bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon Anode Confined in Carbon Nano-Spaces for Efficient Lithium Storage
Authors: Jung Hyunyoung
Published: February 2020

Commercial Li-ion batteries employ graphite and other carbonaceous materials as anodes, which has excellent stability and low cost, but has a theoretical capacity limit at 372 mAh/g by forming a fully intercalated LiC6 compound. For anode materials, silicon is also known to have the highest theoretical specific capacity (4200 mAh/g), and is considered to be the active materials for the next generation lithium ion batteries. However it has the large volume change (>400%) during lithiation and delithiation causes pulverization, resulting in capacity loss in a high number of cycles. Here, this study reports the use of engineering nanocarbon film with confined silicon nanoparticles as an anode material for lithium-ion batteries. The unique “concave” graphitic nanostructure, prepared in porous templates with morphology of interconnected arrays, makes nanocarbon electrodes a good lithium-ion intercalation medium and, more importantly, robust nanocontainers to effectively confine high-capacity silicon nanoparticles for lithium-ion storage. Our unique anode, which is based the concave graphitic film and silicon particles confined in its nanospace, have three notable features for the use as the effective electrode material in a lithium-ion battery. First, Li ion diffusion into the interior of the nanocarbons through the opened structures can shorten the diffusion length of the redox couple and provide rapid charge transport. Second, the exposed silicon active materials in the direction of Li ion diffusion increase the accessibility of the electrode interior to the electrolyte, which ensures a high charge/discharge capacity. Finally, the nanoconfined silicon system inside the carbon nanospace improves the cycle life by preventing volume expansion during electrochemical Li insertion/extraction. As a result, high performance Li storage with a mass-specific capacity of 2500 mAh/g was obtained at 0.5A/g. The discharge capacity was retained constantly during 200 cycles with coulombic efficiency of above 98%. These results suggest that the novel structure can lead to high storage capacities and rate capability as anode material in future high performance Li-ion batteries.
Small Functional Molecules As Slurry Additives for Si-Alloy Coatings with CMC/SBR Binder
Authors: Wei Congxiao , Obrovac M. N.
Published: February 2020

Si-alloy based anodes are attractive for use in Li-ion batteries because of their high volumetric capacity. Polyacrylic acid (PAA) [1] binder is often used in such anodes, which contains carboxyl groups that bind to alloy surfaces, maintaining electrode integrity and forming an artificial SEI layer [2]. Aromatic binders like PI can decompose during lithiation, forming a conductive carbon network [3]. However, these binders have disadvantageous for their practical use, including superhydrophilicity, in the case of PAA; and high irreversible capacity and the cost and use of NMP solvent, in the case of PI. Sodium carboxymethyl cellulose/styrene-butadiene rubber (CMC/SBR) is currently the binder system of choice for Li-ion cell makers. Enabling the use of CMC/SBR binders with alloys could enable wider implementation of alloy electrodes.

In this work, several small molecule compounds containing carboxyl groups were evaluated as slurry additives. It was found that some slurry additives could significantly improve alloy cycle life in CMC/SBR coatings. Figure 1 shows the capacity retention versus cycle number for each slurry additive. Tremendous variations in capacity retention are observed for different additives. In particular, the addition of 5% sodium mellitate and sodium citrate resulted in a large increase in cycling performance of the CMC/SBR coating beyond even that of a coating with PAA binder. This work shows that the cycle life of alloy coatings using CMC/SBR binder can be improved by the use of small molecule slurry additives. This could help enable the use of alloy based electrodes in Li-ion batteries using practical binder systems.

Reference
s
:

[1] Magasinski, Alexandre, et al. "Toward efficient binders for Li-ion battery Si-based anodes: polyacrylic acid." ACS applied materials & interfaces 2.11 (2010): 3004-3010.

[2] Chen, Hao, et al. "Exploring chemical, mechanical, and electrical functionalities of binders for advanced energy-storage devices." Chemical reviews 118.18 (2018): 8936-8982.

[3] Wilkes, B. N., et al. "The electrochemical behavior of polyimide binders in Li and Na cells." Journal of The Electrochemical Society 163.3 (2016): A364-A372.

Figure 1
Synthesis of Silicon-Germanium Compounds Anode Material By Potentiostatic Electrolysis Method in Molten Salt for Lithium-Ion Battery
Authors: Yan Yongde , Song Yali
Published: February 2020

The fourth host materials (carbon, silicon, germanium, etc.) have high theoretical capacity and are usually used as anode materials for lithium ion batteries. Nanowires are considered to be excellent structures for high performance anode materials due to their good mechanical properties, which are conducive to electron transport and ion diffusion, as well as to improve structural deformation. Molten salt has the advantages of simple operation, high product activity and high yield. In this paper, the electrochemical reduction mechanism of silicon and germanium alloy was studied by means of cyclic voltammetry and potentiostatic electrolysis, and a series of germanium and silicon based materials were prepared by molten salt electrolysis. The method of preparing composite material by molten salt electrolysis is also provided. Si-Ge heterostructure nanowires were synthesized in NaCl-CaCl2 eutectic molten salt by potentiostatic electrolysis. The nanowires have high specific capacity, high volume capacity, good mechanical properties and stable diffusion path. It is beneficial to improve the electrochemical performance of lithium ion battery (recirculation and specific capacity).

