of the promising next candidates since first proposed as a novel anode material by Goodenough in 2011.[2] TNO anodes display an operational potential larger than 1.0 V (versus Li/Li+), which should avoid the formation of the SEI layer.[2-5] Herein, we reported that wrapping reduced graphene oxide (rGO) around micron sized TiNb2O7 is designed for enhancing the electrochemical properties owing to the greatly conductive material and micro-sized structure. The reduced graphene oxide-wrapped TiNb2O7 microspheres (rGO-TNO MS) have been synthesized by adding formic acid for fabricating microspheres and then wrapped by rGO using cetyltrimethylammonium bromide (CTAB). The formic acid is desirable as an acid catalyst and when tested as an anode material for lithium ion batteries, the rGO-TNO MS shows a high reversible capacity of 242.97 mAh g-1 ­at 0.1C (38.7mAh g-1) and 93.33% of the coulombic efficiency of rGO-TNO MS. Moreover, rGO-TNO MS is specialized for high C rate (100 C) and sustain long cycle stability after 500cycle indicating that is a promising candidates for application in high rate lithium ion storage systems.

References

[1] B. Guo, X. Yu, X.-G. Sun, M. Chi, Z.-A. Qiao, J. Liu, Y.-S. Hu, X.-Q. Yang, J.B. Goodenough, S. Dai,  Energ. Environ. Sci., 7 (2014) 2220-2226.

[2] J.-T. Han, Y.-H. Huang, J.B. Goodenough, Chem. Mater., 23 (2011) 2027-2029.

[3] K. Tang, X. Mu, P.A. van Aken, Y. Yu, J. Maier, Adv. Energy Mater., 3 (2013) 49-53.

[4] X. Lu, Z. Jian, Z. Fang, L. Gu, Y.-S. Hu, W. Chen, Z. Wang, L. Chen,  Energ. Environ. Sci., 4 (2011) 2638-2644.

[5] L. Fei, Y. Xu, X. Wu, Y. Li, P. Xie, S. Deng, S. Smirnov, H. Luo, Nanoscale, 5 (2013) 11102-11107.
Evaluation of the Durability of a Metal-Organic Framework Catalyst in High-Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFCs)
Authors: Miller Todd , Pavlicek Ryan , Mukerjee Sanjeev
Published: February 2020

A non-pgm Metal Organic Framework (MOF) catalyst was evaluated for durability in the high-temperature environment associated with HT-PEMFCs under various conditions. Due to the higher PGM loading typically required for these systems, it is an ideal candidate for research regarding non-PGM catalysts. However, a common issue regarding non-PGM materials is their lack of durability in the low temperature humidified environment of a PEMFC, and until these issues are resolved, it will continue to provide a hindrance towards mass commercialization. Prior work had demonstrated the high performance of this particular catalyst[1], initially in RDE and low temperature fuel cells, and now in HT-PEMFCs. Membrane Electrode Assemblies (MEAs) were tested at 200˚C using a commercial polybenzimidazole (PBI) membrane, and were evaluated under several durability criteria, including constant voltage testing at various potentials (for demonstration of prolonged use), temperature cycling (to mimic startup/shutdown) and corrosion testing to evaluate losses in these primarily carbon-based materials. Early indications demonstrate a highly stable catalyst, as after nearly 40 hours of non-continuous chronoamperometric testing, the fuel cell demonstrated negligible performance losses at 650mV in air at 2.5bar total pressure.

Acknowledgment:

The authors gratefully acknowledge the financial support from the Department of Energy-Energy Efficiency and Renewable Energy, Fuel Cell Technology Office under an Incubator grant (DE-EE0006965). Use of the Stanford Synchrotron Radiation Light source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Use of Beamline 2-2 at SSRL was partially supported by the National Synchrotron Light Source II, Brookhaven National Laboratory, under U.S. Department of Energy Contract No. DE-SC0012704. Use of the beamline 9-BM in Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

References

1. Strickland, K., et al., Highly active oxygen reduction non-platinum group metal electrocatalyst without direct metal-nitrogen coordination. Nat Commun, 2015. 6.

