bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of Pressure-Stress Coupling in Hydrated Palladium
Authors: Madi Reddy Shiv Krishna Reddy , Weidner John W.
Published: February 2020

Hydrogen is considered to be a promising element which has specific energy over 120 MJ/kg highest energy per mass of any fuel. However, its low ambient temperature density leads to low volumetric density, therefore requiring the development of energy storage systems that have potential for higher volumetric density. In this context, we are storing hydrogen within metals by absorption. Here, we report on the stress evolution of metal during hydrogen absorption which is due to the lattice expansion of the hydrogen absorbing phase during hydrogen uptake. The stress induced by material based hydrogen absorption and desorption in very thin palladium layers was recorded in situ using a specially designed cell. Influences of gas pressure, temperature and metal geometry on the stress evolution were considered. In this regard, so called pressure-stress isotherms are proposed in thermomechanical analogy to pressure composition isotherms. The importance of the coupling is discussed in interpreting the hysteresis observed in the pressure versus hydrogen content plots and the role of stress in modifying the maximum hydrogen capacity of a metal hydride under stress.
Exchange-Coupled Sm2Co17/FeCo Core-Shell Nanomagnets Via the Combination of Electrospinning and Electroless Deposition
Authors: Lee Jimin , Yoo Bongyoung , Kim Hee Taik , Kim Jongryoul , Choa Yong-Ho
Published: February 2020

In this study, we performed a novel synthesis of one-dimensional (1-D) SmCo/FeCo core-shell nanomagnets with noticeably enhanced exchange-coupling interactions via electrospinning and a subsequent heat treatment process coupled with an electroless plating process. We discuss the influence of the 1-D shape in enhancing the magnetic properties, particularly exchange-coupling interactions of the rare-earth magnet, compared to the zero-dimensional (0-D) core-shell magnet.

With the advent of high-efficiency miniaturized devices in modern industry, there is high demand for enhanced permanent magnets. Their applications are wide-ranging and include motors in automobiles, data storage devices, electromechanical devices, and electronics. Theoretically, one way to improve the inherent magnetic properties of rare-earth nanomagnets (i.e., SmCo) is to fabricate a soft magnet (i.e., FeCo)-coated core-shell nanomagnet that participates in exchange-coupling interaction with the interphase. However, many previous reports showed only marginal enhancement in magnetic properties, ascribed to the inevitable tendency of 0-D nanoparticles to agglomerate, resulting in non-ideal magnetic coupling. Moreover, there have been no reports on SmCo-based core-shell nanoscale magnets with a 1-D structure, and the effect of magnet shape on the magnetic properties (particularly on exchange-coupling effect) is not well understood. In this regard, such a comparison is a meaningful approach in the design of permanent magnets for achieving effective magnetic coupling.

We clarified the distinct effect of magnet shape based on the analytical results. Interestingly, despite the tailored thickness of the FeCo layer on the Sm2Co17, there was no increase in magnetization or (BH)max enhancement in 0-D magnets, resulting from agglomeration, while 1-D magnets showed an all-time high effective exchange-coupling interaction. Substantial enhancement in magnetization and a (BH)max value of about 10.14 MG·Oe were obtained in the 1-D nanostructure, representing straightforward enhancement of greater than 145% compared to 0-D magnetic nanostructures.

Our work also elucidates the magnetic behavior within the hard-soft magnetic phases of the 1-D SmCo/FeCo nanocomposite, including a comparison with the 0-D bi-magnet. We expect that this understanding can be extended to synthesis of a super-strong exchange-coupled magnet, overcoming the limitations of traditional magnetic materials. Moreover, the present work would be of particular interest to researchers working on a broad range of syntheses and advanced magnetic devices.

Figure 1
Evaluating Li/CFx Cell Components for Deep Space Space Exploration
Authors: Brandon Erik J. , Billings Keith J. , Ratnakumar Bugga V. , Chin Keith B. , Jones John-Paul , Jones Simon C. , Pasalic Jasmina , Ruiz John Paul , Seong Jessica , Stariha Sarah A.
Published: February 2020

To meet the future demands of space exploration will require primary batteries offering higher specific energy, relative to heritage space rated cells based on Li/SO2, Li/SOCl2 and Li/MnO2 chemistries. Cells based on the Li/CFx chemistry are currently under development to support operations in challenging extreme environments. One such proposed application of advanced primary cells is for a proposed Europa Lander, which would analyze the icy surface of this Jovian moon, evaluate its potential for habitability, and investigate for signs of bio-signatures. To address this unique mission requires a detailed understanding of the effects of wide temperatures and radiation on cell electrical and thermal performance, self-discharge characteristics and reliability. In particular, results from screening of cell components will be reviewed, including electrodes and electrolytes experiencing high doses of ionizing radiation.

The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by the Europa Lander Pre-Project.
Advanced Li Metal Batteries: Thermal Safety Evaluation, Analysis and Mechanistic Elucidation
Authors: Puthusseri Dhanya , Pol Vilas G.
Published: February 2020

High theoretical capacity coupled with low operating potential makes Lithium the most promising choice for next-generation batteries. Replacing graphite by Li metal can enhance the energy density three times as compared to conventional Li-ion battery. Lithium is also an essential part of the next generation high energy batteries such as Lithium-Sulphur and Lithium-air batteries. However, the high reactivity of Li metal with electrolyte leads to dendritic growth, poor cycle life and safety hazards in Li metal batteries. Till date, there has been no study on the thermal characteristics of Li metal batteries.

