bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of a Novel Bi-Functional Additive for High Voltage LiNi1.5Mn0.5O4/Graphite Cells
Authors: Kim Jongjung , Adiraju Venkata Aditya Kiran , Rodrigo Nuwanthi dilhari , Hoffmann Jennifer , Payne Martin , Lucht Brett L.
Published: December 2020

LiNi1.5Mn0.5O4 (LNMO)/graphite (Gr) cells are a promising candidate for commercial Li-ion batteries due to their high power density and low costs. However, the most challenging obstacle of LNMO/Gr cell is severe capacity fading at high temperature.1 The severe cell failure is associated with transition metal ion dissolution (Ni and Mn) from the positive electrode caused by acidic species, such as hydrogen fluoride, which is generated through the hydrolysis of lithium hexafluorophosphate by residual water in the electrolyte solution.2 The dissolved metal ions migrate through the electrolyte solution and deposit at the anode, where they cause a continuing deterioration and reformation of the solid electrolyte interphase,which results in an increasedcell resistance and steadily decreasing capacity utilization.

To suppress these issues, a novel bi-functional electrolyte solution additive has been synthesized and tested. LNMO/Gr cells containing the additive display a significantly improved capacity retention during high temperature cycling. The end-of-test of the harvested electrodes analysis indicates that the additive may act as HF scavenger and as film-forming agent on the graphite electrode.

Experiments

The 2032-type coin cells were fabricated with LNMO, graphite, separators (Celgard 2325, GF/D), and electrolytes. The standard electrolyte formulation is 1.2 M LiPF6 EC:PC:DEC=15:20:65 (v/v/v). The cells were pre-cycled five times at room temperature, followed by cycled seven times for the rate testing. And then, the cells were cycled for 100 cycles at 3.3-4.9V with a rate of 1 C at 45 ℃. Constant voltage steps were applied at the end of charge with 0.05 C cut-off.

Reference

D. Lu, M. Xu, L. Zhou, A. Garsuch, and B. L. Lucht, J. Electrochem. Soc., 160, A3138–A3143 (2013).

N. P. W. Pieczonka, Z. Liu, P. Lu, K. L. Olson, J. Moote, B. R. Powell, J. Kim, J. Phys. Chem. C, 117, 15947–15957 (2013).

Figure
1 (a) The discharge capacity and (b) capacity retention of LNMO/Gr cells at 45oC.

Figure 1
Manganese and Bismuth Electrodeposition from a Choline Chloride Based Deep Eutectic Solvents
Authors: Karar Youcef , Boudinar Salem , Kadri Aziz , Lepretre Jean-Claude , Benbrahim Nassima , Chainet Eric
Published: December 2020

The effect of different additives on manganese and bismuth electrodeposition from choline chloride-urea (Reline) and choline chloride-ethylene glycol (Ethaline) deep eutectic solvents (DESs) was investigated. Spectroscopic and thermal studies were performed on the latters in order to understand whether some additives affect the DESs behaviors. the results of the thermal study do not indicate any significant change except a small shift in the melting point of the reline when adding ammonium chloride (~+3°C) and the modification of a cold crystallization peaks at low scan rate. The electrochemical behaviors of manganese and bismuth were then studied by cyclic voltammetry. electrocrystallization was studied by chronoamperometry which has shown that the bismuth electrodeposition evolves with a 3D progressive nucleation. The current transients for Mn reveals that the presence of thiourea enhances the nucleation rate by modifying the corresponding nucleation and growth model from 3D progressive to 3D instantaneous. EDS analysis confirms that pure bismuth thin films were obtained and X-Ray diffraction indicates that the bismuth growth follows a preferential orientation along the (012) reticular plane. While for manganese, no metal phase was observed in diffraction due to the amorphous nature of Mn deposits. Annealing treatments will therefore be necessary.
Application of Artificial Interphase on Ni-Rich Cathode Materials in All Solid State Li-Ion Batteries
Authors: Liao Cheng-Hung , Jeng Ru-Jong , Wu Nae-Lih (Nick)
Published: December 2020

Among many cathode materials, nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM 811) has been spotlighted as one of the most feasible candidates for next-generation LIBs because of its high discharge capacity (~200 mAh/g). However, NCM 811 shows significant performance degradation, which is mostly attributed to cation mixing, surface side reactions, and intrinsic structural instability originating from the large volume changes during repeated cycling.

Conventional lithium ion batteries (LIB) normally use flammable nonaqueous liquid electrolytes, resulting in a serious safety issue in use. In this respect, all solid state lithium ion batteries (SSLIBs) are regarded as a fundamental solution to address the safety issue by using a solid state electrolyte (SSE) in place of the conventional liquid one.

This study assess the performance of NCM811 cathode for all-solid-state batteries based on hybrid PEO-ceramic solid electrolyte. Artificial CEI coating layer has been developed in order to prevent direct contact of electrolyte with the cathode, thus avoid the negative effects, such as side reactions, on NCM 811. The incorporation of ceramic materials results composite electrolytes, containing inert fillers, offer improved mechanical stability under high operating temperature.

It is demonstrated that the polymer of hybrid electrolytes can penetrate into cathode, providing a good Li+ transfer channel inside the battery under high operating temperature. Moreover, the protective coating on NCM811 effectively improve the electrochemical stability.

