bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Battery Design Principles for Highly Safe, High Energy Density Lithium Ion Battery Using Less Volatile Electrolyte
Authors: Unemoto Atsushi , Seki Eiji , Konishi Hiroaki , Nishimura Katsunori , Kawaji Jun , Okumura Takefumi 
Published: February 2020

Enhancing battery energy density is of particular importance for distributing electric vehicles and stationary uses. For EV uses, high energy density battery allows for longer driving distance per a charge, and cycle life, while it leads to an enlarged risk on safety. Hence, it exists a trade-off relationship between energy density and safety for battery packs developed for EVs.
Safety failure in the current lithium ion battery is often related to an explosion of a volatile and flammable electrolyte liquid. Once internal short takes place irregularly, joule heat generation takes place and thereby it leads to the explosion of volatile and flammable electrolyte as this called thermal runaway. In addition, fields of the battery used is limited, namely, the battery use in the enclosed space is likely to be prohibited to prevent the leakage of toxic and volatile electrolyte liquid into the space.
To overcome the issues related to the battery safety, we recently developed a novel electrolyte having a lower vapor pressure electrolyte than the conventional organic liquid electrolyte, and applied the electrolyte to lithium ion battery with a high energy density. A repeated operation of the battery was successfully demonstrated.
In this presentation, the concept our electrolyte, and evaluated results on electrolyte volatility and charge-discharge property of the battery will be reported.
Effect of LiNO3 Electrolyte Additives for Improved the Rate Capability of Micro-Patterened Lithium Metal Anode
Authors: Jin Dahee , Oh Jeonghun , Yoon Byeolhee , Park Jinkyu , Lee Yong Min , Ryou Myung-Hyun 
Published: February 2020

The commercialization of Li metal electrodes is a long-standing objective in the battery community for electric vehicles (EVs) and energy storage systems (ESSs) due to its high theoretical specific capacity of 3,860 mAh g-1 and lowest potential of -3.040 V vs. SHE. To achieve this goal, the formation of Li dendrites and mossy Li deposition, which cause poor cycle performance and safety issues, must be resolved.
To overcome this problem, many efforts have been devoted to suppress lithium dendrite growth. Recently, we demonstrated the possibility of using mechanically surface-patterned Li-metal for Li secondary batteries. In our previous work (J. N. Park et. Al), patterned Li-metal anode showed good cycle life at low current density cycling. However, during the repeated Li plating processes with high current density, the controlled surface is filled by granular forms of Li metal, which relatively increases the possibility of side reactions caused by decomposition of electrolyte as well as reduces suppressing effect of dendrite growth.
In this study, we applied a LiNO3 as an electrolyte additives on micro-patterned lithium metal to suppress the dendrite growth and mossy Li deposition. The effect of LiNO3 was studied by using galvanostatic cycling test, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and their electrochemical properties are investigated in detail.
New Routes Towards High Energy, Low Cost and Fast-Charging Energy Storage Systems
Authors: Agostini Marco , Matic Aleksandar 
Published: February 2020

The rapid growing of electronic technologies as well as electric vehicles requires the development of new, higher energy and environmental friendly storage systems. In this scenario ideal candidates are the batteries systems and in particular those based on the electrochemical process of lithium, thanks to long calendar-life and to favorable design. However, although this technology is adequate for the consumer electronics market, it has some serious shortcomings when considering implementation in electric vehicles or in grid energy storage applications. In particular limiting factors are related to the low energy density of LiCoO2 cathodes and graphite anodes. Additionally, the use of Cu as current collector at the anode and also the increasing cost and reducing availability of Co push the research to the development of alternative chemistries exploiting materials environmental friendly, with higher energy density and reduced cost
1-3
.
In this contribution, we present new strategies to improve the energy density, increase the safety level and reduce the cost of energy storage systems based on Li process.

