bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Temperature Synthesis of Nanophosphors for White Light Emission
Authors: Zhang Ying , Dai Qilin
Published: February 2020

Nanophosphors are considered to be very critical for the development of lighting and display due to some new features from nanosized materials compared to bulk phosphors, for example, surface-site luminescence. The current methods to synthesize nanophosphors are based on high temperature methods, such as hydrothermal method, co-precipitation method, and so-gel method. Usually, temperature dictates the nanocrystals growth speed, which may affect the size and crystallinity of the nanocrystals. pH value is another very important parameter to control the nanocrystal growth, which is believed to be associated with nanomaterial morphology and structure. In our work, we developed a low temperature (2oC) method to synthesize some tungstate nanophosphors, for example CaWO4:Eu, in aqueous solution under different pH values. Nanowires, nanorods, nanospheres are obtained by the developed low temperature synthesis method. Self-assembled microstructures and isolated nanoparticles can be obtained by controlling the pH values. Nanowires are produced as the Eu doping concentration is 10%. For comparison, high temperature synthesis method (150oC) are also used in the synthesis of tungstate nanophosphors. The influence of temperature, pH vales and Eu doping concentrations on the luminescence properties of tungstate nanophosphors are systemically studied, and the mechanism of the luminescence are demonstrated. Small sized nanophosphors are produced as the synthesis temperature is 2oC compared to high temperature. The photoluminescence of CaWO4:Eu includes the green-blue emission band due to the tungstate group in the host and the red emission peaks from Eu3+. The relative intensity of the green-blue emission to the red emission can be considerably tuned by the pH values, which affects the energy transfer efficiency from tungstate group to Eu3+. Eu doping concentration also can be used to adjust the color of the luminescence of tungstate nanophosphors. We optimize the parameters including pH vales, and Eu doping to obtain the white light emission. Figure 1 shows the color coordinates of the nanophosphors prepared by us. It can be seen that the range of color coordinates can be tuned by our method covers blue, green, white, red and yellow regions, which shows the feasibility of our method for the synthesis of nanophosphors toward white light. Low reaction temperature synthesis method provides a platform to synthesize the nanophosphors toward color tunable and while light emission for lighting and display.

Figure 1: color coordinates of the luminescence of CaWO4:Eu nanophosphors

Figure 1
Effect of Surfactants on Structural, Morphological and Luminescent Properties of Gd2O3:Eu Phosphors
Authors: Priya Ruby , Pandey O. P.
Published: February 2020

In the present work, Gd2O3:4mol%Eu were synthesized via co-precipitation route. The concentration of Eu ions was fixed to avoid the chances of concentration quenching. The effect of cationic surfactants (CTAB, DTAC), anionic surfactants (SDS, SDBS) and non-ionic (PEG, PVP) surfactants on the morphological, structural and luminescent properties have been studied in detail. The as-synthesized phosphors were characterized by X-ray diffraction technique, Field emission scanning electron microscopy, Fourier transformed infrared spectroscopy, UV-Vis spectroscopy, Vibrating sample magnetometer, and photoluminescence technique. All the as-synthesized phosphors were illuminated under UV excitation at 254 nm and emitted red emission at 612 nm which is characteristic of Eu ions. The addition of surfactants alter the morphologies but did not alter the crystal structure. The as-prepared phosphors are expected to be promising candidates for bio-medical applications, contrast agents and bio-sensors.
Multifunctional Gel Polymer/Microspheres Composite Electrolyte Coated Separator for Lithium Metal Batteries
Authors: Ryu Saebom , Choi Jang Wook , Sugimoto Toshinori , Lee Yong-Gun , Im Dongmin
Published: February 2020

Lithium (Li) metal has received much attention as a promising anode candidate in recent years with the increasing demand for high-energy-density rechargeable batteries in industrial fields. However, unlike current graphite anodes where Li ions are intercalated, metallic Li anodes generate Li deposition forming an uneven anode surface and have high reactivity toward organic electrolytes. This can cause safety concerns including cycling instability. Thus, developing a stable electrolyte and its corresponding separator is widely recognized as a major challenge to the practical application of Li metal batteries. Although there remains a need for improving the separator performance because of poor separator wettability for highly viscous electrolytes, little work has been done about the separator structure design to ensure proper wettability and stability [1].

In this study, we propose a high performance composite coated separator for Li metal batteries. A commercial separator was thinly coated with a mixture of block copolymer, ionic liquid, and microspheres. The composite electrolyte coated separator showed significantly enhanced wettability which is sufficient to adsorb highly viscous electrolytes. To improve the mechanical properties of the separator, microspheres with high rigidity and stability to organic electrolyte [2] were used. The tensile strength and thermal stability of the separator were improved by microspheres and block copolymer. This approach appears to be effective in improving battery safety by inhibiting the growth of Li dendrites. Due to the increased wettability and enhanced mechanical properties, the cycle life of the cell was greatly improved when our separator was applied. In addition, unlike the ceramic component with a poor dispersion in the coating solution, our novel coating blend enables cost-effective production with rapid and uniform coatings with its excellent dispersion stability.

[1] M. H. Ryou, Y. M. Lee, J. K. Park, and J. W. Choi, Adv. Mater., 23, 27 (2011).

