bluuebunny/crossref_metadata_2025 huggingface dataset:
Porous Silica as a Nanotemplate for the Solid State and Liquid Phase Synthesis of Luminescent Carbon Dots
Authors: Vasin A. V. , Kysil D. V. , Sevostianov S. V. , Isaieva O. , Rudko G. Yu. , Yatskiv Roman , El Hamzaoui H. , Capoen B. , Bouazaoui M. , Tertykh V. , Nazarov A. N.
Published: May 2020

Samples of nanoporous silicon oxide (pore size of 40 nm and 6 nm with specific are of 90 m2/g and 233 m2/g respectively) were synthesised by sol-gel method and used as nanotemplate for solid stated and liquid phase synthesis of lluminescent carbon nanodots (nanoagregates). Solid state method was two step process of chemical treatment of porous silicas by toluene solution of phenylstrimethoxisilane followed by pyrolysis at temperature in range of 400-600 0C for 60-180 minutes. Three characteristic emission bands in UV and VIS spectral range (360-380 nm, 410-420 nm, 440-450 nm) and their combinations were found in annealed por-SiO2:C depending on annealing time and temperature. The nature of light emission of pyrolytic carbon moieties in SiO2:C nanopowder was analysed and discussed in frame of the concepts of polycyclic carbon clusters and their aggregates based on the analogy with polycyclic organic molecules and luminescent carbon nanodots. It is suggested to assign the characteristic emission bands at about 380 nm and 420 nm to polycyclic carbon fluorophores with 2- and 3-ring structure respectively. The other low energy characteristic emission bands at wavelength 440-450 nm and higher are assigned to amorphous nanoaggregates. It is found that PL intensity of por-SiO2:C nanocomposite is sensitive to the absorption of the air. Response of the PL on absorption/desorption of air moieties was studied and discussed.

Hydrophylic carbon nanodots were synthesized by liquid phase thermolysis of sucrose in dimethyl sulfoxide solution at 200 0C that resulted in formation of luminescent colloid. Porous silica were infiltrated by this colloid and then dried. Luminescent moieties absorbed in porous silicas were then extracted in water resulting in aqueous solution that exhibited intense visible photoluminescence with maximum intensity at 430-440 nm and well pronounced excitation band at 360-400 nm. This emission is suggested to be assigned to hydrophilic amorphous carbon nanodots (nanoagregates). Examination of Z-parameter of the colloids gave a value of the size of carbonnanodots below 1 nm. Spectral parameters (maximum position and spectral width) of the emission and excitation of photoluminescence were found to be dependent on the size of the pores in porous silica template that can be assigned to the effect of the size and size distribution of carbon nanodots (nanoagregates).

As a summary, it was shown that nanoporous silica with high specific surface area can be used as solid state “container” for both solid state and liquid phase synthesis of carbon nanoemitters with emission spectrum variable from the near UV to the visible.
Surface Engineering of Cesium Lead Halide Perovskite Nanocrystals for Enhanced Air Stability
Authors: Lim Sung Nam , Kim Kiyoung , Song Shin Ae , Woo Ju Young
Published: May 2020

Cesium lead halide perovskite nanocrystals (CsPbX3 NCs where X is Cl, Br, and I) have become of great interest to numerous researchers because CsPbX3 NCs exhibit highly bright photoluminescence (PL), very narrow full width at half maxima (FWHM) of PL spectra. Also, recently demonstrated soft and dynamic nature of crystal domain in CsPbX3 NCs triggered fundamental interests. However, very unfortunately, it has been known that CsPbX3 NCs are too much unstable under air environment. For instance, PL quantum yield shows drastic drop when the NCs are stored in air conditions. Also, NCs fuse together along [110] crystal direction which finally results in degradation of their initial properties. Therefore, preventing degradation of CsPbX3 NCs in air is the most crucial issue for wider deployment of CsPbX3 NCs.

Here, we report surface ligand transition from anionic oleate ligands to cationic oleylammonium ligand on the surface of CsPbX3 NCs. Addition of ZnX2 enables such surface ligand transition of NCs. Furthermore, exposure of fusion-vulnerable (110) facets is markedly inhibited when the surface is terminated with cationic oleylammonium ligands, possibly due to significant difference in formation energy of (100) and (110) facets.
Synthesis of Alkyl-Substituted Viologen Cation/Indanyl Anion Organic Charge Transfer Salts
Authors: Saito Erika , Yasuhara Taichi , Okada Shuji , Yamakado Ryohei , Matsui Jun , Katagiri Hiroshi , Fujiwara Wataru , Masuhara Akito , White Matthew , Headrick Randall , Yoshida Tsukasa
Published: May 2020

Combination of ionic organic donor and acceptor to form crystalline salt can be an interesting strategy to obtain new types of organic semiconductors, since charge transfer (CT) excitonic properties are anticipated. We have previously achieved a novel CT salt from deprotonated 1,3-(bisdicyanomethylidene)indan anion (TCNIH-) and methyl viologen cation (MV2+) in a 2:1 composition. In this study, the n-alkyl chain length in viologen was systematically changed to find out the border for the evolution of CT character of the mixed salts. [1]

Propyl to hexyl viologens (PrV to HxV) were synthesized by quaternization of 4,4’-bipyridine using the corresponding 1-haloalkanes in the yields of 60-62%, whereas methyl, ethyl, heptyl and octyl viologens (MV, EV, HpV, OV) were commercially available. Co-crystals with TCNIH- were precipitated by mixing with viologens at 2 : 1 ratio in water, filtrated and recrystallized from ethanolic solutions. While their crystal structures were examined on powder samples and single crystals, their optical properties were studied by measuring UV-vis and photoluminescence (PL) spectra for CT excitation.

