bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion Processes in Lithium-Sulphur Cells. Isothermal Calorimetry As Method of Their Identification
Authors: Kuzmina Elena , Kolosnitsyn Vladimir , Mochalov Sergey , Karaseva Elena , Nurgaliev Azat
Published: February 2020

Electrochemical system of Lithium-Sulphur is very promising because of its high theoretical specific energy (2600 Wh kg-1). In addition to sulphur is cheap and available.

However the laboratory prototypes of lithium-sulphur batteries (cells) have several significant disadvantages: low practical specific energy (250-300 Wh kg-1at first cycles), high rates of self-discharge (>3% per month) and capacity fade (>0.1% per cycle) during prolong cycling.

The main reason of low practical specific energy of lithium-sulphur cells is the large shares of ballast components including greater share of an electrolyte than in lithium-ion cells.

Corrosion processes at lithium electrodes cause the high rates of self-discharge and capacity fade. It is related to the solubility of sulphur and lithium polysulphides in the electrolyte systems and their direct chemical interactions with the lithium electrodes.

S8 + 4Li -> Li2Sn + Li2Sk, k+n=8; k & n ≥ 1                                                   (1)

Li2Sn + 2Li -> Li2Sm+Li2Sk; k+m=n, k & m ≥ 1                                             (2)

Traditionally the effect of different factors on the corrosion processes in lithium-sulphur cells is measured by results of prolong charge/discharge cycling: the values of charge and discharge capacities and rate of their fading during cycling. Such studies are slow because corrosion process occurs slow at the initial cycles and does not affect the results so it is hard to measure the efficiency of suggested methods to suppressed the corrosions processes.  

As results show the combine method of isothermal calorimetry and galvanostatic polarisation (cycling) is very informative and convenient method to study corrosion processes in chemical power sources. This method allows us to identify corrosion processes at the initial stages of cycling and estimate their intensity. 

The aim of this work is to estimate the corrosion activity of sulphur, lithium polysulphides and factors, affecting their interactions with metallic lithium, by isothermal calorimetry combined with galvanostatic polarisation.

The reported study was partially supported by RFBR, research project No 14-03-31399.
Nax(Fe,Mn)O2 Layered Oxides Used in Sodium Batteries : Structural Transformations Induced By the Electrochemical Process
Authors: Guignard Marie , Mortemard Benoit , Carlier Dany , Wattiaux Alain , Delmas Claude
Published: February 2020

Layered sodium oxides with the formula NaxMO2 (where x is comprised between 0 and 1, M is a transition metal) have been intensively studied these last thirty years either for their unique physical properties (high thermoelectric power, superconductivity …) or with a view for their use in large sodium-ion batteries. More recently, advanced electrochemical properties of some NaxMO2 systems containing only one transition metal have been re-investigated and new complex materials with several transition metals in the MO2 layers have been synthesized and studied. In particular, systems containing non-toxic and abundant elements such as manganese and iron appear very attractive and first results in the P2-NaxMn1/2Fe1/2O2 system have showed a capacity as high as 190 mAh/g [1]. Other promising results were obtained in other compositions in manganese- and iron-based systems [2,3].

In this context, we recently studied some NaxMO2 phases used as positive electrode in Na cells with a special focus on the structural transformations and redox processes occurring during cycling in P2- and O3-Nax(Fe,Mn)O2 systems. The structures of all starting materials were determined by Rietveld refinement from powder X-Ray diffraction data. The electrochemical study was carried out in sodium batteries with a solution of NaPF6 in PC as electrolyte. For all materials, a very good reversibility of the electrochemical process was observed. In situ and ex situ X-ray powder diffraction experiments were carried out to understand better the structural transformations induced by the electrochemical (de)intercalation process. In parallel, redox processes were studied by ex situ and in situ Mössbauer spectroscopy.

[1] N. Yabuuchi, M. Kajiyama, J. Iwatate, H. Nishikawa, S. Hitomi, R. Okuyama, R. Usui, Y. Yamada, S. Komaba Nature Materials, 2012, 11, 512.

[2] J. Zhao, J. Xu, D. H. Lee, N. Dimov, Y. S. Meng, S. Okada J. Power Sources, 2014, 264, 235.

[3] D. Yuan, X. Hu, J. Qian, F. Pei, F. Wu, R. Mao, X. Ai, H. Yang, Y. Cao Electrochimica Acta, 2014, 116, 300.
Mechanistic Insights into Rechargeability and Capacity Limitations in Nonaqueous Li-O2 Batteries
Authors: McCloskey Bryan D
Published: February 2020

Multiple directions in battery research are now being pursued in hopes of advancing beyond the specific energy limits imposed by conventional Li-ion electrode materials.  For example, ‘beyond Li-ion’ battery chemistries, such as Li-O2, Li-S, and Mg-ion, are currently being explored as potential successors to Li-ion batteries given their very high theoretical specific energies; yet severe technical challenges have prohibited them from becoming a practical reality.  The objective of this presentation is to provide an assessment of such challenges, in particular, instabilities of the electrolyte and cathode, and Li2O2 electronic conductivity limitations, facing the nonaqueous Li-O2 battery cathode. Results will be presented on the characterization of the Li2O2 formation mechanism and how the mechanism could be engineered to potentially alleviate problems associated with Li2O2 deposition on the cathode.
P2 Structure Sodium Manganese Oxides for Na-Ion Batteries
Authors: Billaud Juliette Marie , Singh Gurpreet , Armstrong Anthony Robert , Gonzalo Elena Candida , Roddatis Vladimir , Armand Michel , Somerville James William , Maitra Urmimala , Tapia-Ruiz Nuria , Rojo Teófilo , Bruce Peter G
Published: February 2020

