bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrothermal Synthesis, Structural Transformations and Electrochemistry of Lithium Vanadyl Phosphates
Authors: Chung Youngmin , Huang Yiqing , Chernova Natasha A. , Whittingham M. Stanley , Wiaderek Kamila M , Chapman Karena W 
Published: February 2020

The polymorph of lithium vanadyl phosphate ε-LiVOPO4 is a promising multi-electron intercalation cathode material for Li ion batteries with theoretical capacity of 330 mAh/g. It has been shown to reversibly intercalate and deintercalate Li ions over two redox potentials corresponding to V3+/4+ and V4+/5+ oxidation states. Here we report a low-temperature (LT) hydrothermal synthesis method that produces pure LiVOPO4·2H2O between 120 and 160 oC and pure ε-LiVOPO4 between 180 and 220 oC. We also investigate the structure, electrochemical and thermal properties of the products focusing on ε-LiVOPO4. X-ray diffraction indicates that the lattice parameters of LT ε-LiVOPO4 change linearly with synthesis temperature increase, approaching those reported for high-temperature (HT) synthesized ε-LiVOPO4. Thermogravimetric analysis with mass-spectroscopy (TGA-MS) indicates water loss at 350 °C decreasing from 1.5 to 0.5 wt.% as the synthesis temperature increases from 180 to 220 °C. We have interpreted these observations as an evidence of proton intercalation into the LT ε-LiVOPO4 structure. We have further investigated the process of water loss by in-situ XRD and x-ray absorption spectroscopy (XAS) upon heating, combined with pair-distribution function analysis (PDF) and magnetic measurements of LT ε-LiVOPO4 heated to 350 and 750 °C. In-situ XRD shows abrupt change in the lattice parameters dependences upon temperature at 350 °C. Ex-situ studies indicate that the structure and properties of LT samples heated to 750 °C resemble those synthesized by the solid state method at 750 °C. Interesting reversible change of lattice symmetry upon heating to 550 °C was observed and will be further discussed. LT ε-LiVOPO4 has large particle size, over 10 μm, therefore high-energy ball-milling with carbon is required to bring the particle size to below 1 μm to achieve good electrochemistry. Ball-milled product shows high initial capacity around 300 mAh/g, which holds for about 10 cycles and then gradually decays. The voltage profile of LT ε-LiVOPO4 is sloping upon delithiation, in contrast with the step-like profile of HT ε-LiVOPO4. The detailed distinctions between LT and HT ε-LiVOPO4 leading to variations in the electrochemical performance will be discussed. This work was supported as part of the North East Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012583.
Morphological Effect on Nano and Micro Dimensional CuO As Anode Material for Li-Ion Batteries
Authors: Subalakshmi P , Sivashanmugam A 
Published: February 2020

