bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards Dry and Contaminant Free Ca(BF4)2 Based Electrolyte for Ca Metal Anode Based Batteries
Authors: Forero-Saboya Juan , Ponrouch Alexandre
Published: May 2020

Divalent metal batteries have gained much attention recently given the high gravimetric capacities of calcium and magnesium metal electrodes (1340 and 2000 mAh/g respectively), and thus, holding promise as high energy density next-generation battery technologies. Although calcium metal possesses lower reduction potential (-2.76 V vs SHE) than magnesium (-2.38 V vs SHE), the development of calcium metal batteries has been hampered by the lack of electrolytes allowing for reversible electrodeposition. After the first demonstration of reversible calcium plating/stripping in and organic electrolyte based on Ca(BF4)2 in carbonate solvents [1], the attention devoted to calcium-based batteries have substantially increased. Recently, other electrolyte systems allowing for reversible plating/stripping were reported [2–4].

One of the crucial parameters to consider in the devolvement of divalent metal batteries is the presence of undesired impurities, particularly water, as it will affect greatly the surface chemistry of the calcium metal anode and prevent electrodeposition. As normally alkaline-earth metal salts are more hygroscopic that their alkaline counterparts, obtaining ultra-dry electrolytes is a key challenge which needs to be addressed. In the case of commercial Ca(BF4)2, most likely synthesised in aqueous solution, the water content is usually as high as 30wt%.

In the present study we evaluate different drying methods and report on their effect on the stability of the BF4
- anion. The performance of the differently dried electrolytes with regard to the calcium electrodeposition is evaluated and discussed. An anhydrous synthetic route of Ca(BF4)2 will also be presented and compared to the commercially available salt.

References

1. A. Ponrouch, C. Frontera, F. Bardé, and M. R. Palacín, Nat. Mater., 15, 169–172 (2016).

2. D. Wang et al., Nat. Mater., 17, 16–20 (2017).

3. Z. Li, O. Fuhr, M. Fichtner, and Z. Zhao-Karger, Energy Environ. Sci. (2019).

4. A. Shyamsunder, L. E. Blanc, A. Assoud, and L. F. Nazar, ACS Energy Lett., 4, 2271–2276 (2019).
(Invited) Mitigating Layer Collapse at High Voltages
Authors: Liu Hao , Fan Qinglu
Published: May 2020

Layered lithium first-row transition metal oxide is widely used as cathode materials in lithium-ion batteries and promises a high theoretical capacity. However, only 70% of its theoretical capacity is utilized in practice due to irreversible changes in the structure as well as the microstructure of the electrode when cycled to high voltages. Previous studies have identified intergranular cracking as a dominant cause of the long-term capacity fading induced by the anisotropic volume change upon lithium de-intercalation. Such anisotropic volume change can be mitigated by preventing the layer collapse at high voltages. One approach to such an effect is through cation substitution. This work presents a structure-function relationship study to evaluate the efficacy of such an approach.
Predicting the Open Circuit Potential Curve for a Class of Ni-Rich Cathode Materials
Authors: Kimura Kevin Wayne , Wilhelm Rebecca , Kim Soo , Besli Muenir Mustafa , Usubelli Camille , Ziegler Joerg , Klein Reinhardt , Christensen Jake , Gorlin Yelena
Published: May 2020

Ni-rich cathodes are a class of materials for lithium-ion batteries (LIBs), which are currently gaining popularity in applications requiring high energy density, such as electric vehicles (EVs). Successful integration of these materials into EVs necessitates a fundamental understanding of their electrochemical properties, including the open circuit potential (OCP) curve. This study investigates the relationship between Ni stoichiometry and the OCP curve of two cathode families: Ni-rich NCAs and Ni-rich NCMs with a constant Mn content of 20%. First, it demonstrates how to predict the OCP curves of the materials within these two cathode families. Then, it applies the same methodology to determine the Ni content in a Ni-rich NCA cathode with an unknown chemical formula with similar accuracy as the inductively coupled plasma (ICP) technique. Our results suggest that the presented methodology can be further extended to additional cathode families and aid both in the prediction of their OCP curves and in validating the stoichiometry of newly synthesized materials.
Directing Chemistry at Electrodes Using Precisely-Defined Electrochemical Interfaces
Authors: Prabhakaran Venkateshkumar , Johnson Grant , Assary Rajeev , Hankins Kie , Engelhard Mark H , Shutthanandan Vaithiyalingam , Martinez Abraham , Thevuthasan Suntharampillai , Murugesan Vijayakumar , Mueller Karl T
Published: May 2020