Figure 1
The Effects of Aging on the Tortuosity of Li-Ion Battery Electrodes
Authors: Knight Hannah , Pouraghajan Fezzeh , Wheeler Dean R , Mazzeo Brian A
Published: February 2020

Li-ion battery performance is greatly affected by how well ions travel through the electrodes, which in turn depends on the microstructure of the porous pathways through the electrodes. During cell formation and cycling, changes in the microstructure therefore lead to changes in ionic transport. Currently what causes these changes and their magnitude is poorly understood. Changes in effective ionic conductivity and diffusivity can measured in terms of tortuosity, a dimensionless geometric factor.

This report focuses on the effect of cell assembly and repeated cycling on tortuosity. Using a method previously developed by our group, namely the polarization-interrupt method [1], as well as AC impedance techniques, we were able to determine electrode tortuosity for various electrode films. There is clear evidence of changes in tortuosity during cell formation and cycling steps. These experiments also suggest that electrolyte wetting is a time-dependent process that changes the measured tortuosity.

Three different stages of electrodes were compared: (1) pristine electrodes which had never been in contact with electrolyte, (2) electrodes harvested from newly assembled batteries, and (3) electrodes harvested from cycled batteries. This was done for both anodes and cathodes. In the case of the harvested electrodes, a careful washing procedure is needed to remove Li salt. To validate our results we used two different experimental methods, namely the polarization-interrupt method and a blocking-electrolyte method recently discussed by Gasteiger and coworkers [2].

This research was funded by the BMR program of the US Department of Energy.

[1] Zacharias et al. , J. Electrochem. Soc. 160, A306 (2013).

[2] Landesfeind et al., J. Electrochem. Soc. 163, A1373, (2016).

Fig. 1 SEM/FIB cross section of Li-ion anode showing tortuous paths created by the pores in between active material.

Figure 1
Determination of Mechanical Properties of Battery Films from Acoustic Measurements
Authors: Dallon Kathryn L , Wray Michael , Wheeler Dean R , Mazzeo Brian A
Published: February 2020

Measuring the mechanical properties of lithium-ion battery films, such as thickness and elasticity, is important for predicting and improving homogeneity of the film and performance of the battery. Problems with film heterogeneity could be identified and addressed early on through accurate, non-destructive inspection of the electrode as it is being manufactured. There are several techniques currently used to measure the mechanical characteristics of films, including nanoindentation and laser-induced surface acoustic waves (SAW). However, their use for analyzing battery electrodes is fairly limited.

This research investigates the use of acoustic measurements as an alternative means of non-destructive quality control that could be adapted for on-line use. Mechanical properties of thin films, including elastic modulus and thickness, have been determined using SAW [1,2]. Additionally, acoustic time-of-flight measurements have been taken on complete battery cells to find the state of charge [3]. Here we report on our efforts to measure mechanical properties with SAW. A film under tension is excited to produce a wave. This wave is measured at multiple points along the film to determine the speed of the wave. Because wave dispersion is based on properties such as elasticity and density, we can calculate mechanical properties of the film from the wave speed measurements.

Preliminary results indicate that acoustic tests can demonstrate observable differences between films with different properties, and that changes in the stiffness of the film (such as what happens during the drying process for battery films) can also be detected as a difference in wave speed.

References

[1] Chow et al., Mech. Mater. 91, 333-342 (2015).

[2] Gillinger et al., Appl. Phys. Lett. 108, 231601 (2016).

[3] Hsieh et al., Energy Environ. Sci. 8, 1569-1577 (2015).

Acknowledgements

This work was supported by the U.S. Department of Energy through the BMR program.

Figure: Illustration of apparatus for wave speed measurements of a film.

