bluuebunny/crossref_metadata_2025 huggingface dataset:
Plan-View Operando Video Microscopy of Li Metal Anodes
Authors: Sanchez Adrian J. , Chen Yuxin , Kazyak Eric , Chen Kuan-Hung , Pattison Ethan , Dasgupta Neil P.
Published: February 2020

The reversible cycling of Li metal anodes is severely limited by poor cycle life and safety concerns. Dendrite growth has been linked to the poor performance of Li metal, but a comprehensive understanding of the mechanistic origins and dynamic evolution of Li metal morphology during electrodeposition and stripping is missing. Herein, a multifunctional operando visualization platform that synchronizes optical recordings with cycling electrochemistry is used to study nucleation on Li metal and dendrite reversibility. This platform was initially used to understand the origins of the “peaking” behavior exhibited in the voltage traces of Li symmetric cells [1-3]. However, by limiting the viewing angle to a cross-sectional perspective, the impact of electrode surface variations, including microstructure, flaws, and chemical inhomogeneities cannot be fully accounted for. To address this, a plan-view optical visualization cell was designed that maintains a highly uniform current distribution along the electrode surface. The top-down view provided by the updated cell is better suited to provide quantitative measurements of nucleation on Li metal and identify links between nucleation and microstructure.

Utilizing this new cell, we are able to: 1) Quantitatively identify the spatial distribution of “hot spots” for both nucleation of both dendrites and pits; 2) Detail how these hot spots evolve during cycling; 3) Quantify dendrite and pit areal nucleation density as a function of current density; 4) Provide an understanding of why surface uniformity increases after the first cycle; 5) Elucidate the substantial impact that pits have on Li metal cycling; 6) Explore the dependency between dendrite size and reversibility; and 7) Explore the mechanisms that lead to the formation of dead Li. The knowledge from this study can be used to inform rational design of Li metal surface treatments and architectures to improve the reversibility and cycle life.

1. K. N. Wood, E. Kazyak, A. F. Chadwick, K. H. Chen, J. G. Zhang, K. Thornton, N. P. Dasgupta, ACS Cent. Sci.
2, 790 (2016)

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

3. K.-H. Chen, K. N. Wood, E. Kazyak, W. S. LePage, A. L. Davis, A. J. Sanchez, N. P. Dasgupta, J. Mater. Chem. A
5, 11671 (2017)
(Invited) Solid-Electrolyte Interphase on Li Metal Surfaces
Authors: Balbuena Perla B.
Published: February 2020

Novel advances in experiments and computations are providing fresh insights into the yet unsolved puzzle of obtaining smooth Li plating and stripping events in Li-metal batteries. And the “always blamed” solid-electrolyte interphase (SEI) layer remains the center of the controversy. In this talk, we will discuss the role of the electrolyte structure and concentration, including high concentrated and localized high-concentrated electrolytes among others. We will focus on the role of each type of SEI layer (LiF, Li2CO3, Li2O, LiOH) on the cation deposition and stripping events. The possibility of artificial coatings will be investigated. The analysis is based on our first principles computations and experimental results from our collaborators and from the literature.
(Invited) Reversible Asymmetric Structure Evolution and Battery Performance in Layered Sodium Transition Metal Oxides
Authors: Li Xin
Published: February 2020

Layered sodium transition metal oxide system of NaMO2 (M = 3d transition metal ions and their mixtures) forms a unique material platform to study the interactions between transition metal, oxygen and sodium sublattices. Specifically, Fe and Mn, which are not stable in layered LiMO2, become much more stable in NaMO2. In this talk, I will show that the interplay between these different sublattices at low Na composition modulates the electrochemical performance of NaxMO2 through the generation of novel high voltage phases. A combined in situ (synchrotron) XRD, X-ray absorption spectroscopy, atomic resolution (scanning) TEM, neutron diffraction and density functional theory (DFT) simulation techniques are used to understand the structural and functional details in crystallographic, electronic and magnetic properties. For the Fe containing mixed transition metal system of Na(FexTM1-x)O2, a rippling phase at high voltage was developed due to the unique electronic property of FeO6­ octahedra, while at low voltage it goes back to the normal flat phase through an asymmetric structural evolution pathway, giving high discharge rate capability. For NaMnO2 a unique phenomenon of super charge separation is reported, where an emergent structural unit of charge superplane related to the collective Jahn-Teller activity of Mn3+ was found to dominate the entire electrochemical evolution, giving asymmetric charge discharge behavior and high discharge capacity. The underlying connection between these reversible asymmetric systems will be discussed to further facilitate the design of advanced cathode materials for sodium ion batteries.