Co-crystals with TCNIH- were obtained for all viologens in a 2:1 ratio in the yields of 39-44%. While Na+ salt with TCNIH- preserves the character of the deprotonated TCNIH- in solution, showing a peak at around 590 nm and its absorption extending up to around 850 nm, those with RV2+ having short alkyl chains exhibit absorption towards NIR range and concomitant decrease of visible absorption, due to CT from TCNIH- to RV2+ (Fig. 1). A clear border can be found between PnV and HxV, as the CT absorption is significantly decreased when R is longer than Hx.

Crystal structures of the mixed salts were identified as monoclinic for MV, BV, HxV salts, while triclinic for the others. The powder XRD data as well as melting points determined by differential scanning calorimetry indicated significant enlargement of donor-acceptor distances, decrease of melting point, and thereby weakened interaction to account for the observed CT characters. Coulombic interaction between donor and acceptor result in close packing of these co-crystals for their CT characters, whereas it is hindered when alkyl chains longer than Hx is introduced. However, PL from CT states was observed for all the compounds, as the salts with HxV, HpV and OV also showed clearly longer emission than that of Na salt, indicating primary excitation confined in TCNIH-, followed by its relaxation down to the CT states in such salts.

Reference

[1] E. Saito, et al., ECS Trans., 2018, 88, 301-311

Figure 1
(Invited) Biodegradable Light-Emitting Organic Materials
Authors: Santato Clara
Published: May 2020

(Opto)electronics is one of our most developed and pervasive technologies.

The enduring high demand for (opto)electronics and their energy powering components has led to massive amounts of Waste of Electrical & Electronic Equipment (WEEE).

We will discuss our research efforts on the integration of solution-processable electro- and photo-active organic electronic nanomaterials available from biomass feedstock into (opto)electronic and energy technologies, such as light-emitting transistors and batteries, to minimize their environmental footprint.

We will include in our discussion preliminary results on the biodegradability of such photo-active nanomaterials.
Carbon Free Si Electrode Based on Micron Size Si Particles for Advanced Lithium Ion Rechargeable Battery
Authors: Liu Gao
Published: May 2020

Silicon (Si) is an attractive candidate for lithium-ion batteries because it delivers 10 times greater theoretical (∼4200 mAh/g) specific capacity than that of a traditional graphite anode (∼370 mAh/g). However, the widespread application of silicon materials has remained a significant challenge because of the large volume changes during lithium insertion and extraction processes, particularly when using bulk or micrometer-sized silicon particles. This large volume change causes cracking and pulverization of silicon, which leads to loss of the electrical contact and drastic capacity fading. To address the significant challenges associated with large volume change of micrometer-sized Si particles as high-capacity anode materials for lithium-ion batteries, we demonstrated a simple but effective strategy: using Si nanoparticles as a structural and conductive additive, with micrometer-sized Si as the main lithium-ion storage material. The Si nanoparticles connected into the network structure in situ during the charge process, to provide electronic connectivity and structure stability for the electrode. The resulting electrode showed a high specific capacity of 2500 mAh/g after 30 cycles with high initial Coulombic efficiency (73%) and good rate performance during electrochemical lithiation and delithiation: between 0.01 and 1 V vs Li/Li+.
Investigation of Li+ Insertion in NMC622 Cathode Material upon Deep Lithiation Via Electrochemistry and x-Ray Absorption Spectroscopy
Authors: Usubelli Camille , Besli Muenir Mustafa , Kuppan Saravanan , Metzger Michael , Christensen Jake , Gorlin Yelena
Published: May 2020

Nickel-based cathode materials have become an exciting alternative to the widely used LixCoO2 (LCO) for consumer electronics. The main advantages of this type of cathode materials over the LCO electrodes are a higher practical capacity and excellent safety characteristics.[1] Additionally, the tendency to increase the nickel content of these electrodes proves to be cost effective due to their lower cobalt content.[2] One known drawback of nickel-containing layered cathodes is their poor first cycle efficiency of 87-88.6% when cycled in the standard potential window of 2.8 V to 4.4V, whereas LCO cathodes reach a first cycle efficiency of 98%.[3]

In this study, we focus on the electrochemical properties of LixNi0.6Mn0.2Co0.2O2 (NMC622) cathode materials. We start by demonstrating that it is possible to recover the capacity “lost” by the NMC622 electrode in the first cycle by increasing the applied overpotential, as was previously shown for other nickel-based cathodes, including LiNiO2, LiNi1/3Mn1/3Co1/3O2, and LiNi0.8Co0.10Al0.05O2.[3-4] We then establish through electrochemical measurements that it is possible to overlithiate the NMC622 cathode material by as much as 300 mAh/g relative to the pristine electrode. Finally, we complement our electrochemical characterization with ex-situ X-ray diffraction as well as soft and hard X-ray absorption spectroscopy experiments, to elucidate how the structure of the material and the oxidation states of the transition metals (nickel, cobalt, manganese) change throughout the overlithiation process.