Lithium ion batteries have dominated the world of portable electronic devices over the past two decades and are making their way into the electric vehicle market due to their high energy density. However, recently sodium ion batteries have regained the interest of the scientific community due to the high and uniform abundance of sodium across the world and consequent low cost compared to lithium, making them attractive for grid storage. Various electrode materials have been studied for sodium ion batteries. Layered oxides, NaMO2, where M is one or more transition metals, represent an attractive class of cathodes for Na batteries. Here we show that Na0.67MnO2 with the P2 structure, Figure 1 a), exhibits a high capacity (175 mAhg-1), close to the best reported for a Na cathode, and with good capacity retention, in contrast to previous studies of Na0.67MnO2 where the capacity faded rapidly. [1] Due to the presence of Jahn–Teller active Mn3+ in Na0.67MnO2, the structure undergoes various structural transitions during sodiation/desodiation leading to many voltage steps in the charge/discharge profile. [2], [3] We have investigated reducing the phase transitions by substituting Mn3+ ions with electrochemically inactive dopant ions, which have a strong preference for octahedral sites in the layered oxide framework. This leads to the formation of a highly stable framework that shows a smooth charge/discharge profile with very low polarization even for a substitution level as low as 5%, Figure 1 b) and a capacity of ~ 175 mAhg-1. Such an observation is significant for the future development of sodium ion battery cathode materials.

References:

[1]         A. Caballero, L. Hernán, J. Morales, L. Sánchez, J. Santos Peña, and M. A. G. Aranda, J. Mater. Chem., 12, 1142–1147.

[2]         N. Yabuuchi, M. Kajiyama, J. Iwatate, H. Nishikawa, S. Hitomi, R. Okuyama, R. Usui, Y. Yamada, and S. Komaba, Nat. Mater., 11, 512-517.

[3]           X. Wang, M. Tamaru, M. Okubo, and A. Yamada, J. Phys. Chem. C, 2013, 117, 15545.

Figure 1
Substituted Garnet Materials for Safer Lithium Ion Batteries: Composition Optimisation and Full Cell Application
Authors: Buannic Lucienne , Manalastas William Wang , Aguesse Frédéric , Han Man Huon , López del Amo Juan Miguel , Singh Gurpreet , Llordés Anna , Kilner John A.
Published: February 2020

Solid state lithium ion conductors have been identified as very promising candidates for the replacement of liquid organic electrolytes [1]. Not only will they provide a physical barrier to Li dendrite growth but they will also obviate the use of flammable and toxic solvents. Amongst the ceramic candidates, Li7La3Zr2O12 in its cubic phase has been reported as one of the fastest lithium ion conductors (σLi+ = 0.4 mS.cm-1at 25ºC) [2]; however the stabilization of this material in the cubic phase requires high processing temperatures and long sintering times.

Our work has been dedicated to identifying suitable substitution strategies in order to stabilize the cubic phase at lower temperature while maintaining a high density for the material. In addition to studying the effect of Al substitution on the Li site, we have explored the benefits of partially replacing Li+ by Ga3+. The substitution of Li+ by a cation with higher oxidation state decreases the number of charge carriers (Li+) in the structure and could be detrimental to the conductivity of the material. Nevertheless, the preferential location of Ga3+ on the Li tetrahedral sites forces Li+ onto the distorted octahedral sites, thereby increasing the disorder on the Li sites and stabilizing the cubic phase of the garnet. This substitution leads to a considerable gain in conductivity, with values as high as 1.3 mS.cm-1 for Li6.55Ga0.150La3Zr2O12 at 25ºC [3]. Alternative substitutions on the Zr4+site will also be discussed, leading to a wider range of compositional possibilities.

In order to demonstrate the applicability of the garnet electrolytes to commercial systems, the implementation of these substituted garnets in full cell Li-ion batteries will also be reported.

[1] Knauth P. Solid State Ionics, 10, 911 (2009)

[2] Murugan, R.; Thangadurai, V.; Weppner, W. Angewandte Chemie International Edition, 46, 7778 (2007)

[3] Bernuy-Lopez, C.; Manalastas, Jr. W.; Lopez del Amo, J-M.; Aguadero, A.; Aguesse, F.; Kilner, J. A. Chemistry of Materials, 26, 3610 (2014)

Figure Caption:

(a) Crystal structure of garnet Li7-3xGax□2xLa3Zr2O12 where La (dodecahedral), Zr (octahedral) and O atoms are represented by dark red, blue, and red circles respectively. Li (octahedral), Li (tetrahedral), and Ga (tetrahedral) are represented in grey, turquoise blue, and green respectively. (b) Enlarged area of the Li vacancy highlighted in (a) showing the Li+ pathways. (c) Arrhenius plot of Li6.55Ga0.150La3Zr2O12between 340 and 180 K.

