bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Formula Describing Impedance Artifacts Due to the Size and Surface Resistance of a Reference-Electrode Wire in a Thin-Film Cell
Authors: Verbrugge Mark W , Baker Daniel R , Hou Xu Xian
Published: February 2020

Reference electrodes are used in testing and designing thin-film cells in order to distinguish the effects of the positive and negative electrodes and determine the sources of significant resistance (or impedance), but the reference electrode introduces some distortion into the measurement due to non-uniformity of the current distribution. This often arises due to edge effects, the size and placement of the reference electrode, or both. Two common geometries for placing reference electrodes are internally, between the cathode and anode, and externally at a distance from the cathode and anode. Each design introduces some level of distortion, which must be clarified. This work focusses on internally-placed wire reference electrodes and elucidates the artifacts in cell impedance measurements as a function of wire size and wire surface resistance. Published simulations of impedance artifacts rely on computationally-intensive computer simulations, but we develop a simple formula to accurately approximate these effects. The formula is derived using a singular perturbation approximation to the impedance and then combining it with a simple equivalent circuit. Some comparisons with detailed numerical simulations show the accuracy of the resulting formula as a function of the diameter of the reference wire and its surface resistance.
A Combinatorial Approach to New Anode Materials for Aqueous Batteries
Authors: Marshak Michael P.
Published: February 2020

The synthesis and performance of new anode materials for aqueous batteries is described. These materials combine robust metal oxide electrode materials with organic materials based on anthraquinone (AQ) to vastly improve the energy and power densities and inhibit water splitting reactions. These amorphous materials are stable in aqueous electrolytes over a wide pH range, conductive, and can store as many as seven electrons per molecule. The organometallic anodes are currently being tested with nickel-oxide cathodes in alkaline conditions, lead-oxide cathodes in acidic conditions, and manganese-oxide cathodes in pH-neutral conditions, and show promise in producing a next-generation battery anode material for residential and commercial as well as grid-scale energy storage.
Computational Study on Oxidation Potential Variations of Electrolytes with Complexation in Lithium-Sulfur (Li/S) Batteries
Authors: Han Jaebeom , Balbuena Perla B
Published: February 2020

Lithium-sulfur (Li/S) batteries are attractive substitutes for current lithium-ion batteries (LIBs) because of the lower cost and higher theoretical capacity of the cathode materials compared to the current transition metal oxide cathode materials in LIBs. However, the polysulfide (PS) redox shuttle causes severe capacity fading of Li/S batteries during cycling, and a strong self-discharge behavior. Although there can be a lot of efforts to reduce or prevent the PS redox shuttle, the development of additives to cover the surface of the cathode is the most efficient way to resolve the PS redox shuttle in the Li/S battery. The passivation film generated by electrolyte additives can not only reduce the oxidation of electrolyte solvents on the surface of the sulfur cathode but also inhibit the dissolution of PS from the cathode into the electrolyte. Few studies have been carried out for this purpose in Li/S batteries even when there have been a variety of studies in LIBs for high-voltage cathode materials. In order to understand how surface films are generated, oxidation potentials and oxidative decomposed products should be studied first. In this study, the oxidation potentials of electrolyte solvents, Li salts, and additives are calculated using the density functional theory (DFT) with a continuum solvation model. Together with electrolyte solvents and Li salts in Li/S batteries, the mostly employed cathode passivation additives in Li-ion batteries and in Li/S batteries are investigated for additives. In addition, it is also investigated how oxidation potentials of these electrolyte systems are varied by complexations with Li+, anions of Li salts, and S8 and pyrene as model systems to mimic the sulfur-carbon electrode materials in Li/S batteries.
Combining Particle Tracking and Redox-Active Quinone Fluorescence within Porous Electrodes to Illuminate Local Mass Transport Properties of Aqueous Flow Batteries
Authors: Wong Andrew A. , Aziz Michael J. , Rubinstein Shmuel
Published: February 2020

As rapid advancements of novel redox flow battery (RFB) chemistries continue, increasing the performance of these electrolytes as they interact with the cell hardware remains a persistent challenge. Though chemical lifetime of aqueous organic RFBs is one figure of merit demanding attention, all RFB chemistries can benefit from a detailed understanding of mass transport and electrochemical activity within the stack components. In this study we use fluorescence microscopy to rapidly image fluid flow and electrochemical activity through a combination of tracer particles and redox-active soluble quinones. We use several techniques for mapping fluorescent tracer particle trajectories to evaluate fluid streamlines, local velocities and spatial heterogeneities. This information is then coupled with a spatial distribution of quinone fluorescence, which is used to determine local state of charge and rates of diffusion and advection. Consideration of regional mass transport is important for a comprehensive understanding of RFB performance; spatial heterogeneities in porous electrodes, which we observe over surprisingly large scales, can limit total flow battery performance due to higher mass transport overpotentials. Imaging experiments are designed in a bottom-up approach from a single wire to a full porous electrode, illuminating opportunities for rationally designed cell hardware to improve RFB performance for any chemistry.