The thermal characteristics of Li metal batteries using advanced multiple-mode calorimetry (MMC) for the coin cell format under fully charged and discharged conditions is studied. In the conventional differential scanning calorimetry (DSC) ex-situ studies of a component or two from the battery, possibly could lead to some artifacts. Therefore, MMC is utilized to directly study the thermal behavior of whole coin cell comprising anode, cathode, electrolyte, and separator with thermally stable leak proof gasket till 300 oC. Thermal runaway of two types of Li metal batteries with different chemistries namely Li-Sulfur and Li-NMC are measured and compared. The MMC of Li-S battery coin cell in fully charged conditions showed a sharp exothermic peak positioned at 180 °C originating from the reaction between the Li metal and sulfur in presence of the electrolyte. Though Li-S batteries are assumed to be safer, an exothermic reaction between Li and S cathode leads to thermal runaway once the Li metal melts. The MMC of Li-NMC cell in the coin cell format also exhibits endothermic and exothermic peaks arising from the melting of Li and reaction of Li with electrolyte/cathode. This exothermic reaction leads to thermal runaway in Li-NMC around 180°C. The detailed endothermic and exothermic heat generation values in J/g, peak temperature, its source based on interfacial reactions and mechanistic elucidation will be discussed.
Investigation of Manipulated Interface in Conventional Electrolytes for Rechargeable Magnesium Battery Application
Authors: Wang Hui , Feng Xuefei , Liu Yi-Sheng , Murugesan Vijayakumar , Zhang Ji-guang , Guo Jinghua , Mueller Karl T , Shao Yuyan
Published: February 2020

Conventional electrolytes made by mixing simple Mg2+ salts and aprotic solvents, analogous to those in Li-ion batteries, are incompatible with Mg anodes because Mg metal readily reacts with such electrolytes, producing a passivation layer which blocks Mg2+ cation transport. Here, we report that, through tuning a conventional electrolyte—Mg(TFSI)2 (TFSI- is N(SO2CF3)2
-) with an Mg(BH4)2 additive—highly reversible Mg plating/stripping with high coulombic efficiency close to 100% is achievable, by decoupling the interaction between Mg2+ and TFSI- and enhanced reductive stability of free TFSI-. A critical adsorption step between the Mg0 atoms and active Mg cation clusters involving BH4
- anions is demonstrated on evolving electrified interface based upon analysis of distribution of relaxation times (DRT) from operando electrochemical impedance spectroscopy (EIS), operando electrochemical X-ray absorption spectroscopy (XAS), nuclear magnetic resonance (NMR), and density functional theory (DFT) calculations. This study suggests a new approach for developing advanced electrolytes and provides an in-operando analysis kit of probing electrified interfaces with adsorption of active Mg cation clusters for rechargeable Mg batteries.
(Invited) An Evaluation of Electrochemical Properties for a Series of Sodium-Ion Battery Anodes
Authors: Johnson Christopher S.
Published: February 2020

It is now established from battery pack engineering modeling calculations, that a Na-ion battery operating at 3.3 V, employing an anode (negative electrode) with a capacity of 500 mAhg-1, and a 200 mAhg-1 cathode (positive electrode) will provide upwards of 15-20% higher energy density (gravimetric basis) over current Li-ion batteries (i.e. 200-225 Whkg-1).1 Of course, reaching such capacity goals of the anodes and cathodes for Na-ion batteries remains very challenging. In this presentation, a number of anode materials’ chemistry and electrochemistry will be evaluated and discussed. These systems include sodium alloys with Sn, Sb, Bi, Ge in carbon-composite particles or in elemental thin-film form, SnSb intermetallics, nano-tube TiO2 and Na2-xHxTi2O4(OH)2, conversion anodes like Sb2O4, Co3O4, Fe2O3, Fe3O4, PbO, Pb3O4, Sn-Na2O conversion-alloying composite, and lastly, spherically-shaped hard carbons. Notably, the Sn-Na2O conversion-alloying composite yields promising target 500 mAhg-1 capacity at C/10 rate for 500 cycles. An interesting mechanism is at work here, whereby the Na-Sn forms an amorphous Zintl phase such that the negative charge at deep sodiation collects on the Sn atom in the compound. This process is believed to minimize overall volume changes in the (de)sodiation process which aids in the good reversibility of the material.

[1] http://www.cse.anl.gov/batpac/index.html
Synergistic Effect of 3D Current Collectors and ALD Surface Modification for High Coulombic Efficiency Lithium Metal Anodes
Authors: Chen Kuan-Hung , Sanchez Adrian J. , Kazyak Eric , Davis Andrew L. , Dasgupta Neil P.
Published: February 2020

Improving the performance of Li metal anodes is a critical bottleneck to enable next‐generation battery systems beyond Li‐ion. However, stability issues originating from undesirable electrode/electrolyte interactions and Li dendrite formation have impaired long‐term cycling of Li metal anodes. In this work, we have developed a bottom‐up fabrication process of vertically aligned and highly uniform Cu pillar arrays on a Cu foil via templated electrodeposition for use as a 3D current collector.[1] By rationally controlling geometric parameters of the 3D current collector architecture, including pillar diameter, spacing, and length, we have demonstrated the morphology of Li plating/stripping upon cycling can be controlled and optimal cycling performance can be achieved.

