bluuebunny/crossref_metadata_2025 huggingface dataset:
Scale up of Proton-Conducting Ceramics into Multi-Cell Stacks
Authors: Le Long Quoc , Hernandez Carolina Herradon , O'Hayre Ryan , Sullivan Neal P
Published: December 2020

Proton-conducting ceramics are emerging as an enabling material for efficient electricity generation, energy storage, and fuels synthesis. While recent advancements at the lab-scale are highly encouraging, there are few reports of scaling cell size beyond the button cell, and no demonstrations of multi-cell stacks. Through support from the U.S. Department of Energy, researchers at the Colorado School of Mines are scaling up protonic-ceramic devices from the button-cell level into small, multi-cell stacks as illustrated in the figure. Both fuel-cell and electrolyzer stacks are in development. The order-of-magnitude increases in the physical size of the delicate membrane-electrode assembly (MEA) bring concerns regarding mechanical strength and robustness. The compatibility of protonic-ceramic materials with stack-packaging materials – metallic interconnects, current collectors, glass-ceramic sealants, and gaskets – has witnessed limited study. In this presentation, we describe selection and tuning of materials, fabrication procedures, and operating conditions to achieve reasonable performance and low degradation in protonic-ceramic fuel cells (PCFCs) stacks.

We find highest stack electrochemical performance and durability when utilizing electrolytes based on BaCe0.4Zr0.4Y0.1Yb0.1O3-d (BCZYYb). The anode support is a nickel-electrolyte composite, while the cathode is BaCe0.4Fe0.4Zr0.1Y0.1O3-d (BCFZY). The planar MEAs reach 5 cm2 in active area. The circular stack design enables a measure of flexibility in MEA physical size and shape, and provides balance in stress distribution from thermal- and chemical-expansion. The MEAs are packaged within ferritic-steel interconnects and macor frames to form multi-cell stacks. Our three-cell stack demonstrates encouraging performance, reaching 0.69 and 0.47 W cm-2 under H2 and CH4 fuels, respectively, at 600 ºC. A cathode-electrolyte interlayer of 10%-gadolinium-doped ceria proves critical in achieving stack degradation as low as 1.5% kh-1.

Figure 1
Photo-Enhanced Grain Boundary Ionic Conductivity in Gadolinium Doped Ceria
Authors: Klotz Dino , Defferriere Thomas , Gonzalez-Rosillo Juan Carlos , Rupp Jennifer L.M. , Tuller Harry L.
Published: December 2020

Oxide-based ionic and mixed ionic-electronic conductors (MIEC) play strategic roles in applications ranging from energy conversion and storage to thin film nano-ionic devices such as fuel cells, batteries, permeation membranes and nano-electronic memory and sensing devices. Most cost-effective production methods for fabricating both bulk and thin films samples generally result in the formation of polycrystalline microstructures with grain boundaries, where the crystallographic periodicity is interrupted.

Grain boundaries possess significantly different properties compared to the bulk and often block ion migration. Due to the high resistance and large activation energies, they represent a ubiquitous problem to overcome for a variety of electrochemical energy storage and conversion devices especially for low temperature applications. Space-charge potential barriers, featuring depletion zones and band bending, forming at the interface between adjacent grains, have been used to explain their blocking nature in polycrystalline semiconductors.

In the field of photoelectrochemistry, above band-gap light is well-known to contribute to reduce band bending at interfaces by providing additional charge carriers to screen potential barriers. Here, we show that the same principle can be applied to ionic conductors as well, and that we can significantly decrease the grain boundary impedance contribution in such systems.

We illustrate photo-enhanced ionic conduction in a thin film of 3% Gd-doped ceria upon illumination by UV light, whose photon energy is slightly above ceria’s band-gap. In fact, we demonstrate the ability to decrease the grain boundary resistance by 72% at 250°C and reduce its activation energy nearly in half from 1.12 eV in the dark to 0.68 eV under UV light illumination. We further demonstrate that this effect is not caused by heat, electronic conductivity, surface catalysis or other effects. Our findings are based on electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy (IMPS) measurements, performed on polycrystalline and epitaxial samples, and backed by theoretical considerations of grain boundary potential height and space charge regions.

This work was supported by JSPS Core-to-Core Program, A. Advanced Research Networks: “Solid Oxide Interfaces for Faster Ion Transport”, Department of Energy, Basic Energy Sciences and the Swiss National Science Foundation.

Figure 1
Ionic Conductivity of Protonated Layered Titanate Nano-Powder Compact in Water
Authors: Vediyappan Veeramani , Nomura Munemitsu , Lai Qiwen , Terayama Yuki , Fujisaki Takaya , Eguchi Hiroto , Yamauchi Miho , Sone Yoshitsugu , Mendoza Omar , Matsuda Junko , Satokawa Shigeo , Matsumoto Hiroshige
Published: December 2020

