bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel NaxMO2 (M = transition metal) Cathode Material for Sodium-Ion Batteries: Insight from the Synergetic Effect of Multi-Metal Substitution
Authors: Li Jinke , He Xin , Wang Jun , Li Jie
Published: February 2020

Sodium-ion batteries (SIBs), as a highly promising alternative to its counterpart lithium-ion batteries (LIBs), have attracted increasing attentions due to the low-cost and abundant sodium resources, as well as the compatibility of aluminum current collectors in anode. Due to the heavier atom and larger size of Na atom compared with Li atom, the energy density of SIBs is generally lower than that of LIBs. As a result, the main application area for SIBs would be the large energy storage systems, where cost is the crucial consideration [1].

Currently, to obtain cathode materials with good performance is a main challenge up in SIBs field, because of the relatively large size and slow diffusion of Na+. Several kinds of materials, such as layered transition metal oxides, tunnel-type oxides, phosphates, fluorides, organic compounds, Prussian blue and its analogues, have been proposed as the cathode material for SIBs [2]. Among them, sodium manganese layered oxides NaxMnO2 emerge as the most promising ones as they generally have relatively high theoretical capacity, 2D diffusion space for sodium ions and can be easily synthesized. However, NaxMnO2 still suffer from the obstacles, i.e. the serious capacity fading and bad rate performance because of ‘Jahn-Teller effect’ of Mn3+, and the low energy density as a consequence of the low voltage plateau of Mn3+/Mn4+ redox couple. Substitution Mn with other transition metal elements can be an effective way to overcome these problems [3].

In this work, the double metal (Cu and Mg) substitution is applied to enhance the electrochemical performance of P2-type Na0.67MnO2. The idea is to combine the advantage of inactive Mg ions (enhancing the stability) and active Cu ions (high voltage plateau of Cu2+/Cu3+) to improve electrochemical performance of the material. Compare to the un-substituted and single substituted materials, the co-substituted materials exhibits superior electrochemical performance, it can deliver the initial discharge capacity of 85 mAh g-1 at 180 mA g-1 with capacity retention of 93% after 500 cycles. Besides, Neutron diffraction, X-ray Absorption Structure (XAS) Spectroscopy and In-situ XRD are combined to obtain its structure information. It is found that the co-substitution of Cu and Mg can effectively suppress the multiple phase transitions during electrochemical process, and the structural stability is largely enhanced.

[1] M. D. Slater, D. Kim, E. Lee, C. S. Johnson, Advanced Functional Materials 2013, 23, 947.

[2] H. Pan, Y.-S. Hu, L. Chen, Energy & Environmental Science 2013, 6, 2338.

[3] J.-Y. Hwang, S.-T. Myung, Y.-K. Sun, Chemical Society Reviews 2017.
Design of New Cathode Materials for K-Ion Batteries
Authors: Kim Haegyeom , Kim Jae Chul , Seo Dong-Hwa , Bo Shou-Hang , Ceder Gerbrand
Published: February 2020

Li-ion batteries (LIBs) have succeeded in powering small portable electric devices and are currently expanding to large scale applications (i. e. electric vehicles and grid-level energy storage systems) but it is debatable whether the lithium reserve can meet the increasing demands on the emerging large scale applications. Thus, K-ion batteries (KIBs) and Na-ion batteries (NIBs) are considered alternative energy storage systems due to the natural abundance of K and Na reserve. KIB technology is particularly interesting because K has a lower standard redox potential than Na in non-aqueous carbonate-based electrolytes that are commonly used for NIBs.1-3 It indicates that KIBs can potentially have a higher cell voltage than NIBs when the cathode materials provide the same working voltage as their analogues in Na system. More importantly, graphite, which is a standard anode for LIBs, cannot reversibly intercalate Na ions, thus NIBs require expensive hard carbon anodes. On the other hand, graphite can store and release K ions reversibly, which in fact sparks research interest in KIBs.3,4

The discovery of novel positive electrodes is a critical step toward realizing KIBs. In this work, we develop new cathode materials with layered-structure (i. e. KxTMO2, TM = Co and Mn)5, 6 for KIBs and investigate K-storage properties and mechanism in them by in-situ diffraction and electrochemical characterization combined with theoretical first-principles calculations. Here, we also found that the alkali ion species significantly affect electrochemical properties in layered transition metal oxides. When the size of alkali ion increases (Li+ < Na+ < K+), the voltage curves become more sloped. This is because the formation energy of layered compounds changes more significantly according to K concentrations in K
x
TMO2 due to the stronger interaction between K+-K+ than Na and Li systems. It can deteriorate the specific capacity and operating voltage, and thus energy density. Therefore, it is important to design novel electrode materials that can minimize the interaction between K ions. This presentation will also provide a good guideline how to design electrode materials for KIBs.

References

Eftekhari, A. et al. Potassium Secondary Batteries. ACS Appl. Mater. Sci., 9, 4404. (2016).

Marcus, Y. Thermodynamic functions of transfer of single ions from water to non-aqueous and mixed solvents: Part 3 - Standard potentials of selected electrodes. Pure and Applied Chemistry 57, 1129. (1985).