[2] Y. G. Lee, S. Ryu, T. Sugimoto, T. Yu, W. S. Chang, Y. Yang, C. Jung, J. Woo, S. G. Kang, H. N. Han, S. G Doo, Y. Hwang, H. Chang, J. M. Lee, and J. Y. Sun, Chem. Mater.,
29, 14 (2017).
Factors Affecting Contact Resistance between Electrode and Current Collector
Authors: Sederholm Jarom Glen , Vogel John E. , Mazzeo Brian , Wheeler Dean
Published: February 2020

Contact resistance between the battery film and its current collector should be minimized in order to fully optimize battery electrodes. Increased resistance results from any factor limiting electrons from transitioning between the current collector and porous electrode materials, such as increased pockets of void space, depletion of conductive additive, or formation of resistive corrosion products.

This work explores the effect on contact resistance of changes in battery aging, treatment, and film drying rates. The levels of aging include uncycled, lightly cycled, and heavily cycled electrodes. Battery treatment comparison is between the films treated with and without the commonly used oxalic acid [1]. The drying rates are varied through use of three different drying temperatures. Measurement of contact resistance is done using a four-contact microprobe previously utilized by our group [2]. Results from this measurement require a computer model to interpret. We will also compare resistance to peel strength test results.

An understanding of conditions affecting contact resistance allows one to decrease contact resistance of battery electrodes during various production stages and know to what degree aging will affect battery performance.

[1] Zhi Zhu et al. Journal of Power Sources
224, 13-19 (2012).

[2]J.E. Vogel et al. Electrochimica Acta
297, 820-825 (2019).
Electrochemical Kinetics of Degradation of Carbon Anodes in Lithium Ion Batteries
Authors: Das Supratim , Bazant Martin Z.
Published: February 2020

Growth of the solid electrolyte interphase (SEI) is a major driver of capacity fade in LIBs. Despite its importance, the fundamental mechanisms remain unclear, primarily because of the complicated reaction pathways involved. SEI growth can be both electrochemical and chemical in nature, and thus, it is a strong function of the potential and degree of lithiation of the electrode. In this work, we model the early-stage and long-term growth of SEI by accurately capturing the potential dependence of its formation kinetics as well as long term rate limiting steps, and validating it against extensive experimental data. This is done using the Multiphase Porous Electrode Theory (MPET) framework on graphite (phase separating) and carbon black (non phase separating) particles. Results indicate that the peak SEI-forming currents are higher for higher driving currents. Counterintuitively, despite higher peak SEI-forming currents, the highest differential capacities or ‘extent of SEI growth’ are seen for lower driving currents, which implies that SEI formation is a stronger function of potential and cycling time, than the driving current. This work holds promise for the predictive design of procedures for manufacture and formation of LIBs.
Gas Formation and Crossover Effect in High Voltage Li-Ion Full Cells with Ni-Rich NMC Cathodes
Authors: Geng Linxiao , Mao Chengyu , Ruther Rose E. , Wood David L. , Belharouak Ilias
Published: February 2020

High voltage high energy cathode materials for Li-ion battery are highly needed. High nickel content NMC (e.g. NMC811) is believed to be a promising candidate. When raised the upper cutoff voltage of NMC811 cathode to 4.5 V vs. Li+/Li, the cathode materials could deliver a capacity above 215 mAh g-1, which is very attractive to the electric vehicle application. However, raising the upper cutoff voltage will also greatly accelerate the capacity fade of the full cell. Of the various causes proposed by the battery community, a large volume of gases generated at high voltage is believed to be one of the major issues. In this study, we constructed full pouch cells composed of graphite anode, NMC811 cathode and standard GEN2 electrolyte which is 1.2M LiPF6 in EC/EMC (3/7 by weight). We also constructed anode and cathode symmetric pouch cells to investigate the gas evolution and crosstalk at specific sides. Using Archimedes’ Principle, we measured the generated gas volume along cycles within the pouch cells with different cutoff voltages. We found out that the full cells using 4.2 V cutoff voltage barely generated gases along the course of 100 cycles while the ones using 4.4 V cutoff voltage generated a large amount of gases in the first 20 cycles, but the gases would be gradually consumed in the subsequent cycles. By using GC-MS, we determined the main gas species generated in the full cell to be carbon dioxide and alkanes. Moreover, the relative amount of carbon dioxide decreased along cycles while the amount of alkanes would increase. In cathode symmetric cells, CO2 remained the major component after 100 cycles and its signal was much stronger than in full cells. Interestingly, some fluorinated alkanes not seen in the full cells were also identified in cathode symmetric cells, suggesting potential involvement and loss of LiPF6 from electrolyte due to the parasitic side reactions on the cathode. In anode symmetric cells, hydrocarbons attributed to electrolyte decomposition were the main products. Unlike CO2 and fluorinated alkanes formed on the cathode, these species were relatively stable and remained in the full cell after extensive cycling. It was also shown that gas crossover to the anode leads to the depletion of gaseous products during cycling, which could stabilize the cell cycle performance. Although some inactive surface reconstruction layer was formed on the cathode at high voltage operation, impedance buildup and active lithium inventory loss contributed to the significant capacity loss in the full cell. Our study revealed the important role of crossover effect in stabilizing Ni-rich layered oxide cathode, and provided a better understanding on capacity fading to take more effective measures for improving the full cell cycle life.
The Effect of Functional Groups and Co-Additives on the Performance of an Electrolyte Additive for Li-Ion Cells
Authors: Gauthier Roby , Hall David S , Hynes Toren , Dahn Jeff R.
Published: February 2020

