bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Lithium Ion Battery Combining a Sustainable CuO-Carbon Conversion Anode with a High Voltage Li0.85Ni0.46Cu0.1Mn1.49O4 cathode
Authors: Verrelli Roberta , Scrosati Bruno , Hassoun Jusef
Published: February 2020

The development of novel cell configurations represents a key step towards a lithium ion batteries technology able to meet the increasing global energy demand.

The search for sustainable and low cost electrode materials exhibiting high specific capacity, efficiency and stability is a longstanding goal of electrochemistry(1).

In this respect, the replacement of conventional intercalation anodes with transition metal oxides reacting by conversion mechanisms is a promising, cheap approach to increase the cell specific capacity(2). Furthermore, the exploitation of cobalt-free, manganese spinel-structure materials at the cathode side is expected to overcome the problems deriving from the high cost and relatively low operating voltage of the presently most used LiCoO2 electrodes.

Here we propose an alternative lithium ion battery combining an easily prepared, eco-compatible CuO-MCMB (Meso Carbon Micro Beads) conversion anode(3) (Theoretical capacity:  520 mAh g-1) with a high voltage, Li0.85Ni0.46Cu0.1Mn1.49O4 spinel-structure cathode(4) (Theoretical capacity: 146 mAh g-1), using propylene carbonate (PC), LiPF6 electrolyte solution.

Both the anode, prepared by high energy ball milling, and the cathode, obtained by co-precipitation and solid state reaction, exhibit optimized morphologies that lead to good electrochemical responses in terms of stability, efficiency and rate-capability. The electrodes structures and morphologies are analyzed by X-ray diffraction and scanning electron microscopy, respectively, while their electrochemical behaviors in cell are investigated by means of potentiodinamic cycling with galvanostatic acceleration (PCGA) and galvanostatic cycling tests at different C-rates.

The novel electrode combination here disclosed results in a full lithium ion battery characterized by an operating voltage of 3.4 V, a stable capacity of 90 mA h g-1 and a coulombic efficiency higher than 95% (see Figure below), with estimated gravimetric and volumetric energy densities of about 100 Wh/kg and 220 Wh/l, respectively.

The rationale of this cell configuration lies in the employment of sustainable, low-cost and easily prepared electrode materials that make the battery particularly suitable for practical exploitation.

(1) D. Larcher, J-M. Tarascon, Nature Chemistry, 2015, 7, 19.

(2) J. Cabana, L. Monconduit, D. Larcher and M. Palacìn, Advanced Materials, 2001, 22, E170.

(3) R. Verrelli, J. Hassoun, A. Farkas, T. Jacob, B.Scrosati, Journal of Material Chemistry A, 2013,1, 15329.

(4) R. Verrelli, B. Scrosati, Y.-K. Sun, J. Hassoun, ACS Applied Materials & Interfaces, 2014, 6, 5206.

Figure 1
Fire-Retardant Pyrrolinium-Based Ionic Liquids As Electrolytes for Lithium Ion Batteries
Authors: Kim Hyung-Tae , Yim Taeeun , Mun Junyoung , Oh Seung M. , Kim Young Gyu
Published: February 2020

Lithium ion batteries (LIBs) have some advantages such as a high energy density, negligible memory effect and a less self-discharge. Consequently, they have been applied to not only small electronic devices but also large energy storage systems. Although LIBs have been considered as one the most promising energy conversion/storage systems, the safety issue of LIBs must be overcome to realize large, high-power, and high-voltage LIBs. To get over the limitation of safety, many kinds of approach have been attempted to enhance the safety of the LIBs and one of the efficient ways is partial or total replacement of combustible organic electrolytes with a new class viscous materials, acting as poorly flammable and/or flame retardant components. In this respect, ionic liquids (ILs) have been considered as attractive electrolyte candidates because they are non-flammable owing to its unique chemical nature.

 The ILs are salts that remain as liquid at room temperature even if they are composed of ionic species, cations and anions. Due to the ionic nature in bonding, ILs show favorable physicochemical properties such as high ionic conductivity, non-volatility, and non-flammability as well as a wide liquid range and wide electrochemical stability window. Previously reported imidazolium-based ILs with low viscosity and high ionic conductivity have some defects such as decomposition of an acidic proton at the C-2 position[1]. To overcome the decomposition imidazolium ring, we have studied saturated cyclic ammonium-based ILs based on pyrrolidinium[2] or piperidinium[2], which showed more stable electrochemical behavior compared to the imidazolium-based ILs, but less favored physicochemical properties such as high viscosity and lower ionic conductivity.

 In this work, some novel pyrrolinium-based ionic liquids have been prepared and studied as electrolytes for LIBs to address those problems. Introduction of a beneficial functional group such as an oxygen atom into the partially saturated pyrrolinium ring was expected to give some positive effects on both the electrochemical stability and the physicochemical properties. Therefore, several target ILs that were synthesized in the present study showed higher thermal stability than the combustible organic solvent such carbonates. We will present the thermal, physicochemical, and electrochemical properties of several pyrrolinium-based ionic liquids as electrolytes, which are compared to those of the conventional carbonate.