Figure 1
Investigation on Formation Process of Lithium-Ion Batteries
Authors: Kim Youngmin , Jeong Kyeong-Min
Published: February 2020

To increase the energy density and the power density of lithium ion battery cell, it is important to design the capacity of each electrode accurately. Ideal lithium-ion battery should be formed SEI film through the first charge/discharge, after then should maintains 100% coulombic efficiency1. In reality, such a perfect formation cannot be achieved within one cycle, and reduction in cell capacity occurs with repeating charge/discharge cycle. This makes hard to measure the irreversible capacity accurately, so it is important to finish formation process in one cycle for cell design and process design.

In this work, we confirmed that the 0.1C charge as the formation protocol does not complete the formation with electrochemical impedance spectroscopy using graphite half-cell. In addition, we investigated how the cell capacity and the coulombic efficiency changes as the cell is cycled by varying the current applied in the CC process or time taken for the CV process during CC-CV charging protocol by graphite half-cell and Li [Ni0.6Co0.2Mn0.2] O2 / graphite cells.

We investigated whether we could accelerate the formation of lithium-ion batteries with variation of charging protocol. According to the experimental results, the film resistance of the graphite electrode decreased as the cell formation completed. When the film resistance of graphite decreases, equilibrium potential increases so the utilization of graphite active material would be increased in the subsequent cycles. This is followed by the abnormal behavior of capacity and coulombic efficiency. In charging/discharging graphite half-cell, we confirmed that higher portion time taken of charging with CV in first charge leads to earlier completion of formation. Change in film resistance, capacity, and coulombic efficiency will be discussed.

References

Principles and Applications of Lithium Secondary Batteries, Jung Ki Park.
Characterization of Aged Li-Ion Battery Electrodes for Direct Recycling Process Design
Authors: Fink Kae , Santhanagopalan Shriram
Published: February 2020

Developing a recycling protocol for lithium-ion batteries (LIBs) at their end of life is crucial to both supply chain stability and waste mitigation. Novel nondestructive recycling methods are under investigation, but lack the process engineering specifications required for full-scale operation. Specifically, the ability of end-of-life LIB components (i.e., recycling feedstock) to withstand the mechanical stresses inherent in industrial reprocessing techniques has not been established. To this end, we have mechanically characterized the electrodes of both fresh cells and “cycled-aged” (C-A) cells (cells that have been cycled and subsequently calendar-aged, and thus reflect a representative recycling input). We report the components’ performance under uniaxial tensile stress and compressive loads, and determine the effects of tensile strain rate and electrode coating on mechanical response. Further, we explore how these measured mechanical properties affect design parameters for a roll-to-roll (R2R) direct recycling process. Cycle-aging is found to significantly reduce the tensile strength of coated electrodes across all strain rates, and electrodes are found to have significantly lower elastic moduli than their respective current collectors. Positive strain rate dependence is observed for bare current collectors but not for coated electrodes, implying that the coating of active material permanently alters the current collector matrix. Compressive failure is not observed for any of the samples; however, C-A cathodes reach elastic deformation at a lower strain than do fresh cathodes. In the context of direct recycling, these findings suggest that roll tension may need to be reduced by 13-65% for C-A components relative to fresh components to avoid irreversible damage. Additionally, C-A cathodes are expected to permanently deform at a lower calendering force than fresh cathodes. Finally, we have investigated each component’s contribution to overall cell capacity loss, and have probed the degradation mechanisms of cathodes to inform recycling method development. Electrochemical analysis suggests that phase shift (layered to spinel phase) and buildup of electrolyte residues at both the primary particle and in the inter-particle pore space may significantly contribute to cathode degradation. Washing C-A cathodes with aprotic solvents is found to improve half-cell cycling performance, likely due to the removal of electrolyte residues, but does not reverse structural degradation. These electrochemical results suggest the importance of a washing step prior to chemical relithiation in direct recycling methods. Thus the present work, which combines mechanical and electrochemical analyses of cycle-aged LIB components, informs the process design of industrial-scale nondestructive LIB recycling.
Computational Design of Electrode-Electrolyte Interfaces for Solid-State Lithium Ion Batteries
Authors: Wang Chuhong , Mueller Tim
Published: February 2020

All-solid-state lithium-ion batteries have attracted significant interest for their enhanced safety compared with conventional batteries employing an organic liquid electrolyte. However interfacial reactions between the electrodes and the electrolyte can increase the impedance of charge carrier transfer, degrading battery performance. In this work, we present a systematic high-throughput screening method to identify coatings for interfaces based on thermodynamic phase equilibria to maintain long-term interface stability during battery operation. Using Monte Carlo simulated ab initio phase diagrams, our approach can incorporate metastable phases in the coating materials screening and identify potential multi-layer coatings. We identified single- and double-layer coatings for 56 combinations of common electrode and electrolyte materials from existing databases of inorganic materials. Top protective coatings were further evaluated on their electrical resistance, ionic conductivity and electrochemical stability. Our work provides a general approach to mitigating interfacial reactions and optimizing battery performance by rational coating design.
Relithiation of Cathode Materials for the Recycling of Lithium-Ion Batteries
Authors: Montoya Anthony , Vaughey John T.
Published: February 2020

