bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graphene-Coated Silicon Alloy with High Capacity and Good Cycling Stability for Lithium-Ion Batteries
Authors: Kim Sang-Hyung , Yang Hwi Soo , Yook Seung Hyun , G Kannan Aravindaraj , Kim Seon-Kyong , Park Cheol-Ho , Kim Dong-Won 
Published: February 2020

The growing demand for high-performance energy storage devices for applications in portable electronic devices, electric vehicles and energy storage systems requires dramatic improvement in the energy density and cycle life. Silicon-based anode materials hold promise for these applications due to their high theoretical capacity and abundant availability for large-scale applications. However, silicon anodes are known to have problems such as electrode pulverization due to its high volume expansion during repeated cycling and poor cycle life due to unstable solid-electrolyte interphase (SEI) layer. To solve these problems, many studies have been carried out in terms of thin film, nanostructure, alloy and composites. In this work, we synthesized Si-based alloy materials with high specific capacity. To improve their cycling stability, the silicon alloy materials were surface modified with reduced graphene oxide (rGO). The rGO layer formed on the Si alloy played as a flexible confinement for accommodating volume changes during cycling. And also, its high mechanical strength prevented the pulverization of the electrode. In addition, its 2-dimensional structure enabled to electronically connect the individual Si alloy particles to the current collector. Their interfacial studies and cycling performances are investigated by electrochemical impedance spectroscopy, XPS, FE-SEM, HR-TEM and cycling test. Detailed characterization of the rGO-coated silicon alloy materials along with their electrochemical performance will be presented.
25 Mg NMR Studies of Mg-Ion Battery Materials
Authors: Wang Hao , Sa Niya , Proffit Danielle L. , Senguttuvan Premkumar , Kim Chunjoong , Cabana Jordi , Poeppelmeier Kenneth , Kinnibrugh Tiffany L. , Chapman Karena W , Burrell Anthony K. , Vaughey John T. , Key Baris 
Published: February 2020

Multivalent-ion chemistries such as Mg-ion are emerging as alternative battery systems to Li-ion. Current Mg-ion chemistries are limited to relatively low voltages and relatively low reversible specific capacities (1-2). Recent research on potential high voltage Mg-ion cathode materials and alternative anode materials such as transition metal oxides and metal alloys have highlighted the urgent need to understand structure activity relationships and insertion/intercalation phenomenon for development of such systems (3). Solid state NMR is a powerful tool to investigate local structure and insertion/intercalation phenomena, particularly for batteries as shown for Li-ion chemistries with 6Li and 7Li NMR (4, 5). However, the low natural abundance (10%) of the NMR active Mg isotope (25Mg), highly quadrupolar nuclear spin of 25Mg (spin 5/2) and very low gyromagnetic ratio (i.e 30.6 MHz Larmor frequency relative to 1H = 500 MHz) limits the effective use of 25Mg NMR for solid Mg-ion battery materials (6). In this work, despite the challenges of 25Mg NMR, our recent efforts to characterize Mg environments in cathode materials such as MgMn2O4 spinels, MgV2O5, in anode materials such as h-TiO2 and Mg alloys will be presented. Chemical magnesiation using dibutylmagnesium and preliminary electrochemical (de)magnesiation and the structural changes induced will be discussed. The results will summarize the effectiveness of the method in distinguishing side reactions or undesirable conversion reactions, including amorphous phases, from intercalation phenomenon.
1. D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature,
407 (6805), 724-727 (2000).
2. H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, and D. Aurbach, Energ Environ Sci,
6 (8), 2265-2279 (2013).
3. Magnesium Batteries 1 and 2, 224th Electrochemical Society Meeting, San Francisco CA, 2013
4. C. P. Grey and N. Dupre, Chem. Rev. (Washington, DC, U. S.), 104, 4493 (2004).
5. B. Key, R. Bhattacharyya, M. Morcrette, V. Seznec, J. M. Tarascon and C. P. Grey, Journal of the American Chemical Society, 131, 9239 (2009).
6. R. Dupree and M. E. Smith, Journal of the Chemical Society-Chemical Communications, 1483 (1988).
Electrochemical Reaction Mechanism in a High Capacity Zinc-Ion Battery System
Authors: Alfaruqi Muhammad Hilmy , Gim Jihyeon , Song Jinju , Kim Sungjin , Mathew Vinod , Jo Jeonggeun , Lee Seulgi , Islam Saiful , Kim Jaekook 
Published: February 2020

