bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion Prevention Mechanism of Aluminum Metal in Superconcentrated Electrolytes
Authors: Chiang Ching Hua , Yamada Yuki , Sodeyama Keitaro , Wang Jianhui , Tateyama Yoshitaka , Yamada Atsuo
Published: February 2020

Metal corrosion is a serious problem that has beset various electrochemical systems. For lithium-ion batteries, oxidative corrosion of an Al current collector has been a great challenge in designing new electrolyte materials, and only a few lithium salts (e.g., LiPF6) are in practical use. Lithium bis(fluorosulfonyl)amide (LiFSA, LiN(SO2F)2) has attracted increasing attention as a state-of-the-art Li salt due to its high thermal/chemical stability and highly dissociative nature, but LiFSA-based electrolytes are known to induce severe oxidative corrosion of the Al current collector, which limits its widespread applications in lithium-ion batteries. The present work shows effective suppression of Al corrosion up to 4.5 V vs Li+/Li by using highly concentrated LiFSA electrolytes.1-4 The corrosion prevention mechanism can be interpreted in relation to a remarkable change in solution structures; all solvent molecules coordinate to Li+ and free solvent molecules disappear over a certain threshold concentration, as is evident from both spectroscopic analyses and first-principle molecular dynamics simulations. The stabilization of the Al current collector through the control of electrolyte solution structures is advantageous over LiPF6-based electrolytes, because the present case does not depend on F-, which also has negative effects on battery performance. Using highly concentrated LiFSA/acetonitrile (AN) electrolytes without free solvent molecules (5.0 and 6.0 mol dm-
3), we demonstrated highly reversible charge-discharge cycling of both LiMn2O4/Li cell (with an Al current collector)3 and graphite/Li cell,2 which cannot be achieved in less concentrated electrolytes (3.0 and 4.0 mol dm-
3). Furthermore, the rate performance far exceeds that in a state-of-the-art commercial electrolyte. This finding of superior performance in superconcentrated electrolyte will be an important breakthrough in developing a new electrolyte design strategy for advanced high-rate lithium-ion batteries. 

1. Yuki Yamada et al., Chem. Commun., 49, 11194 (2013).

2. Yuki Yamada et al., J. Am. Chem. Soc., 136, 5039 (2014).

3. Yuki Yamada et al., ChemElectroChem, 2, 1687 (2015).

4. Yuki Yamada et al., J. Electrochem. Soc., 162, A2406 (2015).

Figure 1
Superconcentrated Electrolytes for Sodium-Ion Batteries
Authors: Takada Koji , Yamada Yuki , Wang Jianhui , Lien Chien-Hung , Hirata Kazuhisa , Kawase Takeo , Yamada Atsuo
Published: February 2020

Sodium-ion batteries are receiving intense attention as an inexpensive yet high-performance rechargeable battery to possibly replace current lithium-ion chemistries in future. A myriad of positive and negative electrode materials have so far been reported for sodium-ion batteries and, interestingly, some of them exhibit superior performance (e.g., voltage, capacity, kinetics, or cycleability) than state-of-the-art electrodes for lithium-ion batteries. On the other hand, there are only a few studies on liquid electrolyte design for sodium-ion batteries. In particular, high reductive/oxidative stability is strongly required for electrolyte materials to achieve prolonged charge-discharge cycling of hard carbon anodes and high-voltage cathodes. Recently, superconcentrated electrolytes are being recognized as a new class of highly stable electrolytes for lithium-based batteries.1-3 In the present work, we report basic physicochemical and electrochemical properties of sodium salt-based superconcentrated electrolytes. First, we study the effects of cations, anions, and solvents on the ionic conductivity and viscosity of electrolytes at various concentrations. Based on the results, important factors to dominate the physicochemical properties are discussed. Next, we study charge-discharge behavior of hard carbon and sodium metal electrodes in sodium salt-based superconcentrated electrolytes. We have found much better cycleability of the electrodes in superconcentrated electrolytes than in conventional dilute electrolytes, suggesting that the sodium salt-based superconcentrated electrolytes have enhanced reductive stability.

1. K. Yoshida et al., J. Am. Chem. Soc., 133, 13121 (2011).

2. Y. Yamada et al., J. Am. Chem. Soc., 136, 5039 (2014).

3. Y. Yamada et al., J. Electrochem. Soc., 162, A2406 (2015).
Novel Sodium Tin Sulfides As Electrolyte for Solid State Sodium Ion Batteries
Authors: McDaniel Malte , Xiong Shan , Wang Hai , Chen Hailong
Published: February 2020

Safety concerns on conventional lithium ion batteries are attracting a lot of attentions from both academia and industry as the electric automobile market is fast growing. Replacing the organic, liquid, flammable electrolytes in conventional lithium ion batteries with inorganic, solid, nonflammable electrolytes can potentially eliminate the fire hazard of the batteries. However, currently the performance of all solid state lithium ion batteries are limited by a number of factors, including the low ionic conductivity and high interfacial resistance. On the other hand, low cost electrochemical energy storage technologies beyond lithium chemistry are also much desired for large scale applications.