Molecular-level understanding of chemistry occurring at electrode-electrolyte interfaces (EEIs) during charge transfer processes as a function of electric field strength and concentration gradient is necessary to enable the rational design of more efficient electrochemical technologies for energy storage. The scientific challenge is to unravel convoluted interfacial interactions (i.e., adsorption, coordination, transport) and control the reaction pathways that lead to formation of desired products over unwanted byproducts. Ultimately the objective is to modulate the evolution of the solid-electrolyte interphase (SEI) in batteries for enhanced performance and durability. Soft landing of mass-selected ions, a versatile approach to surface modification, is ideally suited to preparation of well-defined interfaces with predetermined electrochemically active ions. The “atom-by-atom” precision of ion soft landing enables experiments that unravel the complexity associated with the multitude of interfacial processes occurring simultaneously at electrified interfaces. We present evidence for a substantial advancement in understanding such complex interfacial reactions on Mg battery electrodes employing user-defined layer-by-layer assembly of electrochemically active cations and solvated counter-ions with precisely-selected stoichiometry and concentration. As an example, ion soft landing combined with operando infrared reflection-absorption spectroscopy (IRRAS) and in-situ x-ray photoelectron spectroscopy (XPS) was used to characterize the decomposition of counter electrolyte anions and solvent molecules on Mg electrodes. Furthermore, we explored using an aliovalent doped metal (e.g., Al) on the Mg surface to control the decomposition and stabilize the SEI layer formation as a function of both concentration and potential. Our in-situ multimodal analysis enabled the capture of spectroscopic signatures from key chemical transformations of electrolyte anions and solvent molecules on reactive metal surfaces. These experimental results were correlated with the evolution of the SEI layer as predicted by theory to provide molecular-level insight into the reaction mechanism. In summary, our unique approach allowed us to acquire more delineated understanding of electrochemical transformations across length scales in operating EEIs and aids in the rational design of improved sustainable electrochemical energy technologies.
(Invited) Intercalation Anodes Based on Titanium Oxides for Sodium-Ion Batteriesmmd
Authors: Doeff Marca M , Alvarado Judith
Published: May 2020

Possible supply security issues associated with lithium-ion batteries have recently prompted further research into sodium-ion analogs, which can be used as drop-in replacements. Sodium ion batteries have reached a fairly advanced level of development and are probably the closest of all the “Beyond Lithium Ion” systems to commercialization. At present, hard carbons are the most commonly used anode materials for sodium-ion batteries, but these materials have some drawbacks, such as potential safety issues due to the very low insertion potentials. While several alloy systems such as Na/Sn or Na/P have been suggested as alternatives, the large volume changes are difficult to manage and have a negative impact on energy density. We have recently described several types of intercalation anodes based on sodium titanates with low potentials and high capacities. These materials are denser than carbon and have smaller volume changes than the alloys. One of these is “sodium nonatitanate” (NaTi3O6(OH)·2H2O), a stepped layered structure made hydrothermally and dried to remove interlayer water. Capacities are somewhat dependent upon drying temperature, with a maximum close to 200 mAh/g achieved for the material treated at 500°C. These anodes show excellent reversibility, which may be a consequence of their structure, which appears to have some tunnel-like features. Lepidocrocite-type (corrugated structure) titanates are another attractive group of materials with similar electrochemical properties, including good reversibility and high capacities. These materials will be discussed in more detail for this presentation.
CrPO4-Type of Compounds As Anode Materials for Na-Ion Batteries
Authors: Yahia Hamdi Ben
Published: May 2020

To date, research on sodium-ion batteries started to gain more interest. It is mainly motivated by the large abundance of sodium and the hope to produce batteries that are cheaper compared to LIBs and less prone to resource issues and safety concerns [1-3].

During the last three years, our research team has developed several electroactive materials for sodium-ion batteries. Among them, the NASICON- NaFe2-xMx(PO4)(SO4)2 (M=Fe, V, Cr and 0 ≤ x ≤ 1) and the alluaudite- Na2
M
1Fe2(PO4)3 (M=Mn, Fe, Co, Ni) type of compounds. We also discovered recently several compounds crystallizing with the α-CrPO4-type of structure. These phases are very interesting since they contain several vacancies and therefore enable the intercalation of up to three sodium atoms which leads to capacities above 160 mAh/g with very stable cycling at 1C rate. In this paper, we report on the structural and electrochemical properties of the six new M-doped-VPO4 phases (M= Mn, Fe, Co, Ni, Zn, Mg). The crystal structures were solved by the Rietveld method using powder X-ray diffraction (PXRD) data. The electrochemical performances were examined by galvanometric cycling and cyclic voltammetry. The stability of the structure during cycling was followed by ex-situ PXRD experiments.

The cycling performance of the Zn-doped-VPO4 phase is given in Figure 1. Cells embedding (NaPF6:EC:PC) electrolyte and Na-metal were used. Additional details on the other five new phases will be provided during the conference.

Figure 1. Electrochemical performance of the newly prepared Zinc-doped-VPO4 phase at the rate of 1C vs. Na+/Na and the general intercalation mechanism for the α-CrPO4-type of structure.

Reference:

[1] Makino, K.; Katayama, Y.; Miura, T.; Kishi, T., J. Power Sources 2002, 112, 85−89.

[2] Gaubicher, J.; Wurm, C.; Goward, G.; Masquelier, C., Nazar, L., Chem. Mater. 2000, 12, 3240−3242.

[3] Jian, Z.; Zhao, L.; Pan, H.; Hu, Y.-S.; Li, H.; Chen, W., Chen, L., Electrochem. Commun. 2012, 14, 86−89.

