bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Progress in High-Capacity Concentration Gradient Cathode for Next-Generation Electric Vehicles
Authors: Sun Yang-Kook
Published: February 2020

The ability of Li-ion batteries (LIBs) to provide portable high-density energy sources with outstanding cycle life has led to their deployment in recent electric vehicles (EVs). For wider consumer acceptance of EVs, however, the current state-of-the-art LIBs face formidable technological challenges, including concerns related to the battery cost, durability, and driving range. Resolving these hurdles requires substantial improvements in energy density, cycle life, and safety of current LIBs. Compared to the most widely accepted anode, graphite, cathodes suffer from inferior capacity, poor cycle life, thermal characteristics, and high cost. As a result, high-energy cathodes enabling a long cycle life and reliable safety need to be developed. Among them, a compositionally graded cathode material in which concentrations of the transition metals continuously varied from the particle center to the surface appears to be the most promising since the graded cathodes have demonstrated remarkable improvements over cathodes with single uniform composition, not only in lifetime and safety, but also in battery power due to the superior Li+ diffusion kinetics. In this presentation, we review the most recent and promising results concerning Li[Ni1-x-yCoxAly]O2 (NCA) and Li[Ni1-x-yCoxMny]O2 (NCM) cathodes. One example, concentration gradient Li[Ni0.9Co0.05Mn0.05]O2 cathode delivers a discharge capacity of 229 mAh g-1 and exhibits capacity retention of 88% after 1000 cycles in a pouch-type full cell (compared to 68% for the conventional NCM cathode). The proposed concentration gradient cathodes provide an opportunity for the rational design and development of a wide range of multifunctional cathodes, especially for Ni-rich NCM cathodes, by compositionally partitioning the cathode particles and thus optimizing the microstructural response to the internal strain produced in the deeply charged state.
(Invited) Functional Binders for Li-, Na-, and K-Ion Batteries
Authors: Komaba Shinichi , Horiba Tatsuo , Kubota Kei , Fukunishi Mika
Published: February 2020

A conventional binder for powdery composite electrodes, poly(vinylidene fluoride) (PVdF), is widely used in commercial lithium-ion electrodes because of its chemical and electrochemical stability and good affinity to the electrode and electrolyte materials. However, coverage of active material surface and adhesive strength of a composite layer onto a current collector are not enough to cope with severe conditions of electrode operation such as high potential or large volume change during a charge-discharge cycle. In addition, N-methyl-2-pyrrolidone (NMP) as solvent to dissolve PVdF binder to prepare electrode slurry is combustible and harmful. Since there has been intensive preference for alternative water-soluble polymer to PVdF binder, we study water-soluble polymers as new binders for lithium-ion cells, being convinced that binder is critical materials to maximize the intrinsic performance of active materials and to modify the negative electrode surface including SEI to suppress undesired side-reactions at graphite electrode [1]. Recently, we extend our work on binder towards cross-linked and natural polymers for negative and positive electrodes for Li, Na, and K batteries. We will present detailed results to realize high-energy electrode performance with new binders such as polyacrylates [2-4], covalently crosslinked polyacrylates [5], branched polysaccharides [6], polyglutamates [7,8], and SBR latex [9]. We will also discuss the mechanism of better performance compared to that for conventional PVdF with characterization data and surface analyses.

References:

[1] S. Komaba et al., ECS Trans, 11 (29) 63-70 (2008).

[2] S. Komaba et al., J. Power Sources, 189, 197 (2009).

[3] Z.-J. Han, S. Komaba, et al., Phys. Chem. Chem. Phys., 17, 3783 (2015)

[4] M. Fukuknishi, K. Kubota, T. Horiba, S. Komaba et al., Electrochem., 87, 70 (2019).

[5] S. Aoki, S. Komaba, et al., J. Electrohem. Soc., 162, A2245 (2015).

[6] M. Murase, S. Komaba, et al., ChemSusChem, 5, 2307 (2012).

[7] T. Mochizuki, T. Horiba, S. Komaba, et al., ACS Sustainable Chem. Eng., 5, 6343 (2017).

[8] Y. Yoda, K. Kubota, T. Horiba, S. Komaba, et al., ACS Appl. Mater. Interfaces, 10, 10986 (2018).

[9] N. Yabuuchi, S. Komaba et al., J. Electrochem. Soc., 162, A538 (2015).
Design Criteria of SEI Layers for Lithium-Ion Batteries with Aqueous Electrolytes
Authors: Oh Dahyun , Subramanya Usha , Chua Charleston , Pusri Sanyam
Published: February 2020

Using aqueous electrolytes in lithium-ion batteries (LIB) has been difficult due to the narrow electrochemical stability window (1.23 V) of water. Super-concentrated aqueous electrolytes provide a way to overcome this challenge, expanding the stable voltage window to 4 V. Thus, the high concentration of salts in aqueous electrolytes, also called ‘water-in-salt’ systems, opened an avenue to replace flammable organic electrolytes without compromising the energy density of LIB. However, the cathodic stability limit of this super-concentrated aqueous electrolyte (1.9 V versus Li) is still too high to provide a sufficiently large difference of electrochemical potential between cathode and anode pairs to achieve a high theoretical energy density. Here we report synthesis methods to introduce artificial solid-electrolyte interphase (SEI) layer that prevents access of water molecules on anodes while passing lithium-ions to sustain battery reactions in an aqueous environment. We investigated the ideal composition of artificial SEI layer to enhance the transport of lithium-ions in super-concentrated aqueous electrolytes by evaluating the cycle life of batteries.
Lithium-Ion Transport and Cycling Characteristics of Fluorinated Electrolytes
Authors: Shah Deep B. , Nguyen Hien Q. , Grundy Lorena S. , Olson Kevin R. , Mecham Sue J. , DeSimone Joseph M. , Balsara Nitash P.
Published: February 2020