Transition metal oxides (TMO) with commendable theoretical capacity resulted from the conversion reaction have been studied extensively as anode material for Li-ion batteries. The major limitations of TMO are low electrical conductivity and large volume change about 174 % during cycling reaction. This can be overcome by modifying the morphology of the active material. Different morphological nano and micro structures have been synthesized by various synthetic procedures. CuO, a prominent TMO, has been explored by many researchers due to its high theoretical capacity, less toxicity and easy availability.
In the current investigation, different morphological CuO have been synthesized by rapid hydrothermal and precipitation method. Physical characterizations are carried out viz., XRD, FESEM, TEM, FT-IR, and XPS techniques. Electrochemical cycling performance of the synthesized CuO of different morphologies have been evaluated as anode material for Li-ion batteries at different current densities between 215 mA g-
1 and 4.3 A g-
1. CuO of nano hexagonal morphology obtained from hydrothermal synthesis exhibits stable discharge performance of ~575 mAh g-
1 at current density of 215 mA g-
1 with low irreversible capacity of 265 mAh g-
1 in the first cycle. This resultant value is comparably lower than several reported values obtained from different nano morphological CuO and composites of CuO with conducting additives, establishing it as a superoir anode material for lithium ion batteries. Nano CuO anode exhibits high rate capability up to the current density of 4.3 A g-
1
, resumes the initial capacity of 572 mAh g-
1 even after 100 cycles and remains stable with zero capacity fading at 215 mA g-
1 current density. While CuO microballs synthesized via precipitation method delivers charge and discharge capacity of 860 mAh g-1 and 372 mAh g-1 during first cycle respectively at the current density of 215 mA g-
1. Further, the capacity fading increases upon cycling and delivers 276 mAh g-1 after 30 cycle. Ex-situ FESEM analysis clearly inidicates that the morphology change during lithiation and delithiation reaction is responsible for the varying cycling performance. CuO nano hexagons form an integrated network thereby enhancing the electrical conductivity for better electrochemical performance. In the case of CuO microballs, the disconnected microstructure formed during cycling due to the volume change causes electrode disintegration and poor electrochemical performance at higher current rate.
Investigation of the Effects of Formulation, Slurry Preparation and Coating Conditions on the Mechanical Properties and Electrochemistry of Carbon-Based Lithium-Ion Battery Electrodes
Authors: Lanz Patrick 
Published: February 2020

Typically, new electrode materials for lithium-ion batteries are first tested on the laboratory-scale. Although this generally gives a good indication of the electrochemical performance of the active materials (e.g. specific charge and potential profile), it does not paint the whole picture: Electrode materials that look promising on the laboratory-scale might not necessarily turn out to be suitable for industrial applications, and vice versa. In particular, the upscaling to industrial quantities might pose significant challenges related to various processing issues (e.g. mixing, rheology and coatability). Therefore, it is essential to follow up on laboratory-scale experiments with larger-scale coating tests.
We investigated various formulations containing synthetic graphite negative electrode material (IMERYS Graphite & Carbon) and tested the electrochemical performance of the resulting electrodes. Instead of applying the common laboratory-scale doctor blading process, the slurry was cast onto copper foil using the technically relevant comma-bar method on an industrial coating line. We investigated the effects of various parameters, such as formulation and preparation of the aqueous slurry (e.g. mixing conditions), binder and electrode additives, as well as coating conditions (e.g. continuous/intermittent and unpressed/pressed) on the homogeneity (e.g. thickness, mass and density distribution), adhesion (peeling strength) and electrochemistry (cycling behavior) of the resulting electrodes.
The experiments showed that the solid content and the mixing conditions as well as the coating mode (continuous/intermittent) and calendering process (unpressed/pressed) have a significant influence on the properties of the final electrodes. A higher solid content generally resulted in more homogeneous electrodes due to less sagging (gravity induced flow). Increased shear rates and mixing times, on the other hand, led to better electrochemical properties due to a more effective dispersion process. Furthermore, continuous coating allowed the preparation of more homogeneous electrodes than intermittent coating. Finally, calendering (which, of course, reduces the electrode thickness and increases the electrode density) resulted in improved adhesion and a more homogeneous thickness distribution, while negatively affecting the density distribution.
The methodology offers a useful way of further evaluating active material candidates that have been shown to be promising in laboratory-scale electrochemical experiments with regard to the electrode engineering and manufacturing on the pilot-scale and thus provides important information for the development of electrode materials.
Long Duration Studies of Li-Ion Battery Materials Using Synchrotron X-Ray Powder Diffration
Authors: Day Sarah , Baker Annabelle , Tang Chiu C. 
Published: February 2020