Ion-conducting materials are significantly important for electrochemical energy conversion. In particular, proton-conducting polymer electrolyte has been commercialized in a wide range of residential-type fuel cells and hydrogen fuel-cell vehicles. In the way, Nafion have been extensively used for polymer electrolyte membrane (PEM) fuel cell and water electrolysis, however, it has few drawbacks including high production cost, low proton-conductivities and low humidity at high temperature (>100 °C). Recently, huge research efforts have been focused on the investigation of a new proton conducting inorganic electrolyte materials as an alternative to polymer-based membranes. Hence, we have demonstrated that nano-powder of a layered protonated titanate (H2Ti2O5.H2O; LPT) compound exhibits a significant proton conductivity and that the conduction has been identified to take place on the surface of the nanoparticles in contact with water. The conductivity was measured on the compact of the un-milled/milled powder and it reached higher than 10-2 S cm-1 at 95 °C in water in the milled case. The increase in conductivity of LPT after bead milling along with the thermogravimetric and surface area analysis suggested that the protonic conduction takes place on the surface of the nanoparticles in contact with water. A linear relationship was found between the BET surface area and electrical conductivity, indicating that the majority of proton conduction take place on the surface of titanates nanoparticles. However, the conductivity of LPT was still low (~10-2 Scm-1) compared to conventional electrolyte materials, such as Nafion other high-performance polymer electrolytes (~10-1 Scm-1). Nevertheless, the present conductivity of LPT is equivalent to 100 mΩ at 10 µm thick per cm2, which is applicable to water electrolysis and fuel cells. This work has demonstrated a great potential of using cheap and inorganic LPT materials as electrolyte materials in energy conversion applications.

Figure 1
H-TEMP Outstanding Achievement Award Address Introduction
Authors: Gannon Paul , Kreller Cortney R.
Published: December 2020

Introductory remarks for the High Temperature Materials Division Outstanding Achievement Award Address.
Transition Metal Oxide/ Metal-Organic Framework Hybrid Structures for Efficient Bifunctional Oxygen Electrocatalysis in Alkaline Environments
Authors: Lee Min Hwan
Published: December 2020

Use of regenerative fuel cells (RFC) requires bifunctionality in oxygen electrocatalysis of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) to decrease weight and cost for efficient energy conversion. Many RFC based technologies have used noble metals such as Pt and its alloys (Pt/Ir or Pt/Ru) due to their efficient catalytic activity, selectivity and stability in harsh environments. However, their susceptibility to fast degradation during operation, as a result of catalyst agglomeration and poisoning, has driven research to find alternatives. Non-precious transition metal oxides (TMO) including Fe3O4, MnOx and Co3O4 have attracted significant attention as a potential candidate [1].

We utilized a hybrid structure where terephthalic acid ligand, cobalt and cerium nitrate salts, and solvents are subjected to a hydrothermal process at 160ºC for 24 h, a phosphoric acid treatment, an atomic layer deposition (ALD) of titania or zirconia, and finally a heat treatment in air. The phosphate group formed by the acid treatment is believed to have formed strong anchoring sites for ALD nanodots on the novel metal organic framework (MOF)-derived structure, which also results in a dispersed distribution of catalytically active sites.

The hybrid catalyst where TiO2 nanodots are uniformly anchored on phosphorylated MOF by ALD showed good ORR and OER performance in 0.1 M KOH in terms of onset/half-wave potential, electron transfer number, and current density when comparing to the performance of Pt/C (for ORR) and IrO2 (for OER). In addition, an activation of catalytic sites can be realized by a proper engineering of interfaces in each hybrid systems. Materials characterization emphasizes a strong adhesion of metal oxides upon MOF structures, thus providing ample surface interactions for favorable reaction route is important.

This project was funded by NASA Advanced STEM Training and Research (ASTAR) Fellowship.

References:

[1] G. Wu and P. Zelenay, Acc. Chem. Res., 46, 1878, 2013.
Data-Driven Development of Phosphors for LED Lighting
Authors: Brgoch Jakoah
Published: December 2020

The development of new phosphors that are necessary for the next generation of high efficiency LED lighting requires a unique approach for materials discovery. Researchers often rely on chemical substitution or serendipity to identify new materials; however, this inevitably leads to slow, incremental advances in technology development. Our work has recently created a new approach using data science and synthesis in tandem to produce new materials with impressive optical properties. Using data mining techniques, we extract experimental optical properties from the peer-review literature and then use these data to predict quantum yield, thermal quenching, and excitation and emission wavelength. Following this methodology, our research has developed several materials ranging from borates to nitrides. Moreover, the complementary use of computational modeling provides additional insight into the fundamental composition, structure, and property relationship, which is necessary for the continued advanced optical materials.
(Luminescence and Display Materials Division Centennial Outstanding Achievement Award Address) Investigation of Luminescent Materials based on First-principles Calculations of Multiplet States
Authors: Ogasawara Kazuyoshi
Published: December 2020

The transitions between multiplet states of rare-earth (RE) and transition-metal (TM) ions in crystals are utilized in variety of luminescent materials. Therefore, for the theoretical design of novel luminescent materials, a deep understanding of multiplet states and a nonempirical prediction of multiplet spectra are indispensable. For these purposes, a configuration interaction calculation program based on the discrete-variational Xa (DV-Xa) molecular orbital method [1] was developed, which is known as the discrete-variational multi-electron (DVME) program [2]. There is also a relativistic version of the DVME program [3] based on the relativistic DV-Xa method [4], which is especially useful for the analysis of RE-doped luminescent materials [5] since both the relativistic effects and the many-electron effects can be considered simultaneously without any empirical parameters. The DVME calculations have been applied to analyze various luminescent materials such as ruby [2], Mn4+-doped fluorides [6] and RE-doped LiYF4 [5]. Various types of multiplet spectra originating from d-d, f-f, f-d, and charge transfer (CT) [7, 8] transitions have been reproduced without any empirical parameters and the origins of the spectral peaks have been elucidated based on the configuration analysis of the explicitly obtained many-electron wave functions. In addition, relationships between the multiplet energy and the local structure of TM ions in crystals have been investigated in detail by creating various energy-structure maps based on systematic DVME calculations. The systematic data obtained by first-principles calculations can be also used as the training data for machine learning to create a simple predictive model. In this lecture, some representative results of the investigation of luminescent materials based on first-principles calculations of multiplet states using the DVME program will be presented.

