bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Changes and Impedance Rise in Li4Ti5O12 - LiNi0.5Co0.2Mn0.3O2 Cells
Authors: Sahore Ritu , Tornheim Adam , Bareno Javier , Zhang Zhengcheng , Bloom Ira
Published: February 2020

LiNi0.5Co0.2Mn0.3O2(NCM 523) is a promising cathode material for lithium-ion batteries due to its higher capacity, stability, and lower cost compared to LiCoO2, the other commonly used layered oxide.  However, the high operating voltage of NCM523 (> 4.3V vs. Li/Li+) makes conventionally used electrolytes unstable. Their continuous electrochemical degradation at the electrodes surface adds to impedance rise, which is a major contributor to rapid capacity fade. High temperature conditions can accelerate these processes. Despite its practical and academic interest, there is no coherent model of cell degradation mechanisms responsible for the observed impedance changes.

In this work, lithium-ion cells consisting of an NCM523 cathode and a Li4Ti5O12(LTO) anode were prepared and subsequently aged at different temperatures and for different times after galvanostatically charging to a final hold potential of 4.6V vs. Li/Li+. Impedance increase and oxidation current were monitored as a function of aging time, hold voltage, temperature, and electrolyte additive concentrations. After aging, the cells were disassembled and chemical changes in the NCM523 electrode are characterized using a combination of techniques (including XPS, IR, and LC-MS) and correlated to the previously measured oxidation current and impedance increase.

 

Acknowledgement

The submitted issue has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-Eng-38 with the U.S. Department of Energy.

The U.S. Government retains for itself, and others acting on its behalf, a paid-up, non-exclusive, irrevocable, worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
Optimization of Electrolytes for Si-Containing Full Cell
Authors: Chevrier Vincent L , Petibon Remi , Aiken Connor , Krause Larry J , Jensen Lowell , Xiao Ang , Le Dinh Ba , Eberman Kevin W , Dahn Jeff R
Published: February 2020

Introduction

The Si/electrolyte interface is increasingly recognized as being a key factor in the successful implementation of Si-based materials in Li-ion batteries. Si-based negative electrode materials undergo massive volume changes during cycling. Pure Si expands by approximately 280% while 3M’s active/inactive Si alloys expand on the order of 135%. The expansion and contraction of Si has important consequences on the surface stability of these materials. This work will focus on the combined impact of material design and electrolyte choices on cell performance.

Results and Discussions

The 3M Si alloy is compared to pure Si in EC/EMC 3/7 + 10% FEC. Cross section SEM images are taken after 100 cycles in a half cell. While the 3M alloy shows a discernible SEI on distinct particles, the pure Si has dramatically expanded in size and completely lost its particle morphology. The impact of electrolyte choice on the surface morphology of the 3M Si alloy is then explored across a range of electrolytes compositions using cross section SEM images after 100 cycles.

Further testing is performed in 200 mAh pouch cells (Lifun), with a LiCoO2 positive electrode, a Si-alloy/graphite negative electrode, and approximately 3 mAh/cm2 of reversible capacity. In order to understand the impact of electrolyte composition as well as failure mechanisms, cells were studied by long term cycling, ultrahigh precision cycling, post-cycling gas chromatography/mass spectroscopy (GC/MS) of the electrolyte, in-situ volume measurements, and electrochemical impedance spectroscopy.

Fluorethylene carbonate (FEC) has long been recognized as an important electrolyte component for Si-containing full cells. GC/MS studies are used to study the consumption of FEC with cycle number as well as changes in electrolyte composition. FEC is found to be preferentially consumed relative to other electrolyte solvents and its depletion is found to generally cause sudden failure. A hierarchy of reactivity of electrolyte solvents is established.

An electrolyte additive in the new product introduction process at 3M will be presented. This additive is found to help delay sudden failure as well as suppress FEC gassing.

Conclusion

When implementing well-designed Si-based materials in commercially-relevant full cells, the electrolyte is a key parameter to be optimized. In this work, electrolyte optimizations lead to delayed sudden failure, suppressed gassing and reduced impedance growth. These findings suggest considerable gains are still attainable through further electrolyte optimizations, which will enable deeper penetration of Si-based materials into the marketplace.
Understanding Interfacial Resistance of Al-Substituted Li7La3Zr2O12 Solid Electrolyte
Authors: Chen Wei , Cheng Lei , Doeff Marca
Published: February 2020

Cubic garnet phases based on Al-substituted Li7La3Zr2O12 (LLZO) exhibit superior ionic conductivity and outstanding electrochemical stability against metallic lithium anode, making them promising solid electrolyte for next-generation rechargeable battery systems. However, high interfacial impedances of LLZO have prevented their wide applications. The interfacial resistances of lithium cells containing Al-substituted LLZO solid electrolytes are sensitive to their microstructures and histories of exposure to air. Air exposure of LLZO samples with large grain sizes results in dramatically increased interfacial impedances in cells containing them, compared to those with pristine large-grained samples. In contrast, a much smaller difference is seen between cells with small-grained pristine and air-exposed LLZO samples. A combination of soft X-ray absorption (sXAS) and Raman spectroscopy, with probing depths ranging from nanometer to micrometer scales, revealed that the small-grained LLZO pellets are more air-stable than large-grained ones, forming far less surface Li2CO3 under both short- and long-term exposure conditions. Surface sensitive X-ray photoelectron spectroscopy (XPS) indicates that the better chemical stability of the small-grained LLZO is related to differences in the distribution of Al and Li at sample surfaces. Density functional theory thermodynamic calculations show that LLZO can react via different pathways to form Li2CO3. These observations have important implications for the operation of solid-state lithium batteries containing LLZO because the results suggest that the interfacial impedances of these devices is critically dependent upon specific characteristics of the solid electrolyte and how it is prepared.
Layered P2-Nax[Mg, Ni, Mn]O2 Cathodes: What Are the Atomistic Effects of Cation Substitution?
Authors: Chen Hungru , Heath Jennifer , Islam M. Saiful
Published: February 2020

