bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications
Authors: Nielsen Jimmi , Persson Aasa Helen , Muhl Thuy Thanh , Brodersen Karen
Published: February 2020

Solid oxide fuel cell (SOFC) is attractive due to the excellent power generation efficiency and fuel flexibility. Conventional ceramic electrolyte and anode supported SOFC (AS-SOFC) is limited to stationary power generation applications as a result of the difficulty of quick startup and the high operating temperatures of 700 to 1000 °C. If quick startup of a SOFC is realized, mobile applications may be considered. To enable this, it is important to shorten the start-up time and reduce the heat cycle performance degradation and stack power density both in terms of weight and volume. As an approach to solving these problems, metal supported SOFC (MS-SOFC) has attracted attention. The development of this new generation of SOFC is currently in progress. DTU Energy’s MS-SOFC technology is based on co-sintering of laminated tape casted electrolyte, anode and support layers in a reducing atmosphere. This implies that the sintering shrinkage of the different layers should be matched sufficiently so that the mechanical stresses originating from any mismatch in sintering shrinkage of the individual layers during sintering can be absorbed by the cell structure. If the cell structure is unable to absorb the mechanical stresses, the cell will crack. Perfect matching of sintering shrinkage of the layers is practically very difficult as e.g. the electrolyte layer needs to be completely dense and thus gas tight, while the anode and support layers in contrast needs to be highly porous to allow sufficient gas transport. In the present study, we report on efforts of reducing the metal support thickness in DTU Energy´s MS-SOFC design. This is done to reduce the stack thermal mass during heat up and to increase the stack power density in terms of weight and volume. The results show an increased densification of the metal support layer as the support layer thickness is gradually reduce from 313 μm to 108 μm. This is due to sintering constraint. To counteract the metal support layer densification, the feasibility of creating gas channels within the support layer is explored. The gas channels are in this particular approach prepared by the creation of holes in the green tape casted support layer via puncturing. The study shows, that it is possible to lower the support thickness and thus the cell thickness. The study also shows that it is possible to counteract the increased support layer densification and resulting performance loss by the creation of gas channels in the support layer.
Effect of YSZ Volume on Polarization Resistance of Anode with Magnetically Aligned Ni
Authors: Nagato Keisuke , Shintani Kodai , Shikazono Naoki , Shimura Takaaki , Nakao Masayuki
Published: February 2020

In conventional solid oxide fuel cell (SOFC) anodes, yttria-stabilized zirconia (YSZ), Ni and pore phases are randomly distributed, where oxide ion, electron, H2 and H2O gases diffuse. These species electrochemically react at the triple phase boundaries (TPBs). From the viewpoint of tortuosity, aligned YSZ and Ni structure in the thickness direction is desirable, since it can reduce transport resistance. In our previous work [1], it was demonstrated that Ni particles can be aligned by applying the magnetic field during the drying process after screen-printing of Ni/YSZ paste. In this study, the Ni-YSZ volume ratio was varied to investigate the effect of the volume ratio on the polarization resistance of anodes fabricated with and without the magnetic field. In the conventional random structure, volume ratio of Ni and YSZ is generally kept at 50:50 to maintain active TPBs. Here, ionic conductivity of YSZ is much smaller than the electronic conductivity of Ni. Therefore, if Ni alignment can be improved by applying the magnetic field, YSZ volume fraction can possibly be increased, alternatively volume fraction of Ni can be reduced. The trade-off between the decrease in TPB length and the increase in ionic conductivity must be carefully investigated.

The volume ratio of Ni and YSZ was varied as 50:50, 33:67, and 20:80 in the present study. The Ni/YSZ paste was screen-printed on both sides of 200-mm-thick YSZ electrolyte substrate. During the drying process, magnetic field was applied along the thickness direction. After the anodes were sintered at 1400˚C in air, they were reduced in the furnace before the electrochemical measurement. The polarization resistance was measured by electrochemical impedance spectroscopy at 800˚C in 5%H2O, 95%H2 gas. Figure 1 shows the Nyquist plots of the symmetrical cells (a) without and (b) with the magnetic field. Without the magnetic field, the polarization resistance of the cell increased as the Ni volume fraction is reduced, which is reasonable from the percolation theory. On the other hand, with the magnetic field, the polarization resistances remained nearly unchanged. It is considered that the decrease in TPB length cancelled out the increase in ionic conductivity of the YSZ path. On the other hand, it is expected that the reduction of Ni volume fraction will lead to the improvement of durability of the cell, since strengthened YSZ skeleton may supress Ni agglomeration and the mismatch in thermal expansion between electrolyte and anode can be improved.

[1] K. Nagato, N. Shikazono, A. Weber, D. Klotz, M. Nakao, E. Ivers-Tiffée, ECS Trans. 57, 1307-1311 (2013).