Figure 1
Quinone-Based Aqueous Redox Flow Battery with Record Temporal Capacity Retention Rate
Authors: Lin Kaixiang , Kwabi David G. , Goulet Marc-Antoni , Kerr Emily , Pollack Daniel , Gordon Roy G. , Aziz Michael J.
Published: February 2020

The use of quinone/hydroquinone couples in aqueous redox flow batteries is a promising pathway toward cost-effective stationary electrical energy storage [1]-[4]. A major remaining challenge is long-term molecule stability. We previously reported a record capacity-retention rate in a flow battery utilizing substituted viologens and ferrocenes [5]; however, the open-circuit voltage was only about 0.7 V. Here we report a novel quinone-based aqueous redox flow battery with an open circuit voltage of 1.0 V and a capacity-retention rate that sets new records for cycling in the absence of rebalancing procedures. At the time this abstract is being submitted, capacity fade extrapolates to roughly 2%/year while cycling for days at approximately 110 cycles/day.

[1] B. Huskinson, M.P. Marshak, C. Suh, S. Er, M.R. Gerhardt, C.J. Galvin, X. Chen, A. Aspuru-Guzik, R.G. Gordon and M.J. Aziz, “A metal-free organic-inorganic aqueous flow battery”, Nature
505, 195 (2014).

[2] K. Lin, Q. Chen, M.R. Gerhardt, L. Tong, S.B. Kim, L. Eisenach, A.W. Valle, D. Hardee, R.G. Gordon, M.J. Aziz and M.P. Marshak, "Alkaline Quinone Flow Battery", Science
349, 1529 (2015).

[3] L. Hoober-Burkhardt, S. Krishnamoorthy, B. Yang, A. Murali, A. Nirmalchandar, G.K. Surya Prakash, and S.R. Narayanan, "A New Michael-Reaction-Resistant Benzoquinone for Aqueous Organic Redox Flow Batteries", Journal of the Electrochemical Society
164, A600 (2017).

[4] Z. Yang, L. Tong, D.P. Tabor, E.S. Beh, M.-A. Goulet, D. De Porcellinis, A. Aspuru-Guzik, R.G. Gordon, and M.J. Aziz, "Alkaline benzoquinone aqueous flow battery for large-scale storage of electrical energy” Advanced Energy Materials
7, in press (2017).

[5] E.S. Beh, D. De Porcellinis, R.L. Gracia, K.T. Xia, R.G. Gordon, and M.J. Aziz, "A Neutral pH Aqueous Organic–Organometallic Redox Flow Battery with Extremely High Capacity Retention", ACS Energy Letters
2, 639 (2017).
Thermal Power Generation with Use of Battery-Type Cell
Authors: Moritomo Yutaka , Shibata Takayuki , Fukuzumi Yuya , Kobayashi Wataru
Published: February 2020

The electrochemical thermoelectric coefficient (SEC =dV/dT; V and T are the redox potential and temperature, respectively) is a significant material parameter, because it enables us to convert thermal energy to electric energy. We demonstrate that a battery-type thermocell, which consists of two kinds of Prussian blue analogues (PBAs) with different SEC, produces electric energy during heat cycles. The Figure shows heat cycle of battery-type thermocell against cell voltage (Vcell) and temperature (T). The heat cycle consists of four processes: (i) heating from TL to TH , (ii) discharge at TH, (iii) cooling from TH to TL, and (vi) discharge at TL. The heating and cooling processes are performed without current (I = 0) The device produces electric energy of 2.3 meV/PBA par a heat cycle between 295 K (= TL) and 323 K (= TH). The thermal efficiency (= 1.0 %), which is evaluated with use of the heat capacity (C = 4.16 meV/K) of ideal Na2Co[Fe(CN)6], reaches 11 % of the Carnot efficiency (= 8.7 %). Our battery-type thermocell is a promising thermoelectric device that harvests waste heat near the room temperature.

Figure 1
Tin-Polyester/Polyimide Hybrid System As Flexible Free- Standing Film with Tunable Dielectric Constant for Energy Storage Application
Authors: Nasreen Shamima , Treich Gregory Martin , Tefferi Mattewos , Baczkowski Matthew Lucas , Anastasia Caroline , Cao Yang , Sotzing Gregory Allen
Published: February 2020

Hybrid free standing films of tin-polyester with polyimide are prepared by blending process which exhibit tunable dielectric constants. The maximum achievable dielectric constant for hybrid systems have 60% load of tin-polyester and their dielectric values raging from ca. 5.5-6.2, close to that of the tin homopolymers. These values show improvement over polyimide p(BTDA-HDA) having a dielectric constant of ca. 3.5 with minimum frequency dispersion maintaining low dissipation factor. The hybrid systems of 60% p(DMTDMG) with 40% polyimide stand out by their morphological and electrical properties showing a breakdown strength of 464 MV/m, with a maximum energy density of 5.9 J/cm3, slightly higher than the commercial standard BOPP with improved operational temperature ca. 140 oC.

Figure 1
Improving a Molten Carbonate Fuel Cell Matrix Strength By Fiber Reinforcing
Authors: Milewski Jaroslaw , Wejrzanowski Tomasz , Fung Kuan-Zong , Liu Bernard Hao-Chih , Szabłowski Łukasz , Baron Robert , Szczęśniak Arkadiusz , Tsai Shu-Yi , Ni Chung-Ta , Tang Jhih-Yu
Published: February 2020

Molten Carbonate Fuel Cell matrix which is made of LiAlO2 has tendence to cracking, which reduces the performance and durability of the MCFC due to electrolyte loss and gas crossover [1--5]. In this paper we propose testing different types of fibers in order to reduce the brittleness of the matrix during the start-up and operation of the MCFC. Reducing LiAlO2 matrix brittleness can be done the addition of ceramic fibers or by using highly porous ceramic paper infiltrated by LiAlO2.