Layered sodium transition metal oxides such as Nax[Ni, Mn]O2 with P2 oxygen stacking structure are potential cathode materials for sodium-ion batteries. The main challenge is that they tend to show many plateaux in the charge-discharge profile, indicating numerous phase transitions resulted from sodium orderings, which has adverse effects on cyclability. Recently it has been reported that the substitution of non-redox active cations, such as Mg2+, Li+ and Zn2+, for transition metal ions results in smooth charge-discharge profile and improved rate performance. In this work, the P2-Nax[Mg, Ni, Mn]O2 system is investigated by both ab-initio and interatomic potential molecular dynamics simulations in order to understand the role of Mg2+ substitution. Na-ion diffusivities and migration barriers are simulated, and the atomistic effects of Mg2+ are discussed.
Innovative Oxygen Selective Membrane for Li-Air Battery Operating in Ambient Air
Authors: Amici Julia , Alidoost Mojtaba , Zeng Juqin , Francia Carlotta , Bodoardo Silvia , Trotta Francesco , Penazzi Nerino
Published: February 2020

The demand for high-energy storage systems is constantly increasing, as is the interest to explore alternatives to commercially available batteries. The rechargeable Li-air battery represents an exciting opportunity to design batteries that may satisfy some of the requirements of our future by coupling the light Li metal with the inexhaustible source of O2 of the surrounding air, resulting in high theoretical specific energy density. Currently, most of the researches on the Li-air battery comprise a cell fed with pure O2 allowing that way to maintain long-term operation, owing to the high O2 concentration free of contaminants. However, for many practical applications such as EV, air is the only viable option to supply the battery. In this context, moisture and gases other than O2 may cause side reactions and corrosion. Herein, we report a facile strategy to fabricate an effective oxygen selective membrane with poly(vinylidene fluoride co-hexafluoropropylene) (PVDF-HFP) via non-solvent induced phase separation, casted as a 240 micron thin sheets for cell protection in ambient air condition. The use of different additives helps enhancing the barrier properties as well as the membrane specificity toward O2. For instance, sacrificial silica nanoparticles (SiO2 NPs) were incorporated into the precursor solution to create a controlled alveolar-like structure inside the membrane. The membrane was loaded with polydimethylsiloxane (PDMS) under vacuum. Another kind of additive considered is the cyclodextrine. Indeed, thanks to their unique structure, cyclodextrines are able to form host-guest complexes with hydrophobic molecules such as our polymer matrix. Nanosponges based on cyclodextrines were prepared and added to the polymer precursor solution before membrane casting. The as prepared membranes showed higher oxygen permeability and lower water permeability. Galvanostatic charge-discharge cycling tests of a Li-air pouch cell in a potential/time controlled mode showed an outstanding cycling life superior to 1500h with more than 150 cycles.
Advanced Planar Li-S Batteries
Authors: Zhao Feng , Bi Zhonghe , Beacco David , Larsen Dennis
Published: February 2020

Ceramatec is developing new batteries that make use of a non-porous, high ion conductivity ceramic membrane employing a lithium-sulfur (Li-S) battery chemistry. Porous separators found in today’s batteries contain liquids that negatively impact cycle life. To address this, Ceramatec’s battery includes a ceramic membrane to help to hold charge while not in use. This new design would also provide load bearing capability, improved mechanical integrity, and extend battery life. Ceramatec will build and demonstrate its innovative, low-cost, non-porous membrane in a prototype Li-S battery with a smaller size and higher storage capacity than conventional batteries. The project progress will be updated.
Capillary Deposition of Binder-Free Lithium Sulfide-Carbon Composite in Three Dimensional Nickel Foam for High Performance Lithium-Sulfur Battery
Authors: Kaiser Mohammad Rejaul , Liang Xin , Liu Hua Kun , Dou Shi Xue , Wang Jiazhao
Published: February 2020

Lithium sulfide (Li2S), which has a theoretical capacity of 1166 mAh/g, is considered as a promising cathode material for the Li-S battery. The electrochemical performance of microsized Li2S is impaired, however, by its low electrical conductivity as well as first cycle high activation potential problem. In this work, microsized Li2S powder had been ball milled with different carbon sources to synthesize Li2S-C composites as well as to find the suitable carbon sources, which were then capillary-deposited in three-dimensional multi-layered Ni foam from a dioxolane-containing mixture to fabricate a binder-free Li2S-C composite cathode. A large amount of active material (~5 mg/cm2) was loaded in each cathode with the help of conventional capillary deposition method. Scanning electron micrographs show that the Li2S-C composite successfully fills the pores in the Ni foam through capillary action and maintains the integrity of the structure before and after cycling performance. High voltage (3.5V) 1st cycle charging was applied to activate the Li2S. Electrochemical performance testing shows that the capillary-deposited binder-free Li2S-C composite was successfully activated and showed excellent cycling performance along with superior rate capability. For further improvement of electrochemical performance, a single-walled carbon nanotube free-standing layer was inserted in between the cathode and the separator which inhibited longer chain polysulfide to travel from cathode to anode and minimized shuttle phenomenon thus improved the discharge capacity and the capacity retention.
Fuzzy Logic-Based Fault Prevention of the Battery System in Hybrid Electric Vehicle
Authors: Esfandyari Mohammad Javad , Esfahanian Vahid , Hairi Yazdi Mohammad Reza , Nehzati Hassan
Published: February 2020