Figure 1
Ceramic-Doped in Cross-Linked Solid Polymer Electrolyte for Solid-State Batteries
Authors: Meda Lamartine , Pandey Gaind P. , Williams Jere A. , Lebean Arielle , Abiade Asha Ain , Wu James J.
Published: May 2020

Replacing liquid electrolytes with solid-state Li-ion conductors is one way to achieve safe rechargeable batteries with high energy density. Semi-interpenetrating polymer network (s-IPN) was synthesized from the mixture of poly(propylene carbonate), poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) diacrylate (PEGDA), and lithium bis(trifluoromethane)sulfonamide salt via one-pot thermal curing method. The crosslinker PEGDA content and salt concentration were optimized and the best result was abtained at a molar ratio of EO:Li ∼ 14:1. The electrolyte with higher salt concentration had lower ionic conductivity, consistent with higher glass transition temperature of poly(ethylene glycol) chain. Differential scanning calorimetry has shown a low degree of crystallinity when lithium lanthanum zirconate doped tantalum (LLZTO) was added to the s- IPN electrolyte which corresponds to an increase in ionic conductivity, 4.5 x 10-4 S/cm at 40°C. The resulting composite polymer electrolyte (CPE) showed high electrochemical stability up to 5.5 V. Lithium plating and stripping at 0.1 mA/cm2 at room temperature revealed a stable Li/electrolyte interface and no dendrite formation. Cycling performance of a full solid-state cell made with the CPE using LiFePO4 as the cathode will be discussed.

Figure 1
Effects of Charging Protocols on Dendrite Growth
Authors: Ryan Emily , Cannon Andrew , Tan Jinwang
Published: May 2020

The constant current constant voltage charging protocol has been the standard for battery charging because of its simplicity and ease of implementation. However, with the continued integration of batteries into more complex electronics, i.e. electric vehicles, and medical devices, customizing charging schemes based on the particular need has become more appealing. This is especially true when fast charging is necessary. A major challenge in adopting alternative charging protocols is dendritic growth along the anode surface. The dendrites cause safety and efficiency issues. To mitigate the dendritic growth, a variety of specialized charging protocols, i.e. pulse and boost, have been proposed. Through computational modeling, a direct investigation can be conducted to determine which of the parameters for charging must be balanced in order to rapidly charge the battery and suppress dendrite growth. These parameters include the magnitude of the pulsed charge as well as the frequency. Direct observations of dendritic growth can be used to inform which charging protocols will lead to high performance and longer cycle life.
Investigation of the Garnet Solid Electrolyte and Lithium Metal Anode Interface
Authors: Brown Zachary Lee , Pasta Mauro
Published: May 2020

Improving the energy density of lithium-ion batteries by replacing a graphite anode with lithium metal anode is heavily desired.1 The garnet (LLZO) solid electrolytes are promising candidates to protect lithium metal due to their high lithium-ion conductivity and high elastic modulus, however, the interfacial chemistry between LLZO/Li is poorly understood.2-4 In this work, LLZO electrolytes of >98% theoretical density were prepared with Field Assisted Sintering Technology. The solid state electrochemistry of LLZO with lithium and blocking electrodes is characterized using electrochemical impedance spectroscopy. Further, investigation of interfacial phenomena between LLZO and Li metal using a suite of surface characterization techniques will be discussed in detail.

References

1. Liu J., Bao Z., Cui Y., Dufek E. J., Goodenough J. B., Khalifah P., Li Q., Liaw B. Y., Liu P., Manthiram A., Meng Y. S., Subramanian V. R., Toney M. F., Viswanathan V. V., Whittingham M. S., Xiao J., Xu W., Yang J., Yang X. Q., and Zhang J. G., Energy, 4, 180 (2019).

2. Krauskopf, Hartmann H., Zeier W. G., and Janek J. ACS Appl. Mater. Interfaces, 11, 14463 (2019).

3. Fu K., GongY., LiuB., ZhuY., Xu S., YaoY., Luo W., Wang C., Lacey S. D., DaiJ., ChenY., MoY., WachsmanE., and Hu L. Sci. Advances, 3, e1601659 (2017).

4. Sharafi A., KazyakE., DavisA. L., YuS., Thompson T., SiegelD. J., DasguptaN. P., and Sakamoto J. Chem. Mater.,
29, 7961 (2017).
Defects in Pervoskite Ceramics for Enhanced Ionic Conductivity and Chemical Interaction
Authors: Yang Hui , Wu Nianqiang
Published: May 2020

Oxygen vacancies have been created in pervoskite Li3x
La2/3 − x
TiO3 (LLTO) materials. The presence of oxygen vacancies decrease the activation energy for lithium ion hopping in the crystalline structure and increase the ionic conductivity of the LLTO material. Strong chemical interaction occurs between the nanofibers and the polymer matrix in the composite solid-state electrolytes based on three-dimensional (3D) hydrogen treated LLTO. The composite electrolyte exhibited a high ionic conductivity at room temperature, and large electrochemical stability window of up to 5.0 V vs. Li/Li. Full cells assembled with the composite electrolyte exhibited good rate capacity and cycling performance.
Engineering Interfaces for Stable Na Metal Solid-State Batteries
Authors: Hatzell Kelsey , Ren Yuxun
Published: May 2020

Efficient and reversible cycling of alkali metal anodes is a key requirement for achieving high-energy density solid-state batteries [1,2]. While there has been significant interest and research on understanding plating and stripping mechanisms of lithium metal, there has been far less work to understand sodium metal electrode kinetics at solid electrolyte interfaces. Sodium metal is highly reactive with most solid electrolytes which leads to the formation of unstable interphases. These interphases lead to low cycle life and poor power performance. Herein, we study the electrochemical and transport properties of a novel hybrid polymer-Na3SbS4 solid electrolyte. Combining a polymer with a inorganic solid electrolytes provides a way to process thin sodium-ion conducting solid electrolytes at scale and provides a pathway toward tailoring the stability of the solid electrolyte against a alkali metal [3]. A cross-linking approached is utilized to control the structure of the inorganic ionic conductor within the polymer matrix and improve the electrolyte stability. The buried interface is characterized using a suite of in situ imaging techniques to track transformations at the Na-metal interface.

