bluuebunny/crossref_metadata_2025 huggingface dataset:
Are Protons Involve in the Fading Capacity in Li Ion Aqueous Batteries? Shedding Light By Means of First Principle Computations
Authors: Posada Pérez Sergio , Rignanese Gian-Marco , Hautier Geoffroy
Published: May 2020

Commercial lithium ion batteries are composed of an anode based on carbon, a transition metal oxide cathode separated by an organic liquid electrolyte containing a lithium salt such as LiPF6. Nevertheless, operating with an organic electrolyte presents many drawbacks. The organic electrolyte is flammable, expensive and need to be kept away from any water contamination. On the other hand, working in aqueous electrolyte would therefore be extremely beneficial especially to lower production cost and obtain higher safety and lower toxicity. The performance of aqueous based LIBs has been demonstrated since the foundational work from Dahn et al. who combined an anode of VO2 and a cathode of LiMn2O4 in an aqueous electrolyte.

In contrast to organic electrolytes, where only the inserted metal ions can (de)intercalate in the electrode material, the use of aqueous electrolytes opens the possibility of proton co-insertion. Proton intercalation has been one of the common assumptions to explain performance issues in aqueous electrolytes such as capacity fading and the increase in lithium diffusion barriers. Several (electro)chemical studies combined with first-principles computations have confirmed the easy protonation of layered electrodes at different ranges of pH values and this fact has been directly related with the detrimental in cathode materials. Nevertheless, several studies reported the excellent performance of layered LiCoO2 and LiCo1/3Ni1/3Mn1/3O2 as positive electrode -without coating- using neutral or basic salt in water electrolytes. Thus, it remains an open question: Why these layered cathode materials so prone to proton intercalation could perform as well in aqueous environment?

In this work, we use density functional computations to investigate the lithium/proton exchange in some well-known cathode materials. The analysis of the proton insertion mechanism has been carried out in order to demonstrated which specific chemical and structural features lead to electrochemically stable materials for aqueous batteries. To analyze the Li+/H+ exchange, several Li+/H+/vacancy orderings and arrangements were computed to study the phase stability at different pH values.

Given that the importance of proton insertion for aqueous batteries, this study provides fundamental investigations about the role of H-intercalation in the performance of aqueous battery operations.
Nanostructured NCA As a Fast Charging High Rate Cathode Material for Lithium-Ion Batteries
Authors: Basile Victoria M. , Lai Chun-Han , Butts Danielle M. , Dunn Bruce S. , Tolbert Sarah H.
Published: May 2020

Lithium-ion batteries are commonly used in personal electronics such as cell phones and larger electronics such as electric cars. In order to charge these devices on the order of minutes instead of hours, fast charging lithium-ion batteries are needed. Pseudocapacitive charge storage is a potential solution because it allows for intrinsically fast charging/discharging, while retaining high energy density. Some materials can transition from battery-like to pseudocapacitive charge storage upon nanostructuring, which decreases the particle size, therefore decreasing the lithium-ion diffusion length. Here we are studying nanostructured NCA (LiNi0.80Co0.15Al0.05O2) with pseudocapacitive metrics to guide our work on high rate cathodes. NCA is a layered transition metal oxide cathode material, that already shows promising fast cycling in the bulk due to suppression of intercalation-induced phase transitions. By nanostructuring NCA, we can shorten the lithium-ion diffusion length for faster charging/discharging. Nanostructured NCA was synthesized using a colloidal polymer templating technique followed by either traditional slow heating or rapid thermal annealing, which resulted in either medium (~300 nm) or small (~150 nm) particle sizes, respectively, both of which are significantly smaller than standard commercial bulk NCA. All samples showed linear voltage profiles (Fig. 1), indicative of pseudocapacitive charge storage, but the smaller materials showed much higher capacity at high rates. The medium domain sized material has 6x higher specific capacity compared to the bulk material at 64 C, ~1 min charge/discharge (Fig. 1). Interestingly, while we would expect the smallest sized particles to have the highest capacity at 64 C, they are instead intermediate (Fig. 1). Apparently the short heating times required to obtain the small particle size material resulted in less perfect crystals and thus lower diffusion rates. These results thus help illustrate how optimizing high rate nanostructured NCA requires a balance between lithium-ion diffusion rate and total diffusion distance.

Figure 1
High Transference Number of Na Ion in Highly Concentrated Sodium Bis(fluorosulfonyl)Amide/γ-Butyrolactone Electrolytes for Sodium Batteries
Authors: Dokko Kaoru , Nishimura So , Okamoto Yukihiro , Tatara Ryoichi , Ueno Kazuhide , Watanabe Masayoshi
Published: May 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.
(Invited) Layered Sodium Transition Metal Oxides As Cathode Materials for Na-Ion Batteries
Authors: Lee Kyu Tae
Published: May 2020

