bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anomalous Voltage Change in Charge and Discharge Curves for Electrode Materials Showing Plateau-like Behavior
Authors: Herrmann Matthias , Richter Frank , Riegel Bernhard 
Published: February 2020

Recently T. Sasaki et al.
1 reported on a phenomenon of an anomalous voltage change that occurs when electrode materials showing a plateau-like behavior (during charge/discharge) are partially charged and/or discharged. They studied the anomalous voltage change in lithium iron phosphate (LiFePO4) as well as in lithium titanate (Li4Ti5O12). The anomalous voltage change was referred to as ‘voltage bump’ which appears already after only one cycle of partial charge and discharge. The voltage bump was explained in connection to a particle-by-particle charge/discharge model. The reported electrochemical tests were performed at room temperature in two-electrode coin-type or three-electrode cells with Li-metal as reference and counter electrode (half cell).
In this work, partial charge/discharge experiments (Fig. 1) were used to study the effect of temperature on the anomalous voltage change. The investigations were carried out on commercially available large-format cells based on LiFePO4/graphite system (full cell). Increasing the number of partial cycles leads to an interference of single voltage bumps, but the voltage rise was observed to saturate at a given voltage level (Fig. 2). An increased voltage bump was observed at smaller temperature, while an opposite effect was obtained at higher temperature (Fig. 2). Resulting voltage bumps in the range of up to 20 mV were observed, depending on temperature. The observed behavior is discussed in view of the particle-by-particle model and kinetic effects. Such a slight voltage change can lead to substantial miscalculations in estimating the state of charge of cells and batteries.

1Tsuyoshi Sasaki, Yoshio Ukyo, Petr Novák, Nature Materials, published online: 14 April 2013, DOI: 10.1038/NMAT3623.
Electrical Explosion Synthesis of Si/C Nanocomposites for Li Secondary Batteries
Authors: Kim Doohun , Ha Yoon-Cheol , Cho Chuhyun , Lee Won-Jae , Doh Chil-Hoon 
Published: February 2020

A novel technique of electrical explosion has been used for nanomaterial synthesis by a single-step process [1-5]. However, it was known that in principle the electrical explosion of Si is not possible due to the fact that applying a high voltage on Si wire having relatively high electrical resistance leads to a current flow through surface plasma formed along the wire which disables the resistive heating of Si. In this presentation, we will show the successful application of electrical explosion to silicon nanoparticle synthesis and the electrochemical properties of Si/C nanocomposites derived from the nanoparticles.
The electrical explosion of Si was successfully applied using a liquid media to suppress the unfavorable surface plasma generation. The physical and chemical properties of the produced materials were analyzed by XRD, FE-SEM, HR-TEM and the performances of the Si/C composites as an anode for Li ion batteries were investigated by electrochemical charge/discharge measurements. The Si/C composites obtained under the explosion in hexane and ethanol consist of a core-shell structure with a compact graphitic carbon on the Si particle surface which cause detrimental effects against Li ion diffusion. However, we found that Si explosion in methanol minimized the formation of the carbon phase on the surface of nano-sized Si. The Si/C nanocomposite after a simple pyrolysis with carbon precursor showed a high capacity with an excellent cycle performance.
[1] Cho, C., Choi, Y.W., Kang, C., Lee, G.W. Effects of the medium on synthesis of nanopowders by wire explosion process (2007) Applied Physics Letters, 91 (14), p. 141501.
[2] Cho, C., Ha, Y.-C., Kang, C., Jin, Y.-S., Rim, G.-H. Preparation of a nickel nanopowder by wire explosion in liquid media (2010) Journal of the Korean Physical Society, 57 (61), pp. 1807-1810.
[3] Ha, Y.-C., Cho, C. Production of highly-dispersed nano-sized Sn powders in a liquid medium by using a high-energy electrical explosion (2010) Journal of the Korean Physical Society, 57 (61), pp. 1574-1576.
[4] Cho, C., Ha, Y.-C., Kang, C., Jin, Y.-S., Rim, G.-H. Electrical explosion of silicon rod in distilled water (2011) Japanese Journal of Applied Physics, 50 (10 PART 1).
[5] Ha, Y.-C., Kang, C., Cho, C., Kim, Y.-U., Park, C.-M., Sohn, H.-J. Wire explosion synthesis of a Sn/C nanocomposite as an anode material for Li secondary batteries (2011) Journal of the Korean Physical Society, 59 (61), pp. 3458-3462.
High Voltage Na3V2O2x(PO4)2F3-2x (0≤x≤1) Positive Electrode Materials for Na-Ion Batteries
Authors: Serras Paula , Palomares Veronica , Alonso Javier , Sharma Neeraj , Lopez del Amo Juan Miguel , Kubiak Pierre , Fernandez-Gubieda María Luisa , Rojo Teofilo 
Published: February 2020

