bluuebunny/crossref_metadata_2025 huggingface dataset:
New Electrolyte Composition for High-Voltage Lithium-Ion Cathodes – Enhancing the Cycling Stability in Half- and Full-Cells
Authors: Kazzazi Arefeh , Bresser Dominic , Kuenzel Matthias , Kim Guk-Tae , Passerini Stefano
Published: February 2020

The steadily rising utilization of lithium-ion batteries for large-scale applications, in particular, electric vehicles requires the development of cell chemistries that offer increased energy and power densities.1,2 Essentially, there are two options to enhance the energy density: Increasing the capacity of the employed active materials and/or elevating the full-cell voltage by switching to high-voltage cathode materials. The latter, however, face the great challenge to identify a suitable electrolyte composition, as commonly used organic carbonate-based electrolyte are not sufficiently stable towards oxidation. To avoid the resulting detrimental side reactions, the use of electrolyte additives is easily implementable into common cell manufacturing technologies and, thus, very cost-efficient.3,4 For such reason, a plethora of electrolyte additives has been reported in recent years, but frequently these additives have been proven only to enhance the performance for selected cathode materials, while particularly the evaluation with graphite-based anodes has been commonly overlooked.

Herein, we report on a new electrolyte composition, incorporating functional electrolyte additives for high-voltage cathode materials like LiNi0.5Mn1.5O4 or 5V-olivines, which moreover reveal a beneficial impact also for graphite-based anodes and, consequently, also in lithium-ion full-cells. As a result, lithium-ion half- and full-cells with a cell voltage of >4.5 V show a greatly enhanced cycling stability, increased capacities, and improved efficiencies.

References

B. Scrosati, J. Hassoun, and Y.-K. Sun, Energy Environ. Sci., 4, 3287 (2011).

D. Bresser et al., J. Power Sources, accepted manuscript (2018).

S. S. Zhang, J. Power Sources, 162, 1379–1394 (2006).

J. Kalhoff, G. G. Eshetu, D. Bresser, and S. Passerini, ChemSusChem, 8, 2154–2175 (2015).
A Study on Cathode Interface of Li-La-Zr-O Solid-State Electrolyte Fabricated Via Rapid Sintering Process
Authors: Yang Hwichul , Lee HoJae , Kim Sunmin , Christy Maria , Kim Young-Beom
Published: February 2020

For recent lithium-ion batteries (LIBs), there have been lots of researches about convert liquid-phase electrolyte to solid-state electrolyte (i. e. all-solid-state battery) to improve safety and stability. Solid-state electrolyte materials have to satisfy some criteria including high ionic conductivity at room-temperature, chemical stability against reducing environment, and mechanical strength. Many solid-materials for electrolyte have been researched, including perovskite, garnet, and sulfide-type of materials. Among them, garnet-type based lithium lanthanum zirconium oxide (LLZO, Li7La3Zr2O12) has been received attention due to its high ionic conductivity (~10-4 S/cm at room temperature) and wide electrochemical stability window (~6 V versus Li/Li+). The main issue of LLZO is the high interfacial resistance with anode and cathode materials such as Li metal and LiCoO2. Many researchers have tried to understand the cause of this interfacial resistance for LLZO. K. Park et al. researched about the cathode/electrolyte (LLZO) interface and revealed co-diffusion and second-phase formation of LLZO at high-temperature [1]. M. Zarabian et al. reported that spin-coated LLZO on the LiCoO2 pellet fabricated at low-temperature (~400oC) and co-diffusion of La and Co at the interface by using X-ray photoelectron spectroscopy (XPS) [2]. They commonly suggested that elevated temperature make chemical interaction and this make high interfacial resistance.

In this study, we adopted novel sintering method, flash light annealing (FLA) process, to fabricate LLZO solid-electrolyte. This method is also called rapid, cool sintering because of its unique characteristics compared to conventional sintering methods [3]. FLA uses instantaneous high current to generate intensive pulsed light (IPL), and irradiate IPL toward the specimen to sinter the materials. Unlike the conventional sintering methods, this novel method has lots of advantages including availability of treatment at STP and fast sintering time (~ a few ms). Rapid sintering process gives no time for the diffusion at the interface, thus the interfacial resistance between cathode and LLZO solid-electrolyte must be reduced. We fabricated LLZO solid-electrolyte on the commercial LiCoO2 pellet by using solution-based spin-coating method and sintered the film by using FLA method. XPS and energy-dispersive X-ray spectroscopy (EDX) analysis were conducted to observe interface and diffusion of La and Co elements. Also, X-ray diffraction (XRD) method was used to investigate sintering ability of FLA through crystallinity development. The interfacial resistance between LiCoO2 and LLZO solid-electrolyte was analyzed by electrochemical impedance spectroscopy (EIS) through cross-plane set-up.
(Invited) Present Status and Future R&D Needs for Batteries for Vehicle and Grid Applications
Authors: Srinivasan Venkat
Published: February 2020

Electrochemical energy storage (i.e., batteries) is an enabling technology that holds the key to transitioning from fossil fuels for our vehicle needs and managing the intermittency of renewables on the grid. Over the last 5 years, numerous electric vehicles have entered the market and storage technologies are being deployed on various grid applications. These changes are mainly driven by innovations in lithium-ion batteries, both in materials and in manufacturing, that have resulted in the cost of the technology decreasing at a steady pace. This cost reduction is expected to accelerate in the near future, by leveraging economies of scale (e.g., Tesla’s recently announced Gigafactory) and vertical integration. However, despite these exciting changes, more is needed to ensure widespread deployment of electrified vehicles and stationary storage for grid-connected applications. Further decreases in cost, increase in cycle/calendar life and energy density, and significant improvement in safety will remain challenges. Advances in battery technology, ranging from incremental improvements to Li-ion technologies, “beyond” Li-ion concepts, and lower-cost technologies for grid storage, including flow batteries, are needed to enable an electrified future.

