bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photo-Induced Effects in Graphene Channels When Interfaced with Quantum Dot Array
Authors: Miao Xin , Samarth Trivedi , Grebel Haim 
Published: February 2020

Field effect transistors with graphene channels were interfaced with semiconductor quantum dot (QD) array. Electrical characteristics and opto-electronic behaviour of the elements were assessed. Relative photo-resistance (the difference in channel resistances under dark and under light conditions and normalized by the channel’s resistance) was observed as a function of drain-source potential.
Graphene – a mono layer thick crystalline form of carbon - portrays high conductivity, chemical inertness, mechanical robustness and unusual dispersion relations [1]. Characteristics of free-standing, mono and bi-layer graphene have been studied when deposited over nano-pore array of anodized aluminum oxide (AAO) substrate. One may postulate that QDs, filling the pores, will have a profound effect on the graphene channel. Such arrangement led to the realization of the first visible surface plasmon laser [2].
The field effect transistors (FET) were fabricated on oxidized silicon wafers. They were composed of graphene channels and two metal electrodes, used as drain and source electrodes. The silicon wafer served as a back gate electrode. Contacts to the graphene were found Ohmic. Aluminum, was deposited on the oxidized silicon wafer and was anodized according to our previous recipe. Core-shell semiconductor CdSe/ZnS QDs were imbedded in the anodized aluminum pores and the semi-transparent graphene was deposited on top of the anodized layer.
Unlike ordinary graphene channels, the current between the drain and source, Ids, decreased as a function of gate bias, Vgs. When illuminated by a 50 mW/cm2 white light source, the channel exhibited a clear relative differential resistance at Vds=0.3 V. This behavior was attributed to a negative differential resistance effect.
[1] A. C. Ferrari, J. C. Meyer, V. Scardaci, M. Lazzeri, F. Mauri, S. Piscance, D. Jiang, K. S. Novoselov, S. Roth and A. K. Geim, “Raman Spectrum of Graphene and Graphene Layers”, Phys. Rev. Lett., 97, 187401 (2006).
[2] R. Li, A. Banerjee and H. Grebel, “The possibility for surface plasmon lasers”, Optics Express, 17, 1622-1627 (2009).
[3] S. W. Lee, A. Kornblit, D. Lopez, S. V. Rotkin. A. Sirenko, H. Grebel, “Negative Differential Resistance: Gate Controlled and Photoconductance Enhancement in Carbon Nanotube Intra-connects”, Nano Letters, DOI: 10.1021/nl803036a (2009).
Controllable Synthesis of Metal Nanoparticle/Graphene Nanoribbon Composites
Authors: Wang Shan-Yu , Chiang Wei-Hung 
Published: February 2020

Graphene nanoribbons (GNRs) represent a new structure of carbon nanomaterials which have exceptional physical and chemical properties, making them can be potentially used in the applications of energy, composites, biomedical and electronics [1-3]. Recently composites of metal nanoparticles (NPs) decorated on GNR surfaces has been reported as novel materials with exceptional properties and can be used for industrial applications [4, 5]. For example, Pt/GNRs and Pd/GNRs using as catalysts for fuel cells, and Ag/GNRs can be used for conductive ink or biomedical applications. Consequently, the development of synthetic method to produce metal NPs/GNR composites will lead to important advances on both fundamental study and innovative applications.
Here we report a controllable synthesis of Ag/GNR composites using a two-step reaction route. First, we synthesized and functionalized GNRs by a facile carbon nanotube chemical unzipping. The functionalization of GNRs could be tuned by controlling reaction conditions (temperature, time, and oxidant concentration), confirming by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XP)S characterizations (Fig. 1 and 2). Ag NPs can be decorated onto the GNR surface through a wet- chemical-based redox reaction. In our present experiment, we found that the particle size, morphology and distribution of Ag NPs can be further controlled by controlling the reaction conditions. Detailed materials characterizations including SEM and UV-Vis spectroscopy (Fig. 3) show that Ag/GNR composites were successfully synthesized in our experiment.

Reference

[1] L. Ma, J. Wang, and F. Ding, "Recent progress and challenges in graphene nanoribbon synthesis," Chemphyschem, vol. 14, pp. 47-54, Jan 14 2013.