Figure 1
Predicting the Electrochemical Response of Pseudocapacitor Electrodes Under Realistic Conditions from First Principles
Authors: Keilbart Nathan D. , Okada Yasuaki , Higai Shinichi , Dabo Ismaila
Published: February 2020

Pseudocapacitors are energy-storage devices characterized by fast and reversible redox reactions that enable them to store large amounts of electrical energy at high rates. We simulate the response of pseudocapacitive electrodes under realistic conditions to identify the factors that determine their performance, focusing on ruthenium dioxide as a prototypical electrode material. Electronic-structure methods are used together with a self-consistent continuum solvation model to build a complete database of free energies as the surface of the charged electrode is gradually covered with protons under applied voltage. The resulting database is exploited to compute hydrogen-adsorption isotherms and charge--voltage responses by means of grand-canonical sampling, finding close agreement with experimental voltammetry. These simulations reveal that small changes in the intrinsic double-layer capacitance on the order of 5 μF/cm2 induce considerable variations of as much as 40 μF/cm2 in the overall interfacial pseudocapacitance.
Engineering Solutions to Dendrite Formation in Lithium Anode Based Batteries
Authors: Jampani Hanumantha Prashanth , Gattu Bharat , Murugavel Shanthi Pavithra , Datta Moni Kanchan , Kumta Prashant N
Published: February 2020

Dendrite formation, resulting in gradual capacity loss culminating in cell shorting and failure is the primary problem preventing large-scale utilization of lithium anodes in lithium-anode based batteries (LABs) (1). The use of lithium metal anodes (LMA) for battery applications is largely hindered by the massive volumetric change and inhomogeneous nucleation associated with lithium plating/deplating. Dendrite formation in lithium is a major stumbling block halting the progress of high energy battery systems such as lithium-sulfur and lithium-air batteries.

In this work, a unique approach is used to address both dendritic growth and volumetric changes associated with plating/deplating of large volumes of lithium. Using a Li-rich structurally isomorphous alloys (SIA) with alloying elements specifically forming isomorphous alloy states capable of undergoing lithiation/delithiation without loss in phase and/or crystallographic structure is shown to have stable dendrite-free cycling (Figure 1) for over 200 cycles with capacities of >15 mAh/cm2 (~1627 mAh/g). This presentation will outline this highly efficient method of storing and removing lithium with no dendritic growth demonstrating its promise for opening new frontiers in high power lithium-anode based battery research.

Figure caption:

Figure 1: SEM images of the morphology of (a) lithium electrode and (b) Li-SIA electrode cycled at a current density~100 mA/g (125 cycles) (c) Li-SIA electrode cycled at current density~100mA/g (125 cycles). A clear absence of dendritic structures is observed in the Li-SIA electrode.

References

1. J. Steiger, Mechanisms of Dendrite Growth in Lithium Metal Batteries, in, Karlsruhe, Karlsruher Institut für Technologie (KIT), Diss., 2015 (2015).

Figure 1
Evaluation of Silicon Alloy Contribution in Blended Lithium-Ion Battery Anode with Graphite
Authors: Cao Lei , Yang Chuanbo , Santhanagopalan Shriram , Inman Kristopher , Pesaran Ahmad
Published: February 2020

Contribution of silicon alloy and graphite in blended lithium-ion battery anode were demonstrated and discussed through electrochemical characterization and modeling. Pure and composite materials with varied ratio were evaluated with galvanostatic intermittent titration technique (GITT) and rate tests during delithiation process, followed by model analysis. The large difference between open circuit potential (OCP) of the two material suggested participation of silicon alloy was in later stage of delithiation under slow c-rate condition. A greater diffusion overpotential was also introduced as diffusion coefficients of silicon alloy was smaller by one to two orders of magnitude than that of graphite. Thus, contribution of silicon alloy with greater specific capacity was limited by both higher OCP and slower diffusion kinetics, in agreement of exchange current density obtained from Multi-Scale Multi-Dimensional modeling.
Rapid Sulfur-Melt Infiltration into Electrospun Carbon Nanofibers As Cathodes for Room Temperature Na-S Batteries
Authors: Singh Arvinder , Dillard Caitlin , Kalra Vibha
Published: February 2020

Room temperature sodium–sulfur (RT Na–S) batteries are gaining attention as an alternative to lithium batteries due to natural abundance and relatively low cost of sodium. Although the cell chemistry of RT Na-S batteries is similar to that of Li-S batteries, Na-based batteries are more challenging due to the larger Na+ ions that results in greater volume expansion and slower kinetics during the charge-discharge processes. This, in turn, leads to shorter cycle life, lower power density and lower sulfur utilization compared to Li-based batteries. Notable progress has been made in the last few years to overcome the aforesaid issues by utilizing various carbon hosts for sulfur such as the multiwall carbon nanotubes, hollow carbon, carbon nanofibers and microporous carbon. However, the powder-based carbon/sulfur (insulating) materials are blended together with binders and conducting additives into a slurry with little control on morphology, which ultimately results in discontinuity in the electron transporting network and low sulfur loading in the final cathodes.