In addition, we showed that deposition of an ultrathin layer of ZnO by atomic layer deposition on the current collector surface can facilitate the initial Li nucleation, which dictates the morphology and reversibility of subsequent cycling. This core–shell pillar architecture allows for the effects of geometry and surface chemistry to be decoupled and individually controlled to optimize the electrode performance in a synergistic manner. Using this model platform, we have demonstrated Li metal anodes with Coulombic efficiency up to 99.5% at 0.5 mA/cm2 and 99.4% at 1 mA/cm2, which are among the highest reported values to date. The results gained from this work can thus provide a pathway toward high‐efficiency and long‐cycle life Li metal batteries with reduced excess Li loading.

[1] K.-H. Chen, A.J. Sanchez, E. Kazyak, A.L. Davis, N.P. Dasgupta, Adv. Energy Mater.
9, 1802534 (2019).
Effect of the Particle-Size Distribution on the Electrochemical Performance of a Red Phosphorus-Carbon Composite Anode for Sodium-Ion Batteries
Authors: Capone Isaac , Pasta Mauro
Published: February 2020

Sodium-ion batteries will have an important role as a complement to lithium-ion in a future where lithium or cobalt, two critical elements for lithium-ion batteries, become scarce or prohibitively expensive. Red phosphorus (RP) is a promising candidate as an anode for sodium-ion batteries because of its low potential and high specific capacity. Its main disadvantage is its 490% volumetric expansion during sodiation. This leads to particle pulverization and substantial reduction of the cycle life. Furthermore, RP has an extremely low electronic conductivity of 10-14 S cm-1. Both issues have been previously addressed by ball milling RP with a carbon matrix. This decreases the RP particle size and also forms a more electronically conductive composite. However, it is challenging to determine the RP particle size independent of the size of the composite particles. Consequently, little is known about how much the RP particle size must be reduced to improve anode performance. We quantified the relationship between the RP particle-size distribution and its cycle life for the first time by separating the ball milling process into two steps. An initial wet ball milling is used to control the RP particle-size distribution, which is measured via dynamic light scattering. This is followed by a dry milling step to produce RP-graphite composites. We found that wet milling breaks apart the largest RP particles in the range of 2 to 10 µm decreases the Dv90 from 1.85 to 1.26 µm and significantly increases the cycle life of the RP. The RP with a Dv90 of 0.79 µm mixed with graphite for 48h delivered 1,354 mA h g-1 with high coulombic efficiency (>99%) and cyclability (88% capacity retention after 100 cycles). Furthermore, we determined that the length of time of the second milling step affects the uniformity of the carbon distribution in the composite. Photoelectron spectroscopy and transmission electron microscopy confirms the successful formation of a carbon coating, thus improving the performance of the resulting material. These results are an important step in the development of cyclable, high-capacity anodes for sodium-ion batteries.

Figure 1
Advances in Lithium Air Batteries
Authors: Campbell Tedric , Johnson Lonnie
Published: February 2020

Venus is a planet of great scientific interest. It is our closest neighbor and the most similar to Earth in size and location in the solar system. However, at around 500oC, Venus also has one of the most hostile surfaces in the solar system. Venus’ high temperature environment in combination with its CO2 rich atmosphere presents an attractive opportunity for using Lithium-CO2 reactions as a power source having exceptionally high specific energy. In this study we analyze an approach for achieving an electrical energy capacity of 7.6kWh/kg using a high temperature, Lithium/CO2 primary electrochemical cell with a solid state ceramic electrolyte.
Development of Cathode and Electrolyte Materials for Lithium-Oxygen Batteries for Electric Aviation
Authors: Dornbusch Donald A. , Radhakrishnan Balachandran , Viggiano Rocco , Dynys Frederick W. , Lawson John W
Published: February 2020

Lithium-Oxygen and Lithium-Air batteries promise high theoretical energy densities that are significantly greater than current lithium-ion technology and available from an abundant ambient resource. The advantage of such a high-energy active material that could be extracted from ambient air could help achieve the strict requirements for electric and hybrid aviation. However, the major limiting factor for adopting these systems is the high rate of degradation and side-product formation in non-aqueous electrolytes utilizing carbon cathode supports.The decomposition of organic electrolyte and carbon cathode result in poor cycling performance due to build up of intermediates, such as lithium-carbonate (Li2CO3), at the cathode surface, and resulting in poor cycle efficiency. In this study, a combined approach utilizing both computational modeling and experimental screening was used to investigate novel electrolytes and carbon-free cathode materials to reduce or avoid the generation of carbonates during cell operation.
Development of Silicon Anode for All-Solid-State Thin-Film Secondary Battery
Authors: Suzuki Akiyoshi , Sasaki Shunsuke , Jimbo Takehito
Published: February 2020

Thin-film batteries (TFBs) are produced by thin-film deposition technology which has special advantages that are not only intrinsically safe as their being all-solid-state but also thin, small, lightweight, and flexible [1], and also have the features such as low self-discharge and long cycle-life. As MEMS and high-density packaging technology grows, the device size becomes smaller and there is a growing demand for miniaturized devices with stand-alone power supply supported by TFBs and energy harvesting devices [2, 3]. However, Li metal that is commonly used as anode in TFBs, has low melting point as around 180 deg.C and cannot be employed for packaging process that include solder reflow, epoxy molding, and even through-silicon via (TSV). Si is promising anode material due to high specific capacity and low electrode potential, but there are the issuers such as low resistance and electrode breakage due to drastic volume change during cycles.

