bluuebunny/crossref_metadata_2025 huggingface dataset:
Epitaxial Graphene Nanowalls As Electrocatalysts Supports for Electrocatalytic Reactions
Authors: Lin Yi-Rung , Chou Tsu-Chin , Hsieh Meng-Chia , Chen Kuei-Hsien , Chen Li-Chyong
Published: February 2020

Graphene-based materials, as promising supports for electrocatalysts, attract lots of attention due to its good conductivity, high surface area and chemical stability. However, the influence of such support to the behavior of the catalyst still lacks a unified understanding. Herein, we report, for the first time, a systematic study on the strain effect of substrate toward the catalysts. In this study, we fabricated epitaxial graphene nanowalls (EGNWs) with controllable strain (from tensile, EGNWs-T, to compressive, EGNWs-C) by taking advantages of microwave plasma enhanced chemical vapor deposition, and Pt nanoparticles deposited on EGNWs by RF magnetron sputtering systems, denoted as Pt/EGNWs. It is worth noting that the catalytic properties of Pt on methanol oxidation reactions are highly dependent on the strain of graphene substrates. The catalytic properties of Pt/EGNWs-T shows 100 times higher than that of Pt/EGNWs-C, and the mass activity of Pt/EGNWs-T is 876 A/g, which is almost 10 times higher than that of commercial Pt/C catalysts. In addition to catalytic properties, XANES analysis also gave clear understanding on the electronic state of Pt. We believed that EGNWs provides an excellent opportunity to improve the performance of catalysts by applying different strain on catalysts supports.
Influence of Cathode Potential on Ti Electrodeposition in Molten Fluoride
Authors: Nishikawa Kazuyoshi , Humiya Sawada , Morishige Taiki , Takenaka Toshihide
Published: February 2020

INTRODUCTION

An innovative process of Ti metal production which replaces the Kroll process is desired. Some new production processes have been proposed. Our group has been studying the direct electrolytic smelting of liquid Ti metal above the melting point of Ti in molten fluoride. In our previous reasearches, the cathodic behaviors of Ti ion were investigated in CaF2-MgF2-CaO-TiO2melt above 1373K, and it was shown that Ti metal could be obtained under a suitable condition.In this study, the influence of the cathode potential on Ti electrodeposition has been studied in molten fluoride.

EXPERIMENTAL

The apparatus is schematically shown in Fig.1. A eutectic mixture of CaF2-MgF2 was used, and CaO and TiO2 were added. The molar ratio of CaO to TiO2 in melt was fixed as 1.5 in this study. The mixture was fused at the 1573~1773K.Cyclic voltammetry was applied to clarify the cathodic reaction. A Mo wire (f1mm) was used as a working electrode, and it was covered with a BN sheath except for 3~4mm of its end. A graphite rod (f5mm) was used as a counter electrode. Another Mo wire was used as a quasi-reference electrode. The potential of the quasi-reference-electrode was calibrated by the zero-current potential by Mg deposition and dissolution. Based on the results of the cyclic voltammetry, potentio-static electrolysis was performed to obtain the electrodeposit. The electrodeposit was analyzed by XRD and SEM-EDX.

RESULTS and DISCUSSION

Fig. 2 shows typical cyclic voltammograms in the baths with and without CaO and TiO2 at 1573K.The current density below 0.8V in the bath with CaO and TiO2 was larger than in comparison with that without CaO and TiO2, which suggested that Ti reduction occurred 0.8V.Electrodeposits were obtained by potentio-static electrolysis performed below 0.7V. Ti metal was detected in the deposit obtained at 0.2~0.4V by XRD, while only Ti oxides were detected in the deposit at 0.5~0.7V.

Small particles containing Ti were found in the electrodeposit by SEM obvervation. Fig.3 shows the relationship between the cathode potential and the atomic ratio of O to Ti of the particles by EDX. These results clearly indicate that the particles obtained above 0.5V were Ti oxides and that at 0.4V was Ti metal, which agrees well with the results by XRD. The Ti metal particle was not found in the deposits obtained below 0.3V. Because Ti metal was detected in these deposits by XRD, Ti metal particles were too small to be found by SEM observation.

It was confirmed that the cathodic current below 0.8V in CaF2-MgF2-CaO-TiO2corresponded to the Ti reduction; a Ti ion was partially reduced at 0.5~0.8V, and Ti metal was obtained below 0.4V.

AKNOWLEDGMENT

This study was supported by the New Energy and Industrial Technology Development Organization (NEDO) under the “Innovative Structure Materials Project (Future Pioneering Projects)”, and by Kansai University Grant- in Aid for Progress of research in graduate course, 2011.

Figure 1
Ionic Liquid Polymer Electrolyte Based on Bis(fluorosulfonyl)Amide for Sodium Secondary Batteries
Authors: Ab Rani Mohd Azri , Matsumoto Kazuhiko , Hagiwara Rika
Published: February 2020

The development of non-flammable electrolytes has been extensively studied to reduce the drawbacks caused from organic solvents. In this study we have successfully demonstrated the use of Ionic Liquid Polymer Electrolyte (ILPE) as a separator for sodium ion battery by using polyvinyl chloride (PVC), in combination with the previously reported ionic liquid electrolyte, Na[FSA]-[C2C1im][FSA] (FSA = bis-(fluorosulfonyl)amide and C2C1im = 1-ethy-3-methylimidazolium)1. The ILPE was prepared by casting method in which PVC acts as a host polymer. The different ratio of [C2C1im][FSA] was added into the THF solution of PVC/NaFSA (1:1). The highest ionic conductivity was achieved with addition of 42.9% ionic liquid into the system which resulted in 1.49 mS/cm at 25 °C. The deposition and dissolution of Na metal has been observed around 0 V vs Na/Na+ by cyclic voltammetry. The reversible capacity of 92 mA g-1 was obtained at 363 K for a Na2FeP2O7 positive electrode in the Na/PVC-Na[FSA]-[C2C1im][FSA]/ Na2FeP2O7-cell  (theoretical value is 97 mA g-1).  This result suggests that the ILPE is a promising separator for sodium secondary battery where safety and cost are main concern.