Figure 1
All Solid State Li-Ion Batteries Based on Cubic Garnets: From Material Optimization to Thin Film Battery Design
Authors: Rupp Jennifer L. M. , Ayfon Semih , Garbayo Inigo , Pfenninger Reto , Rawlence Michael , Struzik Michal
Published: February 2020

The next generation of energy storage devices relies on a broad and adaptable range of volumetric and gravimetric energies to compete with the challenges in stationary, mobility and portable electronic electricity supply. Here, all solid state batteries based on Li-garnet-based structures are interesting model systems as these allow for complete solid state battery types that: i.) can partially use industrial waste heat to increase charging times (increased Li+ diffusion) for stationary, ii.) with 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 on chip.

Firstly, we report on Al:Li7-2xLa3Zr2O12 bulk pellet and thin film processing, their crystallization and ionic transport characteristics. Secondly, from a materials processing perspective we report on a new modified sol-gel synthesis-combustion method to lower the nano-particle production of the solids to ~ 600°C. Here, we exemplify stable electrolyte compounds based on Li7-3x(Gax)La3Zr2O12. Thirdly, for N-site doping Li7-xLa3Zr2-xTexO12 with x = 0.25 to 0.35 were prepared by synthesis in solid state, and Te is studied as alternative to Ga and Al stabilizers as battery electrolyte without grain boundary stabilization.

Finally, we concluded on the suitability of these new materials for scaling down to thin film microstructures, as potential Li-garnet electrolytes in all solid state batteries for portable electronic applications. First strategies on how to design optimum thin film-microbatteries adaptable to chemo-mechanical variations during operation will be shown. Here, two different model designs are described: (i.) the fabrication of microbattery dot arrays and (ii.) wrapped anode/electrolyte/cathode microstructures with tunable strain.
Radiation-Grafted Anion-Exchange Polymer Electrolytes for Clean Energy Applications
Authors: Ponce Gonzalez Julia , Willson Terry , Poynton Simon , Murphy Sam , Slade Robert CT , Whelligan Daniel , Hamerton Ian , Varcoe John
Published: February 2020

Anion-exchange polymer electrolyte materials are being developed and studied for an increasing diversity of clean energy technologies, such as alkaline polymer electrolyte fuel cells, redox flow batteries, biological fuel cells, and reverse electrodialysis cells. These technologies include the application of the anion-exchange polymer electrolytes in conditions that span the pH range from highly acidic, through more neutral environments, and finally to highly alkaline.

This presentation will highlight the versatility of the radiation-grafting methodology in that it allows the production of polymer electrolytes containing numerous different morphologies and chemistries, including both cation-exchange and anion-exchange types. Once initial (small scale) experiments have been conducted and synthesis protocols have been developed, this methodology has the advantage that reasonably large (for lab-scale) quantities of materials can be synthesised, e.g. 10 – 100s of grams and several m2 sized batches, with excellent repeatabilities; this also allows for a large number of tests and experiments to be conducted on the same batch of material. This synthesis platform therefore facilitates research into such materials including research that compares ion-exchange materials where a single variable has varied: e.g. anion-exchange polymer electrolyte materials with the same ion-exchange capacities and polymer backbones but where the chemistries of the cationic head-groups is varied, anion-exchange polymer electrolyte materials with the same ion-exchange capacities and cationic head-groups but where the polymer backbones are varied, or anion-exchange polymer electrolyte materials with the same polymer backbone and head-group chemistries but where the ion-exchange capacity is varied.

The materials to be discussed include radiation-grafted anion-exchange membranes (with similar ion-exchange capacities) that possess an array of cationic head-group chemistries, including the benchmark benzyltrimethylammonium, benzyltriethylammonium, benzylimidazoliums, benzylpyridiniums, benzylpiperidiniums, and benzylmorpholinium. Some of these anion-exchange polymer electrolytes have reasonable stabilities at alkaline pHs (e.g. for use in alkaline polymer electrolytes fuel cells), whilst others can only be applied to systems where the pHs, that the materials are exposed to, are more neutral (e.g. materials for use in reverse electrodialysis cells). The ionic conductivities of these materials appear to be high enough for use in the above mentioned technologies.

As a small aside, it will also be demonstrated that cation-exchange membranes with different chemistries can also be synthesised and this is of interest to applications such as the more well-known proton-exchange membrane fuel cells as well as reverese electrodialysis.

Figure 1
Regeneration of Activated Carbon Using Electric Potential for Upgrading Bio-Gas to Bio-Methane
Authors: Farooq Muhammad , Andresen John
Published: February 2020

The anaerobic digestion (AD) industry in the UK has experienced rapid growth in recent years over 130 operational AD plants in the UK outside the sewage treatment sector and more than 340 further projects are under development. Thus, there is an increasing demand for upgraded biogas to be used as vehicle fuel or injected to the natural gas grid. Since a typical biogas contains 1000 - 10,000 ppm hydrogen sulphide, its removal below 5ppm is required for uses beyond combined heat and power (CHP). Although a number of established methods exist for removal of hydrogen sulphide they tend to be costly. A common industry practice is to adsorb hydrogen sulphide using a granular activated carbon (GAC) bed which is subsequently disposed as hazard waste. Accordingly, this research is focused on regeneration of activated carbon using an electric potential.  Fine diameter MI construction thermocouples are used for this purpose. Thermocouples are terminated with a miniature plug. The driving force is a high capacity system that is regenerative, inexpensive and leaves no waste. Initially, 1% hydrogen sulphide / 99% nitrogen gas mixture is used as a benchmarked against an industrial activated carbon specifically used for hydrogen sulphide removal. Several Electric Conductive Activated Carbons (ECAC) will then be reported for their adsorption/ desorption potential. It is envisioned that this method can transform the production of bio-methane where early estimates have calculated that a regenerative system could save up to 50% of running costs.