Figure 1
Effect of Surfactants on the Physico-Chemical Characteristics of IrO/Ce0.8Sm0.2O2-δ Nanocomposite for SOFC Application
Authors: Njoku Chima Benjamin , Omondi B O , Ndungu Patrick
Published: February 2020

The sol-gel technique is a simple method that has been adapted to synthesize complex metal oxide formulations. The sol-gel technique takes advantage of the structural directing properties and templating characteristics of surfactant to produce porous Iridium oxide, with samarium doped ceria (SDC) nanoparticles. The nanoparticles were calcined at a temperature of 950 °C, and the nanostructural compositions were characterized by X-ray diffraction and high resolution transmission electron microscopy. The particle morphology and textural characteristics were respectively characterized by scanning electron microscopy and Nitrogen sorption at 77.5 K. The electrochemical properties were measured using a KITTEC SQUADRO muffle furnace and a SOFC testing equipment, with air and hydrogen as the gases used. The properties of the surfactant changed the particle morphology, pore diameter, pore size, crystallite size, surface area and electrochemical properties.
Review of Progress in Solid Oxide Fuel Cells at FuelCell Energy
Authors: Ghezel-Ayagh Hossein , Borglum Brian P
Published: February 2020

Significant progress has been made towards the development of Solid Oxide Fuel Cell (SOFC) at FuelCell Energy Inc. (FCE). The genesis of the advances in the technology is rooted in scale-up of the Company’s anode-support technology made by the TSC (Tape Casting-Screen Printing-Sintering) Process. The anode supported thin electrolyte planar cell platform was adopted for its higher power density at reduced operating temperature (600-800°C). Traditional materials, such as Ni/YSZ anodes, YSZ electrolytes and perovskite cathodes have been utilized in a basic cell structure. Research and development has been successful in developing better electrochemical functional areas at both cathode/electrolyte and anode/electrolyte interfaces. This was achieved through materials advancement, microstructure optimization, and manufacturing process integration. Cell materials development advancements have been made in performance, endurance, cell size (area) scale-up and cost reduction. These advancements led to an enhanced cell performance by reducing cell ASR (Area Specific Resistance) while reducing cell cost through cell design changes and materials reduction. Scaled-up cell size of up to 1000 cm2 have been made and tested with the current baseline cell size of 550 cm2 as the standard unit size for building SOFC stacks. The baseline stack design has been successfully scaled-up from 120-cell 550 cm2 cell area (16 kW nominal) stack. Using standardized manifolds and gas-electrical interconnects, these stacks have been successfully integrated into stack towers and arrays.

FCE recently designed, built, and tested a 50 kW fully automated SOFC system under a Co-operative Agreement with Department of Energy. In a follow-on DOE supported project, currently, FCE is engaged in design and construction of larger 200kW units that utilize baseline factory-built stack blocks representative of the future MW-scale power plants.
Design and Optimization of Chromium Getter for SOFC Systems through Computational Modeling
Authors: Uddin Md Aman , Banas Charles Joseph , Liang Chiying , Pasaogullari Ugur , Recknagle Kurt P , Koeppel Brian J , Stevenson Jeffry W , Singh Prabhakar
Published: February 2020

Chromium poisoning is one of the major causes of cathode degradation in high temperature electrochemical systems such as solid oxide fuel cells, electrolyzers and oxygen transport membranes. Chromium species, evaporating from the chromia forming metallic balance of plant and cell interconnect components, deposit at the exposed electrode surface and triple phase boundaries resulting in irrecoverable performance degradation. Chromium capture approach comprising of the use of non-noble and non- strategic getter materials and conventional ceramic support, currently being developed and tested in our laboratory, will be presented and discussed. Simulation of the chromium getter under nominal SOFC system operating conditions include a single channel with porous region at the wall to simulate the getter coating on cordierite honeycomb support (400 cells per square inch) with a coating thickness of 10µm and 50% porosity. The model is validated against experimental data and utilized to study the effects of the key parameters such as chromium partial pressure, air flow rate, geometric surface area, porosity, and thickness of coating materials.
Development Progress on the Ceres Power Steel Cell Technology Platform: Further Progress Towards Commercialization
Authors: Leah Robert Timothy , Bone Adam , Hammer Eva , Selcuk Ahmet , Rahman Mahfujur , Clare Andrew , Mukerjee Subhasish , Selby Mark
Published: February 2020

Ceres Power is continuing to make excellent progress in the development of its low-temperature metal supported SOFC design (the ‘Steel Cell’) based predominantly around the use of ceria. This unique design architecture allows for a robust, low cost, subsidy free fuel cell product, whilst retaining the advantages of fuel flexibility, high efficiency and low degradation.

Over the last year, several significant technological and commercial developments have taken place. The latest generation of SteelCell technology (v4.0) has completed validation and verification testing, and is now the standard version of the technology offered to customers. The v4.0 cell/stack technology has a significantly simplified and lower-cost manufacturing process relative to earlier technology generations, whilst offering improved performance and comparable degradation. v4.0 stacks have been incorporated into natural-gas fuelled Ceres Power SteelGen 700We micro-CHP demonstrators, which have been deployed in several locations in the UK as part of a field trial in association with British Gas funded by the European Ene.field program. In addition to this Ceres is also working with Nissan to evaluate the application of SteelCell technology to an electric vehicle range extender application, taking advantage of the thermal cycle and mechanical robustness of the technology, which is at least an order of magnitude better than published data from any other SOFC stack developer.

In addition to an ongoing joint development agreement with Honda, Ceres has also been granted a US DoE grant working with Cummins on a 5kWe-class stationary power generator for use in data centers. Ceres has also announced a joint development and licensing agreement with another large global OEM to develop a multi-kWe-scale micro CHP system.