Earlier efforts to develop an aqueous zinc-ion battery (ZIB), which facilitates energy storage/conversion via Zn-ion intercalation/de-intercalation, has paved the way not only to realizing safe and environmentally benign energy devices, but also to reducing the processing costs of next generation batteries. [1,2] From the viewpoint of developing low-cost and environmentally safe rechargeable batteries that can be easily scaled up for large-scale production, the present study reports on a high surface area mesoporous tunnel-type γ-MnO2 cathode obtained by a simple template-free ambient temperature strategy and subsequent annealing at low temperatures for ZIB applications. An in-depth study on the structural transformation in a mesoporous γ-MnO2 cathode during electrochemical reaction in a zinc-ion battery (ZIB) has been conducted.
A combination analyses of in-situ synchrotron XANES and XRD reveal that the tunnel-type parent γ-MnO2 experiences a structural transformation to spinel-type Mn(III) phase (ZnMn2O4) and two new intermediary Mn(II) phases namely, tunnel-type γ-ZnxMnO2 and layered-type L-ZnyMnO2 and that these phases with multioxidation states co-exist after complete electrochemical Zn-intercalation. On sequential Zn-de-intercalation, a majority of these phases with multi-oxidation states was observed to revert back to the parent γ-MnO2 phase. The mesoporous γ-MnO2 cathode exhibits an initial discharge capacity of 285 mAh g-1 at 0.05 mA cm-2 with a defined plateau at around 1.25 V vs. Zn/Zn2+. Further, ex-situ HR-TEM studies of the discharged electrode aided to identify the lattice fringe widths corresponding to the Mn(III) and Mn(II) phases and the stoichiometric composition estimated by ICP appear to be in agreement with the in-situ findings.

References

C. Xu, B. Li, H. Du, F. Kang, Angew. Chem. Int. Ed., 51, 933, (2012).

C. Yuan, Y. Zhang, Y. Pan, X. Liu, G. Wang, D. Cao, Electrochim. Acta, 116, 404 (2014).
Enhanced Cycling Stability of Hybrid Li-Air Batteries Enabled By Ordered Pd3fe Intermetallic Electrocatalyst
Authors: Cui Zhiming , Li Longjun , Manthiram Arumugam , Goodenough John B. 
Published: February 2020

Hybrid Li-air batteries, in which a solid electrolyte separates the lithium metal anode in an aprotic electrolyte from the air electrode in an aqueous electrolyte, have attracted considerable attention because they possess high theoretical energy density and potentially overcome the problems of conventional aprotic Li-air batteries. However, current hybrid systems still suffer from poor cycling stability. The problem mainly lies in the sluggish kinetics of oxygen reduction reaction (ORR) and poor durability of the cathode catalysts, which actually is also the major limiting factor for other energy conversion and storage technologies such as fuel cells and metal-air batteries. Therefore, it is highly desirable to develop highly active and stable catalysts for the ORR in aqueous media. Herein, we report an ordered Pd3Fe intermetallic catalyst synthesized with a nanoparticle-KCl matrix method. Such structurally ordered phase can provide predictable control over structure, geometric, and electronic effect, not afforded by disordered alloys. Further, as the order in intermetallic phases arises from the high enthalpy of mixing, a higher chemical and structural stability than found in its corresponding disordered alloy can be expected. Our results show ordered Pd3Fe/C catalysts exhibit much higher activity and durability for the ORR in alkaline media than disordered Pd3Fe/C, Pd/C, and Pt/C. The ordered Pd3Fe/C catalyst enables a long-term cycling performance of hybrid Li-air batteries over 880 h with only 0.08 V increase in round-trip overpotential. The extraordinarily high performance of ordered Pd3Fe/C catalyst provides a very promising alternative to the conventional Pt/C catalyst for air cathode in alkaline electrolyte.
Increasing the Capacity Performance in Lithium Metal Secondary Battery By Using Nafion-Coated Cathodes
Authors: Bae Ki Yoon , Kim Byung Hyuk , Yoon Woo Young 
Published: February 2020