                In this work, we report the synthesis and electrochemical testing of several sodium tin sulfides as solid electrolyte for sodium ion batteries, aiming to combine the advantages in safety for solid state batteries and the low cost of the sodium chemistry. Na4SnS4 was synthesized by solid state reactions in pure phase. In situ XRD study on the synthesis process were used to reveal the formation mechanism of this compound. The Na ion conductivity of this compound at various temperatures was measured by using electrochemical impedance spectroscopy. The relationship between the conductivity and synthesis condition and starting materials are discussed. Full cells with using this compounds as the electrolyte were also fabricated with various methods and the electrochemical cycling performances of the cells were tested. The mechanical properties of the electrolyte and the full cells were also measured and discussed. Several other sulfides are also successfully synthesized in pure phase. Their conductivities were also measured and compared with Na4SnS4. These novel Na ion conductors provides new promise for developing high performance all solid state sodium ion batteries.

Figure caption: Figure 1. X-ray diffraction pattern of Na4SnS4 sample

Figure 1
Liquefied Gas Electrolytes for Electrochemical Energy Storage Devices
Authors: Rustomji Cyrus Sam , Yang Yangyuchen , Kim Taekyoung , Caldwell Elizabeth , Yoon Hyojung , Meng Ying Shirley
Published: February 2020

Using electrolytes based on Liquefied Gas Solvents, high performance of both Li-Ion Batteries and Electrochemical Capacitors at temperatures as low as -60 °C has been demonstrated for the first time. Current Li-Ion technology necessitates the use of particular electrolyte solvents which are highly viscous and have relatively low electrolytic conductivity, preventing high performance below -20 °C. Further, Electrochemical Capacitors commonly use a toxic electrolyte for operation down to -40 °C. Using mild pressures to turn solvents which are typically gaseous at room temperature into a liquid phase, electrolytes with low melting points, low viscosities and moderate dielectric constants have been realized.  A number of various solvent and salt systems have been characterized, some showing exceptionally high electrolytic conductivity over a very broad temperature range for both Li-Ion and Electrochemical Capacitor electrolytes. Novel mechanisms for the superior ionic conductivity in these solvents have been studied. Further, these solvents show a wide potential window of stability which may enable high voltage devices. We gratefully acknowledge funding from DOE ARPA-E (DE-AR0000646).
High-Rate Sodium Ion Batteries: Synergetic Effect of Robust Surface and Nano-Rod Primary Particles As Cathode Material for Sodium Ion Batteries
Authors: Hwang Jang-Yeon , Sun Yang-Kook
Published: February 2020

Nowadays, to adjust the fluctuations in electricity production and efficient use of midnight off-peaks for stable energy supply, the mid-large scale battery system has been growing up [1]. In particularly, sodium ion batteries have many interests as an alternative candidate for cost-advantage versus lithium ion batteries because of large amounts of reservation of sodium resources in earth. However, intrinsic structural disadvantage of interstitial tetrahedral sites dissimilar to the O3 structure led to the low discharge capacity and cycle retentions and it have not yet satisfactorily addressed. Recently, to breakthrough present drawbacks, we suggested the new concept of radially aligned hierarchical columnar structure with varied chemical composition.

To further study of novel nano-structured with varied chemical composition materials, we carry out the synthesis and characterization of O3-type layered structure cathode material of constant concentration Na[Ni0.60Co0.15Mn0.25]O2 and full concentration gradient Na[Ni0.61Co0.12Mn0.27]O2 material. Through the comparison of electrochemical properties and related structural properties, herein, we investigated and defined the novel concept FCG materials.

Especially, we focus on the effect of particle morphology and micro structured properties by using micro scope technique. We believe that the unexplored site of radially assembled nano-rod structure primary particles having varied chemical composition is highly contribute to high power and high energy Na-ion battery systems.

References

[1]         B. Scrosati, J. Hassoun, Y. K. Sun, Energy Environ. Sci. 2011, 4, 3287

[2]         J.-Y. Hwang, S.-M. Oh, S.-T. Myung, K.-Y. Chung, I. Belharouak, Y.-K. Sun. Nat. Commun. 6 (2015) 6865.
Sodiation Kinetics of Metal Oxide Conversion Electrodes: A Comparative Study with Lithiation
Authors: He Kai , Lin Feng , Zhu Yizhou , Yu Xiqian , Li Jing , Lin Ruoqian , Nordlund Dennis , Weng Tsu-Chien , Richards Ryan M , Yang Xiao-Qing , Doeff Marca , Stach Eric A. , Mo Yifei , Xin Huolin L. , Su Dong
Published: February 2020

The development of sodium ion batteries  (NIBs) can provide an alternative solution to lithium ion batteries  (LIBs) for sustainable, low-cost energy storage. Due to the many similarities between sodium and lithium chemistries, the development of sodium-ion batteries (NIBs) – in particular the discovery and development of electrode materials – has been benefited greatly from the knowledge developed in understanding lithium chemistries in LIBs. However, many electrode materials used in LIBs show an inferior performance in sodiation. For example, in transition metal oxides MOx (M = Fe, Co and Ni), the sodiation reactions have shown much lower capacity and slower kinetics than those commonly observed in lithiation reactions. This could not be simply interpreted from the difference in the ionic size of Na+ and Li+ because the reaction happened in this system is not intercalation but conversion. For the conversion compounds, although there were many papers published to investigate their electrochemical performance, the origin of different reaction kinetics is still not clear which hinder the further study on this system.