(This work is supported by Ministry of Science and Technology, Taiwan under contract number: MOST 108-3116-F002-008)
Interfacial Potentials in a Thin Film All-Solid-State Li-Ion Battery Probed By in Operando KPFM
Authors: Strelcov Evgheni , Fuller Elliot James , Weaver Jamie Lynn , Swift Michael , Kolmakov Andrei , Zhitenev Nikolai , Qi Yue , McClelland Jabez J. , Dura Joseph A. , Talin A. Alec
Published: December 2020

Designing smaller, safer, cheaper, and more stable batteries necessitates thorough understanding of the electrochemical processes governing their operation at multiple length scales. In all-solid-state power sources the electrolyte is no-flammable and can be made ultimately thin, making them safer and more compact. Yet, experimental evidence suggests that the multiple internal interfaces in their layered structure give rise to high impedances, limiting their performance. Studying these nanoscopic interfaces requires microscopic tools. Here, we employ in operando Kelvin Probe Force Microscopy (KPFM) to quantitatively measure the potential distribution in a solid-state Li-ion battery as a function of its state of charge. The battery was fabricated by sequentially depositing thin layers of Pt (110-130 nm), LiCoO2 (280-420 nm), LIPON (1100-1200 nm), Si (50-240 nm) Cu or Pt (150-200 nm) onto a Si/SiO2 wafer (oxide thickness 100 nm). The fabricated battery was cleaved in an Ar atmosphere to expose the stacked layers, mounted on a holder, wired, and safely transferred without exposing to air into a dual-beam instrument that combines a scanning electron microscope (SEM), a Ga-ion focused ion beam (FIB) and an atomic force microscope (AFM) in one vacuum chamber (residual pressure of 10-4 Pa). The stacked battery was milled to expose a cross-section of the layers, and imaged using SEM and KPFM, while cycling the battery. The acquired potential maps reveal a highly non-uniform interelectrode potential distribution, with most of the potential drop occurring at the electrolyte-Si anode interface in the pristine battery. During the first charge, the potential distribution gradually changes, revealing complex polarization within the LIPON layer due to Li-ion redistribution. Cycling the battery at high rate significantly decreased its capacity, although the capacity loss can be recovered. KPFM imaging allowed the detection of the interface responsible for this capacity loss. Li distribution in the battery was also measured using Neutron Depth Profiling as a function of the state of charge. The acquired data was compared to first principles calculations shedding light onto the interfacial Li-ion transport in the battery and its reversibility.

ES acknowledges support under the Cooperative Research Agreement between the University of Maryland and the National Institute of Standards and Technology Center for Nanoscale Science and Technology, Award 70NANB14H209, through the University of Maryland.
BiSbWO6: Band Energies Tuning of a Mixed Sb(5s)/Bi(6s) Lone-Pair-Electrons System
Authors: Bainglass Edan , Walsh Aron , Huda Muhammad N.
Published: December 2020

Post-transition metal oxides with electronic configuration ns2-md0 have been highlighted as efficient photocatalysts due to their favorable optoelectronic properties. Of the ns2-md0 class of materials, none have received greater attention than BiVO4. Due to the localized V 3d conduction orbitals, BiVO4 charge transport properties are affected by the formation of small polaronic states. Alternatively, one may consider materials with more delocalized conduction bands, such as W 5d0 compounds. One such example is the russellite mineral, or Bi2WO6. Density functional theory is used to calculate the electronic properties of Sb-alloyed Bi2WO6, and to study the effects of introducing Sb 5s orbitals to the band structure. In studying the configurational space of BiSbWO6, we provided new insights into the behavior of mixed Sb(5s)/Bi(6s) lone-pair electrons in post-transition metal oxides. We find that local distortions caused by Sb 5s lone-pair electrons indirectly lead to upshifts in both valence and conduction band edges. To isolate the role of the lone pairs, we compare the observed effects to those in a WO3 control model that is subject to structural deformations. These insights may be further extended and applied more generally to mixed post-transition metal oxides in pursuit of new efficient solar absorbing materials.
Interpreting Ionic Conductivity for Polymer Electrolyte Fuel Cell Catalyst Layers with Electrochemical Impedance Spectroscopy and Transmission Line Modeling
Authors: Qi Yongzhen , Liu Jiangjin , Sabarirajan Dinesh C , Huang Ying , Perego Andrea , Haug Andrew Thomas , Zenyuk Iryna V.
Published: December 2020

An optimal cathode catalyst layer with uniform ionomer distribution is critical to reduce the platinum loading and increase the utilization in polymer electrolyte fuel cells (PEFCs). Having well distributed ionomer with low ionomer to carbon (I/C) ratio is desirable, as it will also minimize local oxygen transport resistance. In this work, we used electrochemical impedance spectroscopy (EIS) method and transmission line model (TLM) to measure and evaluate ionic conductivity of pseudo catalyst layers (PCLs) comprised of Vulcan XC72 carbon black and 3M 825 EW ionomer with I/C ratios of 0.3, 0.6, 1 and 1.4 at a relative humidity (RH) range of 50 to 120 %. These results were compared with our previous hydrogen pump (HP) measurements, where PCL was sandwiched between the two membranes and protons had to transport through the entire PCL to be counted towards current. EIS effective ionic conductivity results reported here are higher than the results of HP because in the HP set-up ionic pathways must percolate all the way through the PCL to be effectively counted, whereas in EIS measurement, ionomer segments that are in contact with the membrane but not percolating all the way through the PCL can be detected. Additionally, three effects were studied: 1) hot press, 2) platinum content and carbon black support, and 3) ionomer content or lack of ionomer. Ionic conductivity increased significantly by hot pressing PCL onto the membrane, however, it was independent with respect to the hot press conditions, such as pressure and temperature. Hot pressing with low I/C ratio had more impact than high I/C ratio because at high I/C ratio even without hot press there is a sufficient amount of contact points between catalyst layer and membrane. At high RHs, catalyst layer containing Pt has higher ionic conductivity compared to PCL because of Pt particles being hydrophilic, which helps to distribute the ionomer more uniformly. To investigate the effect of condensed water, PTFE dispersion was used as a binder for Pt/C layer instead of ionomer, resulting ionic conductivity decreased with increasing applied potential at 100% and 120% RH conditions. At lower RHs, ionic conductivity is independent of the applied potentials.
Pore Network Modeling of Microporous Layers for Polymer Electrolyte Fuel Cells
Authors: Shintaro Iwasaki , Nakajima Hironori , Kitahara Tatsumi
Published: December 2020