[1] Bull. Korean Chem. Soc., 2006, 27, 847

[2] Bull. Korean Chem. Soc.,
2007, 28, 1567

Figure 1
Graphdiyne for High Capacity and Long-Life Lithium Storage
Authors: Huang Changshui , Zhang Shengliang , LI Yulliang
Published: February 2020

We explored bulk GDY powder as an anode material in practical LIBs to evaluate its Li storage properties. GDY powder with microporous and mesoporous structure can be prepared easily according to the cross-coupling reaction and processed to anodes of any shape. The LIBs assembled with GDY-based anodes exhibit high specific capacity, excellent rate performance as well as long cycle life. Those results indicate that GDY is an efficient material for Li storage and has the potential to be applied in energy storage applications.
Electrochemical Stability of PEDOT:PSS As Cathodic Binder for Li-Ion Batteries
Authors: Das Pratik Ranjan , Komsiyska Lidiya , Osters Oliver , Wittstock Gunther
Published: February 2020

Cathodes in Li-ion batteries are composites and consist of redox active compounds such as metal oxides (LiCoO2, LiMn2O4, LiNixMnyCozO2) or metal phosphates (LiFePO4), and electrochemically inactive components with different functionalities. Organic polymers such as polyvinylidene difluoride (PVDF) are used as binder that forms a supporting matrix for the active material particles (1, 2). The properties of the binder significantly influence the electronic/ionic conductivity and the mechanical properties of the electrodes and the battery behavior (3). Since the commonly used binders are electrically insulating, additives such as carbon black and carbon nanotubes are added to the electrodes. However, the addition of redox inactive compounds reduces the total electrode capacity and has a crucial influence on the battery performance and stability.

          In our recent work we proposed a new electrode concept for LiFePO4 cathodes, where poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) plays a dual role of binder and conducting additive (4). The new composite cathodes were prepared free of any other conductive additives such as carbon black or carbon nanotubes. The results show that an increasing PEDOT:PSS content leads to a decrease in the overvoltage and correspondingly to an improvement in the rate capability of resulting electrodes.

          In this contribution we report the electrochemical behavior of PEDOT:PSS casted on an Al current collector in an aprotic Li-containing electrolyte in the potential range 2.5 to 4.2 V. In addition, the influence of the temperature on the electrochemical performance of the polymer was examined in the temperature range 10 °C to 50 °C by cyclic voltammetry and electrochemical impedance spectroscopy. The obtained results show, that the polymer is electrochemically inactive in the applied potential window and remains in the oxidized conductive state. The polymer film shows high electrochemical stability and only slight changes in the impedance are visible during multiple cycling.

Reference

1. I. Krylova, Prog. Org. Coat., 42, 119 (2001).

2. S. Babinec, H. Tang, A. Talik, S. Hughes, G. Meyers, J. Power Sources, 174, 508 (2007).

3. B. Lestriez, C. R. Chim, 13, 1341 (2010).

4. P. R. Das, L. Komsiyska, O. Osters, G. Wittstock, J. Electrochem. Soc 162 (4) 674 (2015).
Tin Sulfide(SnS) 3-D Nanoflowers with Superb Kinetic Property for the Anodic Use in Next-Generation Sodium Rechargeable Battery
Authors: Cho Eunbi , Song Kyeongse , Park Mihui , Agyeman Daniel Adjei , Kang Yong-Mook
Published: February 2020

The ever-increasing demands of high power/energy density battery for electric vehicles (EVs) and hybrid electric vehicles (HEVs) as well as large-scale energy storage systems (ESSs) bring about the development of next-generation rechargeable battery systems with price competitiveness. Lithium rechargeable battery has been considered as a promising candidate for energy storage because of its high energy density. Unfortunately, the utilization of lithium rechargeable battery for large scale applications is restricted due to limited lithium resources leading to high cost. On the other hand, sodium metals and sodium compounds indeed have merits in terms of cost and suitable redox potential of Na ions (Na/Na+= 2.71 V vs. SHE at 298 K, 1 M, 1 atm), which can facilitate to commercialize sodium rechargeable battery for large scale application. Even if sodium rechargeable battery has recently attracted considerable interest, it still has low efficiency and poor cycle life at present. Such drawbacks are mainly attributed to the large ionic radius of Na ion (35% larger than Li ion), which may prompt mechanical stress and poor Na ion diffusivity in active materials of both cathode and anode sides. Therefore, there have been many attempts to design well-tailored materials for sodium rechargeable battery. Among them, metal sulfides have been extensively studied due to their fundamental properties for important technological applications. In particular, SnS has attracted much attention recently due to high theoretical capacity of 1,022 mAh/g, which is attributed to conversion and alloying-dealloying reaction with Na ion.

Here, we devised SnS three-dimensional (3-D) nanoflowers containing hierarchically organized two-dimensional (2-D) nanosheet subunits. Based on the electrochemical observations, SnS 3-D nanoflowers revealed that the unique morphology with large surface area and electrochemical interfacial region facilitates highly efficient Na ion insertion and extraction compared to those of bulk counterparts. Futhermore, the ex-situ characterizations let us know that the space between the each individual 2-D nanosheet subunit can effectively accommodates volume changes during charge/discharge process. Thus, the SnS 3-D nanoflowers can be considered as one of the most promising anode materials with superb kinetic property and stable cycle performance for sodium rechargeable battery.
Vacancy Ordering in Layered Metal Oxide Na-Ion Battery Cathodes
Authors: Toumar Alexandra J. , Ong Shyue Ping , Richards William Davidson , Dacek Stephen , Ceder Gerbrand
Published: February 2020

Current state of the art Na-ion battery cathodes are selected from the broad chemical space of layered first row transition metal (TM) oxides. Unlike their lithium ion counterparts, seven first row layered TM oxides can intercalate Na ions reversibly. Their voltage curves also indicate significant and numerous reversible phase transformations during electrochemical cycling. These transformations are not yet fully understood, but arise from Na-ion vacancy ordering and metal oxide slab glide.