A major focus of ongoing technology development is to further improve stack power density, durability and efficiency in line with the technology roadmap for next generation products. Significant progress has been demonstrated at the R&D level on all of these requirements, and the design improvements to achieve them will be incorporated into the next generation of SteelCell technology.
Effect of Infiltrated Transition Metals in Ni/Sm-Doped CeO2 Cermets Anode in Direct NH3-Fueled SOFCs
Authors: Zhang Mengjia , Hashinokuchi Michihiro , Yokochi Ryuji , Doi Takayuki , Inaba Minoru
Published: February 2020

Ammonia (NH3) has attracted much attention as a fuel for SOFCs. In the case of well-established Ni-based cermets anode, however, the cell performance is poor due to the low catalytic activity for NH3 reforming. In this respect, it is necessary to develop the highly active anode for realizing direct NH3-fueld SOFCs.

Previously, we prepared Ni-M (M : Mo, Ta, W and Nb)/ Sm-doped CeO2(SDC) anodes by infiltration of metal solutions into pre-sintered Ni/SDC cermets and revealed the activity of them as an anode for direct NH3-fueled SOFCs at temperature of 700 to 900 °C [1-2]. From these studies, we have proposed that the synergetic effect of Ni and added metals, which weakly and strongly bind to N atom, enhances the activity of the anodes for NH3 oxidation(NH3 reforming, followed by hydrogen oxidation). In addition, it was found that the enhancement of the activity for NH3 oxidation strongly depended on the added metal. Among them, Mo was the most effective element as an additive. On the other hand, the obvious enhancement of the activity for NH3 oxidation was not observed when Nb, Ta and W were added, which have the larger metal-nitrogen (M-N) binding energy than Mo. The activity of the Ni-M binary anode seemed to be determined by the interaction potential between catalytic surface and N atom, produced by Ni and added metals. Here, we focus chromium(Cr) and vanadium(V) as an additive, because Cr and V have the moderate M-N binding energy (ranked in the order of Mo < Cr < V < W < Nb < Ta) among the metals used in our previous studies.

The addition of Cr and V into the Ni/SDC cermets enhanced the activity of the anode for NH3 oxidation at temperature of 700 to 900 °C. The formation of Ni metal and nitrides (CrN and VN) was confirmed in each anode at 700 °C. This suggests that the synergetic effect of Ni and Cr(V), which has weekly and strongly bind to N atom enhances the activity of the anode for NH3 oxidation. Cr was more effective than Mo as an additive, but V was not. The relationship between the activity of the anode and the M-N binding energy of the added metal are discussed.

Acknowledge

This work was supported by “Kyoto Environmental Nanotechnology Cluster” and “Kyoto Regional Scientific Innovation Hub” from MEXT in Japan.

 

Reference

[1] M. Hashinokuchi et al., Solid State Ionics, 285, (2016) 222

[2] R. Yokochi et al., ECS Trans. 68(2015) 2745.
Designing the Composite SrVO3-SrTiO3 Anodes for Hydrocarbon-Fueled Solid Oxide Fuel Cells
Authors: Yaremchenko Aleksey , Macias Javier , Frade Jorge
Published: February 2020

Perovskite-type SrVO3- and SrTiO3-based phases exhibit good resistivity to sulfur poisoning and do not catalyze carbon deposition, and are considered therefore as possible alternative anode materials for hydrocarbon-fueled solid oxide fuel cells. SrVO3 exhibit high electronic conductivity but also a narrow phase stability domain restricted to reducing conditions. On the other hand, SrTiO3 demonstrates remarkable phase and dimensional stability in a wide range of T-p(O2) conditions but rather insufficient electrical conductivity. The present work aimed at the development of SrVO3-SrTiO3 composite anode materials with emphasis on a compromise between dimensional/microstructural stability and electrical properties.

Initial assessment demonstrated that SrVO3 and SrTiO3 form an entire range of solid solutions under reducing conditions. In all cases, exposure to air above 600-700°C resulted in either collapse of perovskite structure (V-rich compositions) or separation of vanadium-containing secondary phases (Ti-rich composition). These phase transformations were accompanied by dimensional changes and were not reversible at temperatures below 1000°C (probably, due to kinetic reasons).

Instability in oxidizing atmospheres complicates the fabrication of anodes in realistic conditions. Therefore, the second approach was to start from oxidized phases and to proceed via in-situ reduction employed for Ni-YSZ cermet anodes. V5+ substituted in titanium sublattice of SrTiO3 acts as donor-type dopant and was found to has a limited solid solubility under reducing conditions (~30-35 at.%). In-situ reduction of oxidized SrTi1-y
V
y
O±δ at 900°C is accompanied however by the reduction of vanadium cations, and the resultant conductivity remains too low (< 0.2 S/cm) being comparable to other acceptor-doped strontium titanates.

The next approach was preparation of composite SrVO3-SrTiO3 anode materials starting from oxidized phases. The precursors with nominal composition SrTi1-y
V
y
O±δ (y = 0.1-0.4) were thermally treated in air at temperatures not exceeding 1100°C to yield equilibrated phase mixtures comprising SrTiO3-based perovskite as a main phase and strontium orthovanadate Sr3(VO4)2 as a second major phase. Transformation of strontium orthovanadate on reduction at 900°C into highly-conductive perovskite-type SrVO3 phase finely distributed in the stable SrTiO3-based matrix resulted in substantial nearly instant increase of electrical conductivity by orders of magnitude reaching 10-30 S/cm for y = 0.3-0.4. Electrochemical activity of composite anodes applied onto yttria-stabilized zirconia solid electrolyte and infiltrated with a fraction of Ce0.9Gd0.1O2-δ electrolyte component was evaluated by electrochemical impedance spectroscopy using symmetrical cell configuration.
Analysis of Gas Leakage and Current Loss of Solid Oxide Fuel Cells by Screen Printing
Authors: Jia Chuan , Han Minfang , Chen Ming
Published: February 2020