As the production of lithium-ion batteries (LIBs) increases, the need for the raw materials grows at a rate that may either exceed the annual supply available or become cost prohibitive under present formulations. Recycling components from depleted LIB systems represents an alternative feedstock to meet predicted the demand for raw materials and provides a market for used batteries. A large component of the cost of LIBs come from the metals used in the cathode and the fluoride salts used in the electrochemical cells and being able to reuse these materials is of critical importance. End of life LiNi0.33Mn0.33Co0.33O2 (NMC111) cathodes are typically 15-20% lower in lithium content than fresh cathode. The goal is to return the cathode back to the starting composition through direct chemical relithiation without causing change to the structure. This direct recycling process retains most of the energy already invested in creating the cathode creation by maintaining as much of the structure as possible. Baseline NMC cathodes were chemically delithiated to known concentrations (15-25% removal) by treatment with (NH4)2S2O8. A chemical approach to cathode relithiation by heating delithiated NMC with different lithium sources (Li2CO3, LiOH, Li2O) taking into account thermal stability windows and the emergence of Li/Ni antisite mixing will be described in this presentation. Samples were characterized by powder XRD, scanning electron microscopy, GDOES, ICP and electrochemical evaluation.

Figure 1
(Invited) Multiscale Analysis of Battery Materials Using X-Ray Microscopy
Authors: Nelson George J.
Published: February 2020

Battery electrodes are inherently multiscale, functional material systems that provide sites for chemical reactions and pathways for charge and reactant transport. A greater understanding of the interaction between transport phenomena, electrochemistry, and electrode structures is critical to advance battery performance and reliability. Direct microstructural imaging methods provide a unique capability for the multiscale observation of electrode structures and the material changes that occur during battery operation. The microstructural image data produced by these methods also facilitates physics-based simulation informed by real device structures. Applications of X-ray microscopy to battery electrodes at multiple scales are presented. X-ray nanotomography (XNT) and microtomography (µCT) of battery electrode materials are presented for high capacity metallic anode materials and transition metal oxide cathode materials. First, X-ray imaging is presented as a means of assessing the impact of processing methods on electrode structure at nano- and micro-scales. Ex situ and in operando spectroscopic imaging using µCT and nano-scale X-ray absorption near edge structure (XANES) are then presented as a means of assessing multiscale chemical and structural changes in electrodes during cycling. The data obtained through these imaging efforts facilitates modeling of real electrode structures. Modeling efforts informed by the microstructural data obtained are discussed with a focus on Li-ion cathode materials. Observations from modeling are complemented by microstructural analysis that permits description of cathode performance in terms of dimensionless parameters.
Morphology and Phase Changes in Fe Anodes for Rechargeable Alkaline Batteries
Authors: Lee Dong-Chan , Yushin Gleb
Published: February 2020

Rechargeable alkaline batteries may become promising non-flammable alternatives to Li-ion batteries for the applications where achieving the highest energy density is less critical than safety, environmental friendliness and low cost of energy storage systems. A renewed interest on Ni-Fe aqueous batteries awakes due to the aforementioned advantages as well as long life and robustness against harsh conditions. The challenges for improved Ni-Fe batteries, however, remain limiting their utilization for large-scale energy storage systems: electrolyte decomposition, high self-discharge and poor cell efficiency. Such drawbacks can be overcome by sound understanding on the cell reactions happening at the electrodes.

By conducting systematic studies on Fe anodes using cyclic voltammetry and a broad range of characterization tools, four distinct stages of Fe anode evolution were revealed: development, retention, fading and failure, where each stage is associated with very specific changes in the morphology and phase of Fe anodes. The particle fragmentation with the consequent gain in the surface area resulted in the increase in the Fe anode capacity during the initial cycles of deep charge/discharge. Most importantly, it was discovered that the irreversible formation of monocrystalline maghemites (γ-Fe2O3) with low reactivity is responsible for the eventual Fe anode capacity fading. We confirmed that the microstructure change takes over during early charge-discharge cycles of Fe anodes while their phase change is dominant at later stage which is the key for the rationale explaining the failure mechanism of Fe anodes in Ni-Fe batteries. Ultimately, our study correlates the changes in the electrochemical behavior of micro-scale Fe upon deep cycling in alkaline conditions with the changes in its morphology and phase.

* DOI: 10.1021/acsenergylett.8b00063
(Invited) Electrochemistry at Georgia Tech: Early Days of the Georgia Local Section
Authors: Kohl Paul A
Published: February 2020

The Georgia Local Section was first proposed in 1990 by Jack Winnick, Paul Kohl and Larry Bottomley to be the “Southeastern Section” in hopes that It would include ECS members in Alabama, Tennessee, South Carolina and possibly Florida. ECS eventually chartered Section in 1991 as the Georgia Section with participation from Alabama, South Carolina and Tennessee. In this talk, some of the early electrochemical projects and events of the Georgia Section will be presented.
(Invited) 2D MXenes As Building Blocks for Assembly of High-Performance Electrodes for Electrochemical Energy Storage
Authors: Beidaghi Majid
Published: February 2020