Komaba, S. et al. Potassium intercalation into graphite to realize high-voltage/high-power potassium-ion batteries and potassium-ion capacitors. Electrochem. Commun. 60, 172. (2015).

Jian, Z., et al. Carbon Electrodes for K-Ion Batteries. J. Am. Chem. Soc. 137, 11566. (2015).

Kim, H. et al. K-Ion Batteries Based on a P2-Type K0.6CoO2 Cathode. Adv. Energy Mater. 7, 1700098. (2017)

Kim, H. et al. Investigation of potassium storage in layered P3-type K0.5MnO2 cathode. Adv. Mater. 29, 1702480 (2017)
High-Performance P2-Type Na0.67Fe0.15Mn0.6Ni0.2Al0.05O2 Cathode Material for Na-Ion Batteries
Authors: Tang Yun , Zhou Min , Wang Kangli , Jiang Kai
Published: February 2020

Li-ion batteries are considered to be most promising candidate for grid-scale energy storage in terms of their high energy density and long cycle life; however, their insuffcient lithium resources and high cost of Li might restrict their large-scale application. Based on the abundance and accessibility of Na and its similar electrochemistry to the well-established LIB technology, Na-ion batteries (NIBs) can be the best alternative to lithium-ion batteries. Among various cathode materials, layered oxides have attracted extensive attention owing to their simple structures, high capacities, and ease of synthesis[1]. Herein, we report a new spherical electrode material P2-Na0.67Fe0.15Mn0.6Ni0.2Al0.05O2, successfully prepared by spray drying method. The performance was significantly improved by partial substitution of Ni with electrochemically inactive Al (content of %5). It exhibits a high capacity of 224 mAh g-1 with good capacity retention. This new positive electrode material is potentially utilized for the NIBs made from only earth-abundant elements[2].

[1] Ortiz-Vitoriano, N., Drewett, N. E., Gonzalo, E., & Rojo, T. (2017). High performance manganese-based layered oxide cathodes: overcoming the challenges of sodium ion batteries. Energy & Environmental Science, 10(5), 1051-1074.

[2] Yabuuchi, N., Kajiyama, M., Iwatate, J., Nishikawa, H., Hitomi, S., Okuyama, R., ... & Komaba, S. (2012). P2-type Nax [Fe1/2Mn1/2]O2made from earth-abundant elements for rechargeable Na batteries. Nature materials, 11(6), 512-517.

Figure 1
Unraveling the Inner-Workings of Lithium Transition Metal Oxyflourides Using DFT-Based Cluster Expansion Method
Authors: Chang Jin Hyun , Loftager Simon , Garcia Lastra Juan Maria , Vegge Tejs
Published: February 2020

Lithium transition metal oxyfluoride is one of the most promising cathode materials that can achieve a two- to three-fold increase in the capacity of the Li-ion batteries compared to the current state-of-the-art [1,2]. Consequently, transition metal oxyfluorides are attracting much interest for both Li-ion and beyond Li-ion batteries in recent years. The mixed-anion compounds such as Li2VO2F and Li2CrO2F offer improved capacity, higher voltage and good conductivity compared to their transition metal oxide counterparts. However, one of the key bottlenecks that prevent the large-scale commercialization of the batteries with transition metal oxyfluorides is the poor cyclability [3]. Understanding the structural, mechanical and electrochemical properties of the transition metal oxyfluorides is, therefore, a crucial step in the further development of such technology. The first-principles modeling is known to be a valuable tool that can accurately predict such properties of material once its atomic arrangements are known. In the case of transition metal oxyfluorides, the exact atomic arrangements, particularly at different lithiation levels, are unknown. Furthermore, the number of possible atomic arrangements to be explored is prohibitively high, which are often described with the term “combinatorial explosion” [4]. In this work, we present a DFT-based cluster expansion method [5,6] which enables one to determine the correlation between the atomic arrangements and their formation energies. The simulation results not only show a good agreement with the reported experimental observations but also provide a deeper insight on the inner-workings of the materials that lead to the observed properties.

Acknowledgement: This research was funded by the “LiRichFCC” (“A new class of powerful materials for electrochemical energy storage: Lithium-rich oxyfluorides with cubic dense packing”), FET-Open call of the European Union Horizon 2020 program under the contract No. 711792.

1. Chen et al., Adv. Energy Mater., 5, 1–7 (2015).

2. Chen et al., RSC Adv., 6, 65112–65118 (2016).

3. Ren et al., Adv. Sci., 2, 1500128 (2015).

4. S. Morgan, G. L. W. Hart, and R. W. Forcade, Comput. Mater. Sci., 136, 144–149 (2017).

5. M. Sanchez, F. Ducastelle, and D. Gratias, Phys. A, 128, 334–350 (1984).

6. D. de Fontaine, Solid State Phys., 47, 33–176 (1994).
High-Capacity Silicon-Carbon Anodes Enabled By Dispersing Nano Silicon Onto Natural Graphite for Lithium Ion Batteries
Authors: Wu Chang-En , Wu Nae-Lih
Published: February 2020

Research on lithium ion batteries has attracted massive attention due to the development of electrical vehicles and portable devices as well as grid energy storage. Pursuit for higher capacity and better cycle life become crucial issue for lithium ion battery anode material. Among all the anode materials, silicon is one of the most promising candidate due to its high theoretical specific capacity (around 3579mAh/g). Graphite, which is the stae-of-the-art commercialized anode material, is known for its stable performance and high electrical conductivity. In this work, a high-capacity composite anode suitable for large-scale production has been synthesized and characterized by taking advantage of both silicon’s high capacity and graphite’s good stability. In this approach, maintaining good dispersion of nano-Si is a critical requirement, and the effects of different dispersants and polymeric binders, which also serve as carbon precursors, have been investigated. Silicon/carbon/graphite composites exhibit high capacity and better cycle life than simple mixing of silicon and graphite powder have been achieved.

