bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of a 30kW SOFC Gas Turbine Hybrid Power Plant
Authors: Henke Moritz , Steilen Mike , Schnegelberger Christian , Riedel Marc , Hohloch Martina , Bücheler Sandro , Herbst Melanie , Huber Andreas , Kallo Josef , Friedrich K. Andreas
Published: February 2020

Hybrid power plants consisting of a gas turbine coupled with solid oxide fuel cells (SOFC) convert chemically bound energy into electrical energy. They can be operated at higher electrical efficiencies than conventional power plants. Theoretical studies suggest electrical efficiencies of up to 70 %.

The German Aerospace Center (DLR) aims to build and operate a hybrid power plant with an electrical power output of 30 kW. The system concept and design of the power plant have been finalized and the specification of all major system components has been carried out. Currently, different system components are being purchased and tested.

The presentation gives an overview of the current status of the project and illustrates the general concept of the power plant. All major components of the power plant are described. Important specifications and characteristics of the components are presented. Results of component tests are presented where available and the expected operating range is specified.
Protonic Conducting Ceramic Hollow Fiber Based on BaCe0.95Tb0.05O3-d
perovskite Membrane for Hydrogen Permeation and MT-SOFC
Authors: Yang Naitao , Meng Xiuxia , Liu Shaomin , Ma Zi-Feng , Tan Xiaoyao , Meng Bo
Published: February 2020

BaCe0.95Tb0.05O3-d (BCTb) thin membranes with perovskite structure were prepared on porous Ni-BCTb hollow fiber by a combined phase inversion with dip-coating technique. After co-sintering at 1500°C, the dense BCTb with a thickness of 15μm is gas-tight, and the N2 permeance of the reduced dual-layer hollow fiber is 3×10−
7 mol·m−
2·s−
1·Pa−
1 at 5 atm. Microtubular solid oxide fuel cell (MT-SOFC) with the configuration of Ag/BCTb/Ni-BCTb possesses high performance. The OCV is reduced with the operation temperature increase from 500 to 800°C,and the variation is significant at 700°C. Meanwhile, the maximum power density is up to 552 mW cm-2 at 700°C, higher than the value at other operation temperature increase. These imply that the serious electron leakage occurs above 700°C, and thus the Hydrogen permeation was carried out. The hydrogen permeation flux is as high as 0.61mLmin-1 cm-2at 850°C.
The Promise and Challenges of Intermediate Temperature Fuel Cells
Authors: Litzelman Scott Joseph , Lemmon John Patrick
Published: February 2020

Fuel cell systems span a wide range of temperatures, materials, and type of ionic transport. An intermediate temperature range of 200 to 500 degrees Celsius has received less attention than higher and lower temperature fuel cell systems due to the relatively few number of electrolytes that operate in this range. However materials research over the past 15 years has resulted in new electrolytes with sufficiently high ionic conductivity to enable intermediate temperature fuel cells (ITFCs). The focus of the Reliable Electricity Based on ELectrochemical Systems (REBELS) program at the U.S. Department of Energy Advanced Research Projects Agency-Energy (ARPA-E) is to create ITFCs with the potential for drastically reduced system costs, as well as enhanced electrochemical functionality such as rapid response to transients and electrochemical production of liquid fuels. Compared to lower temperature polymer electrolyte membrane (PEM) fuel cells, little or no precious metal catalysts are required for sufficient electrode kinetics. The higher temperatures also increase fuel flexibility and tolerance to impurities. Compared to higher temperature solid oxide fuel cells (SOFCs), a range of less expensive interconnects and seals are available and the system can be operated in more of a load-following manner. In addition to these ITFC benefits, challenges will be identified and discussed particularly with respect to higher temperature SOFCs. These challenges include methane reforming, ohmic resistance of the electrolyte, and electrode overpotentials at reduced temperatures. Potential pathways to overcome these challenges will be proposed and examples of the new concepts under development in the REBELS program will be highlighted.
Life Time Performance Characterization of Solid Oxide Electrolysis Cells for Hydrogen Production
Authors: Sun Xiufu , Chen Ming , Liu Yi-Lin , Hendriksen Peter Vang
Published: February 2020

Globally the amount of electricity generated from renewable energy sources such as wind or solar energy is increasing. To integrate high amount of fluctuating renewable energy into the existing energy grid, efficient and cost competitive conversion of electricity into other kinds of energy carriers is needed. Solid oxide electrolysis cells (SOECs) offer a promising technological solution for efficient energy conversion and production of hydrogen or syngas (mixture of H2 and CO) using excess electricity from renewable energy sources. For SOECs to become commercially interesting, performance, durability, and cost are among the most critical issues. Long-term stable performance over 5-10 years of operation is generally required. The commercialization of the SOEC technology can be further promoted if SOECs can be operated at high current density, as it helps reducing electrolyser capacity cost significantly. In this work, long-term durability of Ni/yttria stabilized zirconia (YSZ) supported planar SOECs were investigated at 800 oC for electrolysis of steam. The cells, which represent the state-of-the-art SOEC technology at Technical University of Denmark (DTU), have a Ni/YSZ support and active fuel electrode, a YSZ electrolyte, a gadolinia doped ceria (CGO) barrier layer and a LSCF/CGO (LSCF: strontium and cobalt co-doped lanthanum ferrite) composite oxygen electrode. The cells were exposed to long-term galvanostatic electrolysis tests at different current densities from 0 (i.e. under open circuit voltage, OCV) to -1.25 A/cm2. Detailed electrochemical and post-mortem characterizations were further conducted in order to clarify the cell or electrode degradation mechanisms. The cells show stable performance, with a steady-state degradation rate of up to 2 %/1000 h for electrolysis tests with current densities up to -1 A/cm2. The long-term degradation is dominated by increase in serial resistance, which can be associated to a great extent with microstructure changes in the active Ni/YSZ electrode, namely Ni loss (directly reflected by an increase in the porosity) and Ni re-distribution. Operating the cells at -1.25 A/cm2 causes severe and accelerated degradation, which is associated with both the Ni/YSZ fuel electrode and the LSCF/CGO oxygen electrode. Assuming an end-of-life cell voltage of 1.5 V, the cell life time is then predicted as a function of electrolysis current density. The current generation SOEC cells produced at DTU are able to be operated at current density up to ~-0.9 A/cm2, in order to achieve a commercialization target of 5 years lifetime (for continuous electrolysis operation of hydrogen production). The cells can be operated at even higher current density, if the hydrogen production is intermittent. The results of the current work provide valuable technological inputs to future design of electrolysis plants for hydrogen production.
Electrochemical Synthesis of Ammonia with Proton Conducting Solid Electrolyte Fuel Cells at Intermediate Temperatures
Authors: Otomo Junichiro , Noda Naoto , Kosaka Fumihiko
Published: February 2020