[1]Advanced Functional Materials, 1805105 (2018)

[2]Advanced Functional Materials, 1803896 (2018)
(Invited) Room Temperature All Solid State Sodium Batteries Based on Glassy Electrolytes
Authors: Meng Ying Shirley
Published: February 2020

All solid-state batteries (ASSB) are regarded as a promising alternative to replace state-of-the-art liquid electrolyte-based batteries. Lithium-ion containing electrolytes are undoubtedly the most successful chemistries to date. However, taking material abundance into consideration, lithium sources are relatively limited and thus the Li compounds are costly to produce. In contrast, sodium sources are considered readily accessible. This makes sodium battery chemistries attractive and justifies their ongoing development targeting the large-scale energy storage. Until recently, the most widely adopted sodium solid electrolytes are NASICON and β-Alumina, with commercial applications of the latter in niche markets. However, demands for high power and cheaper processing have made the class of electrolytes based on Na3PS4 a more promising solid-state electrolyte (SSE) candidate for energy storage and conversion applications. I will discuss the synthesis, modification, interfacial engineering and electrochemical engineering of the ASSB based on this type of electrolytes. New characterization toolkit such as cryo-FIB/SEM and cryo-TEM are indispensable tools for studying the electrode / electrolyte interphases in the room temperature ASSB sodium batteries.
Tailoring Materials Chemistry to Advance Low Temperature Molten Sodium Batteries
Authors: Spoerke Erik D. , Percival Stephen , Peretti Amanda , Small Leo J.
Published: February 2020

The global implementation of secondary lithium ion (Li-ion) batteries continues to expand rapidly, finding clear utility in portable electronics and vehicle electrification. For large format, grid-scale energy storage however, concerns over the safety, reliability, cost, and lifetime of these batteries has motivated the drive to find alternatives to Li-ion systems. Here we describe the materials-driven development of a low temperature molten sodium-halide battery for grid-scale applications. Molten sodium batteries, such as sodium sulfur (NaS) and sodium nickel chloride (Na-NiCl2or ZEBRA) batteries, continue to show promise for grid-scale applications, valued for their use of earth abundant chemistries, scalability, and the absence of volatile, potentially hazardous organic electrolytes. Widespread implementation of these batteries has been limited, however, by relatively high operating temperatures (~300°C). Potentially impacting both cost and lifetime of these batteries, lowering the battery operating temperature would reduce material degradation, enable the use of lower cost battery components, and facilitate simplified, more cost effective heat management and operating strategies. The promising low temperature system described here comprises a molten sodium anode, a solid state ion-conducting separator, and a sodium iodide (NaI)-based molten salt catholyte. This NaI-based system avoids the hazards of volatile organic electrolytes, employing a fully molten catholyte designed to enable long cycle life while still offering a higher voltage (>3V) than traditional molten sodium batteries. Here, we will describe promising demonstrations of prototype battery cycling at drastically reduced operating temperatures near 100°C. In addition, we will address new materials challenges unique to operating a molten sodium battery at these reduced temperatures. In particular, we will focus on the complex goal of increasing lower temperature separator conductance in mechanically robust solid state electrolytes while minimizing resistances at interfaces between these separators and the molten anode and catholyte. Tuning separator materials chemistry and microstructure, both in the bulk and at separator interfaces, can significantly impact electrolyte wetting, reduce cell resistance, and improve battery cycling performance. Continued development of these emerging molten Na-NaI batteries promises a new route to the type of safe, cost-effective, long-lifetime batteries needed for grid-scale energy storage.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Earth Abundant Iron-Based Fluoro(hydroxy)Phosphate As Cathode Materials for Aqueous Batteries
Authors: Sharma Lalit , Okada Shigeto , Barpanda Prabeer
Published: February 2020

The quest for an efficient cathode material for batteries have shifted the focus from oxides to polyanion based materials. Polyanions not only impart thermal and structural stability to the material but also increases the voltage of the material due to high electronegativity of the central metal atom. A lot of research has been done on PO4-based materials especially when combined with other anions like F- or OH-. Moreover, safety and cost of existing organic electrolytes force us to revisit the possible application of aqueous electrolytes. Use of aqueous electrolytes reduces the toxicity and increases the ionic conductivity by two-fold. However, the limited working voltage window of aqueous electrolytes, to avoid water splitting, makes it important to look for materials that can function efficiently in the narrow voltage window. We hereby present two case studies using earth-abundant Fe-based materials. In the first case, Na2FePO4F is demonstrated as a cathode material for aqueous sodium-ion batteries. A discharge capacity of 85 mAh g-1 at 1 mA cm-2 current density with excellent rate kinetics was observed for half-cell configurations. A full cell was assembled with NaTi2(PO4)3 anode and the Na2FePO4F | NaTi2(PO4)3 full cell delivered a reversible capacity of 85 mAh g-1 working as a 0.8 V battery. The second work is based on LiFePO4OH, which works as an anode for aqueous lithium-ion batteries (LIBs). It has been reported as a 2.5 V battery cathode material for LIBs in organic electrolytes. However, it was found to be working in the anodic range for aqueous batteries. In half-cell configuration, it delivered a discharge capacity of 153 mAh g-1 with very good rate kinetics. [Figure 1(b)] A full cell was assembled with LiFePO4 as a cathode and an energy density of 70 Wh kg-1 was observed in the first cycle. The structural characterization along with electrochemical studies will be showcased for both case studies.

Figure 1: Galvanostatic (dis)charge profiles and cyclability of (a) Na2FePO4F, (b) LiFePO4OH in aqueous electrolytes in half-cell configuration.