This talk will summarize the present status of battery technology for vehicle and grid applications and provide a gap analysis between the present status and the requirements. The talk will also describe the efforts now underway to bridge the gap, both in development of new technologies and in manufacturing of these systems with an eye on reduction in cost. Using techno-economic modeling efforts at ANL and elsewhere, we will summarize the prospects of Li-ion, Li-metal (including Li-air and Li-S), Mg-ion based systems, and flow batteries compared to the requirements.
(Invited) First-Principles Approaches to Modeling Electrochemical Interfaces Validated By X-Ray Spectroscopy
Authors: Prendergast David
Published: February 2020

In our attempts to understand and control the activity at electrochemical interfaces, first-principles calculations based on density functional theory prove invaluable in providing atomistic descriptions of such interfacial chemistry. Furthermore, recent advances in X-ray spectroscopy enable in situ examination of working cells with both interfacial and chemical sensitivity. Interpretation of such measurements benefits greatly from exploration of possible chemistry at reactive surfaces and direct simulation of spectra based on molecular dynamics sampling. We combine insight from continuum modeling of electrolytes next to charged electrodes with first-principles determinations of free-energy profiles of electrolyte species at specific electrode surfaces. In this way, we aim to have models consistent with thermodynamic boundary conditions at charged interfaces. We provide examples relevant to chemically reactive electrodes, and elucidation of speciation in the electric double layer, which can inspire strategies to enhance performance in new electrochemical systems or simply increase our understanding of atomic scale mechanisms behind electrochemical processes.
(Invited) Force-Responsive Hydrogel Made of Block Polyrotaxane
Authors: Maeda Rina , Masayuki Taniguchi , Uenuma Shuntaro , Mayumi Koichi , Yokoyama Hideaki , Ito Kohzo
Published: February 2020

Stimuli-responsive polymers that are sensitive to certain triggers from the external environment have been attracting many researchers’ interests. Stimulus that can be used to trigger these materials have been varied from temperature, light, electrical or magnetic fields, to chemicals. However, some applications require new triggers such as force. We thought that polyrotaxane-based gel is a new candidate of force-responsive material. Polyrotaxane is a type of mechanically interlocked supramolecule consisting of polymer axle and ring molecules, in which multiple rings are threaded onto a polymer axle and prevented from dethreading by bulky end groups. When a force is applied to polyrotaxane gels, in which polyrotaxanes are crosslinked through ring molecules, ring molecules slide along an axle polymer to evenly distribute the applied force. Recently we created block polyrotaxane whose axle is a triblock copolymer poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-PPO-PEO).[1] β-Cyclodextrin (β-CD) form inclusion complex with PPO but not with PEO in water. We hypothesized that chemical property of the hydrogels obtained from this block polyrotaxane would be converted to hydrophobic by force. β-CDs should stay on PPO segment without loading, while β-CDs would slide from PPO to PEO segment to expose hydrophobic PPO segment when a force is applied. In order to confirm this concept, we studied hydrogels based on polyrotaxane made of β-CDs and PEO-PPO-PEO with several molecular weight and PEO/PPO ratio. Three polyrotaxanes compared in this study are followings; PEO60-PPO30-PEO60 with 17CDs (PPR_7k), PEO80-PPO70-PEO80 with 13CDs (PPR_11k), PEO110-PPO55-PEO110 with 12CDs (PPR_13k) (subscripts denote a number of repeating unit of each segment). 1H NMR measurements were conducted to investigate a position of β-CDs of a series of polyrotaxanes in water. It was found that β-CDs in the PPR_13k shuttles both on PEO and PPO segment but β-CDs in PR_7k and PR_11k stayed on PPO. Small-angle X-ray scattering (SAXS) was conducted to the hydrogels obtained from cross-linked polyrotaxane. Figure shows SAXS 1D profiles of the hydrogel obtained from PPR_11k. Before stretching, no peak was observed based on a periodic structure. Then this hydrogel was extended to 1.8 times of the original state to show a peak corresponding to a periodic distance of 29 nm. These results indicate PPO segments were exposed after loading to form hydrophobic periodic domains in PPR_11k. Other hydrogels obtained from PPR_7k and PPR_13k did not show any periodic structures even after loading. We are hoping that this new force-responsive block polyrotaxane system can be applied to the materials that can alter materials permeability by an applied force.

