bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Polysulfide Solubility and Li Ion Transport on Li–S Batteries Using Sparingly Solvating Electrolytes
Authors: Ueno Kazuhide , Dokko Kaoru , Watanabe Masayoshi
Published: December 2020

Sparingly solvating electrolytes are an emerging class of electrolytes used in Li–S batteries. In this type of electrolytes, polysulfide dissolution and shuttling can be suppressed, leading to high Coulombic efficiency and cycle life. To optimize the electrolytes for high energy density Li–S cells, effects of polysulfide solubility and Li ion transport properties on Li–S battery performance were investigated for tetraglyme (G4)- and sulfolane (SL)-based electrolytes diluted with a hydrofluoroether (HFE). The Li2S8 solubility was found to be very low (1 mM in atomic S concentration) in [Li(G4)0.8][TFSA]-4.3HFE and [Li(SL)2][TFSA]-4.0HFE. Cells with [Li(SL)2][TFSA]-4.0HFE exhibited better rate capability compared with cells with [Li(G4)0.8][TFSA]-4.3HFE despite lower ionic conductivity of [Li(SL)2][TFSA]-4.0HFE. With regard to the Li ion coordination structure in [Li(SL)2][TFSA]-4.0HFE, the two oxygen atoms of the SL sulfonyl group coordinates to two different neighboring Li ions and TFSA anions form ionic clusters with Li ions. The unique SL- and anion-bridged, chain-like Li ion coordination structure was considered to be involved in the unusual Li ion self-diffusion behavior and Li ion tranport for [Li(SL)2][TFSA]-4.0HFE. The higher Li ion transference number measured under anion-blocking condition (t
Li
+) of [Li(SL)2][TFSA]-4.0HFE was suggested to contribute to the better rate performance, rather than the polysulfide solubility and ionic conductivity. Furthermore, [Li(SL)2][TFSA]-4.0HFE demonstrated an initial discharge capacity of 1130 mAh g−1 at a low electrolyte volume to sulfur weight ratio of 4, whereas a typical organic electrolyte failed to achieve such a high capacity owing to limitations of the redox mechanism mediated by dissolved polysulfides. In addition to the low solubility of polysulfides, the high t
Li
+ is crucial for achieving high energy density Li–S batteries by reducing the electrolyte amount. The SL-based electrolytes were found to manifest a significant improvement in Li ion mass transfer as a sparingly solvating electrolyte, enabling the solid-state sulfur redox reactions in high-performance Li-S batteries.

Acknowledgement

This study was supported by the Advanced Low Carbon Technology Research and Development Program (ALCA) of the Japan Science and Technology Agency (JST).

References

1) A. Nakanishi. et al, J. Phys. Chem. C,
2019, 123, 14229.

2) M. Yanagi et al, J. Electrochem. Soc., 2020, 167, 070531.

Figure 1
Silicon Monoxide As Anode Material for Lithium Ion Batteries
Authors: Lu Wenquan , Zhang Linghong , Kirner Joel , Yang Zhenzhen , Qin Yan , Liu Yuzi , Ren Yang , Jansen Andrew N.
Published: December 2020

Silicon monoxide (SiO) is a very promising anode material for the next generation high energy lithium ion batteries due to its high theoretical specific capacity of 1710 mAh/g and volumetric capacity of 1547 Ah/L.[1] Compared to commercially used graphite, SiO can offer 18% cell stack level improvement in volumetric energy density and 11% in gravimetric energy density (calculated based on the same cell stack model), enabling utilization of smaller and lighter batteries. It also offers more stable cycle performance compared to Si due to less volume change (134% initial volume expansion and 117% reversible volume expansion), making it a more practical choice for lithium ion batteries in the near future.

SiO is composed of Si nanodomains in a SiO2 matrix. An interphase region of transitional stoichiometry (SiOx, 0 < x < 2) is also present between Si and SiO2 and takes up 20-25 at.% of the entire composition.[2] During the lithiation and delithiation, the Si nanodomains react reversibly with lithium, similar to amorphous silicon, to give the reversible capacity. The SiO2 matrix reacts irreversibly with lithium to form lithium silicates and lithium oxide. Therefore, the Si domain size and interphase suboxide between Si and SiO2 have effect on the electrochemical performance of SiO. In this study, we gradually changed the microstructure of SiO via annealing treatment and thoroughly studied the change of the SiO microstructure and its impact on the electrochemical performance of the SiO. Together with electrode formulation optimization, up to 99% capacity retention during 50 cycles was obtained in full cells when using pure SiO as anode and LiNi0.5Mn0.3Co0.2O2 as cathode.

Acknowledgement

We gratefully acknowledge the support from Peter Faguy at the U.S. Department of Energy’s (DOE) office of Energy Efficiency & Renewable Energy (EERE) - Vehicle Technologies Office. This work is conducted under the Cell Analysis, Modeling, and Prototyping (CAMP) Facility at Argonne National Laboratory. Argonne National Laboratory is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357.

Reference:

Obrovac, M. N.; Chevrier, V. L., Alloy Negative Electrodes for Li-Ion Batteries. Chemical Reviews 2014, 114 (23), 11444-11502.