[1]Shen, Fengyu, Marm B. Dixit, Xianghui Xiao, and Kelsey B. Hatzell. "Effect of pore connectivity on Li dendrite propagation within LLZO electrolytes observed with synchrotron X-ray tomography." ACS Energy Letters 3, no. 4 (2018): 1056-1061.

[2]Zaman, Wahid, Nicholas M. Hortance, Marm B. Dixit, Vincent De Andrande, and Kelsey Bridget Hatzell. "Visualizing percolation and ion transport in hybrid solid electrolytes for Li-metal batteries." Journal of Materials Chemistry A (2019).

[3]Dixit, Marm B., Wahid Zaman, Yousuf Bootwala, Yanjie Zheng, Marta C. Hatzell, and Kelsey B. Hatzell. "Scalable manufacturing of hybrid solid electrolytes with interface control." ACS applied materials & interfaces (2019).
Non-Destructive, Non-Invasive Noise Measurements for Metallic Lithium Anodes for Lithium Ion Batteries
Authors: Karaoglu Gozde , Uzundal Can Berk , Ulgut Burak
Published: May 2020

Electrochemical Noise measurements have been in the spotlight of electrochemical analysis for measurements on stochastic modes of corrosion since the days of Dawson (Hladky and Dawson Corrosion Science 21(4), (1981),317-322). More recently, electrochemical noise measurements for fuel cells and batteries came up as non-invasive and non-perturbing testing methods that can be used for research(Journal of The Electrochemical Society, 165 (11) A2557-A2562 (2018)) and a potential real-time monitoring tool (Denisov et.al. Fuel Cells 17,(2017),225-237).

Metallic lithium anodes are currently commercially employed for non-rechargeable batteries (e.g LiSOCl2 or LiMnO2). The main hurdle along the way of implementation in rechargeable batteries is the dendrite formation during the charging process (Cheng, et.al. Chem. Rev. 2017, 117, 10403−10473). The formation of dendrites during charging can lead to catastrophic failure of the batteries including thermal runaway. Though studies on avoiding such failures through either modifying the surface of the electrode and/or the kinetics of deposition are underway, however, as indicated by the review: “more smartly designed in situ or operando techniques are urgently needed to track the process in a working cell”.

We have been working on battery noise measurements for the past number of years (Turkish Journal of Chemistry, 42, (2018), 859-868). We have recently shown that the noise of primary Li/MnO2 batteries increase to measurable levels upon suffering a short circuit (Journal of the Electrochemical Society 165(11),(2018),A2557-A2562) and that this is due to the uneven discharge of the metallic lithium anode(Journal of the Electrochemical Society, submitted).

In this contribution, we are going to be reporting electrochemical noise as a truly operando method to study dendrite formation. As the measurement requires no modification to the cell (i.e. no windows in the case or the current collectors, no geometry change, not a half cell) and no perturbation in the applied current or the voltage, it is the ultimate non-invasive and non-perturbing method that has the potential to be used as not only a research tool, but also a real-time implementable sensor that can be commercially deployed.

As shown in the figure below, using a metallic lithium anode, the noise after a charging attempt with a high current does show an increased noise level due to the uneven formation of dendrites.

Figure 1
(Invited) All Solid-State Batteries: From Interface to New-Type Electrolytes
Authors: Sun Andy Xueliang
Published: May 2020

All-state-state lithium batteries (ASSLBs) have gained worldwide attention because of the high ionic conductivity of SEs, intrinsic safety and improved energy density. In ASSLBs, solid-state electrolyte is a key component. Compared with polymer-based and oxide-based electrolytes, sulfide-based electrolyte generally exhibits the highest ionic conductivity (10-3 ~ 10-2 S/cm) and favorable mechanical property. However, the serious interfacial challenge, bad air stability, narrow electrochemical windows of sulfide-based electrolyte significantly impede development of sulfide-based ASSLBs. Generally, an artificial, uniform and ultrathin interfacial layer is critical to address these challenges. Atomic layer deposition (ALD) and molecular layer deposition (MLD) are unique coating techniques that can realize excellent coverage and conformal deposition with precisely controllable at the nanoscale level due to its self-limiting nature, which are ideal for addressing the challenges of interface in SSLBs.

In this talk, I will demonstrate to apply ALD/MLD to
(i)

stabilize the interface between cathode electrodes and electrolytes and prevent the formation of intrinsically high resistance layers,
(ii)

suppress elemental inter-diffusion during the operation of SSLBs,
(iii)

fabricate facile ionic transportation channels to facilitate ion exchange between different components of SSLBs, and

(iv)

buffer volume changes during cycling of SSLBs [1]
.

In this talk, I will talk about halide-based electrolyte for ASSLBs. Compared with sulfide-based electrolyte, both experimental and theoretical results recently demonstrate that halide-based electrolytes have more advantages including high RT ionic conductivity (>10-3 S cm-1, theoretically possible 10-2 S cm-1), wide electrochemically stable window (possible up to 6 V), high air-stability, good stability toward oxide cathode materials, and even salable water synthesis strategy [2-3].

References:

1. Zhao, X. Sun .Addressing Interfacial Issues in Liquid-based and Solid-State Batteries by Atomic and Molecular Layer Deposition. Joule. 2, 2583-2604(2018).

