bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Internal Stress and Oxygen Non-Stoichiometry on Phase Transformations in Battery Cathodes
Authors: Sheth Jay , Liu Dawei , Sheldon Brian W.
Published: February 2020

In battery electrode materials, phase transformations during Li insertion and removal generally lead to volume changes.  These can lead to localized stresses that contribute directly to the degradation of the active material.  We have employed thin V2O5 films as model cathode materials, to systematically investigate relationships between stress, phase transformations, and degradation.  To directly probe the impact of stress, processing conditions were controlled to vary the initial stress state over a wide range (while maintaining similar grain structures).  All of these investigations employed precise in situ stress measurements, along with x-ray diffraction and detailed electron microscopy studies.  The experimental data was then compared to a  thermodynamic model that takes into account the impact of initial and lithiation induced stresses.  The experiments and analysis reveal that stress in the electrode can significantly alter the voltage plateaus associated with two phase equillibria.
LiCoPO4 Based High Energy Li-Ion Cathodes
Authors: Allen Jan L. , Allen Joshua L. , Delp Samuel A. , Wolfenstine Jeff , Jow T. Richard
Published: February 2020

There is an ongoing need for higher energy batteries that operate with the highest abuse tolerance. LiCoPO4 is a 4.8 V cathode material with potentially better abuse tolerance and energy density than the current state of art Li-ion battery chemistries. The intense development of high voltage electrolytes1 and strategies that improve the cycle life2, discharge capacity2 and rate capability3 have increased the interest in this material.

This paper will review our recent efforts on LiCoPO4 electrode development.  We will discuss synthesis methods, transport measurements, thermal properties and the improvements in discharge capacity and cycle life that result from substitutions to LiCoPO4. 

References

1. J.L Allen, J.L. Allen, S.A. Delp, T.R. Jow, ECS Trans. 27, 63-68 (2014).

2. J. L. Allen, T. R. Jow, J. Wolfenstine, J. Power Sources 196, 8656 (2011).

3. J.L. Allen, T. Thompson, J. Sakamoto, C.R. Becker, T.R. Jow and J. Wolfenstine, J. Power Sources 254, 204 (2014).

Figure 1
Thermal Swing Regeneration of Li-Air Battery Cathodes: A Practical Compromise for Prolonged Cyclic Performance
Authors: Kim Jangwoo , Yin Jun , Joo Yong Lak
Published: February 2020

Lithium-air or lithium-oxygen battery, one of the strongest energy storage candidates for extended-range electric vehicles, has theoretical specific energy much greater than that of Li-ion battery. Efforts are underway to overcome the major obstacle of its capacity fades with discharge-charge cycles caused by the formation of the reaction products that are either electrically insulating or electrochemically irreversible. The most certain way to improve the cycle performance is to prevent the unfavorable products from forming from the beginning. However, no one hitherto has discovered a way to completely eliminate them while conducting the discharge-charge cycles. In this work, we present a pathbreaking way of utilizing the unavoidable and undesirable reaction products as catalytic "highways" for oxygen to infiltrate deeper inside the air cathode. Once the cathodes are used and become inactive, we bring them back to life by removing all the residual solvent under mild heat treatment, followed by selectively refilling the pores of the unpassivated carbon with the same electrolyte at room temperature. This so-called thermal swing regeneration process has brought a huge improvement of doubling the cycle life of lithium-air batteries, a better understanding of the intrinsic properties of three-phase interface present to all metal-air system, and provided a new insight towards pulling out full capacity of the system by complete utilization of the available carbon surface in the air cathode.

Figure 1
In Situ Light Microscopy Observation of Sodium Dissolution/Deposition Reaction in Propylene Carbonate-Based Electrolyte
Authors: Yui Yuhki , Hayashi Masahiko , Hayashi Katsuya , Nakamura Jiro
Published: February 2020

Sodium-ion batteries (SIBs) are anticipated as promising alternatives to lithium-ion batteries (LIBs), and many studies have been conducted on electrodes for SIBs using half-cells.  In general, sodium metals are used for the counter electrode of half-cells.  However, there are few reports [1] on sodium dissolution/deposition, knowledge of which an understanding of which is important for advancing the development of SIBs.  In this study, we focused on sodium metal and observed morphologies of sodium dissolution/deposition reactions in propylene carbonate-based electrolyte solution using in situlight microscopy.

Morphologies of sodium depositions were observed by using in-situ light microscopy (Lasertec Corp., ECCS B310).  The semicircular cell for in-situ light microscopy examination was a stack consisting of a sodium sheet as a counter electrode (0.2 mm thick), an electrolyte solution (1 mol/l NaPF6/PC)-soaked polypropylene separator (19 mm in diameter), and a Cu sheet (0.01 mm thick) or sodium sheet (0.2 mm thick) as a working electrode.  Electrochemical measurements were performed by using an automatic galvanostatic discharge-charge system (Hokuto HJ1001SD8) at a constant current of 65 mA/cm2at room temperature.

The sodium deposition reaction on the sodium sheet was observed, and the morphologies were granular and needle-like (not shown here).  Figure 1 shows cross-sectional images of sodium deposition on the Cu sheet, separator, and sodium metal.    The morphologies of sodium deposition showed no difference from that on sodium sheet.  Then, needle-like sodium led to away from the Cu sheet and became “dead sodium”.  This suggests that the sodium metal dissolution/deposition efficiency is low.

 

[1] K. Matsumoto et al., J. Power Sources, 265 (2014) 36.