The Long Duration Experiment (LDE) Facility on Beamline I11 at Diamond Light Source is the first of its kind, allowing in situ synchrotron X-ray powder diffraction (SXPD) data to be collected on a weekly basis for extended periods of time (a few months up to a few years). The facility is capable of housing multiple experiments simultaneously, and even though data are only collected at weekly intervals the experiments remain in place and all sample environments (high/low temperature, humidity, electrochemical cycling) are maintained throughout the duration of the experiment.
The increasing demand for large-scale energy storage (e.g. electric vehicles) means that new materials, with much higher Li+ storage capabilities and longer lifetimes than are currently available are required to meet this demand. Many promising candidates for such materials are known but before these can become commercially available their chemical/structural stability and electrochemical cycling performance need to be well understood. In-situ powder diffraction has proven to be an extremely useful technique for just this, providing an insight into the complex chemical process that take place during charge/discharge cycling. Standard in situ experiments using existing facilities are, however, often limited to short periods of time, from a few hours up to a few (2-3) days, and therefore, only allow the first few cycles (often at accelerated charging rates) of the material to be observed. The result is that the material characteristics may be well understood for the first cycle but little is known about the long term processes that ultimately lead to failure of the cell over longer timescales.
With a specially designed coin cell holder (Figure 1 inset) and dedicated multi-channel Arbin battery cyclers it is an ideal facility for the long term study of both existing and novel battery materials. This setup allows data to be collected over many hundreds of cycles at slower, more realistic, rates without the need for accelerated cycling therefore better simulating battery use under real-life conditions. To achieve this, a new in situ cell was developed through the modification of a standard CR2032 coin cell which allows for the transmission of X-rays while retaining the integrity and impermeability of the stainless steel case and therefore allowing the cell to perform well for long periods of time.
Details of the facility and the modified coin cells will be presented along with preliminary results of the first long term battery studies, of a selection of Li-based electrodes (commercial and novel materials), to demonstrate the capabilities of this facility and the quality of the data produced.

Figure 1
Ceramic-Coated Membrane Using Aqueous Coating Solution for Lithium-Ion Battery
Authors: Im Jinsol , Lee Jieun , Kim Sang Woo , Lee Yong Min , Cho Kuk Young 
Published: February 2020

Lithium-ion battery (LIB) is now expanding its application from small-sized mobile device applications to Mid- and Large-sized applications such as energy source for electric vehicles and energy storage systems. Among the requirements for LIBs for bigger sized systems, lowering cost and improving safety is directly connected with their successful application. Recently, there is increasing interest on using aqueous process for fabricating LIB components such as electrodes and separators. Improved performances using water-soluble binders for preparing electrodes with various active materials. Removing organic solvent (NMP, DCM) can not only provide environmental-friendly process but also reduces cost for the treatment of used solvents. Here we present ceramic coated separator (CCS) that is fabricated using aqueous coating solution. Also we focus on the reducing moisture reabsorption which could be problematic issue for long storage.
Exploiting Steric Factors in the Design of New Overcharge Additives
Authors: Guarr Thomas F. , Mortimer Nicholas , Prins Amber J. , Polik Robert 
Published: February 2020

Overcharging high energy density lithium ion batteries (LIBs) can lead to rapid temperature increases, autocatalytic processes, gas evolution, and other undesirable (yet occasionally exciting) consequences. Thus, LIB pack manufacturers generally incorporate electronic controls in order to prevent overcharge conditions as well as to provide for cell balancing. Such battery management systems add significant complexity, and the inclusion of overcharge additives or “redox shuttles” in the electrolyte has been proposed as a safe and cost-effective alternative. These shuttles can provide both passive cell balancing and overcharge protection by functioning as a molecular shunt when the desired turn-on voltage is reached.
Numerous organic and inorganic compounds have been investigated as shuttle candidates, but finding materials that possess both a sufficiently high oxidation potential and adequate durability has proven extremely challenging. The ideal shuttle should be compatible with all electrolyte and cell components, have an oxidation potential near or slightly higher than the maximum cell voltage (i.e., 4.2 V vs. Li/Li+for NMC cells), and be highly stable in both reduced and oxidized forms. It should also be inexpensive, highly soluble (even at low temperature), display a reasonably large diffusion coefficient, and exhibit favorable electrode kinetics.
One common approach is to begin with a redox-active heterocyclic skeleton and add appropriate electron withdrawing substituents until the desired oxidation potential is reached. However, because of the resultant lack of electron density in the ring system, this strategy often leads to systems that are susceptible to dimerization, unimolecular decomposition, or nucleophilic attack in their oxidized form. We have developed an alternative approach that exploits the change in molecular geometry that often accompanies the oxidation of heterocyclic compounds. Specifically, by introducing bulky groups to sterically impede this reorganization, computer modeling suggests that oxidation potentials can be shifted to more positive values without sacrificing stability. Our preliminary results employing this strategy on various substituted heterocycles have borne out these predictions, as we have observed increases in both oxidation potential and chemical reversibility.
A Low-Cost, Environment-Friendly Lignin-Polyvinyl Alcohol Composite Separator Using a Water-Based Method for Safer and Faster Li-Ion Batteries
Authors: Uddin Md-Jamal , Alaboina Pankaj Kumar , Zhang Lifeng , Cho Sung-Jin 
Published: February 2020