Two-dimensional (2D) transition metal carbides/nitrides (MXenes) have shown promise for a range of applications due to their unique physical and chemical properties. The high electrical conductivity, 2D and layered structure, and rich surface chemistry of MXenes have sparked great interest in their properties as electrode materials for energy storage devices. MXenes are particularly of high interest because they can store charge in the bulk of the electrode through ultrafast intercalation of ions and fast and reversible redox reactions. To date, about 30 different MXenes with a general formula of Mn+1XnTx (M is a transition metal, X is carbon and/or nitrogen, n=1,2, and 3, and Tx represents different functional groups present at their surface) are synthesized by selective etching of the A layer atoms (i.e. Al) from MAX phases (e. g. Ti2AlC), a large group of layered ternary carbides and nitrides.1 However, similar to other 2D materials, the applications of MXenes in batteries and supercapacitors is dependent on their assembly into electrode structures with high electrical and ionic conductivities. The main focus of this talk is our group’s recent research on the assembly of MXene flakes into electrode structures with high energy and power densities. We have found that the electrochemical properties of MXene electrodes are highly dependent on the size of MXene flakes used in their fabrications.2,3 Controlling the flake size in the electrode structures leads to significant improvements in their specific capacitance and rate capability. Furthermore, our recent studies on the assembly of multilayer MXenes films and particles using electrostatic assembly methods will be discussed. The electrodes fabricated by these methods show superior chemical and electrochemical stabilities as well as energy storage capability.4 Finally, our work on 3D assembly of MXenes through a versatile 3D printing process will be presented.

References

(1) Anasori, B.; Lukatskaya, M. R.; Gogotsi, Y. 2D Metal Carbides and Nitrides (MXenes) for Energy Storage. Nat. Rev. Mater.
2017, 2 (2), 16098. https://doi.org/10.1038/natrevmats.2016.98.

(2) Kayali, E.; VahidMohammadi, A.; Orangi, J.; Beidaghi, M. Controlling the Dimensions of 2D MXenes for Ultrahigh-Rate Pseudocapacitive Energy Storage. ACS Appl. Mater. Interfaces
2018, 10 (31), 25949–25954. https://doi.org/10.1021/acsami.8b07397.

(3) VahidMohammadi, A.; Moncada, J.; Chen, H.; Kayali, E.; Orangi, J.; A. Carrero, C.; Beidaghi, M. Thick and Freestanding MXene/PANI Pseudocapacitive Electrodes with Ultrahigh Specific Capacitance. J. Mater. Chem. A
2018, 6 (44), 22123–22133. https://doi.org/10.1039/C8TA05807E.

(4) VahidMohammadi, A.; Mojtabavi, M.; Caffrey, N. M.; Wanunu, M.; Beidaghi, M. Assembling 2D MXenes into Highly Stable Pseudocapacitive Electrodes with High Power and Energy Densities. Adv. Mater.
2019, 31 (8), 1806931. https://doi.org/10.1002/adma.201806931.
(Invited) Extracellular Matrix-Based Neural Interfaces
Authors: Shen Wen , Allen Mark
Published: February 2020

Neural interfaces to reveal neural activities at high temporal and spatial resolutions become critical for neuroscience research, emerging clinical applications and brain computer interfaces (BCI). However, the chronic performances of conventional neural interfaces degrade over time due to their incapability to address the biological, chemical and mechanical properties of neural tissues. Extracellular matrix (ECM) materials offers several intrinsic properties, such as high mechanical flexibility and biocompatibility, making them uniquely suitable for interfacing with neural tissues. In this talk, I will present our recent work on ECM-based neural interfaces, highlighting the microfabrication of ECM-based neural electrodes, the mechanical, electrochemical and biological characteristics of the ECM-based neural interfaces, and finally discuss several application examples.
Computational Insights into the Lithium Intercalation Dynamics in Manganese Oxide Cathodes
Authors: Kempaiah Ravindra , Narayanan Badri , Sankaranarayanan Subramanian K. R. S. , Subramanian Arunkumar
Published: February 2020

Research solutions that improve the performance of Li-ion batteries are essential to meet the future needs of the electric grid and transportation industries. Increasing costs associated with sourcing Cobalt has spurred demand for new cathode materials that are inexpensive and environmentally-friendly. Manganese oxides (MnO2) are an important class of electrochemically active transition metal oxides, which have been extensively studied as a potential candidate for replacing cobalt.[1] Alpha-MnO2 is an MnO2 polymorph, which contains structurally stable and porous 2x2 tunnels with tunnel widths in the range of ~5Â. These tunnels, which are formed by edge and corner sharing MnO6 octahedra, provide low-energy sites for ionic insertion and offer suitable diffusion pathways for intercalating ions.[2] Cationic species such as Na+, K+, and Li2O reduce the lithiation-induced structural distortion in these tunnels and offer a pathway for stabilizing the tunnels during electrochemical cycling.[3,4] This poster presents results from ab-initio Density Functional Theory (DFT) based computational studies to reveal new insights into the impact of cationic stabilization on the intercalation dynamics of these materials, which are otherwise difficult to obtain directly from spectroscopic or electron microscopy techniques. Using alpha-MnO2 as a model material, we present the correlation between the concentration of cationic species and its resulting impact on lithium diffusion in the following aspects: (i) energetic barriers for Li diffusion, and (ii) structural distortions induced within the tunnels.