To address this issue, we present herein our comprehensive, systematic study of the sodiation and lithiation of a model MOx conversion compound, viz., nanostructured sheets of NiO. We investigate the sodiation and lithiation processes using a combination of multiple temporal- and spatial-scaled characterization techniques, including electrochemical measurements, in situ transmission electron microscopy (TEM), and ab initio molecular dynamics (MD) simulations. From the in situ TEM, where our previous results showing the lithiation heterogeneous reaction pathways, we found the sodiation only go through a “shrinking-core” pathway and further sodiation was blocked by a crystalline passivation layer of Na2O that formed at an early stage. Our MD simulation shows that the sodiation pathway originates from a layer-by-layer reaction that occurs during the insertion of Na ions; this was the rate-determining step for the entire process. In case of lithiation, however, the formation of Li anti-site defects significantly distorts the local NiO lattice, which thereby facilitates Li insertion and enhance the overall reaction rate. In conclusion, the intrinsic layer-by-layer sodiation reaction and the formation of a crystalline passivation layer of Na2O play an important role for sluggish sodiation reactions.
New Methods for Understanding Stacking Disorder in Honeycomb-Layered Batteries: Insights into Synthesis Mechanism and Influence on Electrochemical Performance
Authors: Khalifah Peter , Liu Jue , Bo Shou-Hang , Yin Liang , Ma Jeffrey , Wu Lijun , Bai Jianming , Zhu Yimei , Bak Seong-Min , Yu Xiqian , Yang Xiao-Qing , Grey Clare P.
Published: February 2020

The layered alpha-NaFeO2 structure is one of the most important structural families for battery cathodes.  In recent years, it has been found that a honeycomb-layered superstructure of the basic alpha-NaFeO2 structure type can produce enhanced specific capacities for Li-ion batteries (Li-excess compounds with Li2MnO3 motifs) and enhanced voltages for Na-ion batteries (compounds such as Na3Ni2SbO6 for which the entire discharge capacity is delivered above 3.0 V vs. Na+/Na).  However, the crystallography of honeycomb-layered compounds is very complex, which results in the occurrence of both disordered and ordered polymorphs as well as complex long-range c-axis superstructures whose origin has not previously been determined.  New tools for investigating, classifying, and quantifying the disordered in honeycomb-layered compounds have been developed and applied to Na-ion cathode materials with this structure type with an emphasis on the “number” faults associated with the position of the central atom of the honeycomb lattice rather than the “letter” faults associated with the layer position relative to the close-packed atom planes.  This comprehensive work includes Rietveld refinements of synchrotron and neutron diffraction data, pair distribution function analysis, solid state NMR, TEM studies, and complementary electrochemical performance data.  It is demonstrated that there is a continuous spectrum of compositions with varying amounts of number disorder.  This number disorder is distinctly non-random, and the underlying thermodynamic reasons will be discussed, as well as the unusually slow reaction mechanism by which disorder is annealed out of the structure.  Since the structure of honeycomb-layered compounds are strongly dependent on the synthesis history, the methods for quantifying the degree of disorder that will be presented are particularly important if systematic studies on this important class of materials are to be carried out.  It is found that the degree of ordering has a clear impact on electrochemical performance, and thus control over sample disorder is required in order to attain the best cathode electrochemistry.
Rechargeable Zinc Batteries
Authors: Li Yun , Yang Jihui
Published: February 2020

Keyword: Rechargeable Zinc batteries, spinel ZnMn2O4, electrochemical reaction mechanism

Rechargeable Zn batteries, consisting of abundant, environmentally benign electrode materials that can be manufactured economically and theoretically provide decent energy density (around 400 Wh/kg), are regarded as promising alternatives to lithium-ion batteries. Combined with a Zn metal anode and an aqueous ZnSO4 electrolyte, MnO2­ and the Prussian blue hexacyanoferrates have been shown to work as cathode materials for rechargeable Zn batteries. However, the significant capacity fade during long-term cycling tests and insufficient energy density largely hamper their applications. Meanwhile, there are ongoing debates on reaction mechanisms of the Zn/MnO2 system.

In this study, our goal is to investigate the possibility of spinel ZnMn2-xTMxO4 as cathode materials for rechargeable Zn batteries, verify the reaction mechanisms, and eventually to achieve high voltage. Single phase ZnMn2O4 nanopowders with good crystallinity were synthesized by a combination of co-precipitation reactions and subsequent calcination technique, and the synthesis parameters were systematically optimized. We found that the calcination temperature has a significant influence on the crystallinity and morphology, thus electrochemical behavior of ZnMn2O4 nanopowders. The optimized ZnMn2O4 with ZnSO4 as electrolytes shows an initial specific capacity of 125 mAh/g at C/10. To elucidate the electrochemical reaction mechanism of ZnMn2O4, phase & chemical compositions, and microstructure of cathodes before and after cycling were systematically investigated. In parallel, ZnMn2-xFexO4 (0≤x≤2) has been synthesized and characterized.
Capacity Contributing Conductive Cathode Additive for Sulfur Batteries
Authors: Sun Ke , Su Dong , Cama Christina A , DeMayo Rachel , Huang Jianping , Zhang Qing , Marschilok Amy C , Takeuchi Kenneth J , Takeuchi Esther S , Gan Hong
Published: February 2020

The Lithium-Sulfur (Li-S) battery has been a subject of intensive research in recent years due to its potential to provide much higher energy density and lower cost than the current state-of-the-art lithium-ion battery technology.  However, both cell reaction active materials, sulfur and Li2S, are electronically non-conductive, which leads to the low electrode utilization and fast capacity fade during cell cycling.  Large amounts of non-active carbon host materials must be added to boost sulfur electrode electronic conductivity for high rate discharge, which lowers the sulfur electrode specific energy density.