Hirata, A.; Kohara, S.; Asada, T.; Arao, M.; Yogi, C.; Imai, H.; Tan, Y.; Fujita, T.; Chen, M., Atomic-scale disproportionation in amorphous silicon monoxide. Nature Communications 2016, 7, 11591.
Tunable Syntheses of Advanced Silicon Anodes Using Cyclohexasilane
Authors: Elgammal Ramez Ahmed
Published: December 2020

The ability to develop fast charging lithium-ion batteries with high-energy density is being pursued intensively due to increasing demands of portable electronics and electric vehicles. Replacing the conventional graphite anode with a silicon-based one offers several advantages, namely the roughly 10 times higher gravimetric capacity and the safer lithium alloying potential. However, full scale realization of replacing graphite with silicon has been hampered due to the large volumetric expansion silicon typically suffers which causes mechanical degradation, low electrical conductivity, and multiple-step syntheses from a traditional silicon precursor which leads to higher cost. Here we present a silicon precursor, cyclohexasilane, that can offer solutions to all three of those limitations. Cyclohexasilane (CHS) exists as a liquid at room temperature and is relatively low boiling (~ 200 °C) relatively facile synthesis of nanostructured silicon materials, significantly reducing the volumetric expansion typically observed. Cyclohexasilane can be readily used to manufacture silicon/carbon composite materials and is readily chemically functionalized allowing the development of tailored materials with improved electrical conductivity. CHS may also be tailored to deliver structures with engineered artificial SEIs during the device fabrication step, offering an efficient and direct route to electrode structures. Moreover, cyclohexasilane is relatively inexpensive and its physical properties allow for roll-to-roll manufacturing with significantly reduced capital costs. Relevant comparisons of this technology compared to incumbent technologies will be given.
Mechanistic Understanding and Rapid Electrochemical Reduction of Silica for Lithium-Ion Battery Anodes
Authors: Entwistle Jake , Patwardhan Siddarthh , Cumming Denis J
Published: December 2020

The use of silica as an active material within a lithium-ion battery requires a pre-treatment. The electrochemical reduction between silica and lithium is partially irreversible and is postulated to produce silicon as a reaction product. The silicon formed can reversibly react with lithium to produce stable capacities, higher than current graphite materials. However, both the electrochemical reduction pathway and the electrochemical reduction products are unknown, thereby hampering the design, optimisation and use of such systems. Here we uncover the pathway for the electrochemical reduction and, for the first time, identify elemental silicon as a product of the reduction. We discovered new methods for studying the electrochemical reduction reaction – they are based on monitoring and analysing the capacity increase and the current flow as the material is reduced. Our results conclusively show that silica must be reduced to introduce reversible capacity and that this reduction reaction time can be greatly reduced using a constant load discharge at elevated temperature. Characterisation with total scattering X-ray pair distribution function shows the reduction products are amorphous in nature and confirmed why previous diffraction characterisation attempts were unsuccessful. Our results can help better understand the electrochemical reduction of any silica material. We anticipate these results can be used as a starting point for the development of a scaled-up synthesis route for in-situ reduced silica anodes and their incorporation into lithium-ion full cells.
Sagoe Starch Derived Hard Carbons As Anodes for Sodium Ion Battery
Authors: Arie Arenst Andreas , Kristianto Hans , Kumalaputri Angela Justina
Published: December 2020

Based on the chemical similarity, large abundance and cheap price, sodium ion battery (SIB) can become a promising alternative to subsitute lithium ion battery (LIB). The main issue of the development of SIB is to look for a suitable anode material since graphite, the anodes in LIB, can not be used in SIB because of the unstable thermodynamic properties . In this work, we report the synthesis of hard carbon anodes for SIB from sagoe starch that are prepared by hydrothermal carbonization followed by the pyrolysis process at moderate temperature between 500 °C and 900 °C. Morphology studies show that the hard carbon is very porous porous with interconnected porous network. X-ray diffraction and Raman spectroscopic analysis show that the carbon materials have disordered carbon structure with large interlayer spacing pf 0.39 nm. The electrochemical characterizations reveal that hard carbon which is prepared at 700 °C (STHC-700) shows the best performance, showing 375 mAh g−1 and 290 mAh g−1, initial discharge and charge capacities, respectively. Specific capacities of about 268 mAh g−1 and 178 mAh g−1 are obtained for WHC-700 material at a current density of 50 and 200 mA g−1, respectively. The sagoe starch produce hard carbon material at moderate pyrolysis temperature with microstructural properties and large interlayer spacing. These properties are contributing for the excellent electrochemical performance as anodes for sodium ion batteries.
In Situ FTIR Study on Organo-Polysulfide Evolution in CNF/Sulfur-Copolymer Cathodes for Li-S Batteries: Effect of Sulfur Chain Length on the Electrochemical Performance
Authors: Rafie Ayda , Kalra Vibha
Published: December 2020