[1] H. Adachi, M. Tsukada, and C. Satoko, J. Phys. Soc. Jpn., 45, 875 (1978).

[2] K. Ogasawara T. Ishii, I. Tanaka, and H. Adachi, Phys. Rev. B, 61 143 (2000).

[3] K. Ogasawara, T. Iwata, Y. Koyama, and T. Ishii, I. Tanaka, and H. Adachi, Phys. Rev. B, 64, 115413 (2001).

[4] A. Rosén, D.E. Ellis, H. Adachi, and F.W. Averill, J. Chem. Phys., 65, 3629 (1976).

[5] K. Ogasawara, S. Watanabe, H. Toyoshima, M.G. Brik, Handbook on Physics and Chemistry of Rare Earths, 37, 1 (2007).

[6] M. Novita, T. Honma, B. Hong, A. Ohishi, K. Ogasawara, J. Lumin. 169, 596 (2016).

[7] S. Takemura, K. Ogasawara, Opt. Mater.: X, 1, 100005 (2019).

[8] S. Takemura, K. Ogasawara, J. Lumin. 214, 116542 (2019).
IR Laser Induced Emission Spectra of GaN Nanoceramic
Authors: Stefanski Mariusz , Gluchowski Pawel , Strek Wieslaw
Published: December 2020

Currently, the researchers from around the world pay a lot of attention to search new white light generation sources. Such a device would have huge application potential in the lighting industry. The advantage of a broadband white light source is no necessity to mix few emission lines to obtain a white luminescence, as it is in case of the LED devices. Here, we investigate the broadband laser induced emission spectra of GaN nanoceramic measured under three different infrared excitation lines (1064, 975 and 808 nm). The GaN powder was obtained by thermal decomposition method while the nanoceramic was prepared using low temperature high pressure (LTHP) technique. The sample crystallizes in the hexagonal wurtzite structure and theoretical value of their average grain size calculated using Scherrer equation was 12 nm. The optical characterization of LIE spectra of GaN nanoceramic included the measurements of emission intensity as a function of power density, ambient pressure and luminescence kinetics. The emission spectra were recorded in both VIS (400-900 nm) and NIR (1200-2500 nm) regions (Fig. 1a,1b). It was found that the power dependence exhibit threshold behavior typical for avalanche process for all three excitation lines. The luminescence kinetics measurements show that rise and decay times of LIWE are extremely short in comparison to dielectric materials. It turned out that calculated x and y parameters of recorded emissions lie in the warm region of the CIE chromaticity diagram confirming their low color temperature regardless of the excitation wavelength (Fig. 1c). Finally, a general mechanism of LIE spectra in GaN nanoceramic is discussed.

Figure 1. The LIWE intensity of GaN nanoceramic under 975 nm as a function of increasing pumping power density in VIS and NIR regions (a,b). The CIE chromaticity diagram of LIWE generated from GaN nanoceramic upon three various excitation wavelengths (c). The image of LIWE during experiment (d).

Figure 1
The Effect of Anode Slippage on Cathode Cutoff Potential and Degradation Mechanisms in Ni-Rich Li-Ion Batteries
Authors: Dose Wesley , Xu Chao , Grey Clare P. , De Volder Michael F. L.
Published: December 2020

High energy-density Li-ion batteries based on Ni-rich layered cathodes are the state-of-the-art technologies for electric vehicles. However, batteries using these advanced cathode materials suffer from rapid performance fading and the underlying mechanisms are not fully understood.1 In this work, we report a critical turning point during the aging of graphite/LiNi0.8Mn0.1Co0.1O2 (NMC811) full cells after which the degradation is significantly accelerated. This turning point is identified using differential voltage analysis (DVA)2 applied to standard two-electrode full cell data, which shows a decreased capacity usage of the graphite with cycle number. The graphite becomes progressively less lithiated, as confirmed by operando long-duration X-ray diffraction, and therefore has higher electrochemical potential when the cell has reached the end of charge. As the upper cutoff voltage of the full cell is fixed, this increase leads to a proportional raise of the cathode potential and an accelerated impedance increase is observed from this point. This mechanism is expected to be universal for the vast majority of today’s Li-ion battery chemistries, particularly for Ni-rich cathodes whose degradation is shown to be extremely sensitive to the upper cutoff voltage, and our work provides fundamental guidelines for developing effective countermeasures.

References

Jung, M. Metzger, F. Maglia, C. Stinner, H. A. Gasteiger, J. Electrochem. Soc., 164, A1361, 2017.