Figure 1
Layered Iron Vanadate As a High-Energy Cathode Material for Nonaqueous Calcium-Ion Batteries
Authors: Chae Munseok S. , Setiawan Dedy , Kim Hyojeong J. , Hong Seung-Tae
Published: February 2020

Calcium-ion batteries (CIBs) are one of the promising candidates for post-lithium-ion batteries. However, only a few types of host materials are known to intercalate calcium ions reversibly in a nonaqueous electrolyte. Here, we demonstrate the electrochemical performances and evidence of calcium-ion intercalation into iron vanadate, FeV3O9∙xH2O, as a cathode material for CIBs at ambient temperature. FeV3O9∙xH2O was prepared via a facile water-bath method. It shows reversible calcium intercalation with a first discharge capacity of 334.4 mAh g−1 at 20 mA g−1 rate with an average voltage of ~2.26 V (vs. Ca/Ca2+) and excellent capacity retention in an electrolyte of 0.5 M Ca(ClO4)2 in acetonitrile. The high performance of the material with a layered structure and a wide range of vanadium oxidation states provides insights into the search for new oxide-based high-energy cathode materials for CIBs.
Investigation of the Kinetics of Rechargeable Aqueous Zinc Ion Batteries
Authors: Bischoff Christian , Fitz Oliver , Gentischer Harald , Biro Daniel , Henning Hans-Martin
Published: February 2020

Rechargeable aqueous zinc ion batteries are currently receiving much attention as large-scale energy storage systems due to their inherent safety, fast ion kinetics, low cost materials and environmental friendliness. Considering the recent literature, the state-of-the-art zinc ion battery combines a manganese oxide cathode, a planar zinc foil anode and an aqueous, mildly acidic electrolyte [1]. Even though the corresponding electrochemical models are subject to recent discussions [2] it is possible to derive basic kinetic parameters allowing a further development of the cell design and electrode composition. For this purpose in this study, zinc foil is used as the anode, a slightly acidic zinc sulphate solution as electrolyte and a stainless steel foil coated with manganese dioxide as the cathode. The coating process of the cathode may greatly influence the kinetics of the battery due to the fact that the cathode thickness, the porosity and the particle size are decisive for the overall performance of the battery. The cathode slurry is a mixture of manganese dioxide, carbon black, binder and distilled water. Previous studies showed that particularly the particle size of the manganese oxide in the cathode has great influence on the capacity of the battery [3]. In order to understand the kinetics of the coated cathode it was investigated if the electrochemical process is mass or charge transfer controlled and corresponding parameters of the Butler-Volmer equation are determined by electrochemical characterization of the samples. These kinetic parameters are identified in order to implement a simulation model allowing a further optimization of the battery cell architecture and the required electrode properties.

References

Liu, J.; Xu, C.; Chen, Z.; Ni, S.; Shen, Z.X. Progress in aqueous rechargeable batteries. Green Energy & Environment
2018, 3, 20–41, doi:10.1016/j.gee.2017.10.001.

Song, M.; Tan, H.; Chao, D.; Fan, H.J. Recent Advances in Zn-Ion Batteries. Adv. Funct. Mater.
2018, 28, 1802564, doi:10.1002/adfm.201802564.

Bischoff, C.; Fitz, O.; Schiller, C.; Gentischer, H.; Biro, D.; Henning, H.-M. Investigating the Impact of Particle Size on the Performance and Internal Resistance of Aqueous Zinc Ion Batteries with a Manganese Sesquioxide Cathode. Batteries
2018, 4, 44, doi:10.3390/batteries4030044.
Lithium-Ion Exchange Polymer Membranes Limit Migration of Dissolved Polysulfide Species in Li-S Batteries
Authors: Xu Hui , Moreira Mario , Laicer Castro , Harrison Katherine
Published: February 2020

Conventional lithium-ion (Li-ion) batteries dominate development efforts in electrical vehicles due to their high open circuit voltage, desirable power density, and long cycle life. Despite these advantages, state-of-the-art Li-ion batteries barely meet the energy requirement of EV-based power trains due low energy density (180-200 Wh/kg cell) and high cost. Lithium sulfur (Li-S) batteries are promising for EV applications because they address both these barriers. Li-S batteries exploit a redox couple described by the reaction below, which has an open circuit potential of 2.2 V with respect to Li+/Li:

16 Li+ + S8 + 16e-→ 8 Li2S

Assuming full conversion, the theoretical energy density and specific capacity of Li-S batteries is 2500 Wh/kg S and 1675 mAh/g S, respectively.1 In addition, sulfur, the key active cathode material is significantly less expensive than conventional transition metal oxide cathodes used in Li-ion batteries. However, Li-S batteries have not gained acceptance for practical applications because of their poor cycle life. This limitation originates from polysulfide diffusion from the cathode through the electrolyte to the anode which causes parasitic side-reactions and limits capacity and cycle retention.

Our work aims to overcome the challenges of polysulfide diffusion by incorporating lithium-ion exchange (LIE) ionomers as polysulfide blocking barriers in Li-S cells. When exposed to electrolyte solvent, these LIE membranes provide a physical barrier that limits polysulfide diffusion, while also delivering high Li+ ion conductivity through swelling in electrolyte solvent. The LIE ionomers can be applied in a variety of ways including as: binders in the electrode formulation, coatings applied directly to the electrode surface, and as freestanding polymer electrolyte membranes. We have also developed a porous, dimensionally stable membrane (DSM) which can be impregnated with LIE ionomers to improve mechanically stability by limiting in-plane (X-Y direction) swelling. This general approach of incorporating LIE ionomers into Li-S cells has achieved improvements in discharge capacity, cycle life, coulombic efficiency, and energy density.