It is very common to add additives in lithium-ion cells in order to improve their performance. However, it is not well-known what makes a good additive. The goal of this research was to study how different functional groups in the para position affect the performance of the relatively new additive PDO (3-phenyl-1,4,2-dioxazol-5-one). The PDO additive was developed following previous work by the Winter group on MDO (3-methyl-1,4,2-dioxazol-5-one)1. Each PDO-type additive was synthesized in our lab from the corresponding acyl chloride and was tested in NMC622/graphite cells. Differential capacity analysis (dQ/dV), electrochemical impedance spectroscopy (EIS), high-temperature storage, and long-term cycling tests have been used to characterize the corresponding cells. The well-known additives DTD (Ethylene Sulfate), MMDS (Methylene Methyl Disulfonate), LFO (Lithium difluorophosphate) and VC (Vinylene Carbonate) have been added as co-additives in the hope of forming binary blends with improved performance. It was found that unsubstituted and nitro-substituted PDO blends have the best long-term cycling performance, while unsubstituted and methoxy-substituted PDO blends have the best storage performance at 60°C.

S. Röser, A. Lerchen, L. Ibing, X. Cao, J. Kasnatscheew, F. Glorius, M. Winter, and R. Wagner, Chem. Mater., 29, 7733–7739 (2017).

Figure 1
Electrochemical Aperture Enabling Rapid Delivery of Liquid Electrolyte for Lithium-Ion Reserve Batteries
Authors: Liu Danny X. , Snyder Stephen , Hall Timothy D. , Inman Maria , Taylor E. J.
Published: February 2020

Reserve batteries fulfill a unique role among energy storage technologies in which long-term shelf life (years, decades) is required while ensuring optimal performance upon activation. This is typically achieved through isolation of the electroactive components until battery operation is required. Commonly, the electrolyte is isolated from one or both electrodes, and thus, limiting premature degradation and parasitic side-reactions until battery activation is desired. During the reserve battery activation process, electrolyte is delivered to the electrode(s), which enable ionic conduction between the anode and cathode, and thus permitting normal operations analogous to a non-reserve design.

The feasible activation mechanisms are largely determined by battery chemistries and material properties, which give rise to several classifications including: thermal, spin-activated, and gas-activated reserve type batteries. Reserve battery activation under these various classifications require ancillary components and/or specific conditions which contribute excess complexity, weight, and/or volume towards the overall battery design and thus, significant penalties in reliability, specific and/or volumetric densities are incurred. Improvements in reserve battery technology must include strategies for limiting these penalties through innovated electrolyte delivery designs tailored for modern, high-energy, high-power density lithium-based batteries.

Herein, we report a novel electrolyte delivery mechanism facilitated by an electrochemical aperture. The electrochemical aperture exists as a physical barrier, isolating the liquid, lithium-containing electrolyte. Reserve battery activation proceeds via lithium transport to/from the electrochemical aperture, thus inducing physical transformations which permit liquid electrolyte permeation and delivery through the aperture and into the appropriate compartment, thus establishing ionic conduction between the anode and cathode. The accompanying figure highlights the lithium electrochemical aperture (LiECA) in a 3-electrode cell. During the inactive period (a), liquid electrolyte is isolated by the LiECA and stored within the cathode compartment. Electrochemical transport of lithium between the LiECA (b) and cathode induces aperture opening and injecting electrolyte into the anode compartment (c), and ultimately resulting in battery activation and operation.

Acknowledgements: Faraday Technology acknowledges the technical assistance of Dr. Joseph P. Fellner at the Air Force Research Laboratory, Wright-Patterson AFB (Dayton, OH) under Air Force Contract No. FA8650-19-P2024 (Phase I SBIR program).

Figure 1
(Battery Division Postdoctoral Associate Research Award sponsored by MTI Corporation and the Jiang Family Foundation) Toward the Stable and Reversible Lattice Oxygen Redox in Li-Rich Layered Oxides
Authors: Meng Shirley , Zhang Minghao
Published: February 2020

Conventional wisdom on utilizing cation redox in intercalation materials for energy storage has been challenged by a new class of cathode materials where oxygen anions actively participate in the reversible electrochemical reaction. This type of Li-rich layered oxides (LRLO) have captured great interests in the field of energy storage materials as they are considered as one of the most promising cathode materials for future high energy density lithium-ion and lithium metal batteries. However, the activation of solid-state oxygen redox reaction usually causes some detrimental effects on the electrochemical performance (e.g., O2 loss, voltage fade) preventing the practical application of LRLO (Y. S. Meng et al., Nature Energy, 2018, 3, 641-647; X. Yu et al., Nature Energy, 2018, 3, 690-698). Till now, the charge-compensation mechanism associated with oxygen reduction/oxidation is still under fierce debate. For instance, J.M. Tarascon et al. proposed the presence of peroxo-like species (O2
n-, O-O: 2.45 Å) in lattice oxygen redox based on the research results of 4d/5d-TM LRLO (Science, 2015, 350, 1516-1521; Nature Materials, 2017, 16, 580-586). In contrast, P. Bruce et al. clearly demonstrated that there is no peroxide species formed in 3d-TM LRLO (Nature Chemistry, 2016, 8, 684-691). The controversial viewpoints regarding oxygen reduction/oxidation at solid state may be originated from the intrinsic complexity of this class of materials and the limitations of the characterization techniques.