One of the biggest advantages of SOFC (solid oxide fuel cell) is the probable use of methane as fuel. However, when the actual SOFC stack is operating with CH4 as fuel, due to the catalytic action of metal nickel, carbon will deposit on SOFC anode and nickel foam, which directly shorten the SOFC operating life and lead to performance degradation. The planar anode-supported Ni-YSZ|YSZ|LSCF SOFC was chosen as the research object, with the cell size of 12cm×12cm and the effective area of 100cm2, and the holder is made of 99% purity of Al2O3 ceramic material, in order to eliminate the influence of Cr in stainless steel. The one-cell stack operated at 750℃, and the maximum power density was 0.35W/cm2 when the fuel is 0.5slm/min pure hydrogen. The stability experiment was conducted first under pure H2 for 100h, then fuel was switched into pure methane, and another 100h of voltage stability was tested. In this work, the temperature distribution of the stack was monitored, whose relationship with the weight gain and the micro-structure of the nickel foam was established, and a possible explanation of the carbon deposition distribution and process on the nickel foam was put forward.
Integration of a Solid Oxide Fuel Cell with an Absorption Chiller for Dynamic Generation of Combined Cooling and Power for a Residential Application
Authors: Asghari Maryam , McVay Derek , Brouwer Jack
Published: February 2020

Our novel idea is a highly efficient, zero emission solid oxide fuel cell (SOFC) system that can be dynamically dispatched to produce electricity, hydrogen fuel, and cooling in various amounts to meet energy and power demands of a single residence. Although SOFC systems exhibit high electrical efficiency, in practical applications almost half of the fuel energy is converted to heat. The SOFC high temperature (high quality) heat can be used as the primary thermal energy source to supply cooling or heating or to produce extra electricity through a bottoming cycle. In this study the waste heat from the fuel cell is captured and processed through an absorption chiller (AC) to provide cooling for meeting the cooling demand of a single residence. High purity hydrogen gas can also be produced by the SOFC system as an energy co-product using the tri-generation concept of lower fuel utilization followed by hydrogen separation from the anode off-gas. Hydrogen as an energy carrier can be stored for later use, as fuel for transportation use in a fuel cell electric vehicle. The integration of an absorption chiller and hydrogen separation unit with an SOFC could create a highly dispatchable system that can meet the dynamics of measured residential power and cooling while producing hydrogen fuel for fuel cell electric vehicle demand. Dynamic dispatch and control strategies are needed to safely operate such an SOFC system, keep it within the required operating envelope, and avoid premature degradation.

A spatially resolved dynamic model was developed in Matlab/Simulink to simulate the dynamic operating characteristics of an SOFC system. A commercially available 1.5 kW SOFC system was selected and acquired for model verification and performance evaluation. Preliminary results from the dynamic model of the SOFC show that the SOFC exhaust retains sufficient quality heat for use in an absorption chiller. A dynamic absorption chiller model is developed to study the dynamic characteristics and the performance of the combined co-generation system. Actual dynamic data from a single residential house located in Irvine California is used as an input to evaluate the dynamic operation of the SOFC-AC model. The integrated Tri-generation system was then evaluated in terms of efficiency, capacity, dynamic operation and control to meet the measured power, cooling, and fuel demands of the residence. The proposed system may offer a high efficiency and low emissions conversion solution that meets the dynamic demands for residential power, cooling, and transportation end-uses.
Highly Thermal-Integrated Flame Fuel Cell Module with High Temperature Heatpipe
Authors: Zeng Hongyu , Wang Yuqing , Shi Yixiang , Cai Ningsheng , Ye Xiaofeng , Wang Shaorong
Published: February 2020

Flame fuel cell(FFC) is a novel kind of fuel cell coupling rich-flame and solid oxide fuel cell(SOFC) together. With rich-flame as both heater and reformer, FFC takes advantages of quick start-up, no sealing and low cost. However, for the temperature distribution is determined by flame, temperature nonuniformity is a significant problem, especially along the axis direction of the tubular SOFC or within SOFC stacks. Due to great temperature gradient and insufficient thermal shock resistance, micro cracks occur inside the cell, resulting in a low open circuit voltage and failure of FFC. Relatively low temperature in partial regions of SOFC also leads to a low power density. In this paper, a high temperature heatpipe was introduced to a flame fuel cell module to lower the temperature gradient and improve the performance of the whole SOFC. A highly thermal-integrated FFC module with a two-layer porous media burner, micro-tubular SOFCs and an annular high temperature heatpipe was designed and tested. The temperature difference along the axial of the tubular SOFC decreased from 34°C/10 mm to 12°C/10 mm due to the high heat conductivity of the heatpipe. By integrating with a heatpipe, the power output for a single fuel cell increased from 0.88 W to 1.54 W at 0.7 V with a methane-rich flame at an equivalence ratio of 1.6. The FFC module with four cells showed considerable performance and had the potential for fabrication of FFC stacks.
Structure-Electrochemical Property Relationships of Lipons Thin-Films Electrolytes for All Solid-State Microbatteries
Authors: Morin Pierrick , Le Van-Jodin Lucie , Benayad Anass , Bouchet Renaud
Published: February 2020

All-solid-state microbatteries have interested many researchers and companies for the last decade, in order to supply in electrical energy small sensors and connected object. In these systems, Lithium Phosphorus Oxy-Nitride (LiPON) is generally used as solid-state electrolyte since its discovery in the early 1990s by Bates et al. [1]. However, LiPON presents a quite low ionic conductivity around 10-6 S/cm at room temperature. To increase this value, Sulfur can be added to the LiPON structure [2,3]. The present work focuses on the deposition of LiPONS thin-film electrolytes, and their chemical, structural, and electrochemical properties.