References:

Thackeray, Michael M., et al. Journal of Materials Chemistry23 (2005): 2257-2267.

Yuan, Yifei, et al. Nano letters5 (2015): 2998-3007.

Tompsett, David A., et al. Chemistry of Materials12 (2013): 2515-2526.

Ling, Chen, et al. Chemistry of Materials20 (2012): 3943-3951.
Investigating Hybrid Organic-Inorganic Tin Perovskites for Li-Ion Battery Applications: DFT Modeling Approach
Authors: Kim Jihoon , Allam Omar Adel , Jang Seung Soon
Published: February 2020

This study highlights the application of 3D hybrid organic-inorganic perovskites (HOIPs) for use in lithium-ion battery electrode applications. Demand for more efficient electrochemical storage materials is rising year by year in a wide range of practical applications. HIOPs have attracted intensive attention for many applications mainly due to the highly versatile nature of perovskites as well as their solution-processability at low temperatures. The use of perovskite in Li-ion batteries has only been recently examined as most studies so far have focused on the use of HOIPs for optoelectronic applications. Specifically, most recent studies have examined the use of lead based HOIPs, which possess a number of possible environmental concerns due to the toxicity of lead. Thus, in this study, we use DFT to investigate lithium intercalation in alternative tin based perovskites (ASnX3, where A = MA+, FA+, and Cs+ and X = Cl-, Br-, and I-). We characterize the performance of these perovskites for Li-ion applications by considering the intercalation voltage for lithium as well as the structural distortions incurred by the SnX6 octahedra.
Design of a Multi-Layer Hydrogel Nanocomposite for Real-Time Evaluation of Properties Relevant to Wound Management Applications
Authors: Linhart Abigail N. , Danhausen Dany M , Keleher Jason J.
Published: February 2020

Hydrogels have emerged in the biomedical field as alternatives to traditional wound dressings due to their well-defined structure and intrinsic properties such as swellability and biocompatibility. These supramolecular nanocomposites can be modified with various additives including metal ions, organic crosslinkers, antimicrobial agents, and conductive polymers to enhance these properties as well as promote responsive characteristics. This research focuses on the development of a nanocomposite to monitor the properties (oxygen diffusion and antimicrobial effectiveness) and lifetime (swellability) of a hydrogel in real-time. More specifically, this nanocomposite is a multi-layered system in which the first layer consists of a biomimetic, alginate hydrogel containing functionalized metal nanoparticles (MNPs). The MNPs role is two-fold: to provide structural rigidity with enhanced electron transport and serve as a solid support for the functionalization of antimicrobial agents at the wound surface. The top scaffold of the composite is the bulk conductive polymer matrix that serves as the signal-response layer (i.e. receives charge from the biomimetic layer). Initial results show, as a simulated wound secretes, ions diffuse through the biomimetic hydrogel into the bulk conductive layer increasing the electron density to enhance the conductivity via p-doping. The changes in voltage and current can be used to track the integrity of the matrix as well as properties such as oxygen diffusion and antimicrobial effectiveness. Furthermore, results indicate a strong correlation between hydrogel matrix porosity and electrical responsiveness of the resultant nanocomposite material.
Hierarchical Iron/Nickel-Based Sulfide Supported on Ni Foam As a Bifunctional Electrocatalyst for Efficient Overall Water Splitting
Authors: Lim Dongwook , Kim Namil , Kim Minsoo , Baeck Sung-Hyeon
Published: February 2020

Water splitting, consisting of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), has received great attention owing to the potential to provide future sustainable and renewing energy source. However, the kinetically sluggish process of OER at anode and HER at cathode requires highly active electrocatalysts to accelerate the both electrode reactions. Currently, nickel-based catalysts are widely regarded as an effective electrocatalyst for OER due to their low cost, high stability, good redox properties, and high electrocatalytic performance. Herein, iron/nickel-based sulfide supported on Ni foam were simply synthesized using two step hydrothermal method and was used as a bifunctional electrocatalyst for OER and HER. The iron/nickel-based sulfide only require the low overpotentials of as smaller as 281 and 222 mV for HER and OER, respectively, at current density of 50 mA cm−2 in 1 M KOH. Assembled as an electrolyzer for overall water splitting, this bifunctional catalyst also indicates excellent low onset potential of only 1.41 V and deliver a current density of 10 mA cm−2 at a very low cell voltage of 1.59 V. The outstanding electrochemical performance of iron/nickel-based sulfide on Ni foam is mainly attributed to the synergistic effect of the binary metal system, leading to increasing the electroconductivity, active surface area, and intrinsic catalytic activity. These iron/nickel-based sulfide materials can be widely applied to fabricating efficient energy conversion and storage.
Corrosion Behavior of Cocrfemnni High Entropy Alloy in Acidic Solutions
Authors: Aiso Takumi , Muto Izumi , Sugawara Yu
Published: February 2020

High entropy alloys (HEAs) are new concept in alloy design. HEAs contain five or more metallic elements in equimolar or near-equimolar ratios. Although HEAs are multi-component alloys, they form single-phase solid solutions. HEAs have outstanding properties that were not found in conventional alloys such as Fe-base alloys. CoCrFeMnNi alloy, one of the most remarkable HEA, is expected to exhibit high corrosion resistance. The mechanism of corrosion resistance of CoCrFeMnNi alloy could be applied to improve the corrosion resistance of conventional Fe-Cr-Ni stainless steels. Therefore, it is important to clarify the corrosion mechanism of CoCrFeMnNi alloy.