Due to high energy and power density, lithium-ion batteries (LIBs) have become one of the most popular choices for electric vehicle (EV) and hybrid electric vehicle (HEV) applications. However, reliability and durability of LIBs are highly affected by the operational and environmental conditions. The Battery Management System (BMS) is responsible for guaranteed performance and safety of batteries. Typically, the battery system protection against current or voltage fault conditions is performed using a simple on/off command from the BMS to a power contactor. However, the sudden elimination of power due to transient current or voltage changes (e.g. vehicle launch or climbing a slope) reduces the amount of energy that can be delivered and in some cases may be dangerous for the components in connection with the batteries. This paper presents the design of a closed-loop fuzzy-based control system to achieve maximum performance of the battery with regard to driving conditions such that safe operation of the battery is ensured. To do so, battery voltage or current is limited using a control input from a fuzzy controller implemented in the BMS. The vehicle Central Control Unit (CCU) corrects the traction motor torque command according to the control input received from the BMS in order to maintain battery safe operating region. This way, the battery current and voltage is limited before reaching the fault conditions, thereby improving the durability of the battery and preserving its life. Performance of the designed control system is evaluated in various driving regimes using a Hardware-in-the-Loop (HiL) test bench. Results show the efficacy of the designed control system toward the prevention of voltage and current fault conditions.
A Study of Surrogate Li-Ion Cell Fabrication and Characterization for Electric Vehicle Applications
Authors: Kwon OuJung , Miller Ted J. , Drews Andy , Yang Xiao Guang
Published: February 2020

Ford has invested $2.1 million to open a new joint Li-ion battery fabrication and characterization laboratory at the Univeristy of Michigan. This prototyping laboratory enables multiple scale cell manufacturing and high process quality that is feasible to scale up, and evaluation of battery chemistries and electrode design while reducing the risk and cost. State-of-the-art manufacturing methods will be used to build surrogate cells that replicate the performance of full-scale production batteries, allowing for faster implementation in future production electrified vehicles. More details will be presented at the meeting.
Ultrathin and Uniform Carbon Coating on Active Materials Using Liquid CO2 As a Coating Solvent
Authors: Hwang Jieun , Kim Jaehoon
Published: February 2020

Some of cathode and anode active materials (e.g., LiFePO4, Li4Ti5O12, Li2FeSiO4, TiO2, MoO2) exhibit inherently low electronic conductivities and low ionic conductivities; thus, these materials typically suffer from poor electrochemical performance. The reduction of particle size to a nanoscale dimension to enhance lithium ion diffusivity and carbon coating to increase electronic conductivity are the most widely used strategies to improve the performance of the potential active materials. Incorporation of too much carbon content, thick carbon layer coating, and non-uniform carbon coating on individual particles can also deteriorate energy density and battery performance. The complete, uniform, and thin carbon layer coverage ensures that the particles receive electrons from all directions and the electrons penetrate easily through the carbon layer, resulting in low polarization and high-rate performance. Herein, the use of liquid carbon dioxide (l-CO2) for uniform and ultrathin carbon layer coverage on highly porous LiFePO4 and MoO2 particles is discussed. The extremely low surface tension and the low viscosity associated with l-CO2 make it an excellent coating solvent for uniform and ultrathin carbon layer formation on the highly porous active materials. In addition, the carbon content in the range of 1-10 wt% can be easily controlled by adjusting process parameters such as solution concentration or evaporation velocity. The hierarchically porous MoO2 microspheres are synthesized in supercritical methanol without using any surfactants or structure-directing chemicals. The highly porous LiFePO4 particles are synthesized using a co-precipitation method. The MoO2 and LiFePO4 particles exhibits hierarchically porous nano/micro structure, in which primary particles with 30-65 mn size are loosely aggregated and form secondary spheres with 0.5-10 mm size. Owing to the low viscosity and low surface tension of l-CO2, the coating solution is penetrated into the pores of the particles and uniform and ultrathin carbon layer is covered on the primary particles. The thickness of carbon layers were in range of 0.8-2.0 nm by adjusting the carbon precursor concentration in l-CO2. The TEM analysis on the cross-sectional area of the particles shows that the uniform incorporation of the carbon layer on the whole surface of the micron-sized secondary particles. The carbon-coated LiFePO4 exhibits ~108.6 mAh g-1 at a high charge-discharge rate of 30 C. In addition, after 1000 cycles of 10 C, ~ 85% of an initial capacity is maintained. The carbon-coated MoO2 exhibits enhanced high-rate performance and cell stability.

Figure 1
Influence of Synthesis, Dopants and Cycling Conditions on the Cycling Stability of Lithium Nickel Manganese Oxyfluoride Spinels
Authors: Höweling Andres , Geßwein Holger , Binder Joachim R.
Published: February 2020

Higher capacities and energies are needed in order to achieve widespread acceptance of Li-ion batteries as power sources in electric vehicles. In principle, Li-ion batteries offer two possibilities to achieve higher specific energies. Since the batteries’ energy is determined by the operational voltage and the active materials capacity, one could improve either the capacity of the active materials or the operating voltage of the cell.