[1] S. Uenuma et al.
Chem. lett., 45 (8), 991-993 (2016)

Figure 1
(Plenary) Slide-Ring Materials: Novel Molecular Concept for SHINAYAKA Polymers
Authors: Ito Kohzo
Published: February 2020

We have recently developed a novel type of polymer network called slide-ring materials by cross-linking polyrotaxane, the supramolecular architecture with topological characteristics. In the network, polymer chains are topologically interlocked by figure-of-eight cross-links. Hence, these cross-links can pass along the polymer chains freely to equalize the tension of the threading polymer chains similarly to pulleys. The structure and physical properties of the polymeric materials are drastically different from conventional cross-linked or noncross-linked materials. For instance, the slide-ring gel or elastomer shows quite small Young’s modulus, which is not proportional to the cross-linking density and much lower than those of chemical gels with the same density. This arises from the difference in the molecular mechanism of the entropic elasticity: While the conformational entropy is mainly responsible for the elasticity in usual chemical gels or rubbers, the mechanical properties of the slide-ring gel should be inherently governed by the alignment entropy of free cyclic molecules in polyrotaxane as well as the conformational entropy of backbone polymer. This means that the softness in the slide-ring gel is due to the novel entropic elasticity, which is also expected to yield sliding state and sliding transition. Consequently, the slide-ring materials have the dynamic coupling between two kinds of entropy: the conformational entropy of strings and alignment entropy of rings. 2,3) The concept of the slide-ring gel is not limited to cross-linked gels but also includes elastomer, cross-linked polymeric materials without solvent. Accordingly it can be applied to wide area such as soft contact lens, paints, rubbers, soft actuator and so on. As a typical example, the scratch-resist properties of the self-restoring slide-ring elastomer were adopted into the top coating on the mobile phone.4) Finally, I would like to introduce ImPACT (Impulsing Paradigm Change through Disruptive Technologies) program, which is promoting to create flexible and tough polymers by using the slide-ring materials as a key technology.
A Photoresponsive Polymeric Actuator Topologically Cross-Linked by Movable Rings Based on a [2]Rotaxane Structure
Authors: Osaki Motofumi , Takashima Yoshinori , Yamaguchi Hiroyasu , Harada Akira
Published: February 2020

A photoresponsive polymeric material, in which [2]rotaxane units with α-cyclodextrin (αCD) threading onto an azobenzene (Azo) derivative is used as a topological cross-link for the main chains of the polymeric material in aqueous media, was achieved.

As shown in Figure 1a, A polycondensation reaction between Lys-αCD/Am2Azo inclusion complex and Su2PEG gave polymeric material cross-linked by [2]rotaxane (αCD-Azo hydrogel). [2]Rotaxane structures in the αCD-Azo hydrogel were found to act as movable links in the polymer network, and the mechanical properties of the material were enhanced to show a rupture strain of 2800%. The materials were reversibly deformed by irradiation with UV or visible lights in aqueous media, which caused photoisomerization of the azobenzene moiety and changed the structure of the [2]rotaxane linker, leading to deformation of the polymer network (Figure 1b).

Surprisingly, the dry material (αCD-Azo xerogel), which had been uniaxially extended in air, showed a faster response than the αCD-Azo hydrogel. The orientation of the polymeric network in the materials enables the efficient response. As shown in Figure 1c, the αCD-Azo xerogel quickly bent towards the light source side within 3 seconds upon irradiation with UV light. 5.6 mg of the αCD-Azo xerogel also performed 5.6 μJ of mechanical work within 10 seconds by the UV-irradiation, which is approximately 50 times higher than that achieved in our previous work1.

Figure 1.
The preparation of the αCD-Azo hydrogel as a topological material (a), schematic illustration of the αCD-Azo hydrogel before and afeter the irradiation with UV (b), and lateral views of the αCD-Azo xerogel showing deformations driven by UV irradiation.

[1]. Iwaso, K.; Takashima, Y.; Harada, A. Nat. Chem.
2016, 8, 625-632.

Figure 1
Development of Ion Conductive Monolithic Polymers
Authors: Ahmed Kumkum , Naga Naofumi , Furukawa Hidemitsu
Published: February 2020

Polymer monoliths composed with macroporous sizes are one of the potential candidates in separation technology and for efficient and stable separators in batteries and fuel cells [1]. Recently, thiol-ene "click" reaction has been received extensive attention in the field of monolith preparation owing to its exceptional versatility and propensity for the quantitative conversions under mild conditions along with extending the choice of versatile categories of functional monomers. In this work we report a wide variety of joint-linker type porous polymers induced by phase separation during polymerization, by utilizing thiol-ene reaction of multi-functional thiol, 1,3,4-Tris(3-mercaptobutyloxethyl)-1,3,5-triazine-2,4,6- (1H,3H,5H)-trione (3T), pentaerythritol tetrakis(3-mercaptobutylate) (PTMB) etc. as the joint molecules, and poly (ethylene glycol) diacrylate-1000 (PEGDA-1000) as the linker molecules in ethanol. Ion conducting phenomenon of these monoliths has been introduced by swelling them in a wide variety of Ionic liquids (IL). We have studied the concentration effect of joint molecules and temperature on the physical features of these monolith polymers. These microporous monoliths exhibited diverse mechanical prosperities and morphology. In contrary to ionic gels [3] the monolithic structure with entrapped ILs exhibited high ionic conductivity due to the loosely bound ions within the porous polymer network. Physical properties of these IL entrapped monoliths have been investigated to optimize suitable IL-monolith combination for best performance in application of separator membranes for batteries and for separation technology.

References

Sakakibara, K., Kagata, H., Ishizuka, N., Sato, T., Tsujii, Y. Fabrication of surface skinless membranes of epoxy resin-based mesoporous monoliths toward advanced separators for lithium ion batteries. J. Mater. Chem. A, 5, 6866–6873 (2017).