Lithium-Sulfur batteries offer five times more energy density compared to conventional Li-ion batteries. However, there are challenges related to long term cycling of these batteries. Recently, we synthesized a sulfur-rich copolymer/ carbon nanofiber cathode material for Li-S batteries. The formation of a C-S bond in these sulfur-rich copolymers results in the formation of organo-lithium polysulfides (OPs), instead of lithium polysulfides (PS). In the present work, we demonstrate in situ FTIR spectroscopy as a tool to investigate the C-S bond and lithium polysulfide evolution in sulfur-rich copolymer-based Li-S batteries. The copolymer is synthesized using inverse vulcanization reaction, where sulfur powder reacts with a monomer, here 1,3-diisopropenylbenzene (DIB), at high temperatures. In this study, we varied the DIB monomer concentration and three samples with differen sulfur/DIB wt% were synthesized. Figure 1 shows the cyclic voltammetry (CV) obtained using the three different cathodes. As it can be seen from this fugure two reduction peaks at ~2.3 and 2 V represent the formation of higher and lower order Ps and OPs. However, with further increase in DIB concentration, the first reduction peak at ~2.3V disappears. We hypothesize that the disappearance of the first reduction peak can be attributed to the existence of short sulfur chain length. To investigate the hypothesis, an in situ cell consisted of two different cathodes, one cathode with a low (sample 1) and another with a high DIB wt% (sample 2), were built on the FTIR to simultaneously collect IR spectra and CVs. Our results show that the C-S bond located at ~695 cm-1 in sample 1 shifts to higher wavenumbers (~705cm-1) as we discharge the cell. The shift to higher wavenumbers shows that the formation of OPs, strengthens the C-S bonds which originates from having Li, with lower electronegativity (0.98 VS. 2.58), instead of S. However, when we tested the sample 2 cell, the C-S cyclic shift, happens between ~704 to ~706 cm-1, only. The smaller C-S peak shift in sample 2 compared to sample 1 is attributed to the existence of the short chain length sulfur.

Figure 1
Preparation of Artificial SEI Containing LiNxOy on Lithium Metal Anode By Solid-Gas Interface Reaction for Sulfolane Electrolyte
Authors: Iwahara Ryohei , Nara Hiroki , Momma Toshiyuki , Osaka Tetsuya
Published: December 2020

Li-S battery is promising next generation energy storage device, and lithium metal anode is promising electrode due to its low electrochemical potential and high theoretical specific capacity. However, the Li metal anode in Li-S battery has problems such as short circuit by growth of dendrite and low coulombic efficiency by continuous electrolyte decomposition. In past study, it was reported that high concentration sulfolane electrolyte attributed to prevent polysulfide dissolution into electrolyte and suppressed shuttle effect.1) Also, by adding LiNO3 into electrolyte, stable passivation film formed on lithium metal anode, and lithium deposition became rounded shape and dendrite was suppressed, and long life was reported to be achieved.2)3) While LiNO3 does not dissolve much in high concentration sulfolane electrolyte, in this study, in order to achieve the effect of LiNO3 even with high concentration sulfolane electrolyte, artificial SEI including LiNxOy made by solid-gas reaction was examined. Solid-gas reaction is considered to have also the advantage for the mass production.

In order to produce artificial SEI containing LiNxOy on Li metal anode, which is LiNO3-derived component, polished Li foil was exposed to NO2 gas for 1 h. For the purpose of reacting fresh Li metal surface with NO2 gas, surface of Li foil was polished until metallic luster appeared.

Fig. 1 shows XPS spectra (N1s) of polished Li and NO2 exposed Li. Fig. 1 shows the existence of LiNxOy by an exposure to NO2.

Fig. 2 shows charge-discharge curves in Li/Li symmetrical cells. Fig. 2(a) shows charge-discharge curve using the polished Li, and Fig. 2(b) shows the one exposed to NO2. In Fig. 2(a), short circuit was recognized by only 5 cycles of charge and discharge. Contrastingly, analogous voltage profile was obtained for 16 cycles, as shown in Fig. 2(b). In addition, from Fig. 2(b), a larger overvoltage in voltage plateau was confirmed than that in Fig. 2(a). The reason is considered to be that Li electrode surface is covered with artificial SEI composed of inorganic components such as LiNxOy having relatively high ionic resistance. In addition, it was suggested that the artificial SEI improved the morphology of lithium deposition to smoother one from the SEM investigation.

With an exposure to NO2 on Li metal anode, it was confirmed that artificial SEI containing LiNxOy was prepared and contributed to a certain improvement in cycle life in Li/Li symmetrical cell.

Acknowledgement

This work was partly supported by Advanced Low Carbon Technology Research, Development Program Special Priority Research Area “Next-Generation Rechargeable Battery” (ALCA-Spring) from the Japan Science and Technology Agency (JST) (Grant Number JPMJAL1301).

Reference

1) Azusa Nakanishi et al, Phys. Chem. C, 2019, 123, 14229-14238

2) Allen Pei et al, Nano Lett. 2017, 17, 2, 1132-1139

3) Doron Aurbach et al, J. Electrochem. Soc., 2009, 156, A694

Figure 1
Fabrication of High Burn Rate Fuse Strip for Thermal Battery
Authors: Park Tae-Ryong , Kim Kiyeol , Ahn Tae-Young , Cho Jang-Hyeon
Published: December 2020

Thermal batteries are widely used in various military applications such as missiles and torpedoes due to high power output, long shelf-life, and reliability. In order to react quickly to an enemy, quick activation time of the thermal battery is required. In the process of activation, fuse strip transfers heat energy to the heat source of each layer. Therefore, to achieve short activation time, fuse strip with high burn rate is highly needed. However, although there are lots of variables affecting burning rate of fuse strips, such as a combination of fuel and oxidizers, additives and particle size, it's not well-studied yet.