Our work reveals the origin of stable and reversible lattice oxygen redox in 3d TM LRLO, specifically, the localized structure distortion (i.e., short O-O pairs) accompanying the oxygen redox is favorable for the stability of the average layered lattice structure, maintaining the high-voltage character and topotactic structure-reversibility of LRLO. With a model compound (Li1.2Mn0.54Co0.13Ni0.13O2), we for the first time observe a local occurrence of short O-O pair (~2.39 Å) concomitant with the lattice oxygen redox via neutron pair distribution function. It was found that the distance of this short O-O pair is very similar to that of O-O dimer in peroxo-like species, but our quantum mechanical calculation results suggest that the bonding nature of this short O-O pair (in which potential π-type overlap dominated) is quite different from that of peroxo-like O-O dimer (in which σ-type bond formed). Based on these understandings in our work, an optimization guidance for LRLO is unambiguously presented: designing a robust layered structure with high-covalency TMs while constructing a flexible local structure (e.g., honeycomb structure) with high-ionicity TMs to accommodate the local distortion induced by oxygen redox, thus achieving the reversible high energy density in LRLO.

Figure 1
Ultrasmall Sn Nanodots Dispersed in Cross-Linked N-Doped Carbon Cages for High-Performance Lithium Storage
Authors: Ying Hangjun , Han Weiqiang
Published: February 2020

Sn based materials are the promising anodes in Li-ion batteries for the advantages of high theoretical capacity (994 mAh g-1 for LIBs), high conductivity and low cost. However, the drastic volume change during charging and discharging process results in poor cycling stability. Dispersing nano-sized Sn particles in carbon matrix is an effective way to mitigate the volume change, but the thick carbon matrix may retard ion diffusion. Consider this, we designed nano-Sn/N-doped carbon microcages composites (Sn/NMCs) with Sn nanodots uniformly dispersed inside the N-doped carbon microcages through a simple spray drying process, followed by thermal treatment. The interconnected N-doped carbon skeleton enhances the electronic conductivity, meanwhile the internal channels supply fast paths for Li+ transmission. Taking the advantages of ultrasmall Sn and soft carbon matrix, the Sn/NMCs exhibit excellent electrochemical performance as Li-ion battery anode. It delivers an initial charging capacity of 780 mAh g-1 at 200 mA g-1, and maintains 472 mAh g-1 after 500 cycle.; 323 mAh g-1 is still maintained even at a high current density of 10 A g-1. Moreover, this Sn/NMCs is accessible to scale up and the modification strategy can be extended to other electrode materials.

Figure 1 TEM image of Sn/NMCs and the schematic diagram of Li+ and electron transportation processes in Sn/NMCs

Acknowledgments

This work is supported by the National Natural Science Foundation of China (Grant No. 51371186), the “Strategic Priority Research Program” of the Chinese Project Academy of Science (Grant No.XDA09010201), Ningbo 3315 International Team of Advanced Energy Storage Materials, Zhejiang Province Key Science and Technology Innovation Team (2013TD16).

Figure 1
Understanding the Role of Fluoroethylene Carbonate As a Electrolyte Additive in Silicon Anode Lithium-Ion Batteries
Authors: Pathak Anil Daliprasad , Samanta Kousik , Sahu Kisor Kumar , Pati Soobhankar
Published: February 2020

Silicon is regarded as one of the most promising anode material for lithium ion batteries (LIBs). It has a high theoretical capacity of 3579 mAh/g. In order to make silicon commercially viable, the two key challenges need to be addressed: high volume expansion during lithiation/delithiation process and formation of unstable solid electrolyte interphase (SEI) at the silicon-electrolyte interface. Specially, to address the unstable SEI formation, different types of strategies are adopted such as; use of carbon coated silicon surface, use of nano-silicon materials, modification of the binder and use of additive in the electrolyte. Previous studies have reported1,2 that the fluoroethylene carbonate (FEC) additive improves the performance of the silicon anode. Although research efforts are focused on understanding the cause of improvement in the performance of LIBs with FEC electrolyte additive, the underlying mechanism mostly remains unclear.

In this work, we studied the effect of FEC additive on the performance silicon anode in half as well as the full-cell configuration of LIBs comprising NMC cathode and attempted to find the underlying mechanism. To complement the experimental results, we provide key insights from the first principle to uncover the role of FEC additive in silicon anode LIBs.

References

1. Dalavi, S., Guduru, P., & Lucht, B. L. (2012). Performance enhancing electrolyte additives for lithium ion batteries with silicon anodes. Journal of The Electrochemical Society, 159(5), A642-A646.