Figure 1
Experimental Study on Mechanical Properties of Graphite Electrodes
Authors: Guo Zhansheng , Liu Chao , Lu Bo , Feng Jiemin
Published: February 2020

Graphite electrode has been widely applied in commercial lithium-ion battery, and the importance of graphite electrode mechanical properties are continually increasing. Understanding basic mechanical properties and interfacial peeling strength of graphite electrode will provide data support and theoretical guidance for increasing the reliability of graphite electrode. In this paper, mechanical properties and interfacial peeling strength of graphite electrodes, including fresh electrode, electrolyte soaked electrode and electrodes with different states of charge (SOC) were investigated respectively by tensile test and peeling test. The tensile test results show that the fracture mode of graphite electrode with full charge is brittle fracture, while the fracture mode of fresh electrode, soaked electrode and electrodes with full discharge is ductile fracture. In addition, the 180 degrees peeling experimental results show that the peeling force between active layer and collector with SOC=100% is higher than the value of graphite electrode with SOC =0% .When the battery discharge is completed, the peeling force between the active layer and collector will decline to slightly lower compared with fresh electrode. Fresh electrode and electrolyte soaked electrode have the similar peeling force.
(Energy Technology Division Graduate Student Award Address sponsored by Bio-Logic) Understanding Crosstalks in Li-Ion Cells
Authors: Xiong Deijun , Ellis Leah , Petibon Remi , Dahn Jeff R
Published: February 2020

When LiNixMnyCo(1-x-y)O2 (NMC)/graphite Li-ion cells are operated at elevated temperature or at a cutoff potential above 4.2 V, electrolyte oxidation becomes increasingly severe leading to gaseous products and other oxidized species. Lithiated graphite and delithiated NMC electrode materials taken from high voltage NMC/graphite full cells were studied individually using the pouch bag method. The results obtained from the pouch bag method show that charged NMC positive electrodes stored at elevated temperature in pouch bags create more gas than the same electrodes stored in pouch full cells at the same temperature. The charged NMC electrodes removed from pouch bags after storage at elevated temperature had larger impedance than those removed from pouch full cells. These two observations show that there are interactions between positive and negative electrodes that limit gas evolution and reduce impedance growth in Li-ion cells. X-ray photoelectron spectroscopy studies were used to eliminate some possible mechanisms responsible for these phenomena.
Capacity Fading Mechanism of Silicon Monoxide As the Anode for Lithium-Ion Batteries
Authors: Zhang Linghong , Qin Yan , Liu Yuzi , Liu Qi , Ren Yang , Lu Wenquan
Published: February 2020

Silicon monoxide (SiO) is a promising next-generation anode material for lithium-ion batteries due to its high gravimetric and volumetric capacity. Comparative to commercially used graphite, silicon monoxide offers 18% increase in volumetric energy density on the cell stack level. Compared to future silicon anode, it offers more stable cycle performance, and is therefore a more practical choice for near world applications. Despite the advantages offered by its microstructure and the improved cycle performance enabled by further modification and treatment, the cycle life of silicon monoxide is still far from being good enough in order to be widely used. The primary focus of this work is to obtain better understanding of the major causes of capacity fading and to improve the capacity retention. In order to achieve this, we investigated the electrode composition effects on the capacity retention. Furthermore, the structural effect of silicon monoxide its electrochemical performance is explored.

Acknowledgement

We gratefully acknowledge the support from 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, a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357.
An Approach to Characterize and Clarify Hysteresis Phenomena of Lithium-Silicon Electrodes
Authors: Verbrugge Mark W , Baker Daniel R , Xiao Xingcheng
Published: February 2020

We clarify the hysteretic behavior observed in lithiated silicon electrodes through the development and implementation of a model that describes the main features of the observed voltage hysteresis. Specifically, slow-scan voltammetry at 0.01 mV/s is used to study hysteresis in lithiated silicon thin-film electrodes. At higher scan rates, the curves U(x), where U is voltage and x is state of charge, depend on scan rate, but no difference is seen in the curves when scanning at slow enough rates. For example, no difference is seen at 0.01 mV/s or at 0.005 mV/s, even though the same hysteretic behavior is observed for both scan rates; i.e., the lithiation curve differs significantly from the delithiation curve. The rate of 0.005 mV/s is the slowest that could be measured with state-of-the-art equipment. However, when a lithiating scan at 0.01 mV/s is suddenly set to open circuit conditions, the voltage slowly decays upwards, whereas voltage decays downwards when delithiation is interrupted. From this it is inferred that the rate invariance seen at 0.005 and 0.01 mV/s would have to break down at some lower scan rate, if it could be measured. A semi-empirical model is used to describe many aspects of this behavior based on the assumption of a region of rate invariance, which breaks down at higher scan rates due to transport and kinetic losses, but which also breaks down at slower scan rates due to transients that are observable but remain unexplained.
Effect of Grain Size on the Mechanical, Conductivity and Electrochemical Behavior of Cubic Li7La3Zr2O12
Authors: Wolfenstine Jeffrey
Published: February 2020