Key Words:
 Biogas, Electric conductive activated carbons, Thermocouples.
Polysulphide Air Redox Flow Battery - a Novel Solution for Grid Scale Energy Storage
Authors: Xia Yuhua , Yufit Vladimir , Brandon Nigel P.
Published: February 2020

The widespread deployment of flow batteries, an important part of energy storage technologies, has been largely restricted by its high cost. A novel, recently patented redox flow system utilising polysulphide redox and oxygen reduction/evolution reactions offers a cost effective solution for electricity storage and delivery.

The schematic operation of polysulphide-air flow battery is illustrated in the Figure below. The polysulphide anolyte is pumped through the porous media at the anode compartment when the reversible electrochemical redox reaction of soluble polysulphide/sulphur occurring. Concurrently the oxygen reduction/evolution occurs at catalytically active gas diffusion media at the cathode compartment. Experimental testing of polysulphide-air system was carried out in 5 cm2 active area single cell setup connected to peristaltic and air pumps. The stable open circuit voltage of 0.68 V was achieved in 0.5 Na2S/ 0.5 M S/ x 1M NaOH solution. This OCV was slightly lower than the theoretical value of 0.85V likely due to crossover of anolyte species and bad contact of circut. A maximum power density of 2.1 mW/cm2 was achieved during the discharge. To decouple anode and cathode processes half-cell measurements including electrochemical impedance spectroscopy were performed. The collected data clearly indicate that the major losses happened on polysulphide side. Increased flow rate of polysulphide anolyte just slightly improved the performance. This work will present novel data with improved catalytic activity of polysulphide side and increased performance of the polysulphide-air system.

Figure 1
Challenges and Progress in Membranes, Catalysts, and Meas for PEM Water Electrolysis
Authors: van Dijk Nicholas , Payne Johnson Elisabeth , Dodwell James , Lister Rachel , Platt Laura , Brightman Edward , Hinds Gareth
Published: February 2020

In a world in which fossil fuel energy is becoming ever more scarce and expensive and countries are struggling to meet their carbon reduction obligations, hydrogen solutions have finally reached the top of energy agendas. The only industrially applicable zero carbon method to produce hydrogen is via electrolysis utilizing renewable sources of electricity.

ITM Power is at the very heart of the initiatives and programmes to adopt hydrogen technology that will reduce both carbon footprints and energy costs. Using its technology and knowhow, ITM is aiming to be the world leading supplier of both infrastructure for the production of green hydrogen transport fuel, and products for the generation and storage of hydrogen fuel from internittent renewable energy sources.

Despite having a number of electrolyser products on the market, ITM Power have an active PEM electrolyser research and development programme aimed at the next generation of electrolysers. Some of the electrochemical and materials challenges faced by both ITM and the industry will be presented along with recent results, examples given below.

PEM electrolysers have a lifetime of 5-10 years; as such there is difficulty in getting new materials to market. ITM along with the National Physical Laboratory have used a novel in-situ reference electrode to help understand catalyst degradation within the cell. This approach enables separation of the relative contributions of anode and cathode to the overall reaction. During shut down periods it was observed for the first time that the cathode contributes more to changes in the open circuit voltage. This knowledge has been used to show that the majority of the degradation is occurring on the cathode catalyst, which is in contrast to the perceived thought which assumes the anode degrades faster. Changes in the electrochemically active surface area of the platinum cathode as a result of potential cycling were determined in-situ via hydrogen underpotential cyclic voltammetry. Scanning electron microscopy and X-ray tomography were used to correlate changes in catalyst morphology with performance degradation of both carbon-supported and unsupported platinum catalysts. These experiments have led to the development of accelerated stress tests, based on cycling of the electrode potential, for PEM electrolyser catalysts.

In addition ITM have made progress in the development of new membranes for PEM electrolysis. ITM’s approach to membrane development is the UV polymerisation of low cost hydrocarbon monomers. A new highly conductive membrane has been developed and tested to 3 A∙cm-2. This membrane is 125 um thick to minimise hydrogen crossover, has a conductivity of 260 mS∙cm-1 and is extremely low cost. When made into a MEA, this membrane allows a voltage of below 1.6 V at 1 A∙cm-2 at only 55°C. This has been benchmarked against Nafion(R)115.
New Progress in Ruthenium Based Oxygen Reduction Catalysis
Authors: Schechter Alex , Teller Hanan , Krichevski Olga
Published: February 2020

Platinum-based catalyst, the stat- of- the-art in oxygen reduction catalysis in PEMFC is also one major factor, impeding the commercialization of this energy conversion technology. This is mostly due to high Pt cost and insufficient durability during prolong FC operation time. Recently, there is a growing interest in Pt free oxygen reduction reaction (ORR) catalysis for acidic fuel cells.  Ruthenium chalcogenide catalysts have been reported to present highly stability and fair activity in acid environment [1,2].

In this study, ruthenium selenide, phosphide and ternary RuCoSe were synthesized using various methods, following by a rigorous study of their activity, as oxygen reduction catalysts in acid solutions.  