Two types of LiAlO2 reinforcement are tested. The first---short fibers, and the second---high porous ceramic paper. Short fibers will be added to the slurry and the green tape will be obtained by the tape casting method. The second method will be based on infiltration of ceramic paper by LiAlO2 suspension.

Acknowledgments

The project is coefinanced by Polish National Center for

Research and Development of Polish-Taiwanese/Taiwanese-

Polish Joint Research Call granted by decision number DZP/

PL-TWIII/16/2016.

References

[1] Cheng, L. Guo, S. Xu, and R. Zhang: 2014: The Optimization of Matrix Preparation Process and Performance Testing for Molten Carbonate Fuel Cell, Journal of Chemistry 2014, 1-7, 2014.

[2] J.-E. Kim, K. Y. Patil, J. Han, S.-P. Yoon, S.-W. Nam, T.-H. Lim, S.-A. Hong, H. Kim, and H.-C. Lim: Using aluminum and Li2CO3 particles to reinforce the a-LiAlO2 matrix for molten carbonate fuel cells, International journal of hydrogen energy 34(22), 9227–9232, 2009.

[3] J.-J. Lee, H.-J. Choi, S.-H. Hyun, and H.-C. Im: Characteristics of aluminum reinforced g-LiAlO2 matrices for molten carbonate fuel cells, Journal of Power Sources 179(2), 504–510, 2008.

[4] H. Nirasawa, T. Kawachi, T. Ogawa, M. Hori, N. Tomimatsu, K. Nakagawa, H. Ohzu, and Y. Yamazaki: Stabilized matrix for molten carbonate fuel cell, Energy Conversion Engineering Conference, 1996. IECEC 96., Proceedings of the 31st Intersociety, Vol. 2, 1132–1137, 1996.

[5] K.Y. Patil, S. P. Yoon, J. Han, T.-H. Lim, S. W. Nam, and I.-H. Oh: The effect of lithium addition on aluminum-reinforced a-LiAlO2 matrices for molten carbonate fuel cells, International Journal of Hydrogen Energy 36(10), 6237–6247, 2011
Enhanced Li Metal Anode Stability By 3D Porous Nickel Substrate
Authors: Yu Lu , Canfield Nathan L , Chen Shuru , Lee Hongkyung , Engelhard Mark H , Li Qiuyan , Liu Jun , Xu Wu , Zhang Ji-Guang
Published: February 2020

Li metal anode is desirable for high energy density batteries because of its high theoretical specific capacity and lowest redox potential. However, its applications have been plagued for decades due to problems such as dendritic Li growth and low Li plating/stripping Coulombic efficiency (CE). The three-dimensional propagation of Li dendrites could penetrate the separator leading to safety concerns. In addition, Li dendrites could lead to dynamic breaking and forming of the solid-electrolyte interphase layer (SEI), causing fast electrolyte consumption and rapid capacity fading.

To address the above challenges, recently studies have demonstrated the effectiveness of 3D metal current collectors in suppressing Li dendrites and stabilizing the Li metal anode [1]. It has been suggested that the positive effect is mainly due to the high surface area of the 3D structure, which lowers the local current density and suppresses Li dendrites. Also the Li electrodeposits are accommodated inside the 3D current collector and this reduces the Li volume expansion. Although these reasons likely explain the benefits of using 3D current collectors, in-depth understanding of how 3D current collectors improve the SEI layer properties is not available. Gaining such knowledge is important for understanding the fundamental mechanism and designing effective 3D current collectors to stabilize Li metal anode.

In this study, we investigated the fundamental mechanism by which a 3D porous Ni current collector improves Li metal anode stability. Using a combination of galvanostatic intermittent titration technique and scanning electron microscopy, it was found that the 3D porous Ni current collector can effectively suppress the “dead” Li formation and forms a compact and robust surface layer. This surface layer protects Li metal and Li ion transport through this layer is unimpeded over cycling. However, without the 3D porous Ni current collector, significant amount of “dead” Li is accumulated on the Li metal over cycling, which leads to mass transport limitations. X-ray photoelectron spectroscopy results further revealed the differences in the SEI layer composition on the Li metal embedded in porous 3D Ni substrate and the 2D Li metal substrate.

1. S. S. Chi, Y. Liu, W. L. Song, L. Z. Fan and Q. Zhang, Adv. Func. Mater., 27, 1700348 (2017).
Rechargeable Zinc-Ion Batteries Based on Deep Eutectic Solvent
Authors: Kao-Ian Wathanyu , Kheawhom Soorathep
Published: February 2020

The intermittent characteristic of renewable energy sources leads to a significant challenge in energy generation. Considerable efforts have been made to explore viable solutions, with rechargeable batteries standing out among various energy storage systems. Recently, lithium-ion batteries (LIBs) are widely used in various energy storage devices. However, the high cost, inherent safety risks, and limited lithium resources seem to restrict their large-scale application. Therefore, different new rechargeable battery systems such as aluminum-ion, magnesium-ion, and zinc-ion batteries (ZIBs) have been developed. Among these, rechargeable ZIBs with high safety, abundant electrode materials, high theoretical capacity, environmentally benignity, and low-cost, have received extensive attention.

Typically, a ZIB system consists of a host material capable of storing zinc ions as the cathode, zinc metal as the anode. The cathode material becomes the primary limitation for battery performance and manganese dioxide (MnO2) is considered the most promising candidate due to its natural abundance, environmental benignity and low-cost. Generally, mild aqueous electrolyte made of sodium sulfate (Na2SO4) solution are implemented. However, the narrow electrochemical stability window of aqueous electrolytes has limited the operating voltage of the host materials. Thus, deep eutectic solvents are introduced to address this issue. Nevertheless, the mechanism of zinc ion storage and the reason for the capacity fading in ZIB system in deep eutectic solvents have not been thoroughly clarified.