Transition metal sulfides have been utilized as cathode material with high energy density and have been demonstrated to be rechargeable in lithium batteries.  Many of these sulfides are electronic conductive with conductivity comparable to that of graphite and carbon black.  Since they are also electrochemically active and can be cycled within the voltage window of sulfur battery, transition metal sulfides could be used as capacity contributing conductive cathode additive for sulfur batteries.

We have investigated Titanium Disulfide (TiS2), Pyrite (FeS2) and Cupric Sulfide (CuS) as capacity-contributing conductive cathode additives to the sulfur electrodes in Li-S battery.  Sulfur electrodes containing the metal sulfide additives showed improved power capability under high rate discharge.  While the cyclability of the hybrid electrodes vary widely depending on the type of conductive additive, different and unique electrochemical behaviors were observed for hybrid electrodes with TiS2, FeS2 and CuS respectively.  Improved coin cell cycling performance was observed with TiS2 as the cathode additive at 1C discharge rate.  The TiS2 distribution within the hybrid electrode showed significant impact on cell cycling capacity fade.  The mechanisms associated with the electrochemical performance of each chemical system are discussed.
High Capacity Li-S Secondary Battery Using Vertically-Aligned CNT Electrode
Authors: Fukuda Yoshiaki , Nozue Tatsuhiro , Nakano Haruhisa , Tsukahara Naoki , Murakami Hirohiko , Omoda Ryo , Yamada Takanobu , Ito Seitaro , Aihara Yuichi
Published: February 2020

In recent years, the lithium-sulfur (Li-S) secondary battery has been energetically researched   worldwide as a good candidate for next-generation secondary batteries. The sulfur active material has a theoretical capacity of 1675 mAh g-1and is abundant and highly inexpensive. However, several issues are associated with the use of Li-S secondary batteries, such as low utilization due to the insulating property of sulfur and the redox shuttle phenomenon caused by the dissolution of polysulfides generated during the discharge process.

In the present work, we have developed a Li-S secondary battery using the carbon nanotube (CNT) technoloy. Multiwalled-CNTs were directly grown on a nickel current collector by using the thermal chemical vapor deposition (CVD) method. The CNT films were used as the electrode for the Li-S battery. The S-CNT cathode was fabricated by impregnating it with molten sulfur. Then, sulfur powder was uniformly placed on the CNT film and heated at more than the melting point of 113°C. Our CNT has a diameter of 10-15 nm and a length of 200-600 µm. Therefore, the CNT electrode has a wide reaction area owing to its large specific surface area. In addition, the active materials can react rapidly because the electrons quickly access through the CNTs that connect directly with the current collector.

At IMLB 2014, we reported that coin-cell-type Li-S batteries with a sulfur loading of up to 10 mg cm-2 operate at a current density of 0.5 mA cm-2 [1]. However, more sulfur loading is required, in order to achieve the electrode capacity of 300 Wh kg-1 for practical usage. As sulfur loading increased to more than 10 mg cm-2, the discharge capacity decreased dramatically, probably owing to be attributed to inhomogeneous sulfur distribution in the CNT film. Moreover, the CNT films fell off the nickel current collector because of the shrinkage of the CNT bundles owing to the absorption of sulfur. Therefore, we attempted to synthesize harder CNT films with homogeneously impregnated sulfur. A thick amorphous carbon layer was coated on the CNTs by optimizing the thermal CVD process, thus making the CNT films harder. Moreover, the adhesiveness between the CNTs and the nickel current collector was enhanced, which improved CNT exfoliation. For homogeneous distribution, sulfur impregnation was performed in vacuum. The sulfur was considered to spread over the CNT films more uniformly. We could obtain the stable coin-cell-battery performance with sulfur loading of up to 20 mg cm-2, and the capacity was estimated to be more than 300 Wh kg-1 [2]. We manufactured 1 Ah-class pouch cell, with electrode surface area of 50 cm2.

Reference

[1] N.Tsukahara, presented at The 17thInternational Meeting on Lithium Batteries, Como, 2014 (unpublished)

[2] T. Yamada, presented at The 56th Battery Symposium, Nagoya, 2015 (unpublished)

Figure 1
Redox Flow Lithium-Oxygen Battery with Unprecedently Low Charging Overpotentials
Authors: Zhu Yun Guang , Jia Chuankun , Wang Xingzhu , Yang Jing , Wang Qing
Published: February 2020

Lithium oxygen battery (LOB), as a promising next generation energy storage system, has attracted tremendous attention. However, for aprotic systems due to the deposition of insoluble and insulating discharging product Li2O2, surface passivation and pore clogging of the cathode occur. As a result, the charging overpotential of LOB is generally intolerably high. While people have tried to use homogeneous catalysts — redox mediators dissolved in the electrolyte to address the above issues, the passivation and clogging problems remain especially at deep discharge. Inspired by the redox targeting concept in redox flow lithium battery, we have recently proposed a new battery concept — redox flow lithium oxygen battery (RFLOB), which elegantly resolves the surface passivation and pore clogging issues.1-3 As shown in Figure 1, with a pair of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) redox catalysts, the formation of Li2O2 during discharge and oxidation during charge could be performed in a separate gas diffusion tank rather than on the cathode in the cell. Therefore, the passivation and clogging problems of the electrode are feasibly obviated.4 Here, we will report a series of robust redox mediators as efficient ORR and OER catalysts in the RFLOB system. By optimizing the electrolyte compositions, extremely low charging overpotential (~0.20 V) has been achieved, which results of unprecedently high voltage efficiency. The underlying mechanism of the redox catalytic processes toward ORR and OER will be discussed in detail. We anticipate RFLOB provide a new vista to the development of Li-air battery with high round-trip efficiency for practical applications.