In this study, we investigate the nature of vacancy ordering transformations within the O3 lattice framework. We generate predicted electrochemical voltage curves for each of the Na-ion intercalating layered single TM oxides using a high-throughput framework of density functional theory (DFT) calculations. We determine a set of vacancy ordered phases appearing as ground states in seven O3-NaxMO2systems (M = Ti, V, Cr, Mn, Fe, Co, Ni) and investigate the effect on phase stability of ordering interactions between adjacent sodium layers.

References

S. P. Ong, V. L. Chevrier, G. Hautier, A. Jain, C. Moore, S. Kim, X. Ma, G. Ceder. ”Voltage, stability and diffusion barrier differences between sodium-ion and lithium- ion intercalation materials” Energy Environ. Sci. (2011) doi:10.1039/c1ee01782a

C. Didier, M. Guignard, C. Denage, O. Szajwaj, S. Ito, I. Saadoune, J. Darriet, C. Delmas. ”Electrochemical Na-deintercalation from NaVO2” Electrochem. Solid St. 14, 5, A75-A78 (2011) doi:10.1149/1.3555102
Towards a Better Understanding of Aprotic Alkali-Oxygen Batteries
Authors: Nazar Linda F , Kundu Dipan , Xia Chun , Black Robert , Adams Brian , Fernandes Russel
Published: February 2020

In the search for high density electrochemical energy storage, non-aqueous rechargeable metal-O2 batteries are very attractive owing to their reliance on molecular oxygen, which forms oxides on discharge that release oxygen reversibly on charge. Much work has focused on aprotic Li–O2 cells, but the aprotic Na-O2 system is of equal interest owing to its more reversible chemistry.  In both cells, a chemically stable and conductive cathode interface is prerequisite for sustainable cell operation, along with a non-aqueous electrolyte that minimizes parasitic reactions at the electrode/electrolyte interface.  Li-O2 cells (unlike their sodium counterparts), are also characterized by a high charge overpotential that must be overcome in order to increase round-trip efficiency.  In the last year, much progress has been made towards achieving these goals owing to a better understanding of the cell chemistries.   This presentation will focus on those topics, covering developments from our lab that include non-carbonaceous cathode hosts that possess stable conductive interfaces for reduced polarization on O2 evolution, and novel soluble oxidation catalysts capable of Li2O2 oxidation without direct electrical contact with the cathode.  Characterization techniques ranging from electron microscopy, surface spectroscopy and operando electrochemical mass spectrometry have been applied to investigate the viability of various proposed systems.  This has resulted a deeper understanding of the critical parameters for positive electrodes in aprotic A-O2 batteries, which will be presented in this talk.
Investigation of the Graphene Supported Platinum-Tungsten Catalysts Prepared By Microwave Synthesis As Electrocatalysts for Borohydride Oxidation
Authors: Kilmonis Teofilius , Tamasauskaite-Tamasiunaite Loreta , Balciunaite Aldona , Vaiciuniene Jurate , Norkus Eugenijus
Published: February 2020

In the study presented herein a rapid microwave heating method was used to prepare the graphene supported platinum-tungsten catalysts (denoted as Pt-W/GR) with the different Pt:W molar ratios. The prepared catalysts were characterized by means of Transmission Electron Microscopy, X-ray diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy. The electrocatalytic properties of the Pt-W/GR catalysts towards the oxidation of borohydride in an alkaline medium were investigated by means of cyclic voltammetry and chrono-techniques.

It was found that the graphene supported platinum-tungsten catalysts with the Pt:W molar ratios equal to 1.6:1, 2.4:7 and 7.1:1 were prepared by microwave-assisted heating of Pt(IV) and W(VI) salts in ethylene glycol solutions.

It has been determined that the synthesized Pt-W/GR catalysts with the different Pt:W molar ratios show an enhanced electrocatalytic activity towards the oxidation of H2 generated by catalytic hydrolysis of BH4
– and direct oxidation of BH4
– comparing with the graphene supported bare W catalyst. The Pt-W/GR catalyst having the Pt:W molar ratio equal to 7.1:1 exhibits the highest electrocatalytic activity for the both oxidation reactions of H2 and BH4
– ions as compared with that at the Pt-W/GR catalysts with the Pt:W molar ratios equal to 1.6:1 and 2.4:1.
Investigations on Oxygen Evolution Catalysts for PEM Electrolysis Cells
Authors: Waltar Kay Erik , Fabbri Emiliana , Schmidt Thomas J.
Published: February 2020