In our previous work, TFBs with high-temperature tolerance was fabricated by all sputtering; Pt/Ti as cathode current collector, 3μm-thick-LiCoO2 with post-annealed at around 600 deg.C as cathode, 2 μm-thick-LiPON as solid electrolyte, 600 nm-thick-Si1-xTix (x=0, 0.03, and 0.12) as anode, and Ni as anode current collector [4], and finally completed by encapsulation with UV curable resin and inorganic lid. The active area of fabricated TFBs was 1.4 mm2. Ti which is inactive material against Li, was used as dopant for not only mitigating mechanical stress but also decreasing resistivity. Cycling was performed between 2.5 and 4.1 V with standard current rate condition, and cycle performance resulted well during 100 cycles. In this work, microstructure of Si-Ti alloy film was adjusted by changing sputtering condition such as process pressure and gas species. Figure 1 shows cross-sectional SEM image of each Si1-xTix films. The effect of Si1-xTix anode microstructure on electrochemical and cycle performance of full cell will be discussed.

References

[1] T. Jimbo, P. Kim, and K. Suu, Production technology for thin-film lithium secondary battery, Energy Procedia, 14, 1574-1579 (2012).

[2] M. Fojtik, D. Kim, G. Chen, Y. S. Lin, D. Fick, J. Park, M. Seok, M. T. Chen, Z. Foo, D. Blaauw, and D. Sylverster, A millimeter-scale energy-autonomous sensor system with stacked battery and solor cells, IEEE Journal of Solid-State Circuits, 48 (no. 3), 801-813 (2013).

[3] T. Kuriyama, A. Suzuki, Y. Okamoto, I. Kimura, Y. Morikawa, and Y. Mita, A micromachined all-solid on-chip thin-film battery towards uninterruptible photovoltaic cells, 2018 Symposium on Design, Test, Integration and Packaging of MEMS and MOEMS (DTIP), 153-156 (2018).

[4] A. Suzuki, S. Sasaki, and T. Jimbo, Development of All-solid-state Thin-film Secondary Battery for MEMS and IoT Device, The 18th International Conference on PowerMEMS 2018, Proceedings, T5A-03 (2018).

Figure 1
Electrochemical Kinetics in Solid Battery Electrolytes
Authors: Hallinan Daniel T. , Majeed Muneeb , Kim Kyoungmin , Berliner Marc
Published: February 2020

Solid electrolytes are of interest for improved battery safety and compatibility with advanced electrodes (such as lithium metal). They could potentially enable flexible, efficient batteries with the use of single-ion conducting polymer or composite electrolytes. However, the rate capability of solid-state batteries is problematic, as is long-term stability with certain electrode chemistries. In order to better understand these limitations, we have developed a pulsed voltammetry method to study electrode reaction kinetics in cells with solid polymer electrolytes. Traditionally, a rotating disk electrode has been used to study reaction kinetics in liquid electrolytes. This method minimizes mass transfer limitations by rotating the working electrode so that reaction kinetics can be accurately measured. Since electrode rotation is not possible in solid electrolytes, we use short, constant-voltage pulses and collect a current measurement. Then the cell is left at open circuit for an extended period of time to dissipate any concentration gradients that developed during the measurement. After sufficient relaxation, another pulse to a different voltage is made. Measurement at early time minimizes mass-transfer contribution to the measurement. We have validated this technique against rotating disk electrode measurements in a liquid electrolyte. It has also been applied to study oxidative degradation of polymer electrolyte and lithium and plating kinetics. The latter study is of particular interest due to the fact that a connection between reaction kinetics and lithium dendrite morphology has been observed in some systems. The solid polymer electrolyte used in this work consists of lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI) dissolved in polystyrene-b-poly(ethylene oxide) block copolymers. The kinetic measurements from pulsed voltammetry will be compared to electrochemical impedance spectroscopy measurements and lithium surface morphology analysis. Interesting effect of salt concentration will also be presented.
(Invited) Understanding of the Electrochemical Performance of Lithium-Sulfur Batteries with Different Sulfur Electrode Porosities
Authors: Kang Ning , Lin Yuxiao , Yang Li , Cai Mei
Published: February 2020

Li-S battery is widely considered as one of the most promising candidates for the next generation energy storage devices due to its high theoretical capacity and energy density. However, the actual performance of the whole Li-S battery is highly impacted by the structure of cathode materials and the amount of electrolyte.

In this talk, the performance of Li-S battery was studied based on different cathode porosities (40% ~ 70 %). It was shown that the two discharging plateaus were both affected as the porosity is lower than 50%. The capacity of the first plateau around 2.4 V was shortened while the voltage in the second plateau around 2.1 V was highly depressed, leading to a lower energy density.

