bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Rate Capability By Dynamic Crystal Structure Change of Co-Substituted LiFePO4 with Reduced Lattice Mismatch
Authors: Yoshinari Takahiro , Orikasa Yuki , Mori Takuya , Nishijima Motoaki , Ohira Koji , Esaki Shogo , Sueki Toshitsugu , Ootani Takuya , Kamimura Yuuichi , Ohara Koji , Fukuda Katsutoshi , Uchimoto Yoshiharu
Published: February 2020

For the practical use of Lithium-ion battery in electric vehicles, the rate capability should be more improved. Although LiFePO4 is wildly known as the high power cathode materials, the large mismatch between LiFePO4 and FePO4 might still disturb the further improvement of the rate capability. Because the huge volume change during the phase transition require the large activation energy, the suppression of the crystal structure change is one of attracted design principle for cathode materials. Recently, Nishijima et al have reported that Zr-substitution in LiFePO4 eliminates the volume change between LiFePO4 and FePO4 and the cyclability of the doped LiFePO4 is drastically improved[1]. In this study, we investigate the rate capability of the Zr-dopoed LiFePO4. Moreover the phase transition behavior is examined by using operando X-ray diffraction measurements.

LiFePO4, called hereafter undoped LFP, and Li(Fe0.95Zr0.05)(P0.9Si0.1)O4, called Zr-doped LFP, were synthesized by the solid solution method in the same manner as reported[1]. The crystal structure of the prepared samples were analyzed by X-ray diffraction (XRD) which were performed at beamline BL02B2, SPring-8 with a wavelength of 0. 699292(4) Å using a Debye-Scherrer camera and an imaging plate detector. The electrodes for the electrochemical tests were prepared by mixing 80% active material, 10% carbon black, and 10% polyvinylidene fluoride (PVDF) with 1-methyl-2-pyrrolidinone solvent. The slurry was then casted onto an Al foil current collector. 1 M LiPF6 in a 3:7 volume ratio of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used as the electrolyte. Li foil was used as a counter electrode. operando time-resolved XRD measurements were performed at SPring-8 with a wavelength of 0.619862(2) Å using a 1D detector, Mythen.

All the peaks of XRD pattern of the both prepared powder samples are indexed to orthorhombic Pnma space group and any impurity is not observed. The calculated lattice volume of Zr-doped LFP is almost similar to that of undoped LFP. SEM measurements indicate that the particle size of both undoped LFP and Zr-doped LFP is approximately 100 nm. The rate capability of Zr-doped LFP is improved compared with undoped LFP. At 10 C rate, 110 mAh/g is still acquired in Zr-doped LFP, while the capacity of undoped LFP is decreased to 90 mAh/g. The polarization of the discharge profile is also suppressed by Zr substitution. Operando time-resolved XRD measurements reveal that the expansion of solid solution reaction of LiFePO4 and FePO4end-members in nonequilibrium condition.

REFERENCES

[1]  Nishijima, M.; Ootani, T.; Kamimura, Y.; Sueki, T.; Esaki, S.; Murai, S.; Fujita, K.; Tanaka, K.; Ohira, K.; Koyama, Y.; Tanaka, I., Nat. Commun.
5, 4553 (2014).
Probing the Aging Effects on Nanomechanical Properties of a Thin Film LiFePO4 Cathode
Authors: Demirocak Dervis Emre , Bhushan Bharat
Published: February 2020

Despite widespread usage of Li-ion batteries in portable electronics, large scale utilization of Li-ion batteries in electric vehicles and grid-level energy storage is only possible if cost, safety, energy density, specific power and cycle life of Li-ion batteries are further improved. Enhancing the cycle life is especially critical for wider market penetration of Li-ion batteries which requires detailed understanding of the degradation mechanisms. The interplay between various battery subcomponents such as cathode, anode, separator, electrolyte and current collector determines the degradation mechanisms of Li-ion batteries that can have both chemical and mechanical origins that are closely interrelated. Chemical degradation mechanisms such as solid electrolyte interphase formation and electrolyte decomposition have been studied extensively; however, mechanical degradation mechanisms attracted less attention. Mechanical degradation is associated with the volume changes and stress generated during Li de-/intercalation in an active material which can result in formation of cracks, delamination and isolation of the active particles causing capacity and power losses.