Figure 1
Fluorinated Alkyl Substituted Sulfones As Electrolytes for High Voltage Lithium-Ion Battery
Authors: Su Chi-Cheung , Hu Libo , Xue Zheng , He Meinan , Xu Kang , Zhang Zhengcheng
Published: February 2020

In an effort to enhance the energy and power density of Li-ion battery technology to facilitate the commercialization of electric vehicles, material researchers have developed new cathode materials with improved specific capacity [1] and operating voltage (5 V vs. Li+/Li).[2] However, the  state-of-the-art electrolyte containing 1.2 M lithium hexafluorophosophate (LiPF6) in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC)/ethyl methyl carbonate (EMC) decomposes at above 4.5 V vs. Li+/Li which prevents the extensive use for the high voltage cathode materials. [3] Thus, the exploration of new electrolytes with elevated voltage stability has been actively pursued. [2]

In this paper, we present a novel electrolyte candidate of fluorinated sulfones for high voltage Li-ion battery. Aided by DFT computation, fluorinated sulfones with various chemical structures (trifluoromethyl)sulfonylethane (FMES), 1-(trifluoromethyl)sulfonylpropane (FMPS) and 2-(trifluoromethyl)sulfonylpropane (FMIS) were designed, synthesized and characterized with analytical methods including NMR, GC-MS and FT-IR and their oxidation stability were examined by a floating method using LiNi0.5Mn1.5O4/Li cell. Sulfone with trifluoromethyl (-CF3) substitution at alpha position possesses enhanced oxidative stability and reduced viscosity as compared to their non-fluorinated counterparts. The alpha-substituted fluorinated sulfones also showed improved wetting ability with PE/PP separators. A facile method for the synthesis of 1,1,1-trifluoro-3-(methylsulfonyl)propane (FPMS), which enabled us to produce  adequate amount of FPMS for electrolyte testing, was also developed. Unlike alpha-substituted fluorinated sulfones, the gamma-substituted fluorinated sulfones resemble the properties of their non-fluorinated ones.

References:

[1] (a) Nyten, A.; Abouimrance, A.; Armand, M.; Gustafsson, T.; Thomas, J. O. Electrochem. Commun., 2005, 7, 156-160. (b) Ellis, B. L.; Makahnoul, R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F. Nat. Mater., 2007, 6, 749-753.

[2] (a) Zhang, Z.; Hu, L.; Wu, H.; Weng, W.; Koh, M.; Redfern, P. C.; Curtiss, L. A.; Amine, K. Energy Environ. Sci., 2013, 6, 1806-1810. (b) Hu, M.; Pang, X.; Zhou, Z. J. Power Sources, 2013, 237, 229-242. (c) Xu, M.; Zhou, L.; Done, Y.; Chen, Y.; Garsuch, A.; Lucht, B. L. J Electrochem. Soc.
2013, 160, A2005-A2013. (d) Von Cresce, A.; Xu, K. ECS Trans., 2012, 41, 17-22. (e) Santhanam, R.; Rambabu, B. J. Power Sources, 2010, 195, 5442-5451.

[3] a) Kunduraciz, M.; Amatucci, G.G. J Electrochem. Soc.
2006, 153, A1345-A1352. (b) Wolfenstine, J.; Aleen, J. J. Power Sources, 2005, 142, 389-390.

Figure 1
Mechanically Robust Sandwich-Structured C@Si@C Nanotube-Based Li-Ion Battery Anodes
Authors: Liu Jinyun , Goodman Matthew D. , Zhang Hui Gang , Epstein Eric S. , Huang Bo , Pan Zeng , Kim Jinwoo , Choi Junhee , Huang Xingjiu , Liu Jinhuai , Li Nan , Hsia K. Jimmy , Dillon Shen J. , Braun Paul V
Published: February 2020

Advanced secondary (rechargeable) batteries require high energy density and high structural stability anodes and cathodes. High volumetric energy density is particularly desirable for micro-electronic devices and portable applications, however it can impact almost any application. In current commercial lithium-ion batteries, carbon-based anodes are dominant; however, their capacity and structural stability are not ideal due to the low theoretical capacity (372 mAh g‒1) and intrinsically fragile structure of carbon. Silicon is a very attractive anode material because of its huge theoretical capacity (~4,200 mAh g‒1). Nevertheless, the solid electrolyte interphase (SEI) formation on Si surface is generally unstable due to the large volume change during lithiation-delithiation (400%), which leads to substantial capacity decay with cycling.

  Here we present an anode design consisting of closed-end Si nanotubes coated with carbon on both sides (C@Si@C). This sandwich-like structure with double-sided carbon coatings provides both good electrical conductivity and effective protection of electrochemically active Si, leading to a stable SEI. Because the C@Si@C nanotube array was fabricated onto a three-dimensional (3D) scaffold, the anode exhibits a considerable energy density.

