bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tin Oxide Anchored on Reduced Graphene Oxide Sheet to Provide Improved Electrochemical and Structural Properties for Alkali Ion (Li, Na) As an Anode Material for Rechargeable Battery
Authors: Jo Chang Heum , Jo Jae Hyeon , Myung Seung-Taek 
Published: February 2020

Lithium secondary batteries have played important roles as energy storage and conversion devices EV(electric vehicle) and ESS(energy storage system). In this respect, improvement of electrodes is being progressed towards ensure long cycling performances, stability, safety, and so on. For anode materials, in particular, conversion reaction materials need to be further developed because alloy and conversion reaction enabled high capacity delivery though the cyclability should be improved. However, severe volume expansion impedes the utilization of those electrode materials in commercial batteries. Tin oxide is composited with rGO to ensure structural and cycle stability in both lithium and sodium systems.
In this study, we synthesized SnO2 nanoparticle was anchored on rGO sheet by layer by layer self-assembly method. For synthesize SnO2 nanoparticle, we used hydrothermal method. To confirm the physical and electrochemical properties, XRD, SEM, TEM, RAMAN, galvanostatic test. The synthesized SnO2 and rGO/SnO2 had same crystal structure and particle size was about 10-20nm. Both materials exhibited high charge capacity of about 1000mAh/g and much improved rate capability was achieved by rGO sheets in Li cell. Similarly, much improved electrochemical properties were found for SnO2/rGO composite in Na cells as well.
It is thought that rGO sheet assisted electro chemical stability by their 2D network during repetitive volume expansion.
Hierarchically Porous and Heteroatom Doped Carbon Host Matrix for Long Life Li/S Battery: A Mechanistic Investigation By in-Situ Raman Spectroscopy and Ex-Situ XPS
Authors: Vinayan Bhaghavathi Parambath , Fichtner Maximilian 
Published: February 2020

Lithium-sulfur (Li/S) batteries are considered as one of the promising rechargeable battery technology due to their low cost, ecofriendly and high theoretical energy density (~2500 Whkg-1).1, 2 The high theoretical specific capacity (~1672 mAh g-1) of Li/S battery is the result of reversible two electron conversion reactions between sulfur and lithium (S8 + 16Li+ + 16e− ↔ 8Li2S) at an average voltage of 2.1 V with respect to Li/Li+ and finally form solid lithium sulfide (Li2S) through a series of intermediate liquid polysulfides.2, 3 The physiochemical properties of the carbon host matrix and their sulfur loadings at the cathode side play a major role in the electrochemical performance of lithium-sulfur (Li/S) batteries. We have designed a highly sulfur loaded (~ 75 wt. %) carbon matrix (S/NGC), with hierarchically organized micro/meso pore structures and containing nitrogen and oxygen functional groups, using metal oxide nano templates. The S/NGC electrodes give the reversible capacities of 868 and 666 mAh g-1 at C/5 current rates, with the sulfur loadings of 2.2 and 3.4 mgSulfur cm-2, respectively. Based on the advantages of the hierarchical porous structure and nitrogen doping, S/NGC electrode gives a long cycling stability (0.03% capacity decay per cycle up to 1000 cycles) and very good coulombic efficiency (Fig. 1a). Further, the charge/discharge mechanism of the cell is investigated in detail by insitu Raman spectroscopy (Fig. 1b) and ex-situ X-ray photoelectron spectroscopy (XPS). In-situ Raman spectroscopy analysis of the Li/S cell shows the formation of short chain polysulfides (S3
.-, Li2Sx, x = 4-1) already at higher discharge potentials (> 2 V).The presence of nitrogen on carbon support is found to enhance the bonding between sulfur and oxygen functional groups present in the carbon support, which is supposed to take a major role in the prevention of sulfur/polysulfides species dissolution to anode side.

References

1. Y. V. Mikhaylik, I. Kovalev, R. Schock, K. Kumaresan, J. Xu and J. Affinito, ECS Transactions, 2010, 25, 23-34.
2. L. F. Nazar, M. Cuisinier and Q. Pang, MRS Bulletin, 2014, 39, 436-442.
3. P. G. Bruce, S. A. Freunberger, L. J. Hardwick and J.-M. Tarascon, Nat Mater, 2012, 11, 19-29.