2. Nakai, H., Kubota, T., Kita, A., & Kawashima, A. (2011). Investigation of the solid electrolyte interphase formed by fluoroethylene carbonate on Si electrodes. Journal of The Electrochemical Society, 158(7), A798-A801.
For Battery Safety Sake: Operando Quantification of Lithium Concentration Gradients in the Graphite Anode of Li-Ion Cells Using Synchrotron Energy Dispersive X-Ray Diffraction
Authors: Yao Koffi P.C. , Okasinski John , Kalaga Kaushik , Shkrob Ilya A , Abraham Daniel P
Published: February 2020

Safe and energy efficient fast charging of lithium ion batteries is desired in many practical applications such as portable electronics and electrified transportation. However, diffusive transport modeling predicts steep intercalant gradients in the electrodes during high-current cycling. The heterogeneities in the electrodes created by these gradients negatively impacts battery lifetimes as mechano-chemical stresses develop in the structure of the cell’s electrodes. Direct experimental measurement of these gradients is lacking to steer pragmatic optimization of Li-Ion electrodes for gradient-free fast utilization. In this talk, we will discuss the novel use of spatially resolved energy dispersive X-ray diffraction to obtain a direct spatiotemporal "movie" of insertion and de-insertion in different sections of the cell and quantify gradients in lithium distribution that develop in a typical graphite electrode during one-hour full charges and discharges. We discovered, even at this moderate charge/discharge rate, that unexpectedly large spatial inhomogeneities in the ordered LixC6 phases and thereby in Li-content are prevalent causing mechano-chemical stresses in the cell. In the specific case of the typical graphite with reversible potential perilously close to that of metallic lithium, these steep gradients polarize the battery cell on charge and lithium plating conditions can be met near the electrode surface resulting in the potential for dendrite-induced short circuits and compromised fire safety.

Figure 1
Step By Step Process for Formulating a DFN Model for a Lithium Ion Full Cell Battery
Authors: Chipman Gregory Dan , Fuller Thomas F.
Published: February 2020

The Doyle Fuller Newman (DFN) model has commonly been used to simulate the behavior of lithium ion batteries. However, the ways that parameters for the model are obtained vary widely across the field. In extreme cases, parameters are determined from a minimal experimental data set that fails to consider the validity of the model for other experimental conditions. This can lead to parameters that only perform well for the specified experimental technique. A process is outlined for determining parameters for a DFN model of a lithium ion full cell battery that uses a wide variety of experimental techniques to ensure parameters perform well over a variety of experiments. A recommended order that the parameters should be determined in is also provided. A NCM-graphite full cell battery is used as an example for the outlined process. Experimental data from manufactured half cells for each electrode is used to determine OCV curves, conductivity, exchange current densities, capacitances, and diffusivities for graphite, 1 M LiFEPO4 EC/DEC (1:1) electrolyte, and NCM. Test procedures included GITT, current interruption, cycling, and EIS. The parameters determined for each electrode and the electrolyte from half-cell experiments are validated using experimental data from manufactured full cells. The final model parameters are compared to existing parameters in literature with key differences being highlighted as well as reasons that the differences may have occurred.
Mesoscale Implications of Electrode-Scale Heterogeneity on Performance and Degradation
Authors: Parmananda Mukul , Mistry Aashutosh N , Mukherjee Partha P.
Published: February 2020

Lithium-ion battery electrodes are pivotal to attaining high energy and power dense batteries towards vehicle electrification. These electrodes attribute spatial heterogeneity at different scales (particle, pore, electrode) stemming from the electrode processing steps. Particularly, the inhomogeneity in the negative electrode can be ascribed to the spatial variation of active material (graphite) and the polymeric binder. The inherent inhomogeneity at different scales can translate to non-uniform kinetic and transport resistance. These effects can foster higher over-potentials, restraint ionic transport with localized potential drop and heat generation. The localized heterogeneity coupled with anode centric degradation behavior can also facilitate preferential lithium plating. This study elucidates the mesoscale implications of the electrode-scale heterogeneity on the coupled thermo-electrochemical response in terms of performance and degradation.
Synthetic Vs. Real Driving Cycles: A Comparison of EV Battery Degradation
Authors: Baure George , Dubarry Matthieu
Published: February 2020

Automobile dependency and the inexorable proliferation of electric vehicles (EV) compels accurate predictions of cycle life across multiple usage conditions and for multiple lithium-ion battery systems.

Synthetic driving cycles have been essential in accumulating data on EV battery lifetimes. However, since battery deterioration is path-dependent, the representability of synthetic cycles must be questioned. Hence, this work compared three different synthetic driving cycles to real-driving data in terms of mimicking actual EV battery degradation.

It was found that the average current and charge capacity during discharge were important parameters in determining the appropriate synthetic profile and traffic conditions have a significant impact on cell lifetimes. In addition, a stage of accelerated capacity fade was observed and shown to be induced by an increased loss of lithium inventory (LLI) resulting from irreversible Li plating. New metrics, the ratio of the loss of active material at the negative electrode (LAMNE) to the LLI and the plating threshold, were proposed as possible predictors for a stage of accelerated degradation.

