bluuebunny/crossref_metadata_2025_split huggingface dataset:
Smoothing out NaxCo0.7Mn0.3O2 ocv Curve – Role of the Oxygen Nonstoichiometry
Authors: Molenda Janina , Baster Dominika 
Published: February 2020

It is well known that NaxCoO2-y exhibits complicated character of the OCV (Open Circuit Voltage) curve, with several potential plateaus and jumps in 2.0-3.8 V range [1,2]. Origin of such the behavior is commonly attributed to the Na cations ordering [3]. However, often neglected influence of the electronic structure of the cathode material, which manifest itself as an additional energy states present in the main energy gap, seems to play a major role in this case. These states can be directly related to the presence of the oxygen vacancies [4].
In this work we show a novel approach, based on the consideration of the influence of cation dopants replacing partially cobalt, which aims to smooth out the OCV characteristic of Na/Na+/NaxCoO2-y battery. On a basis of work [4], one can state that in order to remove most of the potential jumps, the material has to be oxygen stoichiometric (NaxCo0.7Mn0.3O2) and no sodium ordering should be present. Since +4 oxidation state for cobalt cations is not the most favourable one, it gives rise to a presence of the oxygen vacancies, which decrease the average oxidation state of Co. If an appropriate dopant with stable +4 state would be introduced in cobalt positions, the concentration of the oxygen vacancies shall decrease considerable. Furthermore, random distribution of such dopant in Co sublattice will diminish the tendency of Na cations to form ordered structure.
As predicted from the considerations shown above, in the case of Mn substitution, OCV curve of Na/Na+/NaxCo0.7Mn0.3O2 is almost completely smoothed out, with only one major potential jump, which is associated with x = 0.5 mol·mol-1. Apart from basic scientific aspect, the obtained result is interesting from the point of view of application, as in commercial batteries voltage cannot show any non-monotonous behaviour.

References:

[1] R. Berthelot, D. Carlier and C. Delmas, Nature Materials 10 (2011) 74.
[2] J. Molenda, C. Delmas and P. Hagenmuller, Solid State Ionics, 9-10 (1983) 431.
[3] Y. Meng, Y. Hinuma, G. Ceder, J. Chem. Phys. 128 (2008) 1047081.
[4] D. Baster, K. Dybko, M. Szot, K. Świerczek and J. Molenda, Solid State Ionics (2013) http://dx.doi.org/10.1016/j.ssi.2013.11.

Acknowledgements: The project was funded by the National Science Centre Poland (NCN) on the basis of the decision number DEC-2011/02/A/ST5/00447.
A Synergistic Approach to Reduce the Hysteresis in Conversion Reactions
Authors: Bernuy-López Carlos , Pérez-Villar Sofía , Galceran Montserrat , Muñoz Márquez Miguel Ángel , Casas-Cabanas Montserrat 
Published: February 2020

Keywords:Lithium-ion battery, conversion reaction, hysteresis, composite material
In order to expand the Li-ion battery (LIB) technology and to enlarge energy demanded applications such as the electrical vehicle, an increase in their energy storage density is needed. An alternative to common intercalation materials are the so-called conversion materials which undergo a multi-electron redox process [1]. Instead of inserting Li, these materials undergo reversible reduction to form metal nanoparticles M0 and binary Li compounds: Mn+Xy + nLi++ ne- ↔ M0 + yLiz/yX [2]. Transition metal oxides such as Fe2O3 or Fe3O4are examples of this type of materials and have largely been studied these last years due to their high capacity values, good cycleability, capacity retentions and low toxicity and cost [2]. However, they present some drawbacks such as large voltage hysteresis between charge and discharge, which would lead to an enormous loss of energy efficiency of the battery.
In this work we present a synergistic approach to reduce the hysteresis in conversion materials. To do so, C- FeOxcomposites with tailored microstructure are prepared using low cost methods. In the literature, carbon-metal oxide nanocomposites has already been used as a strategy to improve the cycleablity of conversion materials but no hysteresis reduction effect was previously observed [2, 3]. In our work, a significant hysteresis voltage reduction ( ≥ 0.3 V) will be shown through the combination of two materials reacting through different mechanisms (intercalation and conversion). The reduction of polarisation through a dual mechanism has been observed in the nanocomposite formed during the electrochemical reaction of titanium hydroxyfluoride [4] and is herein applied to abundant and low cost materials able to deliver much higher capacities. Insights about the electrochemical reactions and mechanisms taking place in these composite materials will be shown by means of TEM, XPS and in-situ Raman spectroscopy data.