Electrical energy is ubiquitous in the modern world, and in order to continue pushing boundaries on consumer wearables, electric vehicles, and grid storage, secondary lithium-based rechargeable batteries need to be enhanced. The performance of binary electrolytes is governed by the electrolyte thermodynamic factor and three transport properties: conductivity, salt diffusion coefficient, and transference number. Rigorous methods for measuring conductivity and the salt diffusion coefficient are well established in literature. NMR and the steady-state current method are often used to measure the transference number, but are predicated on the dilute solution assumption and do not fully consider the non-ideality of the electrolyte. Within this work, we elucidate a complete set of lithium-ion transport properties for mixtures of dimethyl carbonate terminated perfluorinated tetraethylene ether and lithium bis(fluorosulfonyl)imide (LiFSI). The steady-state current transference number is positive across all concentrations and decreases with salt concentration, while the NMR transference number is approximately 0.5 everywhere. In contrast, we find that the transference number using Newman’s concentrated solution theory is negative across all concentrations. We show that Newman’s concentrated solution theory allows for accurate potential and limiting current modeling of lithium half cells whereas the steady-state current transference number severely over-estimates the electrolyte’s limiting current. The disparity between the dilute solution theory measurements and that of Newman’s concentrated solution theory approach indicates the dominance of ion clustering.

Figure 1
Effects of Esters Used in Liquid Electrolyte for Li(Ni0.6Mn0.2Co0.2)O2/Graphite Pouch Cells Under Fast Charging
Authors: Wu Xianyang , Liu Tianyi , Zhao Kejie , Lin Feng , Wood David L. , Belharouak Ilias , Du Zhijia
Published: February 2020

Electrolyte plays a critical role in lithium ion batteries (LIBs) as it determines the ion conductivity and dictates the formation of solid electrolyte interphase (SEI)1. Typically it consists of cyclic carbonate and linear carbonate, and it is believed via combination of cyclic carbonate possessing high polarity and dielectric constant but high viscosity while linear carbonate with low polarity, low dielectric constant and lower viscosity, the mixed solvent will provide satisfactory performance.

Nowadays urgent needs for high performance LIBs from electrical vehicles (EVs) industry propel the development of LIBs capable of fast charging, and addition of esters possessing lower viscosity2,3 into the commonly used liquid electrolyte as cosolvents is considered as a possible solution to this problem. Herein performance of esters including Ethyl Acetate (EA), Methyl Acetate (MeOAC) and Ethyl Formate (EF) are investigated via cycling tests.

Firstly, physical properties (viscosity, ion conductivity and transfer numbers) of the blended electrolyte systems, consisting of 1.2 mol/L LiPF6 solvated in EC/EMC/Esters (30:50:20 wt%) are studied. Experimental results clearly show the improvement of ionic conductivity with adding the four esters compared to baseline electrolyte (1.2 mol/L LiPF6 in EC/EMC. For viscosity, the electrolytes with ester co-solvents all have lower viscosity than the baseline electrolyte over all the salt concentrations. Cycling tests are also performed for 520mAh Li(Ni0.6Mn0.2Co0.2)O2/graphite pouch cells between 2.8V-4.2V at 30°C. The cells were charged at 4C (charging ends at 15 minute) and discharged at 1C, and the result is shown in Figure 1. The cell performance and analysis will be presented during the meeting.

References:

[1] Xu, Kang. "Electrolytes and interphases in Li-ion batteries and beyond." Chemical reviews 114.23 (2014): 11503-11618.

[2] Ma, Xiaowei, et al. "A study of highly conductive ester co-solvents in Li [Ni0.5Mn0.3Co0.2] O2/Graphite pouch cells." Electrochimica Acta 270 (2018): 215-223.

[3] Smart, M. C., B. V. Ratnakumar, and S. Surampudi. "Use of organic esters as cosolvents in electrolytes for lithium-ion batteries with improved low temperature performance." Journal of The Electrochemical Society 149.4 (2002): A361-A370.

Figure 1. Cycling performance for the 4 blended electrolyte using EF, MeOAC, EtOAC and DMC

Figure 1
Tracking Battery Swelling in Uncompressed Li-Ion Cells Via in-Operando X-Ray Radiography and Micro-Tomography
Authors: Fahy Kieran F. , Shafaque Hisan Waleed , Shrestha Pranay , Ouellette David , Ge Nan , Ikeda Nobuhisa , Kotaka Toshikazu , Tabuchi Yuichiro , Bazylak Aimy
Published: February 2020

Li-ion battery swelling during cycling is known to be a major cause of battery electrode degradation and can contribute significantly to cell failure [1,2]. The main cause of battery swelling is due to the intercalation of Li into the carbon and LiCoO2 electrodes. This swelling is known to occur anisotropically due to the electric field and Li salt distributions in the electrode [3].