The results presented here demonstrate tracking properties such as capacity loss and resistance increase were insufficient in predicting cell lifetimes and support the adoption of metrics based on the analysis of degradation modes.
Nanoelectrochemistry Concepts in Desalination Energy Harvesting and Analysis
Authors: Wang Gangli
Published: February 2020

This talk will provide an overview of the research in GWang’s group at Georgia State centered around the electrochemical processes at the nanometer scale. Three examples will be discussed in two research topics. The first is the development of new analytical method/toolbox for actively controlled nucleation and crystal growth. By controlling charge transport through a single nanopore, a single crystal is synthesized while the whole process is monitored by combined electroanalytical and optical methods. In the second topic, ion transport through a single asymmetric nanopipette is studied by experiments and simulation. The solution-substrate interface confined inside the conical nanopore is viewed as structurally-defined unit elements in ensemble porous membrane/electrode/materials. The surface electric field direction is separated from the through-transport ion flux which affects both the structure and dynamics of the electrical double layer (EDL). Selective and efficient transport of ions is the fundamental process in 1. the desalination with energy input; and a retrospective process of 2. energy harvesting from salinity when fresh and brackish/sea water mix. Novel time-dependent current-potential features are captured in electrochemical experiments due to the polarization of the nanoscale EDL or selective transport of ions. Characteristic signatures include a non-zero cross point in I-V curves separating pinched hysteresis loops. Finite element simulations by solving the Poisson, Nernst-Planck and Navier-Stokes equations reveal the respective transport of cations and anions driven by migration, diffusion and electroosmotic flow. The transport selectivity and efficiency under time- and space- confined conditions provide fundamental insights to better transport related applications such as desalination separation and energy harvesting from salinity gradients. Financial supports from NSF (CHE-1610616) and DOE (DE-SC0019043) are acknowledged.
Environmental Perspective of Electrochemical Sensors
Authors: Ahamed Ashiq , Lisak Grzegorz , Bobacka Johan
Published: February 2020

Electrochemical sensors are increasingly used in portable single-use clinical, process and environmental quality monitoring systems. Commercially viable and scientifically reliable analyses require sensors that are easy to use and low cost, require limited maintenance, possess high selectivity and sensitivity towards the analyte, and have potential to be mass-produced. Thus, the current research focuses on sensors development to address all of the above mentioned requirements. On the other hand, owing to the increasing number of sensor applications, the spent sensors are identified as an emerging type of waste. The materials used for manufacturing of sensors are in most cases derived from fossil, often scarce sources, e.g. transition metals and carbon. Moreover, these materials are expensive and bear high carbon footprint.

In this work, we explore the use of waste-derived carbon material, such as CNTs, in order to decrease the environmental burden associated with the application of fossil derived carbon. The CNTs were produced from residues, e.g. waste plastics, which are abundant, inexpensive, and bear low or negative carbon footprint. This paper identifies the waste-derived CNTs as an environment-friendly alternative for use in sensors as they exhibited comparable performance to commercial carbon nanotubes and metal-based electrodes. The proposed alternative material provides valuable insights to the research and development of environmentally friendly alternatives for the sensor design and application.
Zinc Oxide-Carbon Cloth Nanosensors for Simultaneous Detection of Uric Acid, Epinephrine, and Ascorbic Acid
Authors: De Penning Rebekah , Monzon Noahlana , Fallatah Ahmad , Padalkar Sonal
Published: February 2020

We present a flexible, inexpensive electrochemical sensor using zinc oxide (ZnO) grown directly on carbon cloth for the simultaneous detection of uric acid (UA), epinephrine (EP), and ascorbic acid (AA). The simultaneous detection of these biomolecules poses inherent challenges since their concentrations in the human body are low and the obtained signals are difficult to deconvolve. These limitations were overcome by using nanostructured ZnO on three dimensionally woven carbon fibers as a high surface area biosensing platform. Additionally, a differential pulse voltammetry (DPV) detection technique was used to overcome the bottleneck of clearly resolving signals from UA, EP and AA. The results obtained demonstrate the simultaneous detection of UA, EP and AA. The lowest simultaneously detected concentrations were 2.5 μM for UA, 4.0 μM for EP, and15 μM for AA, in the presence of the remaining two molecules at concentrations of 50 μM for UA and EP and 600 μM for AA. We have also successfully scaled down the biosensing platform to a single carbon fiber with ZnO to demonstrate similar results. Our results indicate that the prepared biosensor was robust, highly sensitive, and stable.

Figure 1
A Non-Aqueous NaPF6-Based Electrolyte Degradation Study: Formation and Mitigation of HF
Authors: Barnes Pete , Smith Kassiopeia , White Quinn , Storch Eric , Parrish Riley , Karsann Devan , Jones Chris , Deng Changjian , Dumais Joseph , Dufek Eric J. , Xiong Claire
Published: February 2020

Water has a dynamic and significant role in the stability of NaPF6-based non-aqueous electrolytes for sodium-ion batteries. These electrolytes are highly susceptible to the formation of HF in the presence of water. Most remarkably, HF formation can be observed in battery grade electrolytes which contain <20 ppm H2O. Fundamental electrolyte characterization is important as electrolyte has a critical role in batteries’ stability and performance. In this work, we studied the degradation mechanism of NaPF6-based electrolytes with different solvent mixtures (cyclic and acyclic carbonates and varying amounts of water or HF). NMR spectroscopy reveals the electrolyte degradation in these various conditions. In addition, we have conducted fundamental studies on the stability of the sodium-based electrolytes in the presence of a phosphazene-based (FM2) or fluorinated carbonate (FEC) additive. In these systems, additives offer a way to alter the degradation rate and byproducts. Our results indicate that the phosphazene additive acts as a “HF scavenger” in electrolytes containing water. The effects on degradation mitigation can be demonstrated through the electrochemical performance of a NaNi0.4Fe0.2Mn0.4O2 (NFM)/hard carbon full cell in electrolytes containing FM2 and up to 100 ppm additional water. Without the FM2 additive, the ability of the cell to hold capacity decreased from 91 ± 0.5 mAh/g to 14 ± 2 mAh/g. Remarkably, when FM2 is present in the electrolytes which contain the same concentration of water the discharge capacity was maintained at 44 ± 3 mAh/g at a rate of 15 mA/g. The result suggests that the byproducts of the degradation were detrimental to the battery performance. Through this work, a link can be drawn between the degradation NaPF6-based non-aqueous electrolytes, the purity of the electrolytes as well as additive effect.
Synthesis of Mesoporous Carbon Using Waste Orange Peel As an Anode Material for Potassium-Ion Batteries with Long Cyclability
Authors: Verma Rakesh , Park Chan-Jin
Published: February 2020