In recent years there has been a resurgence in the use of Li metal as an anode, because such use can to lead to rechargeable batteries with higher energy than currently exist. Using a Li anode with a liquid electrolyte can lead to dendrite shorting and flammability issues. To overcome these problems Li-ion conducting solid electrolytes are attracting considerable attention. The major requirements for the solid Li-ion conducting electrolyte are: high Li-ion conductivity, low electronic conductivity, high relative density, chemical/electrochemical stability with the Li anode and cathodes and adequate mechanical properties. The ionic, electrochemical, and mechanical properties of the solid-state electrolyte are in general a function of the microstructure. For a single-phase material the major microstructural variables are porosity and grain size. For a solid-state electrolyte a high relative density is required thus, the major microstructural variable is the grain size. It is the purpose of this presentation to discuss the effect of grain size (5 to 600 mm) on the room temperature total ionic conductivity, hardness, fracture toughness and critical current density (current above where Li plating occurs) for hot-pressed high relative density (>97%) cubic Al-doped Li7La3Zr2O12 with nominal composition of Li6.25Al0.25La3Zr2O12.
Fabrication Characteristics of Thin Solid Composite Electrolyte Film Sheet for Solid-State Lithium Battery
Authors: Ryu Hye-Min , Kim Min-Young , Kim Da-Hye , Jung Ha-Young , Park Sang Jun , Ban Hee-Jung , Kim Yoong-Ahm , Kim Ho-Sung
Published: February 2020

Recently, the use of liquid electrolytes in lithium batteries is prone to cause safety problems such as leakage and gas explosions. The PEO-based solid composite electrolytes have been studied for a possible replacement for liquid electrolytes. However, it results in degradation of mechanical properties and short circuit during cycling at the high temperature above 70°C. Therefore, the thickness of electrolytes is required to be 200㎛ or more. As a method for reducing the thickness, the composite slurry, which was composed of polymer ionic conductor, lithium salts and Garnet-type LLZO, was filled in a porous polyester nonwoven. And then, it was rolled at a constant ratio to have a thickness of 50~100㎛. The morphology of the solid composite electrolyte film sheet was observed using SEM. Furthermore, the electrochemical properties were measured by the AC impedance method and charge/discharge cell test.
New Insights into Anionic Redox Reaction and Performance Degradation of Iron-Based Layered Oxides Cathode Materials for Sodium-Ion Batteries
Authors: Susanto Dieky , Ali Ghulam , Chung Kyung Yoon
Published: February 2020

Sodium ion batteries continue to be of immense interest as potential substitution for lithium-ion battery due to its abundance on earth, contrary to limited source of lithium. The beneficial effect on the cost efficiency will increase if other element in the cathode is also earth abundant materials. Many type of iron based layered oxides such as secondary, tertiary, quaternary layered cathode compound for Na ion batteries have been studied. Most of these studies showed severe loss of cycle performance at high voltage. To improve performance of iron based layered oxides, especially at high voltage region, it is necessary to better understand the redox reaction of Fe3+/Fe4+ during sodium extraction. Thus, O3 type NaFeO2 was synthesized and variety of analysis was conducted such as in-situ synchrotron hard X-ray absorption spectroscopy, ex-situ soft X-ray absorption spectroscopy, and transmission electron spectroscopy.

In situ hard X-ray absorption spectra showed that Fe K-edge doesn’t shift to higher energy during Na extraction. The shift in Fe K-edge is sensitive with oxidation state of Fe that mean Fe3+/Fe4+ redox reaction does not contribute much during electrochemical test. Instead of Fe, the emerging of new peak on the pre-edge of the oxygen K-edge, indicating charge compensation of oxygen during the whole Na extraction/insertion process. Moreover, we directly reveal the limited reversibility of the oxygen redox reaction and correlation of performance degradation with surface degradation of α-NaFeO2 cathode in sodium-ion cells especially at high voltage. These finding provide more deep understanding for future development of iron-based cathode materials for sodium-ion batteries.
Improved Charge/Discharge Performance of LiNi0.8Co0.1Mn0.1O2
positive Electrodes in Solvation-Controlled Electrolyte Solutions for Lithium-Ion Batteries
Authors: Doi Takayuki , Cao Ziyang , Hashinokuchi Michihiro , Inaba Minoru
Published: February 2020