Bloom, A. N. Jansen, D. P. Abraham, J. Knuth, S. A. Jones, V. S. Battaglia, and G. L. Henriksen, (2005). J. Power Sources 139, 295 2005.
A New Glass Forming Electrolyte Based on Lithium Glycerolate
Authors: Pagot Gioele , Di Noto Vito , Vezzu Keti , Nale Angeloclaudio , Negro Enrico , Pace Giuseppe
Published: December 2020

The study of the interplay between structure and conductivity in lithium-conducting electrolytes is a pivotal point for the development of future secondary batteries [1]. The use of Glycerol as a low molecular weight component in electrolytes is particularly interesting due to its glass-forming behavior and low glass transition temperature (-78.5°C). In addition, a high flexibility of the alkyl backbone chain and the well-known capability of oxygen functionalities to coordinate lithium cations make Glycerol very appealing as ion-conducting media as well as building block to obtain hybrid polymer electrolytes [2].

On this basis a family of eleven electrolytes based on Lithium Glycerolate with general formula C3H8-xO3Lix, where 0 ≤ x ≤ 1, is prepared and investigated [3]. In these electrolytes the Glycerolate (C3H8-xO3
x-) component acts as a large and flexible macro-anion which is able to provide a high single-ion conductivity to the material (8.36∙10-5 S∙cm-1 at 20°C and 1.55∙10-2 S∙cm-1 at 150°C for x = 0.25).

Finally, the Glycerol∙∙∙Li+ interactions in these electrolytes are studied on T and x, with a particular reference to the detection of: a) macro-anion coordination sites; and b) the secondary structure of Glycerol chains. Insights on the long-range charge transfer mechanism and Glycerol relaxation events are also discussed.

These studies are carried out by Inductively-Coupled Plasma Atomic Emission Spectroscopy, IR and Raman spectroscopies, DSC, TGA, and Broadband Electrical Spectroscopy.

References

[1] V. Di Noto, S. Lavina, G. A. Giffin, E. Negro, B. Scrosati, Electrochim. Acta 57 (2011) 4-13.

[2] V. Di Noto, M. Vittadello, S. G. Greenbaum, S. Suarez, K. Kano, T. Furukawa, The Journal of Physical Chemistry B 108 (2004) 18832-18844.

[3] G. Pagot, S. Tonello, K. Vezzù, V. Di Noto, Batteries 4 (2018) 41.
Ceramic-Coated Separator Containing Reactive Alumina As a Cross-Linker for in-Situ Gel Electrolyte Formation in Lithium-Ion Battery
Authors: Kim Hye-Min , Ahn Junhwan , Lee Young-Jun , Kim Dong-Won
Published: December 2020

Lithium-ion battery (LIB) has been used in many applications such as electric vehicles and electric power storage system over decades owing to its high energy density and good cycle life. As the demand for high energy density lithium-ion batteries is rapidly growing, safety issues have been derived imperatively. A separator plays a key role in cycling performance and battery safety. Separators should prevent short circuits by physical contacts between cathode and anode. However, commonly used polyolefin separators such as polyethylene (PE) and polypropylene (PP) do not have thermal resistance at high temperature over 150 oC. A lot of studies have dealt this critical safety concern by coating thermally stable materials such as ceramic particles and heat- resistant polymers onto the separator. In this work, the reactive alumina nanoparticles as a cross-linker were coated onto the PE separator to promote the radical reaction with cross-linking agent in the electrolyte as well as improve the thermal stability. The reactive alumina-coated separators allowed to maintain good interfacial contacts between separator and electrodes during the repeated cycling. As a result, the lithium-ion cells assembled by in-situ cross-linking using reactive alumina-coated PE separator exhibited good cycling performance and enhanced safety, as compared with the LIB employing PE separator and liquid electrolyte.
TiO2-Core/Sn-Shell Nanotube Arrays Based on Monolithic Negative Electrode for Lithium Ion Batteries
Authors: Kim Hyunsik
Published: December 2020

The next generation of lithium ion batteries will expand the application range from popular portable devices to high power electric vehicle and so on. For such a use, the cost factor and battery performance in safety, specific capacity and kinetics must be considered and improved. So far as it goes, carbonaceous insertion materials remain leading products for anode materials of lithium ion batteries. However, their reversible capacities are limited to below 372 mAh/g and the kinetic behaviours are also not satisfying. Under such a situation, new anode materials with higher capacity are required.

Recently, one-dimensional (1D) nanostructured materials have received increasing attention in the field of lithium-ion batteries due to large surface-to-volume ratio and contact area between the electrode and electrolyte, which can decrease the electron transport time for both lithium ions and electrons. Furthermore, it can accommodate the strain of lithium ion lithiation/delithiation, enhancing the high capacity and rate capability. Among them, the self-ordered TiO2 nanotubes with high surface-to volume ratios have been extensively examined using electrochemical anodization. These materials are expected to be anode material as a low voltage insertion host of Li and fast Li insertion/extraction host. However, the discharge/charge voltage curves of TiO2 nanotubes were suppressed by their conductivity with low degree. In order to improve the conductivity of TiO2 nanotubes, the carbon doping by the pyrolysis of C2H2 gas was performed. Also, Sn/TiO2 composite duplex nanotube is prepared by sputter method to enhance total discharge capacity and its electrochemical performance was evaluated by constant current discharge/charge, cyclic voltammetry, and electrochemical impedance spectroscopy.
The Role of TiO2 Particles on the Ion Conduction Mechanism in Polyether Electrolyte Having Cyanoethoxy Sidechain
Authors: Hitaka Tasuku , Isobe Ryutaro , Matsuoka Riho , Yamada Koki , Sai Ryansu , Katayama Yu , Tsutsumi Hiromori
Published: December 2020

Although solid-state polymer electrolytes (SPE) have attracted much attention as a safe electrolyte material for lithium-ion batteries (LIB), one major limitation of SPE resides in the low ionic conductivity[1]. Previous study reported the improvement of ionic conductivity by adding inorganic particles into polymer electrolytes[2]. However, a molecular-level understanding of its effect on the Li+ conduction mechanism is still lacking.