Both approaches are pursued by many research groups. Higher capacities can for example be achieved with Li-rich layered oxides, where the use of more than 1 Li in the active material can considerably improve the capacity. The operational voltage is mainly determined by the potential of the cathode material vs. Li-metal. Therefore high voltage cathode materials

(e.g. LiMxMn2-xO4, with M = e.g. Ni, Co) are used.

However both approaches suffer from different limitations and problems. The need for balancing and the commonly relatively low mean voltages of ca. 3.5 V vs. Li+/Li0
reduce the gain in specific energy for materials with high capacities. On the other hand, the use of high voltage materials leads to unwanted site reactions and severe capacity fade when applied with a graphitic Anode. This is because the cells are operated above the stability window (ca. 1.0 – 4.3 V vs. Li+/Li0 in the presence of transition metal ions like Ni4+ and Mn4+) of current organic electrolytes. Furthermore the theoretical capacity of 147 mAh g-1 for the LiNi0.5Mn1.5O4 high voltage spinel is relatively low.

The shortcomings of the high voltage spinel can be overcome, when metallic lithium is used as the anode material. Not only the cycling stability is significantly improved but also the use of metallic lithium leads to the ability of cycling of 2 Li eq. per cycle, since the spinel lattice is able to host 2 Li eq. This is leading to a theoretical capacity of 294 mAh g-1 and therefore a theoretical specific energy of ~1030 Wh kg-1 can be reached when the cell is cycled between 2.0 and 5.0 V vs. Li+/Li0.

Unfortunately, the cycling of 2 Li eq. is leading to a severe capacity fade due to a phase transition from cubic to tetragonal in the low voltage region associated with material degradation.

In this work doping with transition metal ions is used to improve capacity retention when cycling between 2.0 and 5.0 V vs Li+/Li0. Initial capacities and stabilities are directly dependent on synthesis conditions and doping elements. The goal is to achieve a high stability of the material at a low tradeoff of capacity. Therefore different combinations of doping elements are used and tested at different cycling conditions. In addition to the transition metal ions, fluorine doping is also used to increase cycling stability.

The influence of different synthesis, doping and cycling conditions on cycling stability and capacity retention are discussed.
Improved Adhesion and Electrochemical Properties of Silicon/Carbon Composite Anodes By Using a Co-Polyimide Binder
Authors: Kim Kyuman , Choi Jaecheol , Cho Kuk Young , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Silicon (Si) is a promising anode candidates due to high theoretical capacity of 3500 mAh g-1, which is approximately 10 times higher than the capacity of conventional graphite anodes. However, Si anodes have not been widely introduced into commercial lithium-ion batteries (LIBs), because they experience large volume expansion (~400%) during charge-discharge cycling. In order to alleviate this expansion during Li+insertion and extraction, the choice of binder for holding all of the components in the Si anode is very important. Although polyvinylidene fluoride (PVdF) has been widely utilized as a polymeric binder for commercialized LIBs over decades, lots of previous works have proved that PVdF could not provide the Si anodes with sufficient physical property to keep their original anode structure. To overcome the limitation of PVdF, a number of researchers have proposed new polymeric binder such as polyacrylic acid (PAA) [1], alginate [2] and polyimide (PI).[3-4] However, there is no LIBs adopting the only Si for their anode due to small but continuous electrolyte decomposition and pulverization for a long cycle life.

Herein, we fabricate silicon/carbon (Si/C) composite anodes with highly adhesive and soluble co-polyimide (P84) binder. Their adhesion and electrochemical properties are evaluated by comparing conventional PVdF binder system. In addition, the loading level and density of electrodes are also changed to find an optimum binder contents or design parameters. 

Acknowledgements

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977).

References

 [1] Magasinski, A.; Zdyrko, B.; Kovalenko, I.; Hertzberg, B.; Burtovyy, R.; Huebner, C. F.; Fuller, T. F.; Luzinov, I.; Yushin, G., Toward Efficient Binders for Li-Ion Battery Si-Based Anodes: Polyacrylic acid. ACS Appl. Mater. Interfaces 2010, 2, 3004-3010.

 [2] Ryou, M. H.; Kim, J.; Lee, I.; Kim, S.; Jeong, Y. K.; Hong, S.; Ryu, J. H.; Kim, T. S.; Park, J. K.; Lee, H., Mussel‐Inspired Adhesive Binders for High‐Performance Silicon Nanoparticle Anodes in Lithium‐Ion Batteries. Adv. Mater. 2013, 25, 1571-1576.

[3] Choi, J.; Ryou, M.-H.; Son, B.; Song, J.; Park, J.-K.; Cho, K. Y.; Lee, Y. M., Improved High-Temperature Performance of Lithium-Ion Batteries through Use of a Thermally Stable Co-Polyimide-Based Cathode Binder. J. Power Sources 2014, 252, 138-143.

[4] Choi, J.; Kim, K.; Jeong, J.; Cho, K. Y.; Ryou, M.-H.; Lee, Y. M., Highly Adhesive and Soluble Copolyimide Binder: Improving the Long-Term Cycle Life of Silicon Anodes in Lithium-Ion Batteries. Appl. Mater. Interfaces 2015, 7, 14851-14858.