In this study, we fabricated high burn rate fuse strips by applying additives and new oxidizer. Usually, to fabricate fuse strip, Zr and BaCrO4 slurry is deposited onto supporting ceramic paper and then dried. In order to improve burn rate, we additionally applied HDC-M10, NH4HCO3 and PbO into the Zr/BaCrO4 slurry. The retention agent HDC-M10 makes the dispersion solution stable, making the structure of fuse strip uniform. And the blowing agent NH4HCO3 controls the distance between the particle that makes optimal heat transfer path between the Zr and BaCrO4 particles. Also, PbO was chose as the best additional oxidizer among other several oxidizers which has appropriate reactivity, burn rate and heat calories. The mixed slurry was placed on a sheet former and then made into hollow cylindrical shape. The burning rate was then measured by self-made burning rate measurement equipment. As a result, we observed 10 times improved burn rate than previous studies. In addition, the fuse strip was applied to the thermal battery and its test result is also presented in this study.
Patterned GeSn Strip Growth on Si By Sn Self-Catalyzed Method
Authors: Li Chuanbo , Zhao Yue , Zhang Xiaoming , Feng Shuai , Cheng Buwen
Published: December 2020

GeSn has been attracted much attention in recent years due to its direct band characteristic. However, due to the large lattice mismatch and the low solid solubility of Sn in Ge, the growth of GeSn on Si is still a challenge. Thick-layer GeSn alloy have been grown by molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) by applying the low-temperature-grown Ge buffer layer, but there is still high the dislocation density(more than 107cm-2) and it limits its application in optoelectronics. We have reported a simple way to grow the defect-free GeSn alloy strips on Si substrates with the assistance of Sn metal. It can be lateral grown on Si(111) by Sn self-catalyzed method. The GeSn materials are grown in a MBE system with a base pressure of 5 × 10−8 Pa.

Here we will report our recent progress of the growth of GeSn wires and GeSn pattern on pattered substrate. It is found that GeSn materials can be selected grown in the patterned window. The size of wires can be down to 100 nm. We can grow 10x10 GeSn pattern with size of 2um x 2 um and 5 um x 5um. Here we will also discuss the growth mechanism and the impact factors on the growth of GeSn materials. It is found that Sn has an important impact on morphology of the GeSn wires and different depositions and annealing times of Sn will impact their morphology. GeSn alloy strips show a good quality by the TEM micrographs and the SAED patterns. It has an important application in Si based laser and photodetectors.
Impact of Contact Doping on Electrical Characteristics in WSe2 FET
Authors: Matsuzaki Takahiro , Kawanago Takamasa , Oda Shunri
Published: December 2020

Since layered semiconductor tungsten diselenide (WSe2) has no dangling bond and a relatively large band gap, it is expected as a channel material for an application of field effect transistor (FET)[1]. On the other hand, high energy process destroys the crystal structure of the layered semiconductor. In this context, carrier doping by the low energy process is important for improving the electrical characteristics. This study reports that CYTOP (9 wt%) was applied as a doping material on the WSe2 FET for p-type operation by spin coating and the impact of contact doping on the electrical characteristics was investigated. A SiO2 gate dielectric was formed on a heavily-doped p-Si substrate (p+-Si) using thermal oxidation for back-gate structure. Next, a source / drain of Au (40 nm) / Ti (10 nm) was prepared by using photolithography and lift-off. Using a PDMS stamp and a micromanipulator, WSe2, which was mechanically peeled off using Scotch tape, was transferred between the source and drain to fabricate a back-gate WSe2 FET. After measuring the electrical characteristics without CYTOP, CYTOP was applied on the WSe2 FET surface using a spin coating. Then, the electrical characteristics with CYTOP were measured again. In this study, the annealing was performed for 30min at 200 ° C and 250 ° C. Id-Vg characteristics as a function of annealing temperature of the fabricated back gate WSe2 FET are shown in Fig. 1. From the Fig. 1, it can be confirmed that WSe2 FET shows p-type operation. Moreover, it can be confirmed that the drain current increases by applying the CYTOP, while the low drain current was observed without CYTOP. It was found that the drain current was increased with increasing the annealing temperature.

[Acknowledgments]

The authors would like to thank Professor Y. Kawano, Professor T. Hoshii, Professor I. Muneta, Professor K. Kakushima, Professor K. Tsutsui, and Professor H. Wakabayashi of Tokyo Institute of Technology for their continuous support in the experiments. This study was supported by JST CREST (Grant No. JPMJCR16F4) and a JSPS Grant-in-Aid for Scientific Research (C) (Grant No. 20K04616).

[References]

[1] In-Tak Cho et al., Applied Physics Letters 106, 023504 (2015).

Figure 1
(Invited) Printing Optical Materials
Authors: Li Xinhao , Du Huifeng , Liu Zhiguang , Fang Nicholas Xuanlai
Published: December 2020

Will future of smart lighting and window coatings enable energy-efficient cooling in smart buildings? Can printed color converters lead to next generation micro displays with high brightness, sharp image resolution, and ultra‐low power consumption? Recently, exciting new physics of nanoscale optical materials has inspired a series of key explorations to manipulate, store and control the flow of information and energy at unprecedented dimensions. In this talk we will report our recent efforts on controlling light harvesting and conversion process using scalable micro/nanofabrication. These emerging optical materials show promise to a range of important applications, from optical networks and chip-scale photonic sensors to lasers, LEDs, and solar technology.

For example, pixelated color converters are envisioned to achieve full-color high-resolution display through down conversion of blue micro-LEDs. Quantum dots (QDs) are promising narrow-band converters of high quantum efficiency and brightness enabling saturated colors. However, challenges still remain to produce high resolution color-selective patterns compatible with the advanced blue micro-LEDs with pitch and pixel size approaching 1 µm. Here we demonstrate our preliminary study on scalable printing of high-resolution pixelated red and green color converters patterned through projection lithography. We will also discuss potential applications such as high-resolution wide-gamut microdisplay for mixed reality and high speed visible light communication.