1.         Matsumoto, K.; Hosokawa, T.; Nohira, T.; Hagiwara, R.; Fukunaga, A.; Numata, K.; Itani, E.; Sakai, S.; Nitta, K.; Inazawa, S., The Na[FSA]–[C2C1im][FSA] (C2C1im+:1-ethyl-3-methylimidazolium and FSA−:bis(fluorosulfonyl)amide) ionic liquid electrolytes for sodium secondary batteries. Journal of Power Sources
2014,
265, 36-39.
Investigation on Improved Electrochemical Performance of Layered Sodium Manganese Oxide By Partial Transformation of P2-Phase to O3-Phase for Sodium Ion Battery
Authors: Yang Junghoon , Kang Yong-Mook
Published: February 2020

Layered structure sodium manganese oxides are the most popular cathode materials for sodium ion battery due to their superior electrochemical performances with low cost. There are various structures of sodium manganese oxides based on the transition metal stacking arrangement and the coordination of Na ions in the structure. Among various structures of the layered structure materials, sodium manganese oxide has two representative structures which are P2- and O3- phases. The letter denoted as P and O indicates the trigonal prismatic and octahedral coordination of Na ions in the structure, respectively. And the number of transition metal layer in unit cells is written after the letter. Therefore, P2- and O-3 type phases have trigonal prismatic and octahedral sites for Na ions occupying, and two and three different MnO2 layers per unit cell, respectively. Generally, P2- and O3-type materials exhibit different intrinsic electrochemical behaviour due to their different Na ion occupation sites and Na ion concentrations. The P2-type materials show low initial charge capacity due to large unoccupied Na ion site and low reversible capacity. The low initial charge capacity cause severe problem when it is adopted as a cathode for full-cell system. O3-type materials provide higher initial capacity and reversible capacity than P2-type materials. However, O3-type materials exhibit lower Na ions diffusivity because Na ions should diffuse through face-shared interstitial tetrahedral sites in the structure. Furthermore, they show fast degradation when it is charged above 4.0V due to structural instability.

In this study, we provide the enhanced electrochemical performances of sodium manganese oxide by partial transformation from P2-type to O3-type phase. The P2- and O3- mixed phase suggest the novel ways to overcome the disadvantages of each phase, by adopting the advantages of opponent phase. The mixed phase for layered structure cathode materials present the new ways for the development of cathode materials with improved properties.
Synthesis, Electrochemical Properties of 3D Structured Red P-Carbon As an Anode Material for Na-Ion Battery
Authors: Kim Joo-Hyung , Lee Hyun-Wook , Yun Jong Hyuk , Kim Do Kyung
Published: February 2020

Li ion batteries have become widely accepted as an effective device for storing electric energy in recent decades. In practice, it can play an important role in present energy industries for offering the highest energy density. However, there are still problems to be solved such as limit in remote, cost, and safety. To date, Na ion batteries has been considerably interested in the field of large energy storage system (ESS) because of needs to go beyond the limits of Li ion batteries. Extensive investigations on alloying reactions of various transition metal (Sn, Sb, Ge, Si etc) as anode materials have been carried out because of their high theoretical capacity. Inspired by this point, phosphorus is one of the most promising candidate with a high theoretical specific capacity (2596 mA h g-1) at the discharge potential range of 0.4-1.2 V. In this paper, we have synthesized 3D structured red P-Carbon composite by facile templating method. For this process, we anticipated a lot of merits such as suppressing the large volume expansion (~300%), offering large reaction site, and minimizing the unnecessity like binders and additives. The phase and morphology of 3D structured red P-Carbon has been investigated by XRD, SEM, and TEM, respectively. The electrochemical performance of red P-CNT composites were tested in sodium non-aqueous electrolytes. It could maintain the reversible capacity in high C-rate because of their structural advantage. In addition, differences of structural phase differences and conductivity during the alloying reactions in sodium system will be discussed.
Development of a Low Power Ammonia Gas Sensor
Authors: Navaei Milad , Hesketh Peter
Published: February 2020

In recent years, there has been significant growth in gas sensor industries given their ability in detecting explosives, pollution, and toxic gases. In fact, one of the most highly toxic gases is Ammonia, which is widely produced in industries such as chemical, fertilizer, and food processing. In chicken farms, the Ammonia produced from the excretes of the chickens show decrease in the quality and quantity of egg and meat production, and may inhibit growth in cell lines.

A miniature, low-power, thermal conductivity sensor has been developed. The sensor was batch fabricated and is CMOS-compatible. Joule heating is the main driving principle behind Thermal conductivity sensors where the Polysilicon micro-bridge is heated by applying a fixed current while measuring the resistance change of the bridge as it interacts with the surrounding gas.To better understand the sensor performance and sensitivity, the sensor was simulated in COMSOL Multiphysics by coupling the electrical and thermal physics. The model results show the temperature distribution of the heated mico-bridge. Furthermore, steady state response as well as transient response of the sensor were studied. The transient response provides more information about the physical properties of the gases such as thermal conductivity and thermal capacity. The COMSOL simulation revealed that having a wider anchors and suspending the bridge from the substrate will improve the temperature uniformity, which ultimately improve the detector performance and reduce the heat loss through the substrate.