[1] Andre, D. et al. Future generations of cathode materials: An automotive industry perspective. J. Mater. Chem. A
3, 6709–6732 (2015).

[2] Xu, J., Lin, F., Doeff, M. M. & Tong, W. A review of Ni-based layered oxides for rechargeable Li-ion batteries. J. Mater. Chem. A
5, 874–901 (2017).

[3] Kang, S. H., Yoon, W. S., Nam, K. W., Yang, X. Q. & Abraham, D. P. Investigating the first-cycle irreversibility of lithium metal oxide cathodes for Li batteries. J. Mater. Sci.
43, 4701–4706 (2008).

[4] Dahn, J. R., von Sacken, U. & Michal, C. A. Structure and electrochemistry of Li1+/-xNiOz and a new Li2Ni02 phase with the Ni (OH) 2 structure. Solid State Ionics
44, 87–97 (1990).
Solid-State NMR and Electrochemical Dilatometry Study of Charge Storage in Supercapacitor with Redox Ionic Liquid Electrolyte
Authors: Wang Yanyu , Rochefort Dominic
Published: May 2020

Redox ionic liquids are emerging as promising new electrolytes for supercapacitors, which provide higher capacitance and energy density than organic or ionic liquid electrolytes. The fundamental studies of charge storage mechanism in supercapacitors are of critical importance for the development and applications of devices. Solid-state NMR (SS-NMR) methodology that has the ability to give atomic information on local environments within electrodes has been recently developed to study the mechanism of charge storage in supercapacitors at molecular level. The charge storage in supercapacitors with organic or ionic liquid electrolytes has been studied by SS-NMR. However, there is until now no research on supercapacitors with redox-active electrolyte published. Therefore, the study of charge storage mechanism in supercapacitors with redox-active electrolyte are highly required. In this context, we employed SS-NMR techniques combined with electrochemical dilatometry measurements that are associated with charge induced strain of electrode to investigate in depth the charge storage during charging process in supercapacitors with redox ionic liquid electrolyte. It is revealed that the charging process of supercapacitors with redox ionic liquid electrolyte EMIM FcNTf/ACN is driven by different charge regimes for different voltages, that is, co-ion desorption at low voltage range and subsequently counter-ion adsorption at higher voltage range. The electrochemical dilatometry measurements show macroscopic change of the electrode during charging and further confirm the proposed mechanism obtained from SS-NMR. The results give a detailed picture of the charging mechanism of supercapacitors with redox ionic liquid electrolyte, providing new insights on the charge storage of supercapacitors.
Synthesis of Colloidal Nitrogen-Doped Graphene Quantum Dots with Tunable Bandgaps Using Atmospheric Pressure Microplasmas
Authors: Kurniawan Darwin , Chiang Wei-Hung
Published: May 2020

Graphene quantum dots (GQDs) have obtained a great of research interest owing to their unique material properties including tunable bandgaps, biocompatibility, chemical and photo-stability, controlled functionalization, and low toxicity, making then promising candidate for applications including bioimaging, chemical and biological sensing, drug delivery, energy conversion and storage, catalysis, and optoelectronics. However, the low quantum yield (QY) and difficulty to synthesize have hampered the commercialization of GQDs. Nitrogen (N) doping of GQDs has been shown as an effective approach to enhance the QY and further change the materials properties. It is needed to develop a scalable, controlled and environmental-friendly method to synthesize N-doping GQDs (NGQDs).

Here we demonstrate a simple microplasma-based approach for NGQD synthesis. Recently, microplasma has attracted a lot of attentions due to its advantages for nanomaterials synthesis. Chitosan was used as the raw carbon and nitrogen sources for producing NGQDs. Three different acids including HCl, HNO3, and CH3COOH were used to mix with the precursors. Generation of energetic species including radicals and electrons were found to initiate electrochemical reactions and simultaneously nucleate nano-size graphene and growth of NGQDs. Microscopic and spectroscopic studies suggest NGQD with controlled particle size, N dopant concentrations and bandgaps can be achieved by adjusting the process conditions. Our work provides a simple, scalable and green method for synthesis of GQD with well-defined structures.
(Invited) Microplasma: A New Technology Platform for Nanomaterials Synthesis and Applications
Authors: Chiang Wei-Hung
Published: May 2020

Microplasmas are a special class of electrical discharges formed in geometries where at least one dimension is less than 1 mm. As a result of their unique scaling, microplasmas operate stably at atmospheric pressure and contain large concentrations of energetic electrons (1-10 eV). These properties are attractive for a range of nanomaterials synthesis including metal and semiconductor nanoparticles, nanocarbons, and metal/semiconductor heteronanostrutures. Recently, we found that the energetic species including radicals, ions and electrons generated in the microplasmas were capable of initiating electrochemical-assisted reactions for the nucleation and growth of nanographenes. Moreover we develop a simple synthesis of silver (Ag) nanoparticles (NPs)/nanographene nanoheterostructures using a unique atmospheric-pressure microplasma-assisted electrochemical method. The systematic micro Raman study indicates that the synthesized AgNP/nanographene composites process superior plasmonic properties. In this presentation, I will discuss these topics in detail, highlighting the advantages of microplasma-based systems for the synthesis of well-defined nanographenes and nanoheterostrutures. These experiments will aid in the rational design and fabrication of nanomaterials and may also have significant impact in emerging applications.
Effect of Plasma-Activated Zinc Oxide Surface on Liquid Stability
Authors: Stražar Petra , Zavašnik Janez , Likozar Blaž , Cvelbar Uros
Published: May 2020

The ZnO is an essential material in material science, agriculture, food industry, cosmetics, medicine etc. Most applications exploit ZnO physicochemical properties such as optical, electrical, mechanical and thermal. In material science, ZnO is commonly used in gas sensors, light-emitting diodes, field-effect transistors, UV lasers, photodetectors, solar cells, photo and heterogeneous catalysis. The ZnO characteristics for different applications can be controlled by size and morphology of particles with numerous techniques.