Liquid water accumulated in the catalyst layer (CL) and gas diffusion layer (GDL) of a polymer electrolyte fuel cell (PEFC, PEMFC) results in performance deterioration due to inhibition of oxygen transport to the cathode CL (Flooding). To enhance the drainage in the GDL, the application of a microporous layer (MPL) is effective to the CL side of the GDL substrate [1, 2]. To elucidate the effects of two-phase flow on the oxygen transport in an MPL for its optimized designs, we model three dimensional porous structures of in-house MPLs with pore network model (PNM) [3, 4] for convective air permeation and oxygen diffusion. Pore diameter distribution derived by a focused ion beam scanning electron microscope (FIB-SEM) is employed in the PNM. Air permeation measurements combined with oxygen diffusion measurements with changing wetting liquid saturation (Galwick, Porous Materials Inc., USA) by using gas chromatography validate the model.

Acknowledgments

The authors are indebted to graduate students, Messrs. Yuhang Liu, Kentaro Harano, Dingfeng Chen for help in the modeling and experiment. Thanks are offered to Professor Kohei Ito of Kyushu University for valuable discussions. The authors acknowledge Ms. Chie Uryu of International Research Center for Hydrogen Energy, Kyushu University for operating the FIB-SEM.

References

Nakajima H, Konomi T and Kitahara T. 2007. Direct water balance analysis on a polymer electrolyte fuel cell (PEFC): Effects of hydrophobic treatment and micro-porous layer addition to the gas diffusion layer of a PEFC on its performance during a simulated start-up operation. Journal of Power Sources 171: 457-463.

Kitahara T, Konomi T and Nakajima H. 2010. Microporous layer coated gas diffusion layers for enhanced performance of polymer electrolyte fuel cells. Journal of Power Sources 195: 2202-2211.

Gostick J, Aghighi M, Hinebaugh J, Tranter T, Hoeh MA, Day H, Spellacy B, Sharqawy MH, Bazylak A, Burns A, Lehnert W and Putz A. 2016. OpenPNM: A pore network modeling package. Computing in Science & Engineering 18: 60-74.

http://openpnm.org/. Accessed on September 14, 2020
Digital Processing of the Different Operating Modes of a PEM Electrolyser Viafast Camera
Authors: Rohe Julien , Lin Kwong Chon Christophe , Boulevard Sebastien , Damour Cedric , Grondin-Perez Brigitte , Kadjo Jean-Jacques Amangoua , Bessafi Miloud
Published: December 2020

One way of increasing the efficiency of the polymer electrolyte membrane is to study two-phase flow effects in order to improve the evacuation of the product of the reaction, namely the water in fuel cells [1] and the dioxygen in the electrolyser [2]. The analysis of the water evacuation in PEMFC has been studied extensively [3], but the formation and the evacuation of dioxygen in PEMWE are not yet systematic. We propose to detect water bubbles through 3 actions in order to observe and identify dioxygen bubbles. Firstly, the image segmentation via morphological processing to create a sketchily data set. This approach has some limits, such as size or shape detection. Therefore, for a second stage a training of a shape regression convolutional neural network is used to estimate shape and complex forms [4]. And finally, the last action a validation of the neural model in online and real-time is provided. We hope that this work will help further studies, allowing to link shape, frequency, residence time, and velocity of bubbles of the different parameters used with electrolyser.

Figure 1: Detection and regression shape of dioxygen bubble through CNN

REFERENCES

1. Y. Ding, X.T. Bi, D.P. Wilkinson, Numerical investigation of the impact of two-phase flow maldistribution on PEM fuel cell performance, International Journal of Hydrogen Energy, Volume 39, Issue 1, 2014

2. F. Aubras, J. Deseure, J.-J.A. Kadjo, I. Dedigama, J. Majasan, B. Grondin-Perez, J.-P. Chabriat, D.J.L. Brett,Two-dimensional model of low-pressure PEM electrolyser: Two-phase flow regime, electrochemical modelling and experimental validation,International Journal of Hydrogen Energy,Volume 42, Issue 42,2017, Pages 26203-26216.

3. J.G. Carton, V. Lawlor, A.G. Olabi, C. Hochenauer, G. Zauner, Water droplet accumulation and motion in PEM (Proton Exchange Membrane) fuel cell mini-channels, Energy, Volume 39, Issue 1, 2012

4. Tim Haas, Christian Schubert, Moritz Eickhoff, Herbert Pfeifer, BubCNN: Bubble detection using Faster RCNN and shape regression network, Chemical Engineering Science, Volume 216, 2020.