The synthesis of selenide-based nano size particles was carried out in a rather straightforward manner, using microwave assisted polyol and sodium borohydride reduction method and inorganic RuCl3, CoCl3 and Se or H2SeO3. However, the preparation of RuP and Ru2P has been found to be much more challenging. These methods include reaction at high temperature in closed vessel under autogenic pressure.

ORR study on ruthenium-based catalysts in 0.5M sulfuric acid solution was studied using rotating disk ring electrode RRDE method coupled by surface and bulk and Raman, XPS and EDS and XRD spectroscopic methods coupled with SEM and TEM microscopy. We have found that there are more than single active sights. The number of these sights is controlled by the bulk and surface composition as well as surface oxides formed on the particles at high potentials. Interestingly, most of the O2 reduction proceed directly to water via 4e- reduction process.  Calculated rate consents suggest that reduction by 2e to H2O2plays a major role at high potential, whereas at low potentials the reaction proceed by direct reduction of 4e-.

Extremely high selectivity in the presence of methanol was measured (methanol tolerance) was found in Ru2Se (figure 1).

Figure 1.
Oxygen reduction on Ru2Se and Pt in the presence of methanol

(electrode polarized to 0.4 V)

[1] I. V. Malakhov, S. G. Nikitenko, E. R. Savinova, D. I. Kochubey, and N. Alonso-Vante, J. Phys. Chem. B 2002, 106, 1670-1676

[2] Georgios A. Tritsaris, Jens K. Nørskova, Jan Rossmeisla, Electrochimica Acta 56 (2011) 9783– 9788

Figure 1
Understanding Ionomer in Fuel-Cell Catalyst Layers
Authors: Weber Adam Z , Kusoglu Ahmet , Tesfaye Meron
Published: February 2020

One of the keys to optimizing polymer-electrolyte-fuel-cell performance is understanding it’s transport phenomena. This is especially critical in the polymer electrolyte in both the bulk and in particular the catalyst layers, where it exists as thin, nanometer-thick film covering the catalyst agglomerates. In these structures, it is known to perhaps inhibit performance, especially as the total platinum content is reduced. Interactions of the membrane with the local environment and as a thin film within the CL result in highly complex material behavior that is highly dependent on the environmental conditions, ionomer thickness, and the material interactions, e.g., carbon, platinum, etc. Thus, characterization of the role of ionomer in fuel-cell catalyst layers requires understanding the transport properties and water-uptake behavior throughout a wide thickness range.

In this talk, the role of the ionomer and its underlying structure/function relationships will be elucidated. Ex-situ testing of the catalyst-layer ionomer demonstrates reduced water content for both Nafion and the short-side-chain, lower equivalent weight 3M ionomer. These studies are complemented by thin-film structural and swelling measurements using x-ray scattering and ellipsometry, respectively, which likewise show reduced water content and phase separation as the film thickness decreases. This decrease is caused by an increase in the packing of the polymer chains resulting in increases in mechanical modulus. In addition, direct measurement of the permeability of thin-films is accomplished, again showing that the thin films may result in substantial mass transport limitations.

Acknowledgement

The authors thank Steve Hamrock and Mike Yandrasits from 3M for helpful discussion and ionomer samples as well as Kunal Karan, Kirt Page, Chris Stafford, and Mike Hickner for discussions. This work made use of facilities at the Advanced Light Source (ALS), supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy. This work was funded by the Assistant Secretary for Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, of the U. S. Department of Energy under contract number DE-AC02—05CH11231 and a CRADA with Toyota Motor Company.
Nitrogen-Doped Graphene Foam As a Metal-Free Electrocatalyst
Authors: Lyth Stephen Matthew , Liu Jianfeng , Sasaki Kazunari
Published: February 2020

Pt nanoparticles are generally used as the electrocatalyst in proton exchange membrane fuel cells (PEMFCs). However Pt is expensive, and has limited durability due to agglomeration, dissolution, and carbon corrosion in the harsh environment of the fuel cell cathode. Alternative electrocatalysts have been proposed; one of the most popular being Fe/N/C-based electrocatalysts. However, these non-platinum group metal (non-PGM) electrocatalysts struggle to compete with platinum in terms of performance and durability in the acid environment of a PEMFC.

In alkaline media, the oxygen reduction reaction (ORR) kinetics are much faster, and this means that non-PGM electrocatalysts can compete with Pt. Until recently, anion exchange membrane fuel cells (AEMFCs) were not considered to be able to compete with PEMFCs. However, recent advances in membrane technology have made them more viable.

Here, we show that even a completely metal-free nitrogen-doped carbon can have electrochemical ORR activity comparable to that of platinum. Moreover, we perform electrochemical load-cycle durability tests and show that even after 60,000 potential cycles negligible degradation is observed for this electrocatalyst system in alkaline. In contrast, the performance of Pt is much worse after the same test. In conclusion, non-precious nitrogen-doped graphene foam is a potential electrocatalyst for the oxygen reduction reaction in alkaline anion exchange membrane fuel cells.
New Non-PGM Catalyst Synthesized By Wet Ball Milling for Fuel Cell Systems
Authors: Zhuang Shiqiang , Nunna Bharathbabu , Lei Lin , Lee Eon Soo
Published: February 2020