Figure 1
Reduction of Charge and Discharge Polarization By Cobalt Nanoparticles-Embedded Carbon Nanofibers for Lithium-Oxygen Batteries
Authors: Kim Yun-Jung , Lee Hongkyung , Lee Dong Jin , Noh Hyungjun , Lee Jinhong , Park Jung-Ki , Kim Hee-Tak
Published: February 2020

The battery material community has a persistent consensus that Li–O2 batteries would be the most promising next generation batteries due to its extraordinarily high energy densities; from a practical view point, at least 2~3 times higher than those of conventional lithium ion batteries (LIBs).[1] However, Li–O2 batteries suffer from their chronically low round trip efficiency due to poor reversibility of lithium peroxide, Li2O2, which is main product of discharged Li–O2 batteries. This truly originates from its intrinsically poor electron and ionic conductivity.[2] Therefore, the reduction of charging overpotential is in urgent need for economical progress of Li–O2 batteries.

In an effort to achieve high round trip efficiency, recent studies have attracted great attention that the charge behaviors of Li–O2 cells can be manipulated by controlling the phase structure and morphology of Li2O2 formed during discharge. In particular, at a low current density, the large toroidal structured, crystalline Li2O2 was primarily formed. In contrast, the formation of film-like amorphous Li2O2 is favored at high current density. [3,4] Owing to its structural advantages of enhanced ionic and electronic transport[5], the oxidation of less crystalline Li2O2 is more efficient, resulting in significant decrease on charge overpotential. Consequently, the controlling phase and morphology of Li2O2 is an effective strategy for manipulating charge behavior of Li–O2 cells.

As a possible approach for controlling Li2O2, we designed an effective electrochemical catalyst of oxygen reduction reactions in Li-O2 batteries, a cobalt nanoparticles (Co NPs) embedded carbon nanofibers (Co-CNFs). As a result, embedded Co NPs leads to the formation of uniform film-like amorphous Li2O2, and thus, the Li–O2 battery employing the Co-CNF provides a round trip efficiency of > 77% and extends cycling stability by more than 6 times in comparison with a CNF electrode. These change of Li2O2 mainly is derived from a charge delocalization originating from the electron transfer from Co NPs to C-atoms. According to HSAB theory, highly concentrated Li+ ions near electrode resulting from the preferable interaction with Co-CNFs could lead to the rapid precipitation of Li2O2 and prevent the crystallization of Li2O2. The findings suggest a novel electrode design strategy of combining inexpensive metal and carbons for modulating the phase of discharge product.

References

[1] Nat. Mater. 2012, 11, 19-29

[2] J. Phys. Chem. Lett. 2013, 4, 93−99

[3] J. Am. Chem. Soc, 2013, 135, 15364−15372

[4] Energy Environ. Sci., 2013, 6, 1772

[5] Chem. Mater, 2014, 26, 2952−2959
Modeling of Lithium Ion Battery Using Modelica and Scilab/Xcos
Authors: Arianto Sigit , Yuwono Rietje Yunaningsih , Prihandoko Bambang
Published: February 2020

Lithium ion battery is widely accepted as the better choice among secondary batteries available since it has high power and energy density. Its applications are usually in portable electronics, hybrid electric vehicle, electric vehicle, and energy storage in renewable energy plant such as solar cell, wind turbine, etc. Regardless of its applications, modeling lithium ion battery is very necessary so the model can be used to find out the batteries’ behaviors through simulation before the systems are built. Moreover, the model are also used to extract run-time parameters that are very important in keeping the system safe and efficient such as state of charge (SOC), state of health (SOH), etc. In this research, a lithium battery model was developed using Modelica standard modeling language which was implemented using Scicos graphical language programming that supports Modelica. Scicos used in this research was actually Xcos that is a variant of Scicos which is embedded in Scilab. Equivalent circuit model used in modeling the battery was Double Polarization (DP) model. DP model consists of open circuit voltage Voc, internal resistance Ri, and two parallel RC circuits. The parameters of the battery were extracted using Hybrid Power Pulse Characterization (HPPC) testing. In this experiment, the Double Polarization (DP) electrical circuit model was used to describe the lithium battery dynamic behavior. The results of simulation of the model were validated with the experimental results.
In Situ and Ex Situ NMR Studies of High-V Li Cathode Materials
Authors: Hu Yan-Yan , Feng Xuyong , Li Xiang , Chien Po-Hsiu , Rose Alyssa
Published: February 2020

Developing high-capacity, high-power, and low-cost cathodes for PHEV and EVs has been an important endeavor in recent years. Lithium- and Manganese-rich cathodes have attracted major research and development efforts. Major obstacles to address include structure (both surface and bulk) stabilization, hysteresis, and voltage fade.  Our research effort in this area focuses on understanding the fundamental chemistry related to those obstacles and designing mitigation strategies to improve the performance of high-V cathodes for rechargeable LIBs.

Solid-state NMR has its unique advantages over other techniques in investigating functional light elements (e.g., Li, Na, H, O). In particular, in situ NMR is capable of catching transient processes. In situ
7Li NMR was employed to monitor the intercalation and de-intercalation of Li in important rechargeable battery systems and to help illustrate the effects of ion migration on the bulk and surface structures. The new in situ NMR probehead design provides convenient connections to battery electrodes, cancellation of noise pickup, and a variable temperature range of -50-100oC, which is helpful to evaluate the temperature-dependence of the battery performance.  Ex situ
17O MAS NMR experiments have also been employed for the first time to directly probe O migration and loss over extended cycling. Chemical surface modifications, bulk composition variation, and new synthesis methods have been applied to improve battery performance.