References:

Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J.-M., Li-O2 and Li-S batteries with high energy storage. Nat Mater
2012,
11 (1), 19-29.
Investigating the Effect of Carbonaceous Host Materials on the Performance of Alkali Metal Composite Anodes
Authors: Kautz David , Lin Feng
Published: February 2020

Alkali metals (lithium, sodium, etc.) have been extensively investigated throughout the past several decades as potential anode materials for batteries. Their high theoretical capacities, low redox potentials, and low densities have garnered much attention and effort to yield highly efficient and capable anodes. These metals, through past efforts, have been shown to be highly reactive and unstable, forming layers of “dead” material, thick passivation layers, and producing dendritic structures. Within the past few years, the use of carbon host, support, materials have been employed to control the undesirable growths and reactions, and improve the efficiency and stability of the alkali metal anodes. While past results have shown to improve anode stability and performance, there have not been many studies to understand the fundamental interactions between the alkali metal and the host material. Utilizing a carbon fiber host material, we have observed disparities in the cycle life and performance between lithium and sodium metal. We employ characterization, electrochemical, and computational analysis to determine the differences of the host-metal interactions of lithium and sodium metal. Our results highlight the inherent properties and surface functionalization of the carbon host material that contribute to enhanced stability and performance of the composite anodes.
Rapid Li Diffusion By Ferroelectric Polarization for Smooth Lithium Deposition
Authors: Hwang Chihyun , Song Woo-Jin , Wu Yutong , Liu Nian , Park Soojin , Song Hyun-Kon
Published: February 2020

we demonstrated smart protective web consisted of nanosized beta phase polyvinylidene fluoride (PVDF) fibers with ferroelectricity on copper (Cu) foil to suppress Li dendrite. The beta phase PVDF fiber provides a well-ordered molecular structure, which ensures rapid Li-ion migration along PVDF fiber. That guarantee homogeneous Li-ions flux on the Cu current collector, leading to smooth Li surface occurs during Li deposition. In addition, the fiber could physically inhibit Li dendrite formation, resulting in no short-circuit and Li dead particle formation. Thus, the electrode consisted of PVDF fiber forms dense Li film during deposition, achieving high volume metric energy density (1937 mAh cm-3). In full cell (LFP||PVDF electrode (PVDF web on Cu current collector), the electrode exhibits an excellent cycle performance (over 300 cycles) using conventional carbonate electrolytes at a current density of 1C.
Nanostructured Metal Oxide Based Interlayers for Lithium-Sulfur Batteries
Authors: Zhao Teng , Chen Renjie , Kumar R Vasant
Published: February 2020

High-energy lithium-sulfur batteries are now earmarked as a viable means to meet the ever-rising demands of large-scale utilities and long-range electric vehicle.1 However, their commercialization has not come true yet due to the issues with the dissolution and diffusion of intermediate polysulfides in liquid organic electrolytes, which cause serious capacity degradation and low Coulombic efficiency. To solve these problems, a layer of material with nano-architecture, made from tiny metal oxides, is placed on the surface of sulfur cathode. As a proof of concept, zinc oxides (ZnO) nanowire arrays are grown on three-dimensional (3D) nickel foam and are used as an interlayer to enhance the electrochemical performance of Li-S batteries2. It is demonstrated that ZnO nanowires play a key role in chemically capturing polysulphides and remarkably mitigating capacity decay. After successful results, the foam was replaced by a lightweight carbon fibre mat to reduce the battery’s overall weight. Based on a similar design principle，a praline-like flexible interlayer consisting of titanium oxide (TiO2) nanoparticles and carbon nanofibers which allows the chemical adsorption of polysulfides to a robust conductive film. TiO2 nanoparticles, serving as anchors, can chemically detect and intercept polysulfides in-situ3. The porous conductive carbon backbone helps in the physical absorption of polysulfides and provides redox reaction sites to allow the polysulfides to be reused. A significant enhancement in cycle stability and rate capability has been achieved by incorporating our interlayer with a sulfur/carbon nanotube composite cathode. These results herald a new approach to advanced lithium–sulfur batteries using nanostructured metal oxide based interlayers.

Reference

1. Chen, R., Zhao, T. and Wu, F. Chemical Communications, 2015, 51(1), 18-33.

2. Zhao, T., Ye, Y., Peng, X., Divitini, G., Kim, H.K., Lao, C.Y., Coxon, P.R., Xi, K., Liu, Y., Ducati, C. and Chen, R., Advanced Functional Materials, 2016. 26(46), 8418-8426.

3. Zhao, T., Ye, Y., Lao, C.Y., Divitini, G., Coxon, P.R., Peng, X., He, X., Kim, H.K., Xi, K., Ducati, C. and Chen, R., Small, 2017, 13(40), p.1700357.

Figure 1
Instigation of Low Cost, Non-Toxic and Environmentally Benign Binders for Mild Aqueous Zn/MnO2 Systems
Authors: Chang Hee Jung , Pan Huilin , Choi Daiwon , Rodríguez-Pérez Ismael , Li Xiaolin , Reed David , Sprenkle Vincent
Published: February 2020

In recent years, zinc has gained significant attention due to its wide availability (fourth-most mined material on the Earth), low-cost nature and recyclability. Moreover, it allows water-based batteries (i.e. Zn/MnO2) that could compete with LIBs for both transportation and stationary applications without safety issues. However, they are not considered rechargeable in practice yet due to the capacity limitation from the cathode materials and the detrimental zinc dendrite formation.