To further understand the design limitations, a combined experimental and modeling approach was utilized to determine the limiting factor in each plateau and predict the relationship between energy density and porosity. It was revealed that the first plateau was mainly limited by the amount of soluble polysulfide while the second plateau was limited by the surface area of the carbon matrix. Since a decreased porosity would have a negative influence on both limiting factors, an optimal porosity is predicted for maximum energy density. A consistency between modeling prediction and experimental observation was obtained, suggesting the validation of this model.
(Invited) Li-ion safety of consumer cells and EDV cell (What, How, Why)
Authors: Zhang Zhengming John
Published: February 2020

Constant safety problem of Li-ion batteries, either in EDV or consumer applications create concerns. We have been actively discussing the understanding, the reduction, the prevention and/or the eliminations of Li-ion safety at various applications in IEEE and SAE with hundreds industrial leaders from various organizations. Some of the results of our discussion on the “understanding” will be shared in this presentation.
(Invited) Electrochemical and Chemical Stability of Solid State Electrolytes and Coating Materials for Solid-State Batteries
Authors: Ceder Gerbrand , Miara Lincoln J. , Wang Yan Eric , Xiao Yihan
Published: February 2020

Solid-state batteries represent an exciting future direction for energy storage. While tremendous progress has been made in developing novel solids with very high Li-ion conductivity, electrochemical decomposition and reactivity of conductors with the anode or cathode material remains a major concern for the long-term stability of solid-state batteries. Using ab-initio computations we have evaluated the chemical and electrochemical stability of a large number of coating materials and conductors. I will discuss the clear set of chemical rules that appears from these results. Interestingly, the optimal coating materials depend very much on the specific electrode/conductor interface that needs to be protected.
Quenching Cathode Electrolyte Interphase on Ni-Rich Cathode Materials for Preventing Short Circuit Problem in Lithium Ion Battery
Authors: Wang Fu-Ming
Published: February 2020

In January 2017, Samsung announced the reason why the Note 7 explodes and losses of more than 5 billion US dollar. According to their explanations, it was caused by the internal short circuit problem in the lithium ion battery. Currently, there is no effectively solution for eliminating the internal short circuit problem owing to the sudden accident.

In this research, a new technology has been developed, which can be used to terminate the thermal runaway and promise the safety performance of lithium ion battery. High voltage Li-excess and Ni-rich layer-type cathode material is employed and combined with this safety electrode additive for investigation. In terms of the results, the new technology LIVING@additive significantly enhances the cycle performance at 60oC and high voltage. In addition, the following figures illustrated that the battery containing LIVING@technology is stable and passed the nail penetration test. On the other hand, the battery without LIVING@ cannot be used when the short problem is taking place. The LIVING@contains self-polymerized hyper branch structure in order to insulate the directly contact between anode and cathode. This electrode additive not only provides high thermal stability on electrochemical reaction, but the columbic efficiency of charge-discharge is also enhanced.

Keywords: Lithium ion battery, safety, cathode electrolyte interphase, Ni-rich
Co-Free Cathode Material with Simultaneous MgO Coating and Mg Doping for High-Voltage Sodium-Ion Batteries
Authors: Yu Tae Yeon , Sun Yang-Kook
Published: February 2020

To simultaneously address the inherent limitations of the capacity and cycling instability of Na[Ni0.5Mn0.5]O2 cathodes, it is necessary to concurrently stabilize particle surfaces and crystal structure. Encouraged by previously conducted research activities in this field, we have adopted an effective strategy for simultaneous MgO coating and Mg doping to produce substantially improved high voltage stability compared to the previously reported results in the literature on Na[Ni0.5Mn0.5]O2 cathodes. The MgO coating layer effectively suppressed the unfavorable side reactions during cycling while the partial Mg doping into the bulk Ni sites improved the structural stability by moderating the extent of the irreversible multiphase transformation. As a result, the combination of a MgO coating with Mg doping provides enhanced electrochemical performance and structural stability of Na[Ni0.5Mn0.5]O2 within the voltage range of 2.0–4.2 V. The practical acceptability of the simultaneous MgO coating and Mg doping of the Na[Ni0.5Mn0.5]O2 cathode was obviously verified using scaled-up pouch-type full cells with hard carbon anodes. Compared with previously reported similar cathode materials, the proposed MgO-NM55 cathode showed great competitiveness for high-voltage stability in SIBs. Moreover, the use of earth's abundant and inexpensive Mg and Na elements, and a simple practical strategy are highly desirable for developing high-energy and low-cost SIBs. Although the practical use of the MgO-NM55 cathode in SIBs will require further work, the methodology used in this study will be helpful in developing an efficient design of high performance cathode materials for SIBs.

References

J.-Y. Hwang, S.-T. Myung and Y.-K. Sun, Soc. Rev., 2017, 46, 3529–3614.

J.-Y. Hwang, C. S. Yoon, I. Belharouak and Y.-K. Sun, J. Mater. Chem. A, 2016, 4, 17952.

P.-F. Wang, H.-R. Yao, X.-Y. Liu, J.-N. Zhang, L. Gu, X.-Q. Yu, Y.-X. Yin and Y.-G. Guo, Adv. Mater., 2017, 29, 1700210.

S. Komaba, N. Yabuuchi, T. Nakayama, A. Ogata, T. Ishikawa and I. Nakai, Inorg. Chem., 2012, 51, 6211.
The Effect of Polymeric Binders in the Sulfur Cathode on the Cycling Performance for Lithium-Sulfur Batteries
Authors: Eom Ji-Yong
Published: February 2020

Recently, great advance of the Li-S battery technology enables its penetration to the power source of the mid- and large-sized devices, which require high energy and power density that cannot be achieved in the Li-ion battery. While the most successful sulfur cathode could be designed by the optimization of the composite structure with carbonaceous materials, the binder system has been recently considered another important factor because the electrode structure of the sulfur cathode suffers huge structural change during the repeated electrochemical cycles. We studied the structural and electrochemical performance of the sulfur cathodes prepared by two different binders, the water-soluble SBR/CMC mixture binder and the traditional PVdF binder. The enhanced battery performance was observed in the SBR/CMC-based electrode and its origin was investigated by post mortem analysis about the electrodes, which confirmed the better mechanical integrity in the electrode compared with the PVdF-based electrode.
Graphene Based Composite Fiber for Wearable Supercapacitor and Li Ion Battery
Authors: Yu Aiping
Published: February 2020