We have used x-ray radiography and µCT to map this swelling, in-operando under charge and discharge conditions, in the layers of an uncompressed Li-ion battery. This study gives insight into the relationship between the battery state of charge and the electrode swelling. The change in swelling due to the electrode geometry is also investigated.

Li-ion pouch cells were cycled at 0.5, 1 and 2 C while undergoing x-ray radiography and tomography at the BMIT beamline of the Canadian Light Source. Synchrotron radiography allowed the tracking of the electrode swelling in two dimensions with high temporal (10 s/frame) and spatial resolution (3 µm/pixel). µCT measurements of Li-ion cells were carried out under the same battery cycling conditions and scans were taken at 0, 25, 75 and 100 % state of charge (3 µm/pixel, 225 s/scan). Reconstruction and segmentation of the collected images allowed for the measurement of each electrode volume.

From these results it appears that electrode swelling depends on a number of factors, including electrode geometry, charge/discharge rate and battery age. There is also a noticeable degree of irreversibility in the swelling of the electrode, which may be a possible metric for battery degradation. The quantification of the carbon electrode swelling corresponds closely with the theoretical value for lithium intercalation to LiC6, although there is a discrepancy between the swelling value obtained for the LiCoO2 electrode and theory.

These results give a valuable insight into the mechanical dynamics of Li-ion batteries under in-operando conditions and will provide validation to, and data for, battery models including stress-strain and degradation models.

References

Bond, T., Zhou, J., & Cutler, J. (2017). Electrode Stack Geometry Changes during Gas Evolution in Pouch-Cell-Type Lithium Ion Batteries. Journal of The Electrochemical Society, 164(1), A6158–A6162.

Chen, C., Wei, Y., Zhao, Z., Zou, Y., & Luo, D. (2019). Investigation of the swelling failure of lithium-ion battery packs at low temperatures using 2D/3D X-ray computed tomography. Electrochimica Acta, 305, 65–71.

Zhang, N., & Tang, H. (2012). Dissecting anode swelling in commercial lithium-ion batteries. Journal of Power Sources, 218, 52–55.

Figure 1 (a) 2D x-ray radiography of a Li-ion pouch cell and (b) 3D reconstruction of a µCT of a Li-ion pouch cell section.

Figure 1
Probing the Chemical and Structural Stability of Oxide Cathodes Using a Surface Model Reaction
Authors: Waters Crystal K , Lin Feng
Published: February 2020

As the demand for batteries grows, there is a need for scientists to catapult efforts into further understanding surface structure and electronic properties in Li-based, layered transition metal oxide (TMO) materials. This research hypothesizes potential surface oxygen and electron transfer pathways by using benzyl alcohol oxidation as a model surface reaction.

There are many opposing theories that arise about the mechanism by which oxygen and electrons are transferred between the cathode and electrolyte. To fill the knowledge gap, a common Li-based TMO was explored using extensive X-ray spectroscopy and electron microscopy analysis to investigate the structure – activity relationship. The work proposed assists in (1) designing a model to study oxygen pathways by using a surface probe reaction, (2) determining surface electronic changes after probing, and (3) hypothesizing a mechanism for the oxygen transfer at the oxide cathode surface. This study provides a chemical basis for improved battery materials design. Conclusions from this work will assist in rationalizing the cathode-organic molecule interactions. In efforts to promote green chemistry methods, this work also hypothesizes avenues to repurpose recycled battery materials in catalytic regimes.
Electrochemical Performance of AlF3-Coated LiNi0.5Mn1.5O4 5-V Cathodes at Elevated Temperature
Authors: Lin Jeng-Yu , Chu Ching-Teng
Published: February 2020

In the past decade, rechargeable lithium-ion batteries (LIBs) are acknowledged as one of the most suitable energy storage devices due to their high energy density, excellent cyclic performance, high power density, environmentally friendly and high operation voltage conditions. However, the development of LIBs with high energy density, high rate capability and reasonable lifetime is of great importance to meet their growing applications from portable gadgets to electric vehicles (EVs), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicle (PHEV). Up to date, LiNi0.5Mn1.5O4 (LNMO) has been regarded as one of promising cathode materials due to its high and flat working potential at around 4.7 V Vs Li/Li. The high working potential of LNMO corresponds to the high energy density and it exhibits the 658 Wh Kg-1 which is significantly higher than that of the that of LiMn2O4 (440 Wh kg-1) or LiFePO4 (591 Wh kg-1). However, the main issue of high-voltage spinel LNMO is its limited cycle life, especially at a high temperature, which is triggered by decomposition of electrolyte or dissolution of Mn/Ni at high operating potential.