In this work, we present a rechargeable ZIB that is composed of a zinc anode prepared from nickel foam supported zinc, a cathode made of stainless steel mesh supported MnO2/carbon film and an electrolyte made of a non-flammable deep eutectic solvent (ethylene glycol/(2-hydroxyethyl) trimethylammonium chloride). ZnCl2 additive in the electrolyte was examined, and the optimal ratio of ZnCl2 was determined. The fabricated battery operated through the electrochemical deposition and dissolution of zinc at the anode, and intercalation/de-intercalation of zinc ions in the MnO2 structure. The fabricated battery exhibited a large capacity of about 200 mAhg-1 and a charge efficiency of approximately 98%. The cathode was found to withstand more than 2,000 cycles without significant capacity decay. The results demonstrated a deep eutectic solvent-based ZIB and offered a fundamental basis for understanding the electrochemical intercalation chemistry of zinc ions in a deep eutectic solvent.

Figure 1
Water-Lubricated Intercalation in V2O5·nH2o for High-Capacity and High-Rate Aqueous Rechargeable Zinc Batteries
Authors: Yan Mengyu , He Pan , Mai Liqiang , Yang Jihui
Published: February 2020

Low cost, environmentally friendly aqueous Zn batteries have great potential for large-scale energy storage. In our previous work, we found that the intercalation of zinc ions in the cathode materials is challenging and complex [1, 2]. In this talk, we will try to clarify it by showing the critical role of structural H2O on Zn2+ intercalation into the V2O5 framework [3].

Our latest results demonstrate that the H2O solvation of Zn2+ largely reduces its effective charge and thus its electrostatic interactions with the V2O5 framework, effectively promoting the diffusion of solvated Zn2+. Benefited from the ‘lubricating’ effect, the aqueous Zn battery shows a specific energy of ~ 144 Wh kg-1 at 0.3 A g-1. Meanwhile, it can maintain an energy density of 90 Wh kg-1 at a high power density of 6.4 kW kg-1
(based on the cathode and 200% Zn anode), making it a promising candidate for high-performance, low-cost, safe, and environmentally friendly energy storage device. Such a ‘lubricating’ effect in Zn batteries could be applicable to other multivalent metal ion-based batteries for further improving the energy storage performance, and could also shed light on discovering new battery materials.

Reference

[1] H. Pan, Y. Shao, P. Yan, Y. Cheng, K. S. Han, Z. Nie, C. Wang, J. Yang, X. Li, P. Bhattacharya, Nature Energy
2016, 1, 16039.

[2] P. He, M. Yan, G. Zhang, R. Sun, L. Chen, Q. An, L. Mai, Advanced Energy Materials
2017, 7.

[3] M. Yan, P. He, Y. Chen, S. Wang, Q. Wei, K. Zhao, X. Xu, Q. An, Y. Shuang, Y. Shao, K. T. Mueller, L. Mai, J. Liu, J. Yang, Advanced Materials, 1703725, doi: 10.1002/adma.201703725.
Transition Metal Segregation and Phase Transformations on the Surfaces of Layered Li(Ni1-x-yMnxCoy)O2 (NMC) Cathode Materials for Li-Ion Batteries
Authors: Garcia Juan , Han Binghong , Key Baris , Vaughey John T. , Dogan Fulya , Iddir Hakim
Published: February 2020

Nickel-rich layered oxide cathode materials have seen widespread deployment due to their high gravimetric capacity and high average discharge voltage. However, achieving this high capacity requires charging voltages above the potential at which the electrolytes decompose at the cathode surface (>4.5 V vs. Li/Li+), which leads to impedance rise and capacity loss. Furthermore, the reduction of the transition metals and oxygen loss produces a phase transformation that might be detrimental to the electrochemical performance. One strategy to stabilize this interface and improve the cycling of cathode materials is by the use of a surface coating. In this talk, we present recent Density Functional Theory (DFT) efforts aimed at gaining insights on the processes occurring at the cathode surfaces and the effect of alumina coating. It will be shown that Ni and Co possess distinctive roles in the formation of surface segregation layers (SRLs) on Li(Ni1-x-yMnxCoy)O2 NMCs. The results show that Al prefers to be surrounded by Co and Ni cations in the transition metal layers of NMC structures. The existence of Mn in the transition metal layer can therefore hinder the intercalation of Al from the surface to the bulk of the NMC particles. A discussion on the thermodynamics that govern such processes will be given.

The authors gratefully acknowledge support from the U. S. Department of Energy (DOE), Vehicle Technologies Office. Computer time allocations at the Argonne's Laboratory Computing Resource Center, is gratefully acknowledged. This research also used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Argonne National Laboratory is operated for DOE Office of Science by UChicago Argonne, LLC, under contract number DE-AC02-06CH11357.