Furthermore, an electrical circuit was developed to measure the resistance change of the sensor with high accuracy while reducing the signal to noise ratio. Teensy 3.2 was used to excite the sensor at a fixed frequency and measure the change in resistance. The resistance value of the sensor was then transmitted to a cell phone to be analyzed. There are three resistance components in this circuit which are the sensor (RSensor), reference sensor (RR), corresponding resistance (R), and an op-amp (OPA1324). In order to measure the change in resistance of the TCD, the value of RR and R were fixed (RR =3010 Ω and R=332 Ω), and the output voltage of the op-amp was measured using .The sensor was first tested in air, helium and 0.01% ammonia. The sensor shows good sensitivity to low ppm levels of Ammonia at the room temperature. The sensor performance measurements in less than 0.2 ms while consuming 5 nJ per reading.
Graphene Oxide-Based Supercapacitor Immunosensor for D-Dimer Detection
Authors: Rodriguez-Silva Allen Armando , Movil-Cabrera Omar , Staser John A
Published: February 2020

The constantly-evolving field of biosensors has attracted the focus of attention of the biomedical field due to their outstanding capacities for performing real-time in-vivo non-invasive studies for biomarkers detection and quantification. Furthermore, the field of electrochemical biosensors has been of increase interest given its potential to easily convert biological phenomena into an electrical measurable signal. By using supercapacitors as a potential technique for developing biosensors, we have been able to target specific human serum proteins, in this case, D-Dimer. By utilizing graphene oxide as a base nanocomposite for antibody fixation, we have been able to immuno-functionalize an electrode with monoclonal antibodies and target this biomarker which has been identified as a target molecule for diagnosis of venous thromboembolism-related conditions. Nanocomposite characterization and electrode immuno-functionalization was studied with Fourier transform infrared (FTIR), Raman spectroscopy (RS), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). Finally, antibody-antigen interactions for D-Dimer detection were studied with cyclic voltammetry (CV) in a 3-electrode configuration.
Amperometric Gas Sensors: From Classical Industrial Health and Safety to Environmental Awareness and Public Health
Authors: Carter Michael T , Stetter Joseph R , Findlay Melvin W , Meulendyk Bennett J. , Patel Vinay , Peaslee David
Published: February 2020

KWJ Engineering and SPEC Sensors LLC have been working to develop and commercialize a new class of amperometric gas sensor, the screen-printed electrochemical sensor (SPEC) for the past several years. These new, tiny, ultralow power sensors and device built around them are making in-roads in a diverse set of endeavors. Much of this potential has been driven by the explosion of interest and activity in sensor technologies driven by our increasingly connected world (Internet of Things). Amperometric gas sensors were once found mainly in industrial hygiene applications, e.g., four gas monitors, confined space entry monitoring and leak detection. Conventional sensors are fairly large, although not requiring particularly high power (on the order of tens of milliwatts). However, they are not compatible with modern needs. The advent of tiny form factors with the SPEC sensor has opened up new possibilities in applications requiring portability, wearability (e.g., watches or other personal monitoring devices) and self-powered or long-term unattended battery operation by virtue of the very small size and ultralow power (microwatt) requirements.

This paper will review several recent efforts in next-generation gas sensor development and applications at KWJ Engineering. Major scientific directions include portable and wearable environmental monitoring of inhalation hazards for personal and public health protection and detection and classification of odors.
Pumping Induced By Bio-Mimetic Magnetic Micro-Cilia in Creeping Flows
Authors: Hesketh Peter , Hanasoge Srinivas , Ballard Matt , Erickson Marilyn , Xu Jie , Alexeev Alexander
Published: February 2020

The inertial effects in creeping flow regimes are negligible. Most motile micro-organisms manipulate fluid by oscillatory Cilia or Flagella. The pumping action by a cilium is attributed to the asymmetry in the power and recovery strokes. Further, the ratio of viscous forces to Elastic forces (given by sperm-number) on a cilium determines the efficiency of the pumping. In this presentation we demonstrate magnetic micro-cilia based pumping techniques. We experimentally determine the optimum sperm-number for maximum pumping efficiency. For this, we surface micro-machine high aspect ratio cilia, which are actuated magnetically. These micro-features are fabricated by evaporating NiFe alloy at room temperature, on to patterned photoresist. The evaporated alloy curls upwards when the seed layer is removed to release the cilia, thus making a free standing ‘C’ shaped magnetic microstructure. This is actuated using an external rotating permanent magnet. The time period for the power stroke and recovery stroke are different, which determines the asymmetry in the cilium trajectory. This manipulates the fluid around it. We also demonstrate the active mixing these cilia can produce in the microchannel. We suggest the use of these micro-cilia in capturing bacteria. Selective immobilization of the cilia can lead to highly specific capture of bacteria. We predict high capture rates which will enable easy detection. These simple to fabricate micro cilia can easily be incorporated into many microfluidic systems which require high pumping, mixing and capture efficiencies. The figure bellow shows an image of Cilia actuated by an external magnetic field.

Figure 1
Anion Conducting Multiblock Copolymers
Authors: Liu Lisha , Ahlfield John M. , Kohl Paul A
Published: February 2020

Anion Exchange Membrane (AEM) fuel cells are a possible route to overcoming fundamental issues with acid-based fuel cells. The issues include the high cost of platinum catalysts, complex water management, and sluggish electrochemical reactions. However, the performance of AEM fuel cells is not as good as that of Proton Exchange Membrane (PEM) fuel cells partially because of the limitations of current anion exchange membranes, such as low ionic conductivity, poor stability at high pH, and high water uptake.