In the present investigation, the surface modification of LNMO cathode materials was conducted by coating with thin layer to suppress the electrolyte decomposition and transition metal dissolution at high voltage. The surface morphology and crystal structure of the AlF3-coated LNMO were systemically investigated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM) equipped with an energy-dispersive X-ray spectroscope (EDS). According to the series of electrochemical studies, it is found that the introduction of AlF3 conductive coating layer significantly enhanced the rate and cycle life of the LNMO spinel cathode than the pristine LNMO cathode, especially at elevated temperature. The optimum loading of AlF3 layer on LNMO surface was found to be 1 wt.%. The 1 wt.% AlF3-coated LNMO can maintain a stable discharge capacity of 100 mAh g-1 even after consecutive charging/discharging for 50 cycles at 0.1 C at 55oC.
Direct Observation of Electrochemically Active Fe3+/Fe4+ in LiCo0.8Fe0.2MnO4 By in Situ Mössbauer and in Situ X-Ray Absorption Spectroscopy
Authors: Indris Sylvio , Dräger Christoph , Ehrenberg Helmut
Published: February 2020

The usage of Fe at high oxidation states might be interesting for increasing the energy density of Li-ion batteries and also for substituting expensive/toxic elements in the cathode materials. The redox activity of Fe3+/Fe4+ in the spinel LiCo0.8Fe0.2MnO4 has been investigated via in situ Mössbauer spectroscopy and in situ X-ray absorption spectroscopy (XAS) during electrochemical cycling in a complete Li battery cell [1]. The initial Mössbauer spectrum consists of a doublet with isomer shift IS = 0.330(1) mm/s and quadrupole splitting QS = 0.722(1) mm/s (Fig. 1). These parameters are characteristic of Fe3+ in a high-spin state on the octahedral sites of the spinel structure. In the beginning of the charging process vs. Li+|Li, a broadening of this doublet can be observed. This corresponds to an increased electric field gradient at the site of the Fe nuclei, i.e. an increase of structural disorder around the Fe ions, and is probably cause by the initial oxidation of Co.

During further charging, the Fe3+ doublet successively disappears and is replaced by a new narrow doublet with isomer shift of -0.134(6) mm/s. This negative value clearly reveals that Fe4+ is formed. Further cycling between 5.3 V and 4.3 V reveals that this oxidation is highly reversible.

The XAS spectra acquired during charging of LiCo0.8Fe0.2MnO4 vs. Li+|Li clearly show a shift of the Fe K absorption edge towards higher binding energies and thus an oxidation of Fe3+ to Fe4+. The XAS spectra acquired during discharging show again that this process is fully reversible.

In summary, the reversible formation Fe4+ was clearly observed by both methods, hence proving the electrochemical activity of Fe at voltages above 5 V vs. Li+/Li. This enables future research on new environmentally benign and inexpensive electrode materials with operating voltages above 5 V and thus an increased energy density.

[1] Observation of Electrochemically Active Fe3+/Fe4+ in LiCo0.8Fe0.2MnO4 by in situ Mössbauer Spectroscopy and X-Ray Absorption Spectroscopy,

C. Dräger, F. Sigel, R. Witte, R. Kruk, L. Pfaffmann, V. Mereacre, M. Knapp, H. Ehrenberg, S. Indris, Phys. Chem. Chem. Phys.
21, 89-95 (2019).
A New Method to Study Depth Profiles in Silicon/Carbon Composite Electrodes
Authors: Richter Karsten , Waldmann Thomas , Kasper Michael , Pfeifer Claudia , Memm Michaela , Axmann Peter , Wohlfahrt-Mehrens Margret
Published: February 2020

Si as active material has become a prominent candidate as anode material for high-energy Li-ion cells. Unfortunately, Si in Si/C anodes is hard to quantify by established methods, e.g. with ICP-OES no depth profile can be obtained and HF is needed for digestion.

Here, we present a semi-quantitative depth profiling method based on glow discharge optical emission spectroscopy (GD-OES). The GD-OES calibration covers Si contents in the range of 0-100 wt.-% in the anode. The results are validated with lab and pilot line coated anodes with known Si contents. The quantified depth profiles with different pristine anodes show a homogeneous distribution of Si and therefore the presented GD-OES method is capable of assessing the quality of composite active materials, from graphite dominant up to pure Si1.

The GD-OES method is further applied to anodes obtained from Post-Mortem analysis of commercially available 18650 and 21700 cells. The measurements reveal that the anodes of state-of-the-art Li-ion cells contain up to 5% wt.-% Si.

GD-OES depth profiles of anodes after formation (anodes coated in our labs as well as anodes from commercial cells) show a Si peak near the anode surface (near the anode | separator interface, see Figure 1a. This peak changes with aging and is decreased when the anodes are washed with DMC (see Figure 1b). The presence of this peak is further investigated by EDX of ion milling cross-sections. ICP-OES of the DMC washing solution indicates soluble Si species. This aging mechanism is further investigated by Raman spectroscopy.

Acknowledgement:

The research leading to these results has been performed within the project LIB.DE and received funding from the federal ministry for economics and energy Germany (BMWi) under contract n° 03ET6081A.

Literature:

K. Richter, T. Waldmann, M. Memm, M. Kasper, and M. Wohlfahrt-Mehrens, J. Electrochem. Soc., 165, A3602–A3604 (2018).

Figure 1
Modeling Impact Safety of Lithium-Ion Batteries in Electrified Vehicles
Authors: Deng Jie , Bae Chulheung , Miller Ted J. , L'Eplattenier Pierre
Published: February 2020