The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
Low Frequency Piezoelectric Energy Harvesters Based on Pb-Free Thin Films
Authors: Kim Da Bin , Oh Hyo Chan , Han Chan Su , Cho Yong Soo
Published: February 2020

The successful utilization of Pb-free piezoelectric materials for the most useful cantilever-type energy-harvesters has been a critical interest for better performance. Here, we introduce the piezoelectric energy-harvesting characteristics of Bi0.5Na0.5TiO3-BaTiO3 (BNT-BT) thin films. The BNT-based thin films have not been reported so far for the energy-harvesting applications. 0.94BNT-0.06BT thin films, which are in the morphotropic phase boundary, showed the best dielectric and piezoelectric performance. The poling effect on the 0.94BNT-0.06BT thin films was also investigated by varying poling electric field, poling temperature and poling time. The 0.94BNT-0.06BT with poling process showed the improved piezoelectric constant of 3.13 C/m2 in the poling condition of 700 kV/cm, 60 oC and 20 min, compared to that of 3.04 C/m2 for films without poling process. XRD patterns showed the increased intensity of (002) peak indicating the increase in the volume fraction of the c-domain of BNT-BT film by applied external electric field, and thus the figure of merit (FOM) values were improved with increased poling field. As a result, the cantilever type energy harvester showed the output power of 2.22 µW from the vibration source with 42 Hz.
Effect of Zr Substitution for Ti on BaZrxTi1−XO3 Thin Films for Energy Storage Applications
Authors: Instan Alvaro A , Pavunny Shojan Pullockaran , Bhattarai Mohan K , Katiyar Ram S
Published: February 2020

Recently, energy storage capacitors research attention turned towards lead-free and eco-friendly dielectric BaTiO3. Many efforts have been made to improve the dielectric properties of the BTO thin film capacitors. Barium titanate is one of the most studied ferroelectric materials because they possess high permittivity, polarization and piezoelectric properties, low dielectric loss and high dielectric breakdown field and it is very attractive for many applications. With this motivation, highly oriented thin films of BaZrxTi1−xO3 (BZT) with different concentrations of Zr were fabricated on LSMO/MgO(100) substrates to compare their energy storage performances while varying Zr concentration in Pt/BZT/LSMO/MgO(100) heterostructures. Deposition of BZT layers were done at an oxygen partial pressure of ∼150 mTorr. During laser ablation of BZT at a laser energy 250 mJ on the target, substrate temperature was maintained at 650 °C using an excimer laser operating at a pulse frequency of 10 Hz. Thickness of the thin films was precisely maintained by controlling the number of laser shots. These thin films was analyzed by x-ray diffractometry and Raman spectroscopy. Studies on structural phase transition, ferroelectric, dielectric, leakage current, and energy-storage properties revealed the applicability of these thin film structures in future integrated high energy density capacitors. We will present the aforementioned properties of these thin films and will discuss the intended energy storage applications of this dielectric material in detail.
Room-Temperature, Ambient-Pressure Chemical Synthesis of Amine-Functionalized Hierarchical Carbon-Sulfur Composites for Lithium-Sulfur Battery Cathodes
Authors: Chae Changju , Kim Ju Young , Choi Youngmin , Jeong Sunho
Published: February 2020

Recently, the achievement of newly designed carbon-sulfur composite materials has attracted a tremendous amount of attention as high-performance cathode materials for lithium-sulfur batteries. To date, sulfur materials have been generally synthesized by a sublimation technique in sealed containers. This is a well-developed technique for the synthesizing of well-ordered sulfur materials, but it is limited when used to scale up synthetic procedures for practical applications. In this study, we suggest an easily scalable, room-temperature/ambient-pressure chemical pathway for the synthesis of highly functioning cathode materials using electrostatically assembled, amine-terminated carbon materials. It is demonstrated that stable cycling performance outcomes are achievable with a capacity of 727 mAh/g at a current density of 1 C with good cycling stability by a virtue of the characteristic chemical/physical properties (a high conductivity for efficient charge conduction and the presence of a number of amine groups that can interact with sulfur atoms during electrochemical reactions) of composite materials. The critical roles of conductive carbon moieties and amine functional groups inside composite materials are clarified with combinatorial analyses by X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy.
Toward a Dendrite Free, Powder Compact-Based Solid Electrolyte Lithium Metal Battery: Interfacial Modification
Authors: Zhao Ran , Gebhardt Ryan , Whale Alison , Hu Guantai , Martin Steve W
Published: February 2020

Owing to its high energy density and light weight, Li-ion batteries have taken away over half of the worldwide rechargeable battery market. However, the safety issues of Li-ion batteries that originate from the combustible organic electrolyte are of great concern recently. Solid-state batteries using powder compact solid electrolytes (PCSE) are promising options toward safer and higher energy density batteries due to the utilization of inorganic electrolyte and metal lithium as anode, however, the high solid-solid interfacial resistance between the lithium metal and the solid electrolyte is still a challenge.

In this work, we demonstrate reversible plating and stripping of dendrite-free metallic-lithium with a reduced anode/PCSE interfacial resistance by introducing a thin interfacial layer formed by heating. First, the PCSE which has an ionic conductivity of ~ 10-4 S/cm at room temperature, was synthesized by mechanical milling, and characterized using NMR, DSC, IR spectroscopy, and Raman spectroscopy. Next, the PCSE was tested in symmetric cells for electrochemical impedance spectroscopy and cycling. To address the high solid-solid interfacial resistance and short-circuiting dendrite problems, we demonstrate a simple strategy to engineer the lithium-PCSE interface by forming an in-situ interlayer via a heat treatment. The area specific resistance of 573.6 Ω/cm2 has been successfully achieved with a 0.9 mm thickness pellet under a current density of 0.1 mA/cm2. These results provide a promising PCSE membrane that can be applied to lithium metal battery and other energy storage application, such as lithium sulfur batteries.
An Examination of the Factors That Influence Primary Battery Longevity Performance Under Multiple-Cell Vs Single-Cell Testing Conditions
Authors: Joubert Jessica , Iveson Ray
Published: February 2020