Figure 1. The structure of a redox flow lithium oxygen battery.

Reference:

                (1)           Wang, Q.; Zakeeruddin, S. M.; Wang, D.; Exnar, I.; Grätzel, M. Angewandte Chemie International Edition
2006, 45, 8197.

                (2)           Huang, Q.; Li, H.; Gratzel, M.; Wang, Q. Physical Chemistry Chemical Physics
2013, 15, 1793.

                (3)           Pan, F.; Yang, J.; Huang, Q.; Wang, X.; Huang, H.; Wang, Q. Advanced Energy Materials
2014, 4, n/a.

                (4)           Zhu, Y. G.; Jia, C.; Yang, J.; Pan, F.; Huang, Q.; Wang, Q. Chemical Communications
2015.

Figure 1
Effects of Alkyl Phosphonate Surface Coatings on High-Voltage LiMnxNiyCo1-x-YO2 (NMC) Cathode Performance
Authors: Chang Wansoo , Slaymaker Laura E. , Hamers Robert J , Mahanthappa Mahesh K.
Published: February 2020

We describe the effects of alkyl phosphonate surface coatings applied to LiMnxNiyCo1-x-yO2 (NMC) cathode materials on battery performance. A homologous series of alkyl phosphonic acids with hydrocarbon chains ranging from ethyl (C2) to octadecyl (C18) were solution grafted onto the surface of NMC cathode particles. For each phosphonic acid, we observed comparable grafting densities onto the NMC surface except for the hexyl phosphonic acid as demonstrated by XPS analyses. Analyses of alkyl phosphonate coatings using diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), showed that crystallinity of the coating layer increases with alkyl chain length. We fabricated cathodes comprising NMC coated with various alkyl phosphonates, incorporated them into half-cells, and assessed their electrochemical performance by subjecting them to 100 charge/discharge cycles and to charge/discharge rate performance tests. Electrochemical impedance spectroscopy (EIS) analyses of alkyl phosphonate-coated cathodes before and after the rate tests revealed that the long chain alkyl phosphonate coatings mitigate electrolyte degradation (1 M LiPF6 in ethylene carbonate/dimethyl carbonate) at the electrode surface. However, cathodes with long chain alkylphosphonate coatings exhibit poor high C-rate performance as compared to the shorter alkylphosphonate coatings. These findings are rationalized in terms of the crystallinities of the different coating layers.
Dual Nature Embedded Electrode Investigated through Deis Technique for Lithium Ion Sulfur Battery
Authors: Gangadharan Ananya , S Ramaprabhu , Vedarajan Raman , Matsumi Noriyoshi
Published: February 2020

The development of new energy storage technology has become an essential part to sustain the growth and progress of the society. In this respect, lithium ion batteries are one of the promising candidates to alleviate the growing energy crises and are attractive from the stability point of view but it is lacking the high power density and energy density. Lithium sulfur battery has high theoretical energy density of 2600 Wh/kg, and the abundance of sulfur open the scope of the battery to meet the market requirements. We report the lithium ion sulfur characteristics of the battery by using a versatile technique called dynamic electrochemical impedance spectroscopy analysis (DEIS). The cell configuration based on partially exfoliated carbon nanotube, graphene, and sulfur composite used as cathode and lithium foil as anode in LiTFSI, DOL/DME electrolyte, shows dual electrochemical behavior. The morphological features of the electrode material are probed by transmission electron microscopy as well as scanning electron microscopy. Through analysis of DEIS, cyclic voltammetry and galvanostatic cycling reveal dual nature of Li-ion and Li-S batteries. The cell operated in Li-ion battery condition shows a stable capacity of about 900mAh/g.
Enhanced Performance of Li-S Batteries By PANI Printing Method
Authors: Moon San , Jung Young Hwa , Kim Do Kyung
Published: February 2020

Lithium-sulfur (Li-S) batteries have received considerable attention, since their theoretical energy density (2500Wh kg-1) is ~7 times larger than those of the current LIBs (~387Wh kg-1) utilizing the unparalleled theoretical capacity of sulfur (1,675 mAh g-1). The practical application of Li-S cell is still limited mainly due to the low conductivity of sulfur (~10-30 S cm-1), the volumetric expansion up to 80% during the discharge and the dissolution of polysulfides resulting shuttling effect in the charge-discharge process. In the present investigation, we develop a printing method for enhancing the lithium sulfur batteries. PANI layer coated sulfur electrode was demonstrated by a simple printing method. The role of printed layer is confirmed by in-situ UV/Vs test. The PANI layer avoids the chronic issues previously reported in lithium-sulfur batteries. In particular, the printing method is able to enhance the lithium-sulfur cell and the printed layer plays an important role as an electrolyte-blocking layer, preventing the dissolution of polysulfides. In the printed sulfur electrode, the capacity retention was 96.4% with 99.6% of average Coulombic efficiency (1C cycle), and 105% of the original capacity was still retained with 99.3% of average Coulombic efficiency (0.1C cycle). This effect induces the stable cycling capacity of sulfur electrode. The strategy employed in this work to produce a uniform PANI layer printed onto electrode surface is also applicable to all of other sulfur electrode to develop stable cell that avoid the shuttling effect.
Cluster-Based Reduced-Order Modeling of Lithium-Ion Battery
Authors: Esfahanian Vahid , Shahbazi Ali Akbar
Published: February 2020