Most of the electrode preparations are currently based on the use of fluorine-containing polymer binders, such as polyvinylidene difluoride (PVDF) and poly-tetrafluoroethylene (PTFE) with N-methyl-2-pyrrolidone (NMP) as a solvent/dispersant due to its good electrochemical stability and high adhesion to the electrode materials and current collectors. However, the fluorinated binders are relatively expensive and NMP is considered to be a hazardous and toxic substance. Therefore, switching to alternate electrode processing routes with non-toxic binders is crucial to providing a fully sustainable and environmentally friendly electrochemical energy storage device.

In this study, various water-soluble binders have been evaluated in mild aqueous electrolyte conditions for Zn/MnO2 systems and are compared with the conventional MnO2/PVDF systems. We observed water-soluble binders can be stable and offer desirable adhesion at certain pH levels (3.5~5) without any decomposition. Electrochemical data also indicates that higher capacity utilization and lower cell overpotential is achieved in the cells with aqueous binders versus the cells with PVDF binder. In summary, our work suggests that the implementation of water-soluble binders can lead to substantial improvements for efficient and effective aqueous battery systems.
In Situ Formed Li-B-H Complex Enables High-Performance Solid Electrolyte for Li Batteries
Authors: Zheng Shiyou , Pang Yuepeng
Published: February 2020

All-solid-state Li batteries are considered to be the next-generation high-density energy storage devices. The key material is the solid electrolyte with high Li-ion conductivity and wide electrochemical stability window. LiBH4 is considered as an alternative solid electrolyte due to its high conductivity (10-3 S cm-1 at 120 °C) and good electrochemical stability to Li anode. However, its main disadvantages are the low room temperature conductivity (< 10-7 S cm-1) due to the phase transformation at 110 °C and the poor electrochemical stability at high potential due to the strong reducibility. Searching for new types of Li borohydride beyond LiBH4 with superior Li-ion conducting properties is believed to be an effective strategy to push borohydride-based solid electrolytes towards practical applications. In this work, the Li-B-H complexes are facilely prepared via controllable dehydrogenation of LiBH4 as solid electrolytes for Li batteries. The Li-B-H complex with 7.5 wt% H2 desorption under 3 bar H2 (HP-LiBH2.4) shows exceptionally high Li-ion conductivity (2.7×10-4 S cm-1 at 35 °C) and low activation energy (0.43 eV). The Li-B-H complex possesses the best overall Li-ion conducting properties (in terms of Li-ion conductivity and electrochemical stability) among all borohydride-based solid electrolytes, and thus enables stable cycling of high capacity all-solid-state Li batteries at room temperature. In-depth characterizations demonstrate that the in situ formed interface layer between [Li2B12H11+1/n]n and LiBH4 is believed to be responsible for the high Li-ion conductivity. Moreover, this Li-B-H complex also exhibits excellent electrochemical stability, which enables the stable cycling of Li-TiS2 all-solid-state batteries at room temperature. Our results provide direct evidence for the exceptional Li-ion conductivity and electrochemical stability of Li-B-H complexes. This excellent performance plus the facile fabrication make this class of materials attractive for practical all-solid-state Li battery applications.

References:

[1] H. Maekawa, M. Matsuo, et al. J. Am. Chem. Soc., 2009, 131, 894.

[2] F. Lu, Y. Pang, S. Zheng, et al., Adv. Funct. Mater., 2019, 1809219.

Figure 1
Promising Lithium Metal Anode with Structured Design
Authors: Wu Sheng-Hui , Wu Wei-Hsin , Chao Chung-Hsiang , Chang Chih-Ching , Fang Jason
Published: February 2020

The advantages of lithium-metal batteries (i.e., a higher energy density and a smaller size) are known for over decades. However, these batteries have been so far non-rechargeable and have been known to burst into flame. These two characteristics stem from the reaction which takes place between the lithium metal and the battery’s electrolyte. This reaction not only produces compounds which increase the resistance in the battery and reduce the cycle life, but also forms mossy lithium-metal bumps on the anode which leads to short circuits. A short circuit generates high heat and ignites the flammable electrolyte. In order to suppress lithium dendrite formation, the formation of lithium needles needs to be prevented. This means that either the surface energy of the substrate must be completely homogenous, or the atom mobility must be reduced. There is no way that either of above mention can act as one antidote for lithium dendrite, but being a trade-offs instead. Eventually, a well distribution electro field and stable SEI having good ion conversion efficiency are both the keystone to the lithium anode preventing from dendrite formation and poor coulombic efficiency.
Origin of Low Performance of Lithium-Sulfur Batteries Under Lean Electrolyte Condition
Authors: Zhao Yifan , Guo Juchen
Published: February 2020

Lithium-sulfur (Li-S) battery is regarded as one of the most promising high-capacity rechargeable batteries, and the research and development on this technology has been active since the late 1960s. Benefiting from the resurrected efforts in the past decade or so, in-depth understanding and technologic know-how of Li-S technology have been accumulated thus leading to tremendous improvement of battery performance. However, wide deployment of Li-S batteries is still hindered by low specific energy and short cycle life. These challenges are dictated by the interplay of the Li anode, sulfur cathode and electrolyte in the battery. Particularly, implementing low mass ratio of electrolyte/sulfur (E/S ratio) is the most critical factor to realize high specific energy at cell level.