Electrochemical synthesis of ammonia with solid electrolyte fuel cells using proton conducting solid electrolyte such as barium cerate was investigated at intermediate temperature of around 773 K. Electrode catalysts of metal alloys and mixed conductors including metals of Pd and Ru as active sites were synthesized. Two-electrode configuration was employed with dynamic hydrogen electrode (DHE) for CE, i.e., WE(N2)|solid electrolyte|CE(H2). It was observed that ammonia formed on the working electrode (WE) through the reaction of nitrogen with proton diffusing from the counter electrode (CE). The production rate of ammonia was influenced by electrode potential and it showed the maximum at around -300~-500 mV for both of Pd and Ru-based electrodes. Ru-based catalyst that might promote nitrogen bond dissociation showed good performance on ammonia formation. The electrode optimization was also discussed in terms of conduction paths of proton and electron in the electrodes.
Reversible Type Solid Oxide Fuel Cells Using Ni-Fe-CeO2 Based Cermet Fuel Electrode and Applied for Metal-Air Rechargeable Battery
Authors: Ishihara Tatsumi , Inoishi Atsushi , Kim Hackho , Ida Shintaro
Published: February 2020

Solid Oxide Fuel Cells (SOFC) is expecting as a highly efficient energy convertor.  On the other hand, recently, there are strong interests on high temperature steam electrolysis because of efficient hydrogen production method.   In addition, reversible operation of SOFCs is also interesting as an energy storage method. Therefore, recently, there is also high interest on reversible operation type SOFC so-called SORC.  At present, for SORC, similar materials for conventional SOFC are widely used, i.e., Y2O3 stabilized ZrO2 and Ni based cermet for electrolyte and fuel electrode, respectively.  However, because of high temperature operation, energy efficiency as well as stability is still not high as an energy storage process.  

   In this study, we investigated intermediate temperature SORC using LaGaO3 electrolyte. For reversible type operation, aggregation of Ni is easily occurred but it was found that addition of small amount of Fe is effective for preventing aggregation of Ni.  The optimized composition for fuel electrode is Ni-Fe(9:1) from stability.   Effects of mixed conducting oxide added for Ni-Fe were studied.  For SOFC operation, power density is larger as the following order, Ce(Mn,Fe)O2<NiFe=La(Sr)Ga(Mg)O 3<Ce0.8Sm0.2O2< La(Sr)Fe(Mn)O3. On the other hand, for SOFC operation, the electrolysis current density is increased as the following order,  Ce(Mn,Fe)O2<NiFe<La(Sr)Ga(Mg)O3<< La(Sr)Fe(Mn)O3 <Ce0.8Sm0.2O2.  Therefore, for reversible operation, NiFe-SDC shows the most active.   Degradation of the cell using NiFe-SDC and Sm(Sr)CoO3 for fuel and air electrode, respectively, was studied at 1073 K, 100mA/cm2.  The observed terminal potential was 1.13 and 1.025 V for SOEC and SOFC respectively at initial cycle and the observed potential slightly increased for SOFC and decreased for SOEC with cycle number, however, after 50 cycles, the observed terminal potential was 1.15 and 1.0 V for SOFC and SOFC, respectively.   Therefore, the degradation is hardly observed for the reversible operation of the cell. 

Combination of SORC with metal oxidation could open a new application area for fuel cell. In this study, application of various metals like Fe, Sn, Al, and Mg to SORC were studied by using CaO Stabilized ZrO2 for electrolyte  and it became clear that redox of metal proceeded in SORC electrochemically resulting in the all solid state metal-air rechargeable battery.  The observed open circuit potential is well agreed with theoretical PO2 from Gibbs free energy of metal oxidation.  By decreasing operating temperature, PO2 range of electrolyte domain can be expanded.  Application of LSGM for electrolyte of this new concept of oxygen redox shuttle battery will also be discussed.
Catalytic Total Oxidation of SOFC Exhaust Gas on Cu-Mn Catalysts
Authors: Sung Jae Gi , Song Ki Hun , Chung Jong Shik , Sammes Nigel Mark
Published: February 2020

SOFC exhaust gases, such as methane and carbon monoxide, cause environmental problems. However, extra energy can be realized from oxidizing these out-gases into CO
2
and H
2
O. This extra energy can be recycled in an SOFC system and increase the thermal efficiency. Thus the development of new catalysts that lower the oxidation temperature will make the SOFC system more efficient.

           CULLEN et. al.[1] reported high conversion rate of SOFC exhaust gas using a La-Cu-Mn impregnated alumina catalyst and a Pt-Pd catalyst in series. In this work, Cu-Mn catalysts that are used in the oxidation of methane or carbon monoxide were tested for SOFC exhaust gas oxidation.