The Lithium-ion batteries are certainly the battery of choice today because of their high voltage platform, low maintenance, high energy and power density, good cycle performance, and low self-discharge. Developments in lithium-ion battery technology make them inexpensive, small and extremely light-weight. These batteries are capable of providing the great power needs of today’s high-tech industries, ranging from small portable devices, e.g. smart phones, to full/hybrid electric vehicles and also alternative energy storage requirements of renewable power generation. The lithium-ion battery performance plays a significant role in the system energy management. As a consequence, battery real-time monitoring and accurate state-of-charge (SOC) estimation are necessary. However, full order electrochemical models are not suitable for this purpose due to high computational cost. Reduced order model (ROM) is one of the promising models which is computationally cost effective while ensuring accurate results. Using data clustering are one of attractive ways to make reduced order model. The capability of cluster-based reduced order modeling (CROM) has been proven in fluid mechanics engineering fields. This approach, starts with a snapshot data set. The observations are clustered based on their similarity and then the means of these clusters (centroids) are used to constitute the reduced order basis.

   In the present study, cluster-based reduced order modeling is applied to electrochemical transport governing equations in order to simulate a lithium-ion battery. For this purpose, the governing equations including conservation of species and charge are solved all together using finite volume method (FVM) by which the snapshot data are provided. The data are clustered by k-means clustering algorithm in order to obtain the centroids which are optimal low-dimensional basis for representing an ensemble of high-dimensional simulation data. This low-dimensional basis are used to formulate reduced order models of complex fields of battery. The obtained numerical results show that not only the CROM of lithium-ion battery significantly decreases the computational time but also there is an excellent agreement with the results of computational fluid dynamics (CFD) models, consequently is suitable for deployment in real-time monitoring and battery management systems.
A Novel Fe3O4/Carbon Nanofiber Paper (CNP) Composite As Free-Standing Anode for Lithium-Ion Battery
Authors: Liu Zhu
Published: February 2020

Abstract: Fe3O4 is an attractive alloy-type anode material because of its high known capacity (924mAh/g). However, Li+ insertion into and extraction from Fe3O4are accompanied by a huge volume change,up to 90%, which induces a strong strain on Fe3O4 and causes pulverization and rapid capacity fading due to theloss of the electrical contact between part of Fe3O4 and current collector.We report an advanced Lithium-ion battery based on a free standing carbon nanofiber paper(CNP) ink and Fe3O4 anode that overcome the pulverization problem. The Fe3O4 nanoparticles were electrochemically grown on self-supported CNP. It could be used as a kind of metallic-free current collector anode for Lithium-ion battery, which would significantly reduce the mass of the whole anode by 66 %. The new flexible Fe3O4/CNP composite anode achieves a higher initial reversible capacity of 1120 mAh/g and exhibits more stable performance compared with Fe3O4 anode coated on Cu foil by traditional electrode-fabrication technique. This is due to that the flexible 3D porous structured Fe3O4/CNP composite is light weight and can accommodate the volume change of Fe3O4 during the lithiation/delithiation process, and promotes the diffusion and transfer of lithium ionand electron, respectively. Compared with the pure Fe3O4nanoparticles, the Fe3O4/CNP exhibited a better cycling stability, because the carbon nanofiber with high mechanical strength and elasticity can work as a buffer to prevent the volume expansion and contraction of Fe3O4 nanoparticles during the Li+ insertion/extraction process. Meanwhile, compared with single CNP, the Fe3O4/CNP showed a higher capacity because of the hybridizing with higher capacity Fe3O4 nanoparticles. Moreover, this Fe3O4/CNP composite anode displays excellent rate capability, which maintains a discharge specific capacity of 210 mAh/g when the applied current rate is 10 C and still delivers 1150 mAh/g after returning to 0.2C. The excellent electrochemical performance of the Fe3O4/CNP as an anode material in Lithium-ion battery was obtained. Our work provides a new way to develop novel electrode structure for light-weighted and flexible Lithium-ion battery.
Graphene/Na Carboxymethyl Cellulose Composite for Li-Ion Batteries Prepared By Microwave Enhanced Liquid Exfoliation
Authors: Naboka Olga , Yim Chae-Ho , Abu-Lebdeh Yaser
Published: February 2020

Graphene and its composites have great potential as anode materials for Li-ion batteries (LIB) since their capacity was reported to exceed that of graphite, currently used as anode in most LIB [1].There are many methods to synthesize graphene, but there are still challenges to produce graphene at a large scale with desired properties that suit its perspective applications. Since there is yet no universal method for graphene production, especially that gives high yield, it would be reasonable to develop methods adjusted to specific applications e.g. electrochemical energy storage.

Liquid ultrasonic exfoliation of graphene is very popular technique however satisfactory yield of exfoliation is usually achieved with either toxic organic solvents or in the water solutions of surfactants, the latter results in contaminated final product, which is unacceptable for electrochemical applications.

In our work we used sodium carboxymethyl cellulose (NaCMC) as a water soluble “green” exfoliating agent for the high-yield graphene preparation. Since NaCMC is known to be a good binder for active electrode masses there is no need to remove it from as prepared graphene. Such approach allowed us simultaneous synthesis of graphene and preparation of electrode material for LIB.