Thanks to their excellent electrochemical performance, Li-ion batteries have been successfully utilized as a power source in electric vehicles and large-scale energy storage systems. However, there are some concerns that the current technology of Li-ion batteries is not able to meet the demands for power sources in future energy storage applications. For example, lithium resources are expensive and too geographically constrained, leading to a substantial increase in the cost of Li-ion batteries. In this connection, new rechargeable battery systems such as sodium ion, sodium metal, magnesium, metal-air, and metal-sulfur batteries are being considered as alternatives to replace Li-ion batteries. In particular, Na-ion batteries have attracted rapidly increasing attention owing to the low cost of Na-ion batteries.1-3

Because of their low cost, the main potential application of Na-ion batteries is considered to be large-scale energy storage systems. However, it should be stressed that it is not easy to reduce the cost of Na-ion batteries relative to that of Li-ion batteries, in spite of the inexpensive Na precursors. The current Na-ion batteries have slightly lower energy densities than Li-ion batteries. This implies that the cost per energy ($/Wh) of Na-ion batteries cannot be easily reduced because the energy density limitations offset the cost savings due to the use of Na. Therefore, it is necessary to develop high capacity electrode materials to improve the energy density of Na-ion batteries.

In this presentation, we will focus on our recent works involving the development of high capacity layered-structured sodium transition metal oxide cathode materials to improve the energy density of Na-ion batteries. We have examined various layered Na1-xMO2 (M = Mn, Fe, Ni, and their solid solution analogues) materials, along with understanding the role of dopants in the reaction mechanisms of those electrode materials. We also discuss the failure mechanisms of those cathode materials and suggest a strategy for improving electrochemical performance.

[1] Y. Kim, K.-H. Ha, S. M. Oh, K. T. Lee, Chem. Eur. J., 20 (2014) 11980.

[2] S. Y. Hong, Y. Kim, Y. Park, A. Choi, N.-S. Choi, K. T. Lee, Energy Environ. Sci., 6, (2013) 2067.

[3] M.-S. Kwon, S. G. Lim, Y. Park, S.-M. Lee, K. Y. Chung, T. J. Shin, K. T. Lee, ACS Appl. Mater. Interfaces, 9 (2017) 14758.
Fabrication of a Novel, Multidimensional, 2.5D All-Solid-State Lithium-Ion Battery
Authors: Ashby David , Choi Christopher S , Edwards Martin A. , Talin Albert Alec , White Henry S. , Dunn Bruce S.
Published: May 2020

The limitations of current microbattery designs is best highlighted by the restricted electrochemical performance of planar cells stemming from their long diffusion path lengths, or by the fabrication and material constraints of recent, novel 3D-electrode architectures. Herein, the fabrication and properties of a multidimensional, high areal-capacity, 2.5D battery are described as means to address the limitations of planar and 3D-electrode designs. Our 2.5D battery, composed of a 3D LiFePO4 array and a planar Li anode, provides a way to achieve high energy densities, while utilization of a high ionic conductivity, solution-processed ionogel electrolyte enables high power densities (4.1 mWh cm-2 at 2.8 mW cm-2). This 2.5D design exhibits improved or comparable energy and power densities to the best 3D batteries in literature, while simplifying the fabrication process, eliminating the liquid electrolyte, and facilitating an easily customizable battery. The exemplary performance and simple fabrication process of the 2.5D design, possible because of the ionogel electrolyte, presents a promising direction for the integration of energy-storage devices into on-chip and microelectronic applications that is impractical with current high-performance 3D-battery designs.

Figure 1
(Invited) Characterization and Design of Solid Polymer-Based High Voltage Lithium Batteries
Authors: Yang Yuan
Published: May 2020

Solid state batteries are attractive for next-generation energy storage due to their excellent safety and potentially high energy density. In this talk I will present recent progress on characterizing and designing polymer-based solid state batteries. In characterizations, an emerging stimulated Raman scattering microscopy is developed to visualize ion transport in electrolyte and electrode-electrolyte interactions. Such studies unveil the strong mechano-chemical coupling at the Li metal/electrolyte interface which shows depletion-induced suppression of lithium dendrite growth. In material designs, surface modification is developed to stabilize 4V cathode with PEO-based polymer electrolytes and achieve long term cycling, such as 85% capacity retention over 200 cycles. Both LiCoO2 and NCM523 cathodes are investigated. Characterizations show that surface modification preserve the crystallinity of cathode surface, which is the major reason for enhanced stability.
Designs of Experiments to Optimize Li-Ion Batteries
Authors: Rynne Olivier , Dubarry Matthieu , Lepage David , Molson Corentin , Nicolas Eva , Ayme-Perrot David , Rochefort Dominic , Dollé Mickael
Published: May 2020

Studies pinpointed the limitation of power-related performance for Li-ion batteries to the microstructure of each electrode.1, 2 This random arrangement of the active material (AM) and carbon filling particles bound by a polymer is typically characterized through physical values such as tortuosity, porosity and Mac Mullin Number.3 There is nonetheless no consensus on what the best formulation is for a given set of electrode components.

The relationship between microstructure and performance is investigated by planning and analyzing a Design of Experiments based on a Complex Mixture Design. Thirty different formulations were characterized where Li4Ti5O12 was the AM, and carbon black and carbon nanofibers were conductive fillers. As for the binder, two were studied: polyvinylidene fluoride and a fluorine-free thermoplastic elastomer.4 All other factors, e.g. rheology or experimenter bias, were closely monitored and finely controlled to remain identical for all samples.