Lithium metal has a high theoretical energy density (3860 mAh g-1), which makes it a good anode material for use in secondary lithium batteries. Instead of a lithium-foil electrode, a lithium-powder electrode is used as anode material to prohibit dendrite growth and to improve on the electrochemical behavior[1], [2], When lithium-powder is used directly as a anode electrode, the non-lithiated cathode must have the ability of intercalation and deintercalation of lithium ions.
Lithium trivanadate (LiV3O8, LVO) is a promising non-lithiated cathode material in which lithium ions can inserted and removed from the LVO’s layered structure. LVO is relatively high theoretical capacity (280 mAh g-1) and good cycle stability. However, because of the low conductivities of LVO, the cell exhibits adverse effects in rate retention and degradation during cycle is progressed. Nafion is a well-known cation exchange polymer with high ionic conductivity and excellent stability, which can be coated onto the surface of cathode to solve the LVO’s drawback.
Lithium-powder particles and lithium trivanadate are synthesized by the droplet emulsion technique (DET) and solid-state method, respectively. And Nafion-coated cathode is easily synthesized by using a dip-coating technique. Dip-coating is a facile and fast process, and a simple way to generate a thin uniform film on the surface of LVO[3].
The structure, morphology, and electrochemical properties of lithium metal secondary battery’s electrode were investigated by the implementation of X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and energy dispersive spectroscopy (EDS)[4]. All cells were cycled 50 times at a C-rate of 0.2 and various C-rate with the cut-off voltage ranging from 1.8 to 4.0V (versus Li/Li+). The result was analyzed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV)[5].
As the dip-coating the nafion is performed, layered cathode electrode has higher ionic conductivity. Thanks to effect of coating, lithium-powder/LVO cell appears better electrochemical performance, rate retention in various c-rate and mitigated degradation.
[1] J. S. Kim, W. Y. Yoon, Electrochim. Acta 2004, 50, 531–534
[2] J. H. Chung, W. S. Kim, W. Y. Yoon, S. W. Min, B. W. Cho, J. Power Sources 2006, 163, 191-195
[3] S. J. Oh, J. K. Lee, W. Y. Yoon, ChemSusChem 2014, 7, 2562-2566
[4] D. Wang, L. Cao, J. Huang, J. Wu, Cera. Inte, 38, 2012, 2647-2652
[5] Y.Q. Qiao, J.P. Tu, X.L. Wang, J. Zhang, Y.X. Yu, and C.D. Gu, J. Phys. Chem, 115, 2011 25508-25518
Enabling Rechargeable Magnesium Batteries through Bottom up Design Strategies
Authors: Mohtadi Rana , Tutusaus Oscar , Arthur Timothy S. , Mizuno Fuminori 
Published: February 2020