References

(1) B. Scrosati, J. Garche, J. Power Sources.
195, 2419-2430, (2010).
(2) Y. Yang, G. Zheng, Y. Cui, Energy Environ. Sci.
6, 1552-1558, (2013).
(3) Whittingham, M. Chem. Rev.
104, 4271-4302, (2004).
Water-Gas Shift Reaction Activity of Pt Nanoparticles Hybridized with Metal-Organic Frameworks
Authors: Ogiwara Naoki , Kobayashi Hirokazu , Kitagawa Hiroshi 
Published: February 2020

Metal-organic frameworks (MOFs) with nanopores have been attracted much attention as a platform for absorbing guest molecules and the absorbed molecules in MOFs exhibit the unique physicochemical properties different from those of free gaseous molecules.1 However, there is poor understanding of how the confined guest molecules affect chemical reactions. To uncover the insight, we designed a hybrid material based on MOFs and metal nanoparticles (NPs), where MOFs provide absorbed molecule as a reactant and metal NPs work as a catalyst.
At first, we prepared 9 nm Pt NPs using a liquid phase reduction method.2 Then, the obtained Pt NPs were coated with a thermally stable Zr-based MOF (UiO-66)3 by a solvothermal method in the presence of ZrCl4 and terephthalic acid. Transmission electron microscopy (TEM) image revealed that the UiO-66 completely covers the Pt surface (Pt@UiO-66). For comparison, we also prepared Pt on UiO-66, where Pt NPs are located on the surface of UiO-66, by mixing Pt NPs and pristine UiO-66 in DMF and centrifuging them. We investigated water-gas shift reaction4 activity of Pt@UiO-66 and Pt on UiO-66 by using a fixed bed flow reactor. Both Pt@UiO-66 and Pt on UiO-66 exhibited higher CO conversion than Pt on ZrO2, demonstrating that the presence of the UiO-66 hybridizing causes an enhancement in the catalytic activity. Interestingly, the activity of Pt@UiO-66 was much higher than that of Pt on UiO-66, demonstrating that the UiO-66 coating enhanced the activity. The detail mechanism on the enhanced activity is also discussed.
References

X. Kong, J. R. Long, J. A. Reimer et al., J. Am. Chem. Soc., 2012, 134, 14341.

C. Tsung, G. A. Somorjai, P. Yang et al., J. Am. Chem. Soc., 2009, 131, 5816.

L. H. Cavka, K. P. Lillerud et al., J. Am. Chem. Soc., 2008, 130, 13850.

H2O + CO → H2 + CO2

Figure 1
A Dipolar Surface Mounted Metal-Organic Framework (SURMOF): Basis for Sensor Applications
Authors: Gies Joshua , Füser Matthias , Bolte Michael , Terfort Andreas , Kind Martin 
Published: February 2020

In a cooperation within the COORNETs SPP, we aim to develop novel sensor systems based on dielectric and ferroelectric surface-mounted metal-organic frameworks (SURMOFs). To this end, we synthesize Kitagawa-type metal-organic frameworks, M2L2P (M= metal, L= linker, P= pillar) [1]. For our project, either the linker or the pillar molecules need to comprise a rotatable dipole moment perpendicular to the molecular axis.
We will report on our recent results on the system [Cu2(bdc)2(dpym_btd)] (bdc2- = 1,4-benzenedicarboxylate, dpym_btd = 4,7-di(pyridine-4-yl)-2,1,3-benzothiadiazole). We have synthesized bulk MOF material using a solvothermal procedure, followed by characterization via X-ray crystallography.
A layer-by-layer (LbL) approach was applied to deposit [Cu2(bdc)2(dpym_btd)] as a SURMOF on a functionalized Au(111) model surface. Several LbL parameters were optimized, such as template chemistry, deposition temperature and concentration of the precursors.
Reference:
[1] Kondo, T. Okubo, A. Asami, S. Noro, T. Yoshitomi, S. Kitagawa, T. Ishii, H. Matsuzaka, K. Seki, Angew. Chem. Int. Ed.
1999, 38, 140-143.

Figure 1
(Invited) Fabrication of MOFs Membranes for Molecular Separation
Authors: Qiu Shilun , Xue Ming 
Published: February 2020

Metal–organic framework (MOF) materials, which are constructed from metal ions or metal ion clusters and bridging organic linkers, exhibit regular crystalline lattices with relatively well-defined pore structures and interesting properties. As emerging inorganic and organic hybrid materials, MOF materials are very appealing to be assembled into MOF membranes for separation and catalysis applications because their pores can be rationally controlled by the interplay of both inorganic metal ions and organic linkers, and their pore surfaces can be readily functionalised through a variety of approaches.[1,2] The ability to rationally tune the structure of the materials may create unique interactions with guest molecules and thus achieve unusual chemicophysical properties in adsorption and separation.
Reference:

L. Qiu, M. Xue and G. S. Zhu, Chem. Soc. Rev., 2014, 43, 6116.

X. Kang, M. Xue, L. L. Fan, L. Huang, L. J. Guo, B. L. Chen, S. L. Qiu, Energy Environ. Sci, 2014, 7, 4053.
Modeling Water Management and Carbon-Dioxide Contamination Effects in Anion-Exchange Membrane Fuel Cells
Authors: Gerhardt Michael R. , Pant Lalit M. , Shiau Huai-Suen , Weber Adam Z. 
Published: February 2020

Anion-exchange membrane fuel cells (AEMFCs) offer a potential advantage over their traditional proton-exchange membrane counterparts in that AEMFCs can operate with non-precious metal catalysts [1]. Recently, high-power operation of AEMFCs has been demonstrated in laboratory-scale cells [2]. The performance of AEMFCs, however, can be highly sensitive to small changes in relative humidity due to the critical role of water in both the alkaline oxygen reduction reaction and in hydrating the membrane. Additionally, carbon-dioxide absorption and conversion to carbonate anions reduces membrane conductivity and worsens fuel-cell performance.
In this work, we use our previously developed two-dimensional model [3] to illustrate and explore the effects of membrane and ionomer properties, relative-humidity changes, and absorption of carbon dioxide on cell performance. We model local current density changes in large-area cells by stepping the two-dimensional model along the flow channel, updating it at each step to account for changes in gas concentration and relative humidity. Finally, we show how performance limitations from carbon-dioxide absorption, flooding, and dry-out could be alleviated through changes in operating parameters or ionomer properties.

Acknowledgements

The work was funded by the Assistant Secretary for Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, of the U.S. Department of Energy under contract number DE-AC02-05CH11231. We thank Bryan Pivovar and the members of the Fuel Cells group of the National Renewable Energy Laboratory for helpful discussion and model validation data.

References

[1] J. R. Varcoe et al., “Anion-exchange membranes in electrochemical energy systems,” Energy Environ. Sci., vol. 7, pp. 3135–3191, 2014.
[2] D. R. Dekel, “Review of cell performance in anion exchange membrane fuel cells,” J. Power Sources, vol. 375, pp. 158–169, Jan. 2018.
[3] H.-S. Shiau, I. V. Zenyuk, and A. Z. Weber, “Elucidating Performance Limitations in Alkaline-Exchange- Membrane Fuel Cells,” J. Electrochem. Soc., vol. 164, no. 11, pp. E3583–E3591, 2017.
Fuel Cell Management System: PEMFC Lifetime Optimization by Model Based Approach
Authors: Piffard Maxime , Naiff da Fonseca Ramon , Massioni Paolo , Bideaux Eric , Gerard Mathias 
Published: February 2020

The estimation and increase of the lifetime of PEMFC fuel cell under dynamic conditions is one of a major challenge about PEMFC. Increasing the durability of the fuel cell must be treated by both the development of new material and design but also by optimal strategies and management of the operating conditions of the fuel cell. Indeed, the different irreversible degradation mechanisms in the MEA (Membrane Electrode Assembly), as the platinum dissolution, Ostwald ripening, carbon support corrosion and chemical membrane degradation, and reversible degradation mechanisms (platinum oxidation, nitrogen stratification, liquid water management) are strongly coupled to the local conditions into the MEA. Moreover, the local conditions into the MEA depend on the material properties but also on the dynamic operating conditions of the fuel cell stack. The strong coupling of the different phenomena can be solved by numerical simulations and an optimum can be found for performance and durability.
In this approach, the lifetime of the fuel cell is optimized by a dynamic management of the operating conditions of the fuel cell stack. Indeed, for a same desired power, different set of operating conditions (pressure, temperature, current and stoichiometry) can deliver the same power. Constraints to manage the liquid water inside the fuel cell is also added. A unique cost function, based on a model approach, is built to optimize the fuel cell performance (including compressor consumption and cooling) and the durability of the MEA (irreversible degradations with platinum dissolution and chemical degradation of the membrane and reversible degradation with water management).
The different laws used are based on physical models. Their expressions are reduced to be analytical and directly solved. The operating conditions management algorithm is built off-line. It defines the optimum operating conditions of the fuel cell stack (anodic pressure, cathodic pressure, stack temperature, current, air stoichiometry and hydrogen stoichiometry) as a function of the desired power and some fuel cell internal states (water content inside the membrane, water vapor, State of Health SoH). These internal states can be estimated by state observers. The operating conditions management algorithm is validated within a multi-physics fuel cell model. The simulations on a dynamic power cycle show that the degradation rate can be divided by two and compressor consumption also reduced. Moreover, the constraints on the water inside the fuel cell guarantee a correct behavior of the fuel cell stack. The algorithm can also be easily adapted to the fuel cell SoH (State of Health).

