bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Simple Synthesis of an Excellent Oxygen Reduction Catalyst: Nitrogen-Doped, Sharply-Mesoporous Carbon from Magnesium Salts
Authors: Eisenberg D. , Yan Ning , Rothenberg Gadi , Mabayoje Oluwaniyi , Mullins Charles Buddie 
Published: February 2020

Any new oxygen reduction catalysts for practical low-temperature fuel cell applications must compete with the commercial platinum catalysts on efficiency and cost. Mesoporous nitrogen-doped carbon (N:C) has emerged as a leading alternative, mostly due to its high surface area, and the promise for low-cost production. While the best mesoporous N:C catalysts in the literature can operate on par with commercial platinum/carbon composites,1 their synthesis is complex and difficult – increasing their cost and rendering them impractical.
We present a particularly simple synthesis of N-doped carbon, starting from magnesium salts of nitrogen-containing ligands. Pyrolysis of the salts proceeds by the little-researched mechanism of self-templating – formation of similarly sized MgO nanoparticle cores, which are then washed out with dilute acid, leaving behind a narrow pore size distribution.
These carbons have high surface areas (>1400 m2/gr), nitrogen doping levels topping what is required for catalysis (>4%), and most interestingly, a very narrow pore size distribution (ranging from 10 to 20 nm for different carbons). Tested in alkaline ORR catalysis, these carbons compete successfully with commercial platinum-based electrodes, so they are efficient, cheap, and simple to prepare.
(1) W. Wei, H. Liang, K. Parvez, X. Zhuang, X. Feng, K. Müllen, Angew. Chem.
2014, 126, 1596.
Development of Energy-Efficient Thermal Management System for Proton Exchange Membrane Fuel Cell and Reformer
Authors: Sundar Pethaiah Sethu , Subiantoro Alison 
Published: February 2020

The rising energy cost and limited supply of fossil fuel make it important for an alternative renewable energy source. Of all the alternatives, proton exchange membrane (PEM) fuel cell is very promising due to its high efficiency and zero emission characteristics. A fuel cell converts chemical energy to electricity by combining hydrogen with air. However, hydrogen storage poses a lot of practical challenges. Hence, alcohol based steam reforming systems are widely used for on-site hydrogen generation instead. During operation, a fuel reformer needs heating to maintain its temperature. At the same time, the fuel cell stack needs cooling to maintain its temperature. Currently, separate heating and cooling systems are used, resulting in an inefficient thermal management system.
In this study, a more efficient thermal management system is proposed. It incorporates a vapor compression refrigeration (VCR) system to a reformer - PEM fuel cell unit. A VCR system can be seen as a device that transports heat from one place to another with a very high efficiency. In this application, heat is removed from the stack and is transferred to the reformer. This method will save around 38% of energy as compared to the conventional thermal management system.
Lithium Battery Using High Conducting Emifsi-Doped Solid Polymer Electrolytes Process Under the Electric Field
Authors: Chang Alice Yi-han , Chu Peter Po-jen 
Published: February 2020

Lithium-ion battery holds great promises for future energy storage purpose. However, traditional Lithium-ion battery uses liquid organic electrolytes which is flammable and leads to safety problems. In this work, we present a highly ion conducting membrane which is discovered by doping a nonvolatile conducting medium, ionic liquids (ILs) in solid polymer electrolytes (SPEs) prepared under external electric field(EF) poling. The poling created aligned morphology in PVDF-HFP and PMMA blending system yield the long-range ordered but nearly totally amorphous domains where nonflammable ionic liquids is inter-dispersed to display unusually high Li+ transport with room temperature conductivity reaching over 10-3S/cm. The highest conductivity of 7.53x10-3 S/cm is observed for polymer electrolyte containing PMMA/PVDF-HFP (50/50 wt%, eV8E2L). The alignment by the external electric field not only altered the interaction between polymer components which suppressed PVDF-HPF crystallinity in the SPEs, it also improves mechanical strength of the membrane .The coin cell (R2032) using eV8E2L as the SPEs and LiFePO4 cathode shows fair half-cell performance and durable cycle stability. Under 0.1C-rate the half-cell displayed consistent discharge capacity of 140 mAh/g , without apparent capacity decay.