           For determining the best ratio of Cu-Mn in catalysts, different ratios of La2O3-MnO-CuO/γ-Al2O3catalysts were prepared. The result shows approximtely 0.5 to 2 Cu/Mn ratio is the best composition for SOFC exhaust gas oxidation[Fig. 1].

Fig. 1. Conversion of CO(160℃), H2(240℃), CH4(460℃) with various Cu-Mn ratio.

           Cu-Mn perovskite and spinel supported catalysts were also tested. The perovskite supported catalysts showed much higher activity than the spinel supported. This was especially so for the case of methane conversion; the perovskite supported catalysts showed similar performance to alumina supported. The methane conversion of reference, CP and MP were 53.1%, 55.1% and 56.3% at 500℃, respectively.

References

[1] Greg CULLEN, Jon P. Wagner, Georg Anfang, Chandra Ratnasamy, METHOD FOR REMOVING CO, H2 AND CH4 FROM AN ANODE WASTE GAS OF A FUEL CELL AND CATALYST SYSTEM USEFUL FOR REMOVING THESE GASES, US 2012/0128563 Al, 2012

Figure 1
Thermal Performance of Brazed Plate Heat Exchanger in High Temperature Applications
Authors: Lo Huai Po
Published: February 2020

This study examines the performance of brazed plate heat exchanger (BPHE) in an experimental air loop. The high temperature experimental system used for testing the heat transfer and pressure drop for simulation exhaust gas applicable for SOFC system is developed. The inlet temperature and mass flow rate were varied from 300 to 700 °C /0.0015~0.0041kg/s in the hot side to simulate high temperature exhaust gas and 25°C /0.0013~0.005 kg/s in the cold side. A total of  three tests are conducted (Test1: Th=300~700°C, Tc=25 °C, mh=0.0041kg/s, mc=0.005kg/s; Test 2: Th=700°C, Tc=25 °C, mh=0.0034kg/s, mc=0.0013~0.005kg/s; Test 3: Th=700°C, Tc=25 °C, mh=0.0015~0.0041kg/s,  mc=0.005kg/s;). The experimental results showed that the effect of inlet mass flow rate on the temperature performance is quite significant, and the heat transfer coefficient and pressure drop are related to the mass flow rate.
Fabrication of SmBa0.5Sr0.5Co2O5+δ
Cathode Material and Its Application for Sr- and Mg-Doped LaGaO3 Electrolyte-Supported Solid Oxide Fuel Cell
Authors: Lin Tai-Nan , Lee Ruey-Yi , Kuo Jen-Yuan , Ishihara Tatsumi , Hosoi Kohei
Published: February 2020

The layered samarium and strontium doped perovskite oxide SmBa0.5Sr0.5Co2O5+

δ 
(SBSC) was synthesized by glycine nitrate combustion process (GNC). The structure, microstructure, conductivity, coefficient of thermal expansion properties were investigated. The crystallinity of SBSC powder showed pure perovskite phase above 1000 °C according to the XRD and TGA results. With the calcination temperature increased, the crystallinity improved and the powders grew larger and agglomeration occurred. The conductivity of SBSC powders increased with elevated temperature while the coefficient of thermal expansion was 22.6 × 10-6 K-1. SBSC powders were utilized as cathode materials in Sr- and Mg-doped LaGaO3 (LSGM)-based electrolyte-supported solid oxide fuel cell for power performance test. The cell with structure of (NiFe + CMF) | LSGM | SBSC was operated from 700 to 800 °C with humidified H2 as a fuel and ambient air as oxidant. The maximum power densities are 550 and 170 mW cm-2
at 800 and 700 °C, respectively. The experimental results indicate that SBSC is a promising cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC).
Ln2NiO4+δ
(Ln = La, Pr) As Suitable Cathodes for Metal Supported Cells
Authors: Rougier Aline D. , Flura Aurélien , Nicollet Clément , Vibhu Vaibhav , Fourcade Sébastien , Lebraud Eric , Bassat Jean-Marc , Grenier Jean-Claude
Published: February 2020

In the last decade, thanks to their mixed ionic and electronic conductivity (i.e. MIEC properties), the lanthanide nickelates, Ln2NiO4+
δ (Ln = La, Pr, Nd) have attracted much attention as cathode for solid oxide fuel cells. Simultaneously, Metal Supported Cells (MSCs) for IT-SOFC application (typically 600 – 700 °C) have been developed in respect of several advantages including reduced cost and better thermal cycling resistivity. Nevertheless, the use of porous metal implies to sinter the constitutive elements of the cells under low pO2 (e.g. under N2, pO2 » 10-4 atm). In that respect, the chemical stability, thermal and chemical expansion when exposed to temperatures as high as 1400 °C, under pO2 as low as 10-4 atm of Ln2NiO4+
δ
phases were studied through TGA (Thermal Gravimetry Analysis), XRD analyses, high temperature X-ray diffraction and Thermal Expansion Coefficient measurements. 