Recently, rechargeable magnesium battery has been attracting attention as a candidate for a post Li-ion battery owing to a high volumetric capacity of 3832 mAh/ cm3, and the absence of dendrites formation which eliminates a major safety concern hampering the utilization of Li metal anodes [1]. In addition, the abundance and low cost of Mg metal makes this battery very attractive for future commercialization. Nonetheless, current Mg battery technology suffers from several drawbacks which hamper its utilization. These are primarily related to the absence of practical high voltage cathodes and the occurence of severe corrosion of the current collectors caused by the electrolytes. In this presentation, we will explain the current challenges associated with these batteries and offer potential approaches which could be used to overcome these challenges. In addition, we will discuss our electrolyte’s development research strategy using a new class of electrolytes based on magnesium borohydride and its derivatives which resulted in the first simple type, all around and non-corrosive salt that could be used in magnesium batteries [2,3,4,5]. The electrolyte prepared was used in the first demonstration of high voltage Mg battery coin cell making these batteries a step closer to becoming practical [5].
[1] a) H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, D. Aurbach, Energy Environ. Sci. 2013, 6, 2265-2279; b) J. Muldoon, C. B. Bucur, A. G. Oliver, T. Sugimoto, M. Matsui, H. S. Kim, G. D. Allred, J. Zajicek, Y. Kotani, Energy Environ. Sci. 2012, 5, 5941-5950; c) R. Mohtadi, F. Mizuno Beilstein J. Nanotechnol. 2014, 5, 1291–1311.
[2] R. Mohtadi, M. Matsui, T. S. Arthur, S.-J. Hwang, Angew. Chem. Int. Ed. 2012, 51,9780 –9783.
[3] T. J. Carter, R. Mohtadi, T. S. Arthur, F. Mizuno, R. Zhang, S. Shirai, J. W. Kampf,Angew. Chem. Int. Ed. 2014, 53, 3173-3177.
[4] O. Tutusaus, R. Mohtadi, ChemElectroChem. 2014 DOI: 10.1002/celc.201402207.
[5] O. Tutusaus, R. Mohtadi et al. Angew. Chem. Int. Ed. 2015, Accepted.
Materials Design Rules for Multi-Valent Ion Mobility in Intercalation Structures
Authors: Rong Ziqin , Malik Rahul , Canepa Pieremanuele , Gautam Gopalakrishnan Sai , Liu Miao , Jain Anubhav , Persson Kristin A , Ceder Gerbrand 
Published: February 2020

The diffusion of ions in solid materials plays an important role in many aspects of materials science, such as the geological evolution of minerals, materials synthesis, and in device performance across several technologies. For example, the realization of multi-valent (MV) batteries, which offer a realistic route to superceding the electrochemical performance of Li-ion batteries, hinges on the discovery of host materials that possess adequate mobility of the multi-valent intercalant to support reasonable charge and discharge times. This has proven especially challenging, motivating the current investigation of ion mobility (Li+, Mg2+, Zn2+, Ca2+, and Al3+) in spinel Mn2O4, olivine FePO4, layered NiO2, and orthorhombic δ-V2O5. In this study, we not only quantitatively assess these structures as candidate cathode materials, but also isolate the chemical and structural descriptors that govern MV diffusion. Our finding that matching the intercalant site preference to the diffusion path topology of the host structure controls mobility more than any other factor, leads to practical and implementable guidelines to find fast-diffusing MV ion conductors.
Tailored Carbon Nanotubes for High-Performance Lithium-Sulfur Batteries
Authors: Jeong Yo Chan , Yang Seung Jae , Lee Kunsil , Kim Taehoon , Kim Jae Ho , Jung Haesol , Cho Young Shik , Park Chong Rae 
Published: February 2020