In this study, we assembled a 800 mAh Li-S pouch cell with specific energy of 275 Wh/kg and E/S ratio of 2.8. The sulfur loading was 5.4 mg/cm2 on aluminum foil and the specific capacity of sulfur is 1050 mAh/g. With these cell parameters, a 5Ah Li-S pouch cell with 350 Wh/kg specific energy can be delivered by simply incorporating more electrode layers. However, this promising pouch cell could only be cycled for less than 20 cycles. To understand the origin of the low performance under low E/S ratio, the interfacial resistance during the discharge was measured with electrochemical impedance spectroscopy with different E/S ratio. It was found, comparing to relatively high E/S ratio, low E/S ratio at 2.4 induced drastically increasing charge transfer resistance during the first discharge plateau, i.e. generation of high order polysulfides, which terminated the discharge of Li-S cells with low capacity. This observation was also confirmed by the Galvanostatic Intermittent Titration Technique (GITT) experiments. Based the results, we propose that the rate limiting step during the overall charge transfer can either the dissolution (solvation) of polysulfide anions or adsorption of solvated polysulfide anions to the electrode. The potential strategies to address the problem are also discussed.
Thermal Gradients through Sintered Solid State Electrolytes in Lithium-Ion Batteries
Authors: Bock Robert , Onsrud Morten Andreas , Karoliussen Håvard , Pollet Bruno G. , Seland Frode , Burheim Odne Stokke
Published: February 2020

Recent advancements in research have made solid state electrolytes a strong contender for the previously common liquid electrolytes, as it enables fast charging at very high current densities without flammable liquids. High current in combination with higher ohmic resistance lead to much more heat being dissipated than in conventional Li-ion batteries. As a result, large amounts of ohmic heat are produced inside the battery. As dry electrochemical cells have much lower heat conducting capacity than liquid-containing ones, knowing the thermal conductivity of the cell components plays a crucial role in predicting the heat distribution in such a cell.

Thermal conductivity was measured for three types of solid state electrolyte, Li7La3Zr2O12 (LLZO), Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and Li1.3Al0.3Ti1.7(PO4)3 (LATP) at different compaction pressures. LAGP and LATP were measured in sintered condition, LLZO was measured before and after sintering the sample material. Thermal conductivity for the sintered electrolytes was measured to 0.470 ± 0.009 WK-
1m-
1, 0.5 ± 0.2 WK-
1m-
1 and 0.49 ± 0.02 WK-
1m-
1 at 3 bar compaction pressure for LLZO, LAGP and LATP respectively. Before sintering LLZO showed a thermal conductivity of 0.22 ± 0.02 WK-
1m-
1 at 3 bar compaction pressure.

A simple analytical model of a lithium-ion battery cell stack was constructed to show the impact of the results obtained through the thermal conductivity measurements. It is based on a work by Richter et al. [1]. The resulting temperature profiles are shown in Fig. 1.

The temperature gradients inside the cell stacks need to be considered when assessing lifetime and degradation effects as seen in other electrochemical systems [2-4].

Figure 1: Temperature of the stack center compared to the outer boundary for a) a dry separator and b) a solid state electrolyte, each with two thicknesses.

References

[1] F. Richter, P. J. Vie, S. Kjelstrup, O. S. Burheim, Measurements of ageing and thermal conductivity in a secondary nmc-hard carbon li-ion battery and the impact on internal temperature profiles, Electrochimica Acta 250 (2017) 228 – 237.

[2] R. Bock, A.D. Shum, X. Xiao, H. Karoliussen, F. Seland, I.V. Zenyuk, O.S. Burheim, Thermal conductivity and compaction of GDL-MPL interfacial composite material, J. Electrochem. Soc. 2018 165(7): F514-F525

[3] R. Bock, H. Karoliussen, B. G. Pollet, M. Secanell, F. Seland, D. Stanier, O. S. Burheim, The influence of graphitization on the thermal conductivity of catalyst layers and temperature gradients in proton exchange membrane fuel cells, International Journal of Hydrogen Energy, In-press 2018

[4] O.S.Burheim, M.A. Onsrud, J.G. Pharoah, F. Vullum-Bruer, P.J.S. Vie, Thermal conductivity, heat sources and temperature profiles of Li-ion batteries, ECS Trans., 58 (2013) 145-171.