Our previous work on composite LiFePO4 cathode by nanoindentation revealed that elastic modulus deteriorates by aging as well as shows spatial variation on the electrode surface [1]. Binder is the compliant component in a composite electrode; therefore, degradation in elastic modulus is associated with the binder not the active material. To determine the mechanical degradation in the active material, thin film LiFePO4 cathode (i.e., no binder or carbon coating/additive as in a composite electrode) was synthesized by physical vapor deposition, and employed in determining the changes in the mechanical properties of the active material due to aging. The preliminary AFM experiments on thin film LiFePO4 cathode showed significant changes in particle morphology and roughness upon cycling as shown in Fig. 1. On the other hand, mechanical properties of the thin film LiFePO4 did not show as significant deterioration as in a composite LiFePO4 cathode indicating mechanical degradation in binder is more problematic than the mechanical degradation in the active material.  

References

[1] Demirocak, D.E., Bharat B., Probing the aging effects on nanomechanical properties of a LiFePO4 cathode in a large format prismatic cell, Journal of Power Sources, 2015, 280, 256-262.

Figure 1
Degradation Analysis of Commercial Lithium-Ion Batteries Using Voltage Curves and Thermal Behaviors
Authors: Kato Hisashi , Kobayashi Takeshi , Shono Kumi , Ohno Yasutaka , Kobayashi Yo , Miyashiro Hajime , Mita Yuichi
Published: February 2020

Introduction

 Large scale Lithium-ion batteries are starting to be installed in the world to stabilize the voltage and frequency because variable powers such as photovoltaic and wind powers are installed for the electrical power systems. Life-time estimation is very important for maintenance of batteries and degradation analysis is developed to contribute to this estimation.

 We have developed the degradation analysis of small size cells by using cell disassembly and reproduction of cells [1, 2]. Misalignment of the operational area of the positive and negative electrodes in the cell due to the lithium irreversible consumption at the anode mainly occurred in the degrade cells.

 In this study, we investigate the degradation behavior of large size lithium-ion batteries with several ten Ah.

Experimental

 30Ah class commercial cells were tested in this study. Galvanostatically cycle test were performed in the 10-90% SOC range during charge and discharge at 25, 35 and 45 degC. The other cells were charged up to 50%, 70% and 100% SOC at 25 degC and stored at 25, 35 and 45 degC. The test intervals are 80 and 120 cycle at cycle test and 15 and 20 days at storage one. Capacity test were performed in C/20 rate at 25degC among the cycle and starage test period. Temperature test was conducted using the original thermal insulator. Postmortem analysis were performed at cycled and SOC 50% aged sells at 45degC. These cells were disassembled in an Ar globe box and reassembled to coin cells. Capacity tests were performed in C/20 rate with half-cells and “Nico-ichi” cell with quasi-reference electrode.

Results and Discussion

 The cells were analyzed by the results of the differential voltage versus capacity, dV/dQ vs. Q analysis using “Nico-ichi” coin cell and temperature measurement during charge and discharge using a quasi-adiabatic cell folder. It was observed that dV/dQ peaks and temperature peaks shifted with decreasing cell capacity as shown in Fig.1. The analysis of peak shifts has potentials to the non-destructive prediction of the cell life.

References

1. Y. Kobayashi, T. Kobayashi, K. Shono, Y. Ohno, Y. Mita and H. Miyashiro, J. Electrochem. Soc., 160 (2013) A1181 – A1186.

2. K. Shono, T. Kobayashi, M. Tabuchi, Y. Ohno, H. Miyashiro and Y. Kobayashi, J. Power Sources, 247 (2014) 1026 – 1032.

Figure 1
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.
Si@Co2SiO4/Reduced Graphene Oxide Nanocomposite Anodes for High Performance Lithium Ion Batteries
Authors: Park A Reum , Yoo Pil J.
Published: February 2020

Silicon (Si) has regarded as one of the most promising anode materials for next-generation Li-ion batteries (LIBs) because of its high theoretical capacity (4200 mAh/g), which is over 10 times higher than that of conventional graphite anodes (372 mAh/g). However, Si anode suffers from drastic volume expansion (~300%) upon Li alloying/dealloying, resulting in the structural collapse of the electrode. Therefore, Si anode loses electrical contacts with current collector and among the anode structures leading in rapid capacity fading. To overcome these obstacles, metal silicates (e.g. Co2SiO4, Zn2SiO4, Fe2SiO4, and Mn2SiO4) have been considered as good additive to suppress the structural changes and maintain electrochemical performance of Si anodes. In this study, Si@Co2SiO4/reduced graphene oxide (rGO) ternary nanocomposite was prepared by mixing Si nanoparticles, cobalt nitrate, and GO nanosheets, followed by hydrothermal treatment to create the Si@Co2SiO4 core-shells wrapped with multilayered rGO nanosheets. In particular, Co2SiO4 hollow structures of the composite enlarged the contact area of the electrode with electrolyte thereby facilitating fast transportation of electrons and Li ions during cycling. Moreover, void spaces between the Si@Co2SiO4 accommodated the huge volume change of Si during cycling. Furthermore, rGO nanosheets uniformly surrounding the core-shells enhanced the specific capacity and cycling stability of the anodes due to their good structural flexibility and electrical conductivity. As a result, the Si@Co2SiO4/rGO ternary nanocomposite achieved the significantly improved reversible capacity, steady cycleability, and excellent rate capability. We expect that this ternary system would further be extended to other nanocomposites as high-performance anode materials for next-generation LIBs.
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.
Safety Technology for Li-Ion Batteries
Authors: Lo Jen Chih , Chen Chen Chung , Hsu Jung Mu , Yang Chang Rung , Wu Hung-Chun , Pan Jing Pin
Published: February 2020