Electrochemical Impedance Spectroscopy measurements on Ln2NiO4+
δ//GDC//YSZ symmetrical half-cells sintered either in air or under argon at various temperatures have been performed in the range 500 °C to 800 °C, in air, at idc = 0 A. Pr2NiO4+δ, either sintered in air or under nitrogen at 1150 °C and then re-oxidized, shows the lowest polarization resistance values (Rp = 0.12 Ω.cm2 at 600 °C) while La2NiO4+δexhibits smaller polarization resistances when sintered under nitrogen, compared to air. Finally, the suitability of lanthanide nickelates in MSCs will be demonstrated and the relationship between cathode performances and structural and microstructural features will be discussed in details. Besides,modelling of the impedance data will be emphasized.
PrBaCo2O6-δ
- Ce0.8Sm0.2O1.9 Composite Cathodes for Intermediate Temperature Solid Oxide Fuel Cells
Authors: Tsvetkov Dmitry S. , Tsvetkova Nadezhda S. , Ivanov Ivan L. , Malyshkin Dmitry , Sereda Vladimir V. , Zuev Andrey Yu.
Published: February 2020

The single phase double perovskite PrBaCo2O6-δ and composites (100-y) PrBaCo2O6-δ - y Ce0.8Sm0.2O1.9 (y = 10 - 30 wt.%) were investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). The chemical compatibility, thermal expansion behavior, DC conductivity and electrochemical performance of these materials were studied. The results on chemical compatibility showed no reaction between PrBaCo2O6-δ and Ce0.8Sm0.2O1.9 electrolyte even at temperature as high as 1200 °C. The average thermal expansion coefficient and overall conductivity of (100-y) PrBaCo2O6-δ - y Ce0.8Sm0.2O1.9 (y = 10 - 30 wt.%) composite materials were shown to decrease with increasing content of Ce0.8Sm0.2O1.9 in the composite whereas the polarization resistance was found to increase somewhat at the same time. Although the thermal expansion coefficient of the composite cathodes remains too high as compared to that of the electrolyte, the values of their total conductivity and electrochemical activity meet requirements for successful application of such cathode materials in IT-SOFCs.
Electrical Conducting Properties of LSF-Based Composites as an Interconnection of Tubular Type of Solid Oxide Fuel Cells
Authors: Yu Ji Haeng , Lee Hee Lak , Shin Hyung Chul , Cho Sangyoung , Joo Jong Hoon , Yoo Chung-Yul
Published: February 2020

Tubular type of solid oxide fuel cells (SOFCs) is durable under high temperature operation compared to planar type SOFCs where the use of metallic interconnect is inevitable, which deteriorate electrochemical performance by Cr evaporation. On the contrary, development of ceramic interconnection has been a hurdle to fabricate tubular type SOFCs. The ceramic interconnection material must have high electronic conductivity both in oxidizing and reducing atmosphere. A gas-tight microstructure should also be obtained mostly by co-firing with anode or cathode substrates. We have been developing flat-tubular SOFCs from extruded NiO-YSZ tubular substrates. In this study we investigated (La,Sr)FeO3 (LSF)-based composite materials as the interconnection for tubular SOFCs. La0.8Sr0.2FeO3-δ, a mixed ionic and electronic conductor, was mixed with Gd- or La-doped ceria (GDC or LDC). LSF is a mixed ionic and electronic (hole) conducting material and thus shows low electrical conductivity in reducing (H2) atmosphere. However, composite materials with LSF and ceria showed moderate electrical conductivity by electronic leakage current through doped ceria in reducing atmosphere. LSF-ceria composite and LSF layers were also successfully deposited on NiO-YSZ anode substrate by conventional co-firing process. The area specific resistance of LSF/LSF-GDC bilayer on Ni-YSZ measured in air//H2 condition was initially ~50 mΩ cm2.
Novel Dilithium Metal Oxyfluoride As High Capacity Intercalation Cathode Material for Li-Ion Batteries
Authors: Ren Shuhua , Chen Ruiyong , Hahn Horst , Fichtner Maximilian
Published: February 2020

Lithium-ion batteries (LIBs) have transformed portable electronics and will play a key role in transport applications. However, the highest energy storage in the existing LIBs is insufficient for the long-term needs of society [1-2]. Good structural stability and minimal volume change over the entire operational Li insertion/extraction voltage range is preferable for LIBs to achieve good cell performance. The discovery and synthesis of new lithium intercalation materials with stable crystal structure and significantly improved energy density are urgently required.

Recently, we developed a new disordered dilithium metal oxyfluoride of Li2VO2F [3-4]. The novel material exhibits outstandingly high capacity of 420 mAh g-1 with small lattice change of only 3% owing to its stable rock-salt host structure. Lithium, occupying 2/3 of the cation sites, is highly mobile [5-6]. Compared to the redox of V3+/5+ at ~2.5 V, the chromium substitution into Li2VO2F leads to increased discharge voltages (accordingly higher energy density) and better cyclic stability. Moreover, nearly 1.8 Li+are accessible and can be reversibly stored at a current rate of ~ C/35 and room temperature [7]. Various characterization techniques were applied to verify the redox process and reversible structural change upon electrochemical cycling. The novel dilithium oxyfluoride intercalation material with disordered rock-salt structure opens new possibilities for obtaining higher storage capabilities for LIBs.

References:

P. G. Bruce, B. Scrosati, J.-M. Tarascon, Angew. Chem. Int. Ed., 2008, 47, 2930.

M. S. Whitthingham, Chem. Rev., 2004, 104, 4271.

R. Chen, S. Ren, S. Indris, M. Fichtner, H. Hahn, EP 14160894.3, 2014.

R. Chen, S. Ren, M. Knapp, D. Wang, R. Witter, M. Fichtner, H. Hahn, Adv. Energy Mater., 2015, DOI: 10.1002/aenm.201401814.