A series of partially fluorinated multiblock copoly(arylene ether)s with long head-group tether were synthesized for use in AEM fuel cells and electrolyzers. The multiblock copolymers were synthesized via polycondensation of hydroxyl-terminated oligomers and fluoro-terminated oligomers. The resulting multiblock structure has one hydrophilic block and one hydrophobic block. It was designed so that nanophase-separation occurs and efficient conductive channels are formed with low water uptake. Multiblock copolymers with different block lengths and ion exchange capacity (IEC) were synthesized to maximize ion conductivity and explore the relationship between chemical structures and membrane properties. A non-linear relationship was found between the number of head-groups on a hydrophilic block and the conductivity. Doubling the number of head-groups more than doubled the hydroxide conductivity. Hydroxide conductivity as high as 119 mS/cm at 80°C have been observed with a specific size block size: X5.4Y7, where X is the hydrophobic block and Y is the hydrophilic block. The hydrophobicity of the backbone has allowed synthesis of polymers with minimal water uptake. The ratio of conductivity-to-water uptake shows that less water is absorbed compared to conventional materials. The number of waters per ion within the polymer is as low as 4. This is reflected in the measurement of the amount of free-water and bound-water. No conductivity loss was observed after soaking the membrane in 1M NaOH solution at 60°C for over 700 hours.

Financial support from US Office of the Deputy Assistant Secretary of the Army for Defense Exports and Cooperation (DASA-DE&C) is gratefully acknowledged.
CFD Analysis of Aggregation and Breakage of Li-Ion Precursor in Taylor-Reactor
Authors: Lee Seung-Hun , Jeon Dong Hyup , Song Jung-Hoon
Published: February 2020

In this work, aggregation and breakage of Li-ion precursor in Taylor-reactor are studied for various simulation condition, i.e., agitation rate, particle property, and reactor direction. The mean particle size and distribution is important to electrochemical performance of cathode materials. The population balance equation (PBE) is solved for coupling between particle interaction and fluid dynamic. The quadrature method of moments (QMOM) is implemented in a commercial computational fluid dynamics (CFD) code. Sum of three aggregation kernels, such as turbulent, Brownian, and Stokes aggregation, is considered for the calculation. [1] Breakage kernel is a combination of power-law kernel and various daughter distribution functions. Collision efficiency is assumed to be equal and the precursor is considered as spherical particle. Three-dimensional analysis is implemented and the simulation results are compared with experimental data.

[1] L. Claudotte, N. Rimbert, P. Gardin, M. Simonnet, J. Lehmann, and B. Oesterle, AIChE J., Vol.56, No.9, pp. 2347-2355 (2010)
High Rate, Stable Porous Silicon Deposition By Thermal Plasma Technology
Authors: Bosch Roel C.M. , Borsa Dana M. , Mulder Fokko M.
Published: February 2020

Meyer Burger (Netherlands) B.V. is a manufacturer of industrial high speed deposition equipment. Our thermal plasma deposition technology has been used since two years to produce thick silicon coatings on metal foils for battery applications. In several collaborations we have demonstrated high quality coatings at high deposition speed (>10 micron / min) on 3D structured current collectors, where coating stability (cycle life) is obtained by growth parameters and porosity of the amorphous coatings. In one example we have used this growth process to deposit 2.1 mg/cm2 silicon on a thin conductive foil which resulted in a stable capacity level of around 1000mAh/g after 100 cycles (testing ongoing at Delft University of Technology).

The presentation will show more details on the deposition technology, growth mechanism and the properties of the thick stable silicon coatings. The economics of volume production (€ / kWh) with our 2-side R2R coating equipment for 100% silicon based anodes will also be highlighted and compared to nowadays slurry-based coating technologies.

Figure 1
Enhanced Performance of Different Carbon Coated Nano-LiFePO4/C Composites for Lithium Battery By Vacuum Thermal Decomposition
Authors: Huang Xiao-peng , Yao Yao-chun , Liang Feng , Du Yuan-chao , Dai Yong-nian
Published: February 2020

Nano-LiFePO4/C composite cathode materials were synthesized by vacuum thermal decomposition method, using sucrose, polyvinyl alcohol (PVA) and citric acid (CA) as different carbon sources. The samples had systematically been investigated with X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectroscopy, element analysis, electrochemical impedance spectroscopy and charge/discharge measurements. Under vacuum sintering condition, the thermal decomposition rate of organic carbon source was significant accelerated and active carbon were formed to coat LiFePO4 particle. The obtained LiFePO4/C sample showed highly crystalized olivine-type structure and spherical-like particles of 100-300 nm, delivering an enhancement of rates capacity than traditional argon sintered LiFePO4/C material. Besides, the effect of different carbon sources (sucrose, PVA and CA) on the properties of LiFePO4/C composite was paid special attention. SEM and TEM analysis showed that all the LiFePO4/C samples had nano size particle but differ in carbon morphology and layer thickness. After vacuum thermal decomposition, the residual carbon content decomposed by sucrose, PVA and CA was about 2.5%, 3.1% and 1.8%, respectively. EIS spectra indicated that the sucrose coated LiFePO4/C electrode had the lowest charge transfer resistance (Rct=50 Ω) and highest lithium diffusion coefficient. As a consequence, the sucrose coated LiFePO4/C synthesized under vacuum decomposition exhibited the best discharge capacity of 155.1, 153.7, 148.6, 140.3, 123.9 and 80.1 mA·h·g-1 at 0.2 C, 0.5 C, 1 C, 2 C, 5 C and 10 C, respectively. The results indicated that organic carbon sources can be prior carbonized and the performance of LiFePO4/C composite can be further improved by vacuum thermal decomposition.
Facile Redox Synthesis of Layered LiNi1/3Co1/3Mn1/3O2 for Rechargeable Li-Ion Batteries
Authors: Baboo Joseph Paul , Gim Jihyeon , Song Jinju , Kim Sungjin , Jo Jeonggeun , Pham Duong Tung , Kim Seokhun , Yang Juhyun , Kim Jaekook
Published: February 2020