Sodium-ion batteries have arisen as good candidates to become alternative systems that could complement commercial Li-ion systems [1]. The use of Na instead of Li in rocking chair batteries could mitigate the possible shortage of lithium in an economical way. For this purpose, the search for commercially viable Na-ion batteries demands finding and optimizing new electrode materials and electrolytes.
Among the possible cathodic materials, the family of compounds Na3V2O2x(PO4)2F3-x (Fig. 1) presents high operating voltages and specific capacity values, which are key parameters to get a high energy density battery [2]. In this study, two sodium-vanadium fluorophosphate materials were prepared:
- Carbon-free and carbon-coated Na3V2O2(PO4)2F phase (x = 1), where vanadium oxidation state is V4+.
- A mixed valence V3+/V4+ carbon-coated material belonging to the Na3V2O2x(PO4)2F3-2x family where 0 ≤ x ≤ 1.
Structural characterization of the composites was performed by powder X-ray diffraction (XRD). A double titration method as well as 23Na and 19F NMR measurements were necessary for the determination of the oxidation state of the vanadium. The morphology of the materials was analyzed by Scanning Electron Microscopy (SEM). The electrochemical measurements were conducted using Swagelok-type cells versus a metallic sodium anode. Ex-situ XRD and XANES data of electrodes charged and discharged at selected voltages allowed to deeper study the structural evolution of the material during cycling.
The two investigated compounds show similar electrochemical features such as high operating voltages (3.6 and 4.1 V vs. Na/Na+) and a high theoretical specific capacity (about 130 mAh/g). However, some differences can be observed in the potential vs. capacity curves (Fig. 2). A comparison between the up-to-date literature data [3,4] and the electrochemical data obtained from both the mixed valence and V4+materials will be established. The relationships composition-structure-electrochemical behaviour will be presented in detail and discussed.
[1] V. Palomares, P. Serras, I. Villaluenga, K.B. Hueso, J. Carretero-González and T. Rojo Energy and Environ. Sci. 5 (2012) 5884.
[2] P. Serras, V. Palomares, A. Goñi, I. Gil de Muro, P. Kubiak, L. Lezama and T. Rojo J. Mater. Chem. 22 (2012) 22301.
[3] K. Chihara, A. Kitajou, I. D. Gocheva, S. Okada, J-I Yamaki J Power Sources, (2012) doi: 10.1016/j.jpowsour.2012.10.034.
[4] R. A. Shakoor, D-H Seo, H. Kim, Y-U Park, J. Kim, S-W Kim, H. Gwon, S. Leec and K. Kang .J. Mater. Chem. 22 (2012) 20535.
Preparation and Electrochemical Performance of Mo6V9O40 Nanorods as Cathode Materials for Li-Ion Batteries
Authors: Hu Meng , Wei Jinping , Zhou Zhen 
Published: February 2020

Searching for cathode materials for Li ions batteries with high energy density is a key mission in recent years [1]. Among various candidates, vanadium and molybdenum oxides have been intensively studied due to their high capacity, easy preparation, and low cost. For example, Li ions can reversibly intercalate/deintercalate into the lattice layers of V2O5 and MoO3. Their hybrid oxides, molybdenum-vanadium based oxides, have been reported to be more sustainable to over discharge (to 1.5 V vs. Li/Li+), including solid solution (V1
-
yMoy)2O5 (0≤y≤0.3) and Mo6V9O40 [2]. Introduction of Mo into the structure increases the M-O bond length, and the structure is more flexible for Li ion intercalation/deintercalation. In addition, substituting Mo6+ for V5+increases the electronic conductivity [3].
Pure-phase molybdenum and vanadium mixed oxides are difficult to be obtained due to the multiphase equilibrium. Extremely long annealing time at high temperatures (above 600ºC) is needed to eliminate the impurity phases (such as V2O5 and MoO3). However, long time at high temperatures results in large particles, which degrades the electrochemical performance and is unfavorable for large-scale production. In this work, Mo6V9O40 nanorods with the diameters of ~200 nm were prepared through a sol-gel route, and the calcining time decreased to 2 h. The Mo6V9O40 nanorods exhibited an initial discharge capacity of 369 mA h g-1 at a current density of 100 mA g–1, and Li+ intercalation is partly irreversible, which is similar to V2O5. The discharge capacities of the second cycle were 276.2 and 212 mA h g-1 at 100 mA g–1 and 1 A g–1, and retained 214.8 and 181.8 mA h g-1after 50 cycles, exhibiting good cyclic stability and rate performance.