J. Lee, A. Urban, X. Li, D. Su, G. Hautier, G. Ceder, Science, 2014, 343, 519.

A. Urban, J. Lee and G. Ceder, Adv.
Energy Mater., 2014, 4, 1400478.

S. Ren, R. Chen, E. Maawad, O. Dolotko, A. A. Guda, D. Wang, H. Hahn, M. Fichtner, to be submitted.
Viability of MCM-41 Inorganic Membrane Separator in Secondary Nickel-Zinc Cell
Authors: Meskon Shahrul Razi , Othman Raihan , Ani Mohd Hanafi
Published: February 2020

The viability of MCM-41 inorganic membrane as a separator material in secondary nickel-zinc cell is investigated. MCM-41 mesoporous material consists of arrays of hexagonal nano-channels. The membrane is synthesized by dip-coating procedures from parent solution comprising of quarternary ammonium surfactant, cethyltrimethylammonium bromide C16H33(CH3)3NBr (CTAB), hydrochloric acid (HCl), deionized water (H2O), ethanol (C2H5OH), and tetraethylortosilicate (TEOS). Both the anodic zinc foil and cathodic nickel hydroxide electrodeposited film are coated with MCM-41 membrane. The Ni/MCM-41/Zn alkaline cell is then subjected to 100-cycle durability test. The charge-discharge plot showed typical secondary zinc anode profile – rapid capacity fading. X-ray diffraction analysis on the dismantled cell indicated the transformation of MCM-41 hexagonal matrix structure into MCM-50 lamellar gel form which prevent the mesoporous cell separator from diminished in the caustic alkaline surround.
Core/Shell Si-Ni/C Anodes for High-Energy-Density Li-Ion Batteries
Authors: Goldshtein Keren , Goor Meital , Freedman Kathrin , Golodnitsky Diana , Peled Emanuel
Published: February 2020

The goal of this research was the development of low-cost, high-capacity, long-cycle-life and safer anode materials to replace the graphite anode of the common lithium-ion battery. Silicon offers the highest gravimetric capacity as an anode material (e.g. Li22Si5: nearly 4,200mAh/g). However, Si-based electrodes typically suffer from large volume changes (up to 420%) during insertion and extraction of lithium. This is followed by cracking and pulverization of silicon, which in turn, leads to the loss of electrical contact, an unstable SEI and eventual capacity fading.

Our strategy for reducing the deterioration of silicon involve attaching silicon and silicon-nickel nanoparticles to multiwall carbon nanotubes (MWCNT) in order to create a silicon-based active anode material supported by a strong, rigid and high-electrically-conducting network. The method is based on the pyrolysis of the mixture of nanoparticles and nanotubes with carbon precursor. Silicon-nickel alloying is achieved by electroless or grinding process followed by pyrolysis. Nickel was chosen since, when alloyed with silicon, this metal is expected to stabilize the structure of lithiated silicon nanoparticles, increase electron conductivity and possibly induce graphitization of the carbon shell.

Li/SiNi-MWCNT-C (1.6mg/cm2 loading) cells exhibited a de-intercalation capacity of 900mAh/ganode at C/7, 600mAh/ganode at C/3.4 and 400mAh/ganode at C/1.7. Irreversible capacity of 22% and high faradaic efficiency (FE) of 99.5% were obtained. Very highly loaded anodes, weighing 5.5mg/cm2, with de-intercalation capacities of 1000mAh/ganode, demonstrated stable cycle life three times greater than that of graphite.
Study and Development of Al-Air Battery Applying Room Temperature Ionic Liquid Electrolyte
Authors: Gelman Danny , Shvartsev Boris , Wallwater Itamar , Ein-Eli Yair
Published: February 2020

Metal – air battery chemistry defers by the electrolyte of choice. Zn – Air, Al – Air and Fe – Air batteries were already reported utilizing aqueous alkaline and brine solutions as electrolytes. The main advantage of these specific electrolyte of choice is theirs high ionic conductivity and the ability to efficiently reduce oxygen into hydroxide anions. Nevertheless, such batteries systems suffers from major drawbacks, such as comparably low voltage and specific energy, for Zn and Fe, and extremely high corrosion rates under open circuit condition, for Al.

To deal with such challenges a fairly new approach has been taken. The approach is based on Room Temperature Ionic Liquids (RTIL) utilization as electrolyte in Metal – air batteries research. Among these, one could find Na –and Si – air battery systems. RTILs offer unique properties, while serving as electrolytic media. Among the properties one can count their low vapor pressure, even at considerably elevated temperatures, the high intrinsic ionic conductivity, non-flammability, thermal and chemical stability with considerably large electrochemical windows (in some cases as much as 5 V) what makes them remarkable electrolytes for high-end  electrochemical applications. In our recent report[1], a new Al – air battery was presented applying 1-ethyl-3-methylimidazolium oligoflourohydrogenat (EMIm(HF)2.3F) RTIL. The specific conductivity of this exact stoichiometry is 100 mS cm-1 at 298 K, one the highest of all RTIL family, comparable to that of 0.5 M KCl aqueous solution. The presented novel Al – air battery can sustain current densities up to 1.5 mA cm-2, producing capacities above 140 mA h cm-2, and thus utilizing above 70% of the theoretical Al capacity. This is equivalent to outstanding energy densities of 2300 W h kg-1 and 6200 W h L-1.

In the current work a further investigation of the RTIL based Al – air battery is presented. Combining surface characterization with electrochemical experiments, both in half cell and also a full battery discharge, an ongoing progress in the study of this unique battery is shown. One of the main achievements in the study is related to the understanding of the operation voltage drop (deep). Conditions for elimination of this voltage deep were established and will be reported.

   

[1] D. Gelman, B. Shvartsev, Y. Ein-Eli, J. Mater. Chem. A. 2.47 (2014) 20237-20242.
Comparison of Amorphous TiO2 with Anatase Thin-Films Grown By ALD in Terms of Rate Performance and Capacity for Li+-Insertion
Authors: Moitzheim Sebastien , Deng Shaoren , Detavernier Christophe , De Gendt Stefan , Vereecken Philippe M
Published: February 2020

In this work we compare amorphous TiO2 to anatase thin-films for their Li+ insertion/extraction properties. For this, we deposited ultra-thin (35 nm) amorphous TiO2  and anatase films by atomic layer deposition on a TiN current collector. Such thin films are interesting since they have the same length scale as nanostructured particles or other nanostructures, e.g. nanotubes, but with the additional benefit of offering a well-defined geometry that allows for a more precise determination of the underlying lithium insertion/extraction kinetics. Furthermore, such ultra-thin electrodes might find application in 3D (micro-)batteries.