In recent years, electricity-driven hydrogen production by electrochemical splitting of water (water electrolysis) has received particular attention because of its potential applicability in decentralized energy storage concepts.  The electrolysis of water is nowadays mainly performed in alkaline or acidic electrolytes.  The acidic polymer electrolyte electrolysis cell (PEEC) has distinct advantages over the alkaline liquid electrolyte devices. PEECs can rapidly respond to changes in the power input and operate at a larger partial load range. Furthermore, high voltage efficiencies and the possibility to be operated at high pressures > 100 bar favor its use. Nevertheless, the anodic oxygen evolution reaction (OER) is catalytically demanding, showing high overpotentials. Additionally, the strongly oxidizing environment reduces the set of applicable materials to a few noble transition metal (mixed-) oxides. Transition metal oxides based on ruthenium and iridium constitute the state of the art catalysts for the OER performing with high catalytic activity and sufficient stability1. The low availability of iridium raises its costs and new catalyst materials and/or surface morphologies have to be investigated to either replace or reduce the iridium content. For this purpose, a promising strategy is to develop catalyst materials as mixed oxides with non-noble substitutes and a high surface area. These new materials need to be characterized with respect to their performance and stability. Especially, at the high potentials which are needed to drive the oxygen evolution reaction, a thermodynamic instability of the catalysts lattice oxide anions may lead to an oxygen evolution from the lattice and concomitantly to an electrochemical corrosion of the material. Rotating ring-disc electrodes (RRDEs) enable the estimation of generated oxygen and thereby the determination of the catalysts current efficiency. Within this study the RRDE method will be applied to several promising OER catalysts to determine their current efficiencies. In addition, the materials stability with respect to its application in electrolysis cells facing intermittent power input will be investigated. 

Financial support of this project by CCEM (RENERG2), the Commission for Technology and Innovation (CTI) and the Swiss Competence Center for Energy Research (SCCER) Heat & Electricity Storage is gratefully acknowledged.

1.            Fabbri, E.; Habereder, A.; Waltar, K.; Kötz, R.; Schmidt, T. J., Developments and perspectives of oxide-based catalysts for the oxygen evolution reaction. Catalysis Science & Technology 
2014, 4 (11), 3800-3821.

2.            Kötz, R.; Stucki, S., Stabilization of RuO2 by IrO2 for anodic oxygen evolution in acid media. Electrochimica acta
1986, 31 (10), 1311-1316.
New Direct Alcohol and Hydrogen Fuel Cells for Naval and Aeronautical Applications (PILCONAER)
Authors: Mosa Jadra , del Rio Carmen , Morales Enrique , Raso Miguel A. , Leo Teresa J. , Maellas Jesús , Aparicio Mario , Moreno Berta , Chinarro Eva
Published: February 2020

In the current context of demand for reliable, low cost and low environmental impact energy sources, many countries and companies are mostly focused on fuel cells (FC) in fields as transportation and stationary power generation and portable devices. Lately, FCs have begun to be applied in naval and aeronautical systems due to its high efficiency, low noise and environmental advantages. These applications could range from propulsion systems to auxiliary power units (APU). The main problems associated with the use of FCs in these areas are the current high cost due to the materials used, i.e. Nafion and Pt, the lack of durability testing in these specific conditions, security issues to flammability and high H2
pressures and low availability as a fuel, or the toxicity of methanol used as a fuel, and specific parameters such as weight in aircraft applications and volume in marine applications. Currently it is working on each of these issues, and at this point the ethanol as direct fuel is considered crucial. The use of ethanol as fuel has the advantage of easy transportation, storage and refueling, and is nontoxic. Bioethanol is a promising energy source, produced from raw materials containing sugar or starch. These raw materials exists in all parts of the world and is renewable, which involves the use of local energy sources contributing to the diversification of energy supply, reducing import dependence, increasing security of supply and generating new opportunities for agriculture.

The main objective of the proposal is the development of low power stacks (stacks) fed with methanol (DMFC) and ethanol (DEFC) based on the development of new catalysts and membranes. The materials are considered first from the point of view of application in FCs fed with H2 (PEMFC) to be optimized and used on FCs fed directly with alcohols. An important particular objective is the development of cells fed with ethanol in alkaline medium in order to eliminate the use of Pt as the catalyst and increase the efficiency of the electrochemical FC while cost is decreased. The proposed development of new FCs fed with alcohols, especially ethanol, is considered a technology of sustainable use, further commitment to the restoration of the natural environment and biodiversity conservation.

The consortium combines groups: skilled in synthesis and characterization of materials (CSIC); expert in the development and evaluation of FC stacks (UPM and INTA) and with the ability to develop physical and mathematical models to predict the behavior of the fuel cell equipped for the MEAs fabricated (UCM). Four companies have shown interest in the proposal, as well as participation according to preliminary results.
Comments on the Problem of Metal Ions Crossing through the Cations Membrane Electrolyte in Electrolysers and Redox Flow Cells
Authors: Reda Mahmoud R.
Published: February 2020

Redox flow Cells and hydrogen produced electrolysers are important green source of energy of the future. These cells can be activated to store energy (redox flow cells) and produce CO free hydrogen (electrolysers) by solar, wind or sea wave’s energy. In this Redox flow batteries and electrolysers a cations exchange membrane (e.g. Nafion from Du Point a cations exchange membrane selective to cations only) is used to separate the anodic regions from the cathodic regions. It is observed experimentally that during operations of these cells metal ions crosses from one region of the cell to the other which greatly lowers the efficiency of the process (irreversible capacity loss). This problem was partially solved in the case of Fe (II)/Fe(III) and Cr(II)/Cr(III) redox flow battery by utilizing the condition of electro-neutrality[1,2].The idea of mixed electrolyte introduced by Hagedorn [1] from NASA is based is using mixed cations in both anodic and cathodic regions so that during operation of the Fe (II)/Fe(III) and Cr(II)/Cr(III) redox flow cells the cations get reduced or oxidized instead of crossing the membrane and the condition of electro-neutrality is satisfied. The purpose of this publication is to generalize the application of the condition of electro-neutrality to other redox flow batteries and electrolysers and to give simple mathematical modeling of this effect [3].