Electrochemical performance were studied at low, medium and high charging speeds to account for different limitations of full capacity retention. Statistical analysis showed clear correlations between the formulation and the electrodes’ capacity with very high descriptive statistics, e.g. R2. Lastly, strong correlations were found between capacity and microstructure, strengthening further the trust in the empirical equations. These robust models helped choosing optimal fluorine-free formulations that surpassed even the highest performing previous electrodes.

1. Vasileiadis, A.; Klerk, N. J. J. d.; Smith, R. B.; Ganapathy, S.; Harks, P. P. R. M. L.; Bazant, M. Z.; Wagemaker, M., Toward Optimal Performance and In‐Depth Understanding of Spinel Li4Ti5O12 Electrodes through Phase Field Modeling. Advanced Functional Materials
2018,
0 (0), 1705992.

2. Ngandjong, A. C.; Rucci, A.; Maiza, M.; Shukla, G.; Vazquez-Arenas, J.; Franco, A. A., Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process with Performance at the Cell Level. The Journal of Physical Chemistry Letters
2017,
8 (23), 5966-5972.

3. Landesfeind, J.; Hattendorff, J.; Ehrl, A.; Wall, W. A.; Gasteiger, H. A., Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy. Journal of The Electrochemical Society
2016,
163 (7), A1373-A1387.

4. Rynne, O.; Lepage, D.; Aymé-Perrot, D.; Rochefort, D.; Dollé, M., Application of a Commercially-Available Fluorine-Free Thermoplastic Elastomer as a Binder for High-Power Li-Ion Battery Electrodes. Journal of The Electrochemical Society
2019,
166 (6), A1140-A1146.

With this presentation, we want to show the versatility and power of Designs of Experiments to the community, whether for electrode formulation or new material synthesis, as the input parameters can be easily interchangeable.

Figure 1
(Invited) Correlating Electrolyte Structure with Interphasial Chemistry of Lithium Metal Anode
Authors: Hu Enyuan , Shadike Zulipiya , Lee Hongkyung , Cao Xia , Xiao Jie , Yang Xiao-Qing
Published: May 2020

Properties of the solid-electrolyte interphase (SEI) strongly effects the morphology, features and overall performance of the Lithium metal anode (LMA). It is well accepted but least understood that the formation mechanism of SEI is correlated with the electrolyte solvation structure. Here, synchrotron X-ray diffraction (XRD), pair distribution function (PDF) analysis, and molecular dynamic (MD) simulation are employed to obtain direct insight to the correlation between electrolyte solvation structure and interphasial chemistry. Systems of lithium bis(fluorosulfonyl)imide in propylene carbonate, dimethyl carbonate, and dimethoxyethane at both low (1M) and high (5 M) salt concentrations are studied. While solvents dominate in the solvation structure for low concentration electrolytes (LCE), a large number of anions enter the solvation shell in high concentration electrolytes (HCE). Quantification of crystalline phases in the bulk SEI reveal that while dendrites are the dominant phases for SEI of LCE, their formation is significantly suppressed in SEI of HCE. Highly nano-sized LiF, Li2O, and LiOH are dominant crystalline phases in SEI of HCE. The SEI of HCE is also very rich in oligomers resulting from anion decomposition. The small crystallites and amorphous oligomers promise fast Li ion conduction in the SEI and therefore a superior electrochemical performance of LMA.
(Invited) Morphological and Chemical Stability Issues at Interfaces in Solid State Batteries
Authors: Ceder Gerbrand
Published: May 2020

Interfacial issues are believed to be a key issue challenging the long-time operation of solid-state batteries. In particular on the anode side, where the use of metallic lithium will be a requirement to achieve high energy density, understanding plating morphology and the ability for lithium to penetrate and grow into hard solid electrolytes has been challenging. Using modeling that integrates electrolyte transport with the mechanical behavior of the electrolyte and metallic lithium we show that the ability of lithium to grow through a solid conductor depends on just a few intrinsic materials parameters, which can be used to design more dendrite resistant electrolytes. We also delineate the particular conditions under which electronic conductivity can lead to lithium deposition in the conductor.

On the cathode side the lack of high voltage stability of solid electrolytes and coating materials is the main driver for impedance growth. Using basic chemical principles, similar to those used to make high voltage cathodes, one can design coating materials that remain intact even for high voltage charging. We belief that the development of more quantitative guidelines for interfacial stability is important for advancing the solid-state battery field.
Anion Charge Dependent Lithium Ion Diffusion in Solids
Authors: Xu Zhenming , Zhu Hong
Published: May 2020

Utilizing solid-state electrolyte materials for lithium-ion batteries not only fundamentally solve the safety problem of the commercial lithium-ion batteries, but also greatly increase the energy density of batteries. Lithium solid-state electrolyte materials should have high conductivities at room temperature comparable to liquid electrolyte, good (electro)chemical stabilities, mechanical properties, and excellent compatibilities with electrodes. The proposed design principles for lithium superionic conductors mainly include the concepts of bcc anion framework, low lithium phonon density center, and high distortion lithium-anion polyhedron. Moreover, the smaller anionic charge is well considered to benefit for the rapid transport of lithium ion, e.g. negative monovalent anions are more favorable for cation diffusion than negative divalent anions.