Figure 1
Electrochemical Properties of Birnessite As a Positive Material for Aqueous Calcium-Ion Batteries
Authors: Hyoung June E , Hong Seung-Tae 
Published: February 2020

Recently, calcium-ion batteries (CIBs) have received attention as a candidate for next generation batteries due to slight difference of standard reduction potential about 0.17 V above that of lithium and relative abundance of calcium compared to lithium.1 It is known that the birnessite-type manganese oxide, characterized by a layered structure consisting of edge-shared MnO6 octahedral with interlayer distances of ~7 Å as shown in Fig. 1a, allows high mobility of the interlayer cations of lithium or sodium with fast kinetics and little structural rearrangement.2 In this study, the electrochemical properties of the birnessite have been investigated as a cathode candidate material for rechargeable aqueous CIBs.
The birnessite was synthesized by thermal decomposition of KMnO4 according to the previous report.3 The working electrodes consisted of the active material (birnesstie), conducting carbon (super P), and binder (polyacrylonitrile) with the weight ratio of 80:10:10. Activated carbon and Ag/AgCl were served as the counter and the reference electrode, respectively. The galvanostatic discharge/charge experiments were carried out at C/10 in the voltage range of -0.4­ – 0.8 V vs. Ag/AgCl in 1.0 M Ca(NO3)2 aqueous electrolyte. Reversible calcium-ion intercalation was observed in the electrolyte system as shown in Fig. 1b, c. The initial discharge/charge capacities were 182 mAh g-1 and 151 mAh g-1, respectively. The average discharge voltage was estimated to be around 2.8 V vs. Ca2+/Ca. The capacities were faded rapidly from the following cycles, probably due to the instability of the host material accompanying manganese dissolution. Detailed analyses with ICP-OES, EDX, XRD, and cyclic voltammetry (CV) with different scan rates indicated that both the intercalation and pseudo-capacitance are responsible for the reactions. As the research on calcium-ion batteries at an initial stage, this work demonstrates an example suggesting a possibility of discovering other new electrode materials for the calcium-ion batteries.

References

[1] A. Ponrouch, C. Frontera, F. Bardé, M. R. Palacin, Nature Materials
15, 169 (2016)
[2] R. Ma, Y. Bando, L. Zhang, T. Sasaki, Adv. Mater.
16, 918 (2004)
[3] S. Komaba, N. Kumagai, S. Chiba, Electrochimica Acta
46, 31 (2000)

Figure 1
The Development of Ester-Based Electrolyte Solutions for Magnesium Rechargeable Batteries
Authors: Sugita Miki , Doi Takayuki , Inaba Minoru 
Published: February 2020

Introduction

Magnesium (Mg) metal has attracted attention as an active material of a negative electrode for next-generation innovative rechargeable batteries because of its high volumetric capacity (3800 mAh cm-3) and low standard electrode potential (-2.73 V vs. NHE). High safety during charge/discharge cycles is also expected because Mg should be deposited uniformly without dendritic growth. Electrochemical deposition/dissolution reactions of Mg have been already reported using ether- and sulfolane-based electrolyte solutions such as Grignard reagents. However, the polarization of the Mg deposition/dissolution reactions was very high1). In addition, these electrolyte solutions are easily oxidized, and corrode aluminum current correctors. Therefore, the development of electrolyte solutions is necessary to realize magnesium rechargeable batteries with high working voltages above 3 V. In this study, we focused on ester-based electrolyte solution which is relatively stable against oxidation. We prepared electrolytes consisting of gamma-butyl lactone as a solvent and Mg(BF4)2 as a salt for magnesium rechargeable batteries. The electrochemical deposition/dissolution reactions of magnesium on Cu electrodes were investigated.

Experimental

The electrolyte solution used in this study was 0.1 mol dm-3 Mg(BF4)2 dissolved in gamma-butyl lactone, which was prepared in a glove box filled with Ar gas with a dew point below -80 oC. The water content was determined by Karl Fischer titration. The working, counter, and reference electrodes were Cu foil, Mg wire, and Ag/Ag+ electrode, respectively. Cyclic voltammetry was carried out between -1.00 and -4.00 V vs. Ag/Ag+ at a scan rate of 1 mVs-1 using three-electrode cells.