Liu, Z., Ou, J., Zou, H., Click polymerization for preparation of monolithic columns for liquid chromatography. Trends Anal. Chem., 82, 89–99 (2016).

Ahmed, K., Naga, N., Kawakami, M. & Furukawa, H. Development of ionic gels using thiol-based monomers in ionic liquid. 9800, 980005 (2016).
(Invited) Bioinspired Materials that can Sense and Adapt to Mechanical Loadings and Damages
Authors: Orrego Santiago , Krekora Urszula , Kang Eugene , Hou Decheng , Kang Sung Hoon
Published: February 2020

Nature provides numerous examples of advanced materials with remarkable properties. Inspired by natural systems, there have been active efforts to understand design principles of natural materials and to synthesize bioinspired materials with outstanding properties. We have been inspired by natural structural materials with outstanding mechanical properties such as bone, coral reef, and wood that can adapt to their surrounding environment. For instance, bone can control mineral quantity proportional to the amount of stress from its sensing and mineral synthesis control mechanism. It becomes stronger in locations subjected to the higher mechanical loads, and vice versa. This leads to the formation of mechanically efficient structures for optimal biomechanical and energy-efficient performance.

However, it has been a challenge for making synthetic materials that sense change of loading conditions and damage and change their structures and properties to adapt to new conditions. Moreover, materials degrade over time due to fatigue and damages accelerate the degradation rate, resulting in reduction in the lifetime of the materials and increase of the maintenance costs. If materials can repair damages, we can have more efficient use of materials with reduced associated costs. Synthesizing materials that can sense and adapt to mechanical loading and repair damages, can help us to use materials for a broad range of loading conditions with extended lifetime and reduced costs.

To address the challenge, we are inspired by previous findings that bones are formed by mineralization of organic scaffolds using ions from blood. We report a material system that triggers mineral synthesis from simulated body fluids onto organic scaffolds upon mechanical loadings and/or damages so that the material can modulate its mechanical properties to adapt to loadings and regenerate upon damages. For example, we observed ~40% increase in the modulus of the material upon periodic loadings for 3 days. We also observed that the material could self-repair damages generated by removing ~5 μm thick minerals from the matrix, in 7 days. In addition, we demonstrate a simple way of making functionally graded material based on stress distribution within a material that results in graded deposition of minerals. We envision that our findings can open new strategies for making synthetic materials with self-adaptable mechanical properties and self-repair capability as well as tuning material properties on-demand.
Effect of H2 Evolution in Aqueous Aluminum Air Battery
Authors: Zhou Chong , Bhonge Kaustubh , Cho Kyu Taek
Published: February 2020

The demand of electrical energy system is increasing rapidly these days for diverse applications from portable electronics and electrical vehicles to grid-scale energy storage. Lithium-ion battery has been utilized for most of those applications, but due to high cost (about $600/ kWh) and lower energy density (0.38 kWh/kg) [1], the advent of low cost and high performing battery system is required. Metal-air system, which has metal as a reactant for the anode side and oxygen for the cathode side of the battery cell, is getting intense attention due to its benefits such as high energy density and low system cost. Especially, metals such as lithium, aluminum, magnesium, calcium, iron, and zinc whose reduction potential is substantially low are typically used for the negative electrode, while oxygen generally from air is used for the positive side.

The energy density of the metal-air battery systems is 3 to 10 times greater than that of the conventional lithium ion battery (i.e. specific energy of the metal-air system is in the range from 0.8 to 3.9 kWh/kg, while that of the conventional lithium ion battery is 0.38 kWh/kg) [2].

Especially, aluminum of which specific energy is roughly 10 times greater than lithium ion battery is abundant, low price, environmentally benign, and inertness to humid operating condition, preventing the catastrophic thermal failure which is the major safety issue of the conventional system. However those promising systems could not be fully utilized due to the challenging issue associated with the redox reaction of metal electrode: self-corrosion reaction (i.e. hydrogen evolution)[3].

In this study, the effect of H2 evolution due to aluminum corrosion on the cell performance will be investigated through combined research of experiment (cell-based and component-based tests) and physics-based computational model. Especially, the coverage of H2 bubbles on the electrode surface, change of diffusion layer thickness affected by the H2 bubble rise, and change in the electrolyte conductivity will be analyzed with respect to various pH conditions, flow rate conditions, and currents. The results will be utilized to understand the underlying physics of H2 bubble issues and to define the key controlling parameters for the cell performance.

Reference

[1] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J.-M. Tarascon, Nat Mater 2012, 11, 19-29.

[2] Q. Li, N. J. Bjerrum, J. Power Sources 2002, 110, 1-10.

[3] D. R. Egan, C. Ponce de León, R. Stokes, F. C. Walsh, J. Power Sources 2013, 236, 293-310.
Efficient Third-Party Abstraction of Lithium-Ion Batteries for Asset Modeling
Authors: Rogall Martin , Greenwood David , Barai Anup , Bhagat Rohit , Luk Patrick , Brucoli Maria
Published: February 2020

As part of international strategies towards high penetration of renewable energy sources, the implementation of energy storage systems in power grids becomes increasingly necessary for short- and long-term energy deferral. Due to technical advantages in short-term and overall practical advantages, Lithium-Ion batteries are excellent storage mediums and already serve today widespread in a variety of applications both stationary and mobile.