A lignin/polyvinyl alcohol (lignin/PVA) composite membrane has been prepared as a separator for lithium-ion batteries (LIBs) using a simple, low-cost, environment-friendly, water-based method. Lignin is a low-cost, naturally occurring, widely abundant, sustainable, biodegradable, and biocompatible material. Polyvinyl alcohol (PVA) has good hydrophilicity, biocompatibility, chemical and thermal stability, mechanical strength, and abrasion resistance. PVA can serve as a host skeleton to draw fibers out of the lignin/PVA composite using a spinning method. In this work, Lignin and polyvinyl alcohol (PVA) were dissolved in water separately, and the water-based solution was mixed together to make the dope – from where the electrospun fibers were drawn to form a non-woven lignin/PVA membrane. A highly porous interpenetrating network structure resulted, which was revealed by scanning electron microscopy. Electrolyte compatibility, uptake tests, and contact angle measurements were examined with three different electrolytes focusing different anodes and supercapacitors, and they all showed favorable results. Thermal shrinkage test and thermogravimetric analysis showed high thermal stability and good flame retardant properties of the membrane. Electrochemical cycling performances were investigated comparing to commercial Celgard separator, using Li/Li(Ni1/3Mn1/3Co1/3)O2 electrodes, and they showed good results for lignin/PVA membrane. Rate performance and electrochemical impedance spectroscopy revealed high rate performance using the lignin/PVA membrane that is caused by its high ionic transport property. The lignin/PVA composite separator showed enhanced physical, thermal and electrochemical properties, and can be considered as a suitable separator for LIBs with graphite or silicon anodes, as well as for supercapacitors.
A Flame Retardant Gel Polymer Electrolyte Containing Mg(OH)2 Particles for Lithium Ion Battery
Authors: Kim Seokwoo , Jeong Jiseon , Lee Hoogil , Han Taeyeong , Jin Dahee , Ryou Myung-Hyun , Lee Yong Min 
Published: February 2020

Although lithium ion batteries (LIBs) as an energy storage device have been identified as the most promising candidate for large scale automotive and aerospace applications, safety issues still remain to be secured. Hence in order to improve the safety of LIBs, we introduce a new gel polymer electrolyte (GPE) containing the frame retardant material, magnesium hydroxide (Mg(OH)2). First, a dense polymer film of the thickness of 20 µm is prepared by casting the precursor solution consisting of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) as a polymer matrix, dibutyl phthalate (DBP) as a pore generation agent, and Mg(OH)2 as a flame retardant agent, in acetone. And then, DBP is extracted in the methanol bath to make pores in the polymer film. They are gelled with additional liquid electrolyte, 1.15M LiPF6 in ethylene carbonate/ethyl methyl carbonate (EC/EMC, 3/7 by vol).
Mg(OH)2 composited GPE exhibits a distinguished fire-retardant properties, which results in a relevant self-extinguishing time (SET) reduction. The ionic conductivity is also greatly enhanced in the GPEs with increasing ratio of Mg(OH)2. Due to the hydrophilic properties of Mg(OH)2, unit cells employing LiCoO2 cathode, the composite GPE, and graphite anode achieve significant improvements in rate capability and cycle performance that were closely associated with their improved uptake for liquid electrolyte. The electrochemical stability of the GPE with Mg(OH)2 is comparable to that without Mg(OH)2. This results imply that Mg(OH)2composited GPE can provide the large-format LIBs with greatly improved safety.