In this work, we study the effect of UV light and plasma treatment on ZnO surface morphology, crystallography and effect on its other intrinsic properties. For study, the UV-A/C light is used and compared to atmospheric pressure plasma generated in Ar or He as well as low-pressure RF – ICP plasma generated in oxygen gas. The research is focused on how UV or other plasma related changes influence the material intrinsic properties and change stability of liquid organic compounds in low ppm concentrations. The resulting interaction between stable liquid and modified material namely result in creation of other unstable molecules and compounds as well as reactive species. This approach enables improved design of catalytic performance of nanomaterials by designing their surface properties by plasma, beyond mere enhancement of surface area. The targeted liquids for modifications are thiophens in organic solvents, where we need to look at interactions of this liquids with material. To unravel these interactions, various analyses are used including UV-Vis, HPLC, and NMR. Further for surface characterisation of materials, the analyses including XPS, FTIR, UV-Vis, BET, SEM and TEM are used. The obtained results give then systematic explanation, how UV or plasma changes of material intrinsic properties translate into targeted liquid interactions and modifications.
(Invited) Nitrogen Fixation Using Non Thermal Atmospheric Plasma (over water): Challenges and Perspectives on Nitrogen Fixation Using Non Thermal Atmospheric Plasma (over water): Challenges and Perspectives
Authors: Maira Nicolas , Remy Antoine , Roy Nepal Chandra , Pattyn Cédric , Reniers François
Published: May 2020

Nitrogen fixation, i.e. the transformation of molecular nitrogen into nitrates or ammonia is a major industrial process. The Haber-Bosch and the Ostwald processes are at the origin of the massive increase of yield of food production, contributing to the development of modern agriculture. However, despite the fact that these processes are exothermic, the need to operate at high temperature for kinetic reasons, the necessity to start (most often) from natural gas as a source of hydrogen, and the industrial plants located far away from the end user, make these industrial processes huge producers of CO2.

Historically, the Birkeland-Eyde process, however, allow to fix nitrogen using arc plasma. The energy yield of this process being small, it was replaced by the Haber-Bosch process. With the development of low temperature, non thermal plasmas processes, there is nowadays a hope to develop local, low energy cost, nitrogen fixation reactors, with only air as reactant. For food and agriculture applications, especially for urban agriculture, a possible approach is to generate nitrates directly inside the water that feeds the plants. The talk will present a few non thermal atmospheric plasma setups than can be used for nitrogen fixation. In a first setup, nitrogen oxides are generated directly in a dielectric barrier discharge (DBD) filled with various proportions of nitrogen and oxygen. In a second setup, one of the dielectrics is replaced by water. In a third setup, a DC microplasma is lighted up between a metallic electrode and a water solution, containing an electrolyte. In this last setup, a counter electrode closes the electrical circuit, making it resembling a electrochemical cell. In this last setup, two configurations are tested, by changing the polarity of the two electrodes.

For all the setups, the amount of various nitrogen oxides formed in the gas phase as a function of the experimental parameters is studied using optical emission spectrometry, infrared spectrometry and mass spectrometry. Similarly, the composition of the liquid phase is analyzed using ionic chromatography and specific reagents tests. Correlations between a) the gas phase composition and b) the liquid phase composition are established. The role of OH radicals (in the gas phase) and hydrogen peroxide (in the liquid phase) on the relative amounts of nitrites and nitrates is evidenced. For the microplasma experiments, it is shown that inverting the polarity of the electrodes lead to drastic changes in the yields of the species produced. From all these results, potential mechanisms will be presented, and future challenges will be open to discussion.
Sustainable Closed-Loop Recycling of Spent Solid Electrolytes and Electrodes in All Solid-State Batteries
Authors: Tan Darren Huan Shen , Yang Hedi , Xu Panpan , Nguyen Han , Wu Erik , Banerjee Abhik , Doux Jean-Marie , Wang Xuefeng , Meng Shirley , Chen Zheng
Published: May 2020