However, most storage systems are privately funded. To investors, battery storage is considered an asset with high capital expenditure and slow, only partially predictable return on investment. The value estimation of storage systems is intercepted by two major difficulties. The first issue is the inherent complexity of batteries regarding performance and aging, which requires in-depth knowledge for accurate statements. The second issue is the inability to determine the optimal operation strategy due to the sizable portfolio of potential applications, reaching from frequency response over arbitrage to peak-shaving, and the potential impact of each on the storage system.

Investors are commonly provided with very few details on the battery itself and don’t always have the background knowledge necessary to accurately predict battery behavior and value generation in long term due to this complexity. This makes battery storage less tangible and less attractive than other assets.

This presentation introduces a tool for potential customers of battery storage that can be applied to any market-available carbon-based Li-Ion battery technology. It aims to provide an approximation for the battery’s lifetime behavior based on a multi-physics model. Electrical, thermal and aging models are constructed from literature and scaled and enhanced through experimental data.

The tool, which is developed in Python, takes as input the maximum amount of information available to customers in advance while making the minimum amount of assumptions about the storage system. The tool produces an approximation for the degradation of the storage system on an absolute and linear scale and can therefore be used inside optimization algorithms or as pre-processing tool. It is designed to be easily transferable and computationally efficient enough to allow for flexible parameter adjustment and multi-case comparison between storage providers and applications on any scale.

Figure 1
Performance and Stability of Cathode Electrode Under Carbon Capture Operating Conditions
Authors: Hilmi Abdelkader , Geary Timothy C , Franco Adam , Yuh Chao-Yi
Published: February 2020

Introduction

The high-temperature molten carbonate fuel cell (MCFC) is one of the most advanced clean power generating devices. To date >8 billion kWh of clean electricity has been produced commercially using this new technology. The high operating temperature of MCFC (550-650°C) dramatically improves the reaction kinetics and eliminates the need for a noble metal catalyst. The electrochemical reactions taking place during cell operation involve CO2 transfer from cathode to anode through electrolyte matrix in the form of carbonate ions (Figure 1). The transport of CO3
= is equivalent to that of O= and CO2 (CO3
= ⇔ O= + CO2). Therefore, MCFC stack technology can be utilized for efficient simultaneous power generation and CO2 separation/capture by integrating with conventional combustion-based coal and/or natural-gas power plants.

The state of the art MCFC cathode is porous lithiated NiO. The cathode performance and stability are affected by several factors such as gas composition, temperature, electrode structure, and electrolyte chemistry. To ensure long-term performance and material stability (such as NiO cathode dissolution, polarization loss and CO2 capture efficiency), material selection, operating characteristics, and electrode design need to be carefully considered.

FCE has operated numerous bench-scale single cells (100 W) and technology stacks (30 kW) under carbon capture operating conditions (4-5% CO2 in the cathode inlet as opposed to >15% in baseline MCFC systems) to understand parameters affecting performance, life, and to investigate design solutions for further enhancement. Figure 2 shows similar NiO cathode stability under standard as well as carbon capture conditions, projecting to useful life of >7-years under both operation conditions. More endurance carbon capture tests are being conducted for further verification.

This paper will review the cathode material stability, microstructure, and durability under long-term carbon-capture operations. The effect of parameters such as electrolyte fill, gas composition and electrolyte chemistry, as well as approaches to enhance the CO2 capture efficiency and life, will be discussed.

Figure 1
Real-Time Imaging Analysis on Dendrite Formation of Aluminium Metal Anodes
Authors: Liu Hao-Wen , Wu Nae-Lih , Huang Hsiao-Wen , Chiang Chien-Chih , Yang Chang-Chung
Published: February 2020

In recent years, rechargeable batteries are one of the most attractive options for both grid electrical energy storage and electrical vehicle (EV) applications due to the steadily increasing demands. Aluminum is the most abundant metal in the earth’s crust. Rechargeable aluminum-ion batteries (AIBs) is a promising research for future energy storage technologies due to its impressive advantages such as high anode capacity (gravimetric capacity of 2980 mAh g−1, and volumetric capacity of 8040 mAh cm−3), cost effectiveness, and safety. A recent study reported by Dai et al. cooperate with ITRI opened a new stage for this topic by employing an AlCl3/[EMIm]Cl ionic liquid electrolyte and graphitic cathode. This pioneering work has been stimulating various research enthusiasms in aluminum-ion batteries (AIBs).

At present, there are multiple challenges that need to be overcome in AIBs, including, for example, decomposition of the electrolyte material, small charge-discharge voltage window of the battery, and small energy/power densities, (compared with commercially available lithium batteries). The occurrence of aluminum dendrites, which could cause safety hazards, on the other hand, has not drawn sufficient attention.

In this study, we studied in real-time using optical microscopy the occurrence of dendritic aluminum electrochemical plating and its dendrite formation mechanisms. In particular, extensive real-time optical microscopy imaging and post mortem SEM analyses are carried out in conjunction with electrochemical characterizations to reveal the underlying mechanisms for the resulting effects.