Significant effort has been invested into addressing critical problems of lithium-sulfur batteries since they are considered as the next generation energy storage material due to their high specific energy density and low cost.1 Critical problems still remain including poor cycle life and rate capability originated from the insulating nature of sulfur and polysulfide intermediate dissolution into the electrolyte.2 Despite the considerable success in alleviating the problems such as drastic capacity fading and poor rate capability, commercial application still has a long way to go, especially at high current rate conditions.
Here, we report a noble carbon matrix for lithium-sulfur batteries based on a partially unzipped multi-walled carbon nanotube(MWCNT) with favorable properties for the improved lithium-sulfur batteries. Partially unzipped MWCNT has additional benefit in that it was prepared by facile and scalable way without use of toxic or expensive materials. In contrast to MWCNT and fully unzipped nanoribbon, partially unzipped MWCNT clearly exhibited a unique structure of coexistence of carbon nanotube and nanoribbon in one tube as illustrated in Figure 1. The experimental optimization results were fully discussed with TEM, SAED patterns, EDS mapping, RAMAN, XPS, BET isotherms and EIS characterizations.
Partially unzipped MWCNT showed increased surface area and pore volume with preserved electron conductive pathway owing to opened inner pores of MWCNT. Newly developed the pores of partially unzipped MWCNT were decorated with oxygen containing functional groups and acted as a stable polysulfide reservoir as illustrated in Figure 2. The synergistic effect of unique pore structure and oxygen containing functional groups led to the improved electrochemical performance at a high current rate of 8375 mA g-1 (5 C). Partially unzipped MWCNT-sulfur composite delivered 688.5 mAh g-1 at the initial discharge and retained 544.2 mAh g-1 after 100 cycles at the high current rate of 5 C as given in Figure 3.
Furthermore, to understand the mechanism of the improved electrochemical performance of partially unzipped MWCNT, Partially unzipped MWCNT-sulfur was studied utilizing the Monte Carlo (MC) simulations. This modelling explains why the polysulfide dissolution into the bulk electrolyte was alleviated thus led to the improved electrochemical performance.
We believe that our work can provide insight to many researchers in that partially unzipped MWCNT opens up a new concept of exploiting MWCNT inner pores.

Reference

1. Chung, W. J.; Griebel, J. J.; Kim, E. T.; Yoon, H.; Simmonds, A. G.; Ji, H. J.; Dirlam, P. T.; Glass, R. S.; Wie, J. J.; Nguyen, N. A. et al. The use of elemental sulfur as an alternative feedstock for polymeric materials. Nat. Chem. 2013, 5, 518-524.
2. Manthiram, A.; Fu, Y.;Su, Y.-S. Challenges and Prospects of Lithium-Sulfur Batteries. Acc. Chem. Res. 2012, 46, 1125-1134.

Figure 1
Understanding Li-S Chemistry with First-Principles Analysis
Authors: Balbuena Perla B , Burgos Juan Carlos , Ma Yuguang , Camacho-Forero Luis Eduardo , Smith Taylor , Bertolini Da Silva Oliveira Samuel 
Published: February 2020

Fulfilling the promise of Li-S batteries depends on the implementation of strict controls on the degradation processes that are involved in a strongly correlated system. A highly reactive Li anode requires of a special electrolyte formulation able to control dendrite formation and its subsequent effects on the cell performance. In addition, the presences of soluble polysulfides (PS) that travel from cathode to anode substantially change the anode interfacial chemistry. On the other hand, intimately mixed sulfur-carbon cathode formulations are usually employed to enhance the cathode electronic conductivity. As a consequence, sulfur reduction reactions at the cathode interface are affected by the presence of porous carbon structures. Thus, a complex chemistry requires of numerous tools to identify processes and mechanisms with the goal of guiding improvements in materials aimed to extended battery life. Among these tools, first-principles density functional theory and ab initio molecular dynamics simulations yield information regarding molecular mechanisms that is not readily available or difficult to obtain from experimentation. Here we focus on two aspects: interfacial electrolyte decomposition reactions on the Li anode surface leading to the initial stages of the solid-electrolyte interphase (SEI), and sulfur reduction at the cathode. We study the reduction mechanisms of a series of electrolyte solutions including 1M solution of Lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) in pure solvents such as Dioxolan (DOL), 1,1,2,2-Tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (D2), dimethoxyethane (DME), and ethylene carbonate (EC) and mixtures of DOL/DME, and DOL/D2. The reduction mechanisms of soluble PS species such as S8Li2, S6Li2 and S4Li2 at the anode surface are also investigated, along with their effect on the electrolyte decomposition reactions. At the cathode side we characterize discharge reactions and their voltage profiles for sulfur reduction in contact with the electrolyte, versus sulfur reduction in contact with carbon and the electrolyte. Also we analyze effects of carbon structure on diffusion and dissolution of sulfur anions and PS species as well as on Li2S precipitation.
(Invited) Epitaxial III-Nitride Film Growth in a Single Wafer Rotating Disk MOCVD Reactor
Authors: Papasouliotis George D , Su Jie , Krishnan Balakrishnan , Arif Ronald 
Published: February 2020