LiNi0.8Co0.1Mn0.1O2 positive-electrodes exhibit high discharge capacities about 200 mAh g-1 by charging up to high potentials of ca. 4.3 V vs. Li/Li+. However, the reversible capacities gradually decrease upon repeated charge/discharge cycling in conventional electrolyte solutions due to 1) their oxidative decomposition at high potentials, 2) cracks of LiNi0.8Co0.1Mn0.1O2 powder, and 3) the phase transition to spinel/rock salt phases. The charge/discharge cycle performance of LiNi0.8Co0.1Mn0.1O2 was greatly improved in highly concentrated LiBF4 propylene carbonate (PC) electrolyte solutions, which have low PC/Li+ molar ratios, such as nearly saturated 7.25 mol kg-1 LiBF4/PC (PC/Li+=1.35). However, the viscosity was much higher than that of conventional electrolyte solutions containing 1 mol dm-3 Li salt. To reduce the viscosity, the highly concentrated LiBF4/PC was diluted with fluorinated linear ether, 1,1,2,2–tetrafluoroethyl 2,2,3,3–tetrafluoropropyl ether (HFE). The dilution with HFE lowered both the viscosity and concentration of LiBF4. A part of PC was replaced with low-viscosity dimethyl carbonate (DMC) to reduce the viscosity further. The charge and discharge properties of LiNi0.8Co0.1Mn0.1O2 were investigated in the resultant electrolyte solutions with Li| LiNi0.8Co0.1Mn0.1O2 half cells. The cells were cycled galvanostatically at 0.1 C (1 C=275 mAh g-1) between 3.0 and 4.3 V at 30oC. In 2.50 mol kg-1 LiBF4/PC+HFE (2:1 by vol., PC/Li+=2.39), the discharge capacity significantly decreased in 50 charge/discharge cycles. On the other hand, in 4.00 mol kg-1 LiBF4/PC+DMC+HFE (1:3:2 by vol., (PC+DMC)/Li+=1.58), 96.5% of the initial discharge capacity (193 mAh g-1) was maintained even at the 50th cycle. The average Coulombic efficiency in the 50 cycles was also high at 99.7 %. Thus, the introduction of DMC into the PC+HFE system improved the charge/discharge cycle performance of LiNi0.8Co0.1Mn0.1O2 positive electrodes.
Aromatic Polyimide Based Composites for Ultrafast and Sustainable Lithium Ion Batteries
Authors: Lyu Hailong , Liu Jiurong , Mahurin Shannon , Dai Sheng , Guo Zhanhu , Sun Xiao-Guang
Published: February 2020

Although lithium-ion batteries based on inorganic cathodes have been utilized in a wide range of applications, they still face challenges such as safety, power density and sustainability. Thus, efforts have been directed to look for alternative, greener and naturally abundant electrode materials for application in lithium ion batteries. As a result, different organic electrodes have been intensively investigated. Among them, aromatic polyimide is a very promising candidate with a theoretical capacity approaching 400 mA h g-1 and a working voltage around 2.5 V vs. Li/Li+. During the discharge process (lithium intake), aromatic polyimide can stepwise accept two electrons, resulting in the formation of a delocalized radical anion and dianion. Currently, there are two common issues preventing the practical application of aromatic polyimide. One is poor rate capability due to their low electronic conductivity and the other one is the rapid capacity fading during cycling due to the dissolution of the active organic cathodes. To overcome the intrinsic electrical insulation of aromatic polyimides and obtain high rate performance, highly conductive carbon additives such as graphene or carbon nanotubes and electron conductive polymers were used to make the polyimide composites. The effect of the type and the amount of conducting agents on the rate performance and long cycling stability of the aromatic polyimide composites based lithium ion batteries will be presented.
Advanced Current Collectors Towards Stable Li Metal Anode
Authors: Wu S
Published: February 2020

Metallic lithium (Li) is a promising anode material for next generation rechargeable batteries. However, the dendrite growth of Li and repeated formation of solid electrolyte interface (SEI) during Li plating and stripping result in low Coulombic efficiency, internal short circuit, and capacity decay, hampering its practical application. In the development of stable Li metal anode, the current collector has been recognized as a critical component to regulate Li plating. In this work, a lithiophilic hybrid structure was synthesized as a current collector for Li metal anodes. The low over-potential for Li nucleation and the uniform Li+ ion flux induced by the current collector enabled effective suppression of the growth of Li dendrites.

As a result, the hybrid current collector achieved a Coulombic efficiency above 95% for 200 cycles at a current density of 1 mA cm-2 and stable repeated Li plating and stripping in a symmetric cell.
The High Performance Silicon Anodes Including New Water Based Binder in Lithium Ion Batteries
Authors: KIM Soo Jung , Kim Nam Seon , Choi Kwang Sik
Published: February 2020

Silicon based negative active material has very high charge capacity and is widely applied to a high capacity battery. However, the silicon based negative active material may expand by about 300% to about 400% during charge and discharge.

Recently much attention has been devoted developing functional binders that can improve adhesion on silicon particle and accommodate substantial volume change during the charge/discharge process to maintain the electrode structure.

The binders for silicon electrodes hold stiff polymeric backbones as like carboxymethyl cellulose (CMC), poly(acrylic acid), and alginate show better electrochemical performance than commercial binders. Despite promising progress, the current research on polymer binders for silicon is still far from the practical application where high mass loading is necessary for the high areal capacity.