Keywords: PEMWE, high-speed camera, bubble gas tracking, CNN, segmentation

Figure 1
Fast Charge Transfer between LLZO Solid Electrolyte and LCO Cathode Thin Films with a Modified Interface
Authors: Sastre Jordi , Chen Xubin , Aribia Abdessalem , Tiwari Ayodhya N. , Romanyuk Yaroslav E.
Published: December 2020

Thin film deposition of solid electrolytes can be useful for the fabrication of better solid-state batteries by reducing the thickness of the electrolyte material to a few hundred nanometers. This facilitates ionic conductance for faster charge-discharge and reduces the total volume of inactive material, therefore increasing energy and power density. Thin film batteries can also be valuable model systems to investigate interface charge dynamics and to serve as playgrounds for interface engineering, without the complexity of bulk systems. Here we investigate the charge transfer properties between the lithium garnet Li7La3Zr2O12 (LLZO) solid electrolyte and the LiCoO2 cathode using a thin-film model system, with the aim of reducing the interface resistance and allowing high charge-discharge rates.

Bulk LLZO electrolyte has come under the spotlight owing to its high ionic conductivities (10-4 - 10-3 S/cm) as well as a wide electrochemical stability window (against metallic lithium anode and high potential cathode materials). We developed a method for fabricating crystalline LLZO thin films using magnetron co-sputtering followed by an annealing step at 700°C (significantly below the standard processing temperatures). The resulting 500 nm-thick Ga-doped LLZO thin films show densities and ionic conductivities (2×10-4 S/cm) comparable to the values observed in bulk ceramic pellets.[1]

Based on this thin film fabrication process, we fabricated an all-thin-film model system to investigate the LLZO / LCO cathode interface. This architecture provides an easy access to the interface for characterization, allowing one to identify the degradation processes taking place at the interface under high-temperature co-sintering. Introducing an in situ-lithiated Nb2O5 diffusion barrier at the interface, it was possible to lower the LLZO / LCO charge transfer resistance to about 50 Ω cm2, a 3-fold reduction with respect to previously reported values. The low interfacial resistance combined with the high conductance through the LLZO thin-film electrolyte allows charge transfer at high charge–discharge rates up to 40 C (0.9 mA/cm2).[2]

References

[1] Sastre, Jordi, et al. "Lithium Garnet Li7La3Zr2O12 Electrolyte for All‐Solid‐State Batteries: Closing the Gap between Bulk and Thin Film Li‐Ion Conductivities." Advanced Materials Interfaces (2020): 2000425.

[2] Sastre, Jordi, et al. "Fast Charge Transfer across the Li7La3Zr2O12 Solid Electrolyte/LiCoO2 Cathode Interface Enabled by an Interphase-Engineered All-Thin-Film Architecture." ACS Applied Materials & Interfaces 12.32 (2020): 36196-36207.
Electrochemical Monitoring and Evaluation of Metallo-Quercetin Complexes’ Antioxidant Activity Toward Electrochemically Generated Superoxide Anion Radical
Authors: Lewis Tyra , Martic Sanela
Published: December 2020

The superoxide anion radical, O2˙– (SAR) is a reactive oxygen species (ROS) that is naturally generated within the biological environment via a one electron reduction of molecular oxygen.1-4 Excess production of ROS in the body can lead to undesired reactions that induce cellular death and furthermore, the onset of some pathological diseases.1,3 Antioxidants, such as flavonoids, react with ROS to prevent possible cell damage and development of health issues caused as a result of excess ROS production.2,3 Additionally, flavonoids, such as quercetin (QCR), are known to play a role as metal ion chelators.3,4 Biologically relevant metal ions are also known to influence the activity of ROS via Fenton reactions.3 However, the coordination of metal ions with QCR results in the formation of a metallo-QCR complex that may influence the antioxidant activity and capacity of the flavonoid. The role of metal ions and metallo-QCR complexes as antioxidants toward SAR is not fully understood. Electrochemistry is a valuable analytical tool that can be used to study and assess the reactivity of metal ions and polyphenolic compounds with SAR.1-4

In this work, we monitored and evaluated the ability of QCR and biologically relevant metal ions, Fe(III) and Cu(II) to influence the activity of electrochemically generated SAR. Additionally, we tested and compared the reactivity of metallo-QCR complexes prepared either by sequential addition of metal ion, followed by QCR (in-situ) or by direct addition of a preformed mixture to the electrochemically generated SAR. Specifically, 1:1 and 1:2 molar ratios of metal ion:QCR were explored. The O2˙–/O2 redox couple was generated in-situ using a three-electrode electrochemical cell, with a glassy carbon electrode, a platinum wire counter electrode and a Ag/AgNO3 reference electrode immersed in DMF.1 Using cyclic voltammetry (CV), the current and potential associated with the O2˙–/O2 redox couple was monitored and measured to assess radical scavenging ability of the additives of interest. The data revealed a decrease in SAR associated peak currents for all additives, indicating their role as free radical scavengers. CV data also suggested that the reaction between QCR, metal ions and metallo-QCR complexes is driven by an initial electron transfer mechanism that is followed by a proton transfer.2 Overall, compared to all other variations of additives tested, in-situ prepared 1:2 Cu:QCR complexes exhibited the greatest ability as antioxidants toward SAR.

References

N. L. Zabik, S. Anwar, I. Ziu, and S. Martic-Milne, Electrochim. Acta,
296, 174-180 (2019).

Ahmed, F. Shakeel, Czech J. Food Sci., 30, 153-163 (2012).