[2] D. V. Kosynkin, A. L. Higginbotham, A. Sinitskii, J. R. Lomeda, A. Dimiev, B. K. Price, et al., "Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons," Nature, vol. 458, pp. 872-6, Apr 16 2009.
[3] A. L. Higginbotham, D. V. Kosynkin, A. Sinitskii, Z. Sun, and J. M. Tour, "Lower-defect graphene oxide nanoribbons from multiwalled carbon nanotubes," ACS nano, vol. 4, pp. 2059-2069, 2010.
[4] P. T. Yin, T.-H. Kim, J.-W. Choi, and K.-B. Lee, "Prospects for graphene–nanoparticle-based hybrid sensors," Physical Chemistry Chemical Physics, vol. 15, pp. 12785-12799, 2013.
[5] L. Xu, G. Yang, H. Jing, J. Wei, and Y. Han, "Ag–graphene hybrid conductive ink for writing electronics," Nanotechnology, vol. 25, p. 055201, 2014.

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Aerogels: Graphene and Beyond
Authors: Worsley Marcus A. 
Published: February 2020

Aerogels are porous solids used in a wide range of applications including sorbents, filtration, insulation, hydrogen storage, catalysis, batteries, and supercapacitors. Their unique properties are related to their high internal surface, low-density, and small pore/particle size. Two-dimensional (2D) nanomaterials, such as boron nitride and graphene, also exhibit a range of distinct optical, electronic, and mechanical properties, but are typically limited to thin films and coatings. Assembling 2D nanomaterials into monolithic aerogels expands their application space to include technologies and manufacturing processes that require a macroscopic 3D form factor. Furthermore, placing the novel intrinsic properties of 2D materials in a low-density, high surface area architecture has the potential to unlock exciting new properties and features only displayed in the aerogel system. Here, we present synthesis schemes for aerogels made from several different 2D materials, (e.g. boron nitride, graphene, dichalcogenides, etc.). Hybrid aerogel synthesis, combining two or more layered materials, will also be presented. Characterization of aerogels will include textural, transport, mechanical properties, and more. Results will be discussed in light of theory and existing literature.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
An Electrochemical Analogy to the Fuel Injector: The Electrochemical Direct Injection Reactor
Authors: Davies Greg , Hsieh Andrew , Steingart Daniel A 
Published: February 2020

ElectroChemical Direct Injection (ECDI) is a newly proposed battery architecture. ECDI involves the direct injection of small quantities of cathode and anode materials into a reactor, where they are rapidly discharged, then flushed out. The process repeats, and much like a standard combustion engine, the quantity of fuel injected, in addition to the rate of discharge, can be tailored to meet the power demand in an efficient way. We investigate some of the most interesting electrochemical and mechanical features of the system, and present some key results illustrating the promise of such an approach. Results from the discharge rate performance and energy efficiency of the system are presented, to highlight the benefits of this architecture.
From an electrochemical perspective, using a high-surface area, nano-structured zinc [1], we demonstrate that high discharge utilization efficiencies (% of theoretical capacity) are possible in this free standing system. At 3C rates of discharge, efficiencies of up to 80% are achievable with this zinc morphology. Even at rates up to 30C, efficiencies are up to 50% are still achievable. The system can be improved through optimization of the electrolyte, and with various additives. The benefits of electrolyte optimization and additives will be discussed, including a mechanistic study of the additives.
Cost-Effective All-Copper Flow Battery Using Flowable Slurry Electrode for Large-Scale Energy Storage
Authors: Agar Ertan , Nagelli Enoch A. , Sinclair Nicholas S. , Hoyt Nathaniel C. , Stricker Elizabeth A. , Savinell Robert F , Wainright Jesse S. 
Published: February 2020