2. Li, J. Liang, X. Sun, et al., H2O-Mediated Synthesis of Superionic Halide Solid Electrolyte. Angewandte Chemie International Edition, 2019, http://dx.doi.org/10.1002/anie.201909805.

3. Li, J. Liang, X. Sun, et al.,. Air-Stable Li3InCl6 Electrolyte with High Voltage Compatibility for All-Solid-State Batteries. Energy Environ. Sci.,2019, 12, 2665 - 267.
The Production of Carbon Fibers from the Centrifugal Spinning of Aqueous Polymer Solutions for Use As Binder-Free Anodes in Lithium-Ion Batteries
Authors: Alcoutlabi Mataz , Orrostieta Chavez Roberto
Published: May 2020

We present results of centrifugally spun carbon fibers (CFs) made from aqueous Polyvinylpyrrolidone (PVP) solution. In the production of these fibers, the centrifugal spinning technique was used due to its high production rate of fibers. Subsequent heat treatment was conducted using a novel three step process that resulted in reduced residual stresses in the fibers after the centrifugal spinning process and subsequent thermal treatment. Moreover, this process increases the fibers’ resistance to degradation during carbonization at higher temperatures. Electrochemical performance tests were conducted on Li-ion half cells using the CFs as binder-free anodes. The carbon-fiber anode delivered a discharge capacity of Capacities of 618.7, 222.7 and 214.5 mAh g-1 at the 1st, 50th, and 100th cycles at a current density of 100 mAg-1. This work provides a novel and feasible pathway for designing and developing carbon fibers from water soluble polymer solution for use as anodes in high-performance lithium ion and sodium-ion batteries.
Comparison of Different Macroscopic Models for the Simulation of Li-S Batteries with Liquid Electrolyte
Authors: Tan Kenley , Shen Chao , Zheng Jim P. , Andrei Petru
Published: May 2020

Despite the large amount of experimental research that currently exists on Li-S batteries, the theoretical understanding of the physio-chemical processes at the macroscopic scale is lacking behind. The very few macroscopic models that currently exist in the literature are often contradictory and provide a partial and often inaccurate description of the experimental data. This fact is due in part to our lack of understanding of complex chemical and electrochemical reactions in these batteries, to challenges related to properly model nucleation and precipitation effects, and to difficulties related to parameter identification and solving the macroscopic equation numerically in more than one spatial dimension. In this presentation we will discuss about each of the above challenges, separately. Then, we will compare the different models that currently exist in the literature for the macroscopic description of Li-S batteries with liquid electrolyte and will discuss about their limitations, areas of applicability, and performance. Special attention will be given to the way the different models describe the nucleation and precipitation effects during charging and discharging.
Carbon Composite Nanofibers Produced By Hybrid-Spinning of Polyacrylonitrile Precursor As Anodes for Lithium Ion Batteries
Authors: Huitron Juan , Alcoutlabi Mataz
Published: May 2020

In this study, polyacrylonitrile (PAN) nanofibers are produced through a novel technique known as Hybrid-Spinning (HS) and used as a precursor for anodes in lithium ion batteries (LIBs). HS is a combination of two fiber-producing technologies: Centrifugal spinning (CS) and Electrospinning (ES). The use of HS for nanofiber production is promising due the limitations of both CS and ES. CS produces a high yield of nanofibers through centrifugal forces but is unable to account for the control of the fiber morphology, which limits the potential of the nanofibers-production through this technology. ES, on the other hand, produces nanofibers through electrical forces, allowing for a high degree of fiber morphology control by alternating the electrical field and process parameters. However, the high cost, safety concerns, and low yield of ES makes it unsuitable for the mass production of nanofibers in industry. Therefore, Hybrid Spinning has a high potential in changing the nanofiber industry by removing the limitations of both ES and FS while also minimizing safety-concerns, cost, and environmental impact. This work documents the morphology and characteristics of PAN nanofibers produced through HS and compares them to nanofibers made through FS and ES. The PAN fibrous mats obtained by HS are then converted into carbon nanofibers by calcination and directly used as free-binder anodes in lithium-ion batteries. The electrochemical performance of the HS carbon-fiber anodes is then compared with that prepared by ES and CS to determine the viability of HS technology with respect to Lithium-ion battery applications.
Designing a Li-Metal Battery to Surviving in Practical Operating Condition for Electric Vehicle Applications
Authors: PARK Seongjin , Sun Yang-Kook
Published: May 2020

We propose a new breakthrough in realizing a practical Li-metal battery capable of fast charging while delivering a high energy density. To stabilize the Li metal anode, the electrolyte, consisting of 1M LiPF6 and 0.05M lithium difluoro(oxalate)borate (LiDFOB) dissolved in the mixture of ethyl methyl carbonate (EMC) and fluoroethylene carbonate (FEC) solution, ensures a stable robust solid electrolyte interphase (SEI) layer on the anode surface. LiNO3 pretreatment of the Li-metal anode adds a prior Li2O-rich SEI layer that provides the mechanical strength to maintain the SEI layer from breakdown against to dendritic Li growth at extremely high charge current density. Meanwhile, Al-doped full-concentration-gradient Li[Ni0.75Co0.10Mn0.15]O2 cathode provides the necessary cycling stability at a high cathode loading level. Integrating these components produced a LMB that allowed a high areal capacity of 4.1 mAh cm-2 and accomplished an unprecedented cycling stability over 300 cycles at a high current density of 3.6 mA cm-2. In addition, proposed LMB can further extended when moderate capacity loading of 2.0 mAh cm-2 under ultra-fast charging-discharging conditions; specifically, the LMB showed excellent long-term cycling stability up to 500 cycles under charge at 3.6 mA cm-2 (30 min) but discharge with 9 mA cm-2 (12 min). We believe that our findings presented herein provide new perspectives for the development of practical LMBs that satisfy the capacity and charging rate requirements for future electric vehicles.