Figure 1
Silicon Non-Metal Compounds As New Promising Materials for Lithium Ion Batteries
Authors: Reinhold Romy , Stoeck Ulrich , Ahrens Eike , Eckert Jürgen , Kaskel Stefan , Giebeler Lars 
Published: February 2020

Due to an increasing energy demand caused by an expanding global population and the rapid development of new technologies, a high priority to a further development of new battery systems is given. In fact, there is a great interest in Lithium Ion Batteries as they offer a high energy density and a high rate capability [1]. Owing to a high theoretical capacity silicon is a promising anode material to replace commercially used graphite [2]. The electrochemical energy storage originates from an alloying-dealloying mechanism where different lithium-silicon phases like Li12Si7, Li15Si4 or Li22Si5 were formed [2]. This mechanism conducts capacity fading caused by volume expansion during the insertion and extraction of lithium ions. Therefore, nanostructured silicon is expected to meet future criteria defined for new electrochemical energy storage systems.
A new promising way to produce silicon nanoparticles is the application of silicon non-metal compounds and their decomposition through an electrochemical in situ conversion mechanism. In addition, the non-metal serves as a Li-containing matrix that buffers the volume expansion during charging and discharging. Moreover, the synthesis of silicon non-metal compounds via planetary ball mill is environmentally benign and easy scalable.
Initial studies show that phase-pure produced silicon diphosphide (SiP2) is electrochemical active over a wide potential range. The first discharge cycle reaches a capacity closely to theory (about 3100 mAh/g). Continuous cycling is stable about 100 cycles. Cyclic voltammetry experiments give an insight into the behavior of the redox properties of materials which is in this case very similar compared to pure silicon. From this observation a similar reaction of silicon diphosphide as known from silicon is indicated. Ex situ XRD results confirm the proposed reaction mechanism and refers to the formation of lithium phosphide which serves as buffering matrix. The production of smaller particles is challenging and the large capacity fading after the first cycle needs to be explained and to be overcome. Both points are taken as prospective tasks.
[1] C.-M. Park, J.-H. Kim, H. Kim, H.-J. Sohn: Li-alloy based anode materials for secondary batteries. In: Chem. Soc. Rev. VI. 39, 2010, S. 3115–3141.
[2] S. Goriparti, E. Miele, F. De Angelis, E. De Fabrizio, R. P. Zaccaria, C. Capiglia: Review on recent progress of nanostructured anode materials for Li-ion batteries. In: J. Power Sources VI. 257, 2014, S. 421–443.
Metal Complex and Organic Compounds Modified Electrode Used As a Mediator for the Redox-Flow Batteries
Authors: Sato Yukari , Narita Ayumi , Kaneko Yuji , Negishi Akira , Nozaki Ken , Kato Tohru 
Published: February 2020

Redox-flow batteries, which are using organic compounds, aqueous solution, and new metal complexes, have been actively investigated. Non -metal redox-flow batteries are strongly expected by the increasing in needs for low-cost, safe, and trusted energy storage applications. Both of redox active materials and cell systems of redox-flow batteries have made rapid and great progress in recent years. Redox-flow batteries are investigated frequently, and are now in a transition stage.
Recently, redox-flow batteries using organic compounds and metal complexes (or inorganic materials) as active materials were investigated. In such cases, redox potentials and efficiencies of electron transfer of each active materials on the electrode surface will be quite important as with the stability of the active materials. If we can control the redox potentials of organic/inorganic active materials flexibly, we will be able to receive suitable systems.
The electrode modified with self-assembled monolayers having electrochemical active sites have been often adopted as mediator for controlling the redox reaction of other electro active species in the electrolyte solution. In our previous studies, ferrocene derivatives attached on the gold electrode worked as suitable mediator for the reduction of Fe(III) ion in solution (1). On the other hand, same ferrocene derivatives on the electrode did not work as the mediator of the K4Fe(CN)6 ion at all. Although redox potentials of both Fe(III) and K4Fe(CN)6 were ca. +0.4 V (vs. SCE) in the acidic solution (1M HClO4), ferrocene attached electrode only mediated for Fe(III) oxidation. Electrochemical properties of quinone/ hydroquinone modified electrodes were also reported previously (2) (3). In the case of quinone-modified electrode, the redox potential of quinone species was controlled stably by changing solution pH. We newly investigate suitable mediator attached on the electrode /substrate surfaces for constructing all organic-aqueous redox-flow battery.
References
(1) Y. Sato, H. Itoigawa and K. Uosaki, "Unidirectional Electron Transfer at Self-Assembled Monolayers of 11-Ferrocenyl-1-undecanethiol on Gold", Bull. Chem. Soc. Jpn., 66, 1032 - 1037 (1993).
(2) Y. Sato, M. Fujita, F. Mizutani, and K. Uosaki, "Electrochemical Properties of 2-Mercaptohydroquinone Monolayer on Gold Electrode. Effect of Solution pH, Adsorption Time and Concentration of Modifying Solution", J. Electroanal. Chem., 409, 145 -154 (1996).
(3) S. Ye, A. Yashiro, Y. Sato, and K. Uosaki, “Electrochemical in situ FT-IRRAS Studies of Self-Assembled Monolayer of 2-(11- Mercaptoundecyl)hydroquinone”, J. Chem. Soc., Faraday Transaction, 92, 3813 - 3821 (1996).
Three-Dimensional Graphene Network As a Highly Macro-Porous, Flexible and Large-Scale Electrode for Supercapacitor Application
Authors: Lin Che-Hsien , Tsai Chuen-Horng , Tseng Fan-Gang , Hsieh Chien-Kuo 
Published: February 2020