Potassium‐ion batteries (PIBs) have been considered as the most promising candidate due to their low cost and high safety to replace the Li-ion batteries. However, current graphite anode cannot encounter the demands for high storage capacity and low cost, which are required for the commercial PIBs. Thus, it is needed to discover porous carbon anode material with high capacity, longer cycle life, low cost, and environment friendless for PIBs. Porous carbon is regarded as an attractive anode material for PIBs due to its high conductivity, chemical stability, and expanded interlayer spacing, which can helpful to accommodate more K-ions. In particular, biomass derived porous carbon has the advantages as a renewable and low cost carbon source. It can also provide excellent 3-D porous nanostructure for high storage capacity and long cyclability in batteries. Among the biomass wastes, 15.6 million tons of orange peel is discarded every year. It may be very useful if we can use these wastes as a resource for an electrode of batteries. Orange peel is mainly composed of cellulose, hemicellulose, lignin, and pectin, which are known as excellent carbon precursors.

In this study, we fabricated mesoporous carbon from orange peel through a facile one step carbonization approach without introducing extra activation agents. The mesoporous carbon displayed the first discharge and charge capacities of 408 and 224 mAh g-1, respectively, corresponding to a Coulombic efficiency of 55%. Even after 100 cycles, the electrode maintained a high capacity 210 mA g-1. When the specific current is further increased to 200 mA g-1, the high specific capacity of 150 mA g-1 was still achieved, which corresponds to a capacity retention of 80% after 2000 cycles. This superior cycling stability is attributed to the improved ionic diffusion kinetics and electronic conductivity resulting from the mesoporous structure and large interlayer spacing. Furthermore, a full cell composed of mesoporous carbon anode and potassium Prussian blue cathode displayed an adequate electrochemical performance.
Single Lithium-Ion Conducting Covalent Organic Frameworks
Authors: Park Sodam , Jeong Kihun , Lee Sang-Young
Published: February 2020

The demands for high-energy density power sources are growing from the beginning on the advent of portable devices. Since the beginning, liquid electrolyte was adopted owing to their high ionic conductivity, excellent wetting to electrode components. However, liquid electrolyte contains risks since it exhibits highly flammable and sometimes explosive characteristics. To resolve safety issue for demanded high-energy density batteries, all-solid-state battery, which utilizes solid electrolyte instead of liquid electrolyte, hold particular promise as solid-state electrolytes feature low flammability and highly compaction nature for high-energy density battery performance.

So far, all-solid-state batteries have generally been powered using inorganic sulfides/oxides or polymer-based electrolyte. In addition to these conventional approaches, solid-state Li-ion conductors based on porous crystalline materials (i. e. covalent organic frameworks (COFs) and metal–organic frameworks (MOFs)) have garnered attention due to their directional ion conduction pathways through the ordered pores and versatile structural design. Porous crystalline materials, however, additionally incorporate lithium salts and/or solvents inside the pores of frameworks so that these COFs or MOFs act as conducting medium, not solid-state ion conductors in specific. Herein, we demonstrate a lithium sulfonated covalent organic framework (denoted as TpPa-SO3Li) as a solvent-free, single lithium-ion conductors. Benefiting from the well-designed directional ion channels, high number density of lithium-ions, and covalently tethered anion groups, TpPa-SO3Li exhibits an ionic conductivity of 2.7 × 10–5 S cm–1 with a lithium-ion transference number of 0.9 at room temperature, and an activation energy of 0.18 eV. Moreover, unusual ion transport phenomena of TpPa-SO3Li allow reversible and stable lithium plating/stripping on lithium metal electrodes. These features show promising results to be adopted in next-generation all-solid-state batteries and also demonstrate potential usage for lithium metal batteries.
Li7La3Zr2O12-PEO Composite Electrolytes and the Role of Interface Resistance
Authors: Langer Frederieke , Bardenhagen Ingo , Brogioli Doriano , Schwenzel Julian , Kun Robert , La Mantia Fabio
Published: February 2020

Composite electrolytes consisting of both polymer and ceramic solid state electrolytes have recently received more attention because of their potential to combine high ionic conductivity, facile interface formation and simplified processing compared to conventional ceramic processing routes.

Ceramics (e.g. Li7La3Zr2O12 (LLZO)) show high ionic conductivity, but processing the materials into thin membranes is challenging. Energy consuming sintering steps are necessary to obtain dense specimen. In addition, ceramics are brittle, posing further challenges on subsequent processing steps. Polymer electrolytes (e.g. based on poly(ethylene oxide) (PEO)) are facile to prepare by tape casting method and offer flexibility; however, ionic conductivities are lower compared to inorganic materials. Hence, combining both materials forming a composite electrolyte may be a solution.