  Our results show this nanotube array exhibits a capacity of about 2,200 mAh g-1, and a nearly constant Coulombic efficiency of about 98% over 60 cycles. Correspondingly, the volumetric energy density (~750 mAh cm–3) considerably exceeds the volumetric energy density of commercial graphite anodes (~300 mAh cm–3). Through a series of control experiments, we find the C@Si@C nanotube array gives much better capacity and structure stability compared to the Si nanotubes without carbon coatings, the ZnO@C@Si@C nanorods, a Si thin film on Ni foam, and C@Si and Si@C nanotubes. In-situ SEM observations on lithiation-delithiation shows a stable structure evolution of the sandwich nanotube. Through stress and plastic strain modeling, while the plastic strain in the nanotubes increases gently, the one in the nanorods increases dramatically. Since the plastic strain amplitude in the nanorods is significantly higher than that in the nanotubes, in terms of a low-cycle fatigue mechanism of Si during lithiation-delithiation, it is expected that the nanorods would fail with significantly fewer lithiation-delithiation cycles compared to the nanotubes. Our findings show this design of sandwich-structured nanotube array is effective for fabricating anodes with both stable structure retention and high energy density. We believe this strategy is quite general can find application for a large variety of other anode and cathode designs.
Reversible Lithium Storage in Carbon Encapsulated Hollow Silicon Nanospheres
Authors: Ashuri Maziar , He Qianran , Zhang Kan , Emani Satyanarayana , Sawicki Monica , Shamie Jack S , Shaw Leon
Published: February 2020

One of the major challenges associated with the application of silicon as anode material for Li-ion batteries is the huge volume expansion/shrinkage during the lithiation/delithiation process. This volume change can result in the formation of crack in the particles and degrade the capacity. To solve this problem, we report a facile synthesis method which maintains the structural integrity of the material during cycling. Polystyrene beads was used as the templating agent and coated with silica through the sol-gel process. Then, the core was removed in the stepwise heating. Subsequently, the obtained shell was reduced to silicon via the magnesiothermic reduction. The final step is the coating of hollow Si spheres with carbon in the autoclave. SEM, TEM, XRD, FTIR, TGA and Raman were used to investigate the microstructure of the core-shell nanoparticles. Carbon encapsulated hollow spheres were mixed with carbon black, polyacrylic acid (PAA) and N-Methyl-2-pyrrolidone (NMP) to form a slurry. Copper foil as the current collector was covered with the slurry and dried at 120 ºC overnight. Half-cells were fabricated using a Li foil coupled with the carbon encapsulated Si hollow spheres in CR2032 coin cell cases. Charge and discharge were performed in the voltage window of 0.005-1.5 V with different current densities. The highest discharge capacity was about 2000 mAh/g at the first cycle. Cyclic voltammetry (CV) test confirms the reversibility of the reactions in both charge and discharge sections. Impedance spectroscopy measurements verify the decrease in impedance of the battery after cycling.
High Capacity Silicon Electrodes with Nafion As Binders
Authors: Xu Jiagang , Zhang Qinglin , Cheng Yang-Tse
Published: February 2020

Silicon is capable of delivering a high theoretical specific capacity of 3600 mAh/g which is much higher than that of the state-of-the-art graphite based negative electrodes for lithium ion batteries. However, the poor cycle life of silicon electrodes, caused by the large volumetric strain during cycling, limits the commercialization of silicon electrodes. As one of the essential components, the polymeric binder is critical to the performance and durability of lithium ion batteries as it keeps the integrity of electrodes. The binder must be stable as it interacts with the active material and the electrolyte during the life of the battery. In this work, we demonstrate that electrodes consisting of silicon nano particles mixed with commercially available and ion-exchanged Nafion can deliver a high capacity over 2000 mAh/g for 50 cycles. For comparison, the capacity of electrodes made of the same Si nanoparticles mixed with traditional polyvinylidene fluoride (PVDF) faded rapidly. The mechanisms responsible for Nafion’s superior performance as a binder, such as ionic conductivity and stability of the resulting solid-electrolyte interphase, will be reported.
Characterization of Thin and Uniform Carbon Coated Overlithiated Layer Oxide Cathode Material for Lithium Ion Batteries
Authors: Park Kwangjin , Yoon Jaegu , Park Jun-ho , Hong Suk-Gi , Doo Seokgwang , Park Jin-Hwan
Published: February 2020

Thin and uniform carbon coated overlithiated layer oxide (OLO) using 2,3-dihydroxynaphthalene (DN) is prepared. The pristine and DN coated samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). An amorphous nanolayer coating of carbon is obtained on the surface of layered pristine material. The coating layer was confirmed by TEM analysis. The thickness of coating layer was approximately 5 nm, when the content of DN coating was 0.2 wt.%. For optimization of coating condition, the coating weight and the temperature of heat treatment was changed. The 0.1wt% DN coated OLO which was heated at 500oC exhibits the improved electrochemical performance. The initial discharge capacity of 202 mAh·g−1 is obtained at 1C. This capacity is larger of 2% than that of bare OLO. The capacity retention (93.9% at 50th cycle) is also maintained compared to bare OLO (92.3% at 50th cycle). The average voltage drop of coated OLO showed 20mV lower than that of bare sample after 50th cycle. The thin and uniform carbon layer leads to improvement of kinetic and protection of direct contact between cathode and electrolyte.

References

1. N. Yabuuchi, K. Yoshii, S. Myung, I Nakai, S. Komaba, J. Am. Chem. Soc. 2011, 133, 4404-4419

2. T. Kwon, H. Nishihara, Y. Fukura, K. Inde, N. Setoyama, Y. Fukushima, T. Kyotani,

Figure 1
The Transition from Planar to Curved and Flexible Batteries
Authors: McNulty David , Buckley D. Noel , O'Dwyer Colm
Published: February 2020

There is currently an enormous drive in research, development, production and marketing of Li-ion batteries for smartphone, tablets, portable electronics and of course hybrid and full electric vehicles (1-3).  The design of the portable electronics is currently being limited by the requirement to accommodate rigid planar batteries. Capacities can of course be increased, but this increases the bulk design, size and weight of the battery. For future portable devices, particularly wearable technology devices, there will be a need to transition from traditional planar cells to curved and flexible cells (4-6). One approach towards the development of curved and flexible cells is through the development of a sprayable battery process (7-9).