E. Bodini, G. Copia, R. Tapia, F. Leighton, and L. Herrera, Polyhedron, 18, 2233-2239 (1999).

M. Kasprzak, A. Erxleben, J. Ochocki, RSC Adv., 5, 45853-45877 (2015).
Mimicking Photoredox Catalysis Using Electrochemistry for Organic Synthesis
Authors: Luo LONG
Published: December 2020

Photoredox catalysis and electrochemical organic synthesis are two emerging fields in organic chemistry. Inspired by the similarity between single electron transfer events in photoredox catalysis and half-reactions in electrochemistry, we developed a new electrochemical approach that mimics the photoredox catalysis for organic synthesis. We demonstrated using this approach for electrochemical trifluoromethylation of arenes and heteroarenes. We also established a theory for guiding the rational design of reaction conditions. Our approach will open a new avenue at the intersection of photoredox catalysis and electrochemical organic synthesis.
CdS Sensitized Solvothermal Phase Change Assisted Synthesis of CoTiO3 @ TiO2 Nanorods As a Ternary Heterojunction Photoanode for Photoelectrochemical Water Splitting
Authors: Maitra Soumyajit , Maitra Toulik , Pal Subhan , Roy Subhasis
Published: December 2020

Development of efficient semiconductor heterostructures with adequate band alignment for enhanced charge separation and increased light absorbance has been at the forefront of research on photoelectrodes. In this work we demonstrate the fabrication of CdS sensitized CoTiO3 @ TiO2 photoanodes for photoelectrochemical water splitting. TiO2 nanorods were synthesized by a hydrothermal method followed by surfactant assisted solvothermal impregnation of Co2+ ions into the TiO2 lattice resulting in development of a core-shell CoTiO3 @ TiO2 p-n junction heterostructure. The photoanodes were further sensitized by CdS nanoparticles by a facile SILAR method not only to increase light absorbance in the visible region but also to form a ternary heterojunction photoanode with cascade type electron transfer. The fabricated photoanodes showed an ABPE % of 0.43% at 0.6 V vs Ag/AgCl reference electrode using 0.5 M Na2S and 0.5M Na2SO3 electrolyte under A.M 1.5 G simulated solar illumination. Optical properties were analyzed using UV-Vis Absorbance and Photoluminescence Spectroscopy. Transient photocurrent, EIS and Mott-Schottky analysis were carried out to analyze charge transport processes occuring at the semiconductor / electrolyte interface. Structure and morphological analysis was carried out using XRD and FESEM. Band structure and DOS was analyzed using DFT calculations.This work hopes to inspire new research in development of ternary heterojunctions for photoelectrochemical water splitting.
Fluoride Electrosorption By an Activated Carbon Doped with Lanthanum
Authors: Martinez-Vargas D. Ricardo , Rangel-Mendez J. Rene , Cházaro Luis
Published: December 2020

Fluorine is an essential element for human health at low doses, but its excessive and chronic consumption at higher doses promotes undesired health conditions. This research reports the electrosorption of fluoride with a commercial bituminous activated carbon impregnated with Lanthanum, as Lanthanum is an excellent fluoride sorbent and presents interesting electrochemical properties. The impregnation was performed in a doping concentration to avoid significant changes in the textural (surface area and pore volume) and capacitive properties (by cyclic voltammetry) of the modified carbon. SEM-EDS mappings were used to evaluate La(III) impregnation and dispersion on the carbon surface, and ICP-OES, to determine its content (0.45% w/w). The anchoring of La(III) modified abruptly the physicochemical properties of the carbon surface, decreasing its point of zero charge (pHPZC) from 8.5 to 4.9, and increasing its potential of zero charge (EPZC) from 0.0 V to 0.3 V (vs. Ag/AgCl/3M NaCl). This was attributed to the exposed hydroxyls from La(III) clusters, which present a Bronsted-acid character and can deprotonate as function of the solution pH. The carbon performance was evaluated by two polarization profiles: stepped-potential increases and single potentials applied from the beginning (0.4, 0.8 and 1.2 V vs. Ag/AgCl/3M NaCl). The anodic polarization of the carbons increased their removal capacity and velocity towards fluoride and a similar capacity was reached independently of the polarization profile, for most applied potentials. At 1.2 V (C0 = 20 ppm F-, pH0 = 7) the removal of the modified carbon increased 2.55 times, compared to its adsorption capacity without polarization (5.93 vs. 2.33 mg g-1, respectively), while the pristine carbon reached only 4.26 mg g-1 . Desorption by depolarization was inefficient for the modified carbon but was attained by reversing the polarization to -0.5 V (94% and 51% desorption for the pristine and modified carbon, respectively). This was due to fluoride chemisorbed to the modifed carbon surface by a ligand-exchange mechanism, in which the exposed hydroxyls provided by La(III) clusters were exchanged by fluorides in solution. Surface charges (pHPZC and EPZC) played a major role in explaining the obtained capacities and velocities, as has been widely studied and reported in desalination using the amphoteric Donnan model.
(Invited) Can a “Bad” Salt be a Good Salt for Li Metal Batteries
Authors: Dumaz Philippe , Sergent Nicolas , Benayad Anass , Pagnier Thierry , Lecuyer Margaud , Deschamps Marc , Bouchet Renaud
Published: December 2020