In this study, we select polyether having cyanoethoxy sidechain as a polymer matrix, and clarify the effect of TiO2 nanoparticles on the Li+ conduction mechanism. Differential scanning calorimetry and thermogravimetric analysis confirmed that glass transition temperature (T
g) and the thermal stability of electrolytes were not affected by TiO2. On the other hand, electrolyte with TiO2 showed higher ionic conductivity than the electrolyte without TiO2. Various (electro)chemical and spectroscopic analyses were performed to clarify the key descriptor for the ionic conductivity. Infrared spectroscopy confirmed that the Li+–CN interaction was not affected by the existence of TiO2. However, it also suggested two types of the dissociated anion (free anion and anion interacting with the surface hydroxyl group on TiO2) in the electrolyte with TiO2. Based on these results, observed improvement of Li+ conduction for TiO2-contained electrolytes can be due to the trapping of bulky anion by surface hydroxyl groups on TiO2.

In conclusion, we clarify that the anion trapping by the surface hydroxyl group on TiO2 nanoparticles could facilitate Li+ conduction, probably due to the absence of bulky anion, which sterically inhibits Li+ transportation. The surface hydroxyl groups on inorganic fillers thus play a vital role in facilitating Li+ conduction.

[1] X. Zhigang et al., J. Matter. Chem. A, 2015, 3, 19218–19253.

[2] F. Croce et al., Nature, 1998, 394, 456–458.
Effects on Interfacial Resistance Using LICGCTM in the Cathode
Authors: Katoh Takashi , Satoh Ryouhei , Nakajima Kousuke , Hoffman Brion
Published: December 2020

Lithium ion batteries are widely used in electric devices and electric vehicles due to their excellent performance at high power and the high energy density they provide compared to other conventional batteries. The application for electric vehicles is expanding worldwide as our society moves towards a lower carbon footprint but the lithium ion battery technology still needs further improvements in terms of physical properties, output, durability and safety. Current lithium ion batteries also degrade with charge–discharge cycles and storage time. In the cathode, low retention capacity, accompanied by the growth of resistive thin films and crystal structure deterioration on the surface of the active materials, remain unsolved problems. Modifications to the cathode surfaces have been researched and proven as effective measures to improve durability. Surface coatings on lithium‐ion battery cathodes improve their durability. Solid oxide materials like MgO, ZrO2 and SiO2 are applied or processed on to the cathode active materials by sol-gel, PVD or mechanochemical treatments and the solid oxide layer plays a role as an artificial solid electrolyte interface. The solid oxide coating layer prevents contact between the electrolyte and the active materials thus inhibiting the redox process and leading to an improvement in the cycle performance of the battery.

We confirmed the LCO cathode containing a small % of Ohara lithium ion glass ceramic (LICGCTM ) PW-01 powder showed less deterioration and transition metal reduction at high temperature (60℃). The LICGCTM PW-01 powder was produced using a glass melting and ceraming method. A Li 2O-Al 2O 3-TiO 2-P 2O 5 glass was prepared and converted into glass-ceramics through heat-treatment. The lithium ion conductivity of the glass-ceramic with Li 1 + x
Al
x
Ti 2 − x
(PO 4) 3 phase is extremely high 1 × 10 −3 Scm −1 at room temperature. We found that adding LICGCTM PW-01 powder in the cathode had other significant effects, including increasing the battery capacity at high rate and at low temperature (-20℃). We also verified via by EIS measurement that the LICGCTM PW-01 powder additive significantly reduced the charge transfer resistance. The use of the LICGCTM PW-01 powder as a cathode slurry additive can serve an important role in improving the performance of lithium ion batteries.
Why Dimethyl Carbonate Is Better Co-Solvent Than Other Linear Carbonates: Important Role of Polar Conformer Formation
Authors: Lee Hyejin , Hwang Sunwook , Lee Hochun
Published: December 2020

The underlying nature of the ion conduction in concentrated battery electrolytes still remains elusive. An archetypal example is a long-standing puzzle why a dimethyl carbonate (DMC) solution exhibit higher ionic conductivity than other linear carbonate (LC) solutions despite the similar physicochemical properties of the LC solvents. To address this, we investigate the correlation between the conformation isomer formation and salt dissociation behavior in 0.1 M–3.0 M LiPF6 DMC, ethyl methyl carbonate, and diethyl carbonate solutions using Raman spectroscopy, dielectric relaxation spectroscopy, and pfg-NMR. Importantly, we corroborate that compared to the other two LCs, DMC more readily dissociates Li-salt into free, conducting ions. The higher salt-dissociation ability of DMC was attributed to the extensive formation of polar cis-trans conformer participating in Li-ion solvation compared to non-polar cis-cis conformer. This study unveils the critical role of the solvent isomerism in the ion-solvation chemistry, suggesting an avenue to achieve highly conductive electrolytes for rechargeable batteries.
Three-Dimensional Resistivity Quantification and Visualization of Silicon-Based Composite Anode Nanostructure Via Scanning Probe Microscopy
Authors: Stetson Caleb , Downard Ali , Huey Zoey , Jiang Chun-Sheng , Al-Jassim Mowafak M. , Finegan Donal , Han Sang-Don , DeCaluwe Steven C.
Published: December 2020