Results and discussion

0.1 mol dm-3 Mg(BF4)2/GBL used in this study contained 680 ppm water. Figure 1 shows cycle voltammograms of Cu in 0.1 mol dm-3 Mg(BF4)2/GBL at the first and fifth cycles. The cathodic current was observed at potentials below -3.3 V during the initial scan and a corresponding anodic current was seen at around -2.8 V. The reaction potentials were close to the standard potential of Mg (ca. -3.2 V vs. Ag/Ag+), and therefore the couple of redox currents should be assigned to deposition and dissolution reactions of magnesium on Cu. These results show that reversible deposition/dissolution reactions of magnesium can proceed in ester-based electrolyte solution. Mg(BF4)2 is considered as a promising salt for electrolyte solutions for magnesium rechargeable batteries. However, cycle performance needs to be improved; both the cathodic and anodic current densities decreased with cycle number, as shown in Fig.1. Charge/discharge characteristics and surface morphology of the electrode will be shown in our poster presentation.

Reference

1) D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature, 407, 724 (2000).

Figure 1
Sulfur-Infiltrated Hierarchical Porous Carbon (HPC) Cathodes for Lithium-Sulfur Batteries
Authors: Jung Dae Soo , Roh Kwang Chul , Choi Jang Wook 
Published: February 2020

Lithium sulfur (Li-S) batteries have been considered as promising candidates for next-generation battery applications because of its high theoretical capacity (1675 mAh/g is 5 times higher than those of traditional cathode materials based on transition metal oxides or phosphates), abundance, safety, low cost, and eco-friendliness. However, the practical implementation of Li-S batteries is greatly hindered by the high resistance of sulfur (5 x 10-30 S cm-1 at 25 oC) and dissolution of soluble long-chain lithium polysulfides (Li2Sn, 4≤n≤8) in the polar organic electrolytes, and volume expansion of sulfur during discharge process, resulting in an insufficient cycle life.
To this end, a number of studies have focused mainly on the development of carbon-sulfur composite with the intention to improve the cycle stability. Many types of mesoporous carbon materials have been studied as the electrically conducting host materials for improving the electrical conductivity of sulfur and preventing dissolution of soluble long-chain lithium polysulfides, which are intermediates formed as reaction in both discharge and charge processes in the electrolytes.
Those approaches improve the electrical conductivity of sulfur, but are associated with inherent limitation of the dissolution of polysulfides due to the limitation of physical adsorption of the polysulfides by mesopores, which tends to limit the electrochemical performance of carbon-sulfur composite cathode materials.
Recently, to overcome these problems, microporous carbon materials have been designed. Although the characterization of sulfur confined in micropores is not completely determined, the micropores have indeed turned out to be efficacious in mitigation of the soluble lithium polysulfides via various mechanisms: (1) strong adsorption of soluble polysulfides, (2) construction of solvent-free environment, and (3) formation of insoluble small S2-4 molecules. Because of these attributes, the microporous carbon-sulfur composites show outstanding cycling performance and rate capability. Additionally, Manthiram et al. reported a novel Li-S cell configuration having carbon interlayers with micropores between the separator and the regular sulfur electrodes. This interlayer works as polysulfide stockroom to maintain the cycle stability.
Based on these micropore approaches, we combined sulfur encapsulation and micropores into a single electrode component by developing a hierarchical porous carbon (HPC) structure. In the HPC structure prepared by spray pyrolysis process, the inner meso- and macro- pores are surrounded by outer carbon shell with micropores. Hence, stable cycling was achieved by the outer micropores that shut dissolution of lithium polysulfides down, while most of active sulfur was loaded in the larger inner pores.
Electrochemical Performance of NaNiCoMnO2 for Cathode Material in Sodium Ion Batteries
Authors: Shin Gyuho , Kim Sung-soo 
Published: February 2020

Lithium ion batteries have emerged as the best suited power source for portable electronics. They are also being considered as strong contenders to meet the energy demands of the transport sector. However lithium cannot be considered as an abundant element and its natural resources are unevenly distributed.
Sodium-ion batteries (NIB) appear as a promising alternative to the well-established lithium batteries technology. Sodium natural resources are unlimited everywhere as sodium is the fourth most abundant element on earth. Layered sodium transition metal oxides, NaxMO2 (M = transition metals), appear as very interesting cathode materials. The interest in these layered oxides probably arose from their high capacities and ease of synthesis
In this study, we synthesized NaNiCoMnO2 as the cathode material and its electrochemical performance was measured. Also the Na ion intercalation and deintercalation behavior was studied using Galvanostatic Intermittent Titration Technique(GITT) and Cyclic voltammetry (CV)
Insight into the Na-Storage Mechanism of Bismuth Oxyiodide Anode Materials
Authors: Liu Xiaoxiao , Huang Yunhui , Hu Xianluo 
Published: February 2020