Figure 1. (a) SEM, (b) TEM, (c) charge/discharge curves at 100 mA g–1, and (d) cyclic performance at 100 mA g–1 and 1 A g–1 of Mo6V9O40nanorods.

References

[1] M. Hu, X. Pang, Z. Zhou, J. Power Sources 237 (2013) 229-242.
[2] A. Tranchant, R. Messina, J. Power Sources 24 (1988) 85-93.
[3] M. Uchiyama, S. Slane, E. Plichta, M. Salomon, J. Electrochem. Soc. 136 (1989) 36-42.
Flexible, Free Standing Integrated Conductive Network/Current Collector Organic Radical Polymer Electrode
Authors: Xie Jingying , Dai Yang , Cai Sendan , Yang Weijing 
Published: February 2020

Organic radical batteries (ORBs) are emerging as high-rate capable, designable, environmentally friendly, and promising power for thin film batery. An ORB is composed of at least one of its electrodes based on radical polymer or organic radical as the active material. The first report of ORB was by Nakahara et al. in 20021.The n-type radical polymer can serve as the anode active material, while the p-type radical polymer, which usually bearing repeating units of nitroxide radicals, can be employed as the cathode active material. The charging process of the p-type radical polymer based cathode corresponds to the one-electron oxidation of the nitroxide radicals to the oxoammonium cations, with electrolyte anions providing the counter-charge. Upon discharge, the reverse processes occur.
However, the organic radical polymer electrode suffers from low energy density because of the low electronic conductive of the active polymer material, leading to require a lot of conductive carbon (>60 wt%) should be added to the electrode fabrication. In order to improve the energy density of the radical polymer electrode, we develop a new conducting network/current collector integrated electrode.
The electrode possesses higher energy density (active material > 50 wt%), flexible and free standing, that is quite promising for thin film battery application. The results and details will be presented in the meeting.
This work was supported by National Natural Science Foundation of China (No. 21103109, No. 21373137), Shanghai Science and Technology Talent Program(No. 12XD1421900).

Reference

K. Nakahara et al Chem. Phys. Lett. 359, 351 (2002).

T. Katsumata et al Macromolecules 41,1175 (2008).
Substitution Chemistry of Li2MSiO4: A Highly Flexible Framework
Authors: Armstrong Anthony Robert , Billaud Juliette Marie , Adamson Paul , Eames Christopher , Islam M. Saiful , Bruce Peter G. 
Published: February 2020

Lithium transition metal silicates, Li2MSiO4(M=Fe, Mn, Co)[1], have attracted a lot of interest recently as positive electrodes for Li-ion batteries due to their potentially high theoretical capacities and to their rich crystal chemistry as they undergo complex polymorphism. One of the drawbacks of the silicates is their modest rate capability, particularly at room temperature. The present work addressed this problem.
The polymorphs of Li2MSiO4can be classified into low (β) and high (γ) temperature forms, which differ in the ordering/distribution of cations within tetrahedral sites of an hcp based packing of oxygen. β forms exhibit only corner sharing and γ polymorphs both corner and edge sharing. It has been shown by us and by others that Li2FeSiO4 exists in at least 3 different polymorphic forms and that. in the case of Li2MnSiO4two stable polymorphs are observed [1-3].
The silicates are analogous to the LISICON materials (Lithium SuperIonic Conductors), of the form Li2+2xZn1-xGeO4, which adopt the γ structure with interstitial and highly mobile lithium. Therefore, stabilization of the γ polymorph to room temperature represents a potentially attractive route to enhancing the rate performance thus overcoming one of the major barriers to adoption of Li2MSiO4 cathodes.
With appropriate substitutions we have been able to stabilise the γ polymorph for both Li2FeSiO4 and Li2MnSiO4systems. We will report the effects on structure and electrochemistry of the various substitutions. In the iron system good cycling stability and improved rate capability are observed (fig. 2).
References

[1] a) A. Nytén, A. Abouimrane, M. Armand, T. Gustafsson and J.O. Thomas, Electrochem. Comm., 7, (2005) 156; b) M. S. Islam, R. Dominko, C. Masquelier, C. Sirisopanaporn, A. R. Armstrong and P. G. Bruce, J. Mater. Chem., 21 (2011) 9811.
[2] S. I. Nishimura, S. Hayase, R. Kanno, M. Yashima, N. Nakayama, A. Yamada, J. Am. Chem. Soc., 130 (2008) 13212.
[3] C. Sirisopanaporn, A. Boulineau, D. Hanzel, R. Dominko, B. Budic, A. R. Armstrong, P. G. Bruce, C. Masquelier, Inorg. Chem., 49 (2010) 7446.
Synthesis of Nanostructured TiNb2O7 Anode: High Capacity and Improved Rate Performance for Lithium Ion Battery Applications
Authors: Jo Changshin , Chun Jinyoung , Lee Jinwoo 
Published: February 2020