Figure 1
Electrochemical Performance Enhancement of Na0.7MnO2 for Sodium-Ion Batteries By Doping and Conformal Surface Coating
Authors: Yu Han , Liang Xinhua
Published: February 2020

Sodium-ion batteries (SIBs), which have similar working mechanism to that of Li-ion batteries (LIBs), have attracted great attention as new power sources for large-scale energy storage because of the abundant of Na reserves. However, there is still a huge challenge for the development of SIBs due to the low rate capacity and poor cycle stability of cathode materials. Different approaches of element doping and surface modifications have been widely applied to improve the electrochemical performance of those cathode materials. Herein, doping of Ti4+ and Zr4+ and coating of TiO2 and ZrO2 have been achieved by atomic layer deposition (ALD). The rate capability and cycling stability of the modified material were improved and the enhancement mechanism was studied. The TiO2 and ZrO2 coatings act as a stable interfacial layer to enhance the cycle stability of NMO by suppressing side reactions between the electrode and electrolyte. The doping of transition metal ions reduces the bond length of Mn-O and increases its bond energy, which further enhances the stability of the layered structure. In addition, the doping of transition metal ions can also enhance the intrinsic electronic conductivity by enlarging the Na-O bond length and lowering the Na+ migration barrier, thereby increasing the rate capacity.
Modeling the Electrical and Thermal Behaviors of a Lithium-Ion Battery Under External Short Circuit Conditions
Authors: Cho Jaesung , Koo Boram , Shin Chee Burm , Ha Yoon-Cheol
Published: February 2020

The lithium-ion battery (LIB) is the primary choice for many applications such as mobile electronics, electric vehicles, and stationary energy storage solutions due to its high energy density, high voltage and low self-discharge rate. Reported safety incidents related to LIBs have resulted in an increased attention toward the safety issue of the LIB. In the operation of LIBs, there are many sorts of field failures including overheat, overcharge, and short circuit. External short circuit (ESC) is a severe fault which causes the large current flow and high temperature rise in an LIB immediately. Modeling to predict the maximum current flow and temperature rise of an LIB under ESC fault is essential to design an effective fault detection and diagnosis system for the safety management of LIB.

In this work, a modeling is performed to predict the electrical and thermal behaviors of an LIB cell under ESC conditions. The validation of the modeling approach is provided through the comparison of the modeling results for a 75Ah LIB cell from KOKAM with the experimental measurement data obtained from the ESC tests. The ESC tests were carried out using the external resistances of 0, 2, and 5 mΩ. Model predictions reasonably reproduce the experimental data.
Development of MWCNT/α-MnO2/MoS2 Ternary Composite for High-Performance Supercapacitor Application
Authors: Rajagopal Rajesh , Ryu Kwang-Sun
Published: February 2020

Development of MWCNT/α-MnO2/MoS2 ternary composite is presented in this work as an electrode material for supercapacitor application. MWCNT/α-MnO2/MoS2 ternary composite was synthesized by facile hydrothermal method. The structural details of MoS2, α-MnO2/MoS2 and MWCNT/α-MnO2/MoS2 ternary composite were studied by powder X-ray diffraction technique and nitrogen adsorption analysis. The surface morphology of the synthesized materials was analyzed by field emission electron microscope technique and the elemental analysis was carried out using EDS analysis. High-resolution transmission electron microscope analysis revealed the detailed surface analysis of MWCNT/α-MnO2/MoS2 ternary composite. The active material was mixed with a polymeric binder and drop coasted on the nickel surface and the electrochemical performances of the active material were elucidated from cyclic voltammetry, charge-discharge, and electrochemical impedance spectroscopy techniques. We observed a linear relation between the square root of the scan rate and peak current, which were confirmed the diffusion controlled ion transportation. The specific capacitance values of prepared MoS2, α-MnO2/MoS2, and MWCNT/α-MnO2/MoS2 ternary composite were calculated from charge-discharge technique at a various applied current density (1 to 5 A g-1) in 1 M Na2SO4 aqueous electrolyte. We found that the synthesized MWCNT/α-MnO2/MoS2 ternary composite electrode exhibits higher specific capacitance value than MoS2, and α-MnO2/MoS2 electrodes. Further, the resistive and capacitive behavior of the electrodes was studied from Nyquist and bode diagrams within the frequency range of 10 mHz to 100 kHz.
Application of the Maximum Power Point Tracking (MPPT) Algorithm on Lithium-Ion Batteries
Authors: Shrestha Sujan , Dion Matt , Sholin Mark
Published: February 2020

This work focuses on the application of the maximum power point tracking (MPPT) algorithm to discharge lithium-ion batteries at their maximum possible power. This algorithm is routinely applied in photovoltaic applications but has only seen limited application in battery applications so far.

A simple form of the MPPT algorithm is used in this work. A fixed magnitude of current is applied, and the new value of power is calculated. If the new value of power is greater than the previous one, the current is varied in the same direction until the maximum power is reached. This algorithm is simple to implement and consumes low computing power. However, the magnitude of a current step should be optimized. If the current step is very small, the time taken to reach the maximum power will be too long. And if the current step is very large, there will be a large oscillation near the power maxima.

Therefore, we study the effect of current steps during application of the MPPT algorithm on lithium-ion batteries. Comparative studies between various optimization methods such as gradient descent, steepest descent and Newton’s method are made. The effect of discharging batteries at their maximum power on their life cycle is also investigated.

The information obtained from this study can be a useful guide to designing a battery management system that gets the maximum performance out of a lithium-ion battery.