In this talk, We will also introduce versatile 3D shape transformations of nanoscale structures by deliberate engineering of the topography-guided stress of gold nanostructures. By using the topography-guided stress equilibrium, rich 3D shape transformation such as buckling, rotation, and twisting of nanostructures is precisely achieved, which can be predicted by our mechanical modeling. Benefiting from the nanoscale 3D twisting features, giant optical chirality is achieved in an intuitively designed 3D pinwheel-like structure, in strong contrast to the achiral 2D precursor without nano-kirigami. The demonstrated nano-kirigami, as well as the exotic 3D nanostructures, could be adopted in broad nanofabrication platforms and could open up new possibilities for the exploration of functional micro-/nanophotonic and mechanical devices.
(Invited) Atomistic Understanding on the Surface of GaAs By Ab Initio Thermodynamics; From Equilibrium Shape to Growth Shape
Authors: Yeu In Won , Hwang Cheol , Choi Jung-Hae
Published: December 2020

The III-V semiconductor nanowires (NWs) have attracted substantial attention as an ideal system for the study on the growth mechanism and electronic device applications. For the precise manipulation of the nanowire growth, understanding on the temperature–pressure (T–P) dependent variation in surface energy and reconstruction which governs the anisotropic interaction between vapor sources and crystal solids is crucial. Unfortunately, the quantitative values of the variation in surface energy cannot be obtained only using the conventional electronic structure calculation. To overcome this difficulty, we have developed a reliable ab initio thermodynamic method by which the T–P dependent surface energy is predicted from the atomic-scale calculations on: surface reconstructions of InAs1; equilibrium crystal shapes of GaAs and InAs2; and anisotropic adsorption and growth conditions of GaAs NW3.

In this talk, we present an ab initio thermodynamics approach by combining the atomic-scale calculation with the thermodynamic treatment to take a step forward in the theoretical modeling on the growth of polar GaAs <111> nanowire by calculating the change in Gibbs free energy during the nucleation and growth process. By comparing the nucleation rate between different stacking sequences, the formation probability of stacking fault or wurtzite segment was quantitatively predicted under arbitrary vapor-phase growth conditions. The predicted T–P dependent probability from atomic-scale calculation is directly comparable to the experiments and remarkably consistent with the available results to date, elucidating the fundamental asymmetric growth mechanism. Our ab initio approach is truly independent of any empirical data, bridging to the experimentally controllable variables. This simulation can be applied to various nanomaterials, including two-dimensional materials as well as other III-V and II-VI NWs, where the precise control of the stacking sequence is significant for their properties.

[1] Yeu et al., Sci. Rep., 2017, 7, 10691

[2] Yeu et al., Sci. Rep., 2019, 9, 1127

[3] Yeu et al., Appl. Surf., Sci., 2019, 497, 143740
Sn2fe-TiOx Composite Prepared By High Energy Ball Milling As an Anode Material for Li-Ion Batteries
Authors: Baek Mark , Kim Jae-Hun
Published: December 2020

Recently, as portable electronic devices and electric vehicles have been developed, the market needs for energy storage systems are rapidly increasing. Rechargeable Li-ion batteries (LIBs) are representative energy storage devices due to its long cycle life, high energy density, and reasonable cost. To meet the demand for long-lasting batteries, the energy density, which is determined by operating voltage and electrode capacities, should be increased. Therefore, many researchers have been developing high-capacity electrode materials. Currently, carbon-based materials are the most widely used anode materials because of their low operating voltage, moderate capacity, and excellent cycle performance. But, its relatively low capacity (372 mAh g–1 for LiC6 phase after full lithiation) is a limiting factor to meet current energy demands. In order to solve this problem, many researchers have investigated replacements and Li-alloy based materials such Si, Sn and Ge have attracted great attention because of their high theoretical capacity. Among them, Sn-based materials (theoretical capacity: 993 mAh g–1 for Li4.4Sn phase) are one of the most attractive anode materials for high-capacity LIBs. However, commercialization of alloying materials with Li is limited due to the poor cycle performance. When Li is inserted and extracted into/from the electrode materials during charging/discharging, they suffer from rapid capacity fading because of volume change and pulverization of the active materials. In 2007, a Japanese company showed the possibility for solving this problem. SONY released the Nexelion battery which consisted of Sn-Co-C anode materials. This revealed that Sn-based materials have still a potential for widespread commercialization. In this study, we designed and synthesized Sn2Fe@TiOx composites as high-capacity anode materials by high energy mechanical milling. First, tin oxide (SnO), titanium (Ti) and iron (Fe) powders were ball-milled together. During the milling process, SnO was reduced to Sn by Ti and remaining Sn was combined with Fe. As a result, a Sn2Fe-TiOx composite was synthesized. To improve cycling stability, heat treatment and carbon incorporation were employed. Materials and electrochemical characterization were performed to analyze the synthesized materials for LIB anodes.
Production of Germanium Nanoparticles Via Laser Pyrolysis for Anode Materials of Lithium-Ion Batteries and Sodium-Ion Batteries
Authors: Kim Tae-Hee , Choi Sinho , Song Hyun-Kon , Kim Seongbeom
Published: December 2020