Ethylene oxides (EO) based electrolytes are commonly used for their relatively good stability face to lithium metal. These ethers allow a good dissociation and solvation of lithium salts such as the commonly used LiTFSI salt. However, the EO/LiTFSI complexes if they show quite good conductivities, their transport number is quite low, and the TFSi anions do not give very good Solid electrolyte interphases (SEI) which implies quite poor performance vs lithium metal anodes. By replacing the salt by LiNO3, we observed an outstanding improvement in the cyclability of symmetrical Li cells, even at rather high current density (i. e. above 1 mAcm-2). To understand this improvement, we first compared the ionic transport properties of LiNO3 versus LiTFSI salt in small glymes (molar mass = 240 g mol-1). At 40°C, PEG laden with 1M LiNO3 present an ionic conductivity one order of magnitude lower than LiTFSI, but the Li+ transport number is very high at 0,87. From ab initio calculation, Raman spectroscopy and NMR, we demonstrate that LiNO3 is only partially dissociated and tends to form dimers (or more) with lithium ion. These anionic complexes are not very mobile, which explains the lower conductivity and higher lithium ion transport number. Then, by mean of XPS and EIS, the composition and electrical properties of the SEI formed on lithium metal were obtained and compared. Finally, the lithium electrodeposits morphologies were characterized by X-Ray micro-tomography and SEM, allowing us to have all the cards in hand to explain the far better performance of the LiNO3 salt vs LiTFSI salt.
Evaluation of Properties of DNA Methyltransferase M. Ape from Hyperthermophilic Archaea Aeropyrum Pernix
Authors: Hayashi Mao , Iida Yasuhiro
Published: December 2020

DNA methylation is one of the epigenetic modifications that have significant functions in eukaryotic cells such as regulation of gene expression and imprinted gene. Also, it has significant functions in prokaryotes such as R-M system, regulation of cell cycle and mark to daughter strand in the DNA replication. DNA methyltransferase exists in eukaryotic, prokaryote and archaea. However, N5-cytosine DNA methyltransferase from hyper-thermophilic archaeon hasn’t reported. In our laboratory, we focus on methyltransferase M. Ape from hyper-thermophilic archaeon. This enzyme is estimated to have characteristics of thermostability. If it reveals to the characteristics of M. Ape that we will be able to apply to new technology. In this study, we investigated the recognition sequence and the position of the modified methyl group.

At first, we performed alignment analyses M. Ape and N5-cytosine methyltransferase from eukaryotic. As a result, we observed it has the common motif of N5-cytosine methyltransferase. And then, we determined the recognition sequence of M. Ape. In this experiment, 7 kinds of the substrate as Oligo DNA were used. We evaluated the recognition sequence from the activity of methyltransferase against these substrates. As a result, GCWGC sequence was the most reactive substrate against M. Ape. Further, as a result of bisulfite sequencing, it was clarified APE_0872 modified the methyl group to the second cytosine of GCWGC.

Furthermore, we tried the determination of the position of the methyl group to cytosine by M. Ape with use for HPLC. The column (InertSustain AQ-18) was used for the separation and the flow rate was 1.0 mL/min. We used 0.1 % formic acid in water(A) and 0.1 % formic acid in methanol (B), buffer B was increased with linear gradient 1.5 %/min from 0 % to 22.5 %. The peak from the sample was observed similarly retention time of 5mC of authentic samples. Thus, it was suggested that M. Ape modify N-5 cytosine.
Development of Self-Powered Glucose Biosensors for Fish Stress Monitoring
Authors: WU Haiyun , Shen Lihang , Ohnuki Hitoshi , Endo Hideaki
Published: December 2020

Some biosensor systems which can make real-time monitoring of fish stress (glucose levels as the stress indicator) were developed in our laboratory. However, since these systems use a button battery as the power source, it requires regular battery replacement, which leaves some problems such as unnecessary handling stress on the fish and hindrance to continuous measurement due to interruption of measurement. In this study, we tried to develop a novel biosensor system that integrated the sensor (glucose biosensor) and power source (biofuel cell) to achieve a “Barrier-free Measurement” without battery replacement.

This sensor is powered by a biofuel cell that uses glucose as a substrate. On the other hand, the principle of the detection of glucose is based on quantifying glucose from the fluctuations in the current value obtained from the enzyme reaction. First, a self-powered glucose biosensor (Sensor 1) with a carbon rod as an electrode and neutral red as a mediator was developed, and the power generation characteristics and quantitative characteristics of the sensor were evaluated. The power generation characteristics were evaluated by the operating voltage calculated from the linear sweep voltammetry curve using an electrochemical analyzer. The quantitative characteristics were evaluated by gradually increasing the glucose concentration in the plasma sample of Nile tilapia (Oreochromis niloticus) and analyzing the relationship between the glucose concentration and the output current value of the sensor using a potentiostat. Furthermore, to improve the performance of the sensor, we manufactured another type of sensor (Sensor 2) that introducing a new carbon electrode material and carbon nanotubes (CNT). Then, the characteristics of the sensor during power generation and quantification were also evaluated.

The power generation characteristics of Sensor 1 showed an operating voltage of 295 µV cm-2 at a glucose concentration of 100 mg dL-1, which as a virtual critical point of fish stress. Besides, it was confirmed that the output current value of the sensor increased as the concentration increased in the glucose concentration range of 46.3 to 150 mg dL-1 in the plasma sample. On the other hand, Sensor 2 showed an operating voltage of 90 mV cm-2 at a glucose concentration of 100 mg dL-1, which was about 300 times the value compared with the former sensor. Furthermore, during glucose quantification, the measurable range in fish plasma samples expanded to 200 mg dL-1, which is a relatively acceptable measurement range for fish stress monitoring. Also, the S/N ratio of the Sensor 2 was also improved by 2.5 times compared with Sensor 1. These findings are suggested that our proposed sensor system, especially Sensor 2, could be applied to fish in the future after miniaturization and intensification.
Scanning Electrochemical Microscopy (SECM) for Accelerated Screening of CO2 Electroreduction to Formate Catalyst
Authors: Desilets-Mayer Francis , Hosseini-Benhangi Pooya , Sanchez-Sanchez Carlos , Asselin Edouard , Gyenge Elod
Published: December 2020