Primary alkaline batteries still account for the vast majority of battery sales in the US. According to the test standards of the American National Standards Institute (ANSI), primary alkaline cell longevity performance is intended to be measured by discharging individual cells under specific load and duty cycle conditions to prescribed cutoff voltages. However, market research studies indicate that greater than 90% of battery-driven devices in the US require more than 1 cell, in electronic series configuration, to function. Thus, the analysis of primary alkaline battery performance in multiple-cell configuration will yield results that are far closer to the battery performance observed in actual devices and, therefore, is more consumer relevant. Focusing on AA size batteries, multiple cells discharged in series configuration demonstrated consistently lower cell performance (measured in service hours) vs single cells discharged under similar load and duty cycle conditions. The magnitude of decrease in performance for any battery design was highly related to the performance variability exhibited in single cell performance testing. Additional factors that influenced the lower performance observed in multiple-cell testing included the number of cells in series, discharge load magnitude, load type, endpoint voltage and battery design characteristics such as rate of increase of polarization during discharge. The relative importance of these factors to multiple-cell performance was quantified along with consideration of the deficiencies of reporting primary battery performance based on single-cell performance testing.
Advanced Cycle Life Model Based on 18650 Lithium-Ion Battery Cells
Authors: Park Joonam , Byun Seoungwoo , Park Jinkyu , Appiah Williams Agyei , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Lithium-ion batteries (LiBs) have already become main energy storage devices for a variety of applications such as cellular phones, laptops, electric vehicles (EVs), and energy storage systems (ESSs). Because they have not only high energy density but also long cycle life performance with low self-discharging behaviour. Furthermore, the market size of EVs and ESSs is also expected to grow up exponentially in the near future. So, it is strongly required to estimate or predict long-term cycle life of LIBs under various operating conditions. However, due to time and facility limitation, it is almost impossible to confirm cycle lives for longer than 10 years and at various temperatures. That is why accelerated life testing methods and computation modeling have been spotlighted immensely. In particular, there have been reported various battery models, however, most of them did not show high accuracy to predict long-term electrochemical performance owing to the lack of in-depth analysis of LIB cells.

Hence, we attempt to build an advanced cycle life model based on physicochemical analysis data during cycling. First, hundreds of 18650 LIB cells are cycled at different c-rates, temperature, and depth-of-discharge, and their degradation behaviour will be gathered. And then, based on Newman’s works, the degradation equations about solid electrolyte interphase(SEI) growth and crack on the anode, an electrolyte depletion, and cathode electrolyte interphase(CEI) growth on the cathode, will be built and applied to this model.
Synthesis of Ternary Nico-MnO2 Nanocomposite and Its Application As a Novel High Energy Supercapattery Device
Authors: Oyedotun Kabir Oyeniran , Madito Moshawe , Momodu Damilola , Mirghni Abdulmajid , Masikhwa Tshifhiwa , Manyala Ncholu
Published: February 2020

NiCo /NiCoMn-mixed hydroxides and ternary NiCo-MnO2 electrode materials were successfully synthesised by a force-driven hydrolysis of hydrated nickel, cobalt and manganese nitrate salts at 40 °C for 2 h with an additional annealing step adopted in producing the NiCo-MnO2 sample. The morphological, structural, compositional and textural characterization of the samples were obtained using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and N2 physisorption respectively. The initial sample characterization confirmed bigger material agglomeration of the as-prepared mixed hydroxides compared to the NiCo-MnO2 sample which had small stacked sheet-like and porous morphology. Further sample analysis also confirmed a high degree of crystallinity in both the mixed hydroxides and NiCo-MnO2 samples with the elemental constituents existing in different oxidation states. One of the mixed hydroxides sample namely, NiCo(OH)2 exhibited a specific surface area (SSA) of approximately 3.40 m2 g-1 as compared to the ternary NiCo-MnO2 material which exhibited a higher SSA of 153.94 m2 g-1. The ternary NiCo-MnO2 electrode exhibited the highest specific capacity of 132.1 mAh g-1, compared to NiCo(OH)2 and NiCoMn-triple hydroxide (NiCoMn-TH) electrodes which exhibited a specific capacities of 110.3 and 64.36 mAh g-1 respectively at a current density of 0.5 A g-1. In addition, the ternary NiCo-MnO2 electrode exhibited a better cycling stability compared to NiCo(OH)2 electrode. Notably, an assembled NiCo-MnO2//C-FP hybrid asymmetric supercapattery, displayed a specific capacitance of 130.67 F g-1, high energy and power densities of 48.83 Wh kg-1 and 896.88 W kg-1 at 1 A g-1 respectively. An excellent cycling stability with a coulombic efficiency of 99.98% and capacitance retention of 96.78 % was recorded for up to 10,000 cycles within an operating voltage of 1.5 V, at a 3 A g-1 current density.
A Three-Dimensional N/Co-Doped Macroporous Carbon Interweaving with Carbon Nanotubes As Excellent Bifunctional Catalysts for Zn-Air Batteries
Authors: Guo Wei
Published: February 2020