Graphene, a two-dimensional (2D) carbon nanomaterial, was widely used in many electrochemical applications due to their high mechanical strength, good chemical stability, high specific surface area, and excellent electrical conductivity. However, the major concern for those applications was the activity reaction surface area of the 2D plane structure of graphene. Therefore, in order to enhance the reaction surface area of graphene, the development of a highly porous network-macrostructure with large surface area three-dimensional graphene is an effective strategy to be achieved for electrochemical applications.
In this study, we reported an effective and simple method to prepare highly macro-porous, large-scale and flexible three-dimensional graphene foam (3D GF) which was synthesized on the commercial nickel network via the chemical vapor deposition (CVD) method. The quality of 3D GF was investigated by using a Raman spectroscopy. A field-emission scanning electron microscopy was used to examine the surface morphology of 3D GF. A high-resolution transmission electron microscopy was utilized to analyze the inter-layer distance and the number of layers of graphene. Raman results revealed the highly uniform performance of the large-scale 3D GFs. The cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS) were carried out to examine the electrochemical properties. Compared with the traditional 2D plane-structure graphene synthesized on the Ni foil, the CV and EIS results measured by the 3D GF confirmed its superior capacitive behavior, higher specific surface area, and also demonstrated the excellent power capabilities with a low solution resistance and charge transfer resistance. It was found that the specific capacitance of 3D GF was three times larger than the traditional 2D plane-structure graphene. In this study, a tube furnace thermal CVD was utilized to synthesize the large-scale 3D GF. The Ni forms can be curled and loaded into the tube furnace for CVD processes to fabricate the large-scale 3D GFs easily. We provided an easy method to fabricate the highly macro-porous, large-scale and flexible 3D GFs for the future graphene-based potential applications.
Understanding of Capacity Loss/Fading of Li-Rich Layer-Structured Cathode Materials Based on Structural/Electrochemical Analyses
Authors: Fung Kuan-Zong , Tsai Shu-Yi , Ni Chung-Ta , Lin Wei-Zhi , Huang Bo-Yuan 
Published: February 2020

Li-rich layer-structured cathode materials formulated as xLi2MnO3 -(1-x)LiMO2(M = Mn, Ni, Co, etc.) have received much attention due to their surprisingly high reversible capacity for Li-ion battery applications. For the understanding of these materials, a systematic study on complicated crystal structures and reaction mechanisms during electrochemical charge/discharge cycles is employed. Although Li-rich layer-structured cathode material show a reversible capacity as high as 250 mAh/g at low rate, its electrochemical properties such as capacity loss at first cycle, rate capability and capacity fading still need to be examined and characterized. In this study, several compositions of xLi2MnO3 -(1-x)LiMO2 (M = Mn, Ni, Co, etc.) were investigated.
The TEM structural analysis shows that the evidence of spinel phase after cycling. It is believed that the transition from layered structure to spinel structure may induce a large lattice distortion resulting in lattice breakdown and capacity. In additions, the phase transition is caused by the redox reaction of transition metal ions through charging/discharging tests. Thus, the cycling behavior of Li-rich layer-structured oxides is studied by changing the oxidation state of transition metal ions in the layered structures. XRD, SEM, TEM will be used for characterization of cycled cathode materials.
Modified Separator Using Inactive Materials from the Cathode for Advanced Lithium Sulfur Batteries
Authors: Liu Naiqiang , Huang Yaqin 
Published: February 2020

Lithium sulfur batteries become the promising candidate to develop the high-energy density rechargeable battery for electric vehicles and energy storage systems. The theoretical specific energy of the lithium-sulfur battery is 2600 W h/kg, which is much higher than lithium-ion batteries. 1 However, the commercialization of the lithium sulfur batteries has been hindered by its poor cyclability, short cycle life and low coulombic efficiency.2-3 The carbon interlayer modified separator provided a promising method to improve the electrochemical performance of lithium-sulfur battery. The carbon layer faced to the cathode blocks polysulfides in the cathode side and restrains the polysulfide shuttling during electrochemical reaction.4-5