Graphene fibers (GF) have received great interest in wearable electronics applications because of their excellent mechanical flexibility and superior electrical conductivity. Herein, an all-in-one graphene and MnO2 composite hybrid supercapacitor fiber device has been developed. The unique coaxial design of this device facilitates large-scale production while avoiding the risk of short circuiting. The core backbone of the device consists of GF that not only provides mechanical stability but also ensures fast electron transfer during charge−discharge. The introduction of a MnO2 (200 nm in length) hierarchical nanostructured film enhanced the pseudocapacitance dramatically compared to the graphene-only device in part because of the abundant number of active sites in contact with the poly(vinyl alcohol) (PVA)/H3PO4 electrolyte.

The entire device exhibits outstanding mechanical strength as well as good electrocapacitive performance with a volumetric capacitance of 29.6 F cm−3 at 2 mv s−1. The capacitance of the device did not fade under bending from 0° to 150°, while the capacitance retention of 93% was observed after 1000 cycles. These unique features make this device a promising candidate for applications in wearable fabric supercapacitors. Furthermore, the materials were applied to fabricate Li ion battery and the initial data is promising and more analysis is underway.
How Do Li-S Electrolytes with Reduced Polysulfide Solubility Work – an Impedance Spectroscopy Investigation
Authors: Drvarič Talian Sara , Johansson Patrik , Gaberscek Miran , Dominko Robert
Published: February 2020

Use of fluorinated ether (TFEE) based electrolyte in lithium-sulfur (Li-S) batteries enables high-energy Li–S cells at low electrolyte loading by significantly reducing the polysulfide shuttle phenomenon. The molecular level origin for the change in polysulfide solubility was found to be poor Li+ ion solvation ability of the fluorinated ethers as analyzed by COSMO-RS computations for several electrolytes.1

There are still several questions open about the mechanism of operation of such cells. How is impedance and its limitations different from the conventional polysulfide solvating electrolytes? Which process during the operation of such cells is the bottle-neck for cell performance? What is the mechanism of Li2S deposition? Is lithium stripping and deposition limited by the poor Li+ ion solvation ability?

In order to understand the cell performance with TFEE electrolyte, an impedance spectroscopy study was conducted on simplified cell geometry model systems. The basic principles elucidated through that approach were then used to understand the workings of the conventional mesoporous carbon cathode cell setup. Charge transfer reaction and diffusion contributions were evaluated and the change due to Li2S deposition analyzed. Finally, Li metal stripping and deposition analysis was performed, which showed beneficial effects of the fluorinated solvent on the SEI.

References:

1 S. Drvarič Talian, S. Jeschke, A. Vizintin, K. Pirnat, I. Arčon, G. Aquilanti, P. Johansson, R. Dominko, Chem. Mater. 29 (2017) 10037–10044.

Figure 1
Unraveling the SEI Mystery of Cis/Trans-Butylene Carbonate
Authors: Miyazaki Kasumi , Takenaka Norio , Fujie Takuya , Watanabe Eriko , Yamada Yuki , Yamada Atsuo , Nagaoka Masataka
Published: February 2020

A solid electrolyte interphase (SEI) film is a key to stable battery performance. Of particular importance in designing SEI is in its strong dependence on electrolyte solvent. The most representative example is the distinct difference between ethylene carbonate (EC) and propylene carbonate (PC); EC-based electrolytes have ability to form good SEI film on graphite anode surface, while PC-based electrolytes do not, in spite of their slight difference (only one additional methyl group) in a molecular level. A similar relationship to the phenomena called “EC-PC mystery” was found in other cyclic carbonates: trans-butylene carbonate (t-BC, reversible with SEI) and cis-butylene carbonate (c-BC, irreversible without SEI),1,2 where the difference in single molecule is even smaller found just in cis-trans geometries.

To unveil the mystery, details of SEI film formation processes on the graphite anode were simulated by Red Moon (RM) method,3–5 with interface models and hypothetical essential elementary chemical reactions as shown in the figure. We found that the SEI film formed in c-BC-based electrolyte contains less number of dimerized products Li2(BC)2, a primary component of good SEI film, and can cause lower stability of the film. As an origin of the reduced dimerization in c-BC, we identified larger solvation energy of c-BC to the intermediate LiBC and its smaller diffusion constant, which largely diminishes the LiBC-LiBC collision frequency. More details on contribution of each elementary steps will be discussed in the poster.

References

[1] Chung, G.-C. et al., J. Electrochem. Soc. 2000, 147 (12), 4391–4398, [2] Chung, G.-C., J. Power Sources 2002, 104, 7–12, [3] Fujie, T. et al., J. Chem. Phys. 2018, 149 (4), 44113, [4] Takenaka, N. et al., J. Phys. Chem. C 2014, 118 (20), 10874–10882, [5] Nagaoka, M. et al., Chem. Phys. Lett. 2013, 583, 80–86.