CO2 electroreduction to formate (CO2RF) is the key reaction in many renewable energy storage schemes, sequestering CO2 into a formate solution at ambient condition1. However, CO2RF catalysts are still afflicted by poor selectivity and low activity2,3. Compounding the issue, CO2RF catalyst screening is still dominated by slow, one catalyst sample at a time experimental method. Theoretical catalyst screening is also affected, with increasingly faster computational models waiting for sluggish empirical validation4. Our objective is to develop scanning electrochemical microscopy (SECM) as a high-throughput CO2RF catalyst screening tool using multi-catalyst arrays. Our SECM method was tested on arrays of Sn/SnOx catalysts (x = 1,2), evaluating the effectiveness of pre-electroreduction treatment on final activity. Theoretically, SnO/SnO2 mixtures are the most promising catalysts for CO2RF , but in practice, they are thermodynamically unstable at potentials at which aqueous CO2 reduction takes place5,6. Sn/SnOx catalyst pre-electroreduction at −1.25 VAg/AgCl yielded an agglomerated surface with increased SnOx composition and CO2RF activity. Conversely, pre-electroreduction at −3 VAg/AgCl deposited a film of nanoparticles (≈70μm) on the surface but decreased CO2RF activity and SnOx composition. In a single SECM experiment, the CO2RF activity of unreduced Sn/SnOx surface and of the two reduced surfaces was determined, demonstrating the technique’s potential for accelerating CO2RF catalyst screening. We will also discuss the advantages and challenges of using SECM for high-throughput CO2 reduction catalyst study.

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S. Wang, J. Wang, and H. Xin, Green Energy Environ., 2, 168–171 (2017).

Figure 1
New Procedure for Detecting Pesticides By Activating SERS Properties of Screen-Printed Electrodes
Authors: Fanjul Pablo , Ibáñez David , Caldevilla-Collado Paula , González-García María Begoña , Hernández-Santos David
Published: December 2020

The lack of sensitivity traditionally associated with Raman spectroscopy has limited the development of new analytical applications. However, enhancement of Raman intensity due to the electrochemical surface-enhanced Raman scattering (EC-SERS) effect is an interesting alternative to overcome this limitation. Although different analytical methods have been used in the detection of pesticides, the complicated instrumentation and the long procedures employed lead to the development of new and easy methodologies for quick detection.

EC-SERS methodology proposed in this work for the detection of different pesticides uses metal SPEs as SERS substrates but also includes a preconcentration step as essential stage. After that, SPEs are electrochemically activated by cyclic voltammetry. Sensitivity of the methodology proposed in this work provides interesting results that allows us the detection of different pesticides. Particularly interesting are the results obtained in the detailed analysis of Raman bands of thiram and imidacloprid. Their characteristic bands allow the detection of 2.4 ppb thiram and 25 ppb imidacloprid.

Figure 1. Raman spectra of thiram, imidacloprid, malathion and chlorpyrifos obtained by EC-SERS procedure using metal SPE.

Figure 1
A Proposed General Solution for Li Dendrite Penetration into Solid Electrolytes
Authors: Qi Yue , Ban Chunmei , Harris Stephen J
Published: December 2020

We propose a general solution to the problem of Li dendrite penetration through solid electrolytes such as LLZO. The solution is based on an analogy of Li dendrite penetration to stress corrosion cracking, a process in which a very soft material--water--penetrates through a very hard material--steel--generally at grain boundaries. The problem of stress corrosion cracking was solved many years ago by putting the surface into a state of residual compressive stress. A variety of materials have been strengthened this way, including metals, glasses (e.g., Gorilla glass), and ceramics. However, for this approach to be useful, it is critical, at a minimum, that the presence of a significant residual compressive stress not block ion transport. In this work, we used DFT to show that isotropic compressive residual stresses as high as -10 GPa—the maximum observed in strengthened ceramics—have only a minimal impact on the diffusion rate of Li+ ions through a near-surface region of LLZO.

Figure 1
Poly(ethylene oxide)-Based Electrolyte for Solid-State-Lithium-Batteries with High Voltage Electrodes: Re-Evaluation of Common Beliefs
Authors: Kasnatscheew Johannes , Homann Gerrit , Stolz Lukas , Winter Martin
Published: December 2020

Poly(ethylene oxide) (=PEO)-based solid polymer electrolytes (SPEs) are believed to be oxidatively instable, thus suitable only with “low potential” electrodes. Indeed, they reveal a sudden failure in Li metal cells when high potential positive electrodes, e.g. LiNi0.6Mn0.2Co0.2O2 (NMC622) are used. This is electrochemically detectable in an arbitrary, time – and voltage independent, “voltage noise” during charge.

A relation with the believed SPE oxidation was evaluated, for validity reasons on different electrodes including different active materials in both, potentiodynamic and galvanostatic experiments. The results indicate an exponential current increase and a potential plateau at 4.6 V vs. Li|Li+, respectively, demonstrating that the oxidation onset of the SPE is above the used working potential of NMC622, which is only charged up to 4.3 V vs. Li|Li+.