We describe in this work a carbon interlayer modified separator design by the inactive materials from the cathode. The carbon layer coated on the separator is thin and lightweight. In addition, the method using the redistributed inactive materials avoid the added weights of the battery involved. This design will be beneficial to ensure the high-energy density of lithium sulfur batteries. After 150 cycles, the batteries retain a reversible capacity of 644 mAh g-1at the rate of 0.5 C, showing a low capacity decay of about 0.11% per circle (Figure 1).
Figure 1 Long cycle performance of Li-S batteries with modified separator at 0.5C.

Reference

1. Peled, E.; Gorenshtein, A.; Segal, M.; Sternberg, Y. Rechargeable Lithium-Sulfur Battery. J. Power Sources 1989, 26, 269-271.
2. Mikhaylik, V. Y.; James, R. A. Polysulfide shuttle study in the Li/S battery system. J. Electrochem. Soc. 2004, 151, A1969-A1976.
3. Diao, Y.; Xie, K.; Xiong, S.; Hong, X. Analysis of polysulfide dissolved in electrolyte in discharge-charge process of Li-S battery. J. Electrochem. Soc. 2012, 159, A421-A425.
4. Chung, S. H.; Manthiram, A. Bifunctional Separator with a Light‐Weight Carbon‐Coating for Dynamically and Statically Stable Lithium‐Sulfur Batteries. Adv. Funct. Mater. 2014, 24, 5299-5306.
5. Zhou, G.; Li, L.; Wang, D. W.; Shan, X. Y.; Pei, S.; Li, F.; Cheng, H. M. A Flexible Sulfur‐Graphene‐Polypropylene Separator Integrated Electrode for Advanced Li–S Batteries. Adv. Mater. 2015, 27, 641-647

Acknowledgement: Financial support from the National Science Foundation of China (no. 51272017) is gratefully appreciated.

Figure 1
Novel Cobalt-Rich Composite (CRC) Cathode and Siox Anodes for High-Energy Li-Ion Batteries
Authors: Lopez Herman , Bowling Charles , Hernandez Pedro , Karthikeyan Deepak , Kumar Sujeet , Li Bing , Sharma Sanjeev , Venkatachalam Subramanian 
Published: February 2020

The increasing sophistication and functionality of mobile devices coupled with the human dependence for the devices leads to a strong demand for high performance batteries. Over the years, improvements in battery performance have taken place with minor enhancements resulting from improvement in cell design such as increasing the active material content, increasing the electrode density and reducing the weight and thickness of the inactive cell components. Further improvements by cell optimization are quickly reaching their limits creating a shift in focus to new active electrode material that are expected to result in the next leap in cell performance.
In this work, Cobalt-Rich Composite (CRC) cathodes have been developed by modifying standard low voltage LiCoO2 (LCO) and stabilizing the structure by forming high Nickel and Manganese containing composites. The resulting CRC cathode shows surprisingly stable high voltage performance compared to LCO as shown in Figure 1. Traditionally the structure of LCO cathode falls apart at high charge voltages (>4.35V) when >0.5 moles of Li are extracted from the structure. The CRC cathode enables high electrode active content (>97%) and density (>4.0g/cc), high average voltage and high specific capacity required for high-energy cells. To complement the CRC cathode, a high capacity SiOx-based anode electrode has been developed. Current lithium ion cells continue to use graphite as the anode of choice. Si-based anodes have been widely studied as a possible replacement to graphite due to their high specific capacity (~4000mAh/g). Unfortunately Si-based materials suffer from large volume expansion resulting in pulverization and poor cycle life. However, by precise engineering the anode electrode formulation, binder and active material, high capacity SiOx-based anode electrodes with high percent active content (>80%) have been developed and shown to cycle well.
Figure 2 shows 1Ah pouch cell data from cells integrating CRC cathode and SiOx anode, showing high specific energy of 285Wh/Kg and cycle life of ~450 cycles before reaching 80% capacity retention at C/5 rate. Swelling and abuse testing of the cells meet consumer electronics specifications and results will be presented. Figure 3 shows that by engineering the cell design and increasing the cell footprint, 10Ah capacity pouch cells integrating CRC cathode and SiOx anode with specific energy of ~350Wh/Kg have been made enabling automotive and drone applications. This presentation will also cover remaining challenges associated with CRC cathode and SiOx anode with respect to synthesis, performance and cell manufacturing to bring these materials and cell technology from prototypes to large-scale manufacturing.