With rapidly increased lithium ion batteries (LIBs) adoption, the need for sustainable battery recycling is a matter of utmost importance. Spent LIBs contain lithium, cobalt, nickel and other transition metals that are not only economically valuable but are also limited in terms of their geographical availabilities. Conventional recycling technologies, such as pyrometallurgy and hydrometallurgy, tend to be energy intensive, costly, and use toxic chemical processing which can be difficult to handle. Additionally, materials recovery efficiency remains low, due to low recycling rates of other components in the cell such as the liquid electrolyte and lithium salts. This is primarily because today’s LIBs are not designed specifically for recycling ease. While it might be too late for conventional batteries, next generation all solid-state batteries (ASSBs) might instead stand a chance. In this work, we developed a sustainable and practical ASSB recycling model, that involves complete closed-loop recyclability of all components in the cell including the solid electrolyte and electrodes. We demonstrate efficient separation and recovery of the solid electrolyte and spent electrodes from a cycled lithium metal full cell, without using toxic chemicals or energetic processes. These recovered materials are directly regenerated into their original usable formats without any breakdown of their core chemical structure. The fully recycled materials are then used to fabricate new ASSBs, achieving the same performance level as pristine ASSBs. This study provides a promising opportunity for sustainable recovery and recycling of spent ASSBs.
Lithium Intercalation Layer Eliminate Dendrite to Achieve Stable Long-Life Lithium-Sulfur Battery
Authors: Chu Chih-Wei , Jou Shyankay , Kaisar Nahid
Published: May 2020

High energy density battery technology for portable electronics and grid energy system are in high demand. Lithium anode considered as the suitable electrode for commercialization of lithium-ion battery because of having highest specific capacity, lowest reduction potential and low density. However, uncontrolled lithium dendrite growth results in low coulombic efficiency, internal short-circuit of the cells. Here, we demonstrate δ-CsPbI3 as a protective layer for lithium metal anode fabricated by a low-cost, facile spray coating methodology. Furthermore, experimental and density function theory study confirms the lithium ion intercalate in the crystal structure of δ-CsPbI3. Lithium intercalation into δ-CsPbI3 fast the lithium ion migration, stabilize the electrodeposition and maintain the integrity of SEI layer. We observe a dendrite free plating for 1000 hours at a current density of 1 mA cm-2 and discharge capacity of 1 mAh cm-2. We achieve a starting discharge capacity of 823 mAh g-1 and coulombic efficiency of ⁓100% throughout 1000 cycles with decay rate of ⁓0.035% per cycle in a Li-Sulfur full cell configuration. Our new concept accomplish a stable lithium metal for future commercialization and open up new area of research to achieve safe lithium anode.
Effect of Cation Substitution on the Sodium Ionic Conductivity of Nasicon-Type Solid Electrolyte
Authors: Yang Chun-Chi , Chen Han-Yi
Published: May 2020

The invention of secondary batteries technology is a milestone in the electronic industry. However, the liquid organic electrolytes suffer from safety issues such as flammability and explosion. This give rise to the progress of new solid electrolytes as non-flammable alternatives. Another obstacle that prevents all-solid-state electrolytes from practical use is the high contact resistance between electrode and electrolyte which results in low ionic conductivity. Therefore, our study aims to develop a chemically stable sodium solid electrolyte with high ionic conductivity at room temperature.

In this study, we modified a NAISCON-type sodium ionic solid electrolyte by cation substitution. By using NASICON/polymer film, we reduced the contact resistance between electrolyte and electrodes. The modified materials were analyzed by scanning electron microscopy, X-ray diffraction analysis, and electrochemical impedance spectroscopy measurements. An ionic conductivity up to 10-4 S cm-1 at room temperature was obtained. The modified NASICON-type sodium ionic solid electrolyte was then assembled into a full-cell system to demonstrate its applications in all-solid-state sodium ion batteries.

Keywords: solid electrolytes, polymer film
Very High Lithium Diffusion in LiTi2(PS4)3 through Energy Landscape Frustration
Authors: Hautier Geoffroy , Di Stefano Davide , Miglio Anna , Robeyns Koen , Filinchuk Yaroslav , Lechartier Marine , Senyshyn Anatolyi , Ishida Hiroyuki , Spannenberger Stefan , Roling Bernard , Prutsch Denise , Rettenwander Daniel , Wilkening Martin , Kato Yuki
Published: May 2020

Solid-state materials with fast high ionic diffusion are necessary to many technologies including all-solid-state Li-ion batteries.

Here, we demonstrate that LiTi2(PS4)3 (LTPS) exhibits the largest Li-ion diffusion coefficient ever measured in a solid. We use extensive characterisation (neutron, X-ray diffraction, impedance and NMR) as well as theoretical studies to study the lithium diffusion in LTPS. We show for instance with recent X-ray data that the Li mobility is so high that low temperature is needed to freeze and observe the lithium ions positions. We rationalise the exceptional performances of this new superionic conductor through the concept of frustrated energy landscape. The absence of regular and undistorted lithium site to occupy leads to low energy barrier for diffusion as well as an exceptional pre-factor. We discuss how this frustration could be present in previously known ionic conductors and be used to search and design new structural families of superionic conductors.
Safe Electrolytes for Li-Ion Batteries
Authors: Wang Chunsheng
Published: May 2020

Li-ion batteries are the critical enabling technology for the portable devices, electric vehicles (EV), and renewable energy. However, the safety and energy density of current Li-ion batteries still need to be improved to satisfy the requirements for these applications. We systematically investigated the electrochemical performance of the nonflammable fluoridated organic electrolytes, water-in-salt electrolytes and solid state electrolytes for high energy Li and Li-ion batteries. The critical issues of these safe electrolytes are also discussed
(Invited) Templated Electrodeposition By Molecular Assemblies: Exploring Limits
Authors: Yao Zhen , Buehl Michael , Buck Manfred
Published: May 2020

Organic molecules play a vital role in deposition processes, both as randomly adsorbed entities to control kinetics and as organized layers in area selective deposition. Applications of the latter include deposition from the gas phase such as atomic layer deposition as well as from solution in processes ranging from electrochemical and electroless deposition of patterned metal films to the growth of layers of metal-organic frameworks. While self-assembled monolayers (SAMs) offer a convenient way to templated deposition down to the scale of tens of nanometers, the move towards the bottom end of the nanoscale poses increasingly stringent requirements on their structure and properties. This encompasses both the precision at which SAM patterns can be defined and the extent to which these layers can direct nucleation and control growth.