Here, we report a novel approach to develop carbon nanofibers (CNFs)/sulfur cathodes using a rapid sulfur melt-diffusion process (~5 seconds). Rapid impregnation of sulfur into free-standing carbon mats eliminates the use of additional components (binders, current collectors and conducting additives) and other time consuming infiltration processes. It is important to mention that rapid melt infiltration approach used here allows precise control of any sulfur loading regardless of the host matrix and can be used for developing high performance sulfur cathodes. Carbon nanofibers (CNFs) used in the present work are produced by electrospinning polyacrylonitrile/dimethylformamide gel and subsequently carbonizing at 1000°C. CR2032 coin cells were assembled using Na metal as anode, 30µL electrolyte (1.5M NaClO4 and 0.3M NaNO3 in tetraethylene glycol dimethyl ether) and as-prepared free-standing CNFs/sulfur cathodes with ~50 wt% (~0.85 mg/cm2) sulfur loading. These cells were cycled at C/5 rate (1C = 1675 mAh g-1) after conditioning 1st cycle at C/10 rate. The initial discharge capacity was ~231 mAh g-1 at C/5 rate, which reduced to ~137 mAh g-1after 20 cycles. The obtained results are comparable to those reported earlier for room temperature Na-S batteries. Electrochemical performance evaluation of CNFs/sulfur cathodes with higher sulfur loading is under investigation.

Figure 1
Investigation of Initial Capacity Loss in Li-Ion Full Cells with Blended Siox/Graphite Anodes
Authors: Faulkner Ankita , Allen Chris , Sa Qina , Bullen Dennis , Beise Ethan , Turteltaub Joanna , Chamberlain Rick
Published: February 2020

SiOx based materials are top anode candidates for next generation high energy cells. Incremental gains in specific capacity, enabled by blending small percentages (<10%) of SiOx with graphite, may be sufficient to meet next gen performance and cost targets. To date, significant progress in cycle life performance of SiOx materials has been demonstrated. In some cases, the cycle life performance exceeds 80% retained capacity to 500 cycles using aerial anode capacities of 4.0mAh/cm2 or greater. However, a common concern related to SiOx based anode materials is the initial capacity loss (Figure 1). Here, the capacity loss behavior occurs with two distinct slopes. Initially, a rapid loss of 10% occurs before 75 cycles. The rapid initial loss is followed by a stable, linear capacity loss slope that mirrors loss in cells without SiOx. At low percentages of SiOx, it is accepted that the dominant failure mechanisms in full cells are SEI growth at the anode and consumption of Li-ions from the system. Consequently, depletion of Li-ions also causes further degradation at the cathode. In this work, we investigate the impact of SEI growth and Li-ion consumption on initial capacity loss. Using a highly robust 3-electrode cell, we monitor the cycling and impedance behavior of the anode and cathode during initial and extended full cell cycling. Three-electrode cell data is coupled with data from half-cell testing, X-ray diffraction, and SEM/EDS to fully understand “cross-talk” between anode and cathode, degradation, and the shift in cell balancing. Additionally, to aid in cell design, we discuss variables such as the percentage of silicon in the anode (5-20%) and the initial anode to cathode capacity ratio (AC ratio). Ultimately, we aim to mitigate this initial capacity loss and further improve cycle life performance.

Figure 1
Dependences of Discharge Capacity, Retention of Discharge Capacity, Average Discharge Voltage and Energy Density, and Rate Capability on the Composition of XLi2MnO3-YLiNi1/2Mn1/2O2-(1-x-y)LiNi1/3Co1/3Mn1/3O2 Li-Rich Solid-Solution Cathode Materials for Li-Ion Battery (II)
Authors: Matsumoto Futoshi , Tamura Naoki , Tsuda Takashi , Gunji Takao , Tanabe Toyokazu , Kaneko Shingo , Ohsaka Takeo
Published: February 2020