The increasing demand for energy storage devices has motivated the need to find environmentally friendly, high energy density, and cost-effective materials for energy storage and suitable synthesis techniques. In this work, we report a simple and cost-effective chemical route, in which intermediate Ni1/3Co1/3Mn1/3(OH)2 product was primarily prepared using a simple redox synthesis technique at ambient temperature. Lithiation reactions were then performed at higher temperatures to develop the final layered Lix(Ni1/3Co1/3Mn1/3)O2 structure (where x= 1.0 and 1.05). The lithium content was varied in order to analyze the effect of excess lithiation on the structural and electrochemical properties of the layered-type Li(Ni1/3Co1/3Mn1/3)O2 cathode. The XRD studies clearly confirmed the formation of layered-type structures corresponding to hexagonal α-NaFeO2 (space group R-3m). The ICP studies confirmed the stoichiometric chemical composition (Li(Ni0.32Co0.33Mn0.31)O2) of the prepared samples. FE-SEM images revealed that the particle growth occurred when the particles were heated at elevated temperatures of 950°C, and the average particle diameter was around a few micrometers. The electrochemical tests performed versus lithium indicated that competitive specific capacity values were registered for all the prepared cathodes and the capacity retention was impressive on repeated charge/discharge cycling within the potential range of 3.0 – 4.3 V and a current density of 14 mA/g. In particular, the Li(Ni0.32Co0.33Mn0.31)O2 sample demonstrated the highest capacity retention value (~ 99%) after 50 cycles and better rate performances of 104, 91, 76, and 67 mAh/g at higher current densities of 229, 457, 914, and 1429 mA/g respectively.
On the Versatility of Melt-Synthesis of LiFePO4 cathode Material
Authors: Talebi-Esfandarani Majid , Rousselot Steeve , Jin Liling , Bibienne Thomas , Gauthier Michel , Chartrand Patrice , Sauriol Pierre , Seifitokaldani Ali , Liang Guoxian , Dollé Mickael
Published: February 2020

LiFePO4 (LFP) has attracted much attention as a promising candidate for cathode materials in new generation of Li-ion batteries due to its good thermal stability, being environmentally friendly and abundance in nature. Many synthetic routes, such as solid state, sol-gel, hydrothermal, co-precipitation, and microwave preparations, have been used for preparing LFP. In 2003, Gauthier et al. advanced the concept of melt synthesis. The process operating above 1000°C in the liquid phase, benefits from fast reaction kinetics and the thermodynamic stability of LiFePO4 in a reducing atmosphere. This approach allows the use of a wide range of simple raw materials as well as a possible purification strategy in the melt or upon solidification, potentially enabling for usage of less pure non-expensive raw materials.

Fundamental aspects will be addressed as this work is only feasible with a good understanding of the thermodynamics of the Li-Fe-P-O system. A model has been developed and it is supported by our experimental data. On this basis, recent experimental observations and progress on raw material selection and systems will be then reported. Melt-synthesis conditions and the latest result in controlling the purification of LiFePO4 from major phase impurities will also be covered. All these considerations allow the selection of the best conditions to prepare a high purity LiFePO4 by melt-process.

This work is part of an Automotive Partnership of Canada supported program to develop and pilot the molten-synthesis process to make high purity C-LiFePO4 with excellent electrochemical properties for using as a cathode material in Li-ion batteries for EVs and PHEVs application.
A Risk Assessment Methodology to Prioritise Risks in Large, Stationary Li-Ion Battery Systems
Authors: Mulder Grietus , Trad Khiem
Published: February 2020

Performing a risk analysis is the basis in all engineered products. No specific methodology exists for stationary batteries. Indications on the needed risk assessment may be derived from standards that cover large stationary Li-ion battery storage systems in their scope [1]. However, they hardly go further than referring to the general risk assessment techniques with as examples Failure Mode and Effect Analysis (FMEA) and Fault Tree Analysis (FTA). Despite this lack of specific guidance, a risk assessment for large battery systems has their uniqueness due to their structure. There are many levels between battery cells and the complete system. Moreover, a huge number of cells are used that must be correctly dealt with in the assessment. In the scientific literature only a few papers are dedicated to risk assessment on batteries.

This contribution sets up a complete framework of methodologies and protocols for safety testing of stationary Li-ion batteries for large-scale grid-connected applications. The risk assessment is based on the well-known Failure Mode Effects Analysis (FMEA) method. In a first step, a generic hierarchical system diagram of a stationary battery is developed to be used as the system under study in the FMEA. To improve the completeness and the objectivity of the analysis, improvements to the FMEA methodology are proposed and used. The main goal of these improvements is to limit the dependency on expert judgement and inspiration and to improve the prioritization of risks without adding unnecessary complexity. A core issue is that the method of calculating the Risk Priority Number (RPN) is not sufficient fo large battery systems. This problem was also detected by [2]. The RPN does not take suitable care of the numbers of cells, modules, etc. and has no aggregation per level. Risks that are mitigated on several system levels have to be aggregated in an advanced RPN methodology. This leads to a thorough risk assessment, in which it is easy and meaningful to select the most prominent project risks.