Here, we present the preparation of composite electrolytes consisting of LLZO and PEO based polymer electrolyte with high weight fractions of LLZO. The composites are investigated with regard to their electrochemical properties, paying special attention to the interface between ceramic and polymer. A model system is used to determine the interface resistance between LLZO and PEO as a function polymer electrolyte composition using both experimental and computational methods.
Lithium Dendrite Growth in All-Solid-State Batteries Based on Li-Argyrodite Li6PS5cl
Authors: Schlenker Ruth , Stępień Dominik , Koch Pascal , Hupfer Thomas , Indris Sylvio , Ehrenberg Helmut
Published: February 2020

In the recent years, all-solid-state batteries have attracted much attention as they are safer in terms of flammability compared to liquid electrolyte systems. There are polymer, oxidic, and sulfidic solid electrolytes with advantages and disadvantages. One major advantage of sulfidic electrolytes is their high ionic conductivity at room temperature which is even comparable with that of liquid electrolytes. Another feature is the possible usability of lithium anodes in this system which leads to very high energy density. One major challenge of the lithium metal anode is the formation and growth of lithium dendrites which results in short circuits. A lot of research is done to prevent dendrite growth but more research is needed to understand the actual dendrite growth mechanism [1].

In our work we analyzed the reasons for increase of overpotentials that is very likely related to lithium dendrite growth in symmetric lithium metal cells with solid electrolyte Li6PS5Cl. In a three-electrode set up, the interface of a lithium symmetric cell is analyzed during stripping and plating with electrochemical impedance spectroscopy. The changes of the resistance contributions are discussed in terms of possible major mechanisms that are involved in lithium dendrite growth. Furthermore, the plating behavior of lithium is investigated which gives insight into possible onset for lithium dendrite growth.

Reference
s
:

[1] Xin-Bing Cheng, Rui Zhang, Chen-Zi Zhao, and Qiang Zhang, Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review, Chem. Rev. 2017, 117, 10403−10473.
Tinplate Corrosion Under a BPA-NI Polyester Lacquer
Authors: Si Yongchao
Published: February 2020

Bisphenol A-Non Intent (BPA-NI) lacquers such as polyester and acrylics are replacing the epoxy-phenolic lacquer in the sanitary food cans. Occasional lacquer failures have been reported on cans using the BPA-NI lacquer, but the root cause of the failure was not fully understood. In this study, the corrosion behavior of the tinplate coated with a polyester lacquer was examined in three different environments to understand the corrosion mechanism under the lacquer. The study suggests a different corrosion mechanism for the lacquered tinplate and plain tinplate. Under the lacquer coating, tinplate corrosion starts with detinning to expose FeSn2 alloy layer, which is followed by iron corrosion in the pores of the alloy layer where the steel substrate is exposed. The corrosion rate of the tinplate under the lacquer can be influenced by the severity of the environment, Sn coating weights and surface cleanliness of the tinplate.
Fast Lithium-Ion Conduction Solid State-Electrolytes
Authors: Allen Jan L , Wolfenstine Jeff
Published: February 2020

Interest in solid-state electrolytes has grown rapidly in recent years owing to the desire to utilize lithium metal anode for improved specific energy density and the inherent safety advantage of a non-flammable solid state electrolyte. A practical solid electrolyte for energy storage must be a fast ion conductor, have negligible electronic conductivity and adequate chemical and electrochemical stability with electrodes. For ease of manufacturing and potentially higher power capability we have focused research on oxide ceramic electrolytes. This work will cover our work on NASICON, perovskite, garnet and other potential structural families including how to stabilize the most conductive phase and maximize the ionic conductivity through substitutional chemistry. Our main focus on garnet will include how to understand important mechanical properties, the air and moisture stability and stability with cathode materials, improvement of critical current density and future challenges and opportunities for garnet based fast lithium ion electrolytes and potential new materials.
New Electrolyte for Li Metal Batteries with High Voltage NMC811 Electrode
Authors: Cao Xia , Ren Xiaodi , Lee Houngkyung , Niu Chaojiang , Liu Jun , Xu Wu , Zhang Ji-guang
Published: February 2020

Li metal batteries (LMBs) have been revived as promising rechargeable battery chemistry in the last few years due to their high potential energy densities. However, there is still a long way to go for commercialization of LMBs because of the limited cycle life and potential safety concerns of LMBs, which are caused by the formation of high surface (porous) Li and low Coulombic efficiency (CE) during repeated charge/discharge processes. Developing advanced electrolytes is crucial to develop practical LMBs with high energy density. In this work, we report a promising electrolyte approach based on the use of a new electrolyte solvent, which can be worked as the diluent for high concentrated electrolyte (HCE) to get a localized high concentrated electrolyte (LHCE). Although with an apparent salt concentration of 1M, this electrolyte generates salt decomposition dominant solid electrolyte interphases (SEIs) on Li metal anode, which is robust and conductive. Therefore, it shows high Li Coulombic efficiency and great stability in Li||NMC811 cells. The details together with post-cycling analysis will be discussed at the presentation.