Figure 1
The Effect of Electrolyte Additives on High Cut-Off Voltage Electrochemical Performances of LiNi0.5Mn0.3Co0.2O2/Graphite Full
Authors: Im Jinsol , Park Eun Ji , Lee Sang Hyun , Cho Kuk Young
Published: February 2020

As the demand for electric vehicles and energy storage systems expands, it is essential to increase the capacity of Li-ion batteries (LIBs) applied to mid- and large-sized devices. High voltage operation of LIB and the use of high capacity electrode materials are common ways to increase the battery capacity. However, there are several problems caused by structural instability, when these electrodes are operated at high voltage. The approach of using functional additives in electrolyte is one of the effective way to improving performances. In this study, the effect of adding the functional additives in electrolyte on full cell performance at high voltage was investigated. The cycle performance of the cell operated at cut-off voltage of 4.5 V with the additives showed improvement than that of coin cell without additives. SEM image of the cycled electrodes surface with additives showed more clear morphology. It can be observed that the introduction of new functional additives effectively reduces the cell resistance by inhibiting formation of by-products during the cycling which was confirmed from the result of AC impedance and SEM images. Furthermore, the XRD patterns of the electrodes after cycling exhibited improved stability with the addition of functional additive used in this work. Our results clearly indicate the significance of additive selection for promising high voltage operation of lithium-ion batteries.
Crystal Engineering Coupled with Theoretical Approach Toward Facet, Interface-Controlled All Solid-State Electrode
Authors: Teshima Katsuya , Yamada Tetsuya , Zettsu Nobuyuki
Published: February 2020

Lithium ion secondary batteries (LIBs) have been widely used as energy-storage system for variety of power devices. It is necessary to further develop LIBs toward high-functional devices, such as electric vehicles and mobile electronics. Nowadays, all solid-state LIBs have been much interested because of a variety of potential advantage, including energy densities, cost, size, safety, and operating temperature. However, there are serious problems to be solved toward practical uses. For example, diffusion of lithium ions at interface between different solid materials, including active materials and electrolytes, is still poor to operate charge/discharge in batteries. Our group has studied high-quality crystals for applications as energy and environmental materials by using a flux method. Flux method is a nature-mimetic liquid-phase crystal growth technique. Fluxes accord to salts, which work as solvent at temperature over their melting and / or eutectic points. By using fluxes, it is possible to construct specific crystal-growth field at any temperature with facile setup, and give designed crystals regarding to shape, including crystal faces, which has never achieved using other methods like solid state reaction.

Recently, we have applied the flux method to battery materials to create “all-crystal (solid)-state LIBs”. We have expected that flux crystal growth gave (I) crystal-shape control of active materials, (II) construction of good interfaces in electrodes among cathodes, solid electrolytes, and anodes. The second topics would be possible if electrode materials can be dissolved and densely recrystallized on their surfaces. As a result, smooth ionic transportation through bulks and their interfaces would be realized in all-crystal (solid)-state LIBs. Our concept using flux method would provide new aspect to lead an innovation in all solid state LIBs as next-generation energy storage. In the presentation, the details of interfacial and crystal designs of a variety of battery materials will be introduced, coupled with their crystallographic, ionic, and battery properties.

Acknowledgement

This work was supported by JST CREST Grant Number JPMJCR1322 in Japan and Program for Building Regional Innovation Ecosystems of MEXT.
In Situ Characterization of Si-Based Anodes By Coupling Synchrotron X-Ray Tomography and Diffraction
Authors: Vanpeene Victor , King Andrew , Maire Eric , Roué Lionel
Published: February 2020

In the present work, combined synchrotron X-ray tomography/diffraction analyses are performed along the 1st and 10th cycles of a Si-based anode [1]. An electrode volume of 943 × 943 × 208 µm3 is imaged with a voxel size of 0.65 µm. The electrode is made with nanocrystalline/amorphous Si particles synthetized by ball-milling as active material, a porous C paper as a current collector instead of a conventional Cu foil and graphene nanoplatelets as a conductive additive instead of usual carbon black. It is shown that this specific formulation has a major impact on the structural changes of the electrode occurring upon cycling by (i) preventing its macroscopic cracking and related electrical disconnections, (ii) limiting its volume expansion and improving its reversibility, indicative of limited permanent damage in the electrode architecture, (iii) preventing the formation of c-Li15Si4 which is known to be detrimental for the electrode cyclability. However, the capacity fade with cycling remains significant. It can result from the accumulation of SEI products with cycling, progressively obstructing the porous network of the electrode, as supported by a significant decrease of the electrode porosity between the 1st and 10th cycle. The displacement and/or micro-cracking of the Si particles can also induce some electrical disconnections and irreversibility of the lithiation reaction. However, this degradation process occurring at the particle scale cannot be clearly identified from the present in-situ XRCT measurements due to spatial resolution limitation.

[1] V. Vanpeene, A. King, E. Maire, L. Roué. In situ
characterization of Si-based anodes by coupling synchrotron X-ray tomography and diffraction. Nano Energy 56 (2019) 799-812

Figure 1
(Invited) Reaction Mechanism of Lithium Excess Layered Manganese Oxides Studied By Thin-Film Model Electrodes and Operando Measurements
Authors: Kanno Ryoji , Hikima Kazuhiro , Kiuchi Hisao , Suzuki Kota , Hirayama Masaaki , Matsubara Eiichiro
Published: February 2020