Figure 1
In Situ AFM Study of Solid Electrolyte Interface in Lithium-Ion Batteries
Authors: Shen Cai 
Published: February 2020

Chemical and morphological structure of solid electrolyte interphase (SEI) plays a vital role in lithium-ion battery (LIB), especially for its cycleability and safety. To date, research on SEI is quite limited due to the complexity of SEI and lack of effective in situ characterization techniques. Here, we present real-time views of SEI morphological evolution using electrochemical atomic force microscopy (EC-AFM). Complemented by an ex situ XPS analysis, fundamental differences of SEI formation from ethylene carbonate (EC) and fluoroethylene carbonate (FEC)-based electrolytes during first lithiation/delithiation cycle on HOPG as well as Fe3O4 electrode surfaces were revealed. Our results showed that SEI layer formed by reductive decomposition of the EC/DMC electrolyte was principally composed of alkyl carbonates ROCO2Li, while the SEI layer formed by FEC/DMC electrolyte was mainly composed of LiF. Only trace of Li2CO3was found in the SEI layer formed from FEC/DMC electrolyte. The dense and hard nature of SEI formed by FEC/DMC electrolyte can protect the graphite against dendrite formation and could be the reason for better cyclability of FEC/DMC electrode as compared to those of EC/DMC based electrolyte. For the Fe3O4 anode, it was found that Fe3O4 electrode was unable to form a stable SEI layer on the electrode surface which resulting in electrolyte decomposition. FEC-based electrolyte can help to improve the performance of Fe3O4 anodes in lithium ion batteries but its protective effects are far from perfect. To accelerate the application of Fe3O4 or other metal oxide anodes in lithium ion batteries, better electrolytes and sophisticated carbon coating techniques are needed warrant formation of a stable SEI layer.
Conventional method to evaluate electrolytes are usually complex and tedious procedures. Thus, combination of in situ electrochemical AFM and ex situ XPS could potentially serve as a fast diagnostic tool to evaluate the properties and quality of SEI formed on different electrodes from diverse electrolytes and additives.
(Invited) On the Way to Molecular Building Blocks for Next Gen OPV
Authors: Hummelen Jan 
Published: February 2020

We have recently predicted that when the dielectric constant of organic semiconductors is increased from 2-4 to >10, a dramatic increase in (maximal) power conversion efficiency of organic solar cells, based on these materials as active layer constituents, can be achieved.1-3 Binding energies of initial excitons, of charge transfer excitons, and between charges in any type of recombination process are diminished with increasing electric permittivity of the medium.
In order to design and develop new molecular materials with higher dielectric constant, the next challenge is to make the connection between the dielectric constant, as a macroscopic property, and molecular structure.
One approach is to connect suitable substituents to known (opto)electronically functional molecular moieties. We report here on the design and preparation of molecules bearing substituents that are to enhance the dielectric properties without diminishing other crucial parameters (like charge carrier mobility, bandgap, stability, etc.).4,5 Another approach is to design inherently more polarizable/polar chromophores. A new class of conjugated polymers, based on this principle is presented.6

Through a computational chemistry approach, we investigate the influence of molecular moieties on the relative energies of various charge separated states resulting from photo-induced charge transfer between molecular donors and acceptors. We report on a system in which the energies of the charge separated states are tuned to a favorable situation by proper placement of dipolar substituents.7

1. L. J. A. Koster, S.E. Shaheen, J.C. Hummelen, Adv. Energy Mater. 2012, 2, 1246.
2. R.C. Chiechi, J.C. Hummelen, ACS Macro Lett. 2012, 1, 1180.
3. R. C. Chiechi, R. W. A. Havenith, J. C. Hummelen, L. J. A. Koster, M. A. Loi, Materials Today 2013, 16, 281.
4. F.Jahani, S. Torabi, R.C. Chiechi, L. J. A. Koster, J. C. Hummelen Chem. Commun. 2014, 50, 10645.
5. S. Torabi, F.J.Bahnamiri, I. Van Severen, C. Kanimozhi, S. Patil, R.W.A. Havenith, R.C. Chiechi, L. Lutsen, D.J.M. Vanderzande, T.J. Cleij, J.C.Hummelen, L.J.A.Koster, Adv. Funct. Mater. DOI 10.1002/adfm.201402244 (2014)
6. T. P. Voortman, H. D. de Gier, R.W. A. Havenith, R. C. Chiechi, J. Mater. Chem. C, 2014, 2, 3407
7. H. De Gier, R. Broer, R.W.A. Havenith, Phys.Chem.Chem.Phys., 2014, 16, 12454