Highly efficient noble metal-free bifunctional catalysts for expediting the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in metal-air batteries or fuel cells are still challenging and imperative. In this work, we report a facile and scalable method for syntheizing three dimensional (3D) N/Co co-doped macroporous carbon interconnecting with in-situ growth carbon nanotubes (CNTs). The as-synthesized material exhibits great electrocatalytic performance for ORR with an onset potential of 0.901V vs.RHE as well as high limited current density of 4.83 mA/cm2 in alkaline electrolyte under a rotation speed of 1600 rpm at 5 mV/s. Furthermore, this 3D porous carbon also shows good electrocatalytic performance for OER in alkaline electrolyte. This high electrocatalytic performance is mianly attributed to its large specific surface area, high conductive CNTs and synergistic effect between Co active species and carbon framework. The result of a two-electrode Zn-air battery based on this carbon material achieves a peak density of 163 mW/cm2 at the voltage of 0.63 vindicates the great potential of the catalyst for battery application.
Probing Electrochemical Structure-Property Relationships at Non-Porous Monolayer Electrodes of Exfoliated Graphene and MoS2 Single Layers
Authors: Walker Wesley R , Xu Luzhu , Krysiak Olga A , Pope Michael A
Published: February 2020

The electrochemically available surface area and porosity of 2D materials is difficult to control due to the strong aggregation and restacking phenomena that occur when single layers are processed into thin or thick film electrodes. Furthermore, the distributed resistance, the potential for pore-size related effects and the uncertainty in relating estimated surface area and porosity data to the actual electrochemically accessible surface area make measurements of the intrinsic electrochemical performance of these materials difficult to assess. Ideally, electrochemical measurements are carried out on flat, polished or atomically flat electrode surfaces for the evaluation of intrinsic double-layer capacitance and electrochemical rate constants.

In this talk, we will discuss our efforts to create large-area monolayers of solution exfoliated 2D materials for electrochemical evaluation in aqueous and non-aqueous electrolytes. Using a modified Langmuir-Blodgett technique, we demonstrate the ability to create uniform and large area monolayers of graphene oxide, thermally reduced graphene oxide as well as 1T and 2H molybdenum disulfide which can be transferred to atomically flat electrode substrates such as highly oriented pyrolytic graphite. These films are found to be stable during electrochemical cycling in various electrolytes and allow us to probe electrochemical properties as a function of 2D material structure without porosity-related artifacts.

This model system has been used to probe the changes in double-layer capacitance in both aqueous and non-aqueous electrolytes for graphene-based materials as a function of defect density. It has allowed us to estimate the theoretical limits of graphene-based supercapacitors as a function of graphene “type”. More recently, this analysis has been extended to probe the intrinsic capacitance of the metallic 1T and semiconducting 2H polymorphs of MoS2 as a function of layer number to probe the charging mechanisms at play. The system also offers the ability to probe the capacitance of graphene/MoS2 heterostructures. These and future studies are expected to provide valuable insight into how we might build more energy dense supercapacitors from the optimal combination of 2D materials.
(Invited) Experimental Synthesis of 2D Borophene
Authors: Guisinger Nathan P
Published: February 2020

The recent experimental discovery of borophene, the metallic 2-dimensional allotrope of boron, has sparked tremendous interest in further exploration of this unique material. The initial synthesis of borophene was accomplished on Ag substrates and serves as a quintessential example of predictive modeling to experimental realization. In this talk, we expand the phase-space of borophene synthesis to Au. Borophene synthesis was accomplished by evaporating elemental boron onto a Au(111) substrate. The synthesized borophene retains its metallic character on Au as verified with scanning tunneling spectroscopy. Most fascinating is the difference in growth dynamics on the Au(111) substrate where the reconstructed surface presents a unique energy landscape for borophene nucleation and growth. We find that the initial low-coverage growth of borophene modifies the herringbone reconstruction into a “trigonal” network, where the 2D boron islands are uniformly templated across the surface. Increasing coverage results in the increasing size of the templated borophene islands until they coalesce into larger sheets. The observed growth dynamics are supported by the computational modeling of boron nucleation on Au.
Exfoliated Vanadium Dichalcogenides (VS2, VSe2, VTe2) By Lithium Intercalation Exhibit Dramatically Different Properties from Their Bulk Counterparts
Authors: Wang Yong , Sofer Zdeněk , Luxa Jan , Pumera Martin
Published: February 2020

Layered transition metal dichalcogenides (TMDs) have been attracting great interest due to their excellent electrical, optical, and electrochemical properties they exhibit when exfoliated down to mono- or a few-layer material. Driven by the unique properties, numerous methods have been developed to isolate few-layered TMDs. In this study, lithium intercalation route which is initially established for MoS2 and WS2 has been adopted to exfoliate the vanadium dichalcogenides (VS2, VSe2, and VTe2). Following the inherent electrochemical properties of these bulk and exfoliated vanadium dichalcogenides were studied along with their potential as electrocatalysts towards hydrogen evolution reaction (HER). This lithium intercalation method leads to the different degree of exfoliation following the VS2 > VSe2 > VTe2 order. Besides, upon exfoliation to single/few layer VX2 become partly converted to nonstoichiometric vanadium oxide and lithium vanadates, which is strikingly different when compared to group 6 TMDs, such as MoX2 and WX2. Inherent electrochemical results indicate that both bulk and exfoliated VS2, VSe2, and VTe2 possess inherent electrochemical activity, which can limit their application for electrocatalysts and electrode materials. HER performance study of bulk and exfoliated vanadium dichalcogenides shows that the presence of vanadium oxides and lithium vanadates formed during the exfoliation process can highly influence the HER performance.
Flexible Graphite a Novel Platform for SERS Detection and Outstanding EMI Shielding
Authors: Sykam Nagaraju , Jayram Naidu Dhanpal , Mohan Rao G
Published: February 2020