Non-platinum group metal (non-PGM) catalysts have a huge potential in many electrochemical systems such as fuel cells due to the high raw material cost of PGM catalyst. However, there is a significant gap between the current level of electrochemical performance of non-PGM catalysts and that of PGM catalysts. Nitrogen doped-Graphene/MOF (N-G/MOF), a new high performance non-PGM catalyst which was synthesized by high energy wet ball milling with graphene oxide, melamine, and Metal organic framework material as raw materials, was investigated in this research. The physical, chemical, structural and electrochemical properties of new synthesized N-G/MOF catalysts were characterized by XPS, FTIR, SEM-EDS, TEM, XRD, RRDE and fuel cell testing station. The comparison between properties of N-G/MOF, N-G (without MOF), and MOF (without N-G) shows that N-G/MOF has better electrochemical performance than both N-G and MOF. Furthermore, the catalytic mechanism of N-G/MOF catalysts was investigated in this research. The successful accomplishment of the new MOF-based catalytic materials and the understanding of the mechanism provide the substantial way to the cost-effective and fuel-efficient energy conversion system.
Phosphate Based Ceramics As Solid Electrolyte for High Temperature Lithium Ion Batteries
Authors: Cui Yuantao , Rohde Magnus , Mahmoud Morsi M , Ziebert Carlos , Seifert Hans Jürgen
Published: February 2020

A Li-ion battery with liquid electrolyte may suffer from security risks such as inflaming or short circuits. A solid electrolyte made of ion conducting glass-ceramic is thermally more stable. If the ion conducting ceramics as combined electrolyte and separator could be used in a battery, the battery will be safer.

LAGP (Li1+x AlxGe2-x (PO4)3) was investigated as a candidate for solid electrolytes in Li ion batteries. LAGP glass samples were produced using the melt-quench-method. Samples were fabricated using powder compaction by sintering or by direct heat treatment of the glass. Their ionic conductivities were measured with impedance spectroscopy. Dilatometer measurements, X-ray diffraction and scanning electron microscope analysis were also carried out. The thermal properties like crystallization temperature, heat capacity and thermal conductivity were measured with differential scanning calorimeter and Laser-Flash apparatus.

Multiple batches of LAGP with different composition were produced. The ionic conductivity of 3·10-4 S/cm at room temperature and 1·10-2 S/cm at 150°C was achieved. The relationship between the process parameters, the microstructure and ionic conductivity of the solid electrolyte was studied. Also, their influence on the heat capacity and the thermal conductivity was studied.

All-solid test cells were fabricated using LAGP ceramic as solid electrolyte. Magnetron sputtering, spark plasma sintering and furnace sintering were used to produce the anode-electrolyte-cathode multilayer tablets. The tablets were assembled in swagelok-cells and tested between 100°C and 200°C.
Study on the Electrochemical Performance of Poly(ethylene ether carbonate) (PEEC)-Based Polymer Electrolyte for All Solid-State Lithium Batteries
Authors: Jung Yun-Chae , Kim Duck-Hyun , Shin Woo-Cheol , Ue Makoto , Kim Dong-Won
Published: February 2020

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices and electric vehicles, due to their high energy density and long cycle life.[1,2] However, safety issues have become a significant concern owing to the use of flammable liquid electrolytes.  In this respect, the development of non-flammable solid electrolytes may provide a fundamental solution to the safety issue of lithium batteries.  Solid polymer electrolytes based on poly(ethylene oxide) (PEO) present advantageous features such as flexibility in the shape of battery design, absence of leakage of organic solvents and better safety than liquid electrolytes.[3] However, they show poor ionic conductivity at ambient temperatures due to their tendency to crystallize. Moreover, their poor mechanical properties at high temperature due to the melting transition may cause short circuits between two electrodes in cases where unusually high heat is generated.  In order to overcome these problems, we prepared polymer electrolytes based on alternating copolymer composed of ethylene oxide and ethylene carbonate (poly(ethylene ether carbonate), PEEC) in the form of flexible thin film, and their electrochemical properties were investigated.  The polymer electrolytes showed higher ionic conductivity and superior electrochemical stability compared to those of PEO-based polymer electrolyte. The polymer electrolytes were applied to the all solid-state lithium batteries, and their electrochemical performance was evaluated.

 References

[1] J. M. Tarascon, and M. Armand, Nature, 414 (2001) 359.

[2] P. G. Bruce, B. Scrosati, and J. M. Tarascon, Angew. Chem. Int. Ed. 47 (2008) 2930.

[3] E. Quartarone, and P. Mustarelli, Chem. Soc. Rev. 40 (2011) 2525.
High Throughput in-Situ Analysis of Gas Evolution in Lithium Ion Batteries
Authors: Clemmons James Owen
Published: February 2020

Gas evolution as a result of electrolyte decomposition during the formation operation and storage of rechargeable lithium ions batteries is a common problem for high performance lithium-ion batteries as cell makers and material suppliers strive to find solutions enabling cells to function at increased voltages in the quest for greater energy.  Outgassing during cell formation requires cell manufactures to degass cells thus leading to increased manufacturing costs.  Gas evolution during the cycling and high temperature storage of cells can lead to potential safety hazards while also contributing to capacity fade and cell deformation especially in pouch cells. Unfortunately, the detection of origin of gas evolution is challenging due to the lack of capability of in-situ gas measurement. Conventional methods such as the Archimedes water-displacement test, allows one gas measurement after cell testing which makes it impossible to track when gas was generated and consumed, while other in-situ techniques are extremely complicated and only allow a few experiments to be run at a time. Wildcat has developed a novel high throughput gas cell architecture which allows for the monitoring of gas in-situ.  