However, our recent studies of the chalcopyrite-structured sulfides and non-spinel-structured halides show that the lithium-ion migration energy barrier can be effectively reduced by comprehensively regulating the anion charge and lithium-ion coordination environments. For example, for lithium ion diffusion between two adjacent lithium-anion octahedrons through a tetrahedral transition state, the greater the anionic charge is, the lower the lithium ion diffusion energy barrier will be. While for lithium ion diffusion between two adjacent lithium-anion tetrahedrons through an octahedral transition state, the smaller the anion charge is, the lower the lithium ion diffusion barrier will be. According to this design principle and choosing the appropriate cations to isolate the electronic conductive channels, we obtained the quaternary Li2CuPS4 solid electrolyte material with tetrahedral lithium occupations. Li2CuPS4 not only has high thermodynamic stability, but also theoretically possess the high ionic conductivity of 84.9 mS/cm at room temperature. In addition, the non-spinel halide Li3LaI6 with octahedral lithium occupations has relatively high ionic conductivity of 1.23 mS/cm at room temperature, and its thermodynamic stability and electrochemical stability are far superior to sulfides. This new understanding of comprehensively regulating the anion charge and lithium-ion coordination environments to enhance lithium ion transport can be applied for the design and optimization of new superionic conductors.
Origin of Intergranular Li Metal Propagation in Garnet-Based Solid Electrolyte By Direct Electronic Structure Analysis and Performance Improvement By Bandgap Engineering
Authors: Kim Jusik , Heo Sung , Kim Hyunseok , Kim Sewon , Im Dongmin , Park SeongYoung , Badding Michael , Song Zhen , Chang Jaemyung
Published: May 2020

Garnet-structured oxide electrolyte (Li7La3Zr2O12, LLZO) has the significant advantage of being chemically and electrochemically stable against Li metal, which allows the implementation of Li metal batteries. However, a short-circuit failure by Li penetration through the LLZO electrolyte has remained a crucial issue for safety and is a major hurdle for Li-based batteries to overcome. Here, we investigate the mechanism of Li dendrite formation for the crystalline Ta-doped LLZO (LLZTO) by examining their energy band structures and defect states using reflection electron energy loss spectroscopy (REELS), scanning photoelectron microscopy (SPEM), and nanoscale charge-based deep level transient spectroscopy (Nano Q-DLTS) techniques. The experimental results reveal that the Schottky barrier height (SBH) was lowered by 0.5 eV due to the defect states localized in grain boundaries and the metallic Li propagation along the grain boundaries is caused by the SBH reduction. Based on the analytical results, the laser annealing of LLZTO was performed as a bandgap engineering method to suppress the Li dendrite formation by forming a mixed surface layer of amorphous LLZTO and Li2O, which has a wide bandgap to block the electron injection into the grain boundaries. The electrochemical measurements for the laser treated LLZTO demonstrate that the stability and cycling performance are significantly improved. This study sheds light on the importance of electronic structure, in particular, defect states to develop high performance oxide solid electrolytes for Li metal batteries and the practicality of surface modification by laser treatment.
The Development of High-Throughput Methods in the Study of Solid State Li-Electrolytes
Authors: Jonderian Antranik , McCalla Eric
Published: May 2020

High-throughput experimentation is a fast and efficient methodology for materials discovery, screening, and optimization. It has, therefore, garnered a lot of attention from battery researchers as a potential way to accelerate the development of next-generation Li-ion batteries and battery systems beyond Li-ion. However, its successful use in battery materials discovery has been extremely limited due to a variety of challenges including: (i) difficulties in synthesizing mg-scale samples that are comparable to bulk samples made by industrial methods, (ii) limited high-throughput characterization acting like a bottleneck even after high throughput synthesis is developed, and (iii) high cost of commercially available high-throughput instrumentation. Here, we develop high throughput techniques for solid-state electrolytes.

First, a novel synthesis approach is used to make 64 mg-scale solid electrolytes simultaneously. The powder samples are prepared by a citrate sol-gel method using an automated dispensing system. These powders were formulated into sixty-four pellets using a home-made high-throughput pellet press die. The samples are then sintered at high temperature to yield the solid electrolytes. The proof of concept here is performed on the Li-La-Ti-O pseudo-ternary system that includes the perovskites Li3xLa2/3-xTiO3, considered candidates for solid-state electrolytes for high energy lithium-ion batteries. Given that vacancies and other defects play an essential role in ionic conductivity, the screening of complete phase diagrams has the potential to reveal phases with optimized defect contents and thus yield improved solid electrolytes.