Reference

1. J.-Y. Hwang, S.-J. Park, C. S. Yoon and Y.-K. Sun, Energy Environ. Sci., 2019, 12, 2174.

2. S.-J. Park, J.-Y. Hwang, C. S. Yoon, H.-G. Jung and Y.-K. Sun, ACS Appl. Mater. Interfaces, 2018, 10, 17985.

3. Y.-K. Sun, Z. Chen, H.-J. Noh, D.-J. Lee, H.-G. Jung, Y. Ren, S. Wang, C. S. Yoon, S.-T. Myung and K. Amine, Nat. Mater., 2012, 11, 942.
Phase Transformation of High Capacity LiCoPO4 during Galvanostatic Cycling
Authors: Zhu Wen
Published: May 2020

In situ X-ray diffraction has been employed to study the crystal structure changes of doped LiCoPO4 during a galvanostatic charge/discharge process at a slow rate of C/30. The results revealed that upon the lithium extraction from doped LiCoPO4, an intermediate phase of LixCoPO4 is observed before the formation of completely delithiated phase CoPO4. The phase transformation is reversible and follows solid solution and two phase reaction routes at different stages of the delithiation.
Development of Cu-Based Positive Electrode for an All-Solid-State Fluoride Shuttle Battery
Authors: Tanaka Akihisa , Sakurai Katsutoshi , Morita Yoshiyuki , Nakanishi Koji , Kiuchi Hisao , Ogumi Zempachi , Abe Takeshi
Published: May 2020

For the development of batteries with higher energy density, we have been developing all-solid-state fluoride shuttle batteries (FSBs) in RISING2 project of NEDO, Japan. Here we report the reversible electrochemical fluorination/de-fluorination of copper-based positive electrode using operando XAFS (X-ray absorption fine structure) measurement during charge/discharge processes. The Operando XAFS measurements were performed at the BL28XU of SPring-8, Japan. Based on the XAFS results, we have tried to improve the utilization of the active material by devising the electrode manufacturing method.

The CeF3/Ce0.95Ba0.05F2.95/Cu cell showed 680 mAh/g(Cu) charge capacity and 593 mAh/g(Cu) discharge capacity, which was higher capacity than that of the previous works [1,2]. During the charge process, the operando XAFS spectra showed that pre-edge and white line peak intensity decreased and increased in proportion to the charge capacity, respectively, indicating that Cu converts to CuF2. On the other hand, the changes of XAFS spectra were opposite during the discharge process. These results indicate that this positive electrode is highly reversible for fluorination/de-fluorination reaction of Cu. However, some Cu metal remained at the full charge state because the charge capacity didn’t reach to the theoretical specific capacity (843 mAh/g), which was also confirmed from the XAFS spectrum.

Other details will be shown in the conference.

Acknowledgments

This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan under the Research and Development Initiative for Scientific Innovation of New Generation Battery (RISING2) project.

References

[1] M. A. Reddy et al., J. Mater. Chem.
21, 17059 (2011).

[2] Duc Tho Thieu et al., Adv. Funct. Mater.
27, 1701051 (2017)
Influence of Electrode Density and Porosity on the Performance of NCA Positive Electrode for 18650 Li-Ion Batteries
Authors: Sarawutanukul Sangchai , Tomon Chanikarn , Phattharasupakun Nutthaphon , Sawangphruk Montree
Published: May 2020

Calendaring process is one of the most important steps in the line production of 18650 lithium ion battery. The process does not only densify the electrode but also promote the adhesion of active materials onto the metal current collector. However, the resultant increase in tortuosity of the primary ion transport pore networks imposes a severe tradeoff between the electrode thickness and the rate capability. This work aims to investigate the impact of electrode density and porosity on the cell performance. First, the effect of pressure applied during the calendaring process of LiNi0.8Co0.15Al0.05O2 (NCA) electrode was investigated. The pressure used was varied from 400 kg cm2 to 2000 kg cm2, and the quality of the pressed electrode was measured in terms of particle packing, porosity, and density. As these factors directly affect the diffusion of Li-ion in the active material and their depletion in the electrolyte phase, they greatly influence the energy density and power density of the cell. It was found that the electrode quality is improved with the increasing pressure applied during the calendering process. However, applying an overpressuing force could lead to an increase in tortuosity and over-packing of the electrode, which can reduce the electrode capacity at relative high C-rates. The optimum electrochemical performance of 18650 NCA battery with the capacity of c.a. 2.9 Ah was achieved by applying an optimumpressure to obtain an electrode with 3.7 g cm-3 NCA density. The improvement of the energy-power relationship observed here demonstrates the optimization of cell parameters according to the principle of cell engineering.
Improved High-Voltage Cycling Stability of Nano-Thin TiO2 Layer Coated Ni-Rich Layered Oxides By Polydopamine Pre-Treatment
Authors: Kim Hyeongwoo , Jang Jihye , Byun Dongjin , Kim Hyungseok , Choi Wonchang
Published: May 2020