Exfoliated graphite (EG) has paying global consideration in the last decade because of the growing number of potential applications of these materials. So far, the production of EG based on binary or ternary compounds as intercalation and oxidation agents has been studied. However, the method consumes more quantity of acid, more number of compounds, time and energy. Here, we report a simple low cost one compound based rapid and efficient production of EG using microwave irradiation technique about 1min. The compressed form of EG without addition of any binder called flexible graphite sheet (FGS). As fabricated FGS shows outstanding Surface Enhanced Raman spectroscopy (SERS) detection as well as electromagnetic interference (EMI) shielding. FGS demonstrates responsive SERS for R6G molecules up to detection limit of 10-7 mol/L without any nanoparticle incorporation. The total electromagnetic interference (EMI) shielding effectiveness (SET) of – (96-84) dB was observed for FGS in the frequency region of 5-12GHz. These are the highest reported values for both (EMI shielding and detection) based on single material till today.

Keywords: Exfoliated graphite, Flexible Graphite sheet, Microwave irradiation, EMI shielding and SERS.
Conductivity Mapping in Graphene through Scattering-Type Scanning Near-Field Optical Microscopy in the Mid-Infrared and Terahertz Spectral Region with 25nm Spatial Resolution
Authors: Hartmann Nicolai F. , Gokus Tobias , Eisele Max , Huber Andreas J.
Published: February 2020

Terahertz (THz) imaging and spectroscopy has emerged as a powerful tool for analysis of biological specimens or for studying and controlling low-energy excitations in solid-state systems [1]. One major limitation of THz spectroscopy is, however, the spatial resolution that is limited by diffraction to about 100-1000 µm, making it impossible to extract intrinsic, local material characteristics of nanoscale Graphene or other 2D-material structures or devices.

Scattering-type scanning near-field optical microscopy (s-SNOM) bypasses the diffraction limit, enabling optical measurements with extreme sub-wavelength spatial resolution of below 20 nm [2]. THz time-domain s-SNOM spectroscopy of a semiconductor static random access memory (SRAM) sample enables quantitative analysis of free carrier concentration and scattering rates of nanoscale device structures at unprecedented surface sensitivity. Similarly, THz s-SNOM measurements at single frequencies enabled highlighting highly conductive nanostructures in transistor devices [3]. Using a similar experimental concept to generate a local photo-current by THz radiation allows for studying nanoscale conductivity in a biased graphene device [4] or to characterize carrier scattering in a graphene sheet that has been encapsulated in hexagonal boron nitride (h-BN) and placed on a split metallic film [5].

Using an SRAM sample as a method to calibrate the amplitude contrast of the s-SNOM THz measurement with known free carrier concentrations the concept is extended to graphene. Single to few layer graphene on h-BN is imaged with a broadband THz pulse and reveals changing amplitude contrast independently of layer number (Fig. (a), (b), zoom in (d)). In a corresponding s-SNOM measurement carried out at 10 µm an inverted contrast can be observed (Fig. (c)). This contrast inversion is a direct consequence of the scattering frequency dependent free carrier response in graphene [6].

Extending the already established concepts of mid-IR s-SNOM imaging and spectroscopy of 2D materials [7] to the THz frequency range a plethora of fundamental and applied new insights into graphene and other 2D device structures can be expected from THz near-field nanoscopy measurements.

[1] M. Tonouchi, Nat. Photonics
2007, 1, 97; [2] F. Keilmann, R. Hillenbrand, Phil. Trans. R. Soc. Lond. A
2004, 362, 787; [3] A. J. Huber et al. Nano Lett.
2008, 8, 3766; [4] P. Alonso-Gonzalez, et al., Nat. Nanotechnol. 2016, 12, 31; [5] B. Lundeberg, et al., Science
2017, 357, 187; [6] J. Horng et al., Phys. Rev. B
2011, 83, 165113; [7] D. N. Basov et al., Science
2016, 354, 1992.

Figure 1
(Invited) 2D Nanosheet Optics and (Opto-)Electronics
Authors: Mueller Thomas
Published: February 2020

The materials that have enabled the information technology revolution over the past decades will soon reach their physical limits. Novel nanomaterials and technologies have therefore become a major focus of current solid-state device research, with two-dimensional (2D) atomic crystals being one of the most promising candidates. Graphene, a 2D structure of carbon atoms with unorthodox electronic properties, is the most prominent representative of the 2D material family. More recently, transition metal dichalcogenides (TMDs) have come into the focus of interest, as these offer properties that complement those of graphene. Some TMDs are semiconductors with a sizable bandgap, which allows the construction of logic transistors, light emitters, photovoltaic solar cells, and other devices. In the first part of this talk, I will preset some of our spectroscopic studies on linear and nonlinear optical properties of 2D semiconductors, including polarization-resolved second harmonic measurements that show strain-induced modifications of the second harmonic pattern, and single photon emission from localized exciton states. I will then review our activities on photovoltaic energy conversion, photon detection and electrically driven light emission in TMDs. Finally, the development of electronic circuits based on 2D materials will be discussed. Large-area MoS2 monolayer-film growth by chemical vapor deposition, together with the development of 2D logic stages, enabled us to realize the first large-scale digital integrated circuit based on a 2D material. It is envisioned that the excellent material quality, combined with the advantages of 2D materials, such as flexibility, high mechanical stability and low costs of production, could lead to new electronic and optoelectronic technologies.