All commercial Li-ion batteries are prone to explode if short-circuited, particularly internally. Internal short-circuit is possible due to impurity contamination during the process of battery manufacture. Most battery accidents capturing media attention are of this nature. Or, as a result of battery structural failure because of puncture or impact in an accident for example, a Li-ion battery also explodes. Basic design idea in commercial batteries for the prevention of such internal short circuit-induced thermal runaway or explosion relies on the insertion of a separator between cathode and anode electrodes inside the battery. This separator is good enough for normal conditions of battery use but not more. When subjected to severe impact or even penetration in an accident, this separator is virtually useless in withholding the drastic explosive battery energy release. The desire by the consumer for a non-exploding Li-ion battery is most obvious. To enhance the safety level a new generation cell which adopts STOBA is currently under development. STOBA, the abbreviation of self terminated oligomer of hyper-branched architecture is proved to be an effective solution to prevent cell thermal runaway from internal short. Or explode if short-circuited, particularly internally. Internal short-circuit is possible due to impurity contamination during the process of battery manufacture. Most battery accidents capturing media attention are of this nature. Or, as a result of battery structural failure because of puncture or impact in an accident for example, a Li-ion battery also explodes.

Figure 1
Study on the Lithium Plating and Dissolution Behavior on Anode of Lithium Ion Battery
Authors: Qian Kun , Li Yiyang , Luo Dan , Li Baohua , Liu Dongqing , He Yan-bing , Kang Feiyu
Published: February 2020

Lithium batteries are successfully employed in consumer electronics and gradually accepted as the power sources of electrical vehicles, however, safety issues caused by lithium plating on anodes still exist and limit their application in the low-temperature environments such as winter days or aerospace. After low-temperature cycling tests, serious lithium plating and capacity decay were observed on soft-packed Li(Ni1/3Co1/3Mn1/3)O2/graphite (NCM/C) batteries. Even so, 15~20% of the capacity loss is reversible at room-temperature indicating that the deposited lithium on anode could transform into cyclable lithium again. The lithium plating and dissolution were characterized by scanning electron microscopy (SEM), inductive coupled plasma emission spectrometer (ICP), Raman spectroscopy and electrochemical tests. Post recovery operations, such as rest or cycling at different temperatures and rates, were tried and the corresponding reversible degree of lithium is presented in detail. Promising recovery methods were prompted to increase the degree of reversible lithium, capacity retrieval, and operation safety.
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
Application of Phase Change Materials for the Safety and Thermal Management of the Lithium-Ion Batteries at High Temperature Climate Conditions
Authors: Sadrameli Seyed Mojtaba , Azizi Yazdan
Published: February 2020

A composite of a phase change material and aluminum sheets has been used for the thermal management system of LiFePO4 pack to control the temperature rise of the batteries at high temperature regions (50-55 oC). Poly Ethylene Glycol 1000 (PEG1000) with melting point of 35-40 oC has been selected as a phase change material. Aluminum sheets have been applied to the PCM for thermal conductivity enhancement and also to improve the temperature uniformity of the system. Preliminary experimental runs have been performed in charge and discharge of the batteries at different rates of 1C to 3C to obtain the maximum surface temperature of the batteries. A mathematical model has been developed in COMSOL ver. 5.1 and the results of the model have been verified by the experimental data obtained at different conditions. The experimental data has been compared The results show that using the PCM and aluminum sheets between the cells can reduce the surface temperature significantly and causes better performance and temperature uniformity of the battery pack. The maximum cells surface temperatures at ambient temperature condition have been reduced by 19%, 21%, and 26% for the rates of 1C, 2C, and 3C respectively.
UV-Curable Solid Polymer Electrolytes Based on Poly(ethylene glycol) and Cardanol Moiety for All-Solid-State Lithium Secondary Batteries
Authors: Baik Ji-Hoon , Kim Dong-Gyun , Shim Jimin , Lee Jin Hong , Choi Yong-Seok , Lee Jong-Chan
Published: February 2020