Figure 1
The Effect of a Turbulence Grid on the Temperature Distribution in an Air-Cooled Proton Exchange Membrane Fuel Cell – a Modelling Study
Authors: Pløger Line Justesen , Fallah Rasheed , Al Shakhshir Saher , Berning Torsten , Gao Xin 
Published: February 2020

Air-cooled proton exchange membrane fuel cells are becoming increasingly attractive as an alternative power source for a large number of applications including material handling, telecom back-up power and more recently unmanned aerial vehicles. A salient advantage is their simplicity of operation because they do not require a secondary coolant loop, which greatly simplifies their control. A recognized problem is the thermal management of the electrochemical reaction has the tendency to overheat the stack at low current densities around 0.4 A/cm2 e.g. in case of a Ballard 1020 ACS stack. Our research group has recently found out that, the biggest problem in the thermal management is the heat transfer into the air inside the cathode channels, and we have proposed to place a turbulence grid before the air inlet with the goal to induce a mixing effect in this otherwise laminar flow and thereby improve the heat transfer resulting in better thermal management of the electrochemical reaction. First experiments have resulted in an increase in the limiting current density by 20 % along with an increase in power density by more than 30% and a decrease in hydrogen consumption by more than 20 % at the desired operating point.
The work presented here summarizes a modeling analysis employing computational fluid dynamics with the commercial solver Fluent 18. The goal of this work was to gain additional understanding as to the effect of such a turbulence grid placed before the cathode inlet and ideally to optimize the key parameters such as the detailed grid geometry, the distance between the turbulence grid and the flow channel, and the cathode flow channels themselves. In our model, different types of grids were placed in varying distances before the cathode inlet. Only a single channel on the cathode side is modeled, and the airflow rate was calculated out of the desired stoichiometric flow ratio of 50 and a current density of 0.4 A/cm2. Inside the cathode flow channel a heating term that accounts for the waste heat generated by the electrochemical reaction was implemented. The numerical results summarize the distribution of the turbulence intensity induced by the grid, the turbulence dissipation rate, the velocity distribution and, most importantly, the predicted temperature distribution inside the cathode flow channel and the bipolar plate. The single most important result was the predicted maximum temperature inside the fuel cell, and the goal was to improve the heat transfer rate and reduce this temperature so that the fuel cell may be operated at a higher current density. The modeling results will be verified with experiments where the fuel cell performance and the temperature in a pre-determined position will be measured for a variety of turbulence grids printed with the 3D printer.

Figure 1
Heuristic and Nonheuristic Methods for the Design of Proton Exchange Membrane Fuel Cells
Authors: Lamb James , Andrei Petru 
Published: February 2020