Lithium-ion batteries have been widely used for an energy storage system in electrified vehicles due to their high energy and power densities. Improving the safety of lithium-ion battery system is one of the top priorities in the electrified vehicle design since it is directly related to the safety of passengers. Various abuse tolerance tests have been developed to evaluate the failure conditions of lithium-ion battery cells, modules and systems. Nevertheless, these tests can be expensive and time consuming, and in some cases provide limited information on the failure mechanisms of batteries. As such, computational modeling has gained a lot of interests and played a more and more important role in evaluating the battery safety under different abuse scenarios. Here we present a multi-physics battery safety model that is able to predict coupled mechanical, thermal, electrical and electrochemical responses of automobile lithium-ion batteries under abusive conditions. In this model, the electrochemical behavior of batteries is described by a spatially distributed equivalent circuit model, where polarization and damping effects are captured by a resistance-capacitance network. During simulations, the mechanical solver predicts the onset of short circuit, and then the coupled thermal, electrical and electrochemical solver captures the evolution of temperature, voltage and current distribution after short circuit initiation. In order to make the proposed model applicable to module or pack level simulations, various element formulations and strategies have been developed to improve computational efficiency without scarifying much accuracy. Details of model set up, parameters evaluation, and case studies that demonstrate the model capabilities will be presented. Experimental validation of model prediction as well as the future development of this framework will also be discussed.
High-Throughput Studies of Li-Battery Materials
Authors: McCalla Eric
Published: February 2020

In the search for better performing battery materials, high-throughput approaches have the potential to screen large composition spaces in a short period of time and thereby greatly accelerate the development of advanced materials. The challenges are numerous both in terms of synthesis which is often done at much smaller scale than in commercial settings (e.g. milligrams) and in terms of characterization. Often times, the characterization cannot be performed in high-throughput thereby slowing down the process to be comparable with traditional routes. The McCalla group has been working on both of these aspects. The group now uses high-throughput synthesis techniques to make layered oxide cathodes (Li- and Na-ion), high-power anodes (Li-ion) and solid electrolytes. Characterization techniques now performed in high-throughput in the group include X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy (for both ionic and electronic conductivities in solid electrolytes as well as impedance growth during cycling in Li-ion cells). This allows the synthesis and characterization of approximately 400 different samples per week by a small and growing research group. Herein, I will provide an overview of these techniques and show how they are now being applied to a broad array of systems of interest for Li batteries (Li-ion and all-solid).
Probing the Effect of the Depth of Discharge Range and C-Rate on the Lifetime of Li-Ion Cells at Different Temperature
Authors: Gauthier Roby , Louli Alexander J. , Dahn Jeff R.
Published: February 2020

Li-ion batteries are commonly used in electric vehicles. However, the finite lifetime of these batteries is a common problem and its resolution is a significant challenge for electric vehicle companies. Frequently, the lifetime of Li-ion cells is studied using full-charge/full-discharge cycling protocols. Since many users of electric vehicles travel mostly locally, full discharges should occur infrequently if the users are charging nightly. Consequently, many laboratory experiments don't describe reality very well. The present research looked at the cycling performance of NMC622/graphite 2% VC, 1% MMDS and 1% TTSPi (VC211) cells for eight different depth of discharge ranges and three different C-rates at 20°C and 40°C. Testing has been in progress for more than 2 years for most cells. The capacity fade trend versus the change in depth of discharge (ΔDOD) and C-rate was studied. Additionally, operando pressure measurements versus voltage were acquired, to quantify the non-linear expansion of the graphite electrode versus cell state of charge, and compared to the capacity fade trend versus ΔDOD. According to past research1, the effects of different DOD ranges on capacity fade can be explained by the cracking of the SEI assuming linear graphite expansion with state of charge, however there was little data available to compare to the model predictions. The mathematical model developed by Deshpande et al.1 has been compared to our extensive experimental data and conclusions were made.

R. D. Deshpande and D. M. Bernardi, J. Electrochem. Soc., 164, A461–A474 (2017).

Figure 1
Gold Nanoparticle Embedded Modified MWCNT Electrodes for Electrochemical Detection of Arsenic in Water
Authors: Mitra Shirsendu , Roy Nirmal , Bandyopadhyay Dipankar
Published: February 2020

Email of corresponding author: dipban@iitg.ac.in

Abstract: We focus on electrochemical detection of arsenite and/or arsenate in water using different kinds of electrodes made from gold nanoparticle embedded on substituted multiwall-carbon-nanotubes (MWCNT). The CNTs were functionalised with thiol groups by reaction with cysteamine. Following this, three different electrodes were fabricated using thiol substituted MWCNTs, gold nanoparticle (Au NP) embedded thiol substituted MWCNTs, and magnetite doped Au NP embedded MWCNTs. Subsequently, effect of Au NPs on the electrodes in the selectivity and sensitivity of the sensor was studied. The aforementioned experiments suggest that the affinity of the arsenite ions towards the thiol groups were found to be magnified by the integration of an optimal amount of Au NPs. Further, addition of magnetite particles in the CNT matrix made the sensor more sensitive towards arsenic detection. The working principles, mainly the change of the surface potential, of the electrodes were characterized by surface potential microscopy (SPOM) study using atomic force microscopy (AFM). The study helped in the miniaturization of the arsenic sensor using screen printed commercial electrode system with a modification of the working electrode based on requirement as stated before. Interestingly, we extracted the electrochemical response using an open source Arduino UNO based potentiostat unit, as shown in Fig. 1, to translate the concept into a portable electrochemical arsenic sensor.

Keywords: Arsenite/Arsenate sensor, electrochemical, Screen printed electrode, Gold nanoparticle, Arduino UNO.