 [1] Introduction of mixed reactants, elevated temperatures and additive electrocatalysts NASA TM-83401.

[2] Gahn, R. ; Hagedorn, N.; and Ling, J. S.: Single Cell Performance Studies on the Fe/Cr Redox Energy Storage System Using Mixed Reactant Solutions at Elevated Temperature. Proceedings of the Eighteenth Intersociety Energy Conversion Engineering Conference, AIChE, 1983, pp. 1647-1652.

[3] Rakib et al., Journal of Applied Electrochemistry 29: 1439, 1999.
Fuel Cell Diagnostics through Neutron Imaging
Authors: Boillat Pierre , Oberholzer Pierre , Biesdorf Johannes , Schmidt Thomas J.
Published: February 2020

The operation of polymer electrolyte fuel cells (PEFC) at high current density is of high importance in order to minimize the total stack area – an in consequence the system cost – for a given output power. At high current density, mass transport losses can become an important limitation, in particular in relation with the accumulation of water in the fuel cell porous layers. In this context, the visualization of liquid water in operating fuel cells has been extensively applied (e.g. (1-7)) in the last decade. Among the different visualization methods available, neutron imaging features the unique combination of being non-invasive (due to the transparency of fuel cell materials and the absence of radiation damage to the cell) and providing an excellent contrast for liquid water. However, unravelling the relation between water accumulation and mass transport losses cannot be done without combining visualization with advanced electrochemical characterization methods.

In a first part, the recent advances at PSI in neutron imaging and combined diagnostics methods will be presented. The advantages and limitations of mass transport characterization methods such as electrochemical impedance spectroscopy (EIS), limiting current density and our recently developed pulsed gas analysis (PGA) (5) will be presented. Additionally, the choice of test cell hardware and its impact on results from these methods will be discussed.

In a second part, a selection of experimental results will show how the combination of imaging and advanced electrochemical characterization can bring a new understanding to the mass transport limiting processes. A particular attention will be given to the choice of gas diffusion layer (GDL) material characteristics such as the amount of hydrophobic coating and the presence of a microporous layer (MPL).

1.            R. Satija, D. L. Jacobson, M. Arif and S. A. Werner, J Power Sources 129, 238 (2004).

2.            J. P. Owejan, J. J. Gagliardo, J. M. Sergi, S. G. Kandlikar and T. A. Trabold, Int J Hydrogen Energ, 34 3436 (2009).

3.            D. Kramer, J. B. Zhang, R. Shimoi, E. Lehmann, A. Wokaun, K. Shinohara and G. G. Scherer, Electrochim Acta 50, 2603 (2005).

4.            A. B. Geiger, A. Tsukada, E. Lehmann, P. Vontobel, A. Wokaun and G. G. Scherer, Fuel Cells 2, 92 (2003).

5.            P. Boillat, P. Oberholzer, A. Kaestner, R. Siegrist, E. H. Lehmann, G. G. Scherer and A. Wokaun, J Electrochemical Soc 159, F210 (2012).

6.            P. Oberholzer, P. Boillat, R. Siegrist, R. Perego, A. Kastner, E. Lehmann, G. G. Scherer and A. Wokaun, J Electrochemical Soc 159, B235 (2012).

7.            J. Biesdorf, P. Oberholzer, F. Bernauer, A. Kaestner, P. Vontobel, E. H. Lehmann, T. J. Schmidt and P. Boillat, Phys Rev Lett 112, 248301 (2014).

Figure caption:

Figure 1 – Top: Neutron radiograms of a differential fuel cell operating at 1 A/cm2 with different humidities. Bottom: corresponding transport losses measured using our PGA method. Reproduced from ref. (5).

Figure 1
Production of Hydrogen and Chemicals from the Electroreforming of Renewable Alcohols
Authors: Miller Hamish Andrew , Vizza Francesco , Bevilacqua Manuela , Lavacchi Alessandro , Bellini Marco , Chen Yanxin , Wang Lianqin
Published: February 2020

The exploitation of hydrogen in fuel cells is widely advocated as the ideal solution for an energetically and environmentally sustainable future for transportation. An essential part of such a solution will be the use of renewable energy resources (photovoltaics, wind, wave power etc.) in conjunction with water electrolysis to provide a “zero emission” source of hydrogen. Water electrolysis is a well-established commercial technology; nevertheless its practical application for the mass production of hydrogen is still limited mainly due to costly electrical energy consumption.

Both Alkaline and PEM electrolyzers exploit water splitting, evolving hydrogen at the cathode and oxygen at the anode. The standard reaction potential for this process is 1.23 V, meaning that water splitting is a strongly uphill reaction. In practice to get current densities in the range of 1 A cm-2 the cell potential usually ranges between 1.6 and 2 V. Considering 1.8 V as a reasonable average, we conclude that 68.3% of the energy input is consumed by thermodynamics, while kinetic factors account for only 31.7%.

Replacing anodic oxygen evolution with the oxidation of much more readily oxidizable species leads to a significant reduction of the potential required to produce hydrogen. Following this strategy compounds such as ammonia, methanol, ethanol, glycerol and urea have been tested. These electrolytic processes that lead also to the concomitant generation of chemicals at the anode and hydrogen at the cathode are often indicated as “Electrochemical Reforming”.