This contribution is an outcome of the European FP7 project Stallion. The project has set up safety tests beyond state of the art for stationary Li-ion battery systems. It also resulted in a handbook on battery system safety for the broad audience [3].

[1]       Survey on standards for batteries and system integration with them. VITO, 2015. [Online] batterystandards.vito.be.

[2]       Analysis of Battery Safety and Hazards’ Risk Mitigation. Ashtiani, C.N. 2008, ECS Transactions, Vol. 11, pp. 1-11 .

[3]       STALLION Handbook on safety assessments for large-scale, stationary, grid-connected Li-ion energy storage systems, DNV GL, Arnhem 2015. [Online] stallion-project.eu

Figure 1
Safe Discharge of Damaged Li-Ion Batteries with Redox-Shuttle Additives
Authors: Wachtler Mario , Emmermacher Brita , Wohlfahrt-Mehrens Margret , Döring Harry
Published: February 2020

Due to continuous research and development efforts, the intrinsic safety of Li-ion batteries (LIBs) has increased significantly over the last years. A critical issue to resolve remains the question what to do with damaged LIBs in the charged state. Batteries can contain protection mechanisms, the activation of which may result in situations where the battery cannot be electrically discharged any longer.

This contribution presents a safe way of discharging batteries at a cell level using water, aqueous salt solutions, or organic solutions of redox-shuttle additives as discharge agents. The discharge solutions can be added to the cell from the outside when discharge is required, or, in case they are already contained in the cell, they can be activated by adequate technical trigger mechanisms.

A number of examples of compounds is shown and compared for 20 Ah prismatic Li-ion cells. Typical discharge times are in the range of 30 to 60 hours (shorter times are expected for higher concentrations of the discharge agents than tested here). The end-of-discharge voltage is typically between 0 and 1 V, depending on the respective discharge agent. Discharge with water and aqueous solutions is the cheapest way of discharge, but since it is accompanied by gas evolution, it may cause secondary risks via the evolved gas. The organic solutions of redox-shuttle additives enable a complete discharge without any gas evolution, and are thus the safer option (cf. Figure: Evolution of cell voltage after addition of redox-shuttle additives). During discharge the chemical energy contained in the charged cell is converted into thermal energy. For the timescale of the given experiment, however, no noticeable heating of the cell was observed (with the temperature changes remaining < 3 °C, which was within the natural variation of the ambient temperature).

The underlying discharge reaction mechanisms are explained and requirements and limitations for the discharge agents are discussed.

Acknowledgement: Financial support of parts of this work from the German Association of the Automotive Industry (VDA) is gratefully acknowledged.

Figure 1
Correlation Between Solvation Structure and Ion-Conductive Properties of Highly-Concentrated Poly(ethylene carbonate)-Based Electrolytes
Authors: Kimura Kento , Tominaga Yoichi
Published: February 2020

Ion-conductive solid polymer electrolytes (SPEs) are of great interest as key materials to realizing safe and flexible rechargeable batteries, particularly Li batteries. Since the discovery of ionic conductions in poly(ethylene oxide) (PEO)/metal salt complexes, numerous efforts have been made to improve their electrochemical properties. However, it is difficult to increase Li-ion conductivity that is the product of overall conductivity and Li transference number (t
+). This drawback mainly arises from excessively tight complex structures between polar polymers and Li ion.

To overcome the drawback and create all-solid-state batteries based on SPEs, we specifically focus on poly(alkylene carbonate)s derived from CO2/epoxide copolymerization as SPE polymer hosts [1,2]. Consequently, we have found an unusual ion-conductive behavior of poly(ethylene carbonate) (PEC)-based electrolyte, including high ionic conductivity of highly-concentrated electrolytes and extremely high t
+, which in some cases is above 0.8 [3,4]. In this PEC-based electrolyte system, ionic conductivity continues to increase with increasing salt concentration, which is a behavior scarcely shown in conventional electrolyte systems. In addition, we have already confirmed operations of prototype Li/LiFePO4 cells based on PEC-based electrolytes combined with plasticizing and reinforcing additives [5,6].

In this context, we considered that elucidation of salt solvation structure is a key to better understanding the origin of the particular ion-conductive behavior, and improving the performance further. In the present study, we adopted spectroscopic studies including FT-IR, Raman spectroscopy, and solid-state 7Li magic angle spinning (MAS) NMR for PEC/lithium bis(fluorosulfonyl)imide (LiFSI) electrolytes with varying concentration. The FT-IR and Raman spectroscopy indicate that most FSI ions interact with more than one Li ion at high concentration region, which is referred to as aggregates, while C=O groups dissociates the salt. The 7Li MAS NMR suggested that a relatively weak contact between Li ions and FSI ions withdraws Li ions from a strong interaction with C=O groups. We conclude that this moderate complex structure, where C=O groups allows the highly concentrated ions to remain amorphous and mobile, leads to reasonable conductivity with extremely high t
+. We believe that this finding will provide a new insight for developing SPEs having both high conductivity and high t
+ simultaneously.

References:

[1] Y. Tominaga, T. Shimomura, M. Nakamura, Polymer, 51, 4295 (2010).

[2] M. Nakamura, Y. Tominaga, Electrochim. Acta, 57, 36 (2011).

[3] Y. Tominaga, V. Nanthana, D. Tohyama, Polymer J., 44, 1155 (2012).

[4] Y. Tominaga, K. Yamazaki, Chem. Commun., 50, 648 (2014).

[5] K. Kimura, J. Hassoun, S. Panero, B. Scrosati, Y. Tominaga, Ionics, 21, 895 (2015).