In this work we detail the preparation of sprayable paints using the most commonly used commercial cathode and anode materials, LiCoO2 and graphite respectively as well as a sprayable separator. Initially the component paints were sprayed on to rigid current collectors. The resulting layered cells were tested in split cells to confirm their successful operation. The paints were then applied to curved current collectors leading the transition from a rigid planar cell to a flexible cell. Through detailed electrochemical investigations we compare the electrochemical performance of the layered cells in split cells, and in pouch cells on curved and flexible current collectors. Our approach initially uses commercial cathode and anode materials to confirm the successful operation of non-planar cells. We also investigate the use of a promising alternative cathode material in the form of V2O5 polycrystalline nanorods (poly-NRs) (10). Through galvanostatic cycling and cyclic voltammetry the electrochemical performance of poly-NRs in a full Li-ion cell in both planar and non-planar arrangements is demonstrated.

Acknowledgements

This research was supported through a Science Foundation Ireland Technology Innovation and Development Award under contract no 13/TIDA/E2761.

References

1.         N. Liu, H. Wu, M. T. McDowell, Y. Yao, C. Wang and Y. Cui, Nano Lett, 12, 3315 (2012).

2.         D. McNulty, D. N. Buckley and C. O'Dwyer, J. Power Sources, 267, 831 (2014).

3.         V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach, Energy & Environ Sci, 4, 3243 (2011).

4.         M. Osiak, H. Geaney, E. Armstrong and C. O'Dwyer, J. Mater. Chem. A, 2, 9433 (2014).

5.         J. Ren, Y. Zhang, W. Bai, X. Chen, Z. Zhang, X. Fang, W. Weng, Y. Wang and H. Peng, Angew. Chem. Int. Edit., 53, 7864 (2014).

6.         C. O'Dwyer, NPG Asia Mater, 6, e139 (2014).

7.         Y. Hu and X. Sun, J. Mater. Chem. A, 2, 10712 (2014).

8.         H. Gwon, J. Hong, H. Kim, D.-H. Seo, S. Jeon and K. Kang, Energy & Environ Sci, 7, 538 (2014).

9.         N. Singh, C. Galande, A. Miranda, A. Mathkar, W. Gao, A. L. M. Reddy, A. Vlad and P. M. Ajayan, Sci. Rep., 2, 481 (2012).

10.       D. McNulty, D. Buckley and C. O’Dwyer, J. Electrochem. Soc., 161, A1321 (2014).
A Study on Rate Capacity and Safety of Ionic Liquid-Based Lithium Ion Battery
Authors: Nishimura Takuya , Kojima Katsunori
Published: February 2020

Lithium ion battery (LIB) is expected to be applied to large-format energy storage system and the cell performance with higher safety along with high energy density and high power density is demanded in industry applications. In order to improve the safety performance of LIB, much attention has been paid to an ionic liquid, instead of an organic solvent, as an electrolyte. LIB with the ionic liquid-based electrolyte, however, shows relatively poor rate capability compared to LIB with the organic solvent. Recently, several papers have revealed that LIB with bis(fluorosulfonyl)imide (FSI) anion-based ionic electrolyte shows good rate capability1,2). The reason is because of the reduction of charge transfer resistance between FSI anion-based ionic liquid electrolyte and electrode. The point of further development of the LIB using the ionic liquid-based electrolyte is to achieve both the improvement in the rate capability and safety by optimizing cell design including electrode, separator and others.

 In this study, influence of the electrode design and the nonwoven fabric separator on rate capability of a LIB with N-methyl-N-propylpyrrolidinium (Py13)/FSI-based ionic liquid electrolyte was investigated. The safety behavior of the LIB using Py13/FSI-based ionic liquid electrolyte was also evaluated by the overcharging test and nail penetrating test, comparing with the LIB using organic electrolyte. The rate capability of the LIB using Py13/FSI-based ionic liquid electrolyte was improved by optimizing the electrode design with higher porosity and thinner thickness and by using the nonwoven separator with more than 80 % of porosity. It is suggested that the enhancement of lithium ion mobility in both the porous electrode and the porous separator filled with the ionic liquid electrolyte is more effective to improve the rate capability, comparing the organic electrolyte. As a result of evaluation of the safety behavior, LiNi0.5Mn1.5O4/Li4Ti5O12cell using Py13/FSI-based ionic liquid electrolyte, as compared with the organic electrolyte, exhibited a superior safety performance in the nail penetrating test. The heat generation was also drastically suppressed by the high thermal stability ionic liquid electrolyte. The heat generation was drastically suppressed in comparison with the organic electrolyte due to high thermal stability of the ionic liquid electrolyte.

 References

1) H. Matsumoto, H. Sakaebe, K. Tatsumi, M. Kikuta, E. Ishiko, M. Kono , J. Power Sources., 160, 1308 (2006)

2) T. Sugimoto, M. Kikuta, E. Ishiko, M. Kono, M. Ishikawa, J. Power Sources., 183, 436 (2008)
Improving the Electrochemical Performance of Nanostructured Sn Film Anodes By a Catalytic Top Coat
Authors: Polat Deniz Billur , Bilici Burcin , Keles Ozgul
Published: February 2020

To improve the electrochemical performance of Sn anode, a Cu film with high surface area is used as substrate material. To improve the electrochemical performance of this nanostructured Sn anode, a catalytic material is applied as top coat on the Sn film. The bare and the coated Sn films are tested galvanostatically in half cells with C/12 rate in voltage ranges of 0.2-1.2V. To understand differentiation in their performances, cyclic voltammetry and electrochemical impedance spectroscopy are applied on these samples. The results show that the combination of high surface area and catalytic top coating point to a new approach to improve the long term cycleability and high capacity performance of LIB anodes.   