In this study, the equiatomic CoCrFeMnNi alloy was prepared as the specimens. CoCrFeMnNi alloy was made by arc melting. The samples were heated to 1523 K and hot-rolled to thickness of 2 mm. After solution treatment at 1473 K (2h, W.Q.), the surfaces of the specimens were successively polished with a diamond paste down to 1 µm.

Potentiodynamic anodic polarization curves were measured in deaerated 1 M H2SO4 at 298 K to elucidate the corrosion behavior of CoCrFeMnNi alloy. As a reference, polarization curves for pure Co, Cr, Fe, Mn, and Ni were measured. The surfaces of the specimen, with the exception of the electrode area (10mm×10 mm), were covered with epoxy resin and paraffin. The measurements were performed in a conventional three electrode cell. The reference electrode was Ag/AgCl (3.33 M KCl) and the counter electrode was a Pt plate.

The results of potentiodynamic anodic polarization curves are shown in Fig. 1. In the case of CoCrFeMnNi alloy, active state, passive, trans-passive, secondary passive, and O2 evolution regions appeared. Comparing with CoCrFeMnNi alloy and each pure metal, corrosion reactions of CoCrFeMnNi alloy were discussed.

Figure 1
(Invited) Saft Gen 6 Electrochemistry for GEO/LEO Application
Authors: Ma Chengsong , Borthomieu Yannick
Published: February 2020

Satellite battery industry is facing a serious material obsolete issue. The MCMB anode and NCA cathode active materials were no longer available. Saft developed a Generation 6 space cell –VL51ES which addressed material obsolescence in the space industry and provided high specific energy to meet the demands of today’s space missions.

The selected electrodes electrochemistry provides excellent storage and cycle life. VL51ES is an iteration of proven technology and a legacy of failure-free batteries with up to 18 years in space. Manufactured in both France and the US, the redundant manufacturing capability ensures effective product delivery to customers across the globe. Saft incorporated advanced technology and enhanced manufacturing processes. Compared with the previous generations of space cells, the Gen 6 space cell is more industrialized, efficient and cost effective. Change from tabbed design to tabless design significantly reduces cell impedance, it makes VL51ES capable for higher rate discharge and cold temperature charge than previous Saft space cells. It represents a 20% height reduction along with a 10% improvement in energy. This cell has excellent GEO mission life, 45 accelerated GEO seasons were demonstrated with only 6% total energy loss. VL51ES passed voltage reversal tests without safety event, it enables a by-pass less battery design to reduce cost and complexity at battery level and maintain the same reliability. The qualification of VL51ES covers a full range of space requirements including safety, electrical, mechanical, abuse, life test and reliability. A data package has been compiled for customers with records of all test results. The qualification data is incorporated into Saft’s Li ion model (SLIM) which help customers to predict battery life performance at different scenarios and help customer with proper battery sizing.
Electrophoretically Deposited Graphene-Based Coatings for Spacecraft Charging Mitigation
Authors: Wang Dan , Liu Danny X. , Hall Timothy D. , Inman Maria , Taylor E. J. , Skinn Brian , Snyder Stephen
Published: February 2020

Spacecraft charging has been recognized as an important consideration for spacecraft design, and occurs due to interaction between hazardous space plasmas and spacecraft surface. Spacecraft can experience charging throughout operation due to high flux of incident electrons (ex. during geomagnetic sub-storm). As a result, different materials/components may experience a range of potentials which may lead to plasma-induced arcs, damaging spacecraft components. Graphene are emerging two-dimensional (2D) carbon materials with excellent physical and chemical properties, such as high conductivity, high tensile strength, high transparency, and high carrier mobility. These excellent properties make graphene potentially useful for applications in energy storage, aerospace, coatings and polymer markets and thermal protection. Substrates constituted by graphene harness the thermal and mechanical properties to create novel coatings with superior performance, hence broadening the graphene application spectrum. Of particular interest is the potential capability of graphene-based materials to provide increased protection against spacecraft charging in the space plasma environments. The work function of graphene can be tuned by either metal doping or functionalization, thereby increasing the electron yields and enhancing the possibility of emission through negative electron affinity.

Within this context, Faraday Technology is working on developing an electrophoretic bath formulation and manipulate the pulsed electric field parameters to deposit graphene-based coatings onto test substrates, which may maintain integrity of spacecraft by autonomous electron emission in relevant environments. As shown in the Figure, uniform graphene-based coatings have been formed on an aluminum substrate. The coatings are characterized and evaluated by optical microscopy, scanning electron microscopy, and field-emission scanning electron microscopy. Faraday will also investigate the incorporation of metal particles into graphene film to tailor the emission properties, allowing for obtaining the low work function. The demonstrated technology not only addresses the desire to introduce novel manufacturing techniques for spacecraft charging mitigation, but also provides a scalable thin film and low-cost manufacturing process that has the potential of producing low reflective coatings.

Acknowledgements: The financial support of DOD Air Force Contract No.: FA9453-19-P-0573 is acknowledged.