Figure 1
Physics of Neutron-Gamma Sensors for Soil Elemental Analysis
Authors: Kavetskiy Aleksandr , Yakubova Galina , Sargsyan Nikolay , Prior Stephen A. , Torbert H. Allen , Chin Bryan A.
Published: February 2020

Soil elemental (mainly carbon) analysis is one of the critical features in agricultural practice. The based on different physical principal methods are began applied today instead of traditional chemical analysis. One of such methods is neutron-gamma analysis. This method has a lot of advantage before traditional methods. It is nondestructive in situ method, no sample preparation is needed, no time consuming and labor-intensive method. Method is based on the registration of gamma rays response of the main soil nuclei at its irradiation by fast neutron flux.

In this report we will discussed physical principles of this method, namely processes of penetration, moderation and interaction with soil elements of fast neutrons, gamma rays appearing and propagation in soil, creating the gamma spectra in gamma detector. Based on this discussion the ways of soil elemental content determination from gamma spectra will be represented. The comparison of received results of neutron-gamma analysis with data of chemical analysis demonstrate that this method can replace this last in agricultural practice.
Development of Full Color 3D Gel Printer Using Color Gel System
Authors: Takahashi Mizuki , Saito Azusa , Kawakami Masaru , Furukawa Hidemitsu
Published: February 2020

The 3D Gel Printer Soft and Wet Industrial Materials・Easy Realizer (SWIM-ER) developed by Furukawa et al. It can only perform modeling with monochrome. Therefore, it is thought that new elements will be born by developing a new 3D Gel Printer. However, there are many problems in developing it. In this study, we aim to develop a system that displays the composition of gels for obtaining color gels of target color, and apply it to gel printer. The color gels used pigments, and mixing them showed the change of color of the gels. Moreover, by mixing the pigments, gels with a wide range of color variations could be obtained.In the future, we will study the improvement of accuracy by collecting more samples and the technology to actually color the gels.
One-Step Covalent Immobilization of β-Cyclodextrin on sp2 Carbon Surfaces for Ultrasensitive and Selective Guest Detection
Authors: Li Zhi , Van Guyse Joachim F. R. , Retamero de la Rosa Victor , Van Gorp Hans , Walke Peter , Uji-i Hiroshi , Hoogenboom Richard , De Feyter Steven , Mertens Stijn F. L.
Published: February 2020

The modification of solid surfaces with supramolecular hosts is a powerful method to tailor interfacial properties and confer chemical selectivity, but often involves multistep protocols that hinder facile upscaling. Here, we demonstrate the one-step covalent modification of highly oriented pyrolytic graphite (HOPG) with a β-cyclodextrin (β-CD) derivative, which efficiently forms inclusion complexes with hydrophobic guests of suitable size (e.g. ferrocene, dopamine). The modified β-CD-HOPG electrode discriminates analytes that form host-guest complexes with β-CD against a 100-fold higher background of electroactive substances that do not, even when these possess similar redox potentials. In addition, the enrichment of the analytes at the electrode surface, through complex formation with the β-CD units, leads to an enhanced electrochemical response and an improved detection limit (one order of magnitude for dopamine, compared to current cyclodextrin-based sensors).

The two unique features we demonstrate for the covalently grafted β-CD-HOPG electrode (selective sensing of hydrophobic analytes and ultrasensitive dopamine detection) do not come at the expense of ease of preparation: the one-step covalent modification can be completed in minutes, using standard electrochemical cells and equipment. Also, the procedure uses robust, commercially available HOPG substrates that can be reused by mechanical exfoliation many times, lowering the operational cost and further increasing wide accessibility and attractiveness of our approach.

The fundamental reasons for the high performance of the sensor may be related to its simple and well-defined structure, in which all the sensing units (covalently attached β-CD-moieties) are positioned uniformly and close to the collector surface (HOPG). This is achieved by the chemical characteristics of both reagent (a highly reactive, but sterically hindered diazonium compound, yielding monolayer modification exclusively) and substrate (low-reactive sp2 carbon surface, requiring highly reactive radical reagents for its modification), resulting in negligible side reactions despite the simplicity of the approach. These principles, and the resulting performance, can be taken as a proof of concept for entirely different sensors, e.g. using other van der Waals solids as substrates, but based on analogous chemistries.
Selective Isolation and Concentration of Foodborne Bacterial Pathogens in a Microfluidic Device
Authors: Ghuman Alyssa , Zhou Yan , Ramasamy Ramaraja P.
Published: February 2020

Listeria monocytogenes is a bacterium that is present in contaminated food products including dairy, vegetables and meat. It is a deadly foodborne pathogen that has contributed to multiple outbreaks, and the disease caused by this pathogen has high mortality rates. The conventional methods used for Listeria detection include standard microbiology or biochemical procedures, which require time-consuming sample pretreatment techniques that can take up to 72 hours. There is a growing need for methodologies that reduce the test time for Listeria detection from days to an hour or less, while also allowing for scalability and high-volume processing. The challenge lies in processing and pretreating large volumes of food samples to generate sufficient quantities of analyte for detection tests within a short time period, without compromising the selectivity of the test. We have previously worked on the development of separation and detection methods for bacterial cells [1, 2]. This work describes a multi-chamber microfluidic cell sorting device that uses magnetophoresis to detect, separate, and concentrate tagged Listeria monocytogenes from food samples. Bacteriophage-functionalized magnetic particles will be used to isolate the bacteria in a food sample for pre-concentration, which will allow for more rapid and selective cell sorting followed by impedimetric detection of Listeria in an electrochemical cell.