We have therefore developed a high-throughput characterization suite for solid electrolytes. First, we use a high throughput X-ray diffractometer capable of producing Rietveld quality patterns for mg-scale samples in 10 min such that 64 patterns can be obtained in under 12 h. This system is readily used to produce structural phase diagrams in ternary or even quaternary systems. Next, a high throughput electrochemical impedance spectrometer is used to map the ionic conductivities onto the phase diagrams. Finally, high throughput electrochemistry is used to determine the stability window of the electrolytes. All aspects of this workflow are demonstrated on the Li-La-Ti-O system. This now permits the synthesis and full characterization of approximately 192 compositions per week with one researcher only. This approach is well suited to determine the structure-property relations in complex composition spaces.

The complete ternary Li-La-Ti phase diagram synthesized at 1150 °C with slow cooling was determined and will be presented in detail. The total (ionic + electronic) conductivity of the phase diagram was mapped by the electrochemical impedance spectroscopy. Quenching was performed to verify that transformations during slow cooling are moderate in this system. Consequences for the development of other solid electrolytes will also be discussed.
Improving Ionic Conduction in Solid State Batteries Via Bulk and Interface Structure Design
Authors: Liu Zhantao , Chen Hailong
Published: May 2020

All-solid-state Li-ion batteries feature higher energy density, wider operation temperature range and better safety properties1 than conventional Li-ion batteries. The search for high performance solid state ionic conductors as the solid electrolyte (SEs) is one of the focuses of the battery field. Design principles for SE have been raised based on computational or experimental explorations. In this work, we will present our material design practices focusing on two factors that we believe to be essential for the performance of SE in solid state batteries: carrier density and interface. Attempts of tuning the carrier and vacancy densities were implemented in selected model systems, including known material systems and new material families, such as Li15P4S16Cl3
2 and other thiophosphates. Drastic improvement on ionic conductivity at room temperature was realized by either increasing the vacancy density or increasing stabilized interstitial sites. Interface design and engineering were also attempted with model systems including oxides, sulfides and halides. The impact of interface on effective conductivity was investigated with electrochemical impedance spectroscopy and complementary crystal structural characterizations including synchrotron X-ray diffraction and pair distribution function analysis. Modeling of interface structure was also employed to further understand the ionic conduction in the solid electrolyte layer and composite electrodes.

1. Auvergniot, J.; Cassel, A.; Ledeuil, J.-B.; Viallet, V.; Seznec, V.; Dedryvère, R., Interface Stability of Argyrodite Li6PS5Cl toward LiCoO2, LiNi1/3Co1/3Mn1/3O2, and LiMn2O4 in Bulk All-Solid-State Batteries. Chemistry of Materials
2017,
29 (9), 3883-3890.

2. Liu, ZT.; Zinkevich, T.; He, XF.; Indris, S.; Xiong, S.; Liu, J.; Xu, W.; Bai, J.; Mo, Yifei; Chen, HL., Li15P4S16Cl3, a new lithium chloro-thiophosphate as a solid state ionic conductor. Inorganic Chemistry, in press.
(Invited) Recent Progress on Development of High-Energy Density Li Metal Batteries at INL
Authors: Li Bin
Published: May 2020

The increasing demand for energy has facilitated the development of Li metal batteries due to its lowest redox potential and the high theoretical specific capacity as the anode. However, the formation of dendritic or mossy Li during Li plating hampered the development of Li metal batteries. In order to meet US DOE energy and cost targets, Li metal-based batteries with sulfur or high-Ni LiNixMnyCozO2 (NMC) as cathodes as well as lean electrolytes are strongly recommended. Their cycling performances should be largely enhanced. Additionally, similar to commercially available traditional Li ion batteries, failure diagnosis technologies of Li metal batteries have to be explored along the improvement of battery chemistry for the industry acceptance. In this presentation, we will talk about the recent progress on the development of high-energy density Li metal batteries at Idaho National Lab (INL), which includes (1) the pressure effect on the cycling performances of Li-NMC pouch cells; (2) the rational design of sulfur electrodes under lean electrolyte conditions; (3) An approach to distinguish battery failure mechanisms and thus fast predict the lifetime of Li-NMC batteries.
New Salts for Lithium-Ion Cells - Low Fluorine and Nonfluorine Electrolytes for Higher Safety
Authors: Niedzicki Leszek , Kasprzyk Marta , Trzeciak Tomasz , Wieczorek Wladyslaw
Published: May 2020

For the last 30 years, Li-ion cells have become the primary choice as power source for all electronic devices, mobile electronics and electric vehicles of all sorts. During this time huge advance took place in electrode active materials, separators and engineering of electrodes. However, lithium salt used in commercially available Li-ion cells (LiPF6) is still the same. It is known for its thermal instability, chemical incompatibility with silicon-based electrodes and reactions with even traces of water resulting in large costs of anhydrous solvents as well as need for desiccation systems of whole factories. Apart from known issues, it is also a reason for enormous fluorine content in Li-ion cells. Salt itself contains as high as 75% of fluorine in its mass. Thus, electrolytes contain ca. 10% of pure fluorine (typical 1 mol/kg concentration). As whole world makes an effort to drop toxic components, prevent formation of toxic wastes, it is also needed to drop use of fluorine in consumer products, including batteries.