Keywords: Lithium ion battery, Sn anode, CV, EIS, electrolytic coating.
Effect of Cathode Slurry Composition on the Electrochemical Properties of Li-Ion Batteries
Authors: Dermenci Kamil Burak , Turan Servet , Behm Mårten , Lindbergh Göran
Published: February 2020

The performance difference between commercial and laboratory scale cells remains a problem to be solved. Different way of battery electrode preparation is considered to be the main reason underlying various battery performance. There are three main constituents of active material, conductive additives and binders found in a cathode. Active material acts as a Li+ source and conductive additives are used in order to enhance electronic conductivity. Binders are generally added to keep active material and conductive additives together and on the current collector. In this work, the effect of slurry compositions on electrochemical properties of Li-ion batteries is reported. Slurry preparation with various compositions of LiFePO4 as an active material (76-88%), PVdF as a binder (6-12%) and Super P Carbon as a conductive additive (6-12%) has been studied. Charge-discharge curves and capacity fade of electrodes under varying C-rates are also investigated. Some of electrodes were pressed from selected samples in order to see the effect of pressing on the final performance. Results showed that varying PVdF and carbon content mainly effects charge-discharge characteristics. For unpressed samples, higher amount of PVdF and carbon could result higher maximum specific capacity and lower internal resistance during lithiation and delithiation of positive electrode. Pressing reduces the distance between slurry particles which enhances the conductivity of the prepared cell.
Oxides As Cathode Materials for Mg-Ion Batteries
Authors: Barile Elizabeth C. , Gewirth Andrew A.
Published: February 2020

Magnesium (Mg) batteries have the potential to revolutionize energy storage. Theoretically these batteries far outperform current Li-ion batteries in both volumetric and gravimetric capacities.
[1]
Additionally, Mg is a more earth abundant (13.9% Mg in earth’s crust compared to 7x10-4 % Li) and less expensive alternative ($2700/ton Mg and $64000/ton Li), ideal for automobile electrification and thus transforming society.
[2]

Despite these attractive properties, implementation of Mg-ion batteries has been hindered by several challenges. Most significantly, 1) electrolytes which allow for reversible Mg deposition have limited stability, and 2) reversible intercalation of Mg2+in cathode materials is kinetically slow and often irreversible. Thus, future Mg-ion batteries must incorporate stable high voltage and capacity cathode materials with fast and reversible Mg intercalation kinetics.

Mg battery prototypes have used Chevrel phase cathodes, Mo6S8, and its derivatives.
[3]
These cathodes incorporate a delocalized framework to accommodate the charge and diffusion of hard Mg2+ ions. The multiple Mo ions allow for a diffuse charge network to accommodate intercalated Mg2+ ions. However, Chevrel phase cathodes suffer from low voltages (~1.1 V vs Mg/Mg2+) and only partial reversibility, where the total capacity drops by ~40% after the first discharge cycle.
[4]
For Mg batteries to be realized commercially, the cathode’s voltage and reversibility must be improved.

In this talk we discuss our efforts using transition-metal oxides with open and delocalized structures as cathode materials for Mg-ion batteries. We investigate various bronzes and polyoxometalates, which have known magnesiated forms and high redox potentials. We find that these oxides exhibit reversible electrochemical behavior in various non-aqueous electrolytes and report on our efforts at confining these materials to electrode surfaces.  

               

[1] Yoo, H.; Shterenberg, I.; Gofer, Y.; Gershinsky, G.; Pour, N.; Aurbach D. Energy Environ. Sci.
2013, 6, 2265.

[2] Saha, P.; Jampani, P.; Datta, M.; Okoli, C.; Manivannan, A.; Kumta, P. J. Electrochem.Soc.
2014, 161, A593.

[3] Aurbach, D.; Lu, Z.; Schechter, A.; Gofer, Y.; Gizbar, H.; Turgeman R.; Cohen, Y.; Moshkovich, M.; Levi, E. Nature, 2000, 407, 724.

[4] Saha, P.; Datta, M.; Velikokhatnyi, O.; Manivanna, A.; Alman, D.; Kumta P. Prog. Mater. Sci.
2014, 66, 1.
Advanced Na[Ni0.25Fe0.5Mn0.25]O2/C Cathode / EMS Electrolyte / Fe3O4 Anode for Sodium-Ion Batteries
Authors: Hwang Jang-Yeon , Oh Seung-Min , Myung Seung-Taek , Yoon Chong seung , Lu Jun , Amine Khalil , Sun Yang-Kook
Published: February 2020