Titanium-based materials have been regarded as promising alternatives to carbon-based electrode materials due to their high-voltage lithium insertion processes using a Ti4+/Ti3+ redox couple (~1.5 V vs. Li/Li+). Within this high voltage region (> 1V), the electrode is safe from the formation of solid-electrolyte interphase (SEI) and a lithium dendrite formation, thus guaranteeing a stable cycle performance and fast charging/discharge performance. However, the most negative point of the anode using the Ti4+/Ti3+ redox couple is their theoretically low charge capacities (Li4Ti5O12: 175 mA h g-1 and anatase TiO2: 168 mA h g-1).
As a new electrode material, TiNb2O7 (TNO) was reported by Goodenough’s group in 2011. This material can insert 5 Li ions due to the multiple redox couples (Ti4+/Ti3+, Nb5+/Nb4+, and Nb4+/Nb3+), corresponding to a high theoretical capacity of 387.6 mA h g-1. This value is much higher than that of other Ti- and Nb-based electrodes. However, due to the high formation temperature of monoclinic TNO phase, it was hard to synthesize nano-sized or nano-structured TNO materials. Above 900 °C, primary particles grow to a large size, in the order of 100 nm. Therefore, an effective fabrication method for the nanosized TNO crystals is necessary in order to achieve rapid Li storage, as in the case of other electrode studies.
In this presentation, we report the synthesis of an ordered mesoporous structured TiNb2O7 (OM-TNO) and its high capacity and rapid rate performance as an anode in LIB. The OM-TNO was synthesized using block-copolymer-assisted, one pot synthesis. As a structure-directing agent, Poly (ethylene oxide-b-styrene) interacts with the hydrolyzed Ti- and Nb-sol, resulting in a segregation of PS blocks and PEO/precursors. After heat-treatment at 900 °C, nano-sized TNO crystals are formed inside the pore walls. As an anode, OM-TNO electrode exhibited high reversible capacity of 289 mA h g-1 at a 0.1 C rate, and high rate capability; 40% capacity retention at a 50 C rate (= 19.35 A g-1). The enhanced electrochemical performance is attributed to the OM-TNO’s unique features, such as the small crystallites, large mesopores, and high surface area.
A Study of the Effect of Graphite Surface Properties on the Cycle Life of Lithium Ion Battery By the Analysis of SEI Layer
Authors: Kwon Se Man , Oh Seh Min , Park Yong Tae , Kim Byoung Ju , Kang Sung , Park Sei Min 
Published: February 2020

Much work has described the influence of anodic SEI (Solid Electrolyte Interphase) on the cycle stability of a lithium secondary battery. Especially, it was reported that the characteristics of SEI Layer were greatly affected by the crystallographic and chemical properties of graphite. The purpose of this study was the identification of the effect of functional groups of graphite on the chemical composition and distribution of SEI Layer. Also the correlation between the SEI film properties and cycle life of battery was investigated through the analysis of composition and distribution of the components that constitute the SEI film.
Two kinds of commercial natural graphite active materials prepared by different surface modification process were used for the comparison of the functional groups. These active materials were manufactured as powders by POSCO-Chemtech (PCT-H, PCT-3). The PCT-H was modified by surface reforming process, and PCT-3 was fabricated from the graphitization of natural graphite with carbon layer of surface.
With these anode materials, the cyclic test was performed using 2032 - typed coin cell.
After 300th cycle, the anode was isolated from coin cell to inhibit the chemical change of SEI layer. XPS and TEM-EELS analyses on the anode were followed for the comparison of the characteristics under inert atmosphere.
In this work, It was found that the modification method of graphite strongly Influenced on the SEI layer. Therefore, this result can be utilized to improve the compatibility of the anode to the electrolytes.
Electrolytes Beyond the State of the Art for Rechargeable Magnesium Batteries
Authors: Mohtadi Rana , Mizuno Fuminori , Arthur Timothy S. 
Published: February 2020