Solid polymer electrolytes based on poly(ethylene glycol) and cardanol, a renewable resource from cashew nut shell liquid, were prepared and their properties were investigated. UV-induced self-crosslinkable polymer matrix were synthesized by free radical copolymerization of poly(ethylene glycol) methyl ether methacrylate and 2-hydroxy-3-cardanylpropyl methacrylate. Solid polymer electrolytes were prepared by simple solution casting method followed by UV irradiation, which induces cross-linking reaction of cardanol moieties. The obtained electrolytes were dimensionally stable, free-standing, and thermally stable. Maximum ionic conductivities of 2.6 X 10-5 S/cm at 30 oC and 2.5 X 10-4 S/cm at 60 oC were obtained when cardanol content in the matrix polymer was 8 mol% and lithium salt doping concentration ([Li+]/[EO unit]) was 0.05. The feasibility of the prepared electrolytes to solid polymer electrolytes for lithium secondary batteries was examined by linear sweep voltammetry and galvanostatic charge-discharge cell test.

Figure 1
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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s, ACS Symposium Series1117, A.E. Visser, N.J. Bridges and R.D. Rogers editors, Oxford University Press, Inc., American Chemical Society, Washington, DC, USA.

[2] M. Montanino, F. Alessandrini, S. Passerini, G.B. Appetecchi, Electrochim. Acta 96 (2013) 124

Figure 1
Field Assisted Sintering of Li7-3xLa3Zr2AlxO12 Solid Electrolyte and the Influence of the Microstructure on the Electrochemical Performance
Authors: Botros Miriam , Djenadic Ruzica , Hahn Horst
Published: February 2020

To enable large-scale applications of lithium ion batteries for transportation and storage of renewable energy high energy densities, high power, reduced costs and, most importantly, safety are required. The use of liquid organic electrolytes that exhibit high vapor pressures and flammability poses a substantial safety issue in particular for large-scale systems. Solid electrolytes offer a potential solution due to their inherent chemical stability. Recently, several material systems such as Li7-3x
La3Zr2Al
x
O12 (LLZO) have been identified that exhibit a large electrochemical window, ionic conductivities similar to those of liquid electrolytes at moderate temperatures and are stable against lithium metal, paving the way to the integration in high energy density battery cells.

In this work the synthesis and processing of fine-grained Li7-3x
La3Zr2Al
x
O12 solid electrolyte is performed for the first time using a combination of nebulized spray pyrolysis (NSP) and field assisted sintering technique (FAST). The microstructure, i.e. grain size and microstrain, has a crucial influence on the electrochemical properties of the solid electrolyte and thereby on the all-solid-state battery performance. During sintering using FAST, the grain growth is suppressed and dense ceramics with 93 % of the theoretical density are obtained. The microstructure and the phase composition are characterized using scanning electron microscopy and X-ray diffraction, respectively. The total lithium ion conductivity of the solid electrolyte at room temperature is found to be in the order of 10-4 Scm-1, which is in very good agreement with the literature values. The total conductivity is determined in a wide temperature range from 220 K to 393 K for the determination of the activation energy. Galvanostatic cycling of symmetrical cells using lithium electrodes shows a good cycling stability over 100 hours. The interfacial resistance in contact with lithium metal is determined using alternating current impedance spectroscopy and is amongst the best reported values so far. Several techniques for the integration of Li7-3x
La3Zr2Al
x
O12 solid electrolyte in an all-solid-state battery are presented and discussed.
Solid State Electrolytes Based on Doped Li7La3Zr2O12 Garnets: Crystal Chemistry, Ion Transport and Implementation into Li Batteries
Authors: Llordés Anna , Buannic Lucienne , Manalastas William Wang , Aguesse Frédéric , López del Amo Juan Miguel , Carrasco Javier , Kilner John A.
Published: February 2020

Solid-state batteries could greatly boost current Li-ion technologies; they are expected to endure tens of thousands recharges, pack 2-3 times more energy as well as being safe from combustion and non-toxic. However, a widespread application of solid-state batteries is still far from being achieved owing mainly to limitations of the solid electrolyte component. Key challenges are achieving high ionic conductivity-in the range of 1 mS/cm-, good interfacial contact with the electrodes and easy/cost efficient processing. Among ceramic electrolytes, the garnet family Li7La3Zr2O12 (LLZO) is one of the most promising because of its high lattice conductivity for Li ion and its wide electrochemical stability [1],[2]. Unfortunately, these garnet-type materials often show highly resistive grain boundaries and have proven difficult to process into dense ceramic bodies.