Figure 1
Electrochemical Stability Window of Polymeric Electrolytes
Authors: Chen Lihua , Venkatram Shruti , Kim Chiho , Batra Rohit , Chandrasekaran Anand , Ramprasad Rampi
Published: February 2020

The electrochemical stability window (ESW) is a fundamental consideration for choosing polymers as solid electrolytes in lithium-ion batteries. The inherent morphological and chemical intricacy of the polymer matrix and complicated interactions with lithium salts make the theoretical and experimental determination of polymer electrolytes ESWs difficult. Considering the dominant role of the polymer matrix in governing the ESW of polymer electrolytes, in this work, we propose a computational procedure to estimate ESW of the polymer matrix using first-principles density functional theory computations and classical molecular dynamics simulations. Taking polymer diversity and its utilization in Li-ion batteries into account, 10 model polymer matrix were investigated, namely, polyethylene, polyketone, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polycaprolactone, poly(methyl methacrylate), polyethyl acrylate, polyvinyl chloride, and polyvinylidene fluoride. Utilizing an increasingly complex hierarchy of models (i.e., the single-chain, ordered and disordered slabs), the role of polymer chemistry and the morphological complexity in determining ESW have been elucidated. We found that the former can modify the ESW by introducing different bonding/anti-bonding orbitals, while the latter can degrade the band edges, resulting in a decrease of ESW widths (i.e., the single-chain > ordered slabs > disordered slabs). Furthermore, a good agreement between computed ESW of disordered slabs and experimental values has been achieved, showing our computational procedures (DFT coupled with MD simulations) can successfully predict established ESW values of polymer electrolytes. Additionally, the proposed computational procedure and models lay the groundwork to systematically investigate impacts of lithium salts and electrode-electrolyte interfaces on the ESW parameters. All these contributions can assist the rational design of novel polymer electrolytes with desired ESW values.
Deciphering the Structure-Property Relationship in Sulfide-Based Solid Electrolytes for All-Solid-State Na-Ion Batteries
Authors: Xiong Shan , Liu Zhantao , Chen Hailong
Published: February 2020

Safety concerns on conventional lithium ion batteries are attracting a lot of attention from both academia and industry with the rapid growth of the electric automobile market. Replacing flammable organic liquid electrolytes with nonflammable inorganic solid electrolytes can potentially eliminate the fire hazards. On the other hand, low-cost electrochemical energy storage technologies beyond lithium chemistry are also highly desired for large-scale energy storage applications. All-solid-state Na ion batteries are one of the promising candidates for grid-level energy storage owing to their low cost and outstanding safety properties. The key enabler of this technology is solid electrolyte with sufficiently high ionic conductivity at room temperature and good electrochemical stability. This work presents a group of novel sodium superionic conductors to address the foregoing issues, which is a topic currently receiving extensive attention in the field of electrochemistry and energy storage.

Through a rational design approach and with using facile solid-state reactions, a series of novel Na4SnS4-Na3SbS4 solid-solution-based compounds with cation and anion substitutions were obtained. These sulfides show room temperature conductivities of 0.1~1 mS/cm, which is among the highest values reported for sodium ion conductors to date. The underlying structural factors, including lattice parameters, concentration of defects, local ordering, etc., of these compounds are investigated with a variety of characterization methods, including synchrotron X-ray diffraction, neutron diffraction, and pair distribution function analysis. Interesting structure-property relationships in these compounds were revealed. All-solid-state Na-ion battery cells using these as-synthesized materials as electrolyte was successfully assembled and cycled, demonstrating the promise of this group of sulfide-based compounds as solid electrolytes and implying new opportunities for materials and device development in solid-state batteries.
Garnet-Based Electrolytes for All-Solid-State Li-S Batteries
Authors: Zhou Chengtian , Thangadurai Venkataraman
Published: February 2020

Lithium sulfur (Li-S) batteries have emerged as one of the most promising post LIBs technologies with a remarkably high theoretical energy density and abundance of elemental sulfur. Nonetheless, there are several problems associated with Li-S batteries such as safety hazard due to lithium dendrite formation and fast capacity decay due to polysulfide dissolution effect.1 Employment of solid-state electrolytes is a promising strategy to address those issues.

Among different solid-state Li-ion electrolytes, Li-garnet attracts a lot of attention as it has a wide electrochemical window (> 6 V vs. Li/Li+), and high ionic conductivity (~ 1 mS cm-1) at room temperature. However, the application of garnet is hampered by its interfacial resistance against electrodes.2 In order to the reduce the interfacial area specific resistance (ASR) of Li/garnet interface, we devised a surfactant-processed interlayer for ceramic electrolytes (SPICE) method which can uniformly deposit a layer of ZnO onto the garnet surface. This process improves the wetting of Li and reduces the interfacial ASR to 10 Ω cm2 at room temperature.3 Stable Galvanostatic cycling of Li/garnet/Li at current densities up to 0.5 mA cm−2 was conducted, which presents a compelling method to solve the Li/solid electrolyte interface problem.

Another strategy we applied is incorporating garnet into polymer matrix to fabricate a flexible hybrid electrolyte. Polymer-based electrolytes possess low interfacial resistance due to its intimate contact with electrodes.4 The hybrid electrolyte merging the merits of garnet and polymer has been successfully employed in all-solid-state Li-S batteries operating at room temperature. Toward improving the energy density of the battery, we are working on tuning the cathode structure to effectively load more sulfur active materials. In this presentation, the SPICE method to tailor the interfacial resistance and the performance of all-solid-state Li-S batteries based on hybrid electrolyte will be discussed.

Manthiram, A.; Fu, Y.; Chung, S.; Zu, C.; Su, Y. Chem. Rev.
2014, 114, 11751-11787.

Han, X.; Gong, Y.; Fu, K.; He, X.; Hitz, G.; Dai, J.; Pearse, A.; Liu, B.; Wang, H.; Rubloff, G.; Mo, Y.; Thangadurai, V.; Wachsman, E.; Hu, L. Nat. Mater.
2016, 16, 572-579.