Nanocomposite Si-graphite electrodes are a viable option for increasing the energy density and life of lithium-ion battery anodes. In comparison to model systems (e.g., Si wafer and Si thin film), Si nanoparticles, ranging in diameter from tens to hundreds of nanometers, have higher rate capacity and improved fracture toughness.1, 2 However, characterization efforts to better understand localized degradation mechanisms and heterogeneous aging behaviors of distinct components—Si, graphite, binder, and conductive carbon—in Si-based nanocomposite anodes through cycling are hindered by the limited information that can be achieved at the nanoscale using traditional microscopy techniques.

To date, high resolution, three-dimensional structural visualization of the Si-based composite electrode has relied upon techniques like X-ray nano-computed tomography3, 4, that provide morphological information but not electronic or chemical information. In this work, we report a novel lab-scale scanning probe microscopy-based approach to map the 3-D nanostructure of composite anodes via contrast in their components’ intrinsic electronic properties. By incorporating experimental nanoscale electronic resistivity data through interpolation, volumes can be extracted to represent distinct constituent phases of the composite electrode. This approach presents an opportunity for relatively high throughput, nanoscale characterization of composite anodes and cathodes to investigate phenomena such as particle dispersion in electrode preparation and electrode evolution through cycling. Ultimately, this technique shows future utility for the multiscale understanding of structural evolution and degradation processes within lithium-ion batteries.

Figure 1: Interpolated resistivity layers captured within a Si-Carbon(C) composite electrode, processed to extract C-rich and Si-rich volumes.

R. C. de Guzman, J. Yang, M. M.-C. Cheng, S. O. Salley, and K. Y. Simon Ng, Journal of Materials Science,
48 (14), 4823-4833 (2013).

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12 (2), 303-306 (2010).

O. O. Taiwo, M. Loveridge, S. D. Beattie, D. P. Finegan, R. Bhagat, D. J. L. Brett, and P. R. Shearing, Electrochimica Acta,
253 85-92 (2017).

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3 (10), (2019).

Figure 1
Chemistry, Microstructure, and Interphases of Magnesium Metal Anodes Captured Via Cryogenic Electron Microscopy
Authors: Long Daniel M , McClary Scott A , Hahn Nathan T , Zavadil Kevin R , Jungjohann Katherine L
Published: December 2020

Lithium-ion batteries are an important component in mobile electronics; however, their modest energy density makes them less than ideal for use in all-electric vehicles or localized grid residential/commercial energy storage. Multivalent-ion batteries (MIBs), including Mg2+, are promising high-energy density technologies that are cheaper and more abundant than lithium. Realizing the high theoretical energy density of MIBs requires the native multivalent-ion metal to be used as the anodic electrode, where densely controlled metal plating and stripping has yet to be achieved. The mechanisms governing plating/stripping of MIBs and the resulting microstructural impact on the battery performance must be understood before MIBs can be employed commercially. Understanding the role that the solid electrolyte interface has on multivalent-ion metal plating/stripping may lead to solutions for controlling reversible anodic cycling.

Recent advances in cryogenic electron microscopy(cryo-EM) preparation have allowed for scanning transmission electron microscopy (STEM) investigation of intact solid/liquid interfaces and electron-beam-sensitive materials. Here we present results of our chemical and microstructural investigation of plated and stripped Mg2+ anodes, collected with cryo-FIB preparation, cryo-transfer, and cryo-STEM. Details will be presented on the anode porosity, grain orientation maps, chemical maps from the electrode/electrolyte interfaces, and high-resolution structural imaging of the electrode interfaces.

This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.
The Effect of Temperature and SEI Formation on the Nucleation and Growth of Electrochemically Plated Lithium
Authors: Sandoval Stephanie , Klein Emily J , Shetty Pralav P , Thenuwara Akila C , Cavallaro Kelsey A , McDowell Matthew T
Published: December 2020