One major issue limiting the implementation of renewable energy sources is the lack of efficient, cost-effective, and reliable energy storage technologies. Recently, vanadium redox flow batteries (VRFBs) have gained a significant interest as a promising electrochemical technology for large-scale energy storage due to their ability to decouple energy and power ratings and to store energy efficiently [1]. However, the high capital cost of vanadium-based electrolyte represents a major bottleneck for the commercialization of these systems [2]. By this motivation, in this study, a novel all-copper flow battery (CFB) using flowable slurry electrode is introduced.
CFBs have a great potential for commercialization, as copper is a less toxic, widely abundant, and less expensive element than vanadium [3]. Moreover, its relatively smaller cell potential eliminates hydrogen evolution as a side reaction. However, electrochemical-plating of copper within the negative electrode during charging recouples energy and power ratings, which limits the widespread implementation of these systems. In order to mitigate this issue, a flowable slurry electrode strategy is implemented for the negative half-cell instead of using a conventional, stationary electrode [4-5]. A schematic of an all-copper flow battery using a flowable slurry electrode for the negative half-cell is shown in Fig. 1. The slurry electrode carries the deposited metal out of the stack to the reservoir, allowing the energy and power capabilities of the battery to be scaled independently.
This study is investigating the performance of a CFB using a flowable slurry electrode with a novel copper-bromide chemistry by conducting polarization curve (Fig. 2), battery cycling and efficiency analyses. As seen in Fig. 2, with the copper-bromide electrolyte and flowable slurry electrode strategy, much higher operating current densities (maximum power density of ~85 mW/cm2 obtained at 200 mA/cm2) have been reached compared to literature values for an all-copper flow battery. This indicates that the slurry electrode cannot only de-couple the energy and power ratings, but can also provide an acceptable level of polarization losses.

References:

[1] A. Z. Weber, M. M. Mench, J. P. Meyers, P. N. Ross, J. T. Gostick, Q. Liu, J. Appl. Electrochem., 41, 1137-1164 (2011).
[2] R. M. Darling, K. G. Galagher, J. A. Kowalsky, S. Ha, F. R. Brushett, Energy Environ. Sci., 7, 3459-3477 (2014).
[3] L. Sanz, D. Lloyd, E. Magdalena, J. Palma, K. Kontturi, J. Power Sources, 268, 121-128 (2014).
[4] T. Petek, N. C. Hoyt, J. S Wainright, R. F. Savinell, Submitted to J. Power Sources, March (2015).
[5] T. Petek, N. C. Hoyt, J. S Wainright, R. F. Savinell, Submitted to J. Electrochem. Soc., March (2015).
[5] T. Petek, N. C. Hoyt, J. S Wainright, R. F. Savinell, Submitted to J. Electrochem. Soc., March (2015).

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Cost Effective Electrochemical Energy Storage Today and Tomorrow: Promising Pathways to $100 per k Wh
Authors: Gallagher Kevin G. , Crabtree George 
Published: February 2020

Cost effective electrochemical energy storage is the key to unlocking the future potential of zero emission automobiles and a stable electricity grid that utilizes large fractions of inherently variable renewable sources of power. Lithium-ion battery costs are continuing on a downward trajectory that has enabled automakers around the world to produce battery electric vehicles and sell them at moderate to high prices. The steeply declining cost curve has also enabled this technology to spill-over into early, high-value segments of energy storage on the electricity grid. As the push-pull between technology and marketplace continues, lithium-ion and other established battery chemistries will fight for dominance with gasoline fueled vehicles in transportation and with inexpensive and efficient combined cycle gas turbines in large scale grid storage applications. Concurrently, scientists and engineers around the world are racing to build cheaper, longer-lived, more energy dense batteries based on new chemistries. These promising new beyond lithium ion storage technologies with higher performance and lower costs are seen as necessary to enable a true renaissance in the way society utilizes electricity. Cost structures for historical and projected battery technologies will be presented. Pathways to achieve a battery level price of $100/kWh will be shown in terms of materials level performance and cost targets to guide researchers and policy makers.
Intrinsic Degradation Variability in Commercial Lithium-Ion Batteries
Authors: Devie Arnaud , Dubarry Matthieu , Liaw Bor Yann 
Published: February 2020