The amorphous and anatase films were characterized using cyclic voltammetry and galvanostatic charging/discharging. The electrochemical properties of 35 nm amorphous TiO2 and anatase films are shown in figure 1. The cyclic voltammograms (CV, see figure 1a) performed at 10 mV/s shows distinction between lithium insertion/extraction of the amorphous and anatase films. The average of the insertion and extraction peak potentials is 1.65 V vs Li+/Li and 1.99 V vs Li+/Li for amorphous and anatase, respectively.  Also, the peaks in the CV for amorphous TiO2 are less sharp compared to anatase, suggesting a different intercalation mechanism.

Galvanostatic charge/discharge experiments show a significantly increased capacity for amorphous compared to anatase (see figure 1b). At 1C, the amorphous TiO2 film has a capacity of 1.9 µAh/cm2 compared to 1.2 µAh/cm2 for the anatase film. Also, at higher C-rates the amorphous TiO2 film shows high retention of the capacity. For example, at 20C, 63% of the capacity at 1C is retained, compared to 30% for anatase. These results show the potential benefits of using amorphous TiO2 compared to anatase thin-films due to its significantly higher capacity and superior rate performance.

Figure 1
Electrochemical Studies of Vanadium-Based Polyoxometalate Molecular-Cluster Batteries
Authors: Chen Han-Yi , Friedl Jochen , Al-Oweini Rami , Pan Chun-Jern , Hwang Bing-Joe , Kortz Ulrich , Srinivasan Madhavi , Stimming Ulrich
Published: February 2020

The lithium ion battery (LIB) is a promising energy storage technology for electric vehicles [1]. The most commonly used cathode material in LIBs is LiCoO2. Lithium ion intercalation/de-intercalation into the layer-structured LixCoO2 can result in fast capacity fading. Besides, the kinetic rate of lithium ion intercalation/de-intercalation in the lattice structure is slow which causes low power density.[2] Polyoxometalates (POMs) are transition metal oxide molecular clusters with various structures and have been reported as promising cathode active material for energy storage applications. Due to their multiple redox centers they can undergo fast and reversible redox reactions.[3-5] POMs are expected to undergo redox process as a molecular cluster, thus the stability of the POMs is not depended on the recoverability of its long-term crystal structure. The most commonly used POMs in Li ion Molecular-Cluster Batteries (MCBs) are Mo-based POMs which can achieve a capacity of 270 mAh g-1. However, the cycling stability of Mo-based POMs is poor because of the instability of molecular cluster ions [PMo12O40]3- in the reduced state and high solubility in the electrolytes. Vanadium based POMs have been reported to possess a high capacity of up to 200 mAh g-1, and higher cycling stability than Mo-based POMs. However, the valence and fine structural changes of V-based POMs MBCs during charging/discharging have not yet been investigated. Thus, we performed in-situ V K-edge XAFS measurements for V-based POM molecular cluster batteries, and determined the oxidation states and inner structure changes of V-based POM during charging/discharging. Furthermore, the kinetic studies of V-based POM MCBs were also performed by chronoamperometry experiments in this research.

[1]  H. Wang, S. Hamanaka, T. Yokoyama, H. Yoshikawa, K. Awaga, Chemistry-an Asian Journal 2011, 6, 1074.

[2]  H. Wang, S. Hamanaka, T. Yokoyama, H. Yoshikawa, K. Awaga, Chemistry-an Asian Journal 2011, 6, 1074.

[3]  N. Kawasaki, H. Wang, R. Nakanishi, S. Hamanaka, R. Kitaura, H. Shinohara, T. Yokoyama, H. Yoshikawa, K. Awaga, Angewandte Chemie-International Edition 2011, 50, 3471.

[4]  H. Wang, S. Hamanaka, Y. Nishimoto, S. Irle, T. Yokoyama, H. Yoshikawa, K. Awaga, Journal of the American Chemical Society 2012, 134, 4918.

[5]  E. Ni, T. Kume, S. Uematsu, Z. Quan, N. Sonoyama, Electrochemistry 2014, 82, 14.
Synthesis and Characterization of Nitrogen-Doped Reduced Graphene Oxides for the Oxygen Reduction Reaction in the Zn-Air Batteries
Authors: Hu Chi-Chang , Wu Sheng-Hui , Li Po-Chieh
Published: February 2020

The electron transfer number of the oxygen reduction reaction (ORR) on the nitrogen-doped reduced graphene oxide (N-rGO) has been controlled using the experimental design strategy which includes the studies of the fractional factorial design and the paths of the steepest ascent/descent. For the applications in the zinc-air batteries and alkaline fuel cells, the electron transfer number approaching 4 is desirable; i.e., rendering the ORR to undergo the four-electron transfer mechanism. The maximum electron transfer number of the ORR is 3.9 on our N-rGO prepared in this work. The structure and distribution of nitrogen doped onto the rGO have been measured by the x-ray photoelectron spectroscopic analysis. The N-rGO with the electron transfer number of the ORR close to 4 is employed in the aqueous Zn-air batteries. The typical discharge behavior of the zinc-air battery with an air cathode using N-rGO in 6 M KOH at 2, 10, and 20 mA cm-2 was examined in this work. The corresponding discharge curves of the Zn anode and air cathode were measured to investigate their individual performances. The discharge capacity of the above full cell test is above 775 mAh g-1 (based on the zinc mass) which is very close to the theoretical value (820 mAh g-1).
Analysis of Graphene Coating on Si Anode and Defect Engineering for Lithium Ion Battery
Authors: Yi Sangkoan , Moon Janghyuk , Cho Maenghyo , Cho Kyeongjae
Published: February 2020