The reaction mechanism of lithium excess manganese oxide, Li2MnO3, with layered rock-salt structure was examined using model thin film electrodes with liquid or solid electrolytes. The epitaxial or polycrystalline films with 30 nm-thick with various compositions and morphologies were fabricated using pulsed laser deposition and sputtering methods. These electrodes showed charge-discharge capacity ranging from 150 to 300 mAh g-1with different degradation characteristics depending on the compositions and morphologies. The reaction mechanisms were studied by in-situ and operando methods using surface X-ray diffraction and HAXPES analyses. The Li2MnO3shows a transformation to a high-capacity phase after the activation process by the first charge and the degradation during the subsequent cycling depends on the sample stoichiometry and morphology. The transition to the high capacity phase is related the phase change from the O3 to O2 type, together with the interlayer cation disordering on the Li/Mn layer. The activation process is related to the oxidation of oxygen and a formation new oxygen species together with the reduction of the manganese from tetra-valent state. The activation process and the reversible reactions of the lithium-rich layered rock-salt materials are elucidated.
Influence of Modification on the Charge Transfer Process and Strain of LiNi0.6Co0.2Mn0.2O2
Authors: Wang GuiXin , Tang Wenjie , Zhou Shuo , Peng Zhenfeng , Wei Yun , Shuai Hantao
Published: February 2020

Charge transfer process and strain play a significant role in determining the rate performance and safety property of energy materials. As one of highly interesting materials for portal electronics and electric vehicles, LiNi0.6Co0.2Mn0.2O2 is limited by fade and safety. Some materials, including F and AlPO4, have been adopted to modify LiNi0.6Co0.2Mn0.2O2 to improve the performance. Influence of modification on the structure, surface elemental interaction, and electrochemical performance was investigated with various techniques, and the possible mechanisms were discussed. The changes of charge transfer process and strain were investigated using Cyclic Voltammetry, Electrochemical Impedance Spectroscopy and non-destructive strain gauges at different charge states, respectively. Fluorine modified LiNi0.6Co0.2Mn0.2O2 with different fluorine contents has been synthesized successfully at low temperature using PTFE emulsion as the fluorine resource. In comparison with that of the pristine LiNi0.6Co0.2Mn0.2O2, the initial discharge capacities of LiNi0.6Co0.2Mn0.2O2-yFy (y=0.02, 0.05, 0.08) are slightly decreased at 0.1C, but the capacity retention ratios at higher current densities, higher potential and elevated temperatures are improved. Among the samples with different fluorine contents, LiNi0.6Co0.2Mn0.2O1.95F0.05 exhibits the best performance with lowest charge transfer impedance and strain during cycles. After 50 cycles at 1.0 C between 2.8 and 4.7 V, LiNi0.6Co0.2Mn0.2O1.95F0.05 improves the capacity retention ratio and the discharge capacity of the pristine sample from 80.0% to 90.4%, and from 156.7 to 176.3 mAh g-1, respectively. In order to further improve the high-temperature performance of LiNi0.6Co0.2Mn0.2O2, AlPO4 modification has been carried out using a simple route, and the discharge capacity retention ratio after cycles at 1C at 40 °C and 60 °C were respectively 86.20% and 85.44%, much higher than that of the corresponding values of the pristine sample. Fluorine and AlPO4 modification obviously decreases the strain as well as the residual stress of LiNi0.6Co0.2Mn0.2O2 during charge/discharge processes at evaluated temperatures. Cyclic voltammetry and electrochemical impedance spectroscopy results demonstrate that fluorine and AlPO4 modification significantly decreases the electrochemical polarization and charge transfer reaction impedance of LiNi0.6Co0.2Mn0.2O2 after cycles to enhance performance. The difference between F and AlPO4 modification was compared, and the changes of charge transfer process and strain were analyzed. Modification, a facile way to strengthen charge transfer, is a good alternative to improve the electrochemical performance and safety properties of electrode materials for high-performance batteries.
Dynamic Electrochemistry of Polyaniline Nanoparticle Dispersions
Authors: Gramaglia Romina , Miras Maria Cristina , Bruno Mariano M , Barbero Cesar Alfredo
Published: February 2020

Solid electroactive nanoparticles could be electrochemically oxidized/reduced at solid electrodes, transferring large amounts of charge. Therefore, concentrated dispersions of particles could be used in flow batteries. [1] While an extensive experimental and theoretical work has been made on the electrochemistry of single small nanoparticles (nanoimpact regime)[2], the dynamic electrochemical behavior of large ensembles of electroactive nanoparticles has not been studied. In the present work we describe the experimental study of different dispersions of polyaniline nanoparticles. Polyaniline is a well-known material for conventional batteries.[3] It is shown that nanoparticle adsorption occurs in glassy carbon electrodes. Besides, the charging/discharging of the nanoparticle dispersion is controlled by the combined effect of the nanoparticle diffusion in the electrolyte (which controls the residence time in contact with the electrode) and the charge diffusion inside the nanoparticle (which control the single particle charging/discharging). While small nanoparticles can be changed in a short time, the residence time is also limited due to the larger diffusion coefficient. Therefore, a maximum efficiency of conversion is observed. Moreover, the conversion efficiency could be increased by increasing the viscosity of the electrolytes. On the other hand, the efficiency could be largely increased by introducing a redox mediator which shuttle the charge between the dispersed nanoparticles and the solid electrode.

The relevance of the rate of charging/discharging towards the flow battery applications will be discussed.

References

Z. Qi and G.M. Koenig, J. Vac. Sci. Technol. B. 35, 40801:1-27, 2017.

E. Katelhon, et al, J. Phys. Chem. C. 120, 17029-17034, 2016 and refs therein.

C. Barbero, et al, J. Mater. Chem., 4, 1775-1783, 1994.