Epitaxy of GaN on large-size Si wafers can enable the adoption of AlGaN-based High Electron Mobility Transistors (HEMTs) in a broad range of applications ranging from consumer electronics, solar and wind power, power supplies, and automotive, to the potential integration with Si-based CMOS technologies. Device performance dictates stringent requirements for epitaxial film quality and uniformity, while wafer bow management during growth facilitates the use of larger diameter substrates. Uniform temperature profile and gas distribution in the MOCVD reactor become critical elements for film performance and, ultimately, technology adoption. In this work, we are reporting on the epitaxy of Al/Ga/N containing films on 200 mm Si wafers. The TurbodiscÒ, vertical, rotating disk reactor used for epitaxy encompasses the fundamental reaction and high velocity laminar flow characteristics of its predecessor batch systems, thus enabling stable, repeatable operation, long PM cycles, and direct, model-based process scale up. Moreover, it incorporates advanced features, which will be discussed, for alkyl/hydride flow distribution and temperature uniformity, which translate into excellent uniformity in epitaxial layer thickness, alloy composition, and doping profile across the wafer. Results on AlGaN/GaN heterostructures, thickness uniformity of GaN 0.48%, 1σ, and AlN 0.86%, 1σ, Al composition uniformity in AlGaN of 0.289%, 1σ, and 2DEG performance are presented. Uniform incorporation of dopant species (Mg and C) across the substrates is reported. The average Hall mobility is > 1700 cm2/V.s, with sheet carrier concentration at 9.5x1012/cm2, and sheet resistance 380 Ohm/sq for the 5 points across the wafer. Results on the repeatability of film quality, FWHM of GaN (002) and (102) showing < 1.5% 1σ over 20 runs, and average Al composition of AlGaN barrier, showing variation of 0.37 % 1σ over 16 runs, are presented. Wafer bow can be precisely engineered and controlled through the thickness and composition of the stress compliance structure.
(Invited) Lead Halide Perovskite Nanowire and Nanoplate Lasers with Low Lasing Thresholds and High Quality Factors
Authors: Jin Song 
Published: February 2020

The remarkable performance of lead halide perovskites in solar cells can be attributed to the long carrier lifetimes and low non-radiative recombination rates, the same physical properties that are ideal for semiconductor lasers. Here we first report new insights on the crystal growth of the perovskite materials and the solution growth of single crystal nanowires, nanorods, and nanoplates of methylammonium lead halide and other perovskites via a dissolution-recrystallization pathway from lead iodide or lead acetate films coated on substrates. We further show room temperature and wavelength tunable lasing from single crystal lead halide perovskite nanowires with the lowest lasing thresholds (220 nJ/cm2) and highest quality factors (Q ~ 3600) reported to date for semiconductor nanowire lasers. The lasing threshold corresponds to a charge carrier density as low as 1.5×1016/cm3. Kinetic analysis based on time-resolved fluorescence reveals little charge carrier trapping in these single crystal nanowires and gives estimated lasing quantum yields approaching 100%. Such lasing performance, coupled with facile solution phase growth of single crystal NWs and broad tunability of emission color from stoichiometry, makes lead halide perovskites ideal materials for the development of nano-photonics, in parallel with the rapid development in photovoltaic technology from the same materials.