Demand for electric vehicles or large-scale energy storage system boost the development of high-energy and stable lithium-ion batteries (LIBs) and the utilization of cathode materials having higher capacity has been a key issue to enhance the energy density of current LIBs. Accordingly, a large attention has been paid to Ni-rich layered oxides which potentially achieve a higher specific capacity than LiCoO2, and many researches have shown that Ni-rich layered oxides are promising candidate cathode materials with high capacity over 220 mAh/g. Increasing the Ni content help to obtain high capacity, however, structural instability of Ni-rich layered oxides results in serious degradation of the cycling stability. Generally, this problem is mainly related to the surface degradation which can be ascribed to side-reaction products and NiO formation from the generation of highly reactive Ni4+ ions during charging to high-voltage (≥ 4.3 V). This surface degradation is accelerated when the cell is operated at high temperature (>60 oC) because side reactions at the electrode/electrolyte interface and structural degradation are seriously worsen at elevated temperature. To solve this problem, coating strategy has been an effective way to mitigate the surface degradation, and the uniformity of the coating layer is critical to suppress the side reaction at an interface between particles and electrolyte. However, conventional coating methods such as ball-milling or wet coating have a limitation to obtain the uniform coating layer due to the lack of the driving force for even distribution of coating materials on the surface of the electrode material.

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, we decorated the polydopamine (PDA) on the NCM particles surface to trap Ti4+ ions through forming O-H catechol groups. This helps to attract Ti(OEt)4 molecules in the coating solution to the NCM surface, thus uniform TiO2 nanolayer can be obtained after the calcination process. We confirmed that the uniformly coated TiO2 nanolayer helps to suppress side reactions and improve the surface stability. Consequently, it enhances the cycling stability in the high-voltage operation (4.5 V), and improves the high temperature (60 oC) cycling performance. The presented results are a further step toward a wise design of stable Ni-rich based cathodes for high energy density LIBs.

Figure 1
(Invited) Structure, Chemistry, and Charge Transfer Resistance of the Interface between Garnet Solid Electrolyte and Oxide Cathodes
Authors: Yildiz Bilge , Kim Younggyu , Jung Jiwon , Rahman Anisur
Published: May 2020

All-solid-state batteries promise significant safety and energy density advantages over liquid-electrolyte batteries. The interface between the cathode and the solid electrolyte is an important contributor to charge transfer resistance. Strong bonding of solid oxide electrolytes and cathodes requires sintering at elevated temperatures. Knowledge of the temperature dependence of the composition and charge transfer properties of this interface is important for determining the ideal sintering conditions. To understand the interfacial decomposition processes and their onset temperatures, model cathode systems of LiCoO2 (LCO) and LiNi0.6Mn0.2Co0.2O2 (NMC622) thin films deposited on cubic Al-doped Li7La3Zr2O12 (LLZO) pellets were studied as a function of temperature, gas composition and electrochemical conditions. The methods combine interface-sensitive techniques, including X-ray photoelectron spectroscopy (XPS), synchrotron X-ray absorption spectroscopy, hard X-ray photoemission (HAXPES), and synchrotron X-ray diffraction. In this talk, we will present the found precipitation products at the interface as a function of synthesis and electrochemical conditions, their role in altering the interface resistance to Li transfer, and compare the LCO and NMC related cathodes in terms of their instability onset conditions. Results in particular indicate the importance of the selected temperature and gas conditions in giving rise to more stable interfaces, with fast Li transfer between the garnet electrolyte and the oxide cathodes.
Drifts (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) - a Way to Assess the Reactivity of Solid Electrolytes with Ambient Air
Authors: Sedlmeier Christian , Lanzinger Maria , Gasteiger Hubert A.
Published: May 2020

All-Solid-State-Batteries (ASSBs) are envisioned to be the next-generation lithium-ion batteries (LIBs). Replacing the inflammable organic electrolyte in conventional liquid electrolyte LIBs by a non-inflammable inorganic solid electrolyte (SE) is one of the concepts to increase battery safety. Moreover, ASSBs may offer higher gravimetric and volumetric energy density compared to liquid electrolyte based technology.[1,2] However, their high reactivity with ambient air is a major obstacle which prevents ASSBs from industrial scale processing, as production under inert atmosphere is not possible on this level.[3] Thus, industrial ASSB production would have to take place in dry-rooms, leading to the question whether SE handling in dry-room atmospheres containing O2 and CO2 and ppm-levels of moisture is possible.

Therefore, we will examine the reactivity of the commercially available solid electrolyte Li10SnP2S12 (LSPS) with O2 and CO2 as well as with the typical H2O concentration in ambient air, followed by reactivity studies with a mixture of CO2 and H2O vapor. For this purpose, we used Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS), a highly surface sensitive infrared technique.The hermetically sealed DRIFTS cell containing the SE powder was set up such that it could be purged with dry or humidified streams of inert gas (Ar), O2, and CO2, or mixtures thereof while monitoring in situ the chemical changes of the LSPS solid electrolyte and the formed gaseous species by DRIFTS. Figure 1 shows stacked IR spectra of LSPS after exposure to different gasses, stating no reactivity with O2 or CO2 but noticeable changes in the IR spectrum for exposure to moisture and a combination of CO2 and moisture, respectively, indicating decomposition reactions.The spectral analysis of the decomposition process is supported by ex situ X-Ray Diffractometry (XRD) analysis of the LSPS powder after exposure to the different gas streams. Concluding, the impact of exposing LSPS to the above mentioned gas mixtures on the ionic conductivity of the solid electrolyte will be demonstrated.