A great deal attention has recently been focused on the Li-rich solid-solution layered oxide cathode material Li2MnO3-LiMO2 (LLO, M = Co, Ni, etc.), which exhibits a discharge capacity of more than 200 mAhg-1 when operated above 4.6 V for lithium ion battery. In this study, in order to find the optimal composition of the LLO exhibiting high cathode performance, which are composed of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 (or LiCoO2, LiNiO2) and LiNi0.5Mn0.5O2, the selected 120 samples having different composition were synthesized under identical preparation conditions and the dependence of the performance of the cathode material on the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 (or LiCoO2, LiNiO2) and LiNi0.5Mn0.5O2 in the LLO samples was examined under same experimental conditions in the viewpoint of discharge capacity, retention of discharge capacity, average discharge voltage, energy density and rate capability. In each viewpoint, using ternary phase diagrams, the dependence of each property on the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2 in the LLO samples was evaluated. Based on the results obtained, it was comprehensively concluded that Li[Ni0.208Li0.183Co0.033Mn0.575]O2 (55% Li2MnO3-35% LiNi1/2Mn1/2O2-10% LiNi1/3Co1/3Mn1/3O2) possesses the best composition as cathode material for LIBs among the testes 120 samples. In addition, the synthesis condition of Li[Ni0.208Li0.183Co0.033Mn0.575]O2 was examined more in the viewpoint of annealing temperature.
Using X-Ray Diffraction and Imaging for the Investigation of Battery Materials: From Bulk Structural Characterization to in Situ and in Operando Measurements
Authors: Masiello Fabio , Nenert Gwilherm , Speakman Scott , Quinn Julie , Sommariva Marco , Gateshki Milen
Published: February 2020

X-ray diffraction and scattering are powerful tools for the study of battery materials.

We describe here X-ray methods which allows the researcher to combine multiple X-ray techniques to obtain a wealth of information about new materials used in battery applications.

By using X-ray diffraction it is possible to identify the different crystallographic phases and quantify the amount of each phase in the bulk material. Moreover, with the Rietveld method it is possible to refine the crystallographic structures of the different materials.

It is also possible to study the battery in situ and in operando. This can be done either in reflection geometry or in transmission geometry. In order to perform the measurement in transmission geometry, more penetrating radiation is required, e.g. Mo or Ag radiation. A newly developed X-ray detector allows for shorter measurement time and/or better quality data thanks to the higher efficiency of the CdTe sensor material.
Dynamic, Reversible Oxygen Redox As a Mediator of Voltage Hysteresis in Lithium-Rich Layered Oxide Electrodes
Authors: Gent William , Lim Kipil , Hong Jihyun , Liang Yufeng , McIntire Mitchell , Shapiro David , Kilcoyne David , Mehta Apurva , Ermon Stefano , Vine David , Yang Wanli , Prendergast David , Toney Michael F , Chueh William C
Published: February 2020

Anionic redox activity has recently been shown to be an important process that governs the electrochemical behavior of lithium-rich layered oxide electrodes. In 3d transition metal (TM) systems, it is typically believed that during the first charge this redox activity occurs via reversible depopulation of localized O2p electronic states. However, the electrochemistry of lithium-rich layered oxides with 3d TMs changes drastically after the first charge, suggesting that the redox mechanisms likely change. In this work, we investigate the nature of this change and reveal the crucial role of oxygen redox in mediating the unusual electrochemistry in these materials. By coupling a variety of structural probes with Scanning Transmission X-ray Microscopy (STXM) throughout the entire cycle life of a Li- and Mn- rich Ni/Mn/Co layered oxide (LMR-NMC), we correlate spatially localized transmission X-ray Absorption Spectra (XAS) at the TM L edges and O K edge with the evolving LMR-NMC atomic structure. Through our results we develop a unifying picture of how the structure-redox processes in LMR-NMC evolve as the material degrades, considering anion redox, transition metal migration, oxygen evolution, and vacancy formation. Specifically, we find that anion redox plays a crucial role in both the charge/discharge hysteresis during all cycles as well as the fading voltage over extended cycling. Our results paint a holistic picture of the electrochemical mechanism of LMR-NMC, linking understanding of the structural evolution, redox mechanisms, and electrochemical behaviors.