Silicon is the most promising anode material due to its huge capacity about 4200mAh/g and their abundance. However its usage is hindered by large volume expansion, causing pulverization and so on. To reduce the problems, coating on silicon anode is one of the efficiency methods. In this presentation, computational study on the effect of graphene coating to Si anode material is performed by using density functional theory calculations. We construct the atomic model to examine interactions between amorphous silicon and graphene during lithiation. The lithiation of Si anode increases the not only mechanical contact force between outer graphene layer and amorphous silicon but also the shear resistance. To explain the interaction between graphene and silicon, we examine the charge distribution of silicon and graphene considering lithiation insertion. The number of density, electron field distribution and electric potential are also calculated. Charge-non polar interaction between Li-ion and graphene increase the contact energy between graphene-silicon. In addition, we also study the effect of defect on graphene such as mono, di, and stone-wales defect. These defects increase the contact force between defected graphene and lithium silicide.
Inhibition of Polysulfides Dissolution and Shuttling By Solid Electrolyte and Macro-Structural Cathode for Lithium-Sulfur Batteries
Authors: Liu Jin , Zhang Cheng , Lin Yue , Liu Yexiang
Published: February 2020

Lithium-sulfur batteries possess high theoretical capacity of 1672 mAh/g. However, polysulfides dissolution and shuttling will cause loss of sulfur active materials, leading to fast capacity decay of batteries. Here, a few methods for locking sulfur by solid electrolyte and macro-structural cathode are introduced. The all-solid-state lithium-sulfur batteries can deliver the discharge capacity of 601 mAh/g at 4 C and 80 oC. Even over 1000 cycles, stable discharge capacities with an average capacity loss of 0.31 mAh/g per cycle are obtained. Mechanisms for such enhancement are investigated by cyclic voltammetry, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and thermo-gravimetric analysis techniques. Studies show that polysulfides dissolution and shuttling are obviously inhibited by this system. Such all-solid-state lithium-sulfur batteries are promising power sources for electric vehicles and energy storage stations.Lithium-sulfur batteries possess high theoretical capacity of 1672 mAh/g. However, polysulfides dissolution and shuttling will cause loss of sulfur active materials, leading to fast capacity decay of batteries. Here, a few methods for locking sulfur by solid electrolyte and macro-structural cathode are introduced. The all-solid-state lithium-sulfur batteries can deliver the discharge capacity of 601 mAh/g at 4 C and 80 oC. Even over 1000 cycles, stable discharge capacities with an average capacity loss of 0.31 mAh/g per cycle are obtained. Mechanisms for such enhancement are investigated by cyclic voltammetry, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and thermo-gravimetric analysis techniques. Studies show that polysulfides dissolution and shuttling are obviously inhibited by this system. Such all-solid-state lithium-sulfur batteries are promising power sources for electric vehicles and energy storage stations.
Oxygen Reduction in Si-Air Battery Employing MnO2 Catalyst - a Phenomenological Thermodynamic Analysis
Authors: Harinipriya S , Sangaranarayanan M.V.
Published: February 2020

The steps involved in Oxygen Reduction Reaction (ORR) mechanism are as follows:

Step (i) : Diffusion of molecular oxygen on MnO2 catalyst

Step (ii): Chemisorption of molecular oxygen at MnO2 surface

Step (iii): Dissociation of molecular oxygen on MnO2 surface

Step (iv): Reduction of molecular oxygen on MnO2 surface and reduction of MnO2 (Mn(IV)) to Mn2O3 (Mn(III))

Step (v): Diffusion of oxygen anion on the MnO2 surface

Step (vi): Incorporation of oxygen in MnO2 lattice at the oxygen vacant site

Assumptions :

(i) maintenance of electroneutrality

(ii) VO (surface) >> VO(bulk) of MnO2 lattice

(iii) electrons for oxygen reduction and reduction of Mn4+ to Mn3+ comes from anodic reaction

(iv) effects due to formation of MnF2 during discharge of Si-air battery is neglected.

(v) wherever partial bonds are formed or dissociated, the bond energy is averaged over the coordination number or total number of vacant sites as the case may be

(vi) the pressure of oxygen gas is written using the van der Waals equation

of state

Derived Equation can now be utilized to estimate the free energy of activation for ORR mechanism in Si – air battery and engineer catalysts suitable for fast ORR in these batteries.
Electrode Calendering Optimization
Authors: Gonzalez Daniel , Rubio Irene , Beattie Shane D
Published: February 2020

Among commercially available batteries Li-ion has one of the highest volumetric energy densities. A critical step that manufacturers use to maximize volumetric energy density is to calender electrodes after coating to reduce thickness and increase density. Although optimal calendering parameters are well known to industry, useful information in the literature is scarce, and systematic studies are difficult to find.  This dissertation will provide a methodical study of electrochemical performance as a function of calendaring properties.

Graphite electrodes were calendered at different temperatures (room temperature to 120 oC) with different nip openings (40 to 100 μm). Electrode density is correlated with electrochemical performance using data from coin cell hardware.  Results show that the highest amount of calendaring does not necessarily result in the largest volumetric energy density. This may be due to excessive porosity reduction, which prevents the electrolyte from wetting all of the electrode particles.
Synthesis and Performance of Disordered Positive Electrode Materials for Lithium Ion Batteries
Authors: Glazier Stephen , Dahn Jeff R
Published: February 2020

Disordered rocksalt materials of the form Li1+xMy(1-x)N(1-y)(1-x)O2have been largely overlooked as a potential candidate for high performance positive electrode materials in lithium ion batteries due to the inability of lithium to percolate through the disordered structure.  Recent works [1, 2] have shown these materials are able to form percolation networks if sufficient lithium and cation mixing is present in the structure. As these materials become more lithium rich, the probability of finding a network of favourable Li channels increases. However, for many transition metal choices for M and N the available redox capacity decreases. This must be considered in order to design compositions for optimal performance.