Acknowledgements:

This work was carried out as part of the research project ASSB coordinated by ZAE Bayern. The project is funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy.

References:

[1] Janek, J. and Zeier, W. G. A solid future for battery development. Nat. Energy
1, 1–4 (2016).

[2] Kamaya, N., Homma, K., Yamakawa, Y., Hirayama, M., Kanno, R., Yonemura, Y., Kamiyama, T., Kato, Y., Hama, S., Kawamoto, K. and Mitsui, A. A lithium superionic conductor. Nat.
Mater.
10, 682–686 (2011).

[3] Muramatsu, H., Hayashi, A., Ohtoma, T., Hama, S. and Tatsumisago, M. Structural change of Li2S – P2S5 sulfide solid electrolytes in the atmosphere. Solid State Ionics
182, 116–119 (2011).

Figure 1
Evaluation of a Manufacturable in-Situ Thin Film RTD Temperature Sensor for Lithium-Ion Batteries
Authors: Riemer Douglas P. , Davis Michael W
Published: May 2020

As an in-situ temperature sensor for Li-Ion batteries, RTD’s (Resistance Temperature Detector) have a simple linear response to temperature and can accurately sense from -40 °C through thermal runaway initiation. An economical manufacturing method using a high-volume real-to-real flexible substrate is used that can combine the tab and sensors or produce sensor packages where either type integrate into a pouch cell in a similar way to the electrode tabs.

Commercial 4.84 Ahr Li-ion NMC/graphite pouch cells were constructed incorporating a prototype thin film Nickel based RTD integrated tab at the center of the jelly-roll. This unified approach greatly simplifies the methods of construction avoiding the effects of around 2%1 strain due to the charge/discharge cycle. Much of the capital cost associated with adding new components to the manufacturing of Li-ion batteries are also avoided. Owing to the method of construction, the RTD has little to no impact on battery energy density which is very important to the competitive landscape.

Experimental in-operando results illustrating the importance of sensor location are presented such as the case shown in Figure 1. More utilitarian and more extreme cases are also investigated comparing the in-situ vs ex-situ temperature responses to situations such as external short-circuit as well as normal operation modes. Progress on long term cycling will also be presented showing stability of sensor and any effects on battery performance.

Incorporation of additional sensors are also discussed such as reference electrodes. In a recent review2 cathode materials such as LiFePO4 make a more suitable long term pseudo-reference electrode material than the much more difficult to handle Li metal alloys. A sensor package of the type described here allows for simple addition of a pseudo-reference electrode utilizing cathode material.

1 Drew Joseph Pereira et al. Meet. Abstr. 2019;MA2019-02:428

2 Rinaldo Raccichini et al. Batteries 2019, 5, 12

Figure 1
Elucidating the Interfacial Reactions for Conversion-Alloying Materials Towards the Realization of High-Performance Lithium-Ion Full-Cells
Authors: Asenbauer Jakob , Eisenmann Tobias , Hoefling Alexander , Kuenzel Matthias , Tübke Jens , Passerini Stefano , Bresser Dominic
Published: May 2020

The unique combination of high energy and power density made Li-ion batteries the state-of-the-art electrochemical energy storage technology for powering small consumer electronics as well as large-scale applications like electric vehicles (EVs).[1] This increasing diversity of potential applications, however, also results in a greater variety of required characteristics. For the use in EVs, in fact, two of the major issues of the current lithium-ion chemistry based on graphite anodes are the sluggish lithium transport across the solid electrolyte interphase (SEI) upon lithium intercalation into the graphite host structure and the very low lithiation potential – in combination intrinsically limiting the fast charging capability.[2] This intrinsic kinetic limitation triggered researchers to find alternative anodes, following, for instance, an alloying (e.g., Si) or a (multi-phase) conversion (e.g., Fe2O3) mechanism. Both alternatives commonly show higher capacities and frequently superior rate capabilities. Despite steady improvements, though, these alternatives still suffer from capacity fading due to extensive volume variations (especially alloying materials) and low energy efficiencies due to a significant voltage hysteresis (in particular for conversion materials) as well as an improvable coulombic efficiency. Conversion/alloying-materials (CAMs) are a rather new class of electrode compounds that combine the alloying and conversion mechanism in one single material.[3] Upon lithiation, nanograins of the non-alloying element are formed in situ and build a percolating electron conductive network. Besides allowing for the reversible formation of the simultaneously formed Li2O matrix, this metallic nano-network enables fast lithiation and delithiation kinetics, rendering CAMs a promising candidate for high-power applications. Nevertheless, there is still a lack of knowledge which parameters eventually determine the overall performance and cycling stability.

Herein, we show that the reactions occurring at the electrode/electrolyte interface play a decisive role and that these reactions are largely dependent on the (surface) chemistry of the active material. The techniques used include amongst others ex situ synchrotron soft X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and in situ isothermal microcalorimetry. It is shown that the stabilization of the interface is essential when targeting long-term stable performance – in both half-cells and full-cells. The latter provides a specific energy of 284 Wh kg-1 accompanied by an excellent energy efficiency of >93%.

[1] N. Nitta, F. Wu, J. T. Lee, G. Yushin, Mater. Today
2015, 18, 252–264.

[2] N. Loeffler, D. Bresser, S. Passerini, Johnson Matthey Technol. Rev.
2015, 59, 34–44.

[3] D. Bresser, S. Passerini, B. Scrosati, Energy Environ. Sci.
2016, 9, 3348–3367.