References

Selvan, P. Nair and Umayal, “A review of photovoltaic MPPT algorithms,” International Journal of Electrical and Computer Engineering, 6, 2016, 567-582.

A. B. Vieira and A. M. Mota, “Maximum power point tracker applied in batteries charging with PV panels,” 2008 IEEE International Symposium on Industrial Electronics, Cambridge, 2008, 202-207.

Kim, S. Mohan, J. B. Siegal and A. G. Stefanopoulou, “Maximum power estimation of lithium-ion batteries accounting for thermal and electrical constraints,” Proceedings of the ASME 2013 Dynamic Systems and Control Conference, California, 2013.
Microstructured Electrodes Supported on Serpentine Interconnects for Stretchable Electronics
Authors: Nasreldin Mohamed
Published: February 2020

In this work, we report the fabrication of lithium nickel manganese oxide (LNMO) micropillar electrodes on Al serpentine interconnects that can be stretched up to 70% without structural damaging. Unlike compact and continuous electrode thin-films, we show that under mechanical strains, arrays of vertical micropillar supported on serpentines are carrying empty spaces that can prevent the formation of cracks and the electrode delamination. This innovative approach opens interesting perspectives for the fabrication of truly stretchable devices including Li-ion microbatteries, solar cells, transistors, sensors, etc.
A High-Performance Polymer Electrolyte Membrane Enhanced By Graphene Oxide Doped By Redox Species
Authors: Zhou Xiangyang , Yan Zhiwei , Wang Yuchen , Zhang Chen , Qiao Xiaoyao , Mansour Azzam N. , Waller Gordon H. , Martin Curtis , Du Zhijia
Published: February 2020

A high-performance electrolyte membrane was synthesized by combining poly (vinylidene fluoride)/Lithium bis(trifluoromethanesulfonyl)imide (PVDF)/LITFSI electrolyte with graphene oxide (GO), and the lithium salt of tungstosilicic acid (SiWLi). The impact of the addition of GO/SiWLi on the microstructure, crystallinity, and morphology were characterized by Fourier transform infrared spectra (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that homogeneously distributed GO contributed to a reduction of the pore size and crystallinity of polymer electrolyte membrane. The addition of GO/SiWLi to a conventional polymer electrolyte membrane not only resulted in an increased ionic conductivity from 0.93x10-2 S cm-1 to 3.12x10-2 S cm-1, but also an increased lithium ion transference number from 0.549 to 0.895. The membranes with and without GO/SiWLi were used to fabricate planar all solid-state supercapacitors (SCs) and Li-ion batteries. The all-solid-state SCs fabricated with the membrane containing GO/SiWLi displayed a much lower internal resistance than those fabricated with the membrane without GO/SiWLi. As a result of the reduced resistance, the specific capacitance of the SCs with the membrane containing GO/SiWLi was 30% greater than that of the SCs without GO/SiWLi. When evaluated in a Li-ion battery configuration, the high-performance electrolyte membrane led to a two-fold increase in the achievable capacity utilizing galvanostatic conditions ranging from a 5 C-rate to 20 C-rate.
Sputtered Iridium Oxide Microsupercapacitors Operating in Physiological Electrolytes
Authors: Maeng Jimin , Geramifard Negar , Chakraborty Bitan , Cogan Stuart F.
Published: February 2020

Implantable devices (e.g. biosensors, neural prosthetics) are increasingly an option for the prevention, diagnosis, and treatment of human diseases and disorders, leading to patient rehabilitation and health improvement. Such devices are typically powered by an external source through wires or an internal battery. Unfortunately, these conventional power sources pose challenges and concerns; while wires are primary sources of infection and patient discomfort, implanted batteries pose safety concerns and suffer from the need for periodic replacements that involve a surgery which is an additional risk. Therefore, there is a need for an alternative power source that safely operates in human body with sustained durability.

Supercapacitors are a class of electrochemical energy storage devices that may complement or even replace the implanted batteries. Besides the favorable traits of supercapacitors, including high power density, rapid charging and discharging, and long cycle life, the major advantage of supercapacitors particularly towards implantable applications lies in the possibility for directly utilizing physiological fluid as a source of electrolyte. This makes it unnecessary to house additional electrolyte in a package and thus precludes toxic electrochemical reactions associated with battery electrolytes. Such a package-free configuration also enables significant miniaturization of supercapacitors and may open up a possibility for implantation into previously unexplored body organs such as blood vessel, eyeball, or bladder.

Here, we present sputtered iridium oxide microsupercapacitors operating in physiological electrolytes as progress toward human-body implantable energy storage devices. Supercapacitors having micropatterned interdigital electrodes coated with sputtered iridium oxide films are fabricated and characterized in two types of physiological electrolytes: a phosphate-buffered saline (PBS) solution and an inorganic model of interstitial fluid (model-ISF) that mimics the body fluid more closely. These devices exhibit a maximum volumetric capacitance density of 342 F cm-3, an energy density of 47.5 mWh cm-3, and a power density of 40.5 W cm-3 in PBS. It is observed that 55-74% of these values are still available in model-ISF. The energy and power density values obtained here are higher than those for other reported microsupercapacitors characterized in conventional aqueous or solid-state electrolytes. The devices maintain a proportional increase in current density from a scan rate of 20 to 200 mV s-1 and retain 40% of the initial voltage against a self-discharging for 6 hours. They also exhibit a capacitance retention of 100% under 10000 charge-discharge cycles at a scan rate of 200 mV s-1. The demonstrated energy storage performance and the durability in the physiological electrolytes warrant investigation of the proposed microsupercapacitors in biological fluids toward human-body energy storage applications.
Redox-Mediated Bromate Based Electrochemical Energy System
Authors: Cho Kyu Taek , Razaulla Talha
Published: February 2020