There has been much work on the numerical optimization of proton exchange membrane fuel cells (PEMFCs). The optimization techniques can be divided in heuristic and non-heuristic techniques.
Heuristic techniques (such as genetic algorithm, particle swarm optimization, differential evolution, simulating annealing, harmony search, memetic algorithms, bird mating optimization, and artificial immune system) usually use stochastic methods to identify an optimal solution, which require a large number of device simulations and compromise the accuracy of the solution. The computational cost of heuristic techniques limit their application to a small number of variables (usually under ten), and can generally be applied to simplified models.
In contrast, non-heuristic techniques (such as line search and trust-region methods, the Nelder-Mead method, the Powell algorithm, steepest descents, conjugate gradient methods, Newton and quasi-Newton methods, and linear and quadratic programming) are deterministic and often require computing or approximating the gradient of the objective function [1-4]. Usually these techniques have local convergence and their rate of convergence can be improved by using the Hessian matrix or other second-order derivatives, evaluating the gradient more accurately, or taking advantage of the particular functional form of the objective function. Depending on whether the gradient function can be evaluated or not, as well as on the accuracy with which the first and higher order derivatives can be computed, non-heuristic techniques usually require between a few and 100 iterations to optimize the objective function, while the total number of variables to be optimized could be larger than 105.
In this work we compare heuristic and nonheuristic methods and present a gradient-based technique for the optimization of the catalyst distribution in PEMFCs using finite element models. We demonstrate a non-heuristic technique to determine optimum platinum distribution in the catalyst layer (CL) by allowing the catalyst amount to vary independently at each not inside the CL. Therefore, the total number of finite elements in the CL, in this work, is larger than 104; however, the technique could be extended to systems with even more elements. Optimization is performed by first computing a catalyst sensitivity function, which is the gradient of the objective function with respect to the mass of catalyst at each location in the CL; then an adjoint space technique is employed to evaluate the catalyst sensitivity functions at each node in the finite element discretization. Cell performance is evaluated and compared for the optimized and non-optimized PEMFCs.
References
[1] F. C. Cetinbas, S. G. Advani and A. K. Prasad, Journal of Power Sources, 250, 110 (2014).
[2] J. Lamb, G. Mixon and P. Andrei, Jour of the ECS, 164, E3232 (2017).
[3] P. Andrei and L. Oniciuc, Jour of Appl. Physics, 104, Art. No. 104508 (2008).
[4] P. Andrei and L. Oniciuc, Jour of Comp. Elec., 7, 111 (2008).

Figure 1
Change of Preferential Liquid Breakthrough Pathways in PEMFC Gas Diffusion Layers: Evidence of Pressure-Induced Dynamic Transport
Authors: Chevalier Stephane , Josset Christophe , Auvity Bruno 
Published: February 2020

Polymer Electrolyte Membrane (PEM) fuel cells are considered as promising clean sources for automotive applications. A key challenge to reduce the cost of this technology is to increase the power density by operating PEM fuel cells at high current densities. One strategy is to improve the 3D structure of the gas diffusion layer (GDL) located between the channel and the catalyst layer (CL). At the cathode side, this GDL is used to evacuate the liquid water toward the channel while providing access to the oxygen to the CL [1]. Although innovative GDL structures have been proposed, a better understanding of the liquid water would help to design better GDL. In particular, few works have investigated the liquid water transport after several hours of steady state fuel cell operating conditions although changes in liquid water preferential pathway have been observed [2]. Such changes are not predicted in theory, and a physical explanation of these mechanisms is still required.
In this presentation, we investigate ex situ the change of liquid water preferential pathways through PEM fuel cell GDLs. Liquid water breakthough from the GDL to the fuel cell channels is mimicked using a microfluidic PDMS device with embedded GDLs. Liquid water is injected through the GDL to the microchannel, and changes in liquid water pathways are observed after several hours of operations. These changes in liquid water pathway are attributed to the dynamic of droplet eruption in fuel cell microchannel. To validate this assumption, a small capillary network with is built. It is shown that after the liquid water breakthrough, the pressure variation due to the growth of the water droplets in the microchannel enables the liquid water to invade smaller capillaries which at the end can change the preferential path. The experimental observations reported in this work show that the invasion percolation theory can be used to predict the preferential pathway at the onset of the liquid water breakthrough, but pressure-induced dynamic transport [3] due the water droplet eruption in the channel has also to be taken into account to predict the preferential pathway after long time of fuel cell operation.

References

[1] T. Yoshida, K. Kojima, Toyota MIRAI Fuel Cell Vehicle and Progress Toward a Future Hydrogen Society, Interface Mag. 24 (2015) 45–49.
[2] Z. Lu, M.M. Daino, C. Rath, S.G. Kandlikar, Water management studies in PEM fuel cells, part III: Dynamic breakthrough and intermittent drainage characteristics from GDLs with and without MPLs, Int. J. Hydrogen Energy. 35 (2010) 4222–4233.
[3] S. Chevalier, C. Josset, B. Auvity, Fluid dynamic breakthrough in two connected capillaries: From stationary to oscillating state, Phys. Fluids. 29 (2017) 102102.