LiPONS glassy films were deposited by reactive radio-frequency magnetron sputtering from a pure Li3PO4 target at room temperature in a mixed N2:H2S plasma, with H2S gas flow varying from 0 to 5% to fine tune the S concentration in the LiPONS thin films. LiPOS materials were also obtained by sputtering the same target under a Ar:H2S plasma. Constant power, pressure and deposition time were used. Potentiostatic Electrochemical Impedance Spectroscopy (PEIS), Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS) measurements were performed to probe the changes in morphology and composition, and understand the structure-electrochemical property relationships.

Whereas an improvement of the electrochemical properties of LiPON with the addition of Sulfur was expected, the opposite occurred (Fig. 1). In order to correlate the chemical structure to the ionic conductivity and identify the causes for the performance degradation, the electronic structure of LiPONS and LiPOS materials will be discussed based on XPS core level and valence band structure analyses, and compared with the classical LiPON electronic structure.

The observed decrease in ionic conductivity when the S content in the LiPONS thin-films increases from 0 to 15 at% (Fig. 1) can be related with the appearance of two groups of species in the High-resolution S2p XPS spectra (Fig 2). For low S concentrations, doublets from 160 to 164 eV assigned to S-P structures are dominant whereas signals from 165 to 168 eV, corresponding to more oxidized S species that can originate from reactions between Sulfur and Nitrogen, become non-negligible at higher S-contents and may be the cause of the electrochemical properties degradation.

[1] J. B. Bates, N. J. Dudney, G. R. Gruzalski et al, Solid State Ionics, vol. 53–56, pp. 647–654, 1992.

[2] J. B. Bates, “Thin film battery and electrolyte therefor,” US 6,818,356 B1, 2004.

[3] N. Mascaraque, H. Takebe, G. Tricot et al, J. Non.
Cryst. Solids, vol. 405, pp. 159–162, Dec. 2014.

Figure 1
Development of Electrolyte for Negative-Limited LiNi0.5Mn1.5O4 / Li4Ti5O12 Li Ion Cells
Authors: Gogyo Yuma , Fukuta Ryuichiro , Onuma Takamitsu , Nishimura Takuya , Kojima Katsunori
Published: February 2020

Spinel Li4Ti5O12 (LTO) is an attractive candidate for negative electrode materials of lithium ion battery because the LTO anode shows the high rate capability, long cycle life, outstanding safety characteristics, and a flat insertion/extraction potential of at 1.5 V vs. Li+/Li. The 4V-class cathode (such as LiCoO2, LiNi1/3Mn1/3Co1/3O2, and LiMn2O4) / LTO battery has a low working voltage of about 2.5 V, leading to its low energy density. Some researchers have studied the LiNi0.5Mn1.5O4 (LNMO) / LTO battery system, because LNMO cathode offers a high operating potential at 4.7 V, which increases the working voltage of the battery using the LTO anode to 3.1 V [1] [2] [3]. Amine et al. reported that the negative limited LNMO / LTO cell showed a high rate capability and long cycle life at room temperature [1].

However, we found that the negative-limited LNMO /LTO battery showed a poor cycle characteristic at 50 ℃ (figure1-a). In this presentation, we aim to clarify the degradation mechanism of the negative-limited LNMO / LTO battery in order to improve the cycle life at a high temperature.

For this purpose, we disassembled the LNMO / LTO cells after the cycle test at 50 ℃ and extracted the electrodes and electrolyte. The extracted LNMO / Li-metal half-cell and the extracted LTO / Li-metal half-cell were assembled and tested. It was found that the capacity of the LNMO electrode did not decrease. On the other hand, the capacity of the LTO electrode decreased. It is revealed that the degradation of the negative-limited LNMO/LTO battery was caused by the decline of the LTO anode capacity. The XPS spectra of the LTO electrode indicated that LiF covered around the LTO materials and caused its capacity degradation.

To reveal the generation pathway of LiF, the extracted electrolyte was analyzed by GC-MS, LC-MS/MS and 19F-NMR. The results revealed that the reduction reaction of the chain-like carbonate such as dimethyl carbonate and the ring-opening reaction of the cyclic carbonate such as ethylene carbonate caused the LiF generation. Especially, the lithium alkoxide generated by the ring-opening reaction of the cyclic carbonate accelerated the LiF generation reaction.

The use of the electrolyte containing only chain-like carbonate as a solvent significantly improved the cycle characteristics at 50 ℃ (figure1-b).