Recently, rechargeable magnesium batteries have been attracting an increased attention as a candidate for a post Li-ion battery owing to a high volumetric capacity (3833 mAh cm-3 vs. 2046 mAh mAh cm-3 for Li) , absence of dendrites formation and the lower cost of Mg metal (about 10 times cheaper than Li). Nonetheless, current Mg battery technologies suffer from several drawbacks which hamper reaching its full potential. For example, the absence of robust and practical high voltage/high capacity cathodes currently limits the energy density which could be harnessed using these batteries.[1] Another major challenge relates to the electrolytes used in magnesium batteries. Current state of the art electrolytes use Grignard/organohalo magnesium reagents and complexes since electrolytes based on conventional inorganic and ionic Mg salts were found to passivate the Mg metal surface. [1] These organohalo reagents, while possessing an impressive electrochemical performance, were found to cause corrosion to the metallic battery parts such as current collectors. This corrosive nature has been linked to the presence of the chloride ion which is an integral part of the electrolytes’ make. Therefore, a new strategy for designing electrolytes for magnesium batteries is highly desired. We have been pioneering the development of a new class of electrolytes that are based on borohydrides salts. These represent the first and only example of an inorganic, relatively ionic and halide free salts reported to date that are compatible with Mg metal. [2] These electrolytes were used in the first rechargeable Mg battery utilizing an inorganic salt leading to opening a new dimension in the design space of magnesium battery electrolytes. Here, we will explain our design strategies, discuss fundamental properties obtained from systematic spectroscopic and electrochemical studies and share up-to-date results related to these new promising systems.
References
[1] H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, D. Aurbach, Energy Environ. Sci. 2013, 6, 2265-2279.
[2] R. Mohtadi, M. Matsui, T. S. Arthur, S.-J. Hwang, Angew. Chem. Int. Ed. 2012, 51, 9780 –9783.
Enhanced Performance of Li-S Battery with Self-Assembled Polypyrrole Film As a Functional Interlayer
Authors: Ma Guoqiang , Wen Zhaoyin , Jin Jun , Wang Qingsong 
Published: February 2020

Lithium sulfur batteries are attracting increasing attentions in recent years due to their high theoretical capacity of 1675 mAh.g-1, low cost, natural abundance and environmental friendliness. However, a rapid capacity fading hinders their practical application, which is attributed to the high insulating nature of sulfur, the dissolution of lithium polysulfides and volume expansion[1, 2]. In this work, as schematically illustrated in Fig.1a, a self-assembled polypyrrole (PPy) films composing of PPy nano-wires and PPy nano-tubes are sandwiched between sulfur cathode and separator of Li-S cell to act as functional interlayer in attempt to alleviate the polarization of sulfur cathode and to suppress the shuttle effect.
Fig.1 TEM images of PPy nano-wires and PPy nano-tubes, and a schematic cell configuration of rechargeable Li-S batteries with PPy interlayer (a). Initial charge/discharge profiles (b), Nyquist plots measured before cycling (above) and after 100cycles at 0.2C (below) (c), cycle performance and coulombic efficiency of Li-S batteries with PPy nano-wire interlayer, PPy nanotube interlayer and without interlayer(d).
As shown in Fig.1b, the Li-S battery with PPy interlayers shows higher discharge plateaus and lower charge plateaus than the cell without interlayer, indicating a decreased polarization. Moreover, both the typical valley at the end of the first discharge plateaus and a peak at the beginning of the charge profile for Li-S cell disappear for the cell with PPy interlayers. Fig.1c shows evidently decreased resistance of the cells with PPy interlayer, indicating that the interlayer acts as a pseudo-upper current collector which reduces the effective resistance of the highly insulating sulfur cathodes and enhances the utilization rate of the active material. Furthermore, the cycle performance and coulombic efficiency of the cells with PPy nano-wire and PPy nano-tube interlayers are much better than the cell without interlayer. The positive effect of PPy interlayer could be ascribed to the strong adsorption effect between PPy and lithium polysulfides[3] which can inhibit the migration of lithium polysulfides effectively and thus improve the coulombic efficiency and cycling stability. As seen in Fig.1d, the discharge capacities of Li-S batteries with PPy nano-wires interlayer and PPy nano-tube interlayer are maintained at 782mAh.g-1 and 687.5mAh.g-1 after 200 cycles respectively, which are much higher than the cell without interlayer (476mAh.g-1after 100 cycles).

References

[1] S.A.F. Peter G. Bruce, Laurence J. Hardwick and Jean-Marie Tarascon, Nat Mater, (2012) 11,19-29.
[2] Y. Yang, G. Zheng, Y. Cui, Chem Soc Rev, 42 (2013) 3018-3032.
[3] W. Li, Q. Zhang, G. Zheng, Z.W. Seh, H. Yao, Y. Cui, Nano Lett, 13 (2013) 5534-5540.