Figure 1
In Situ Characterization of the Lithium Metal Interface
Authors: Lopez Jeffrey , Shao-Horn Yang
Published: February 2020

Lithium ion batteries have become the dominant form of energy storage used in consumer electronics and, recently, electric vehicles. However, high costs have prevented widespread deployment of lithium ion batteries for applications other than portable electronics, and the safety issues associated with liquid organic electrolytes remain to be addressed. In order to enable the greater utilization of electric vehicles, allow for grid scale energy storage, and meet the demands of new electronic applications, new materials for high energy density batteries must be developed. High capacity electrode materials like lithium metal have the potential to facilitate these technologies, but lithium metal electrodes are presently limited by significant side reactions, poor quality deposition, and the potential to form hazardous dendrites. Therefore, it is important to develop a clear understanding of the surface reactivity and growth behavior of the lithium metal at the interface with the electrolyte in order to enable stable long-term cycling.

The products that form as a result of electrolyte decomposition reactions at the electrode interface are known to be extremely important in determining the final cell performance. Specifically, fluorinated salts and solvent additives have been shown to enable stable cycling of Li metal anodes. This improvement is ascribed to the formation of LiF in the solid electrolyte interphase (SEI), yet the understanding of how LiF and other SEI compounds are formed and how they affect battery cycling is not complete. In this presentation, in situ spectroelectrochemical techniques including infrared spectroscopy (FTIR), differential electrochemical mass spectrometry (DEMS), and electrochemical quartz crystal microbalance (EQCM), are used to clearly identify components of the Li metal SEI. An understanding of SEI formation with respect to electrochemical potential and time will be discussed. With this understanding we provide new insights into the formation and chemical nature of SEI components that promote stable cycling of lithium metal electrodes.
A Study of Practical Obstacles in Primary and Rechargeable Alkaline Zinc-Air Batteries
Authors: Sun Wei , Zhang Mengyi , Bieker Peter , Winter Martin
Published: February 2020

As one of the proposed post lithium-ion battery technologies, metal-air batteries have received revived interest recently. Among the different types of metal-air batteries, rechargeable zinc-air battery (RZAB) is a promising electrochemical energy storage device with the advantages of high theoretical energy density of 1086 Wh kg-1, high abundance, low toxicity and intrinsic safety.1 However, current RZAB still suffer from poor energy efficiency and cycle life, owing mainly to the zinc-anodes, electrolytes, and air-cathodes. To improve the low energy efficiency, many efforts have been made to promote both of the sluggish oxygen reduction/evolution reactions in the air-cathodes by engineering bifunctional catalyst materials with high reactivity. Although significant progress has been made in developing suitable catalyst materials for the air-cathode, many technical challenges still remain in electrolyte to achieve the long cycle life while maintaining high performance.

Aqueous electrolytes, predominantly alkaline electrolytes, have been adopted by the RZAB system since its birth. Potassium hydrogen (KOH) is the most commonly used alkaline electrolyte because of its high ionic conductivity, high activity for both the zinc and air electrodes as well as good low temperature performance.2 Despite its desirable properties, the usage of KOH in RZAB raises several technical problems: i) zinc dendrite formation, shape change, surface passivation from complicated reaction between zinc and OH- as well as the dissolution and migration of Zn(OH)4
2-; ii) corrosion of the carbon-based air cathode in concentrated alkaline electrolyte; iii) formation of insoluble K2CO3 arising from the reaction of aerial CO2 with KOH; iv) reduced cell shelf due to the high corrosive ability of concentrated alkaline electrolyte to the stainless steel used in the experimental cell component.

In this work, specific attention is given to the obstacles caused by the alkaline electrolytes with the focus on the fundamental understanding of zinc-anode reaction mechanisms, carbonization of electrolyte as well as the precipitation of carbonates on the air cathode. Furthermore, the effects of the practical operating conditions on battery performance and durability are discussed, including the experimental cell configuration for RZAB as well as the contaminants commonly encountered in ambient air (e.g. carbon dioxide). The approaches to overcome the challenges are also presented and analyzed for facilitating further research and development of the electrolyte for RZAB.

Reference

Li, Y.; Dai, H., Recent advances in zinc-air batteries. Chemical Society reviews
2014,
43 (15), 5257-75.

R. Mainar, A.; Leonet, O.; Bengoechea, M.; Boyano, I.; de Meatza, I.; Kvasha, A.; Guerfi, A.; Alberto Blázquez, J., Alkaline aqueous electrolytes for secondary zinc-air batteries: an overview. International Journal of Energy Research
2016,
40 (8), 1032-1049.
(Battery Division Research Award) Advanced Energy Storage Systems for Enabling Electrification of Vehicles “Lithium Ion & Beyond”
Authors: Amine Khalil , Lu Jun , Xu Gui-Liang , Chen Zonghai , Curtiss Larry A
Published: February 2020