Zhou, C.; Samson, A.; Hofstetter, K.; Thangadurai, V. Sustainable Energy & Fuels
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2018, 3, 2181-2198.
Synthesizing a Novel Janus Carbon Nano-Onions Modified As a Support for Electrocatalytic Nanoparticles
Authors: Del Valle-Perez Angelica , Gonzalez-Aponte Kattia Mitchelle , Reyes-Morales Joshua , Escalera-Torres Yashira N , Cunci Perez Lisandro
Published: February 2020

Carbon materials have been awakening scientific interest for research because it allows chemical functionalization for multiple applications in the sciences, especially in energy applications. Carbon Nano-onions (CNO) are spherical structures composed of multilayers of fullerenes, these layers are connected in a way that show a shape of an onion. Its development begins with the use of nano-diamonds, a carbon material of strong structure which it forms in a very violent environment. The nano-diamonds are taken to a furnace at a temperature of 1650°C to finally obtain the CNO. Janus particles are receiving increasing attention because of their dual properties, where each side can be functionalized to have distinctive characteristics. The modifications on the surface of these nanoparticles can provide different chemical and physical properties. The interesting properties about Janus nanoparticles are that they have different sizes and shapes which have now been able to be studied in more detail. The modifications on the surface of these nanoparticles can provide different chemical and physical properties. The purpose of this project is to use asymmetrically modified CNO as a support for metal nanoparticles to avoid agglomeration and, thus, increase their surface area and efficiency. Janus nanoparticles will be designed by a wax-paraffin pickering emulsion process using CNO on its surface. The deposition of Platinum (Pt) it was carried out by an electrochemical process using the Rotating Disk Electrode. The removal process of the paraffin involves the dispersion of the wax-paraffin/CNO-Pt particles in Chloroform and rinse with ethanol to finally obtain the amphiphilic nanoparticle. The differences on the surface of the particles before and after removing the paraffin were observed by Scanning Electron Microscopy. The Energy-Dispersive Spectroscopy was used to validate the elemental information of the particles and assure the deposition of 20% of Pt on the surface of the particles. The Chronoamperometry technique was used for the reduction process of Pt. This process was carried out at a potential of -0.2v for 4 hours. Cyclic Voltammetry was used to characterize the surface of the electrode providing information about what is happening on the electrode surface. It was possible to validate that the Pt deposition process is taking place on the particles and not on the surface of the electrode. The voltammogram show the differences before and after the electrodeposition of Pt on the wax-paraffin/CNO particles. Thermogravimetric Analysis were used as a characterization technique to corroborate 20% of Pt on these particles. Characterization techniques as X-ray Diffraction and Raman Spectroscopy was used to validate the deposition of Pt on the particles.
Mwcnts-COOH/Cotton Flexible Supercapacitor Electrode Prepared By Improvement One-Time Dipping and Carbonization Method
Authors: Hao Tianqi , Wang Wei , Yu Dan
Published: February 2020

In the field of soft electronic devices, flexible supercapacitor has received dramatical attention due to their appealing properties like lightweight, flexible, and environment friendly. To get the ideal flexibility of the supercapacitor, it is a key point to get a solid flexible substrate, which not only preserve the original physical properties of fabric but also offers self-supported scaffold for active materials. Among the different flexible substrate, cotton fabric is a good choice owing to the properties like low price, easily available and hydrophilicity, in which the hydroxyl groups make it favorable for adsorbing water and reacting with active materials.

Carbon nanotubes are widely used electrode materials with the merits of high specific surface area, good chemical stability, low resistance, thermal stability, high flexibility and excellent electrical properties. However, it is hard to obtain ideal properties only combining carbon nanotubes with cotton, because the low capacity of carbon nanomaterials. Herein, we proposed a new method to prepare flexible carbon materials with high capacitance.

First, we prepared flexible supercapacitor electrode based on carboxyl functionalized multiwalled carbon nanotubes (MWCNTs-COOH) and cotton fabric by a facile and highly efficient one-time dipping method under the condition of high pressure and temperature. After this process, MWCNTs-COOH coated on cotton fiber uniformly and winding together because of the presence of electrostatic interaction, van der Waals’ force and hydrogen bond between the oxygen-containing functional groups on MWCNTs-COOH and cotton fibers.

Second, the sample was dipped in solution of poly(ethylene oxide) (PEO) for improving the carbon content and strengthen the composite structure after carbonization. At last, the above sample was dealt with pre-oxidation and carbonization to get the final composite. Pre-oxidation was used to induce oxygen-containing groups and obtain stable skeleton. Carbonization is beneficial to increase the carbon content and get stable structure with bitter melon surface-shape, which can supply large specific area and mesoporous to store and transport electrons, leading to a high capacitance.

Therefore, the composite possessed excellent electrochemical performance with a high capacitance of 94.3 F g-1 at a current rate of 0.81 A g-1, and a good capacitance retention with over 96% after 3000 cycles. The prepared flexible supercapacitor electrode also showed good flexibility (93% capacitance retention after bending 60 times). Considering these good electrochemical performances, they are expected to be useful for practical applications in the field of supercapacitor.

Figure 1