References

[1] Armand, M.; Tarascon, J.-M. Nature 2008, 451, 652.
[2] Cabana, J.; Monconduit, L.; Larcher, D. ; Palacin, M. R. Adv. Mater. 2010, 22, E170.
[3] Zhang W.M. ; Wu X.L. ; Hu J.S. ; Guo Y.G : Wan L.J. Adv. Funct. Mater. 2008, 18, 3941.
[4] Dambournet, D. ; Chapman, K. W. ; Chupas P.J. ; Gerald, R.E.; Penin, N.; Labrugere, C.; Demourgues, A.; Tressaud, A.; Amine, K. J. Am. Chem. Soc. 2011, 133, 13240.
Materials Exploration in Na-Fe-S-O System: Synthesis and Electrochemistry
Authors: Oyama Gosuke , Barpanda Prabeer , Nishimura Shinichi , Yamada Atsuo 
Published: February 2020

The current Li ion batteries which employ layered oxides such as LiCoO2, spinel LiMn2O4, and olivine LiFePO4as cathode materials have dominated global markets of secondary batteries. However, rapid expansion of their application has triggered the growing concerns on scarcity and rising costs of Li resources. As one of the most realistic alternatives, Na ion batteries re-attract massive attention owing to its abundance, lower cost, and sustainable production. In this pursuit, Na-Fe-S-O systems are one of the most desirable systems, which are consisted only by earth-abundant and geographically distributed elements. Especially, sulfate compounds are very cheap, being a byproduct of coal power plant, or petrochemical industries.
During the exploration of in the Na2O-FeO-SO3 ternary phase diagrams, we identified some materials with a totally new composition and crystal structure [1]. The target cathode material was obtained via classical solid-state synthesis by ball-milling Na2SO4 and anhydrous FeSO4 followed by annealing the mixed precursors at elevated temperature under an Ar gas flow. The electrode property of as-synthesized cathode material was examined with no special effort for decreasing particle size or carbon coating. The working electrode was formulated by mixing 85 wt% active material, 10 wt% carbon black (Ketjen Black, ECP), and 5 wt% polytetrafluoro- ethylene (PTFE) binder. Figure 1 shows an example of galvanostatic charging and discharging curves measured at a rate of C/10. The initial charging capacity of 98 mAhg-
1 was retained over 10 cycles with small polarization. An average potential of 3.6 V (vs. Na/Na+) is the highest-ever Fe3+/Fe2+redox potential among all known Na-ion cathode materials. The smooth sloppy charging and discharging curves suggests a single-phase reaction mechanism, which is generally favorable from the perspective of homogeneity and kinetics of the reaction.
Details on the compositions and their synthetic conditions will be disclosed in the poster.

References

[1] A. Yamada, P. Barpanda, S. Nishimura, G. Oyama, Patent JP-2013-187914 (2013).

Acknowledgments

This work was supported by the ‘Element Strategy Initiative for Catalysts & Batteries’ (ESICB) project.
New Insight in Sodium Intercalation in MoS2 at Different Stages and the Optimized Cycle Performance for Sodium Ion Batteries
Authors: Wang Xuefeng , Wang Zhaoxiang , Chen Liquan 
Published: February 2020