References

[1] H. M. Wu, I. Belharouak, H. Deng, A. Abouimrane, Y.-K. Sun, and K. Amine, J. Electrochem. Soc., 156(12)　A1047 (2009)

[2] S. R. Li, C. H. Chen, X. Xia and J. R. Dahn J. Electrochem. Soc., 160(9)　A1524 (2013)

[3] Burak Aktekin, Reza Younesi, Wolfgang Zipprich, Carl Tengstedt, Daniel Brandell,

and Kristina Edstr¨om J. Electrochem. Soc., 164(4) A942 (2017)

Figure 1
Li-Ion Battery Applications of Nanocellulose Based High Aspect Ratio Nanostructures
Authors: Youn Chulmin , Kim Hyunwoo , Kim Youngsik , Choi Taekjib
Published: February 2020

Nanocellulose is considered as the sustainable materials due to renewability, affordability and non-toxicity in nature. As a chemical raw material, nanocellulose can form flexible or strong networks that are suitable templates for artificial nanostructure with enhanced electrochemical performances. Here, we prepared nanocellulose-metal oxide hybrid nanostructure from cellulose nanofibrils and oxide nano belt via hydrothermal method using transition metal oxide precursor and TEMPO oxidized cellulose nanofibers. Oxide nanobelts with high aspect ratio are structurally uniform and single crystalline. The as-prepared and carbonized oxide nanobelts are compared regarding electrochemical performance for Li-ion batteries. Carbonized nanocellulose-metal oxide hybrid nanostructure prepared fast charging and discharging capability with high capacity and long cycle performances. Our hybrid nanostructure can provide a new route into the development of high capacity, unique architecture, and suitable electrode potential for promising electrode materials.
Electrochemical Plating/Stripping Behavior of Metallic Zn on Carbon Film Current Collector
Authors: Li Wei , Wang Kangli , Cheng Shijie , Jiang Kai
Published: February 2020

Aqueous batteries are promising as cheap, safe and green energy storage technologies. In the family of aqueous batteries, Zinc-based alkaline batteries are attractive candidates due to their low cost and high capacity compared with lead-acid and nickel-metal hydride batteries.1-3 However, the long-term durability of Zinc-based alkaline batteries is hampered by the Zn dendrite formation, which easily causes the internal short of batteries. In order to address this obstacle, a carbon film is developed to serve as flexible current collector for the plating/stripping of Zn. By virtue of this carbon film current collector, Zn can be reversibly plated/stripped at 1 mA cm-2 at 1 mAh cm-2 for 100 cycles with the coulombic efficiency over 97% without the formation of Zn dendrite.

Figure1a shows the cycling performance and coulombic efficiency of Zn plating and stripping on carbon film at a current density of 1mA cm-2 with an areal capacity of 1mAh cm-2. During each cycle, Zn is deposited on the carbon film at 1 mA cm-2 for 1 h and then stripped at 1 mA cm-2 until the potential reaching 0.5 V (vs. Zn2+/Zn). The coulombic efficiency is defined as the ratio of Zn removed from carbon film to that deposited during the same cycle. As can be seen, Zn can be stable deposited on and stripped from the carbon film within 100 cycles without short circuit. The initial coulombic efficiency of is 92.6% but it quickly roses up to 97.3% in the 3rd cycle and is stabled over 97% within 100 cycles. Moreover, from the plating and stripping profiles of Zn in Figure 1b, the potential hysteresis (defined as the difference of stripping/plating average potential in the same cycle) between the plating and stripping is less than 200 mV, indicating a fast electrochemical reaction kinetics. This result demonstrates that this low cost, fast kinetics and high efficiency carbon film shows potential as current collector for aqueous zinc-based batteries.

Acknowledges: The authors greatly acknowledge the financial support from National Natural Science Foundation of China (No. 51622703), and the National Thousand Talents Program of China.

References

F. Parker, C. N. Chervin, I. R. Pala, et al., Science, 2017, 356, 415.

Pan, Y. Shao, P. Yan, et al., Nature Energy, 2016, 1, 16039.

Kundu, B. D. Adams, V. Duffort, et al., Nature Energy, 2016, 1, 16119.

Figure 1
Investigations of the Structural and Electrochemical Properties of Overcharged Li-Ion Batteries
Authors: Torres-Castro Loraine , Lamb Joshua , Steele Leigh Anna M , Quintana Genaro
Published: February 2020

Traditional monitoring of electrochemical cells and batteries has been limited to observation of voltage and temperature of the cell or cells. While this monitoring can be very robust, there are limits to how predictive voltage and temperature behavior can be prior to a thermal runaway event. Ultimately, voltage and temperature changes are often lagging symptoms of battery failure, and by the time a noticeable change is detected it is too late to arrest cell failure with intervention or maintenance. Further, instantaneous voltage and temperature monitoring are often inadequate to determine the state of a battery at rest, particularly if the battery has been previously subjected to an abusive condition. Knowledge of the level of stability of a damaged battery would allow for both safer and more efficient handling of the abused battery.

This work examines the application of Electrochemical Impedance Spectroscopy (EIS) and Differential Capacity calculations (dQ/dV) as tools for determining the state of stability (SOS) of an electrochemical cell or battery. The cells used for this study were commercial 10 Ah NMC cells and 10Ah LFP cells subjected to electrical abuse coupled with EIS monitoring. This aims to not only provide a deeper understanding of how abused cells and batteries fail, but also form the technical basis of a tool that could ultimately be used to interrogate cells of an unknown stability and even monitor active cells for early signs of damage or failure. Fast impedance monitoring hardware previously developed at Idaho National Laboratory is used to provide not only monitoring after an abusive battery test but also look for changes in the cell while abusive conditions are applied. Differential capacity calculations are explored both before tests and after moderate levels of overcharge to explore any observable changes that may be monitored during charge and discharge operations. Lastly, X-ray diffraction measurements were performed on the cathode/anode before and after the abuse test to understand the effect of overcharge in the structural changes. Figure 1 presents the measurements for the NMC cells that were partially abused from 20-60% OC. These three markers could then be potentially applied to cross-examine batteries of an unknown stability as well as provide the basis for an active diagnostic method as part of a battery management system.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