[6] K. Kimura, H. Matsumoto, J. Hassoun, S. Panero, B. Scrosati, Y. Tominaga, Electrochim. Acta, 175, 134 (2015).
Solvent Effect on the Kinetics of Lithium-Ion Intercalation Reaction
Authors: Nikitina Victoria A. , Vassiliev Sergey Yu. , Levin Eduard E.
Published: February 2020

In spite of the great number of commercialized lithium-ion intercalating systems, the intrinsic ion-transfer kinetics of the intercalation reaction is still poorly understood. The process of Li-ion intercalation comprises several stages: i) diffusion of Li ion in solution; ii) partial or complete desolvation of Li+ at the interface; iii) diffusion of the ion through cathodic or anodic SEI at the electrode surface; iv) insertion of the Li ion into the lattice of the material, which is accompanied by the transition metal ion oxidation/reduction. Under these conditions, a pronounced solvent effect on the kinetics of the process is expected, as solvent determines both the structure of the interface (SEI composition) and the desolvation energy, which contributes to the activation barrier. Construction of a self-consistent kinetic model requires careful experimental examination of all of these stages and determination of the limiting stage of the process.

    In this work we focus on the solvent effect on the kinetics of lithium ion intercalation into model electrodes (LiCoO2, LiMn2O4, V2O5, etc.), as these systems are characterized by different redox potentials and, correspondingly, by different SEI compositions.  We report the results of the electrochemical measurements for the model electrode materials in carbonate-based electrolytes (e.g. commercial electrolyte ethylene carbonate/dimethyl carbonate), protic solvents (water, ethylene glycol) and aprotic solvents (dimethyl sulfoxide, acetonitrile). For these groups of solvents we report the results of cyclic voltammetry numerical modeling, which allows for the determination of the intrinsic kinetic parameters of the intercalation reaction1 (diffusion coefficient, rate constant and the parameters of the intercalation isotherm). To construct an accurate kinetic model of the intercalation process the real particle size distribution, as determined from scanning electron microscopy data, is taken into account.

    The observed tendencies in the rate constant values are compared with the results of quantum chemistry calculations on the DFT level of theory of the desolvation energies for the lithium ion in the solvents under study. The calculations were carried out using “cluster-continuum” approach, which allows separating the electrostatic and the non-electrostatic (specific) contributions to the overall desolvation barrier.  The combination of the electrochemical experimental data with the results of molecular modeling allowed us to draw conclusions on the solvent effect on the intercalation reaction kinetics and the contribution of the lithium ion desolvation energy to the overall activation  barrier.

S. Yu. Vassiliev, E. E. Levin, V. A. Nikitina. Kinetic analysis of lithium intercalating systems: cyclic voltammetry. Electrochim. Acta,  doi:10.1016/j.electacta.2015.12.172.
Solid State Electrolytes for Next-Generation Lithium Ion Batteries
Authors: Narayanan Sumaletha , Thangadurai Venkataraman
Published: February 2020

Lithium ion batteries achieve much attention because of their wide applications ranging from portable electronics to transportation and grid storage. The next-generation lithium ion batteries require a highly conducting solid electrolyte which ensures safe operation. Garnet-type oxides with nominal chemical formula, Li5La3Ta2O12 are promising Li+ conductors which show high ionic conductivity, low electronic conductivity and electrochemical stability.1 It is important to understand the fundamental electrical transport mechanism of these garnet-type solid-state Li+ conductors with respect to change in temperature and lithium content in the structure. Li+ stuffing into Li5La3Ta2O12 have proven to improve the ionic conductivity of garnet-type oxides.2 The present study reports highly conducting lithium-stuffed Li5+2xLa3Ta2-xYxO12 (0.05 ≤ x ≤ 0.75) electrolytes.3 Effect of Y3+ and Li+ doping in Li5La3Ta2O12 on the structural, morphological and electrical properties are studied in this work. Detailed analysis of crystal structure, and electrical and dielectric properties are also performed, in order to investigate the Li+ migration pathways in the crystal structure, using different techniques such as powder X-ray diffraction, solid state 7Li MAS NMR, and electrochemical impedance spectroscopy.3-4 The x = 0.50 and 0.75 members in the series of Li5+2xLa3Ta2-xYxO12 have exhibited highest conductivity of ~ 10-4 Scm-1 at 23 ºC. In addition, their stability in aqueous LiCl solution make them suitable candidate as protective layers for lithium electrodes in lithium-air batteries.3

References

1.Thangadurai, V.; Kaack, H.; Weppner, W. J. F. J. Am. Ceram. Soc.
2003, 86, 437-440.

2. Thangadurai, V.; Narayanan, S., Pinzaru, D. Chem. Soc. Rev.
2014,43, 4714-4727.

3. Narayanan, S.; Ramezanipour, F.; Thangadurai, V. Inorg. Chem.
2015,
54(14), 6968-6977.

4. Baral, A. K.; Narayanan, S.; Ramezanipour, F.; Thangadurai, V. Phys. Chem. Chem. Phys.
2014, 16, 11356-11365.
Enhanced Physical and Electrochemical Properties of LLBTZO Garnet Structures for Energy Storage Applications
Authors: Farooq Umer , Samson Alfred , Pilapil Brandy , Ganjeh Anzabi Pejman , Trifkovic Milana , Thangadurai Venkataraman , Roberts E.P.L.
Published: February 2020

In recent years, an intensive research has been conducted to introduce the solid-state electrolytes for the future Li-ion batteries [1-2]. In this work we prepared a ceramic electrolyte Li6.5 La2.5 Ba0.5 Nb Zr O12(LLBNZO) and sintered pellets of as-prepared material at elevated temperature ranging from 1050 to 1200 0C. The objective of this research was to observe the effect of temperature on porosity, density and transport properties of materials. Preliminary results suggest that the material sintered at higher temperature could show enhanced performance in terms of fast ionic transport. This enhancement in performance can be attributed to low porosity of materials which is result of high temperature sintering.