Germanium nanoparticles were synthesized and subjected to study as anode materials for lithium ion batteries and sodium ion batteries. Laser pyrolysis of GeH4 was used to produce germanium nanoparticles and the average diameter of these nanoparticles was easily controlled by regulating sensitizer gas flow rates during the process. 60 and 10 nm diameter nanoparticles were synthesized and micron-size powder was purchased and these three pure germanium powder samples were tested as the anode materials of lithium ion batteries and sodium ion batteries in terms of cycle retention, long term cycles and the kinetics of reactions. Experimental results showed that the smallest powder sample which is synthesized, average 10 nm, exhibited excellent performances in both kinds of batteries. According to the results, the characteristics of batteries improved as the size of germanium powder decreased consistently. Pure germanium was thoroughly investigated as an anode of metal-ion batteries with regard to its powder size. The experimental data and synthesis approach of germanium nanoparticles suggested in this research would be a good example for the utilization of elemental germanium in high performance batteries.
Tackling the Development of Rechargeable Calcium Batteries: The CARBAT Project
Authors: Palacin M. , Black Ashley , Tchitchekova Deyana S. , Johansson Patrik , Araujo Rafael B. , Aren Fabian , Arroyo-de Dompablo Elena , Torres Arturo , Tortajada José , Luque Javier , Wuersig Andreas , Bremes Hans G
Published: December 2020

While the cost of the state-of-the-art electrochemical energy storage technology, the Li-ion battery (LIB), has been reduced by 8% at the pack level annually during the last decade (1), it is nowreaching its fundamental limits in terms of energy density. Furthermore, the risk of limited lithium supply and associated cost increases cannot be ignored. Therefore, new sustainable battery chemistries must be developed. Calcium-based rechargeable batteries are proposed to help solving some of the Grand Challenges our modern society is facing: pollution, oil-dependency, and climate change.

Batteries based on Ca have promise of leap-frog increase in energy densities and are especially attractive as Ca is the 5th most abundant element in the Earth’s crust and can indeed be used as a metallic anode with conventional wide potential window electrolytes (2,3). The CARBAT project builds on this breakthrough and its main objective is to achieve proof-of-concept for a Ca anode rechargeable battery. CARBAT combines scientific efforts of computational screening, solid-state and coordination chemistry, materials science, electrochemistry, and battery engineering, and apply these to: (i) develop cathode active materials operating at 4 V and with capacities of 200-300 mAh/g, (ii) optimize electrolyte formulations for fast Ca2+ transport (>1 mS/cm), and finally (iii) assemble a 100 mAh cell demonstrator. All developed materials and cells are validated and benchmarked vs. state-of-the-art LIB technology, both in terms of performance and sustainability indicators.

(1) Nykvist, B.; Nilsson, M. Nat. Clim. Change, 2015, 5, 329.

(2) Muldoon, J. Chem. Rev., 2014, 114, 11683.

(3) Ponrouch, A.; Frontera, C.; Barde, F.; Palacin, M.R. Nat. Mater., 2016, 15, 169.
(Invited) Electrode-Electrolyte Design for Rechargeable Air-Batteries
Authors: Lu Yi-Chun
Published: December 2020

Rechargeable metal-air batteries have attracted intensive research attentions owing to their high gravimetric energy density. However, they suffer from poor cycle life, low round-trip efficiency and low practical energy density. The development of stable and reversible metal-air chemistries requires fundamental understanding on how solvent and salt/additives affect the reaction mechanism and mediation processes. In this presentation, we combine in situ/operando spectroscopy/analytical techniques (online electrochemical mass spectrometry, isotopic labeling and UV-Vis spectroscopy) to reveal the reaction and degradation mechanism of oxygen reduction and oxygen evolution reactions in rechargeable metal-oxygen batteries. We will discuss the role of redox mediator, electrolyte structure-function relationship, and materials design strategies in addressing air-battery degradation.

Acknowledgment. This work is supported by a grant from Research Grants Council (RGC) of the Hong Kong Special Administrative Region under CUHK14307919.
(Invited) A Biomimetic Superoxide Disproportionation Catalyst for Anti-Aging Lithium-Oxygen Batteries
Authors: Hwang Chihyun , Song Hyun-Kon
Published: December 2020

Reactive oxygen species or superoxide (O2
-) to damage or age biological cells is generated during metabolic pathways using oxygen as an electron acceptor in biological systems. Superoxide dismutase (SOD) protects cells from the superoxide-triggered apoptosis by converting superoxide to oxygen and peroxide. Lithium-oxygen battery (LOB) cells have the same aging problems caused by superoxide-triggered side reactions. We transplanted the function of SOD of biological systems into LOB cells. Malonic acid-decorated fullerene (MA-C60) was used as a superoxide disproportionation chemo-catalyst mimicking the function of SOD. As expected, MA-C60 as the superoxide scavenger improved capacity retention along charge/discharge cycles successfully. A LOB cell that failed to provide a meaningful capacity just after several cycles at high current (0.5 mA cm-2) with 0.5 mAh cm-2 cut-off survived up to 50 cycles after MA-C60 was introduced to electrolyte. Moreover, the SOD-mimetic catalyst increased capacity: e.g., more than six-fold increase at 0.2 mA cm-2. Experimentally observed toroidal morphology of the final discharge product of oxygen reduction (Li2O2) and density functional theory calculation confirmed that the solution mechanism of Li2O2 formation, more beneficial than the surface mechanism from the capacity-gain standpoint, was preferred in the presence of MA-C60.
(Invited) Lithium Electrode Protection for Ultra-High Energy and Long Cycle Life Batteries
Authors: Mikhaylik Yuriy , Kovalev Igor , Scordilis-Kelley Charlie , Liao Lily , Laramie Michael , Schoop Urs , Kelley Tracy
Published: December 2020