A promising redox-mediated bromate-ion (BrO3
-) based system was investigated through research combined with mathematical modeling and full-cell test to understand the characteristic effect of electrochemical reaction coupled with chemical reaction on the cell behaviors. This system has a unique feature of the reaction mechanism in which the reactant (Br2) is not provided externally, but is kept regenerated by a coupled chemical reaction of bromate in the cell, which may lead to “no limiting current” condition (i.e. non-zero concentration of the reactant species at the electrode surface for any current conditions) by eliminating mass transfer (i.e. concentration) over-potential, and thus this system is estimated to achieve the ultra-high performance [1-4].

From the full-cell based test, a unique behavior induced by this auto-catalytic reaction was found for the first time, and to understand the underlying physics and nature of the system, theoretical study was conducted through mathematical modeling and analytic analysis.

Three reaction mechanisms (E, EC, and EC’) were compared in their characteristic reaction behaviors to understand the nature of each reaction mechanism, and the results were analyzed with respect to reaction time and species concentration at the electrode surface. Furthermore, the effect of actual condition of bromate system (i.e. non-unity stoichiometry and limited amount of bromate) was analyzed at unsteady condition for the first time to understand its characteristic behavior in the actual battery condition.

As a final step, the effect of catalytic reaction was analyzed analytically to define the parameters to control the catalytic reaction, and especially, the effect of relative rate of electrochemical reaction and coupled chemical reaction on the autocatalytic reaction was compared through a zone diagram where conditions for pure diffusion controlled and pure kinetic controlled cases were defined.

References

[1] Y. Tolmachev, A. Piatkivskyi, V. Ryzhov, D. Konev, M. Vorotyntsev , J Solid State Electrochem, 19 (2015) 2711-2722.

[2] M.A. Vorotyntsev, A.E. Antipov, Y.V. Tolmachev, Electrochimica Acta, 222 (2016) 1555-1561.

[3] M.A. Vorotyntsev, A.E. Antipov, Journal of Electroanalytical Chemistry, 779 (2016) 146-155.

[4] M.A. Vorotyntsev, A.E. Antipov, Electrochimica Acta, 258 (2017) 544-553.
(Invited) Graphitization of Carbon Obtained from Local Biomass (babassu) and Their Electrochemical Properties
Authors: Ghosh Anupama , Razzino Claudia do Amaral , Dasgupta Archi , Fujisawa Kazunori , Cunha Jose , Lobo Anderson Oliveira , Robinson Joshua , Terrones Mauricio , Viana Bartolomeu Cruz
Published: February 2020

Activated Carbon obtained from babassu mesocarp was heat - treated at different temperatures. Samples were submitted to heat treatment at 1100°C, 1400°C and 2200°C and they were designated as AC-1100, AC-1400 and AC - 2200, respectively. At 2200°C, AC was graphitized, which was confirmed by Raman, TEM and XRD. In the Raman spectra besides the D', D'', D and G bands, two amorphous bands were observed. It was possible to observe that the intensities of amorphous bands decrease with heat treatment and in AC - 2200 disappear completely. D'+ D, 2D and D + G bands were almost inseparable and with very low intensity in the samples AC, AC-1100 and AC-1400 but in AC - 2200, the 2D band was very intense. At the temperature 2200 ºC, AC have graphitic behavior which has been confirmed by Raman, TEM and XRD characterizations. Furhermore, The cyclic voltammetry and electrochemical impedance spectroscopy measurements were performed. The AC-1400 presents highest double layer capacitance and a great surface area. In contrast, the AC-2200 exhibit a capacitance value of 95-fold smaller than AC-1400. Both are excellent electrodes for applications that require high surface area. The AC-1400 electrode presents high capacitance and can be used as an electrode of electrical double layer capacitor. The AC-2200 electrode presents a low value for Rct and can be used as electrochemical sensors, because a large electroactive area together with the low Rct favors the detection sensitivity.
(Invited) New Advances in Magnetic Properties of Endohedral Metallofullerenes
Authors: Popov Alexey A.
Published: February 2020

An ongoing quest for lanthanide single molecule magnets (SMMs) operating at ever higher temperatures resulted in an impressive progress over the last two decades. On the next step from fundamental research to prospective applications, i.e. as components of spintronic devices, one has to consider stability and processability of SMM materials. Air-stability, thermal stability, ability to form thin molecular layers on different substrates are among the critical issues to be addressed. Encapsulation of magnetic species within robust molecular containers appears to be a natural route towards SMMs fulfilling required stability criteria. Chemical and thermal stability of carbon cages, fullerenes, makes them perfectly suitable for this goal. Fullerenes can encapsulate up to four metal atoms within their inner space, and a number of lanthanide EMFs was found to show SMM behavior. Besides, EMF-SMMs can form monolayers by sublimation or by self-assembly from solution, and such monolayers retain their SMM properties on metallic substrates. In this contribution we will highlight recent developments in the field of lanthanide-EMFs with peculiar magnetic properties.