References:

1- V. Thangadurai, D. Pinzaru, S. Narayanan, and A. K. Baral, "Fast Solid-State Li Ion Conducting Garnet-Type Structure Metal Oxides for Energy Storage," J. Phys. Chem. Lett. 6, 292−299 (2015).

2- J. Schwenzel, V. Thangadurai and  W. Weppner , 'Developments of High-Voltage All-Solid-State Thin-Film Lithium Ion Batteries,' J. Power Sources 154, 232-238 (2006).
Gel Membranes for Lithium Ion Batteries
Authors: Zhu Yusong , Li Minxia , Fu Lijun , Wu Yuping
Published: February 2020

To improve the safety and promote the cycling life of lithium ion batteries, a lot of work has been done on gel polymer electrolytes, which can act as separator and electrolyte. The key is the gel membrane. Some former work delivers quite some misunderstandings such as requirements on mechanical strength, porosity and shut-down performance on gel membranes. Here we will expound our pioneering work from fundamental research to the commercial products, which is unique over the world.

 

Acknowledgment:

Financial support from Natural Distinguished Youth Scientists Project of China (No. 51425301), NSFC (21374021), STCSM (14520721800) and Natural Science Foundation of Jiangsu Province (BK20151534) is greatly appreciated.

 

References:

[1] Y.S. Zhu, F.X. Wang, L.L. Liu, S.Y. Xiao, Z. Chang, Y. P. Wu, Energy Environ. Sci., 6, 618-624 (2013).

[2] Y.S. Zhu, S.Y. Xiao, Y. Shi, Y.Q. Yang, Y.Y. Hou, Y.P. Wu, Adv. Energy Mater., 4, 1300647 (1-9) (2014).

[3] S.Y. Xiao, Y.Q. Yang, M.X. Li, F.X. Wang, Z. Chang, Y.P. Wu, X. Liu, J. Power Sources, 270, 53–58 (2014).
In Situ TEM Investigation of Structural Evolution of Black Phosphorous Anode for Sodium Ion Batteries
Authors: Nie Anmin , Cheng Yingchun , Mashayek Farzad , Shahbazian-Yassar Reza
Published: February 2020

Na-ion batteries have attracted enormous interest due to its low cost and the abundance of sodium in the earth, holding the potential to become the technology of choice for large-scale electrochemical energy storage. However, the investigation of suitable anode materials for Na-ion batteries is still in its infancy and few electrode materials meet the performance requirement for practical applications. Black phosphorous (BP), which possesses layered structure, is a promising anode material for sodium ion batteries due to its extremely high theoretical capacity (2596 mAh/g) and good conductivity. However, there are few studies on the electrochemical reaction between BP and sodium.1,2 Here, we explored the structural evolution of BP during the sodiation reaction by employing a state-of-the art in situ (scanning) transmission electron microscopy electrochemical testing technique.3,4 Our in situ TEM study indicates that the sodium ion transport pathway is highly orientation dependent inside the BP. An anisotropic expansion and multiple phase transitions  are also observed during the sodiation process.

[1] Park, C. M.; Sohn, H. J.
Adv. Mater.
2007, 19, 2465-2468

[2] Sun, J.; Lee, H.-W.; Pasta, M.; Yuan, H.; Zheng, G.; Sun, Y.; Li, Y.; Cui, Y.
Nat. Nanotechnol.
2015, 10, 980-985.

[3] Nie, A.; Cheng, Y. C.; Zhu, Y. H.; Asayesh-Ardakani, H.; Tao, R. Z.; Mashayek, F.; Han, Y.; Schwingenschlogl, U.; Klie, R. F.; Vaddiraju, S.
Nano Lett.

2014, 14, 5301-5307.

[4] Nie, A.; Cheng, Y.; Zhu, Y.; Asayesh-Ardakani, H.; Tao, R.; Mashayek, F.; Han, Y.; Schwingenschlögl, U.; Klie, R. F.; Vaddiraju, S.; Shahbazian-Yassar, Reza.
Nano let.

2014, 14, 5301-5307
High Capacity and High Power Ncm/Graphite Lithium Ion Battery Using Microgrid® Expanded Metal Current Collectors
Authors: Hart John
Published: February 2020

To achieve better sustainable power application of LiNi1/3Co1/3Mn1/3O2/graphite lithium ion battery, new cell structures using Microgrid® expanded metal current collectors were studied. By adopting the Microgrid® foil for cathode electrodes, the performance of LiNi1/3Co1/3Mn1/3O2 electrodes was significantly improved at high rate discharge at both room and low temperature. Scanning electron microscopy was carried out to reveal coating features of Microgrid® cathode electrodes. The loading density of active materials can be increased by the pore structure, and the 10C capacity retention of Microgrid® electrode is 25.8% higher than that of a conventional electrode after 100 cycles, and nearly doubled for the initial discharge at 10°C. There is the potential for enhancement of cell performance using Microgrid® foils in place of conventional foils with LiNi1/3Co1/3Mn1/3O2 cathode and graphite anode. The Microgrid® full cell shows 209.0% increase of capacity with respect to conventional cells of Al and Cu foils for 10C after 100 cycles and keeps the retention rate 12% higher than the latter.  Microgrid® foils can potentially be applied to other electrode materials which are suffering from capacity fade at high C-rates and at higher loading densities.