Sion Power will present breakthrough technology leading to the highest combination of specific energy and cycle life. In the core of this transformational energy storage solution is a protected metallic lithium anode with several levels of physical and chemical protection as well as surface protection of the positive electrode. Protection of negative and positive electrodes offers wide spectra of cell designs from specific energies of 620 Wh/kg at 270 cycles to 420 Wh/kg and cycle life exceeding 800 cycles. The presentation will discuss Sion Power’s technology approaches and the current state of energy density, cycle life, rate capability, area surface resistance, low-temperature performance, and thermal stability of Licerion® batteries.
Role of Discharge-Product Morphology and Formation Rates in Li–O2 Battery Performance
Authors: Torayev Amangeldi , Monroe Charles W.
Published: December 2020

Lithium–oxygen batteries have unprecedented theoretical capacity. Achieving the theoretical capacity in practice remains a challenge – even during low-power operation – because of higher-order phenomena that accompany the formation of discharge products, such as surface passivation and clogging of the cathode’s pores. In the last few years, Li–O2 battery research has moved towards systems that preferentially form large discharge-product particles, which can be achieved by using high-donicity electrolytes and including mediators as additives.1 In this study we examine the implications of discharge-product growth and morphology on performance using numerical simulations.

A continuum model is developed which incorporates multicomponent mass transfer2 described by Onsager-Stefan-Maxwell laws. Including more details about liquid-phase transport is particularly important when modelling solution-mediated discharge processes, because the diffusion of soluble reaction intermediates can control the battery’s apparent discharge capacity. Detailed reaction models, which include precipitation and film-growth kinetics are also necessary, to elucidate the competition between discharge-product formation pathways3: thin-film formation can slow interfacial reaction kinetics, whereas pore clogging raises overpotentials by hindering the transport of reactive species.

Large discharge products form through a solution-phase mechanism, which is favoured by electrolytes that sustain the presence of an LiO2 intermediate for a relatively long time. These intermediate forms the final Li2O2 discharge product either by electrochemically reacting with a lithium ion or by chemically disproportionating, thereby contributing to discharge-product-particle growth. When LiO2 reaction intermediates are long-lived, they can build up in the electrolyte, particularly near the electrode/electrolyte interface. Thus, the system is locally pushed from the dilute into the concentrated regime, and pairwise interactions between species can become significant to device performance.

(1) Torayev, A.; Magusin, P. C. M. M.; Grey, C. P.; Merlet, C.; Franco, A. A. Text Mining Assisted Review of the Literature on Li-O2 Batteries . J. Phys. Mater.
2019, 2, 044004.

(2) Liu, J.; Khaleghi Rahimian, S.; Monroe, C. W. Capacity-Limiting Mechanisms in Li/O2 batteries. Phys. Chem. Chem. Phys.
2016, 18, 22840–22851.

(3) Yin, Y.; Torayev, A.; Gaya, C.; Mammeri, Y.; Franco, A. A. Linking the Performances of Li–O2 Batteries to Discharge Rate and Electrode and Electrolyte Properties through the Nucleation Mechanism of Li 2 O 2. J. Phys. Chem. C
2017, 121, 19577–19585.
Anchored Mediator Enabling Shuttle–Free Redox Mediation in Lithium–Oxygen Batteries
Authors: Ko Youngmin , Park Hyunji , Lee Kyunam , Kim Sung Joo , Park Hyeokjun , Bae Youngjoon , Kim Jihyeon , Park Soo Young , Kwon ji Eon , Kang Kisuk
Published: December 2020

Redox mediators (RMs) are considered an effective countermeasure to reduce the large polarization in lithium–oxygen batteries. Nevertheless, achieving sufficient enhancement of the cyclability is limited by the trade–offs of freely mobile RMs, which are beneficial for charge transport but also trigger the shuttling phenomenon. Here, we successfully decoupled the charge–carrying redox property of RMs and shuttling phenomenon by anchoring the RMs in polymer form, where physical RM migration was replaced by charge transfer along polymer chains. Using a model system of a polymer, PTMA (2,2,6,6–tetramethyl–1–piperidinyloxy–4–yl methacrylate), based on the well–known RM tetramethylpiperidinyloxyl (TEMPO), it is demonstrated that PTMA is capable of functioning as a stationary RM, preserving the redox activity of TEMPO. The efficiency of RM–mediated Li2O2 decomposition remains remarkably stable without the consumption of oxidized RMs or degradation of the lithium anode, resulting in marked improvement of the performance of the lithium–oxygen cell.
(Invited) Advanced Intermediate Temperature Na-Metal Halide Batteries for Grid Applications
Authors: Li Guosheng
Published: December 2020