Using high throughput gas cells, a gas measurement is taken every 0.1 seconds throughout any given electrochemical test which allows for the evaluation of gas evolution for hundreds of cells run in parallel.  This allows for Wildcat’s scientists to rapidly evaluate thousands of electrolytes in full cells, while simultaneously evaluate their cycling or storage performance, thus allowing for the dramatic acceleration of electrolyte development.  In addition to the development aspect Wildcat has found this technique often shines the light on the understanding of electrolyte decomposition mechanisms.  By presenting various case studies this presentation hopes to illustrate the power of Wildcat’s high throughput in situ gas cells.
Development of High Energy Cathode Phosphates Via High Throughput Methods
Authors: Yang Johnny , Li Bin
Published: February 2020

Olivine phosphates as cathode material became attractive due to the greater structural stability of (PO4)3- units compared to other counterparts like LiCoO2, LiNixMnyCozO2 and LiMn2O4. Since 1997 Goodenough’s group had introduced LiFePO4 as cathode material, it has been one of the major cathode materials, especially in China EV battery market currently. However, the energy density (578 Wh/kg) is limited due to the low operating potential 3.4 V vs. Li. Development of high energy density (700 Wh/kg) LiMnPO4 cathode material became attractive due to its high operating voltage 4.1 V vs. Li, which falls within the electrochemical stability window of conventional electrolytes.

With Wildcat Discovery Technologies’ high throughput research workflow, we developed a low cost and scalable method for LiMnPO4 with capacity > 150 mAh/g, 1C rate > 95%, and > 90% capacity retention over 500 cycles. This research was systematically studied in precursor selection, doping screen, composition, coating, synthesis conditions and electrolyte formulation screen. Moreover, this technology has been successfully demonstrated in 1Kg per batch synthesis.
Sb-Ag Liquid Alloy Anode for Solid Oxide Fuel Cell with Carbon As Fuel
Authors: Duan Nan-Qi , Cao Yong , Chi Bo , Pu Jian , Li Jian , Tan Yuan
Published: February 2020

Liquid Sb has been accepted for direct carbon solid oxide fuel cell anode material for its unique physical and chemical properties. Sb and Sb2O3 have a relatively low melting point of 630 and 636 °C respectively and the electrochemical formed Sb2O3 would drift away from the Sb/electrolyte interface because of density difference. So the density difference and viscosity of the liquid phases have influence on the two phase convection and the average thickness of insulator Sb2O3 layer. Sb1-x
-Ag
x
(x
= 0.1, 0.2, 0.3) alloy has a lower melting point and higher density than pure Sb. Since Ag2O would not exist stably at temperature higher than 300 °C, Ag atoms in the Sb1-x
Ag
x
anode will not participate to the electrochemical reaction with O2- at intermediate temperature. A tubular 8 mol.% Y2O3 stabilized ZrO2 (YSZ) supported SOFC with La0.6Sr0.4Co0.2Fe0.8O3-Gd0.1Ce0.9O2-δ (LSCF-10GDC) as the cathode and Sb1-x
-Ag
x
as anode was fabricated by slurry-casting, slurry-dipping and sintering processes. The primary I-V/I-P performance of the Sb1-x
-Ag
x
abode cells was much lower than the Sb anode cell. Alloying Ag seemed to have a negative influence on the electrochemical reaction between Sb and O2-, which might due to Ag atoms taking partial Sb atoms positions. Working at a current density from 0.1, 0.2, 0.3, 0.4 to 0.5 A cm-2 at 750 °C, the final I-V/I-P performance of the alloy anodes cells was just a little lower than the Sb anode cell. The EDX analysis and SEM pictures of the tested cells revealed that elements re-distribution happened in the anode. The primary uniform distributed Sb1-x
-Ag
x
alloy appeared to be a layered structure and the Ag content in the button layer was higher than that in the upper layer.

Figure 1
In Situ Transmission FTIR Spectroscopy Investigation of the Electrolyte Oxidation Reaction Under High-Voltage
Authors: Wang Long , Ma Yulin , Qu Yunteng , Gao Yunzhi , Yin Geping
Published: February 2020

At high potential, lithium-ion battery electrolyte solvent will decompose to some extent under different voltages due to their intrinsic instability as well as the catalytic effects on the electrode material surface. The generated gas increases internal pressure of lithium ion battery, namely flatulence phenomenon, and the batteries was prone to explode. Investigating the influence of electrolyte composition, electrolyte salts, electrolyte electrode material during the charging and discharging process, drawing the electrolyte decomposition law will be beneficial to optimize the electrolyte component. In this work, the gas evolution behavior in EC/DMC (volume ratio 1:1) electrolyte system was carried out investigation during the first charging process at high voltage with LiNi0.5Mn1.5O2 material as working cathode. The transmission infrared spectrum testing equipment was shown in Figure 1.

The coin cell for transmission infrared spectrum test was prepared and the test scheme was shown as follows: constant current charging, current density of 20 mA/g; voltage range of 3.5-5.0 V. The infrared spectra is collected every interval 0.1V. The infrared spectra collected in different electrolytes at different voltages during the charging process was given in Figure 2. As seen, the wave number corresponding to different functional groups are listed: absorption peak around 3000 cm-1 corresponds to the -CH symmetrical stretching vibration, absorption peak at 2360, 2340cm-1 corresponds to CO2 gas, absorption peak around 1802, 1770 cm-1 corresponds to C=C bond stretching vibration, the peak around 1282 and 1165 cm-1 corresponds to C-H bending and CF3 degenerate stretching of CHF3.