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Widened Voltage Window for Aqueous Li-Ion Batteries with Low Electrolyte Concentrations
Authors: Lin Yu-Hsiang , Luo Jing , Wu Nae-Lih
Published: February 2020

Nowadays, most of commercial Li-ion batteries use organic-based electrolytes, but the organic components are encountering several safety and environmental concerns. For example, ester based solvents are highly flammable and reactive with electrodes. These safety concerns are hindering the development of energy storage devices for high energy applications, such as electric vehicles and grid storage. Aqueous-based electrolytes may alleviate these safety concerns with several additional potential advantages, such as high conductivity and low cost. Nevertheless, aqueous-based electrolyte systems suffer from narrow operation voltage window (1.23 V), as aqueous-based electrolytes due to water-splitting reaction at both the high potential (3.7 V versus Li/Li+, oxygen evolution reaction) and low potential (2.5 V versus Li/Li+, hydrogen evolution reaction). New approaches based on water-in-salt concept, which involves very high slat concentrations (e.g., 21m LiTFSI(aq)) to reduce water decomposition reactions, have recently been proposed for widening the voltage window. The extremely high salt concentrations used in these new approaches impose serious cost and new safety concerns. In this work, a new method using electrode surface modification to reduce the salt concentrations needed for widened voltage windows is explored. The surface modification is shown to be effective in reducing water reduction toward the lower end of the voltage window. As a result, a significantly widened operation voltage window can be achieved with salt concentrations that are substantially lower than those typically reported in the water-in-salt methods.

Figure 1: Cyclic voltammetry test of Ti current collectors with or without surface modification in 1m LiTFSI(aq).

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NMR Characterization of the Na+ Ion Transport in Mixed Ionic Liquids Electrolytes
Authors: Suarez Sophia , Gomes Chagas Luciana , Passerini Stefano
Published: February 2020

In the market of medium- and large- scale energy supplies, sodium (Na+) ion batteries are considered a possible alternative to current technologies. This is because sodium is naturally more abundant and cheaper than the ubiquitous lithium. Room temperature Na+ batteries typically employ organic solvents such as propylene carbonate. However, room temperature ionic liquids – while more viscous – are safer, and because of this attention is being paid towards their partial or complete replacement of organic solvents. Towards this endeavor, we investigated ions dynamics in mixtures of varying concentrations of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) or sodium bis(fluorosulfonyl)imide (NaFSI) salts, combined with the 1-butyl-1-methylpyrrolidinium (PYR1,4) FSI and PYR1,4 TFSI ionic liquids. We used variable-temperature 1H and 23Na Nuclear Magnetic Resonance (NMR) spin-lattice relaxation times (T1) and self-diffusion coefficients (D) measurements to investigate the short- and long- range ions dynamics and a preview of or results are shown in Figure 1. Both T1 (1H and 23Na) and 1H D data show greater short- and long- range dynamics for mixtures containing the FSI salt or ionic liquid. A more comprehensive discussion will be presented.

Figure 1. Variable-temperature Na+ spin-lattice relaxation times (left) and 1H self-diffusion coefficients (right) for mixtures of various mol% of NaFSI or NaTFSI salt with PYR1,4 based ILs.

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Studying Break-in Phenomena in Lithium-Ion Batteries through Acoustic and Impedance Measurements
Authors: Hodson Thomas , Knehr Kevin William , Steingart Daniel A
Published: February 2020

Lithium-Ion Batteries (LiBs) have become ubiquitous in modern technologies, such as in the burgeoning electric vehicle and consumer electronics markets. After manufacturing the LiB, a period of “break-in” occurs wherein the battery experiences rapid changes in properties, such as capacity [1] and stress [2], before leveling off to a stable value. Most research in LiBs analyze the full cycle life of the battery and have little regard for the initial break-in period. However, understanding and controlling break-in conditions could determine future performance of the cell. In this study, we use electrochemical acoustic and impedance spectroscopy measurements to analyze break-in of LiBs. We further analyze how break-in conditions, such as varying the rate of current, affect the overall performance of the battery.

[1] Hong, Jong‐Sung, et al. "Electrochemical‐calorimetric studies of lithium‐ion cells." Journal of the Electrochemical Society 145.5 (1998): 1492

[2] Liu, Xinyi M., and Craig B. Arnold. "Effects of Cycling Ranges on Stress and Capacity Fade in Lithium-Ion Pouch Cells." Journal of The Electrochemical Society 163.13 (2016): A2501-A2507.
In-Operando Surface Chemistry of Nickel and Copper Current Collectors During Zinc Electro-Deposition and Dissolution
Authors: Turney Damon , Gallaway Joshua W , Yadav Gautam Ganapati , D'Ambrose Michael , Banerjee Sanjoy , Huang Jinchao , Kolhekar Snehal
Published: February 2020