While undoubtedly promising, these approaches suffer the limitation of delivering current densities well below 1 A cm-2, and as such are unpractical for technological exploitation. Here we propose to overcome such limitations using a range of nanostructured anode electrocatalysts which combine fast electrode kinetics for alcohol electrooxidation with tunable selectivity for the formation of partially oxidised intermediates of industrial interest. We demonstrate that electrochemical reforming can occur at current densities comparable to that of state of the art PEM water electrolysis. Furthermore we report a net energy analysis of hydrogen production by bio-ethanol electrochemical reforming. Particularly, we define the energy cost break-even point, expressed in terms of the Energy Return of the Invested Energy of bio-ethanol production, at which electrochemical reforming becomes more energy efficient than water electrolysis.
Advanced RuO2/PEDOT Architecture for Flexible and Transparent Supercapacitors
Authors: Zhang Chuanfang , Higgins Thomas , Coleman Jonathan N , Nicolosi Valeria
Published: February 2020

The ever-increasing development of smart electronics requires powerful energy storage devices, in particular supercapacitors with flexible and transparent properties. Increasing the mass loading of active material promotes the specific capacity (or capacitance) at the expense of transparency and flexibility of the supercapacitor electrodes. Therefore in order to maintain high transmittance, thin films which constitute of pseudocapacitive material and conductive network would be highly desirable. Here we report on a RuO2/PEDOT hybrid thin film by a simple aerosol-jet spray technique. It was found that RuO2 loading and electrode thickness have great effects on the transmittance and sheet resistance of the thin film, which could be well explained and fitted via the percolation theory.1,2 By loading 40 wt.% RuO2, the hybrid thin film demonstrated a transmittance of 94%, a lowest sheet resistance and a highest areal capacitance (1.4 mF cm-2) among other hybrid films. The solid-state symmetric supercapacitor was assembled, which demonstrated fast-rate response and retained 100% of initial capacitance after 10000 cycles. When pairing up the hybrid thin film positive electrode with the PEDOT thin film negative electrode, the solid-state asymmetric supercapacitors exhibited a voltage window of 1.2 V and a transmittance of 84%. Furthermore, thin films with large area (100 cm2) was also sprayed and assembled into asymmetric solid-state supercapacitor, demonstrating its scalability.
Modelling of Proton Density Distribution in Active Nanopores of Fuel Cell Catalyst Layers
Authors: Muzaffar Tasleem Ahmad , Eikerling Michael
Published: February 2020

Proton density and mobility in porous electrodes determine the proton conductivity as well as the rates of interfacial electrochemical processes. In the case of polymer electrolyte fuel cells (PEFCs), the foremost practical objective is to design porous electrodes or catalyst layers with high performance at markedly reduced platinum loading. Achieving this objective demands an understanding of the impact of composition and porous structure as well as surface structure and charging properties of pore walls on the proton density distribution
1
. In the presented work, we consider simple pore geometries to study the concerted effects of ionomer structure and metal charging properties on proton density in nanopores. The approach employs Poisson-Nernst-Planck theory
2, 3
. The basic model system is a cylindrical pore confined by an ionomer shell. The core to consist of a solid metal rod and the gap space between the core and the ionomer shell is filled with water. The set of ordinary differential equations for proton density and reaction in these model structures is formulated and solved. Solutions are analysed by comparing potential and proton density distributions for varying pore geometries and charging properties at interfaces. The effectiveness factor of catalyst utilization is calculated to evaluate the electrocatalytic performance at the pore level
4, 5
.

 References

[1] A.Weber et al., J. Electrochem. Soc. 161(12), (2014), F1254-F1299

[2] R.Coalson and M.Kurnikova, Biological membrane Ion channels, Chap 13, Springer, NewYork (2001)

[3] K.Chan and M.Eikerling, J. Electrochem. Soc. 158(1), (2011), B18-B28.

[4] K.Chan and M.Eikerling, J. Electrochem. Soc. 159(2), (2012), B155-B164

[5] A.Bonnefont, F.Argoul, and M.Z.Bazant, J. Electroanal. Chem., 500, 52, (2011
Understanding the Limitations of Solid-State Lithium Batteries for Electric Vehicles
Authors: Ji Yan , Srinivasan Venkat
Published: February 2020

The market penetration of electric vehicles is hindered by their safety issues and limited driving range, due to the intrinsic instability of liquid electrolytes as well as the low capacity of insertion materials used in lithium-ion technology. Solid electrolyte, including solid polymer electrolyte, inorganic solid electrolyte as well as hybrid electrolytes, provide a solution to these barriers owing to the promise of better safety and the compatibility with Li metal (higher energy density).

In the past several decades, tremendous efforts have been made to increase the ionic conductivity of the solid electrolytes. However, it is still not clear if the properties of presently available solid electrolytes are sufficient to meet the targets for electric vehicle batteries. Therefore, there is a need to correlate the electrolyte properties at the material level to battery targets at the cell and system level.