Lithium is an attractive battery material because it is the lightest metal, but its resources are concentrated in large quantities mainly in South America with an associated risk of dependence on a single geographic area.1 In addition, the price of lithium-ion batteries is affected by the high cost of their active materials, commonly based on cobalt compounds. As a result, there is an increasing interest worldwide in developing low cost and sustainable energy storage systems that do not use lithium or cobalt. Among them, rechargeable sodium batteries, due to the almost infinite supply of the metal, are the most appealing as immediate alternatives to lithium batteries. Recently reported results2-4 have triggered an increasing industrial and academic interest in sodium-ion batteries operating at room temperature. Pioneering work by Hagenmuller et al. and Yamamoto et al. introduced O3-type NaMO2 (M = Ni, Co, and Fe) in which Na+ could be inserted into a host structure. Since then, interest in developing sodium batteries declined because of the fast development and market domination of lithium-ion batteries. However, recent increasing demands for low-cost energy storage have renewed interest in sodium-based batteries and, accordingly, the O3 type NaMO2 compounds are being revisited as a cathode material due to the facile synthesis and structural stability, including Na-Ni0.5Mn0.5O2, NaCoO2, NaCrO2, NaMnxM1
−
xO2 (M =Co, Ni), Na[Ni1/3Fe1/3O1/3]O2, and NaxVO2. At present, the electrochemical performance of these cathode materials has been limited due to the lack of electrolytes capable of withstanding voltages above 3.9 V versus Na/Na+. In response, we have developed a sodium-ion battery that has an electrolyte of NaClO4 in a mixture of ethyl methanesulfonate electrolyte (EMS) and fluoroethylene carbonate (FEC) additive for increasing the stability and conductivity, along with an anode of carbon-coated Fe3O4 and a cathode of O3-type layered Na[Ni0.25Fe0.5Mn0.25]O2. The electrolyte is a key component if sodium-ion batteries are to become competitive with or surpass lithium-ion batteries. The main requirement is a wide anodic stability window in order to allow complete desodiation of the cathode. A common choice has been 1 M sodium perchlorate in propylene carbonate (NaClO4−PC) with selected additives. For instance, as suggested by Komaba et al., the addition of a small amount of FEC to the PC-based solvent contributes to improved cycleability of sodium batteries, possibly because of a positive effect induced by the fluorination of the anode surfaces.

(1) Scrosati, B.; Garche, J. J. Power Sources 2010, 195, 2419−2430.

(2) Fouassier, C.; Matejka, G.; Reau, J.-M.; Hagenmuller, P. J. Solid State Chem. 1973, 6, 532−537.

(3) Delmas, C.; Fouassier, C.; Hagenmuller, P. Physica B+C 1980, 99,81−85.

(4) Braconnier, J.-J.; Delmas, C.; Fouassier, C.; Hagenmuller, P. Mater. Res. Bull. 1980, 15, 1797−1804.
Surface Coating of 5V Spinel LiNi0.5Mn1.5O4 Cathodes By Carbon Materials for Li-Ion Batteries Applications
Authors: Hwang Taejin , Lee Jieun , Noh Hana , Lee Jeongyeon , Mun Junyoung , Lee Joong-Kee , Choi Wonchang
Published: February 2020

Introduction

As applications of Lithium ion batteries (LIBs) are focused, high energy density active materials are needed. Therefore, LiNi0.5Mn1.5O4(LNMO) is one of the promising active materials for LIBs because of it has high working voltage about 4.7 V and good cyclability. Carbon coating is one of the best methods to prevent surface side reactions of electrolyte. However, oxide cathode materials are usually synthesized at high temperature, so that carbon coating is limited because carbon can be oxidized easily. To overcome this problem, we performed re-oxidized process to make RO-MWCNTs. We expected this can assign resistivity against oxidation to MWCNTs. Continually, RO-MWCNTs are coated on LNMO by solid-state coating method. Several electrochemical tests have performed to identify effects of RO-MWCNTs coating on LNMO powder.

Experimental

To prepare RO-MWCNTs, pristine MWCNTs were reduced at 900℃ for 6 hours under Ar gas which contains 5wt% of H2. Reduced MWCNTs are re-oxidized at 300℃ for 2 hours. As prepared MWCNTs and RO-MWCNTs have coated 1wt% on LNMO by the solid-state coating at Hosokawa. Proportion of coated materials were specified by TGA and EA. Electrode slurry has been made of 96% of active materials, 2% of Denka black, 2% of PVdF in NMP solvent. Total amounts of conductive materials and coated MWCNTs are fixed for 2%. The slurry was casted on Al foil for current collector and assembled with 2032 coin cell.

Results and discussion

Figure 1. shows rate capability test of pristine, MWCNTs coating, RO-MWCNTs coating LNMO samples. C-rates were changed at various rates. According to rate capability test result, RO-MWCNTs coating has improved electrical conductivity of electrode.

Figure 2. shows cyclability test of samples which had been stored at 60℃ oven for 7 days. We could observe RO-MWCNTs coated sample has much better capacity retention than MWCNT coated and pristine samples. We could identify that re-oxidized process have affected MWCNTs to resist against oxidation at high voltage.

Figure 1
Surface Modification of Silicon-Based Alloy Materials for Lithium-Ion Battery Applications
Authors: Yang Hwi Soo , Kim Sang-Hyung , Kim Seon-Kyong , Park Cheol-Ho , Kim Dong-Won
Published: February 2020

Lithium-ion batteries have been considered as a promising power source for electric vehicles and energy storage systems, due to their high energy density and long cycle life.  In order to further increase the energy densities of lithium-ion batteries, it is essential to improve the specific capacity of active electrode materials.  It has been well known that the silicon-based anode materials have an extremely high theoretical capacity.  However, the main problem of silicon-based anode materials is high volume expansion during cycling, which leads to the loss of electrical contacts and poor capacity retention.  To solve these issues, many studies have been carried out in terms of thin film, nanostructure, alloy and composites. The capacity fading is known to be closely related to the interfacial instability of the Si-based electrodes.  In this study, we report synthesis and electrochemical characterization of Si-based alloy materials for high energy density lithium-ion batteries.  Furthermore, we modified their surface to form stable interfacial layer and obtain good capacity retention.  Their interfacial studies and cycling performances are investigated by electrochemical impedance spectroscopy, XPS, FE-SEM, HR-TEM and galvanostatic cycling test.
Atomistic Simulation Studies of the Electrochemical Activity in Nanocrystalline Li2MnO3
Authors: Ngoepe Phuti Esrom , Sayle Thi X T , Sayle Dean C
Published: February 2020