Sodium ion batteries, as an important alternative to lithium ion batteries, and a new kind of energy powering device, have attracted intensive attention because of the high natural occurrences of sodium on the earth and also its similar chemical nature to lithium.[1] Sodium ion has larger radius than lithium ion, nevertheless, which would immediately affect Na+ ion insertion into active materials, resulting in a poor battery performance.[2] Therefore, it has become an urgent task to find novel materials with outstanding sodium storage properties.
The novel application of BiOI, as a new anode material for sodium ion batteries, is reported here for the first time. BiOI microspheres were directly synthesized by a simple solution method, which is promising for large-scale industrial production. The Na-storage mechanism was explored in details by ex-situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), which are powerful tools for investigating electrochemical reaction mechanisms. Our results showed that the layered BiOI underwent irreversible structure changes in charge-discharge processes. The final discharged product was detected to be a sodium bismuth alloy compound, while the charged product was not BiOI instead of the Bi metal. It acts as the active material taking part in the following electrochemical reactions, especifically the alloying-dealloying reactions. Furthermore, we also found a facile way through coating BiOI with rGO to improve the cycling performance of this novel anode material. The detailed understanding and the modifying methods might shed lights on investigating and applying other kinds of materials toward a broader range of both energy and other areas.
[1] C. Chen, Y. Wen, X. Hu, X. Ji, M. Yan, L. Mai, P. Hu, B. Shan, Y. Huang, Na(+) intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling, Nature Communications, 6 (2015) 6929.
[2] M.D. Slater, D. Kim, E. Lee, C.S. Johnson, Sodium-Ion Batteries, Advanced Functional Materials, 23 (2013) 947-958.

Figure 1
(Invited) Electrochemical Sensing Using Molecule-like Gold Nanoclusters
Authors: Kumar S. Senthil , Kwak Kyuju , Lee Dongil 
Published: February 2020

Gold nanoclusters with atomic precision, for example, Au25(SR)18, Au38(SR)24, Au67(SR)35 and Au144(SR)60, where SR is organothiol, have attracted much attention in recent years because of their importance in both fundamental science and technological applications. These molecule-like nanoclusters display unique properties, such as quantized single-electron charging and molecule-like redox activities, that differ substantially from those of the corresponding atoms and bulk materials. This presentation reports electrochemical and optical properties of these nanoclusters and their use in electrochemical sensing. Voltammetry of these nanoclusters exhibited well-resolved, reversible redox peaks and size-dependent electrochemical HOMO-LUMO gaps that could be correlated to optical and calculated energy gaps. These nanoclusters also showed excellent electrocatalytic activity toward oxidation of biologically relevant analytes. The modified electrode film prepared with Au25 nanoclusters exhibited excellent mediated electrocatalytic activity that was utilized for amperometric sensing of dopamine and glucose. The electron transfer dynamics in the Au25 film was examined as a function of Au25 concentration, which manifested the dual role of Au25 as an electronic conductor as well as a redox mediator. The electron transfer study has further revealed the correlation between the electronic conductivity of the Au25 film and the sensing sensitivity.
Applications of Electrochemical Impedance Spectroscopy in pH Sensor Characterization and Failure Analysis
Authors: Huo Jinshan 
Published: February 2020

pH sensors have been widely used in wet labs in research & development and production lines in various industries. Measuring the potential differences between pH and reference electrodes in pH buffers is usually used for calibration and performance test of a pH sensor. Electrochemical Impedance Spectroscopy (EIS), as a powerful analytical technique, has been used for the study of various electrochemical systems and processes. Nevertheless, the information about EIS study of pH sensors is rarely available from published resources.
This work presents: electrochemical impedance spectra of normal pH sensors and sensors with different defects, which result in different failure modes; how EIS can be used to facilitate the failure analysis of pH sensors; how EIS is used to study the aging mechanism of glass electrodes of steam-sterilizable pH sensors.
The work has shown that EIS can be used to facilitate the failure analysis of pH sensors by largely reducing destructive dissection work; hence save a lot of time for the process. EIS has also successfully been used to study the mechanism of glass electrode failure and the possibility to resume its performance after exposed to high temperature (Refer to Fig.1).