In this study, we present a material-to-cell level analysis of solid electrolytes. Continuum electrochemical models are used to project energy and power capabilities of solid-state cells based on their material properties. The models use appropriate material properties, where available, and compared to experimental data to ensure validity.  The validated model is then used to estimate the cell-level energy and power capability following the testing protocols targeting electric vehicles application. This analysis helps to identify existing challenges and provides guidelines for research at both material and cell levels for this promising class of next-generation batteries.
Systematic Analysis on Ionic Conductivity of LiBH4 Infiltrated into Mesoporous Scaffolds
Authors: Choi Yong Seok , Oh Kyu Hwan , Cho Young Whan , Lee Young-Su
Published: February 2020

It has been known that LiBH4 has a hexagonal crystal structure with a high ionic conductivity (~ 10-3 S/cm) above ~ 110 ℃, although it undergoes a reversible phase transformation to an orthorhombic crystal structure with a low ionic conductivity (~ 10-8 S/cm) below the phase transition temperature. So, many researchers attempted to extend the stability region of the high temperature phase up to room temperature by making a solid solution of LiBH4 and lithium halides. Another route to increase the ionic conductivity of LiBH4 is nanoconfinement. The confinement of LiBH4 in the mesoporous scaffolds amorphizes the structure raising the ionic conductivity as high as ~ 10-4 S/cm even at room temperature. However, it is still unclear which mechanism, i.e. nanoconfinement or generation of interface between LiBH4 and SiO2, governs the ionic conductivity enhancement of infiltrated LiBH4.

We therefore systematically investigate the ionic conductivity of LiBH4 and a mesoporous silica (here MCM-41) composite system. In order to separate the effect coming from nanoconfinement and interface, as-purchased MCM-41 was hand-mixed with LiBH4 in one case while in the other case mesopores of MCM-41 was intentionally destroyed by high-energy ball-milling. Interestingly, ionic conductivity of ball milled LiBH4 – MCM-41 mixture turned out to be ~ 10-5 S/cm, which is smaller than that of LiBH4 infiltrated into MCM-41 but it is 1000 times higher than that of pure LiBH4. The result highlights the importance of interface effect and indicates that significant enhancement in ionic conductivity can be achieved through interface engineering. To further exploit the interface effect, volume fraction of LiBH4 was systematically varied, and other kinds of compounds were tested. We believe that such approach can be useful for designing a fast ionic conductor for lithium ion battery.
Supercapacitive Properties of Composite Electrodes Consisting of Activated Carbon and 1,4-Dihydroxynaphthalene Derivative
Authors: Latifatu Mohammed , Park Jeong Ho , Yoon Choong Sup , Ko Jang Myoun
Published: February 2020

Two 1,4-dihydoxynaphthalene (PhQH2)-based derivatives (coded as HBU-551 and HBU-552) are synthesized by reacting with different amines (i.e., tryptamine and phenethylamine, respectively) to use as organic additives of activated carbon supercapacitors. The composite electrodes with HBU-551 and HBU-552 are also prepared by blending with the ratio of 70:25 w/w, and their supercapacitive properties are investigated in terms of redox behaviors and specific capacitance evolutions against scan rate and cycle life. The organic additives and their composites with activated carbon are dominantly characterized by PhQ-PhQH2 redox transition accompanying a two-electron two-proton process, and weakly affected by reversible redox reaction of nitrogen in the -NH group, which involves an additional one-electron one-proton process. Thus, the composite electrodes show higher specific capacitance over 210 F g-1 due to the synergistic effect between activated carbon (pseudocapacitance) and organic additives (redox behavior). Cycle performance and high-rate capability can also be enhanced by the adoption of PhQH2-based organic additives for their pore-filling morphology to increase the packing density of composite electrodes.
Micro-Raman Characterization of Single Particles for Phase Transformations Study in Lithium Titanate
Authors: Slautin Boris N. , Gorshkov Vadim S. , Kuznetsov Dmitrii K. , Zelenovskiy Pavel S. , Alikin Denis O. , Kiselyov Eugene A. , Kholkin Andrei L. , Shur Vladimir Ya. , Pelegov Dmitry V.
Published: February 2020

Fast growth of battery market driven by electric vehicle (EV) and stationary energy storage system (ESS) segments has stimulated interest for lithium titanate Li4Ti5O12 (LTO) with its low cost, perfect cycleability and excellent safety. Whereas low electric conductivity (10-8 ÷ 10–13S/cm) is a weak point of LTO, it can be compensated by the grain size reducing down to sub-micron even nano scales. In spite of modern level of nanotechnology development, the structural characterization is still mainly made by non-local methods. In this work we demonstrate that structural heterogeneity in commercial negative electrode material LTO with sub-micron grain size synthesized using standard solid-state method can be described not only thermodynamically, but also locally in terms of structural characterization of single particles using standard micro-Raman Spectroscopy together with Scanning Electron Microscopy.

Solid state synthesis of Li4Ti5O12 was made using chemically pure titanium dioxide TiO2 (anatase) and chemically pure lithium carbonate Li2CO3by the following reaction:

2Li2CO3 + 5TiO2 = Li4Ti5O12 + 2CO2↑                                                                      (1)

Our modification of usual solid-state method, based both on analysis of intermediate reactions and review of the published data, uses three consequent synthesis stages with intermediate grinding which increased influence surface layers on material physical properties. In order to simplify other phases observation we knowingly increased the content of phase diagram nearest compositions TiO2 и Li2TO3by using partial (incomplete) synthesis with skipped third stage.

Raman spectra of single particle (Figure 1) clearly demonstrate heterogeneity of phase transformations during reaction (1) and allow making us some conclusions about the processes peculiarities which can’t be made otherwise.