Surprisingly, a simple increase in SPE membrane thickness or a simple exchange of Li metal negative electrode with graphite electrode revealed an operation free of “voltage noise”. These experiments indicate that the Li | SPE interface, and in particular, Li dendrite formation and penetration through the SPE membrane is the significant source and counterintuitively not the literature believed SPE│NMC622 interface.(1) The concluded oxidative stability of the cheap and abundant PEO and the precisely diagnosed failure source led to modified and more systematic improvement strategies for a successful high voltage application of solid-state Li batteries, even at 40 °C.(2)

G. Homann, L. Stolz, J. Nair, I. C. Laskovic, M. Winter and J. Kasnatscheew, Sci Rep, 10, 4390 (2020).

G. Homann, L. Stolz, M. Winter and J. Kasnatscheew, iScience, [accepted] (2020).

Figure 1
Fast Determination of the Limiting Ionic Diffusion Coefficient in Lithium Metal Polymer Batteries
Authors: Devaux Didier , Leduc Hugo , Dumaz Philippe , Lecuyer Margaud , Deschamps Marc , Bouchet Renaud
Published: December 2020

The energy conversion and its storage is a tremendous challenge for our society. Despite the great progress of the Lithium (Li)-ion technology based on flammable liquid electrolyte, their intrinsic instability is a strong safety issue for large-scale applications. The use of solid polymer electrolytes (SPEs) is an adequate solution in terms of safety and energy density thanks to their stability towards Li metal.[1] Moreover, as for conventional liquid electrolyte, the cationic transference number of poly(ethylene oxide) based SPE is typically below 0.2 which limits their power performance due to the formation of concentration gradient throughout the electrodes.[2] In such Li metal battery, the SPE acts as both separator and functionalized cathode binder ensuring ionic transport all over the battery. To increase the battery energy density a simple way is to use thicker cathode. Indeed, for a given electrode formulation, the energy density is directly linked to the active material loading.[3]

The goal of this study is to propose a quick and efficient methodology to optimize the thickness of the SPE and of the cathode based on charge transport parameters, which allows to determine the effective limiting Li+ diffusion coefficient. Revisiting a protocol by Doyle et al.[4] the battery power performance is rapidly established, at least 8 time faster than conventional cycling (charge-discharge steps) with a similar accuracy as depicted in Figure 1.[5] Then, by using an approach based on the Sand equation a limiting current density is determined. A unique mother curve of the capacity as a function of the limiting current density is obtained whatever the electrode and electrolyte thicknesses. Finally, the effective limiting diffusion coefficient is estimated which in turn allows to design the best electrode depending on electrolyte thickness.

References

[1] J.-M. Tarascon, M. Armand, Nature, 414 (2001) 359.

[2] M. Doyle, T. F. Fuller, J. Newman, Electrochim.
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[3] Z. Du, Z., D. L. Wood III, C. Daniel, S. Kalnaus, J. Li, J. Appl.
Electrochem., 47 (2017) 405.

[4] M. Doyle, J. Newman, J. Reimers, J. Power Sources, 52 (1994) 211.

[5] D. Devaux, H. Leduc, P. Dumaz, M. Lecuyer, M. Deschamp, R. Bouchet, Front. Energy Res., 7 (2020) 168.

Figure 1
In Situ Synchrotron Radiation XRD and XAFS Measurements of Multilayer All-Solid-State Lithium-Ion Batteries Using Li2CoP2O7 as a Positive Electrode Material
Authors: Yamamoto Chihiro , Doi Shuichi , Nakanishi Masanori , Kobayashi Masakazu , Inagaki Masayuki , Goto Yuji , Kato Juji , Yamamoto Keita , Kato Akihiko , Kataoka Yuji
Published: December 2020

All-solid-state lithium-ion batteries are expected as next-generation batteries due to their safety and high volumetric energy density. We reported Li2CoP2O7 (LCPO) as a positive electrode material with charge/discharge reactions over 5 V. [1–3] In this study, the structural and valence change of LCPO in multilayer all-solid-state lithium-ion batteries during charge/discharge was investigated using in situ synchrotron radiation X-ray diffraction (XRD) and X-ray Absorption Fine Structure (XAFS) measurements.

In multilayer all-solid-state lithium-ion batteries, LCPO was the positive electrode active material, Ti-based oxide was the negative electrode active material, and NASICON-type solid electrolyte was used as the solid electrolyte. Each material for the positive and negative electrodes and the solid electrolyte was made into a paste. They were laminated using a screen printing method and integrally sintered to produce multilayer all-solid-state batteries. Synchrotron radiation XRD and XAFS measurements were performed at the large synchrotron radiation facility SPring-8. In situ XRD was measured in a transmission mode using 30 keV X-rays for a multilayer all-solid-state battery. The X-ray beam had to pass through the center of the multilayer all-solid-state battery during the first charge/discharge reactions. In situ XAFS experiments were measured using a fluorescence method. XAFS scans covering the Co K edge peak were taken during the first charge/discharge reactions.

Figure 1 shows the XRD patterns of the multilayer all-solid-state battery during the first cycle in the charge/discharge process. The main diffraction peaks of LCPO are located at around 13.0°, 14.4°, and 16.7°. The diffraction peak position at 16.7° gradually shifts to the lower degree side from its uncharged state and the peak intensity decreases during the charging process. In addition, the peak shift returns to the same position at the uncharged state during the discharging process. However, that is not completely. The diffraction peak intensity at 14.4° decreases. In the XAFS measurement results, the Co K edge spectrum shifts to the higher energy side compared to the uncharged state during the charging process. The Co K edge spectrum returns to the same energy position in the uncharged state during the discharging process. These results show that the valence of Co changes from 2+ to 3+ upon charging and returns from 3+ to 2+ upon discharging. We observed how the Co of the LCPO operates while the multilayer all-solid-state battery was charging and discharging.

[1] A. Kato, The 395th Committee Of Battery Technology, (2019)

[2] M. Kobayashi, et al., The 60th Battery Symposium, 2F19, (2019)

[3] C. Yamamoto, et al., The 87th ECSJ Spring Meeting, (2020)

Figure 1