In this presentation I will show our research on developing high-performance LLZO solid electrolytes. By using a wide variety of techniques, such as solid-state NMR, XRD, SEM and EIS, as well as DFT simulations, we investigate the role of crystal chemistry, doping and processing to the total conductivity and sintering properties of the ceramic electrolyte. I will particularly focus on the fundamental understanding and enhancementof ionic conductivity via substitutional doping of Li+ by Ga3+, which led to values as high as 1.3 mS/cm for Li6.55Ga0.15La3Zr2O12 at room temperature[3]. Alternative substitutions on the Zr4+ site can lead to a wider range of compositional possibilities and even higher conductivity values. The implementation of these LLZO garnet electrolytes into full cell devices, with LFP or LCO as cathode and Li metal as anode, will be also presented.

Finally I will report on a novel solid electrolyte concept based on the combination of doped LLZO garnets and polymeric Li-ion conductors, such as polyethylene oxide (PEO). These ceramic-polymeric composites show great promise as solid electrolyte membranes given the superior mechanical and interfacial properties compared to pure ceramics.

[1] R. Murugan, V. Thangadurai, W. Weppner. Angew. Chem. Int. Ed. 46, 7778-7781 (2007).

[2] M. Nakayama, M. Kotobuki, H. Munakata, M. Nogamia and K. Kanamura. Phys. Chem. Chem. Phys., 14, 10008-10014 (2012).

[3] Bernuy-Lopez, C.; Manalastas, Jr. W.; Lopez del Amo, J-M.; Aguadero, A.; Aguesse, F.; Kilner, J. A. Chemistry of Materials, 26, 3610 (2014).
Ceramic Polymer Hybrid Electrolyte Based on Li7La3Zr2O12 for Solid-State Batteries
Authors: Langer Frederieke , Glenneberg Jens , Bardenhagen Ingo , Kun Robert
Published: February 2020

Solid-state lithium-ion batteries are a promising type of batteries for future applications. While replacing flammable liquid electrolytes with solid alternatives gives advantage to improved safety, the higher density of these solids compared to the currently used liquids is detrimental to the gravimetric energy density. Therefore, for sufficient battery cell performance thin and dense electrolyte layers of highly Li+ conductive material are needed. Currently, materials investigated for solid electrolyte application include ceramics, glasses and polymers.

Ceramic Li7La3Zr2O12 (LLZO) with cubic garnet like crystal structure has emerged as one of the most promising materials as electrolyte. Its advantages include high Li+ conductivity and chemical stability vs. lithium metal anodes. The material can be synthesised by solid state reactions as well as various wet chemistry routes. The product usually obtained from all methods is a powder. Processing this powder into a thin electrolyte layer that is suitable for battery production proofs to be difficult. Physical vapour deposition methods (e.g. pulsed laser deposition or sputtering) have been used to create thin film layers of LLZO, but these methods are limited and not suitable for large scale production. Easier processing techniques (e.g. tape casting and extrusion) are found for solid polymer electrolytes, but so far ionic conductivities of solid polymer electrolytes fall short of ceramic and glass electrolytes.

The objective of this study is to combine the advantages of ceramic and polymer electrolytes by fabrication of a hybrid solid state electrolyte. The hybrid mainly consists of LLZO and employs a polymer electrolyte as a binder. The aim is to produce a hybrid electrolyte for easier processing of solid-state batteries. Therefore, LLZO powder obtained from a facile wet chemistry synthesis route is mixed with solid polymer electrolyte. Thin hybrid electrolyte membranes are obtained using the tape casting method. Ceramic content of the hybrid electrolyte is varied up to 80-wt %.

Both LLZO powders and the hybrid electrolytes are characterized in regard to structure and electrochemical performance. Phase composition and crystal structure of the prepared powder are checked using X-ray diffraction (XRD). Morphology of powders and microstructure of the hybrid electrolytes are investigated with scanning electron microscopy (SEM). Thermal behavior of the hybrid electrolytes is examined using differential scanning calorimetry (DSC). Electrochemical impedance spectroscopy (EIS) is used to evaluate the ionic conductivity and special attention is paid to the ceramic polymer interaction. Its influence on lithium ion transport is discussed in detail.

We show that the combination of LLZO with polymer greatly simplifies the production of thin solid state electrolytes for lithium-ion batteries with only small losses in conductivity.