Lithium-ion batteries have first been introduced to market for consumer electronics applications where safety and reliability requirements are less stringent than in industrial applications. 18650-format cells in particular have encountered great success in the laptop industry and the manufacturing processes have matured to the point where 18650 cells found their way into new markets such as personal transportation or energy storage systems. Because 18650 cells are a commodity, they face typical manufacturing process variability which can be an issue with these larger scale battery systems. Indeed, where a laptop battery consists of 2 to 4 cells in series, the battery found in a passenger vehicle such as the Tesla Model S can consist of a series cells count in excess of 100. When taking into account the need for long-term reliable operation of the battery pack and the cost burden associated with premature battery pack failure, it seems critical to ensure long-term performance of the battery pack. Unfortunately, a battery pack is usually as weak as its weakest cells.
Battery pack’s early-life performance and reliability are usually attained by sorting and matching cells used in a battery pack. This mitigation technique has its limits though as it cannot account for the long-term degradation spread of the individual cells composing the battery pack. This degradation spread within a battery pack can have various origins. One of them can be the temperature gradient resulting from the spatial distribution of cells within the pack and the inhomogeneous cooling architecture. Another one can be the intrinsic variations between individual cells toward degradation sensitivity. These intrinsic variations have been documented in a few studies [1-2] but authors did not offer an elucidation of the underlying mechanism. In this presentation, we explore the nature and quantify the extent of the degradation discrepancies within a batch of commercial lithium-ion cells.
Results will be presented that distinguish performance mismatch down-the-road between kinetic origins (internal resistance build-up, degraded rate capability) and thermodynamic origins (loss of lithium inventory, loss of active material). In a limited previous study [3], we established a qualitative correlation between thermodynamic changes and kinetic properties of cycle-aged cells. In this more comprehensive study, we cycle-aged a larger number of single cells for more than 1,000 cycles to derive statistical correlations between these dual aspects of battery degradation.
Figure 1: Evolution of 15 cells capacities.
Returned capacity spread became very significant with cycling
References:
[1] Baumhöfer, T.; Brühl, M.; Rothgang, S. & Sauer, D. U., Journal of Power Sources , 2014, 247, p. 332
[2] Eom, S.W.; Kim, M.K.; Kim, I.J.; Moon, S.I.; Sun, Y.K. & Kim, H.S., Journal of Power Sources , 2007, 174, p. 954
[3] Devie, A.; Dubarry, M. & Liaw, B.Y., 224th ECS Meeting, Orlando, 2014

Figure 1
Ionic Liquid Based Electrolytes for High Temperature Lithium-Ion Batteries
Authors: Plylahan Nareerat , Kerner Manfred , Lim Du Hyun , Johansson Patrik 
Published: February 2020

Lithium-ion batteries (LIBs) have primarily been developed for application in portable devices, but during the past decade much attention has been paid on making progress also for electric vehicles (EVs). With this aim, elevated/high temperature (HT) operation and life-length is a critical issue, but HT is also an opportunity for simplified cooling systems (working at ca. 80-110ºC) and faster charge/discharge possible. Conventional organic electrolytes such as LiPF6 in EC:DEC is not a safe option due to high volatility and flammability, ultimately leading to the ease of catching fire, dangerous fumes, and possibly also explosions. Ionic liquid (IL) based electrolytes, on the other hand, are an interesting alternative for HT-LIBs owing to negligible vapor pressures, non-flammability, and high ionic conductivities.
In this work, we demonstrate that the IL Pyr13TFSI with an addition of LiTFSI is a potential electrolyte family for HT-LIBs. These electrolytes possess high thermal stability, up to 350°C, wide electrochemical stability windows, 0-5 V vs Li+/Li°, and ionic conductivities of the order of 10-3 S cm-1 at RT and 10-2 S cm-1 at HT (above 80°C). The LiTFSI0.2Pyr13TFSI0.8 electrolyte shows promising electrochemical stability in a LFP half-cell at 80°C delivering an average discharge capacity of 145 mAh g-1 at 1C (Fig.1). Additional doping of the IL based electrolytes with cyclic carbonates such as propylene carbonate (PC) and/or vinylene carbonate (VC), creating hybrid electrolytes, further improves the cycling performance in terms of capacity, stability and Coulombic efficiency. This is attributed mainly to a decrease in viscosity, leading to higher ionic conductivities and a better wetting of the electrode, and VC has the additional advantage of forming a stable SEI.
High Temperature Lithium-ion Batteries is a project funded by the Swedish Energy Agency and the collaboration between Chalmers University of Technology, Lund University, Uppsala University and Scania CV AB was created within the Swedish Hybrid Vehicle Centre.

Fig. 1 Specific capacity of LFP half-cells using IL based electrolytes cycled between 2.5 to 4.2 V vs Li+/Li° at 80°C and 1C rate. The open and closed circles represent the charge and discharge capacities, respectively.