Due to the high abundance and low cost of the sodium (Na), Na-ion batteries are an alternative to lithium-ion (Li-ion) batteries for large-scale energy storage, such as electric vehicles and stationary storage for renewable energies. Similar to the successful lithium intercalation chemistry, Na-ion batteries have recalled much attention recently and a significant achievement have been made. However, the large size of the ionic diameter and ionization potential of the Na ions make it difficult in structural stability and ion diffusion, usually resulting in different reaction mechanisms1.
Transition metal dichalcogenides MS2 (M=Mo, W) and their intercalated compounds belong to a large class of the so-called 2D layered solids. The layers of these materials consist of three interconnected, hexagonally coordinated atomic sheets (S-Mo-S)2. The weak interlayer van der Waals force permits the possible intercalation of some foreign atoms between the layers, such as alkali metal. Li-ion intercalated MoS2 (LixMoS2) has been widely explored and known as intercalation (x<0.5), 2H-1T phase transition (0.5<x<1) and conversion (x>1)3. However, few studies have been focused on the structural change of the host when Na ions are inserted into the MoS2 lattice. Moreover, the electrochemical performance of MoS2for Na-ion insertion needs to be improved.
In this work, in situ and ex situ techniques were combined to monitor the structural changes of MoS2 at atomic levels at various intercalation stages and recognize the reaction products. By optimizing the binder and the cut-off potential, we improve the cycling performance of MoS2 for Na-ion battery by a large margin. When discharged to 0.2 V, the cell shows an initial discharge capacity of 241 mAh g-1 and maintains at 165 mAh g-1 after 70 cycles. However, intercalation of too many Na ions in the host leads to the decomposition of MoS2 into metallic Mo and NaxS2 (x£2). The performance of the cell becomes deteriorated in the subsequent cycles due to large volume expansion and the electrolyte reduction at low potentials (0.01 V) though a reversible capacity up to 440 mAh g-1 can be obtained.
(1) Palomares, V.; Serras, P.; Villaluenga, I.; Hueso, K. B.; Carretero-Gonzalez, J.; Rojo, T. Energy Environ. Sci.
2012, 5, 5884-5901.
(2) Zak, A.; Feldman, Y.; Lyakhovitskaya, V.; Leitus, G.; Popovitz-Biro, R.; Wachtel, E.; Cohen, H.; Reich, S.; Tenne, R. J. Am. Chem. Soc.
2002, 124, 4747-4758.
(3) Fang, X. P.; Hua, C. X.; Guo, X. W.; Hu, Y. S.; Wang, Z. X.; Gao, X. P.; Wu, F.; Wang, J. Z.; Chen, L. Q. Electrochim. Acta
2012, 81, 155-160.
Electrochemical Performance of Polyoxometalates for Cathode Materials of Lithium Battery
Authors: Sonoyama Noriyuki , Uematsu Shinichi , Ni Erfu 
Published: February 2020

Polyoxometalates (POM) are very famous cluster ions that can be synthesized self-assembly formation in the solution. These cluster ions behave as independent molecules and show reversible redox activity in the solution. These molecular cluster ions are expected to show different property from the usual cathode materials for lithium ion battery those are the bulk continuum ionic crystals.[1-3] In this paper, we have synthesized Anderson-type POM Na3[AlMo6O24H6] (Fig.1 ) and examined its electrochemical property as cathode materials for lithium battery. In Anderson-type POM, all [MoO6] share the edge with hetero ion [AlO6]. This covalent bond of [MoO6] with unreactive hetero ion would stabilize the structure of the reduced POM.
Anderson-type POMs were synthesized according to the reported method. [4] Obtained samples were mixed with acetylene black with the weight ratio of 1:2 using ball mill. The charge-discharge test and AC-impedance spectra measurements are performed using the coin cells at 25ºC. Lithium metal was used as anode and 1M solution of LiPF6in EC:DEC (3:7 v/v%) was used as the electrolyte. After the charge-discharge measurements, ex-situ XRD and Raman measurements were carried out under Ar atmosphere again.
NMR, FT-IR and Raman spectra of obtained samples agreed with those for reported Anderson-type POM. In Fig. 1, the discharge-charge curves for Na3AlMo6O24H6 were shown. Na3AlMo6O24H6 mixed by ball mill show large capacity over 420 mAh/g. In Fig.2, cycle stability of Na3AlMo6O24H6 was shown. The cycle stability of Na3AlMo6O24H6 was higher than the most representative POM K3PMo12O40 with Keggin type structure. 90% of the initial discharge capacity for Anderson-type POM was retained after 50 cycles, whereas that for KPM decreased steeply in the first 10 cycles. This result suggests Anderson type POM has higher stability than Keggin type POM.
[1] N. Sonoyama et al, J. Power Sources, 196 (2011) 6822.
[2] S. Uematsu et al, , J. Power Sources, J. Power Sources, 217, (2012)13.
[3] E. Ni et al. J Nanopart Res, 15(2013) 1732.
[4] Kenji Nomiya et al. Polyhedron, (1987) 213.
Particle Shapes and Surface Structures of Olivine NaFePO4 for Sodium-Ion Batteries
Authors: Whiteside Alexander , Fisher Craig Andrew James , Parker Stephen C. , Islam M. Saiful 
Published: February 2020

The expansion of batteries into electric vehicle and grid storage applications has spurred the development of alternative cathode materials such as olivine phosphates. Building on previous studies of the lithium-ion cathode material LiFePO4, we present atomistic simulations of olivine-structured NaFePO4. We discuss differences in its morphology compared to its Li analogue, in the context of new simulations on the bulk properties.[1] The calculated equilibrium morphology is mostly isometric in appearance, with (010), (201) and (011) faces dominant. Exposure of a significant fraction of (010) surface is significant because it is normal to the most facile pathway for ion conduction. The equilibrium morphology of an NaFePO4 nanoparticle is proportionally thinner along the [010] axis than that of an LiFePO4 nanoparticle, which should also be beneficial for high ion intercalation-deintercalation rates because of the 1D nature of the conduction pathway.[2] We also simulated the effect of stabilising the (010) surface upon the particle morphology (shown below), concluding that a significant reduction in the surface energy is required to obtain the experimental “platelet” structure.