Zinc electrodeposition from alkaline solutions is of renewed interest due to MnO2-Zn and Ni-Zn grid-scale energy storage devices. Control and understanding of the rechargeable zinc electrode remains difficult, and several Zn battery technologies suffer from a failure to deposit zinc after many cycles. The predominant substrates for zinc energy storage in zinc electrodes are copper and nickel. Here we study the performance of zinc electrodeposition onto nickel and copper substrates in an alkaline battery device, with the aim to identify the nanoscale surface chemistry that mediates the decreased electrodeposition performance. We find the coulombic-efficiency of the zinc cycling process to drop from 99% to ~50% under various operating conditions for electrodeposition, for both zinc and copper substrates. We present grazing-incidence x-ray diffraction measurements in-operando on the nickel surface, to identify the crystallography of nanoscale surface layers that form during cycling of the battery. Our results suggest the presence of zinc oxide and zinc peroxide layers on the nickel surface affects the coulombic efficiency of zinc cycling. We find that nanoscale layers of zinc oxide aids the zinc electrodeposition and allows charge-efficiency to be high. If the nickel anode surface is exposed to voltages ~0.5 V above zinc’s rest voltage this zinc oxide layer disappears, leaving behind a relatively bare nickel surface that has very poor zinc electrodeposition charge-efficiency due to nickel’s catalytic generation of hydrogen gas. The beneficial zinc oxide layer is seen to grow thicker during normal cycling and during open circuit rest over many hours. Similar performance problems are shown for copper current collectors. X-ray photoelectron spectroscopy and electron microscopy is performed on the copper current collectors, which uncovers the formation of a composite zinc-copper nanoscale layer that impedes zinc electrodeposition during battery charging. Electrochemical growth and dissolution of this zinc-copper layer is hypothesized to interact with shape change of the zinc electrode. In the case of both copper and nickel the formation of these layers is caused by undesired oxidation that arises due to microscopic variations in OH- and H2O concentration. Possible strategies for improving the long-cycle performance of zinc electrochemical energy storage are given.
Ultrahigh Volumetric Pseudocapacitance of Conducting Polymer Networks
Authors: Park Ho Seok
Published: February 2020

High volumetric energy density is demanding for space-limited applications such as electric vehicles (EVs) and portable mobiles. Supercapacitors have better cyclic and power capabilities compared to batteries; they are still restricted by low volumetric capacity due to low density of active materials (< 0.75 g/cc of AC) and intrinsic non-Faradaic charge storage process. To resolve these challenges, we demonstrate ultrahigh volumetric capacitance of conducting polymer networks through the pseudocapacitance with significant durability. The charge storage mechanism of the as-designed conducting polymer hybrid networks for the exceptional volumetric pseudocapacitance was deeply investigated by in-situ ATR-FTIR spectroscopic and ex-situ XPS analyses. The results will inspire to architecture other organic hybrid networks in an analoguous manner for new energy storage materials and put forth new avenue for the design of high volumetric energy storage materials through the redox charge transfer.
Mechanical and Electrochemical Properties of a Composite Structural Supercapacitor
Authors: Wang Yuchen , Qiao Xiaoyao , Zhang Chen , Zhou Xiangyang
Published: February 2020

Composite structural supercapacitors were fabricated using an adhesive polymer electrolyte, mixture of epoxy, PVDF, and lithium trifluoromethanesulfonate (LiTFS). Multi-cell supercapacitors were made into composite panels. Each cell has a planar configuration with metal foils and carbon fiber as mechanical reinforcements/currrent collectors, carbon powder/carbon naotubes as active materials, and the adhesive polymer electrolyte as the matrix. A systematic study on the adhesion, in-plane tensile strength, and conductivity versus composition of the adhesive polymer electrolyte was conducted. The conductivity of the epoxy based adhesive polymer electrolyte is in the magnitude of 10-2 S cm-1 when the concentration of epoxy resin is less than 30%. Structural SCs were fabricated using a vacuum bagging method. The maximum specific energy is achieved as 2.64 Wh kg-1. The mechanical property of the structural SCs in this work is acceptable. The greatest ultimate tensile strength (UTS) of the structural SC can reach 80 MPa while the UTS of the baseline structural SC is 112 MPa. The strength of the structural SCs can be improved significantly using a stronger epoxy. The response of electrochemical performance of the structural SCs to in-plane tensile stress was studied. Before fracture, the specific power and the specific energy increases slightly or remains the same.

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Hybrid Supercapacitor-Rechargeable Battery Based on RbAg4I5 Ceramic Electrolyte
Authors: Wang Yuchen , Qiao Xiaoyao , Zhang Chen , Zhou Xiangyang
Published: February 2020

An all-solid-state hybrid supercapacitor/rechargeable battery with RbAg4I5 superionic ceramic electrolyte was fabricated without air-proof sealing. The ionic conductivity of RbAg4I5 powders was 0.21 S cm-1. The all-solid-state SC/battery can work in oxygen and moisture environment at room temperature. The all-solid-state energy storage device shows both SC-like and battery-like behaviors. The maximum specific energy of the all-solid-state SC was more than 60 Wh kg-1. The ESR of the all-solid-state SC increases with charge/discharge cycles. The charge capacity first increases and then decreases with charge/discharge cycles. However, the charge capacity can be recovered by conducting an annealing process at 150°C for 12 hours. The possible reason is that Rb2AgI3 and AgI produced in charge/discharge cycles are converted back to RbAg4I5 in the annealing process. X-ray diffraction analyses were conducted before and after a number of charge/discharge cycles and before and after the annealing process. It was also found that air and or moisture were necessary for the electrochemical charge/discharge processes. Systematic heat treatments and electrochemical measurements were conducted to specify the optimal operational parameters and for elucidating the charge/discharge mechanisms of the hybrid supercapacitor/battery. The experimental results indicate that the main charge/discharge mechanism is redox reactions of the electrolyte and little electrode material is consumed. Thus, the electrodes can be made very thin to reduce the total mass and increase the specific energy and power.

Figure 1