This work explores these recent theories and looks to improve the design and understanding of disordered materials. Many elemental combination series are synthesized between x = 0.00 to 0.33 in Li1+xMy(1-x)N(1-y)(1-x)O2 using solid state synthesis methods with varying temperature and excess Li content to explore the role of synthesis in disordering. Choices for M and N include V, Ti, Mn, Fe, Mo, and Cr in order to investigate capacity relationships due to available redox and Li channels.  Materials are characterized by X-Ray Diffraction (XRD), in-situ and ex-situ XRD, scanning electron microscopy, Mossbauer spectroscopy, induced coupled plasma optical emission spectroscopy and electrochemical testing. The structural and electrochemical data is compared with theoretical models based on available redox capacity and percolation theory.

Figure 1 shows that synthesis temperature plays an important role in the disordering process. Figure 2 demonstrates a series of Li1+xTiy(1-x)Fe(1-y)(1-x)O2 (0.00 ≤ x ≤ 0.25) heated at 800 °C. Electrochemical results were found to agree with current and proposed theories of disordered materials.

Discussion will include the importance of synthesis in disordered materials, as well as the performance of select series and how they compare to theoretical models.

References:

1.  A. Urban, J. Lee, G. Ceder, Adv. Energy Mater.,
4 1400478 (2014)

2.  J. Lee, A. Urban, X. Li, D. Su, G. Hautier, G. Ceder, Science, 343 519-522 (2014)

Figure 1
Characterization and Optimization of the Carbon Nanocoatings Onto LiFePO4 Particles for Lithium-Ion Batteries
Authors: Swider Joanna , Molenda Marcin , Dziembaj Roman
Published: February 2020

Lithium iron phosphate (LiFePO4, LFP), among the various materials under development for use as cathodes in lithium-ion batteries, has been so far studied and considered as the most promising candidate for this application. Olivine-structured LiFePO4 has been first reported by Pahdi et. al. in 1997 [1] and has gained significant attention because not only exhibits good electrochemical performance (a high theoretical capacity of 170 mAh×g1 and a high discharge potential) but also it has other good features as: good cycle performance, low price, environmental benignity, high thermal and chemical stability [2]. However, low electronic conductivity and low Li+ diffusion rate limits the application of this material for high-power battery. To overcome these limitations it is necessary to synthesize nanosized LiFePO4 particles coated with carbon layer. A variety methods of preparation carbon coating were studied and existed because it is straightforward technology improving the conductivity of LiFePO4. It is still the challenge to prepare homogenous, highly conductive thin layer of carbon that does not block the lithium ion transfer between LiFePO4 and electrolyte [3].

The results of simple and environmental-friendly method of the carbon coatings on low-conductive cathode material powders have been developed, optimized and shown in this work. The carbon nanocoatings were prepared by wet impregnation process of precursor derived from hydrophilic polymer based on poly(N-vinylformamide) modified by pyromellitic acid [4] onto LiFePO4 particles.

The existence of nano-LiFePO4 was confirmed with X-ray powder diffraction (XRD). Transmission electron microscopy (TEM) was used to determine particle size and morphology of carbon nanocoated LFP material. The optimal calcination temperature of C/LFP composite precursors  were investigated from thermal gravimetry analyses (TGA/DTG/STDA). The properties of carbon nanocoatings were determined by Raman spectroscopy and electrical conductivity measurements. The process of formation C/LiFePO4 nanocomposite significantly enhances the electrical conductivity of the material and improves its capacity retention and electrochemical performance.

                                       

References

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

[2] Y.-D.Cho, G. Ting-Kuo Fey, H.-M. Kao, J. Power Sources 189 (2009) 256–262

[3] A. Örnekn, E. Bulut, M. Özacar, Ceramics International40(2014)15727–15736

[4] M. Molenda, R. Dziembaj, A. Kochanowski, E. Bortel, M. Drozdek, Z. Piwowarska, PAT.216549, Patent appl.: US 2011/015112
Preparation and Electrical Properties of Aluminum-Substituted Lithium Titanium Phosphates By a Novel Sol-Gel Method
Authors: Ma Qianli , Xu Qi , Tsai Chih Long , Tietz Frank , Guillon Olivier
Published: February 2020

The development of solid state electrolytes is regarded as the key point for the next generation of Li batteries. Among the candidates of possible lithium-ion-conductive solid electrolytes, Al-substituted LiTi2(PO4)3(LATP) were widely investigated as promising materials because of their relatively high ionic conductivity, chemical stability and mechanical strength. Preparation difficulties prevented practical applications of LATP and systematic studies on the processing of such materials are scarce. Moreover, published electrical properties showed a rather large scatter. In this study, LATP powders were easily prepared in kg-level and at low cost by a novel sol-gel method with high phase purity, densification activity and conductivity. So far, the highest ionic conductivity was obtained with Li1.5Al0.5Ti1.5(PO4)3. Electrical and microstructural properties of LATP samples with nonstoichiometry in Li and Ti position were also analyzed. Slight Li deficiency or Ti excess is beneficial for the conductivity of the samples. Moisture existing in ambient air is found to mislead the conductivity testing results. Reliable data should be tested in dry atmosphere. At 25 °C the conductivity of Li1.5Al0.5Ti1.5(PO4)3 is more than 1 × 10-3 and 5 × 10-4 S/cm in ambient atmosphere and dry argon, respectively.