Figure: Variation in the equilibrium morphology of NaFePO4 with the (010) surface energy, all other surface energies being held constant.
[1] R. Tripathi, S. M. Wood, M. S. Islam and L. F. Nazar, Energ. Environ. Sci., 6, 2257-2264 (2013).
[2] A. Whiteside, C. A. J. Fisher, S. C. Parker and M. S. Islam, Phys. Chem. Chem. Phys. (2014) (submitted).
Hollow Carbon Nanosphere/Germanium Metal Composite Li-Ion Anode
Authors: Banek Nathan A , Hays Kevin Alan , Wagner Michael J 
Published: February 2020

Since their introduction, lithium ion batteries have become ubiquitous for powering portable electronic devices. However, the charging rate of graphite (by far the most common anode material) is dependent on lithium diffusion into the material. Highly graphitic hollow carbon nanospheres (HCNS) have a tremendous advantage over micron-sized graphite particles as the diffusion path length is on the nanoscale, 3 orders of magnitude shorter than graphite’s, facilitating rapid charging within a few minutes, rather than many hours. In addition, HCNS anodes cycle stably in inexpensive low melting electrolytes, cycling with excellent capacity retention and high rate at temperatures as low as -50 ˚C. Unfortunately, HCNS anodes have lower specific capacity compared to those made with graphite (~220 mAh/g vs. ~330 mAh/g).(1) However, the high surface area, good electrical conductivity and excellent electrochemical stability of HCNS make it a promising support material for other high capacity lithium alloying metals, suggesting the possibility of significantly higher specific capacities, much better low temperature performance and charging rates than graphite-based anodes. Here we present our studies to date on the incorporation of germanium metal which is second only to Si in gravimetric capacity as a Li alloying material (1385 mAh/g) and nearly equal to it in volumetric capacity (7372 mAh/mL), into HCNS anodes.
Syntheses were performed by multiple reduction methods of germanium precursors in the presence of HCNS to produce conductive composites of HCNS. Various Ge morphologies were observed from each synthesis method. Using these composites, electrodes were prepared with different binder materials and tested in different electrolytes at various potentials in attempt to obtain a high capacity, long cycle-life anode while maintaining nearly 100 % coulombic efficiency. A stable capacity of 950 mAh/g of Ge was obtained when cycling from 1.0 to 0.055 V and long-term coulombic efficiency values were greater than 99.7 %. TEM analysis revealed the HCNS particles to be coated with Ge. Performance comparisons of multiple Ge/HCNS composites with differing cycling environments will be presented.
(1) Michael J. Wagner, J. Thomas McKinnon, J. Cox and K. Gneshin, “Hollow Carbon Naonsphere Based Secondary Cell Electrodes”, United States Patent 8,262,942, September 11, 2012.
Sns 2D Nanosheets with High Energy Density for Next-Generation Rechargeable Battery Applications
Authors: Song Kyeongse , Cho Eunbi , Jung Jaepyeong , Kang Yong-Mook 
Published: February 2020

Beyond the human being, economical energy providing/consumption, development of advanced energy conversion system and finding effective way for energy transport are considered as global urgent task which must be accomplished as soon as possible in modern society based on the environmental concerns and climate changes. In this regard, with the purpose of reducing consumption of natural resources as well as decrease of environmental pollution from internal combustion-engine, much effort has been spent on developing new energy storage system (ESS) and electric vehicles (EVs) powered by various batteries, fuel cell and hybrid system. However there are several quite requirements such as high power/energy density of battery, improved safety, and high reliability against with external environmental condition. Even if only considered in power/energy density of battery, state-of-the-art of rechargeable battery system have obvious limit although wide research and development has been conducted to meet requirements for next-generation battery. Therefore, lithium-oxygen batteries and Na ion batteries have engaged intensive attention owing to their high theoretical energy density. Yet, present lithium-oxygen battery and Na ion battery exhibit low efficiency and cyclic degradation, thus limiting their commercialization as next-generation power sources. Therefore, there are many attempts to design tailored materials for as an active material of Na ion battery or catalyst of lithium-oxygen batteries. Among them, metal sulﬁdes have been extensively studied due to their fundamental properties for important technological applications.
Here, we suggest SnS 2D nanomaterials with an unique layered CdI2-type structure with tin atoms sandwiched between two layers of hexagonal close-packed sulphur atoms. Thus, we found that such unique structure is facilitating not only intercalation of Na ions but also have catalytic activity for ORR/OER in lithium-oxygen batteries.
Porous FeF3 Microspheres/Reduced Graphene Oxide Composites as a High Performance Cathode Material for Lithium-Ion Batteries
Authors: Jung Hyeyun , Shin Jihyun , Kim Yonggyeong , Lee Jung Kyoo , Kim Jongsik 
Published: February 2020