Figure 1: SEM images and corresponding Raman spectra of single particles of (b) final phase Li4Ti5O12 and two nearest phases: (a) Li2TiO3 and (c) TiO2 rutile. SEM images sizes are 0.8×1.0 µm.

Figure 1
High Performance Fuel Cell Membrane By Electric Poling of Poly (ether sulfone)/Sulfonated Poly(ether ether ketone) Composite
Authors: Fang Yu-shin , Chu Peter Po-jen
Published: February 2020

Traditional fuel cell membrane suffers from fuel cross over and high degree of swelling after extensive operation. To circumvent these deficiencies, we disclose in this study proton conducting membrane by incorporating poly(ether sulfones)(PES) with sulfonated poly(ether ether ketone)(sPEEK, degree of sulfonation=50%) prepared under electric field poling condition. The external field enhanced the aromatic chain ordering from both sPEEK and PES and improved the miscibility. This external force is conducive to the formation of more densely packed and ordered hydrophobic domain that eventually leads to long range ordered hydrophilic proton conducting channels. The averaged hydrophilic dimension is smaller than that in generic sPEEK, thus displayed much lower methanol permeability (3.17x10-7 cm2/s), and lower swelling ratio (31.20%). However, the conductivity (7.43x10-2 S/cm) is higher compared to sPEEK at 64% degree of sulfonation, and comporable with Nafion. The binary composite is highly durable; and shows improved membrane mechanical strength, possibly due to the densification of amorphous domain. Nearly 50% increase of DMFC power output is observed using this membrane, and the best power density is recorded at 150mA/cm2 (80 oC, 1M Methanol).
An Equivalent Circuit Model for Electrochemical Systems
Authors: Yamada Hidenori , Bandaru Prabhakar R
Published: February 2020

Our recent work on modeling electrochemical (EC) energy storage devices has indicated more clearly the similarities and differences between ultracapacitors and batteries.  In addition, the introduction of nanostructures into such EC storage devices introduces new physics based on the consideration of the density of states (DoS), especially in the form of quantum capacitance CQ [1].  Here, we propose an equivalent circuit model which describes EC storage deploying either traditional three-dimensional electrodes or lower-dimensional electrodes.  The circuit has two separate branches: the ultracapacitor branch which involves the device double-layer capacitance and CQ (the latter being chiefly for low DoS electrodes), and a battery related branch which was modeled through diode-like characteristics with the diode characteristic of charging and discharging current in response to overpotential.  It will be shown how the equivalent circuit closely models and agrees with experimental data on carbon nanotube based electrodes [1], and details related to the model validation will be discussed.  The proposed equivalent circuit would explain, for the first time, the intrinsic capacitor-like and battery-like characteristics of any EC device in a unified manner.

[1] H. Yamada and P. R. Bandaru, Appl. Phys. Lett. 102, 173113 (2013), ibid 104, 213901 (2014).
Li2ZrO3 -Coated Li1.2Ni0.2Mn0.8O2 for the High Performance Cathode Material in Lithium Ion Batteries
Authors: Noh Hana , Lee Yongho , Kim Hyeongwoo , Choi Wonchang
Published: February 2020

Introduction

Recently, high energy density lithium ion batteries (LIBs) play an important role in the field of portable and electronic devices and electrical vehicles. Although conventional layered LiCoO2 cathode material has good electrical properties, the capacity of current LiCoO2 is around 160 mAhg-1 with lithium utilization in the structure less than 50%. Moreover, their cost and safety requirement are still problems for the adoption of lithium ion technology for these large-battery application. In this reasons, during the past two decades, several cathode materials have been emerged as an alternative layered structure compounds, such as olivine phosphates (LiMPO4; M = Fe, Co, Ni, and Mn) and spinel oxides (LiM2O4; M = Mn, Ni and Co), however these still have a relatively low capacity. To overcome this problem, Over-lithiated Layered Oxide (OLO) materials have been considered one of the promising cathode materials for the next generation of cathode materials. Among them, 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2 which is known as high capability (250 mAhg-1) has excellent electrochemical performance and stability at higher cut-off voltage beyond 4.8 V. However, its severe capacity fading during high current rates is generally related to the unstable structure and the side reaction with electrolytes cause problems while cathode carries out beyond 4.8 in a range of high voltage. Herein, we reports Li2ZrO3 -coated Li1.2Ni0.2Mn0.8O2 for high performance cathode material in lithium ion batteries. The concept is both to decrease the interface resistance by crystallization of the surface layer and cover the particles with Li2ZrO3that would suppress the particles against side reactions with the electrolyte. In addition, it can circumvent the loss of transition-metal ions of oxygen, without changing the electronic and ionic conductivities. In this study, X-ray diffraction, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, Electrochemical Impedance Spectroscopy and various Charge-discharge measurements were also performed to further investigate the effect of surface-coating layer.

 

Experimental

To make samples, OLO was made by adding Zirconium isopropoxide was added in the mixed powder and then mixed by hand. After pelletizing, it was put in Alumina crucible and calcinated in 900 °C for 10 hours (heating rate is 5 °C/min). After calcination, powder was filtered using D.I water to remove the residue of LiOH. Resulting powder was dried at 60oC (overnight). Electrode slurry has been made of 92% of cathode materials, 4% of Denka black, 4% of PVdF. The slurry was casted on the Al foil for current collector and assembled with 2032 coin cell.

Result and discussion

Surface modification of cathode electrodes with lithium zirconia oxide gives rise to the better rate properties than pristine OLO.

Figure 1