Acknowledgements

This work was supported by the Energy Technology Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20142010102980)

Refernces

1. Daeyong Yeon , Yunju Lee , Myung-Hyun Ryou , Yong Min Lee, Electrochimica Acta 157 (2015) 282-289
2. Myung-Hyun Ryou, Yong Min Lee, Jang Wook Choi, Jung-Ki Park, Electrochemistry Communications 17 (2012) 18-21
3. Yong Min Lee, Dong-Hyun Ko, Jun Young Lee, Jung-Ki Park, Electrochimica Acta 52 (2006) 1582–1587
Ionic Liquid Electrolytes for Safer Lithium Batteries: I. Investigation Around Optimal Formulation
Authors: Moreno Margherita , Simonetti Elisabetta , Appetecchi Giovanni Battista , Carewska Maria , Montanino Maria , Kim Guk-Tae , Loeffler Nicholas , Passerini Stefano 
Published: February 2020

Ionic liquids (ILs) are more and more investigated as substitutes of volatile and flammable organic electrolyte solvents in rechargeable lithium-ion battery systems [1] to enhance safety of the electrochemical device. So far, single ILs do not generally match or fully satisfy the requirements and/or operative conditions of practical devices, even if the ionic liquid properties could be finely tuned by suitably modifying their architecture [1]. A promising approach is represented by properly combining different ionic liquids, leading to beneficial synergic effects on the physicochemical properties of the resulting IL mixture [1].
In the present work, we have developed ternary mixtures by incorporating different fractions of the LiTFSI salt into the proper PYR13TFSI-PYR13FSI blend. Pyrrolidinium-based ILs were successfully proposed for lithium batteries [1]; the TFSI anion has proved to be stable toward oxidation and thermally robust [1] whereas FSI exhibits high conductivity even at low temperature coupled with protective film-forming capability onto electrodes [1].
Results and Discussions
An eco-friendly procedure route [2] allowed to synthesize high purity, anhydrous, clear, colorless and odorless ionic liquid samples with yields ranging from 85 to 90 mol.% and water content below 2 ppm.
Proper PYR13TFSI-PYR13FSI formulations have shown ion conduction approaching 10-3 S cm-1 at -20 °C whereas the pure IL materials, still in solid state, exhibit conductivity values four orders of magnitude lower. This behavior is likely due to different hindrance of the anions, resulting in worse ion packing. On the basis of the obtained results, the TFSI:FSI mole ratio was selected equal to 2:3.
The LiTFSI-PYR13TFSI-PYR13FSI mixtures (Figure 1) have exhibited high conductivity (about 10-3 S cm-1), even at low temperatures (-20 °C), in good agreement with the thermal and rheological properties. Cyclic voltammetries (Figure 2) have indicated electrochemical stability up to 5 V in conjunction with the possibility to reversibility intercalate Li+ ions into carbonaceous anodes, this also suggesting good mobility of lithium at the interface with electrodes.
Acknowledgements
The authors wish to thank the financial support of the European Commission for the GREENLION project within the 7th Framework Program (Grant agreement n°: 28526).
References
[1] G.B. Appetecchi, M. Montanino, S. Passerini, Ionic Liquid-based Electrolytes for High-Energy Lithium Batteries, in Io
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[2] M. Montanino, F. Alessandrini, S. Passerini, G.B. Appetecchi, Electrochim. Acta 96 (2013) 124

Figure 1