Layered-layered oxide composite cathodes, typically of composition xLi2MnO3·(1−x)LiMO2, have attracted much attention, for essentially doubling the capacity available in the earlier generation of Li-ion batteries based on LiCoO2 [1].  However, their use is currently limited by, amongst others, voltage fade [2]. Hence, further studies on one of the end members of the composites, Li2MnO3, could shed valuable insights on such problems.

Li2MnO3 is known to be electrochemically inactive in the parent bulk form and can be rendered Li-active by leaching Li or Li2O from the structure; these Li-deficient compounds are reported to have high intercalation capacities and good reversibility [3]. Alternatively, when synthesized in a nanocrystalline form, Li2MnO3 has been shown to be electrochemically active, yielding capacities up to 200 mAh/g, and excellent capacity retention over multiple cycles [4].

In the current study simulated amorphisation recrystallisation method [5] is used to nucleate and crystallise ternary nanoparticle of Li2MnO3. Simulations of the charging of Li2MnO3 reveal that the reason nanocrystalline- Li2MnO3 is electrochemically active, in contrast to the parent bulk- Li2MnO3, is because in the nanomaterial the alternating Li planes are held apart by Mn ions, which act as a pseudo ‘point defect scaffold’. The Li ions are then able to diffuse, via a vacancy driven mechanism, throughout the nanomaterial in all spatial dimensions while the ‘Mn defect scaffold’ maintains the structural integrity of the layered structure during charging. Our findings reveal that oxides, which comprise cation disorder, can be potential candidates for electrodes in rechargeable Li-ion batteries.

References

[1] Thackeray, M.M., Johnson, C.S., Vaughey, J.T. Li, N. and Hackney, S.A., J. Mater. Chem. 15, 2257, 2005.

[2] Croy J.R., Gallagher K.G., Balasubramanian M., Long B.R. and Thackeray M.M., J. Electrochem. Soc. 161, A318, 2014.

[3] Thackeray M. M. Progr. Solid State Chem. 25, 1, 1997.

[4] Jain, G.R., Yang, J.S., Balasubramanian, M. and Xu, J.J., Chem. Mater. 17, 3850, 2005.      

[5] P.E.Ngoepe, R.R. Maphanga and D.C. Sayle, (2013), “Towards the Nanoscale”, Chapter 9 in Computational Approaches to Energy Materials, pp 261-290, edited by C.R.A. Catlow, A. Sokol and A. Welsch, John Wiley and Sons Ltd.
Improvement of Interfacial Properties of Sulfide Based All-Solid-State Lithium Secondary Batteries with Li-Si Alloy Anode
Authors: Jin Joo Sung , Park Hye Won , Lim Hyung-Tae
Published: February 2020

Li22Si5 alloy powder was synthesized by mechanical alloying and its electrochemical performance was investigated for use in solid-state battery anodes. Using these anode materials, all-solid-state lithium batteries were assembled with Li4Ti5O12 (LTO) or titanium disulfide (TiS2) as cathode and Li2S-P2S5 as electrolyte. Galvanostatic charge/discharge tests were also performed, and capacity was increased about two times by the additional powder milling process with gradient sturucure, which is consistent with the impedance results. Thus, the results from the present work indicate that using the secondary milling process to refine the electrode powder and gradient structure to reduce interfacial resistance are effective ways to increase the kinetics of alloying and de-alloying with higher utilization of anode active material in all-solid-state lithium secondary batteries.
Degradation of Cobalt Oxide Anode for Lithium Batteries at High Conducting Material Content
Authors: Choi Woo-Sung , Chang Wonyoung , Shin Heon-Cheol
Published: February 2020

Cobalt oxide is considered as promising option for the anode material in next generation rechargeable lithium battery thanks to its large specific capacity (~900 mAh/g). However, its low electrical conductivity causes poor energy efficiency and decreased power density. In order to lower the electrode resistance, many researchers have performed their experiments using the cobalt oxide anode containing large amount of conducting material. On the other hand, the overgrowth of the solid electrolyte interphase (SEI) layer on the cobalt oxide surface and the resulting decrease in specific capacity and energy density are another key issue for its practical use. Specifically, it has been known that the active materials move away from its original position to the overgrown SEI layer during the repetitive charge-discharge cycling and is gradually lost. Accordingly, the larger is the quantity of the SEI layer, the greater is the decrease in the specific capacity.

In this work, we report that the larger amount of conducting material in the cobalt oxide anode leads to its faster degradation during the operation. From the microscopic observation and porosity measurement of the pre- and post-cycled samples with different conducting material contents, it is proved that the free volume in the electrode decreases as the content of conducting material is raised. Furthermore, the analysis of the change in cumulative irreversible capacity loss during charge-discharge cycles shows that the high content of the conducting material promotes the growth of the SEI layer.