Here we report high performance silicon anodes using new water based binder including inorganic binder. This polymer matrix is compatible with lithium ion slurry manufacturing process, and can maintain both electric conductivity and mechanical integrity during the battery operation which results in good stability, rate capability, and cycle-life characteristics at high mass loading (>10mg/cm2).
Ball Milling Synthesis of Silicon Monoxide Anode Materials for Li-Ion Batteries
Authors: Hwang Junesun , Kim Kyungbae , Kim Jae-Hun
Published: February 2020

Li-ion batteries are currently key energy storage devices for various applications such as mobile electronics, electric vehicles, and large-scale energy storage systems. Recently, the global demand for such applications is greatly increasing and in the meantime, high-energy density batteries should be developed to meet the demand. To increase the energy density, the development of high-capacity electrode materials is essential. Currently, graphite is commercially used as anode materials for Li-ion batteries and however, its capacity is limited (theoretical capacity: 372 mAh g­–1). As alternative anode materials, Li-alloy type materials have been intensively investigated to increase the capacity. Among them, Si is one of the most attractive materials because of the high theoretical capacity of 3580 mAh g–1 for Li15Si4 phase. However, it suffers from mechanical degradation caused by large volume change during Li insertion and extraction processes. Recently, silicon monoxide (SiO) materials have attracted great attention due to relatively better cycling stability, which is attributed to the role of oxygen. SiO usually exists in an amorphous form where the oxidation number of Si ranges from 0 to 4. This material can be synthesized by vaporization processes, which is possibly expensive. In this work, SiO materials were prepared by a simple mechanical ball milling process. To improve the electrochemical properties as anodes for Li-ion batteries, carbon incorporation was also performed. The carbon-incorporated SiO materials exhibit the enhanced electrochemical properties.
Strategies to Facilitate the Electron Transfer in Li-O2 Battery Charging Process
Authors: Shen Yue
Published: February 2020

Lithium-oxygen battery has the highest theoretic energy density among all rechargeable batteries. But its discharge product Li2O2 is difficult to be oxidized back in the charge process because it is difficult to transfer electron from Li2O2 to the cathode material (mostly carbon). Here, we introduce 3 strategies to facilitate the electron transfer during charging process: 1. To use redox mediators as redox shuttles between carbon and Li2O2; 2. To use electrolyte which can dissolve Li2O2 (or other peroxide species) so that the dissolved Li2O2 can be oxidized at the carbon surface; 3. To use some highly elastic polymer network to push the Li2O2 to the carbon surface, so that the carbon-Li2O2 contact can be improved. The third strategy was firstly developed in our group and is very suitable to make high loading thick air cathodes with areal capacity > 12 mAh cm-2. These methods were all found to be effective, but not perfect. Especially when the Li metal anode problems are considered. The pros and cons of these strategies will be exhibited, compared and explained. It is also possible to combine these strategies with other advanced cathode architectures and catalysts to further improve the performance. Our study is helpful to design high energy density Li-O2 prototype cells with REAL reversibility.

References:

Sun, D.;Shen, Y.; Zhang, W.; Yu, L.; Yi, Z.; Yin, W.; Wang, D.; Huang, Y.; Wang, J.; Wang, D.; Goodenough, J. B. J. Am. Chem. Soc.
2014, 136, 8941.

Zhang, W.;Shen, Y.; Sun, D.; Huang, Z.; Zhou, J.; Yan, H.; Huang, Y. Nano Energy
2016, 30, 43.

Zhang, W;Shen, Y. ; Sun, D.;Huang, Z.; Huang, Y. Adv. Energy Mater.
2017,1602938

Shen, Y.; Zhang, W.; Chou, S.-L.; Dou, S.-X. Science
2016, 352, 667.
High Volumetric Energy Density Li-Air Battery; Cell Scale Design, Modeling and Simulation
Authors: Lee Heung Chan
Published: February 2020

Ever been higher demands for energy storage systems that can exceed the energy density of current Li-ion battery encourage researchers to investigate new battery chemistries that are beyond the limitation of the current intercalation mechanism based battery chemistry.1–3 Among many candidates for the beyond-intercalation batteries, Li-air battery, also known as Li-O2 battery, got enormous research attention owing to their ultra-high theoretical gravimetric energy density of 3,458 Wh/kg.

Althogh high volumetric energy density is desired for transportation applications due to the space limitation in a vehicle, its volumetric energy density (Wh/L) with actual cell scale evaluation has been rarely discussed.4 It may be due to the theoretical maximum value, 2,040 Wh/L of Li-O2 battery with lithium anode, is not much superior than Li-ion battery with LiCoO2 cathode with carbon anode, 1,940 Wh/L.5

Here, we demonstrate the Li-O2 battery cells perfuming 700 Wh/kg and 610 Wh/L of complete cell level gravimetric and volumetric energy density, respectively, by seamless integration of all the best performing components. To understand transport phenomena inside of the cell and predict maximum performances, specifically designed modeling and simulation was conducted by combining physics of oxygen gas flow into the GDL, dissolution of O2 into the electrolyte, electrochemistry across the whole cell components, and dynamically changing carbon surfaces and porosity by Li2O2 formation.