Previously, we presented LiTDI salt, which is now on the market, that contains only ca. 30% of fluorine in its mass and can be used at lower concentrations, decreasing fluorine content in the electrolyte to below 1.5-3% (depending on the application and electrolyte composition).

Here we present first non-fluorine salts that successfully work in Li-ion cells environment. This way electrolyte fluorine content can reach 0% for the first time in Li-ion cell technology history. We show that getting rid of fluorine from the electrolyte does not necessarily means that good performance of both electrolyte and a cell is not possible. Ionic conductivity (over 8 mS/cm), and even more important, lithium cation conductivity values (σLi+ over 3 mS/cm) are comparable to those of LiPF6 and LiTDI, while not giving up on stability properties. Both thermal (up to at least 270°C) and electrochemical (at least up to 4.3 V vs Li) stabilities are still at the satisfactory level. It is still possible to use new salts with all active electrode materials available on the market as well as new ones that currently are not possible to use due to their incompatibility with fluorine-containing salts.

In this presentation we will show newest results of development and investigation of novel anions including low-fluorine-content and nonfluorine ones as main electrolytes in Li-ion cells.
Creation, Evolution, and Characterization of SEI in Li-Metal Batteries Using Ab Initio Techniques
Authors: Seminario Jorge M.
Published: May 2020

We report our recent findings in the study of the creation, evolution, characterization and simulation of solid electrolyte interphases (SEI) using first principles theoretical-computational techniques. Our simulations are performed on a nanobattery model that allow us to study the charge of a battery under the effect of an external electric field. Our analyses include both, liquid and solid-state, electrolytes under the presence and effects of realistic anodes and cathodes. A large variety of details will be presented, including speciation at interfaces, conductivities, energetics, phase formation, among others.
(Invited) All Solid-State Batteries: Synthesis, Interfacial Engineering and Recycling
Authors: Meng Ying Shirley
Published: May 2020

All-solid-state batteries (ASSBs) have attracted enormous attention over recent years because they have many advantages over their liquid counterparts such as the enhanced safety, absence of electrolyte leakage, and improved energy density by enabling the use of metallic anodes. However, the performance of ASSBs is still hard to meet the requirements for commercialization. Many challenges have remained in order to improve the interfacial properties, increase the cycling life and energy density. Herein, we demonstrate the progression to build practical ASSBs by using sulfide-based superionic conductors as electrolytes since they have high ionic conductivities, facile synthesis procedures, and favorable mechanical properties. We show that each step is critical to achieving high-performance ASSBs, from synthesis optimization, interfacial engineering to scalable fabrication. Particularly, we succeeded to construct a stable interface between the electrolyte Li6PS5Cl (LPSCl) and the cathode LiNi0.85Co0.1Al0.05O2 (NCA). We will also show how to make lithium metal a feasible anode for all solid state battery through the knowledge we obtained from advanced diagnosis of lithium metal anode.
(Invited) Formation of Solid/Solid Interface for All Solid State Batteries
Authors: Chen Zonghai
Published: May 2020

All solid-state battery is pursued with the expectation to substantially improve the safety and potentially volumetric energy density of lithium batteries. A good solid state electrolyte to serve this purpose requires a high Li+ conductivity and stable interfaces for both lithium anode and oxide cathode to maintain an efficient Li+ conducting network for normal operation of all solid state batteries. To format and maintain an effective cathode electrolyte interface is one of the crucial barriers for the development of all solid state batteries. This difficulty can be mitigated by adding a small amount of liquid or polymer electrolytes between the cathode and the solid-state electrolyte, decomposing a solid/solid interface into two solid/liquid or solid/polymer interfaces. In this work, the difficulty in forming a stable solid/solid interface is investigated using various synchrotron probes. Without losing the generality, Li7La3Zr2O12(LLZO)/LiNi0.6Mn0.2Co0.2O2(NMC) was selected as the model system to investigate the technical difficulty of forming an effective interface.
Electrochemical Formation of Li Metal Anodes to Enable Li-Free Manufacturing of Solid-State Batteries
Authors: Wang Michael , Sakamoto Jeff
Published: May 2020