As far as electrodeposition is concerned, SAMs have been employed to generate metal patterns by harnessing their versatility and modifying a combination of interfacial properties such as adhesion and charge transfer. Typically, chemically passive molecules are used and the process is based on defects present in a SAM. Thus limiting resolution due to the statistical distribution of defects as regards their size and location, a complementary strategy where the deposition process can be actively controlled by a molecular property seems more promising to advance templated electrodeposition to the ultrasmall length scale. A scheme which affords such an active control is based on functionalized SAMs. As illustrated in the cartoon, metal ions are coordinated at the outer interface of the SAM (step 1) and reduced in a subsequent electrochemical step (2). Yielding deposits on top of the SAM, these can act as seeds for the deposition from the bulk electrolyte (3), thereby enabling the generation of ultrathin layers and the combination of different metals. Due to weak adhesion between the deposit and the SAM, structures can be lifted off and transferred to other substrates, thus offering a replicate generation of patterns.

The presentation addresses issues which are key to achieving ultrahigh resolution. Strategies aimed at overcoming current limitations as regards variability in dimensions are discussed, arguably one of the most pressing problems in the move towards ever smaller features. This involves topics ranging from the factors controlling coordination chemistry of SAMs to their design beyond single component systems.

Figure 1
(Invited) In-Situ Microscopy and Spectroscopy Probing of Li Dendrite Nucleation and Growth
Authors: Wang Chongmin
Published: May 2020

Lithium (Li) metal has very low standard electrochemical redox potential and very high theoretical specific capacity, making it an ultimate anode material for rechargeable batteries. However, its application has been impeded by the formation of Li whiskers, which not only considerably consumes electrolyte and active Li, but also may lead to short-circuit of the battery. Tackling of these obstacles is limited by the elusive understanding on the intrinsic formation mechanisms of the Li whiskers and their growth behavior under the constraints from the separator. Here, by coupling an atomic force microscopy cantilever into a solid open-cell setup in environmental transmission electron microscopy, we directly captured the nucleation and growth behavior of Li whiskers under elastic constraint that mimics the effect of a separator. We show that Li deposition is initiated by a sluggish nucleation of a single crystalline Li particle with no preferential growth directions. Dramatically, we discovered that carbonate species in the initial solid electrolyte interphase that is very adjacent to the developing Li metal plays a decisive role in the subsequent formation of Li with a whisker morphology. Characteristically, the growing Li whisker, depending on both intrinsic and extrinsic conditions, can yield, buckle, kink, or stop (axial) growth under elastic constraint from the separator. These findings reveal the intrinsic cause and give a clear process on the formation and behavior of dendritic Li under stress, providing the much-needed insights for solving the Li whisker formation from the root cause rather than as currently containing it, and therefore potentially leading to the safe operation of Li metal anode in batteries.
HE3DA Lithium Battery 3-D Technology - Essential Element for Smart Grid
Authors: Prochazka Jan , Zukalova Marketa
Published: May 2020

Large energy storage applications require ultimate safety, economical manufacturing and full recyclability of the batteries. HE3DA lithium battery technology platform with 3-D electrode architecture meet all these demands. The cell construction increases battery safety by orders of magnitude. For the first time, lithium batteries allow to build the most reliable, safe, recyclable, compact and economical energy storage units. Main features of this technology and cell parameters produced in a freshly opened Gigafactory will be discussed.
Porous Electrode Phase Transition Kinetics in Li-Ion Batteries
Authors: Campos Juan Alfonso , Deva Abhas , Lund Jarrod , Jana Aniruddha , Battiato Ilenia , García R. Edwin
Published: May 2020

Traditional Porous Electrode Theory has provided an impressive amount of insight on the description of the intercalation kinetics of rechargeable batteries by describing the porous electrochemically active electrode as a diffusion and ohmic system with a spatial distribution of reversible interfacial reactions. Here, events such as phase transformations are fit into a curve by using the open circuit potential (OCP), and mass and interfacial reactions are described by starting from the classic reaction theory and fitted to experimental data. Recent experimental results highlight that the kinetics associated to phase transformations occurring during the intercalation/deintercalation process, are key to specifying battery performance and long term degradation. These kinetics, however, are theoretically and numerically complex to spatially resolve at a level that would make them practical to use in commercial applications. In this paper, we report on progress in the formulation of a coarse grained description that naturally accounts for the volumetric electrochemical phase transformations and reactions in a porous rechargeable batteries by starting from fundamental materials science principles. The effect of stresses in the intercalation kinetics is incorporated by upscaling the free energy-based phase field representations of the constituent materials is being developed. Comparisons against available experimental data are presented.
Design for Hydrogen Electrochemical Engine (HECE)
Authors: Park Jong-Hee
Published: May 2020