References

1. Freunberger, S. A. True performance metrics in beyond-intercalation batteries. Nat. Energy
2, 17091 (2017).

2. Lu, J. et al. Aprotic and Aqueous Li–O2 Batteries. Chem. Rev.
114, 5611–5640 (2014).

3. Grande, L. et al. The Lithium/Air Battery: Still an Emerging System or a Practical Reality? Adv. Mater.
27, 784–800 (2015)

4. Gallagher, K. G. et al. Quantifying the promise of lithium-air batteries for electric vehicles. Energy Environ. Sci.
7, 1555–1563 (2014).

5. Lu, Y.-C. et al. Lithium-oxygen batteries: bridging mechanistic understanding and battery performance. Energy Environ. Sci.
6, 750–768 (2013).
Cryogenic Focused Ion Beam Characterization of Alkali Metal Anodes
Authors: Lee Jungwoo Z. , Wynn Thomas Andrew , Alvarado Judith , Hirsh Hayley S , Meng Ying Shirley
Published: February 2020

There is significant effort to enable lithium metal anodes for rechargeable batteries due to its low electrode potential (-3.04 V vs. standard hydrogen electrode) and high theoretical specific capacity (3860 mAhg-1). However, despite nearly a half-century of research efforts, several challenges still exist that prevent widespread adoption, such as the high reactivity with the electrolyte preventing the formation of a stable solid electrolyte interphase (SEI) and lithium metal dendrite formation. While various techniques have been used to characterize lithium-ion batteries, there are limitations to characterizing lithium metal because of its intrinsic high chemical reactivity, low thermal stability, and low atomic number making it prone to contamination and melting, while exhibiting weak scattering characteristics for electrons and x-rays [1].

Recently, cryogenic transition electron microscopy (cryo-TEM) techniques have proven to be powerful for observing the fundamental structure and SEI composition of nanoscale electrochemically deposited lithium metal [2-3]. However, this technique alone is limited to very thin specimens, so cannot be applied to traditional bulk battery materials. Therefore, we explore the ability of cryogenic focused ion beam (cryo-FIB) to mill bulk lithium metal structures while minimizing local heating damage and gallium ion reactions. Using cryo-FIB, we observe notably different features from those of room temperature FIB milled cross-sections of electrochemically deposited lithium metal and solid-state thin-film lithium metal batteries. With this technique we demonstrate the ability to investigate cross-sections of plated lithium metal to observe nucleation, morphology, and density. Further, we demonstrate the ability to cryo-FIB prepare TEM lamellae of solid-state thin-film lithium metal batteries for more comprehensive chemical and structural analyses.

[1] D. Lin et al. “Reviving the lithium metal anode for high-energy batteries,” Nature Nanotechnology. 13 (2017) 194-206.

[2] X. Wang et al. “New insights on the structure of electrochemically deposited lithium metal and its solid electrolyte interphases via cryogenic TEM,” Nano Letters. 10.1021/acs.nanolett.7b03606.

[3] Y. Li et al. “Atomic structure of sensitive battery materials and interfaces revealed by cryo–electron microscopy,” Science. 358 (2017) 506-510.
In Situ Observation of Lithium Dendrite of Different Graphite Electrodes
Authors: Zhu Ruidie , Feng Jiemin , Guo Zhansheng
Published: February 2020

Lithium-ion batteries (LIBs) have some serious safety problems, such as lithium dendrite formation during charging/discharging cycles that may cause internal short-circuiting, fires, and even explosions. A new double-scale in situ experimental setup, which can record all phenomena during the electrochemical testing, was developed. Lithium dendrite growth behavior of commercial LIBs during small-current-density charging at room temperature was observed in situ. The formation, growth, and dissolution of lithium dendrites, and dead lithium residue were all observed and recorded using this new experimental test system. A detailed model of lithium electrodeposition and dissolution processes was proposed. The electrode structures were determined by X-ray diffraction (XRD). The surface morphologies were examined by scanning electron microscopy (SEM). The texture and surface morphology of the graphite active layer affected lithium dendrite initiation as well as its growth processes.
Controllable Synthesis of Low-Platinum Oxygen Reduction Catalysts By Modified Atomic Layer Deposition Process
Authors: Higgins Drew Christopher , Xu John , Kim Yongmin , Orazov Marat , Lee Daniel , Wang Zhaoxuan , Schladt Thoams , Graf Tanja , Jaramillo Thomas F , Prinz Fritz
Published: February 2020

The widespread deployment of polymer electrolyte membrane fuel cells (PEFCs) is still limited by cost and durability challenges that arise from the oxygen reducing cathode catalysts. Current state of the art catalysts are platinum (Pt) or Pt-alloy nanoparticles deposited on high surface area carbon supports. Lowering the Pt loading of PEFC cathodes requires the development of catalysts that combine good oxygen reduction activity and high Pt dispersion (i.e., electrochemically active surface area, ECSA) to achieve sufficient high-power performance [1]. It is therefore highly desirable to develop synthetic techniques that provide careful, atomic level control over the deposition of Pt onto catalyst supports.