Figure 1
Improved Corrosion Resistance of AA2024 Alloys through Hybrid Organic-Inorganic Sol-Gel Films Modified with Piperazine
Authors: Jiménez-Morales Antonia , Carbonell Diogenes , Montoya Rodrigo , Gelling Victoria J. , Galvan Juan Carlos
Published: February 2020

Hybrid sol-gel coatings were prepared by using mixtures of γ-methacryloxypropyltrimethoxysilane (MAPTMS) and tetramethylorthosilicate (TMOS) as organopolysiloxane precursors and piperazine as a corrosion inhibitor [1]. The sol-gel films were characterized by using Fourier transform infrared spectroscopy (FTIR), liquid state Si liquid-state nuclear magnetic resonance spectroscopy (29Si NMR) and viscosity measurements. The corrosion performance of the resulting coatings was analysed by using Global and Local Electrochemical Impedance Spectroscopies (EIS, LEIS). The study shows that these new coatings have promising anticorrosive properties when they are used for the corrosion protection of AA2024-T3 alloys in contact with NaCl aqueous solution.

The incorporation of piperazine additionally results in more effective barrier proprieties and improved corrosion protection of AA2024-T3 alloys acting firstly as a catalyst for Si-OH condensation during the polymerization of the organopolysiloxane network increasing film thickness and secondly as a metal corrosion inhibitor of the metal substrate in the base of pores of the sol-gel film.

Acknowledges:

This work was supported by the Ministry of Economy and Competitiveness of Spain (Project MAT2015-65445-C2-1-R) and Comunidad de Madrid (Project S2013/MIT-2862-MULTIMAT-CHALLENGE).

References

D.J. Carbonell, A. García-Casas, J. Izquierdo, R.M. Souto, J.C., Galván, A. Jiménez-Morales, Scanning electrochemical microscopy characterization of sol-gel coatings applied on AA2024 substrate for corrosion protection, Corrosion Science, 111 (2016) 625–636.
Corrosion Protection of Internal Surface of Natural Gas Transmission Line By Metallic Coating
Authors: Tylczak Joseph H , Rodriguez Alvaro , Ziomek-Moroz Margaret
Published: February 2020

Natural gas transmission pipelines are a known to leak and thus release methane which is a greenhouse gas (GHG). There are several mechanisms for these emissions, including venting of lines, mechanical damage, and corrosion failure. With the projected pipeline life being described as “virtually forever”, slow corrosive attack can be an issue. The corrosive failure can be by either the exterior or interior attack. While there are practices in place to protect the exterior of the pipelines, including organic coatings and impressed cathodic protection, these techniques are not practical for the pipe’s interior. While dry natural gas is considered non-corrosive, the maintenance/inspect process of pigging of pipelines typicality results in black corrosion deposits being removed. These corrosion deposits are most likely a result of inadvertent water reacting with residual carbon dioxide (CO2) forming carbonic acid and attacking the pipeline, particularly wherever this water pools.

This research examined the use of sacrificial coatings on the interior of natural gas pipelines to protect the pipeline from corrosion. These tests simulated the case where trapped water is in the bottom of the pipeline. A typical natural gas pipeline can have 100 bar of pressure. The gas stream can have 3 to 4 vol % CO2. This can result in a CO2 partial pressure of 3 to 4 bars. NACE SP0106 says that CO2 at a partial pressure of greater than 2.1 bar in the presence of water is usually corrosive. Compression of the gas, which occurs every 40 to 100 miles, heats the gas which will accelerate the corrosion rate. The work examined the corrosion of an API 5L grade X65 steel in a test, 3 ½ wt. pct. NaCl solution with a 3.1 bar pressure of CO2 at 40 °C. Results of the corrosion rate of the bare steel were compared with that of several sacrificial metals, including Al and Zn. The corrosion rate of the steel coupled to sacrificial metals was measure for both parts of the couple.
Investigation of Corrosion Resistance for Annealed and Hardened Stainless Steels
Authors: Repukaiti Reyixiati , Fast Cody , Murkute Pratik , Tucker Julie , Isgor Burkan
Published: February 2020

Stainless steels are desirable for their good corrosion resistance and mechanical properties and are widely used in seawater exposure conditions that require high hardness. Heat treatment procedures to increase the hardness of stainless steel affect microstructural, compositional and surface properties of these materials, hence affect their corrosion resistance. To investigate this relationship a series of corrosion resistance and mechanical tests in room temperature and ambient pressure has been conducted for stainless steels (duplex 2101, duplex 2205, 17-4, 17-7, 15-5, 316, AL-6XN, Inconel600, ATI800, ATI347, 420) that are exposed to simulated seawater conditions to evaluate them in annealed and hardened conditions.

Preliminary salt solution spray tests have indicated that duplex stainless steel 2205, stainless steel 17-7, and stainless steel 15-5 have better corrosion resistance than other alloys in annealed condition. A series of electrochemical impedance and cyclic potentiodynamic polarization measurements were conduced for duplex stainless steel 2205, stainless steel 17-7, and stainless steel 15-5 in order to evaluate their corrosion resistance both in annealed and hardened conditions. Mechanical tests include micro hardness tests on annealed and hardened alloys, and charpy impact tests on hardened alloys. It was shown that the final selection of materials was primarily controlled by their corrosion resistance, as the mechanical properties of the alloys show only slight variation. The mechanisms that lead to changes in corrosion resistance due to heat treatment processes are discussed.
Microstrained Ptni/C Nanostructures As Highly Active Electrocatalysts for Electrooxidation and Electroreduction Reactions
Authors: Chattot Raphaël , Asset Tristan , Bordet Pierre , Drnec Jakub , Dubau Laetitia , Maillard Frederic
Published: February 2020