Ghuman, A., et al., Magnetic Separation of Food-Borne Pathogens in a Microfluidic Device, in IBE 2018 Annual Conference. 2018.

Zhou, Y., et al., Isolation and Separation of Listeria monocytogenes Using Bacteriophage P100-Modified Magnetic Particles. Colloids and Surfaces B: Biointerfaces, 2018. Under Review.
Ethanol Gas Sensors Based on ZnO Nanotube Structures Fabricated By Atomic Layer Deposition
Authors: Lin Pengtao , Zhang Kai , Baumgart Helmut
Published: February 2020

Among various Metal Oxide Semiconductor (MOS) gas sensors, ZnO nanostructure gas sensors have been widely used due to its large exciton binding energy, wide band gape of 3.37 eV, large exciton binding energy of 60 meV at room temperature, good electrical conductivity, low cost, and high mechanical stability. Furthermore, a variety of morphology has been developed to improve the properties and applications. In this work, ZnO nanotube nanostructures were fabricated as gas sensors to sense ethanol vapor due to its high electrochemical stability, nontoxicity, and, especially, high surface-to-volume ratio. Several coaxial ZnO nanotubes were synthesized on porous substrate to further enhance the sensing response to ethanol vapor with increased reaction surfaces in ZnO nanostructures.

In this study, ZnO nanotubes were synthesized by Atomic Layer Deposition (ALD) on Anodic Aluminum Oxide (AAO) templates with sacrificial Al2O3 layers. The second Al2O3 sacrificial layer followed by ZnO layer was synthesized on AAO samples by ALD with TMA (Al2(CH3)6) and DI water as precursors. In addition, the third ZnO thin film layer were deposited on the surface of the sacrificial layer of Al2O3 with precisely controlled thickness by ALD. The entire procedure outlined above for fabricating ZnO-Al2O3-ZnO structures is considered as one super cycle. More super cycles were applied to synthesize additional coaxial ZnO nanotubes. To eliminate the sacrificial layer, a Precision Ion Polishing System (PIPS) was used to remove the top cover as shown in Figure 1. Therefore, the Al2O3 sacrificial layers were exposed for Sodium Hydroxide (NaOH) wet etching. After the sacrificial layers were removed by NaOH, ZnO nanotube gas sensors were formed as shown in Figure 1 (b).

To investigate the sensing performance of ZnO nanotube gas sensors to ethanol vapors, a gas sensor testing system was developed with a sealed reaction chamber and a control system with stable temperature control and accurate gas concentration control. The sensing performance of the MOS gas sensors consisting of only core single crystal ZnO nanotubes, was compared to sensors consisting of double nested coaxial ZnO nanotubes, and further compared to three nested tube-in-tube coaxial ZnO nanotube structures and analyzed under various ethanol vapor concentrations at different temperatures. The ZnO nanostructures sensing results on ethanol vapor demonstrated the sensing performance was considerably enhanced due to the increased surface to volume ratio in the ZnO tube structures.

Figure 1
RF Sputtered Boron Carbon Nitride (BCN) Thin Films for Biological Applications
Authors: Nehate Shraddha Dhanraj , Saikumar Ashwin Kumar , Naga Varsha , Sundaram Kalpathy B.
Published: February 2020

Boron carbon nitride (BCN) films have achieved attention owing to their crystal structure and unique properties. BCN compounds are expected to combine excellent properties of diamond, B4C and BN with their properties adjustable depending on their composition and structure[1]. B-C-N ternary compounds has been reported previously for biological applications [2-5].

In this study, we investigate RF sputter deposited BCN films for biological applications. Bacterial contamination in biomedical field has several adverse effects. BCN coating may interfere with bacterial adhesion and reduce bacteria colonization. BCN films are deposited by reactive sputtering of B4C target in presence of nitrogen. Bacteria colonies are grown on BCN thin films and incubated for 24 hours.

[1] A. Prakash, S. D. Nehate, and K. B. Sundaram, "Boron carbon nitride based metal-insulator-metal UV detectors for harsh environment applications," Optics letters, vol. 41, no. 18, pp. 4249-4252, 2016.

[2] W. Yang, P. Thordarson, J. J. Gooding, S. P. Ringer, and F. Braet, "Carbon nanotubes for biological and biomedical applications," Nanotechnology, vol. 18, no. 41, p. 412001, 2007.

[3] A. Bianco, K. Kostarelos, C. D. Partidos, and M. Prato, "Biomedical applications of functionalised carbon nanotubes," Chemical Communications, no. 5, pp. 571-577, 2005.

[4] S. H. Mir, V. K. Yadav, and J. K. Singh, "Boron–Carbon–Nitride Sheet as a Novel Surface for Biological Applications: Insights from Density Functional Theory," ACS Omega, vol. 4, no. 2, pp. 3732-3738, 2019.