Figure 1
Aluminium Rods As Current Collectors and Electrodes for 3D Li-Ion Micro-Batteries
Authors: Oltean Gabriel , Nyholm Leif , Edström Kristina 
Published: February 2020

The microelectronics industry has advanced at a rapid pace in the last decade. Further advancements are hampered by the lack of suitable on-board power devices. Although Li-ion batteries are the primary choice for energy storage, they cannot store enough energy per foot-print area without compromising power capability. Three-dimensional Li-ion batteries could offer the solution by using all three dimensions for efficient energy storage on a relatively small foot-print area.
Aluminium rods were obtained by template assisted galvanostatic deposition of aluminium into the pores of a commercial membrane. By the subsequent chemical dissolution of the membrane, free standing arrays of aluminium rods deposited on an aluminium substrate were obtained. It was shown that the use of a nucleation pulse prior to deposition led to a homogeneous deposition of aluminium rods, while the use of pulsed current rather than constant current resulted in a narrower distribution of the rods heights [1].
Aluminium is used as a current collector in Li-ion batteries. The deposition of TiO2 onto the aluminium rods was done by means of electrophoresis and a sol-gel derived impregnation method. While the electrophoretic deposition resulted in non-conformal coated rods, the impregnation method gave a thin amorphous deposit which could be cycled against lithium [2].
Finally, aluminium can be used as a negative active material, as it alloys with lithium. A study of the alloying and dealloying of lithium and aluminium was done on the 3D aluminium rods and a model for the lithiation and delithiation of aluminium has been proposed [3]. The aluminium rods were used as a negative electrode in a Li-ion battery against LiFePO4 coated on carbon foam positive electrode in a 3D cell with different geometries of the two electrodes [4].
References:
[1] G. Oltean, L. Nyholm, K. Edström, Electrochim. Acta, 56 (2011) 3203.
[2] G. Oltean, M. Valvo, L. Nyholm, K. Edström, Thin Solid Films, 562 (2014) 63.
[3] G. Oltean, C.-W. Tai, K. Edström, L. Nyholm, J. Power Sources, 269 (2014) 266.
[4] G. Oltean, H.D. Asfaw, L. Nyholm, K. Edström, ECS Electrochem. Lett, 3 (2014) A54.
Organic Vs. Inorganic Cations of Alkali-Metal Halide Containing Ionic Liquids for Sodium-Ion Battery Applications
Authors: Tucker Telpriore Gregory , Angell Charles Austen 
Published: February 2020

The power generation from either fossil fuels or preferably renewable energy sources is on the rise throughout the world. The pursuit of electrochemical devices for energy storage during peak power grid utilization is viable. There is great interest in further developing sodium batteries, particularly ZEBRA-type cells with chloroaluminate electrolytes. This lab has worked on understanding of weak-field, low-melting metal-halide based ionic liquids for use in the sodium-ion conducting batteries at a low-temperature of operation. This undertaking employed both organic and inorganic cations of low charge density, including the much-studied dialkylimidazolium cation. The vital issue of decreased ionic conductivity caused by alkali ion-trapping in these electrolytes, long known as a qualitative effect was recently quantified, discussed, and reported by us. We have since compared the conductivities of binary bromoaluminates in which large inorganic cations PBr4
+ formed by a bromide transfer process were used to replace the former dialkylimidazolium cation and here show the differences in the figure below. Currently, the electrochemical (along with other physical) properties are being characterized in preparations for testing in ZEBRA-type cells. This study leads to improved understanding of the factors determining electrolyte and electrochemical performance of sodium-containing binary electrolytes over a range of temperatures.
Figure: The top set of three conductivity isotherms are for [EMIM]AlCl4 - NaAlCl4 solutions, and the bottom set of three are for PBr4Al2Br7 - NaAl2Br7 solutions of varying molar fractions. The completely inorganic electrolyte requires 100oC (top blue line isotherm) to attain the ionic conductivity of the electrolyte containing the organic cation at 60oC (mid black line isotherm). We attribute the difference to incomplete bromide transfer in the formation of the large inorganic cation of the second system. The “alkali cation-trapping” effect probably remains in effect.

Figure 1