Lithium-ion batteries (LIBs) have high energy density, high operating voltage, environmental friendliness and long cycle lifetime. They are applied to the energy storage system such as the mobile phones, laptop computers, and electric-vehicles (EVs). However, modern energy storage device requires the development of LIBs with enhanced reversible specific capacities, which are mainly limited by electrode materials, especially cathode materials. Therefore, it is needed to develop the cathode materials with higher theoretical capacity. FeF3 is of great interest as a potential alternative cathode material for LIBs because of its low cost, abundance, environmental friendliness, and high theoretical capacity of about 237 mAhg−
1 in the voltage range of 2.0−4.5 V and 712 mAhg−
1 in the 1.5−4.5 V, respectively.[1, 2] However, FeF3 has drawbacks of poor capacity retention and rate performance because of its low intrinsic electrical conductivity and slow diffusion of lithium ions.
In this study, porous FeF3 microspheres/reduced graphene oxide (r-GO) composites were synthesized by a simple hydrothermal route with aqueous HF solution. The size of the microspheres was controllable simply by adjusting the amount of the graphene oxide from about 1 to 10 wt% in the precursor solution. The oxygen functional groups of the graphene oxide played a role as an anchoring site for the FeF3 precursor and its crystallization to primary FeF3 nanoparticles, which were structured as a building block to porous FeF3 microspheres. The FeF3 microspheres/r-GO composites showed the improved discharge capacity and cycling stability in the voltage ranges of 1.5-4.5 V and 2.0-4.5 V at room temperature compared to those of bulk FeF3. For example, they delivered an initial discharge capacity of about 195 mAhg-1 at 0.1 C rate with 0.27% fading per cycle during 50 cycles in the 2.0-4.5 V. The composites also showed the significantly enhanced rate capabilities in the range of 0.1-20 C (e.g., about 170 mAhg-1 at 1 C rate). The detailed electrochemical data in the range of 1.5-4.5 V will be presented as well.
References
[1] N. Yamakawa, M. Jiang, B. Key, C. P. Grey, J. Am. Chem. Soc.
2009, 131, 10525.
[2] F. Badway, F. Cosandey, N. Pereira, G. G. Amatucci, J. Electrochem. Soc.
2003, 150, A1318.
Relating Structure to Electrochemistry: I
n-Situ Studies of Fe[Fe(CN)6] As Cathode Materials for Rechargeable Li- and Na-Ion Batteries
Authors: Godfrey Thomas , Schmid Siegbert 
Published: February 2020

The Prussian blue type compound Fe[Fe(CN)6] is investigated as a cathode material for use in rechargeable Li- and Na-ion batteries. The structural changes following electrochemical Li+ and Na+ ion insertion during charge-discharge cycles were followed using in-situ X-ray and neutron powder diffraction techniques.1-3

The electrochemical performance of Fe[Fe(CN)6] has been investigated for both Li+ and Na+ ions with capacities of 100 and 115 mA h g-1 respectively. Further investigations of the Na-ion cells for Fe[Fe(CN)6] show the capacity to depend on the heating temperature used in preparing the cathode material. Fe[Fe(CN)6] heated at 110 °C shows the highest capacity of 115 mA h g-1, with capacity fading to 75 mA h g-1 when the framework is heated at 150 °C. Cells containing samples of Fe[Fe(CN)6] heated at 110 °C show excellent capacity retention of more than 99% after 50 cycles.

In-situ synchrotron X-ray diffraction has been performed for the Na-ion cells, while in-situneutron diffraction studies were carried out on Li-ion cells. In both cases, these allow for the direct correlation of structural changes to the cathode material and the observed electrochemical properties, as both are collected simultaneously.
(1) Roberts, M.; Biendicho, J. J.; Hull, S.; Beran, P.; Gustafsson, T.; Svensson, G.; Edström, K. Journal of Power Sources
2013, 226, 249.
(2) Sharma, N.; Peterson, V. J. Solid State Electrochem.
2012, 16, 1849.
(3) Bergstöm, Ö.; Andersson, A. M.; Edström, K.; Gustafsson, T. J. Appl. Crystallogr.
1998, 31, 823.