Author would like to introduce the novel design on hydrogen electrochemical engine (HECE);based on the current Electrochemical Energy Technology (ECT) system will be reviewed to find out the key development to the most effective pursuing way. The basic concept and engineering design for the HECE that is the combining fuel cell and thermal to electric converter which is the only unique in the hydrogen energy technology system. Presentation will be covered on the issue that introducing HECE will have the highest hydrogen fuel energy efficiency with having uniqueness to further development in the Electrochemical Energy Technology (ECT). We have known well on Fuel Cells and its benefit, problems, and further need. Since 1990's designing combined heat and power (CHP) has been required for upgrading electrochemical energy conversions. Author has found the Hydrogen has an uniqueness to design a thermal to electrical converter, (TEC), from the fuel cell generating heat can be utilized and adding to the electrical power as, HECE = HFC + HTEC. As we have known TEC semiconductors based p-n coupling, and AMTEC have its limit to the low efficiency, finding p-n couple to applying, and optimal operation temperatures for ambient environment. Presentation will be described on its energy efficiency with the details on design on HECE.
Directly Generated Hydrogen to Feed a 2.4 Kw PEM Fuel Cell Stack By Hydrolysis of Nanoporous Aluminum with Pure Water
Authors: van der Pluijm Martijn W.G. , Chen Randy , Lee Asaph , Mui Jonathan , Corsi John S , De Hosson Jeff T.M. , Detsi Eric
Published: May 2020

Jules Verne stated more than 145 years ago that water will be the coal of the future [1]. Indeed, hydrogen, a highly abundant substance on Earth in the form of water, is a promising energy carrier for producing zero-emission electricity upon reaction with oxygen using fuel cell technology. There are still many scientiﬁc and engineering challenges that need to be addressed before Jules Verne’s dream can become true, however. Two of these challenges include hydrogen production from water and hydrogen storage. In this talk, I will present our work on direct hydrogen generation by hydrolysis of nanoporous aluminum in pure water to feed a 2.4 kW PEM fuel cell stack, which in turn can be used to power a low speed electric vehicle. The possibility to make nanoporous aluminum from secondary aluminum and the advent of carbon-free primary aluminum from Elysis [2,3] could make hydrogen production by hydrolysis of aluminum with pure water a promising alternative to hydrogen production by electrolysis of water.

References:

[1] Ryabchuk, V. K., Kuznetsov, V. N., Emeline, A. V., Artem’ev, Y. M., Kataeva, G. V., Horikoshi, S., & Serpone, N. (2016). Waterwill be the coal of the future-the untamed dream of Jules Verne for a solar fuel. Molecules, 21(12), 1–20. https://doi.org/10.3390/molecules21121638

[2] Corsi, J. S., Fu, J., Wang, Z., Lee, T., Ng, A. K., & Detsi, E. (2019). Hierarchical Bulk Nanoporous Aluminum for On-Site Generation of Hydrogen by Hydrolysis in Pure Water and Combustion of Solid Fuels. ACS Sustainable Chemistry and Engineering, 7, 11194–11204. https://doi.org/10.1021/acssuschemeng.9b00481

[3] ELYSIS. Retrieved from https://www.alcoa.com/global/en/what-we-do/elysis/.
Quantifying Nucleation Rates in Phase-Transforming Metal-Ion Intercalation Materials Based on Cyclic Voltammetry and Chronoamperometry Data
Authors: Nikitina Victoria A
Published: May 2020

Phase-transforming cathode materials with a wide miscibility gap have been extensively studied for both Li-ion (LiFePO4, Li4Ti5O12) and Na-ion (Na3V2(PO4)3) batteries. In particular, LiFePO4 material has become a model system for the investigation of intercalation induced phase transformation mechanisms.1 Most of the state-of-the-art research on the phase-separating intercalation materials focuses on the elucidation of phase transformation mechanisms as well as on the theoretical assessment of the nucleation barrier heights based on the evidence from structural investigation and microscopic single particle-level experiments.2

In this work, we show that the new phase nucleation appears to be a characteristic rate-determining step for a wide range of intercalation materials (LiFePO4, V2O5, cation-rich Prussian blue analogues, Na3V2(PO4)3). We demonstrate that the nucleation rates (probabilities of critical nucleus formation) can be straightforwardly determined from the electrochemical experimental data. A simple experimental approach is proposed based on the classical nucleation theory toward interpreting electrochemical cyclic voltammetry and chronoamperometry data for phase-transforming electrodes.3 The new methodology provides for a facile assessment of the influence of various experimental factors (particle size, defect concentration, solvent nature, and surface coating) on the nucleation-controlled phase-transformation rates in intercalation materials.4 Experimental data analysis illustrates the validity of the applied approaches, which allows developing diagnostic criteria for distinguishing slow nucleation rate control from other possible rate-determining steps as well as obtaining quantitative estimates of the nucleation rate constants.

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1. Malik, R.; Abdellahi, A.; Ceder, G. J. Electrochem. Soc. 2013, 160, A3179.

2. Bai, P.; Bazant, M. Z. Nat. Commun. 2014,
5, 3585.

3. Vassiliev, S.Yu.; Levin, E.E; Presnov, D.E; Nikitina, V.A. J. Electrochem. Soc. 2019, 166, A829.

4. Iarchuk, A.R.; Nikitina, V.A.; Karpushkin, E.A.; Sergeyev, V.G.; Antipov, E.V.; Stevenson, K.J.; Abakumov, A.M. ChemElectroChem 2019, 6, 5090.