The electrical performance of a Proton Exchange Membrane Fuel Cell (PEMFC) is limited by the sluggish oxygen reduction reaction (ORR) kinetics. Thereby, the high platinum content needed at the cathodic catalytic layer to compensate these poor kinetics creates a major cost barrier for massive commercialization of PEMFC systems. Due to the strain and ligand effects, alloyed PtM/C or M-rich core@Pt-rich shell catalysts (where M is an early or late transition metal) have demonstrated tremendous ORR catalytic improvements compared to pure Pt/C. In this study, we synthetized and characterized nanometre-sized PtNi/C electrocatalysts with low Ni content (~15 at. %) but different nanostructures and different grain boundary densities: solid, hollow or “sea sponge” PtNi/C nanoalloys, Ni@Pt/C core@shell nanoparticles and solid Pt/C nanoparticles. These nanostructures were characterized by transmission and scanning-transmission electron microscopy, X-ray energy dispersive spectroscopy, Synchrotron wide-angle X-ray scattering, atomic absorption spectroscopy and electrochemical techniques. Their electrocatalytic activities for the ORR were determined, and structure-activity relationships established. The results showed that (i) the compression of the Pt lattice by 15 at. % Ni provides mild ORR activity enhancement compared to pure Pt/C, (ii) polycrystalline porous hollow nanoparticle feature dramatically enhanced ORR catalytic activity due to their highly defective nanostructure, (iii) the enhancement in ORR catalytic activity can be endorsed to the presence of grain boundaries as show two independent parameters: the microstrain determined from WAXS, and the average COads electrooxidation potential determined from COads stripping measurements. More results on methanol and ethanol electrooxidation suggest that structural defects produce a wide range of catalytic sites, resulting in versatile enhanced electrocatalytic performance.

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Biogas Upgrading in a 50 Kilowatt Solid Oxide Cells Based Demonstration Plant - Design and Operational Experiences Including Strategies to Counteract Degradation
Authors: Hansen John Bøgild
Published: February 2020

There are considerable incentives to use intermittent electricity generation for production of stporable energy carriers. Upgrading biogas to pipeline quality gas by methanation of the CO2 content in the biogas with hydrogen from electrolysis is one option.

Solid Oxide electrolysis (SOEC) offer strong synergy with the methanation plant, as the steam produced by the exothermal methanation reaction can be used directly as feedstock for the SOEC thus eliminating water evaporation by electricity.

A pilot plant to demonstrate the concept has been constructed and was operational mid 2016. The design capacity is 10 Nm3/h of upgraded biogas. This capacity requires approx. 50 kW SOEC, which is provided by two Fuel Cores, each consisting of 4 SOEC stacks. Haldor Topsøe A/S has also designed the biogas cleaning unit and the methantion plant which is located at the Agricultural Research Centre of Aarhus University at Foulum, Jutland.

 The paper will outline the design of the pilot as well as full scale plants including exergy analyses. Experimental data from the SOEC unit(s) as well as the biogas cleanup and methanation pilot will be presented.

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(Invited) Artificial Photosynthesis Using All-Solid-State Photocatalysts-Photocatalytic Conversion of CO2 By H2o As an Electron Donor-
Authors: Teramura Kentaro
Published: February 2020

Many research groups have already made significant progress in the field of water splitting to produce pure H2 and O2; in contrast, studies on the photocatalytic conversion of CO2 using H2O as a reductant are very few. This is because in such systems, overall water splitting occurs together with the reduction of CO2, resulting in H2 being the main product. Thus, it is very important to control the reduction of protons in the presence of both CO2 and H2O in order to achieve the reduction of CO2 by H2O. In this study, we found that Ag/ZnGa2O4/Ga2O3 exhibits a higher conversion of CO2 as compared to several photocatalysts reported previously. CO was evolved as the main product during the photocatalytic conversion of CO2 over Ag/ZnGa2O4/Ga2O3 under UV irradiation. H2 was simultaneously generated as the reduction product similar to CO, although the amount of H2 evolved was tiny as compared to that of CO. Expectedly, the evolution of O2 was observed together with those of CO and H2.
Atomic Layer Deposition of an Ultrathin Al2O3 Layer on TiO2-X Nanorods for Enhanced CO2 Photoreduction with Water
Authors: Zhao Huilei , Li Ying
Published: February 2020

Anatase TiO2 nanorods (ANR) with active facet {100} as the dominating facet were synthesized and oxygen deficient TiO2-X nanorods (ReANR) was prepared by reducing TiO2 using NaBH4. A thin layer of Al2O3 was coated on the surface of ReANR by atomic layer deposition (ALD), and the thickness of Al2O3 was tailored by varying the cycle number (1, 2, 5, 10, 50, 100, or 200) of ALD operation. The growth rate of Al2O3 was 0.25 Å per cycle as evidenced by high-resolution transmission electron microscopy, and the amorphous structure of Al2O3 was determined based on X-ray diffraction results. ANR, ReANR and Al2O3 coated ReANR were tested for CO2 photoreduction with water, with CO and CH4 as the major and minor products, respectively. Compared with ANR, ReANR had more than 50% higher CO production and more than ten times higher CH4 production due to the oxygen vacancies that possibly promoted CO2 adsorption and activation. With less than 5 cycles of ALD, Al2O3 coated ReANR had enhanced overall production of CO and CH4 than uncoated ReANR, with 2 cycles being the optimum, about 40% higher overall production than ReANR. Whereas, when more than 5 cycles were applied, both CO and CH4 production decreased with increasing number of ALD cycles. Photoluminescence (PL) analysis showed the both 2 cycles and 200 cycles of Al2O3 ALD coating layer on the ReANR were able to reduce the charge carrier recombination rate, likely because of the passivation of surface states. However, a relatively thick layer of Al2O3 may act as an insulation layer to prohibit electron migration to the catalyst surface. This work gives valuable insights on the application of ALD coating on photocatalysts to promote CO2 photoreduction to fuels.
Electrochemical Reduction of CO2 Using Cu-Au Nanoparticles: Effects of Size and Composition
Authors: Andrews Evan Michael , Flake John , Fang Yuxin
Published: February 2020