Microwave assisted method for the liquid phase graphite exfoliation was developed in the present work. Addition of microwave heating step to sonication of graphite dispersions in solutions of sodium carboxymethyl cellulose (NaCMC) resulted in formation of concentrated graphene dispersions of up to 4.3 mg/ml after 10 hours of sonication; concentration of graphene was increased for 34% compared to using sonication alone. HRTEM and Raman spectroscopy revealed formation of few-layer graphene (3-4 layers). It was found as well that graphene yield depends on the molecular weight of the NaCMC – the higher molecular weight the higher graphene yield (up to 59% increase of graphene yield was observed for NaCMC with 250000 molecular weight compared to NaCMC with 90000 molecular weight). Drying of prepared dispersions resulted in the graphene/NaCMC composites with graphene content up to 38.65%. Yield and concentration of graphene can further be improved by increasing sonication time and recycling of sediment.

Graphene/NaCMC composite was tested as electrochemically active binder for using with Si nanoparticles in LIB electrodes. Si showed up to 51% capacity increase in the presence of graphene/NaCMC binder comparing to conventional NaCMC binder.

                                                                                                                 

N. Lavoie et al. in Y. Abu-Lebdeh and I. Davidson (eds) Nanotechnology for Lithium-ion batteries,117 (Springer, NY, 2013).

A. Cieselski, P. Samori, Chem. Soc. Rev. 43, 381 (2014).
Optimized Solid-State Reaction Process of Synthesizing Li4Ti5O12 with Improved Rate Capability for Li-Ion Batteries
Authors: Kim Jae Hyun , Baek Seong-Ho , Park Jung Soo
Published: February 2020

Spinel Li4Ti5O12 (LTO) has been actively studied due to its predominant properties in safety issue. LTO can be synthesized by different synthesis techniques including solid-state reaction, sol-gel, high energy ball milling, hydrothermal method, spray pyrolysis, etc. Among these synthesizing methods, the solid-state reaction method is the most commercially available process. It is very important to reduce calcination temperature and time in mass production using solid-state reaction. We prepared several sets of LTOs using commercially available precursors (TiO2) which have various particle sizes. We also varied calcination temperature in each fixed TiO2 particle size. We found the optimum process condition that has the best electrochemical properties. The sizes of the TiO2 precursors are 15 nm, 25 nm, 32 nm, and 40 nm. The calcination temperatures are 700 °C, 750 °C, 800 °C, and 850 °C. The calcination time (36 hr) is too long to prepare single phase LTO at 700 °C. The single phase LTOs are obtained in all the size of the used TiO2 particle at 800 °C and 850 °C, but the LTO particles are 1 ~ 2 um, which is too large. The pure LTOs are synthesized in all the TiO2 particle size except for 15 nm at 750 °C. The calcination time was varied from 36 hr to 1hr.

 The rate performance is conducted in all the fabricated samples. When the calcination time is 36hr, the best capacity is obtained in the sample, which 32 nm TiO2 particle is used. At 50 C, the capacity of the sample was 88 mAh/g when the 32 nm TiO2 precursor is used. The synthesized LTO at 750 °C shows best capacity of 122 mAh/g when the calcination time is 1 hr. The best electrochemical performance was due to small particle size, resulting in fast Li-ion diffusion and larger contact area between particles. We also fabricated Li-ion capacitor using the LTO and investigated the electrochemical behaviors.
Improving Lto Performance: Cold Crank, Gassing and Life Studies
Authors: Margez Carine L , Tan Bing , Greszler Thomas A
Published: February 2020

SAFT America is developing an LMO/LTO lithium ion cell design for vehicle application in collaboration with U.S. Advanced Battery Consortium (USABC) . 

The first two targets set by SAFT are meeting cold crank requirements at -30°C  set by USABC and solving gassing issues.

Different electrode formulations, electrolytes and cell designs have been investigated to successfully pass cold crank testing. A specific non carbonate electrolyte satisfies cold crank requirements down to 15% state of charge.  Moreover new electrode formulations may potentially help meet cold crank requirements using carbonate electrolytes.

In addition, SAFT will share the outcome of recent electrolyte screening, cycle life improvement and impedance growth reduction experiments. From the results, the gassing mechanism of LTO can be inferred and will be discussed.

Figure 1
Failure Evaluation of Li-Rich Cathode Li-Rich Cathode (Li[NixLi(1-2x)/3Mn(2-x)/3]O2) Materials In Novel in-Situ electrochemical Mass Studies of Lithium Ion Battery
Authors: Wang Fu-Ming , Yeh Nan-Hung
Published: February 2020

In the presence of literatures [1-4], high-voltage (> 4.8V; 5V class) Li-rich layer compounds (Li[NixLi(1-2x)/3Mn(2-x)/3]O2) have been reported to the next candidate of cathode materials in order to increase the power and energy density instead of LiCoO2 or LiNixMnyCozO2 conventional materials. These high-voltage Li-rich layer materials dedicate their high reversible capacities more than 270 mAh g-1, which is almost twice as higher as LiCoO2. However, this material suffers dramatically challenge due to the irreversible phase change in the first charge. Several studies had discussed the failure mechanism of this high voltage material; however, those comments are different. Mantia et al. [1] have demonstrated direct evidence of oxygen evolution from the Li-excess material at high potentials by in situ differential electrochemical mass spectrometry (DEMS) as well as Hy et al. [2] shown an oxygen activation occurs following electrochemical reaction and forms an irreversible formation of Li2O by surface enhanced Raman spectroscopy (SERS). In Jiang’s result [3], they are unable to detect any oxygen in their ex situ observation. Their XRD pattern and 6Li MAS NMR spectrum comment O2- loss is accompanied with the electrolyte to form CO2.