To meet the high-energy requirement that can enable the 40-miles electric drive Plug in Hybrid Electric Vehicle (P-HEVs), long range electric vehicle (EV) and smart grid, it is necessary to develop very high energy and high power cathodes and anodes that when combined in a battery system must offer 5,000 charge-depleting cycles, 15years calendar life as well as excellent abuse tolerance. These challenging requirements make it difficult for conventional battery systems to be adopted in P-HEVs and EVs. In this talk, we will present a next generation lithium ion battery that include Ni rich full gradient cathode, a high voltage and nonflammable electrolyte and Silicon-graphene composite anode including a novel pre-lithiation technology to overcome the irreversible loss of this anode in the first cycle. We will then show how Se doping of Sulfur (S) can overcome the conductivity issue of S and eliminate the dissolution of poly-sulfide using an advanced electrolyte system. We will also show that by incorporating Li2S in graphene cages, we increase the electrode loading significantly to over 10mg.cm-2 and eliminate the issue of cathode swelling and the use of Lithium metal that impact performance.
Highly Reduced Aqueous Polyoxometalate Solutions for on-Demand Hydrogen Generation and Energy Storage in Redox Flow Batteries
Authors: Symes Mark , Chen Jia Jia , Cronin Leroy
Published: February 2020

As our reliance on renewable energy sources grows, so too does our need to store this energy to mitigate against troughs in supply. Energy storage in batteries or by conversion to chemical fuels are the two most flexible and scalable options, but are normally considered mutually exclusive. Energy storage solutions that can act as both batteries and fuel generation devices (depending on the requirements of the user) could therefore find great utility. In this talk, we shall investigate new device architectures for water splitting and energy storage that use Electron-Coupled-Proton Buffers (ECPBs) as redox mediators (see, for example: Nature Chem.
2013, 5, 403-409; Science,
2014, 345, 1326-1330; Joule, 2018, 2, 1390-1395) allowing high energy-density redox flow batteries and devices for the on-demand generation of hydrogen to be realised based on a common underlying chemistry (Nature Chem.
2018, 10, 1042-1047).

Figure 1
Nasicon Na3V2(PO4)3 Facilitates Anomalous Two-Stage Na+ and Zn2+ Intercalation for Zinc-Ion Batteries
Authors: Ko Jesse S. , Paul Partha P. , Seitzman Natalie , DeBlock Ryan , Dunn Bruce S. , Weker Johanna Nelson
Published: February 2020

Multivalent (MV) ion storage remains to be a key thrust in the development of prospective “beyond lithium-ion” technology. In the field of Zn2+-based MV batteries, lingering questions regarding Zn2+ intercalation remain due to the divalent nature of this positively-charged cation. In the present study, we explore the charge-storage properties of a V-based Na+ superionic conductor (NASICON), Na3V2(PO4)3 (NVP), by X-ray synchrotron characterization to unravel potential-dependent structure-property relationships. We posit that a two-stage intercalation of Na+ and Zn2+ may be responsible for the overall electrochemical behavior. The initial charging profile at C/20 indicates Na+ extraction from Na3V2(PO4)3 to NaV2(PO4)3, observed by a single plateau in the galvanostatic charge/discharge profile, while subsequent discharge results in two plateaus occurring at 1.35 and 1.2 V. Operando X-ray diffraction of the cells were collected to examine the changes associated with the first charge/discharge cycle, which showed reversible behavior based on the shifting of X-ray reflections associated with the NVP structure. To examine distinct changes linked with the suggested Na+ and Zn2+ two-stage intercalation process, electrodes were prepared ex situ for Rietveld refinement to understand variations in the lattice parameters. Furthermore, changes in V oxidation state, V-O coordination, and the presence of Zn2+ was studied by ex situ X-ray absorption spectroscopy. The results of this work present a rigorous analysis of the charge-storage property of MV Zn2+ intercalation for a well-established NASICON framework, and may provide further insight into the other related structures.
Nitrogen-Containing Organic Electrode Materials for Li-Ion Batteries and Beyond
Authors: Luo Chao , Wang Chunsheng
Published: February 2020

The commercial Li-ion batteries cause severe environmental challenges such as heavy metal pollution and global warming due to the use of toxic cobalt-based inorganic materials and the huge amount of CO2 release from the battery material production and recycling process. To overcome these environmental challenges, the inexpensive, abundant, environmentally benign and sustainable organic electrode materials and polymers provide an ideal solution. In our work, we demonstrated that the nitrogen-containing organic materials such as carboxylated azo compounds and imine-based polymers are promising electrode materials for Li-ion batteries and beyond. As an example, poly-hexaazatrinaphthalene (PHATN), which is an electron-deficient, rigid and planar aromatic discotic system with pyrazine functional groups, enables fast charge/discharge of Na, Mg and Al ions with high cycling stability. In Na-ion batteries (NIBs), PHATN delivers a reversible capacity of 165 mA h/g and 100 mA h/g after ultra-long 10,000 and 50,000 cycles at ultra-high current densities of 2 A/g (5C) and 10 A/g (25C), respectively. These capacity delivery and retention, to our best knowledge, are the highest among both organic and inorganic cathodes reported for NIBs. The exceptional rate and cycle life seen in NIBs carry over to RMBs and RABs as well. The mechanism for exceptional rate and cycling performance of PHATN is investigated using density functional theory (DFT), ex situ Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). For the first time, we proved that imine group (C=N) in the conjugated polymer can reversibly react with Mg2+ and Al3+ in the rechargeable batteries. This work demonstrates that the pyrazine-based polymer cathode is promising for developing environmentally benign, high-energy-density, fast and ultra-stable rechargeable batteries.