The electrochemical reduction of CO2 to light hydrocarbons allows renewable energy storage without increasing net atmospheric CO2. Alloys and nanoscale catalysts have emerged as potential electrocatalysts with high efficiencies and selectivities to valuable products. Here, we describe CuAu alloy nanoclusters with diameters of 2 nm and 5 nm for use as CO2 electroreduction catalysts. The Cu:Au ratio was controlled to yield nanoparticles with a range of alloy compositions ranging from Cu25Au75 to Cu72Au28. The yields and onset potentials were measured and compared to Cu, Au and CuAu bulk foils, where the nanoparticles showed a 50 fold increase in CO yield compared to Au foil, and greater than a 100 mV anodic shift in CO2 reduction onset potentials. As seen in Figure 1, the alloys showed greater improvements in yield as Au content increased. These improvements are attributed to low coordination active sites and to the bimetallic nature of these active sites.

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Carbon Dioxide (CO2) Electrocatalytic Recycling on Electrodeposited Nanostructured Copper-Gold Electrodes
Authors: Gandionco Karl Adrian , Sua-an Desiree Mae , del Rosario Julie Anne Dalmacio , Ocon Joey Duran
Published: February 2020

The electrocatalytic reduction of carbon dioxide (CO2) into hydrocarbons is considered as one of the promising solutions to the pressing problems related to energy and climate change as it can reduce atmospheric CO2 concentration and produce carbon-neutral energy. In this work, copper and gold on cabon fiber paper (Cu-Au/CFP) were studied as electrocatalysts for CO2 reduction. The electrocatalysts were synthesized via co-electrodeposition of metal precursors by applying a constant potential on an electrolyte solution containing cupric sulphate pentahydrate, gold (III) chloride trihydrate, and sulfuric acid. The concentration of the gold metal precursor in the electrolyte solution was varied from 5 to 50 mM whereas that of the copper metal precursor was kept constant at 0.40 M. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the morphology and crystallinity of the as-prepared electrocatalysts, respectively. It was determined through SEM that the as-prepared electrocatalysts are made of spherical and porous nanostructures. Fern-like structures were also observed to form when the concentration of the gold metal precursor in the electrolyte solution was increased. XRD analysis showed that Cu (III) dominated all other crystal structures in copper and gold electrocatalysts. The faradaic efficiencies of the electrochemical reduction of CO2 for alcohol and formate of the as-prepared electrocatalysts were found to be considerably higher as compared to that of copper electrode. The insights that are obtained through this study can be a guide for the synthesis of a better catalyst for CO2 electrocatalytic reduction.

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Understand the Hydrogen Electrode Reaction for Proton Conducting SOFC Via Controlled Poisoning Experiments Using Hydrogen Sulfide and Carbon Dioxide
Authors: Sun Shichen , Cheng Zhe
Published: February 2020

The hydrogen electrode reaction for conventional solid oxide fuel cells (SOFC) has been widely studied and well understood. In comparison, electrochemical behaviors for hydrogen electrode reaction of proton conducting SOFC are often distinctly different and there are still many unknowns about the fundamental kinetics and mechanism for such reaction. For example, it is well known that the hydrogen electrodes for conventional oxide ion SOFC, which consist of oxygen ion conducting oxides and Ni, are susceptible to poisoning by even sub-ppm level hydrogen sulfide (H2S). On the other hand, literature suggests that the hydrogen electrodes for proton conducting SOFC, which contains proton conducting oxides and Ni, show much better resistance against H2S. By understanding the origin of differences like this, new insights of the fundamental reaction mechanism for the hydrogen electrode of proton conducting SOFC can be obtained. In this study, electrochemical tests based on the concept of “controlled poisoning”, which is to selectively poison specific parts of the hydrogen electrode using low concentration of either H2S as a “Ni poison” or CO2 as a “proton conducting oxide poison”, are carried out to understand the fundamentals about the hydrogen electrode reaction for proton-conducting SOFCs. In particular, anode-supported cell with the configuration of Ni-BaZe0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb)/BZCYYb/LSCF and anode symmetrical cell with the configuration of Ni-BZCYYb/BZCYYb/BZCYYb were subject to ppm-level H2S and low percentage level CO2, and the electrochemical responses for both types of cells are characterized. Preliminary results show that, contrary to the Ni-based hydrogen electrode for conventional SOFC, the Ni-BZCYYb hydrogen electrode for proton conducting SOFC shows much better resistance against “sulfur poisoning” while gets poisoned by CO2 at low percentage level. Results for experiments aimed at understanding such differences will be presented and the implications on what the electrocatalytic roles of proton conducting oxides play in the hydrogen electrode reaction for proton conducting SOFC will be discussed.