Figure 1
High Temperature Electrolysis: Combining Metal Extraction and Energy Storage?
Authors: Allanore Antoine , Rush Lucas
Published: May 2020

The promise of deploying green electric power faces the challenge of intermittency and integration within existing infrastructure. Meanwhile the global demand for metals, whether from primary or recycled sources, is steadily growing. The processes of the latter sector are not currently able to utilize a surge in inexpensive, clean electricity while being a large energy consumer (of the scale of 20 to 100MW). A window of opportunity exists where metal processing technologies can be re-designed to act as an electricity consumer or producer, depending on the electricity market conditions. In this work, we analyze and discuss conditions in which high temperature electrolysis techniques can fulfill this role.
Palladium Electrodeposition from Deep Eutectic Solvents
Authors: Soma Fousséni , Baustert Christophe , Rayée Quentin , Bougouma Moussa , Doneux Thomas , Buess-Herman Claudine
Published: May 2020

Palladium is a platinum group metal that has been reported to be useful as electrocatalyst for several important reactions such as formic acid oxidation, alcohol oxidation and oxygen reduction. In this context the electrodeposition of Pd is of particular interest.

Palladium electrodeposition in aqueous media requires potentials close to the decomposition of water, leading to low faradaic yields and embrittlement of electrodeposited palladium. The use of unconventional solvents such as deep eutectic solvents (DESs) is expending as a promising alternative for the electrochemical deposition of metals. These are obtained by mixing a quaternary ammonium salt and a hydrogen-bond donor, leading to a melting point much lower than the pure components. These eutectics are easy to prepare, inexpensive and offer a high electrical conductivity. Owing to their thermal stability and wide electrochemical window, these media become more widespread in the field of metal electrodeposition, though fundamental studies are relatively scarce.

The present work focuses on the electrodeposition of palladium from deep eutectic solvents based on choline chloride.

The electrochemical behaviour of Pd(II) has been investigated at 60°C in choline chloride–urea (ChCl-U) and choline chloride–oxalic acid (ChCl-Ox). Cyclic voltammetry (CV) and potentiostatic measurements performed in the presence of Pd(II) at a glassy carbon electrode (GC) are compared with data obtained at a gold electrode.

Peaks in the CV curves are assigned to the Pd deposition and its dissolution but also to the formation of palladium hydride (PdHx). The Pd(II) electrochemistry is significantly different in the two DESs, owing to their differing proton donating properties and Pd speciation.

By selecting appropriate potentials, Pd electrodeposits were formed and analysed. The kinetics of Pd electrodeposition was followed by chronoamperometry. The i-t curves obtained at a glassy carbon electrode clearly revealed that the metal deposition is controlled by a nucleation and growth process. The current transients, discussed on the basis of existing models, indicate that the deposition occurs via 3D nucleation with diffusion controlled growth.
Initial Stage of Si Electrodeposition Process in Ionic Liquids
Authors: Homma Takayuki , Tsuyuki Yasuhiro , Kunimoto Masahiro , Fukunaka Yasuhiro , Pianetta Piero A.
Published: May 2020

Si thin films are key material for electronic/energy devices such as photovoltaic cells and battery electrodes, as well as various MEMS devices. For their fabrication process, electrochemical approaches attract attention featuring high productivity and precise controllability to form micro/nano structures to wide surfaces. Since Si has very negative redox potential, non-aqueous electrolytes with molten salts, ionic liquids (ILs), or organic solvents are required. We have applied the ILs such as trimethylhexyl ammonium (TMHA+) bis-trifluorosulfonyl imide (TFSI-) and investigated their deposition process focusing upon the initial stage. The analysis using electrochemical quartz crystal microbalance (EQCM) [1] suggested that the reaction of the source of Si in the electrolyte, SiCl4, proceeded via Si (III) and Si(II) intermediate species. From the results of X-ray reflection (XRR) analysis and density functional theory calculation [2], it was indicated that the SiCl4 species adsorped onto the surface initially formed multimer, and this “precursor” was subsequently transformed into Si layers.

The authors would like to thank Dr. J. Komadina, Mr. M. Nishida, and Mr. T. Fujimura for their experimental help and valuable discussion. This study was financially supported in part by the Japan Science and Technology Agency (JST) CREST program.

[1] Y. Tsuyuki, A. Pham, J. Komadina, Y. Fukunaka, T. Homma, Electrochim. Acta, 183, 49 (2015).

[2] Y. Tsuyuki, T. Fujimura, M. Kunimoto, Y. Fukunaka, P. Pianetta, T. Homma, J. Electrochem. Soc., 164, D994 (2017).
Electrodeposition for Oxygen Evolution and CO2 Reduction
Authors: Gewirth Andrew A. , Chen Xinyi S. , Henckel Danielle A.
Published: May 2020

This talk addresses the use of electrodeposition to make catalysts for oxygen evolution and CO2 reduction. We show that N-containing ligands which are effective to make good ORR catalysts also have a positive role in other chemistries, particularly those involving CO2 reduction and the oxygen evolution reaction. By specifically tailoring electrodeposition conditions, electrodes exhibiting very high activities can be fabricated. We show that the introduction of a few weight percent of an alloy into the base catalyst can dramatically change the electrocatalytic properties of the material. Spectroscopic methods are utilized to provide an explanation of the effect.