Understanding the nucleation and growth process during electroplating of lithium metal is essential for enabling long cycle life in lithium metal batteries. The morphology of electrochemically plated lithium is strongly correlated with Coulombic efficiency and cycle life, and the nucleation and growth of lithium is dictated by the nature of the substrate, the characteristics of the solid electrolyte interphase (SEI), and temperature. However, there is a lack of knowledge about how these factors affect fundamental nucleation and growth processes, especially at temperatures other than room temperature. In this work, we investigate the nucleation, growth, and morphology evolution of lithium metal under different temperature conditions. Stainless steel and antimony metal are used as substrates to compare growth surfaces that are inert with those that form alloys with lithium. Ex situ SEM is used to explore the morphology evolution at temperatures ranging from -20 °C to 20 °C. In order to better track the particle size evolution over time, we use an electrolyte solution tailored to cause Li to deposit as spherical particles (a 1:1 (v/v) 1,3-dioxolane (DOL) and 1,2 dimethoxyethane (DME) mixture with 1M LiTFSI and 0.8M LiNO3). We find that as temperature increases, the particle size also increases. Furthermore, growth on lithiated antimony films results in larger average particle sizes than on stainless steel. Our experiments also show that the extent and nature of the initial SEI growth on the substrate plays a controlling role in determining the Li morphology and uniformity of growth, and prolonged growth of the SEI was found to increase the Coulombic efficiency during the first few cycles. These results highlight the sensitivity of Li to cycling conditions and temperature, and they indicate that careful control is necessary to attain high-efficiency cycling in Li metal batteries.
Nano-Thin TiO2 Layer Coating By Polydopamine Pre-Coating for Highly Stable Ni-Rich Layered Oxides with 4.5 V High-Voltage Operation in Lithium-Ion Batteries
Authors: Kim Hyeongwoo , Jang Jihye , Byun Dongjin , Choi Wonchang , Kim Hyungseok
Published: December 2020

As the demand for electric vehicles or large-scale energy storage system increases rapidly, high-energy and stable lithium-ion batteries (LIBs) have been required. Accordingly, a large attention has been paid to Ni-rich layered oxides which has a higher energy density than LiCoO2, and the Ni-rich layered oxides have been applied to cathode materials for LIBs. Although the researchers succeeded in obtaining high reversible capacity by increasing the Ni content, the higher Ni content in layered oxides is still structurally unstable, which seriously degrades the cycling stability and lefts many questions on a reliability of the LIBs. Generally, the cycle degradation is mainly related to surface degradations which can be ascribed to side-reaction products and NiO formation from the oxidation of the electrolyte, and these are caused by the generation of highly reactive Ni4+ ions during charging to high-voltage (≥4.3 V). These surface degradations are accelerated when the cell is operated at high temperature, those side reactions at the electrode/electrolyte interface and structural degradation are seriously worsen. To solve the problem, coating strategy is effective way to mitigate the surface degradation, and the uniformly coated layer can can suppress the side reaction effectively for each particle. However, conventional coating methods such as ball-milling or wet coating have a limitation to achieve the uniformity of the coating layer due to the lack of the driving force for making the coating material concentrated on the whole surface.

In this study, a stable Ti-based oxide coating layer is introduced on LiNi0.6Co0.2Mn0.2O2 (NCM). To obtain a nano-thin uniform coating layer based on the driving force, concentrating the coating material, we coated the polydopamine (PDA) on the NCM first to trap Ti4+ ions on the surface in the coating solution through forming O-H catechol groups. This helps to attract Ti(OEt)4 molecules to the NCM surface, thus uniform TiO2 nanolayer can be obtained after the calcination process. The TiO2 nanolayer suppresses side reactions with the electrolyte generated during the charging process to improve the surface stability. We confirmed the growth of CEI (cathode electrolyte interphase) layer originated from side reactions during the cycling through XPS and TEM analyses Consequently, it enhances the cycling stability in the high-voltage operation (4.5 V), and it also improves the high temperature (60 oC) cycling. In summary, this talk will give a facile way to form a uniform and ultrathin TiO2 nanolayer on Ni-rich oxide surface by pre-coating a polydopamine layer. We expect that the PDA pre-coating method is effective and could be applied to other fields where high-quality coating is required.

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High Transference Number of Na Ion in Highly Concentrated Nan(SO2F)2/γ-Butyrolactone Electrolytes for Sodium Batteries
Authors: Dokko Kaoru , Nishimura So , Okamoto Yukihiro , Tatara Ryoichi , Ueno Kazuhide , Watanabe Masayoshi
Published: December 2020

We report here the liquid structures and physicochemical properties of highly concentrated solutions of NaN(SO2F)2 (NaFSA) dissolved in γ-butyrolactone (GBL) for Na-ion batteries. The solvation structure of Na+ was analyzed using Raman spectroscopy. By adding NaFSA to GBL, the Raman band of ring stretching vibration (678 cm−1) of GBL shifted to higher wavenumber because the GBL coordinates to Na+ ion. The concentration dependence of Raman spectral change of GBL suggested the solvation number of Na+ is 5 when the excess GBL molecules exist in the solution. As increasing the concentration of NaFSA, the bound GBL increases and free GBL decreases. At higher concentration of [NaFSA]/[GBL] > 1/2, free GBL does not exist and all of the GBL molecules coordinate to the Na+ ion. Raman spectra of FSA anion suggested that the FSA anion also participates in the coordination of Na+ in the highly concentrated solution. Apparently, the contact ion pairs and ionic aggregates are formed extensively in the highly concentrated solution. This gives significant effects on the Na+ ion conduction mechanism in the liquid. We estimated the transference number of Na+ ion in the electrolytes. The transference number of Na+ in the liquid of [NaFSA]/[GBL] = 1/1 was as high as 0.7. This surprisingly high transference number is probably due to the peculiar conduction mechanism in the ionic aggregates. Na+ ion is considered to exchange the anions dynamically in the ionic aggregates, and this may induce the hopping conduction in the liquid. Charge and discharge tests of a hard carbon electrode were conducted in the liquid of [NaFSA]/[GBL] = 1/1, and the reversible Na+ insertion/extraction into/from the electrode were possible with a high coulombic efficiency. The SEI derived from the FSA anion might contribute to the reversible electrochemical reaction.