Developing battery systems that are inexpensive, enduring, and safe is essential for integrating renewable energy sources such as solar and wind power into the electricity grid and providing valuable grid services such as frequency regulation, peak shaving, and arbitrage. In this regard, Na-based batteries are promising candidates because they use naturally abundant sodium (Na) as the charge carrier, which can potentially reduce the materials cost and support multiple energy storage applications. Among various Na-based batteries developed to date, thorough investigations have been done on high-temperature (~300°C) Na-metal halide (Na-MH) batteries, which offer long cycle life and superior safety. In particular, the tubular sodium-nickel chloride (Na-NiCl2 or Zebra) battery has been commercialized and found wide application in the telecom and oil/gas industries. However, the high operating temperature and cost of the Zebra battery has hindered its further market penetration. Recently, the research of Na-MH battery has been focusing on the development of battery technologies operated at intermediate temperature (< 200oC), which has several advantages including simple cell architectures, improved thermal management, lower operating temperature, and lower manufacturing cost over high temperature Na based batteries. Here, we will introduce the mechanism of battery degradation, the development of advanced low-cost cathode materials, long-term cycle results, and the current status and prospects of scale up this promising battery technology.
(Invited) Bottom-up Growth of Lithium in Three–Dimensional Porous Framework Electrodes
Authors: Lee Jong-Won
Published: December 2020

The Li metal anode has attracted much attention, because of its high specific capacity and low electrochemical potential. However, its commercial viability is hindered by the uncontrollable growth of Li dendrites as well as large volume changes over battery cycling. Li storage in three-dimensional (3D) porous framework electrodes of metals and carbon is believed to be effective for resolving those problems with 2D Li metal. However, 3D framework electrodes still suffer from uneven Li plating–stripping: during Li plating, Li preferentially nucleates and grows on top of the framework electrode (facing the separator) because the ionic resistance of electrolyte-filled pores inhibits the migration of Li+ deep into the electrode bottom (facing the current collector). The so-called “top growth” becomes severe in the presence of any protrusions or roughness on the top surface due to the concentrated Li+ flux. In contrast to the general expectations, therefore, the 3D framework electrodes tend to exhibit poor cycling stability and early cell failure. Herein, we present a combined modeling and experimental study showing the manipulation of the Li plating behavior in the 3D framework electrode via interfacial activity tuning. Based on the understanding of the multiple reaction kinetics in the porous framework electrode, we propose an interfacial activity gradient (IAG) design as an effective approach to enable the “bottom-up growth” of Li even without rigorous optimization of porous structures. The Li plating behaviors are theoretically studied on a “model” architecture via transmission line modeling and are experimentally proved. The theoretical and experimental results are in accord with each other, indicating that the IAG design enables the bottom-up growth of Li within the 3D framework electrode, while suppressing the top growth. The IAG electrode exhibits the outstanding improvement in morphological stability and electrochemical reversibility as compared with the conventional framework electrode with uniform interfacial activity.
(Invited) Beyond Dendrites, Cycling Li-Metal at High Current Density
Authors: Wachsman Eric
Published: December 2020

Solid-state Li-batteries are a transformational and intrinsically safe energy storage solution. However, progress has been limited by high solid-solid interfacial impedance and reports of Li-dendrites and corresponding “critical current density”. By surface modification to enable Li-metal wetting and fabricating tailored 3D microstructures using scalable ceramic fabrication techniques we have been able to overcome these limitations achieving 10 mA/cm2 room temperature Li-cycling. Results for Li-metal anode/garnet-electrolyte based batteries with different cathode chemistries will be presented.
Liquid Metal Coating for Improving Li-Anode Cyclability
Authors: Koul Supriya , Morita Yoshiyuki , Ogasa Hiroshi , Fujiwara Yoshiya , Kushima Akihiro
Published: December 2020

Lithium metal is a promising anode material for Li-ion batteries because of its high specific capacity and negative electrochemical potential. However, there are two major challenges that need to be overcome before it can be used in practical applications: 1) electrolyte consumption and 2) dendrite. Lithium being thermodynamically reactive, it decomposes the electrolyte in contact. The dendrite causes short circuit in the battery creating safety issues, and the detachment of the dendrite from the electrode leads to irreversible capacity loss. The exposure of fresh lithium surface associated with the chipping action leads to the further decomposition of the electrolyte.

In this work, we propose a liquid metal (LM) as a semi-solid liquid interface (SSLI) layer to uniformly deposit Li and protect it from direct contact with the electrolyte. Ga-Sn-In alloy, which is in a liquid state at room temperature, was dispersed on a Li metal or directly on a copper current collector as a SSLI layer. Elements in the LM alloy with Li to form a “solid” layer. It is energetically favorable for Li to alloy with these elements than to plate on the film. This high “wettability” of the film against Li promote the uniform deposition and suppresses the nucleation of the dendrites. It will also prevent Li from directly contacting the electrolyte to mitigate undesired chemical reactions.

The effect of LM coating was verified using a Li-Li symmetric cell. The cells without LM failed only after few cycles. The huge increase in the voltage corresponds to significant growth of SEI on the lithium electrode. On the other hand, the cell with LM coating was able to cycle for 100 cycles. A full-cell test using LiNi1/3Co1/3Mn1/3O2 cathode with copper current collector without excess Li was also tested. The result showed much improvement in the cycle lifetime with the LM coating. Scanning Electron Microscopy analysis of the coating layer was performed after the battery cycle test to confirm the ability of the LM coating to reduce the formation of dendrite at the surface.

Figure caption
: SEM micrographs of (A) Cu current collector and (B) the surface after battery cycle test for with and without LM coating. Smooth LM coating was achieved to reduce the surface roughness on the Cu film, and the Li dendrite formation on the surface was reduced by the LM coating.

Figure 1