Figure 1
Operando Mössbauer Spectroscopy Investigations of Li-Ion Batteries and Non-Precious Metal Electrocatalysts for PEM Fuel Cells
Authors: Sougrati Michel , Jumas Jean-Claude , Stievano Lorenzo
Published: February 2020

In the last decade, a growing number of Mössbauer spectroscopy papers dealing with Li-ion batteries and non-precious metal catalysts 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 and tin compounds will be presented (LiFe1-xMnxSO4F, LiFe1-xMnxPO4, TiSnSb 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].

Finally, application of Mössbauer spectroscopy to heat-treated transition iron-NxCy electrocatalysts for O2 reduction in acid PEM Fuel cells will be presented [6].

References:

[1]           (a) J. C. Jumas and P. E. Lippens, Mössbauer Effect Reference and Data Journal  2010, 33., (b) 1. Jaouen, F.. In Non-Noble Metal Fuel Cell Catalysts, Wiley-VCH Verlag GmbH & Co. KGaA: 2014; pp 29-118.

[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]           A. Zitolo, V. Goellner, V Armel, M. T. Sougrati, T. Mineva, L. Stievano, E. Fonda, F. Jaouen. Nat Mater 2015, 14, 937.
Quantitative Life Prediction Using High Precision Coulometry with Automotive Current Rates
Authors: Marcicki James , Masias Alvaro , Coupar Thomas , Elsayed Omar
Published: February 2020

The experimental verification of a Lithium-ion battery for automotive life requirements utilizes significant laboratory resources and calendar time.  If the amount of life testing required to validate a cell design for automotive applications can be reduced, new cell designs could be confidently implemented at lower cost and in shorter time.  High precision coulometry (HPC) has recently emerged as a promising candidate for shortening the time required for validating cell life.  Literature examples have demonstrated improved identification of the mechanisms causing capacity fade1 and qualitative sorting of higher performing cells2.

Academic groups have pioneered this approach but have been primarily limited to testing low currents that are used to probe the rates of side reactions in calendar life scenarios.  Our research focus has been the design, development and validation of a 200 A, high precision (<50 ppm current and <25 ppm voltage) battery tester in partnership with Arbin Instruments and Sandia National Laboratory, with the support of the US Department of Energy (DOE) Advanced Research Projects Agency- Energy (ARPA-E)3.  The capability to perform high precision measurements at currents up to 200 A means the additional degradation brought about by high-rate cycling can be evaluated in addition to calendar assessments.  Additionally, we aim to quantitatively assess performance degradation trends by linking presently measured values to future performance.

Validation testing is presented using 5 Ah prismatic cells to quantify the reduction in test time that is practically achievable using high precision measurements.  Continuous cycle aging using multiple current profiles and ambient temperatures is conducted with periodic reference performance tests.  The mathematical relations between capacity, resistance, coulombic efficiency, and electrode endpoint slippage are leveraged to define various life prediction methods.  The reference performance test measurements from both the high precision tester and standard commercial reference tester are entered as inputs into the life prediction models.  Improved measurement precision can result in reduced uncertainty bands when extrapolating life metric trends into the latter stages of cell life. Enhanced measurement precision can also enable the quantification of long term trends at earlier stages of testing.

References:

A.J. Smith, J.C. Burns, D. Xiong, and J.R. Dahn, J. Electrochem. Soc., 158 (10), A1136 – A1142 (2011).

J.C. Burns, A. Kassam, N.N. Sinha, L.E. Downie, L. Solnickova, B.M. Way, and J.R. Dahn, J. Electrochem. Soc., 160 (9), A1451 – A1456 (2013).

A. Masias, The Bridge – National Academy of Engineering. 45 (1), 13 – 20 (2015).
Assessments on Nafion Modifications of Lithium-Sulfur Batteries--Effects at Different Cell Positions: Sulfur Cathode, Separator and Lithium Metal Anode
Authors: Luo Jing , Wu Nae-Lih
Published: February 2020

The advantages of high specific energy and low cost of sulfur have recently brought rechargeable lithium-sulfur (Li-S) batteries to the spotlight. Yet shuttle effects, mainly caused by polysulfide migration in the electrolyte, remain major technical obstacles to perfect Columbic efficiency and long-term cycle life. Among all the polysulfide trapping methods, the cation-selective Nafion film stands out as a promising physical barrier to the anionic polysulfide species. In this study, a special device has been set up to directly observe the in-operando phenomena of Li-S batteries with various modified components. Effective Nafion modifications of the sulfur cathode, the polypropylene separator (Celgrad 2400) and the lithium (Li) metal anode are compared respectively. A high sulfur-content sulfur/carbon (S/C) nanocomposite with 74 wt% sulfur in the porous carbon (Pearl 2000) matrix is employed as the cathode material. The sulfur cathode is modified by either coating the S/C nanocomposite powder with Nafion or incorporating Nafion into the binder material. Solution casting method is utilized to modify the porous separator and the metallic Li anode surface. The underneath figure shows inhibited polysulfide passage through a Nafion coated separator. The in-operando observations render complementary explanations on the electrochemical performances of batteries with different modified components and give insights to the cell designs of Li-S batteries.

Figure 1