In this talk, we will report on a modified atomic layer deposition (ALD) process that provides excellent control over the nucleation and growth of Pt onto different substrate materials. This technique was leveraged to prepare catalysts for the ORR, which were found to show excellent activity that significantly surpasses that of state-of-the-art Pt/C catalysts through rotating disc electrode evaluation. Furthermore, this ALD process provides the ability to deposit Pt on substrates that generally have very poor interactions with Pt precursors, enabling the preparation of uniform, highly dispersed Pt nanoparticles on these materials. Strong catalyst-support interactions resulted from this synthetic technique, with prepared catalysts showing excellent activity and ECSA retention following stability testing, with very little changes observed to the Pt nanoparticle size and morphology. This provides opportunity to use non-traditional catalyst support materials that can potentially overcome corrosion challenges associated with high surface area carbon. Catalyst formulation optimization as well as membrane electrode (MEA) integration is currently underway.

[1] Kongkanand, Mathias, Journal of Physical Chemistry Letters (2016) 7, 1127-1137.
Self-Supported Hierarchical Porous Metallic Aerogels Synthesized Via Spontaneous Methods As High Performance Electrocatalysts
Authors: Liu Wei
Published: February 2020

Metal nanomaterials are one major class of enablers for clean technology. For example, they play vital roles as electrocatalysts in fuel cells and electrochemical sensors. Despite great efforts from world-wide, the commercialization of metal electrocatalysts based devices still meet critical challenges including high cost, insufficient activity, and low durability. Therefore, it is of great interests to explore the factors that influence the electrocatalytic activity and durability of the metallic electrocatalysts, and to develop simple strategies to generate high performance metallic electrocatalysts.

We have developed facile spontaneous methods including one-step spontaneous gelation method in combination with galvanic replacement reaction and fabricated a series of self supported metallic aerogels with extended metal backbone nanostructures of nanowire or nanotubular networks and very high surface area and large porosity.[1-5] In addition, supported metal nanostructure have been also obtained and self-assembled on electrodes.[6,7] These materials were utilized as high performance electrocatalysts in fuel cell anode and cathode reactions and in electrochemical sensors. Our results show that porous structure, metal composition and support material have great influences on the electrocatalytic activity of metal nanomaterials.

Acknowledgements

The authors acknowledge the financial supports from the 100Top Talents Program - Sun Yat-sen University (P.R. China), theEuropean Commission (Brussels) for the Marie Curie Research Fel-lowship for Transfer of Knowledge (No. MTKD-CT-2006-042637)and from the Finnish Cultural Foundation. Financial supportsfrom the Alexander von Humboldt Foundation and the EuropeanResearch Council (ERC-2013-AdG AEROCAT) a gratefully acknowl-edged.

References

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Figure 1
Changes in Proton and Electron Transfer Resistance in Cathode Catalyst Layer of PEM Fuel Cell By Carbon Corrosion
Authors: Cho Seonghun , Park Gu-Gon , Lee Won-Yong , Yim Sung-Dae
Published: February 2020

The structural robustness of the catalyst layer controlled by the morphology of the carbon support is closely related to the durability of the fuel cell. Electrochemical corrosion of the carbon support leads to the structural collapse of the cathode catalyst layer, decreasing the catalyst layer thickness. The collapse of the catalyst layer causes the increase in the oxygen diffusion resistance, which has been accepted as the major mechanism of the performance degradation of the fuel cell by carbon corrosion. However, little attention has been paid on the possibility of the damage of proton and electron pathway in the cathode catalyst layer by carbon corrosion and the resultant performance decay by the pathway damage. In this study, we introduce the fuel cell performance degradation mechanism in terms of the changes in proton and electron transfer resistance that is induced by the structural change of the cathode catalyst layer by carbon corrosion.

Two types of cathode catalyst layer were prepared by adding electrically conductive carbon nanoparticles (Vulcan carbon) and electrically nonconductive silica nanoparticles into the typical Pt/C catalyst layer, respectively, as a model catalyst layer. The cathode catalyst layer consisted of a Pt/C (TEC10E50E) catalyst and long-side chain (Nafion IEC 1.00) ionomer binder. The electrolyte membrane was NRE211 (25 μm). Membrane electrode assemblies (MEAs) were fabricated by decal transfer process and their electrochemical characteristics were measured in a single cell. The accelerated stress test of the carbon corrosion was evaluated by applying a high potential of 1.4 V, and the change of the characteristics of the MEA was confirmed through electrochemical evaluation, before and after the carbon corrosion.

The addition of nanoparticles to the cathode catalyst layer enhanced the structural stability of the catalyst layer regardless of the type of nanoparticles, which led to better durability in the catalyst layers added with nanoparticles after carbon corrosion. After carbon corrosion test, the cathode catalyst layer added with nanoparticles revealed a smaller decrease of catalyst layer thickness and a less increase of ohmic resistance than that of the catalyst layer without the nanoparticles. The different behavior of ohmic resistance change between the catalyst layers with and without the nanoparticles was closely related to the degree of damage in electron pathway in the cathode catalyst layer by carbon corrosion. The degree of proton resistance change in the catalyst layer was also dependent on the presence and the type of nanoparticles added to the catalyst layers.