[5] G. Ciofani, S. Danti, G. G. Genchi, B. Mazzolai, and V. Mattoli, "Boron nitride nanotubes: biocompatibility and potential spill‐over in nanomedicine," Small, vol. 9, no. 9‐10, pp. 1672-1685, 2013.
Tunable Permselectivity in a Robust Anion Exchange Membrane for Electrodialysis
Authors: Wu Ivy , Kuo Mei-Chen , Herring Andrew M.
Published: February 2020

Ion exchange membranes are commonly used in many applications such as water desalination and wastewater nutrient recovery. The permselectivity of ion exchange membranes is one of its most critical properties, but often must be balanced with adequate permeability. High permeation of negative ions coupled with low permeation of positive ions is desirable in anion exchange membranes (AEMs). However, separation of these oppositely charged ions tends to suffer as the concentration of the feed solution increases, thereby limiting the range of processable feed solutions. In this work, a robust AEM was synthesized with a polychlorostyrene-b-polycyclooctene-b-polychlorostyrene ABA triblock polymer quaternized with methylpiperidine. By adjusting the block length of polychlorostyrene, different sized water channels are formed within the AEM which result in highly tunable anion selectivity. Small angle x-ray scattering (SAXS) and TEM confirm the size of these water channels while permeability and sorption tests elucidate the influence of these different morphologies on separation ability. The AEM also has low water uptake for increased stability and mechanical strength, which is vital in terms of extending the membrane lifetime. With this robust material, AEMs may enable the desalination of highly saline waters such as seawater and enable more economic wastewater nutrient recovery.
Hierarchical Nico Layered Double Hydroxidesnanosheets on Carbonized CNT/Cotton As a Highperformance Flexible Supercapacitor
Authors: Tianqi Hao , Wang Wei , Yu Dan
Published: February 2020

Flexible electrodes, unlike the traditional ones, are highly integrated and portable, have attracted great attention in modern electronics fields. They can be served as essential parts in flexible supercapacitors and are critical items in the energy storage system for intelligent electronic products and health monitoring system. The core criteria to design a qualified flexible supercapacitor are high flexibility, stability and capacitance.

Cotton fabric is a good choice owing to the properties like low price, easily available and hydrophilicity, in which the hydroxyl groups make it favorable for adsorbing water and reacting with active materials. Carbon nanotubes (CNT) are widely used electrode materials with the merits of high specific surface area, good chemical stability, low resistance, thermal stability, high flexibility and excellent electrical properties. However, it is hard to obtain ideal properties only combining carbon nanotubes with cotton, because the low capacity of carbon nanomaterials.

Layered double hydroxides (LDHs) are promising Faradaic materials for the construction of high-performance supercapacitors, due to their unique two-dimensional lamellar structures and remarkable stability. Herein, hierarchical porous NiCo LDHs integrated with flexible CNT/cotton fabric current collector, are realized by a facile method, which exhibits a high capacitance. Moreover, the hybrid electrode has been assembled into a flexible supercapacitor device with the cycling stability of 94% capacitance retention after 3000 cycles.

The better flexibility and conductivity of the CNT, and highly intrinsic electrochemical activity of the NiCo LDHs as well as the superiority of the interwoven structure are responsible for the outstanding performance of the supercapacitor. The elaborate structural design can provide new insights into the construction of high-performance flexible supercapacitors.

Figure 1
Electrochemical Properties of Silver-Zinc Secondary Battery
Authors: Jeong Jiung , Lee Jong-Won , Shin Heon-Cheol
Published: February 2020

The forthcoming green energy era strongly demands a next generation energy storage systems with much higher energy/power density, environmental friendliness, stability, etc. In relation to this, much effort has been made to explore the possible use of conventional primary battery in an electrically rechargeable form. Various alkaline batteries have been proposed as a candidate. Among this, silver-oxide battery draws a special attention because it has flat discharge voltage, high energy density (200 Wh/kg, 750 Wh/dm3) and superior rate performance. In addition, it is much safer and easier to recycle, as compared to lithium-ion batteries.

A silver-oxide battery is often called a silver-zinc battery when it is designed to be electrically rechargeable. Like its primary form, it is desirable to minimize the content of expensive silver, i.e., the design needs to be cathode-limited. Accordingly, the characteristics of silver-zinc battery might be strongly affected by the behavior of silver cathode. Based on the works on the silver anodization, it has been reported that silver is transformed to Ag2O and then AgO during anodic oxidation and the latter AgO formation needs relatively large driving force. In spite of many data on the anodization process of silver, however, there has been little information about the battery performance of silver-zinc secondary battery. Moreover, as far as we know, the systematic study on its electrochemical characteristics is extremely lacking.

The work provides an in-depth investigation of silver-zinc battery. In particular, the electrochemical properties and battery performance were systematically investigated at different charging/discharging rate, operating temperature, state of charge (SoC), etc. For this purpose, cathode-limited silver-zinc battery was fabricated using well-defined silver thin film and was analyzed by a variety of electrochemical techniques such as galvanostatic/potentiostatic methods, cyclic voltammetry, and impedance spectroscopy. From the combination of electrochemical, compositional, and structural analyses, the transformation of silver to Ag2O and AgO, and vice versa process was thoroughly investigated. For example, figure shows the SEM images and the corresponding XRD patterns of silver cathode at different SoCs. Porosity of products (Ag2O, AgO) gets increased with the SoC and the diffraction intensities of substrate and products are accordingly varied.

In this presentation, the charging/discharging mechanism of silver-zinc battery will be systematically explored and its uniqueness will be highlighted from the viewpoint of the kinetics of electrochemical reactions. Moreover, the cycling performance and the factors governing the capacity and efficiency degradation will be discussed.

Figure 1