Solid-state batteries could not only present a safer alternative to conventional Li-ion batteries, but also the possibility for drastic increases in energy density. Replacing flammable liquid electrolytes with a non-flammable solid electrolyte could improve safety and using metallic Li instead of state-of-the-art graphite would double the energy density. While solid electrolytes could enable advanced cathode chemistries, currently it is believed that state-of-the-art cathodes (e.g. NMC, NCA, spinel, olivine) are the most viable to achieve >1000Wh L-1, high cycle life, and cost targets. However, given that state-of-the-art cathodes are fully lithiated, any pre-deposited Li will add extraneous volume, negating the energy density benefits of the Li metal. Furthermore, due to the difficulty and cost of handling free-standing Li foils, incorporating metallic Li anodes with representative thicknesses, low interfacial resistance, and using scalable processes remains a major manufacturing challenge. In lithium phosphorus oxynitride (LiPON) solid-state systems, “Li-free” configurations have been feasibly demonstrated, where the Li metal anode is formed in operando upon charging, using the Li contained within the cathode. However, with bulk-processed electrolytes like the garnet Li7La3Zr2O12 (LLZO), in operando formation has not been feasibly demonstrated. This work evaluates the potential for “Li-free” battery manufacturing using LLZO electrolytes. It is demonstrated that Li metal anodes with thicknesses >20μm (>5mAh cm-2) can be formed in operando without any evidence of Li filament propagation, as characterized using electrochemical and materials characterization methods. Furthermore, the mechanics of Li electrodeposition at the solid-solid current-collector/electrolyte interface are investigated. Finally, the preliminary cycling performance of in operando formed Li anodes is evaluated. The results not only provide insight into the mechanisms of electrodeposition at solid-solid interfaces, but also demonstrates the feasibility of “Li-free” manufacturing of Li metal solid-state batteries.
A Simple One-Dimensional Transport Model to Explain Inverse Signatures in Lithium-Metal Batteries
Authors: Uppaluri Maitri , Subramaniam Akshay , Subramanian Venkat R.
Published: May 2020

Lithium metal is being investigated as the negative electrode for lithium batteries due to its high theoretical capacity (3,860 mAh g–1) and negative electrochemical potential (-3.040 V vs standard hydrogen electrode) 1. However, using lithium metal poses several challenges, including dendritic electrodeposition and accumulation of dead lithium. These phenomena can cause the cell to short, and also contribute to poor cyclability 2.

To prevent these issues, it is important to understand the transport of lithium ions and the kinetics that contribute to lithium deposition and stripping on the anode. Lithium deposition and stripping is correlated with unique voltage signatures, based on the morphology 3. Physics-based continuum models can be used to understand lithium ion transport effects on deposition and stripping, and on the emergent voltage signatures.

Our past work studied one-dimensional models for lithium symmetric cells to model charge transport and capture the transitions in voltage observed experimentally 4. In this work, we propose a simple diffusion-based model based on our past work that shows inverse signatures of lithium ion concentration and overpotential for the lithium deposition reaction. We show that using a transport model alone can produce unique inverse voltage signatures. The model used is a one-dimensional moving boundary model, where the deposition and stripping of lithium is modeled as a moving interface.

The cell was simulated at different current densities, and for different variations in diffusivities of the anion and cation in the electrolyte. The current density affects both interface motion and ion transport in the electrolyte. The interplay between these two phenomena then determines characteristic signatures of overpotential and concentration, and ultimately the cell voltage.

References

1. W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, and J. G. Zhang, Energy Environ. Sci., 7, 513–537 (2014).

2. D. Lin, Y. Liu, and Y. Cui, Nat. Nanotechnol., 12, 194–206 (2017).

3. K. N. Wood, M. Noked, and N. P. Dasgupta, ACS Energy Lett., 2, 664–672 (2017).

4. A. Subramaniam, J. Chen, T. Jang, R. M. Kasse, M. F. Toney, and N. R. Geise, J. Electrochem. Soc., 166, A3806–A3819 (2019).
Sulfide-Based All-Solid-State Batteries: From Electrolyte Synthesis to Interface Design
Authors: Zhao Feipeng , Liang Jianwen , Sun Xueliang
Published: May 2020

All-solid-state Li-metal batteries (ASSLMBs) have attracted increasing attentions because of their high specific energy density and advantage of safety compared with conventional liquid electrolyte-based Li-ion batteries (LIBs). Solid-state electrolytes (SSEs) are the key component for ASSLMBs. Sulfide-based SSEs exhibit a very competitive ionic conductivity compared with oxides, polymer-based, and other kinds of SSEs. However, the poor electrode/sulfide SSEs interface and the moisture-sensitivity hinder the development.1

From the point of sulfide SSEs synthesis, we demonstrate that using fluorine (F) incorporation in an Argyrodite Li6PS5Cl sulfide electrolyte (LPSCl) can achieve an ultra-stable Li metal/sulfide SSEs interface. The performance can be comparable to that in the symmetric cells based on liquid electrolytes. The condensed interfacial structure and high fluorinated chemical composition of the in-situ formed interface lead to the high performance.2 In addition, Sn (IV) is employed to partially replace problematic P (V) in Argyrodite sulfide Li6PS5I (LPSI) SSEs to prepare relatively air-stable sulfide SSEs, which is attributed to the strong Sn-S bonding energy in the Sn-substituted LPSI electrolytes (LPSI-Sn). Benefiting from the aliovalent element substitution and I-based chemistry, LPSI-Sn electrolyte can show 125-times increase in the ionic conductivity and significantly improved Li metal compatibility.3

For the interface design, we focus on the improvement of the Li anode/sulfide SSEs interface stability. Inorganic LixSiSy and Li3PS4 protection layer achieved by in-situ growing on the Li metal, which can serve as an effective interlayer to improve chemical/electrochemical stability of Li/sulfide SSEs interface.4-5 The growth of Li dendrites at the interface is suppressed. The side reaction between Li metal anodes and sulfide SSEs is also well controlled.In addition, the Li-ion conductive interlayer has demonstrated favorable ionic conductivity fundamentally. High-rate ASSLMBs can be achieved by using these inorganic Li-ion conductive protection layers.