Acknowledgements

This study was supported in part by JSPS KAKENHI (Grant Nos. 18H03926 and 19H05813) from the Japan Society for the Promotion of Science (JSPS) and the MEXT program “Elements Strategy Initiative to Form Core Research Center” of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan.
Novel Bulky Lithium Salts and Their Electrolytes for Safer Solid-State Lithium Metal Battery
Authors: Nguyen Thi Khanh Ly , Yver Clémence , Devaux Didier , Alloin Fannie , Gigmes Didier , Phan Trang N.T. , Bouchet Renaud
Published: December 2020

In recent years, Lithium metal batteries (LMBs) have gained great interests thanks to their high capacity that can respond to the continuous increasing need for energy storage and device. The design and development of new solid-state electrolytes e.g. polymer based ones (SPEs) then became crucial towards intrinsically safer LMBs. A successful electrolyte candidate needs to fulfill several requirements such as high transference number (tLi
+) and a compromise between two antagonist properties: conductivity and mechanical properties. Most researches focused on the synthesis of single-ion conducting electrolytes as a strategy to overcome these difficulties1,2. However, these materials often require complicated and delicate chemistry and their conductivity often remains low (σ < 10-5 S/cm at 60°C). An alternative promising route that received much less attention is the development of bulky Lithium salts with macroanion. The bulky anion reduces ion paring and salts aggregation and present negligible mobility compared to Lithium cation resulting in higher transference number3.

In this work, we present a new macroanion based on Polyhedral Oligomeric Silsesquioxane (POSS) grafted with either polyethylene oxide oligomers (PEG) and/or Lithium sulfonyl (trifluoromethanesulfonyl) imide (LiTFSI) denoted as POSS-LiTFSI-PEG or POSS-LiTFSI respectively. Thus, SPE has been prepared with a reference high molecular weight polyethylene oxide at different OE/Li ratio from 10 to 25. This new concept of bulky multi-anion based on TFSI moieties allows a complete salt dissociation, an enhancement of the mechanical properties thanks to the presence of the inorganic POSS multi anions that play the role of nano fillers, and finally, a strong increase of the Li+ transference number (tLi+>0,55), which opens many perspectives. The cycling performance obtained in both Lithium symmetric cells and LMBs prototypes will be also presented.

References

(1) Bouchet, R.; Maria, S.; Meziane, R.; Aboulaich, A.; Lienafa, L.; Bonnet, J.-P. P.; Phan, T. N. T.; Bertin, D.; Gigmes, D.; Devaux, D.; et al. Single-Ion BAB Triblock Copolymers as Highly Efficient Electrolytes for Lithium-Metal Batteries. Nat. Mater.
2013, 12 (5), 452–457.

(2) Zhang, H.; Li, C.; Piszcz, M.; Coya, E.; Rojo, T.; Rodriguez-Martinez, L. M.; Armand, M.; Zhou, Z. Single Lithium-Ion Conducting Solid Polymer Electrolytes: Advances and Perspectives. Chem. Soc. Rev.
2017, 46 (3), 797–815.

(3) Chinnam, P. R.; Wunder, S. L. Polyoctahedral Silsesquioxane-Nanoparticle Electrolytes for Lithium Batteries: POSS-Lithium Salts and POSS-PEGs. Chem. Mater.
2011, 23 (23), 5111–5121.

Figure 1
Systems-Level Investigation of Aqueous Batteries for Understanding the Benefit of Water-in-Salt Electrolyte By Synchrotron Nano-Imaging
Authors: Lin Cheng-Hung , Sun Ke , Ge Mingyuan , Housel Lisa M. , McCarthy Alison H. , Vila Mallory N. , Zhao Chonghang , Xiao Xianghui , Lee Wah-Keat , Takeuchi Kenneth J. , Takeuchi Esther S. , Marschilok Amy C. , Chen-Wiegart Yu-chen Karen Karen
Published: December 2020

The concept of “Water-in-salt” (WIS) electrolyte enabled the application of higher voltage aqueous battery, overcoming the limitation of the narrow voltage window of water (~1.23V) for better safety and environmental sustainability. Recent work in the field has been exploring the electrochemical performance of batteries using WIS electrolytes with different electrode couples as well as the intrinsic electrochemistry and physical chemistry properties of WIS electrolytes. In this work, LiV3O8 anode and LiMn2O4 cathode for aqueous Li-ion batteries are coupled to investigate the mechanism by which WIS electrolyte improves the cycling stability at an extended voltage window. The study probed the morphological evolution of the active electrode particles as a function of the electrochemistry. While delaying the water decomposition process, the WIS electrolyte improves the cycling stability of the battery by suppressing the mechanical damage to the electrode network and dissolution of the electrode particles through the operando observation under synchrotron transmission X-ray microscopy on the LiMn2O4 cathode. As the viscosity of WIS is significantly higher, the reaction heterogeneity of the electrodes cycled with WIS electrolyte is quantified with X-ray absorption spectroscopic imaging, visualizing for the first time the kinetic limitations of the WIS electrolyte. This work furthers the mechanistic understanding of electrode – WIS aqueous electrolyte interactions and paves the way to explore the strategy to mitigate their possible kinetic limitations in 3D architectures.

Figure 1