In our novel in-situ gas evolution experiment, we showed that there are two reaction mechanisms in the first charge process in Figure 1. In the first reaction mechanism, the CO2 (m/z 44) and CO (m/z 28) generate drastically at the potential of 4.25V. In comparison with cyclic voltammogram (CV) (not shown in here), the potential of 4.25V is indicated to the reaction of Ni3+/Ni4+; therefore, the gas evolution at this stage can be concluded the electrolyte is partially decomposed with the catalyst of Ni3+/Ni4+ and the oxygen evolution is not correlated. Second reaction mechanism starts at 4.65V, the CO2forms solely in accompanied with oxygen evolution (m/z 32) from cathode material. Above result indicates that the second reaction mechanism is lead by the oxygen evolution and further reacts with electrolyte.

In this research, we establish a novel in-situ observation for evaluating gas evolution and define the reaction mechanisms of high voltage cathode material.

Reference

[1] F. La Mantia, F. Rosciano, N. Tran, P. Novak, J. Appl. Electrochem. 38 (2008) 893

[2] Sunny Hy, Felix, John Rick, Wei-Nien Su, Bing Joe Hwang, J. Am. Chem. Soc. 136 (2014) 999

[3] Meng Jiang, Baris Key, Ying S. Meng, and Clare P. Grey, Chem. Mater. 21 (2009) 2733

Figure 1
Locally Structural Evolution of Silicon Anode in Lithium-Ion Battery Investigated By in-Situ Synchrotron X-Ray Diffraction and Absorption Spectroscop
Authors: Chen Shi-Wei , Chen Tsan-Yao , Lee Ching-Yun
Published: February 2020

With the possible exhaust of fossil oil, effective utility of energy becomes an important issue, clean energy and rechargeable energy are thus highly developed. In which, rechargeable lithium-ion batteries attract much attention because of its extensive use such as portable electronic devices, powering hybrid electric vehicles (HEV) and zero-emission vehicles (ZEV). While, capacity and charging rate are needed to be highly improved for the utility in practice. Advancing battery with silicon anode thus becomes increasingly emphasized in the recent years because of the ultra-high theoretical capacity. But the dramatic volume expansion of silicon anode hinders its real utility. Lots of studies focus on this phenomenon and try to overcome this issue with specific design of nano-structure and so on. But one can’t get constant rule to stabilize silicon anode because the real mechanism of volume expansion has not been explored in detail. We thus intend to explore the structural evolution of silicon anode in detail by in-situ charging/discharging synchrotron x-ray techniques, to dig out the mechanism of volume expansion in silicon anode, in this study.

        Initially, hollow silicon spheres are synthesized by the reduction of SiO2 surface and selective corrosion. After the measurements of CV, capacity and life time, in-situ charging/discharging synchrotron x-ray diffraction and absorption spectral analyses are used to probe structural variation in silicon anode. At the first cycle of lithiation, silicon structure gradually transforms from crystalline to amorphous and finally changes to Li15Si4 alloy phase. The created defects in silicon anode contribute to the structural disintegration and reconstruction as indicated by the x-ray line profile analysis. The change in local structure can also be evidenced by x-ray absorption near edge spectroscopy (XANES). Lithium ions cause Si-Si bond-breaking and result in the formation of identical short range ordering of Li15Si4.

        With the macro and micro analyses of structures, volume expansion of silicon anode with phase transformation has be expounded in detail. Results in this study could be the fundamental to design silicon anode with stable structure, facilitating the utility of Li-ion battery with ultra-high capacity in practice.
Synthesis LiMn0.7Fe0.2Ni0.1PO4 and Carbon Coating with Cassava Powder and Citric Acid as Carbon Source
Authors: Prihandoko Bambang
Published: February 2020

Lithium ion battery has high energy density. LMPO4 is a cathode active material with good performance and almost commercial battery in the world.  The substitution of Fe and Ni was used in synthesis of LiMnPO4 with composition of LiMn0.7Fe0.2Ni0.1PO4 . In this experiment LiMn0.7 Fe0.2 Ni0.1PO4  was carried out with stoichiometric composition of technical raw materials, MnO2 and Fe2O3 from China, Ni from Merck, H3PO4 and LiOH.H2O from Germany. After calcinations process at 7000C in 2 hours and sintering 8000C in 4 hours by powder metallurgy method, the powder was milled and mixed in shaker mill with tapioca or cassava powder under comparison between tapioca and active material 1:7, 1:8, 1:9 in 1 hour. The mixed powder was heated at 8000C in 2 hours under nitrogen gasses. The heated powders was mixed with citric acid and was heated again at 8000C in 2 hours under nitrogen gasses. The produced powder was analyzed the characteristic of crystal structure, SEM, conductivity, cyclic voltammeter and charge – discharge. The produced powder has black color under coated carbon. The crystal structure of LiMn0.7Fe0.2Ni0.1PO4 \C has a base olivine structure of lithiophilite.

Keywords:

cathode, LiMnPO4, lithium battery, powder metallurgy, tapioca