Re
ferences

1. Q. Zhang, et al. Sulfide-Based Solid-State Electrolytes: Synthesis, Stability, and Potential for All-Solid-State Batteries. Advanced Materials 2019, 31, 1901131.

2. F. Zhao, X. Sun, et al. Ultra-Stable Li Anode Interface Achieved by Incorporating Fluorine in Argyrodite Sulfide Electrolytes. Submitted.

3. F. Zhao, J. Liang, X. Sun, et al. A Versatile Sn-Substituted Argyrodite Sulfide Electrolyte for All-Solid-State Li Metal Batteries. Submitted.

4. J. Liang, X. Li, X. Sun, et al. An Air-Stable and Dendrite-Free Li Anode for Highly Stable All-Solid-State Sulfide-Based Li Batteries. Advanced Energy Materials 2019, 9, 1902125.

5. J. Liang, X. Li, X. Sun, et al. In Situ Li3PS4 Solid-State Electrolyte Protection Layers for Superior Long-Life and High-Rate Lithium-Metal Anodes. Advanced Materials 2018, 30, 1804684.
Assembling an All-Solid-State Ceramic Battery: Assessment of Chemical and Thermal Compatibility of Solid Ceramic Electrolytes and Active Material Using High Temperature X-Ray Diffraction
Authors: Bertrand Marc , Rousselot Steeve , Ayme-Perrot David , Dollé Mickael
Published: May 2020

Lithium ion batteries (LIBs) are the most known and used batteries for portable energy storage because of their high energy densities, long cycle life and relatively low price. However, they still fall short for the development of long range electric vehicles and stationary applications due to organic liquid electrolytes that are currently electrochemically limited and present safety issues (fire or explosion in case of short-cut or overcharging). Solid oxide electrolytes appear to be one of the solutions because of their non-flammability and wide potential window. Inorganic oxide electrolytes have reasonable ionic conductivities (10-5-10-3 S/cm at ambient temperature), high mechanical strength, and high chemical stability.

Assembling an all ceramic solid-state battery with inorganic oxide electrolyte is challenging as it requires a deep knowledge of the thermal, chemical and electrochemical behavior of each component of the cell. The battery must be a continuous monolithic block with a thin dense electrolyte separator, in order to minimize the polarization. In addition, optimized interfaces between active material and electrolytes must be ensured in the composite electrodes. This is often achieved with oxide-based materials by using high temperature processing.

Thermal expansion occurring during this step can lead to cracks, which will affect the performance and cyclability of the device. The primary driving force of a crack during the fabrication of hybrid ceramic is the stress due to mismatch in the coefficient of thermal expansion (TEC) of the various layers/materials. Moreover, it must be certain that no reaction occurs between active material and electrolytes in the sintering temperature range. These are then two key parameters to address for the development of all ceramic solid-state batteries.

In this work, in situ-XRD has been used to determine the TEC and the thermal stability of various well-known oxide active materials and solid electrolytes. The aim of this presentation is to discuss about the best selection of compatible oxide-based materials to avoid unwanted cracks or reaction during the sintering processing of ceramic solid-state batteries.
(Invited) Fabrication and Characterization of High Power Ga2O3 Based Diodes
Authors: Ren Fan , Xian Minghan , Fares Chaker , Carey Patrick H , Haque Aman , Tadjer Marko J , Pearton Stephen J.
Published: May 2020

A review will be given of the device processing needs for Ga2O3 power rectifiers. The main devices employed in power converters and wireless charging systems will be vertical rectifiers and MOSFETs. This talk will focus on the issues for rectifier fabrication and characterization. The rectifiers involve thick epitaxial layers on conducting substrates and require stable Schottky contacts, edge termination methods to reduce electric field crowding, dry etch patterning in the case of trench structures, and low resistance Ohmic contacts in which ion implantation or low bandgap interfacial oxides are used to minimize the specific contact resistance. In addition, stable insulators for field plates with acceptable band offsets relative to the Ga2O3 to ensure adequate electrical field redistribution, and enhancement rectifier breakdown voltage will be discussed. Success in these areas would lead to rectifiers with better on-state performance and a much improved range of functionality for power switching characterizations.
(Invited) Defect and Impurity Characterization in Wide Bandgap Materials and Interfaces: Impact on Thermal Transport
Authors: Goorsky Mark S. , Graham Samuel , Hopkins Patrick , Henry Asegun , Luo Tengfei , Doolittle W. Alan , Khan Asif
Published: May 2020

Wide bandgap materials are suitable for high power and high temperature applications. However, these materials must also transport heat from the active device regions effectively. Structural defects, chemical defects, and interface properties can degrade performance. Electron microscopy and x-ray scattering based techniques are employed to provide insight into the defects present in these materials. When these techniques are integrated with thermal transport measurements and theoretical insights gained from molecular dynamics simulations, a much better understanding of thermal transport in wide bandgap materials can be realized. Examples of how defects impact transport for diamond boundary interfaces, AlN layers, and GaN heterostructures will be presented.