In order to further investigate the character of the SEI layers formed at different conducting material contents, the SEI layer formation is mathematically modeled on the basis of the Butler-Volmer relation. By fitting the model to the experimental data, a few physical parameters of the SEI layer can be successfully determined. In particular, from the calculation it is confirmed that the resistivity of SEI layer is considerably changed with the conducting material content. This implies that the incorporation rate of metallic cobalt in the SEI layer during cycling might be critically dependent on the conducting material content.

In this presentation, the optimal content of conducting material is discussed from the viewpoint of cycling stability and rate capability. Furthermore, the validity of the model for the systems used in this work is addressed by an analysis of fitting accuracy.
In Situ High Resolution Synchrotron X-Ray Powder Diffraction Studies of Lithium Batteries
Authors: Amri Mahrez , Fitch Andy , Norby Poul
Published: February 2020

Lithium ion battery technology is the heart in operating modern technology devices such as mobile phones and laptops.  However, as our society is moving towards the utilization of sustainable energy sources, batteries can be foreseen to become an even more important part of the energy infrastructure. They will be used not only for transportation, but also for medium and short term storage as well as for frequency stabilization in intermittent grid scale energy sources such as solar and wind. Thus, the development of new cheaper and safer battery materials with high energy and power density is very important for a successful worldwide energy transition.

The understanding of structural and compositional changes of bulk electrodes in batteries is undoubtedly important. However, it is often transport of electrons and ions across and through interfaces [1] (e.g., between lithiated and delithiated domains) which limits the obtainable power density and battery life time. A challenging and important task is to obtain in situ information about the formation and evolution of interfaces in an operating battery system. This work addresses these challenges and for this purpose we have developed a special microcapillary battery cell allowing diffraction information to be obtained from only the active material during battery operation [2]. High resolution synchrotron x-ray powder diffraction technique has been undertaken to obtain detailed structural and compositional information during lithiation/delithiation of commercial LiFePO4 materials [3].

We report results from the first in situ time resolved high resolution powder diffraction experiments at beamline ID22/31 at the European Synchrotron Radiation Facility, ESRF. We follow the structural changes during charge of commercial LiFePO4 based battery materials using the Rietveld method. Conscientious Rietveld analysis shows slight but continuous deviation of lattice parameters from those of the fully stoichiometric end members LiFePO4 and FePO4 indicating a subsequent variation of stoichiometry during cathode delithiation. The application of an intermittent current pulses during charge using GITT technique shows an oscillation of lattice constants that correlates with the applied current and electrochemical relaxation sequence and may indicate the existence of metastable non-stoichiometric states.

References

[1] R. Malik, F. Zhou, and G. Ceder, Nat. Mater., 10, 587 (2011).

[2] R. E. Johnsen, and P. Norby, J. Appl. Crystallogr., 46, 1537 (2013).

[3] A. K. Padhi, K. S. Nanjundaswamy, and J. B. Goodenough, J. Electrochem. Soc., 144, 1188 (1997).
Dynamic Structures of the Active Sites in Iron-Based Catalysts during ORR
Authors: Jia Qingying , Strickland Kara , Mukerjee Sanjeev , Hafiz Hasnain , Bernardo Barbiellini-Amidei , Tylus Urszula , Ramaswamy Nagappan
Published: February 2020

The prohibitive cost of platinum catalysts for accelerating the sluggish oxygen reduction reaction (ORR) severely hampers the commercialization of fuel cells. Despite recent progress in developing highly active non-precious catalysts (typically Fe−Nx−C) as promising alternatives to Pt, a less empirical synthesis approach is still missing due to the lack of fundamental understanding of the nature of the active sites, as well as their structural effects on ORR activity.

 Herein, the structural and electronic properties of iron meso-tetraphenylporphine chloride (FeTPPCl) pyrolyzed under various temperatures, as well as the state-of-the-art polyaniline (PANI)-derived catalyst [1] are probed using in situ x-ray absorption spectroscopy (XAS) in combination with ab initio calculations. Three Fe2+−N4−like active sites with distinct Fe displacement are identified. All the active sites undergo Fe2+/Fe3+redox transition that triggers the adsorption of hydroxyl intermediate (OH*) from water activation, but they exhibit distinctly different Fe-N switching behavior during ORR, which accounts for their different ORR activities.

Acknowledgements:

The PANI-derived catalysts were prepared and provided by Gang Wu and Piotr Zelenay (Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545). Use of the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), was supported by the U.S. Department of Energy, Office of Basic Energy Sciences. This publication was made possible by the Center for Synchrotron Biosciences grant, P30-EB-009998, from the National Institute of Biomedical Imaging and Bioengineering (NBIB). Support from beamline personnel Dr. Erik Farquhar and Mark Chance (X3B) are gratefully acknowledged.

References

(1) Wu, G.; More, K. L.; Johnston, C. M.; Zelenay, P. Science
2011, 332, 443-447.
(Invited) Separator Requirements for Nonaqueous Flow Batteries
Authors: Darling Robert M.
Published: February 2020

Energy storage is increasingly viewed as a potentially valuable asset for electricity grids composed of high fractions of intermittent sources, like wind turbines, or unreliable generation and transmission services.  Flow batteries are a candidate technology for large-scale, long duration storage of grid energy.  Both aqueous and nonaqueous technologies are being researched and technical progress is being made on both fronts.  The separator between the positive and negative electrolytes is a key technology that must be addressed in both cases.  Nonaqueous electrolytes are generally less conductive than aqueous electrolytes, and the degree to which this can be tolerated in light of higher expected operating voltages needs to be understood.  We use techno-economic modeling to establish ranges of separator properties that are required to attain economic viability for nonaqueous flow batteries and compare these to the properties required for aqueous cells.