Figure 1
Step Response Analysis of MEMS Electro-Thermal Gas Sensors of Differing Geometry
Authors: Hesketh Peter , Mahdavifar Alireza , Shirke Amol , Stetter Joseph R , Struk Daniel 
Published: February 2020

MEMS gas sensors have the advantage of low power operation, fast response time, and have attracted a lot of interest because of their potential low cost. There is a need for monitoring of changes in the environment, in particular for carbon dioxide and methane. These gases can be detected using electro-thermal method based upon thermal conductivity changes. MEMS based micro-TCD which are ultra-low power, requiring less than 6 uJ per measurement and have a response time 100uS or less [1]. Because of their rapid response time they are also very suitable for MEMS-GC systems [2]. We have investigated different modes of pulsed operation for these sensors using constant current, constant resistance, constant power and constant energy. The detection of helium and hydrogen in nitrogen indicated a low level of detection less than 500ppm or better. A comparison of thermal time constants and resistance response for micro-thermal conductivity sensors with different aspect ratio, surface area to volume, operated at constant power density or at similar average temperatures will be discussed. Fitting a model based upon kinetic theory of gases to temperature dependent sensor response of gas mixtures has potential for evaluation of multi component mixtures.

References

[1]A. Mahdavifar, M. Findlay, J. R. Stetter, P. J. Hesketh, “Transient thermal response of micro-thermal conductivity detector for the identification of gas mixtures: An ultra-fast and low power method,” Nature Microsystems and Nanooengineering Vol. 1, pg. 15025 (2015).
[2] A. Mahdavifar , M. Navaei , P. J. Hesketh , J. D. Dimandja , J. R. Stetter , G. McMurray, “Implementation of a polysilicon micro electro-thermal detector in gas chromatography system with applications in portable environmental monitoring,” Journal of Solid State Science and Technology, Vol. 4, No. 10, pp. S1-S5 (2015).
3-D Printed Polymer MEMS
Authors: Takamatsu Kyuichiro , Yamada Naoya , Wada Masato , Ahmed Kumkum , Kawakami Masaru , Kassegne Sam , Furukawa Hidemitsu , Khosla Ajit 
Published: February 2020

This paper describes fabrication of complex 3-D printed Polymer MEMS Devices. Since geometric complexity is not a concern for 3-D printing, complex 3D microfluidics, MEMS and lab-on-a-chip devices can be easily fabricated that are otherwise time consuming and difficult to manufacture with state of the art 2-D MEMS fabrication technology. Furthermore, 3-D printed MEMS technology elimates the need for expenisve infrastruce required to manufacture MEMS devices such as clean room, photolithography equipment, masks etc.
Detection of Telomerase Activity Based on the Steric Hindrance Change in the Pore of Anodic Alumina Nanochannels
Authors: Liu Xu , Liu Yuan Jian , Wei Wei 
Published: February 2020

It has been confirmed that telomerase are closely related to cancers. [1] Urine telomerase measurement is nondestructive compared to blood analysis and pathology tests, which is significant for cancer discovery, development and prognosis. [2]

In this paper, a new method for detection of urine telomerase activity based on increment of steric hindrance in the porous anodic alumina (PAA) nanochannels was proposed. Telomerase primer (TS primer) was assembled firstly on the inner wall of PAA nanochannels. Then, under the action of active telomerase, TS primer was extend with repeat G-rich sequences (TTAGGG)n, which experienced configurational change to G-quadruplex in the presence of K+. As a result, the steric hindrance in the nanochannels changed accordingly. Telomerase activity measurement were proposed based on these steric hindrance changes. The increased anodic current, produced by ferricyanide, has a linear correlation with the HeLa cell number in the range of 10 - 5000 cells, with the detection limit of 7 cells. Compared with previously reported detection method based on the steric hindrance change in the PAA pore, the anodic change in this method is bigger because multiplex G-quadruplex formed with the action of telomerase, which was advantage to improve the detection sensitivity.[3] The method was simple and reliable, which was significant to the clinical cancer diagnosis.

References
：

[1] Moyzis, R. K.; Buckingham, J. M.; Cram, L. S.; Dani, M.; Deaven, L. L.; Jones, M. D.; Meyne, J.; Ratliff, R. L.; Wu, J. R. P. Natl. Acad. Sci. USA.,
1988, 85, 6622-6626.
[2] Wu, L.; Qu, X. G. Chem. Soc. Rev.,
2015, 44, 2963-2997.
[3] Yu, J. C.; Zhang, L. Q.; Xu, X.; Liu, S. Q. Anal. Chem., 2014, 86, 10741-10748.