bluuebunny/crossref_metadata_2025 huggingface dataset:
A Binder-Free Carbon-RuO2 Composite Cathode for Rechargeable Li-O2 Batteries
Authors: Shin Hyun-Seop , Jung Kyu-Nam , Park Min-Sik , Hwang Jin-Ha , Lee Jong-Won
Published: February 2020

A rechargeable lithium–oxygen (Li–O2) battery is considered as a promising technology for electrochemical energy storage systems, because its theoretical energy density is about ten times higher than those of state-of-the-art Li-ion batteries. The cathode (positive electrode) for Li–O2 batteries is made of carbon and polymeric binders; however, these constituents undergo parasitic decomposition reactions during battery operation, which in turn causes considerable performance degradation. Therefore, the rational design of the cathode is necessary for building robust and high-performance Li–O2 batteries. Here, a binder-free carbon nanotube (CNT) electrode surface-modified by atomic layer deposition (ALD) of dual acting RuO2 as an inhibitor–promoter is proposed for rechargeable Li–O2 batteries. The electrode architecture was designed and fabricated by taking the following features of CNT and ALD into consideration. (i) A free-standing sheet of CNTs can be prepared via a simple filtration procedure without using any binders. (ii) Given that the surface of multi-walled CNTs is very inert, the ALD process yields preferential nucleation–growth of isolated nanoparticles on defect sites rather than producing continuous films on the entire CNT surface. With its proven activity, therefore, RuO2 anchored preferentially to defect sites can play a dual role as an inhibitor (passivating structural defects on CNTs) and a promoter (facilitating electrochemical Li2O2 decomposition). (iii) The ALD process based on sequential, self-limiting reactions allows for the deposition of highly uniform RuO2 nanoparticles within the three-dimensional CNT electrode, which leads to decreased Ru loading while maintaining high catalytic performance. The binder-free RuO2/CNT cathode shows outstanding electrochemical performance as characterized by small voltage gaps (~0.9 V) as well as excellent cyclability without any signs of capacity decay over 80 cycles. The excellent electrochemical performance could be explained by the unique features of the electrode: (i) the absence of polymeric binders with high reactivity with Li2O2 and (ii) the dual function of RuO2 nanoparticles to inhibit carbon decomposition on CNT defects and to promote electrochemical Li2O2 decomposition.
Zn/MnO2 Battery Chemistry with H+ and Zn2+ Co-Insertion
Authors: Sun Wei , Wang Fei , Wang Chunsheng
Published: February 2020

Rechargeable aqueous Zn/MnO2 battery chemistry in a neutral or mildly acidic electrolyte has attracted extensive attention recently because all the components (anode, cathode, and electrolyte) in a Zn/MnO2 battery are safe, abundant, and sustainable. However, the reaction mechanism of the MnO2 cathode remains a topic of discussion. Herein, we design a highly reversible aqueous Zn/MnO2 battery where the binder-free MnO2 cathode was fabricated by in-situ electrodeposition of MnO2 on carbon fiber paper in mild acidic ZnSO4+MnSO4 electrolyte. Electrochemical and structural analysis identify that the MnO2 cathode experience a consequent H+ and Zn2+ insertion/extraction process with high reversibility and cycling stability. To our best knowledge, it is the first report on rechargeable aqueous batteries with a consequent ion-insertion reaction mechanism.

In this study, we demonstrated that the electrodeposited MnO2 experienced the successive H+ and Zn2+ insertion processes with a distinct difference in reaction kinetics during the discharging. The electrodeposited MnO2 has a nanocrystalline structure, in which the particle size is typically less than 10 nm, providing abundant electrode/electrolyte contact interfaces and reduced ion diffusion path and ensuring that the reaction with slow electrochemical kinetics could also happen. The as-designed Zn/MnO2 battery delivered an excellent cycling performance with a low capacity decay rate of 0.007% per cycle for 10,000 cycles at a high rate of 6.5 C.

Figure 1
Pure Hydrocarbon Cathodes for Dual-Ion Batteries – a Trend
Authors: Rodríguez Pérez Ismael Antonio , Ji Xiulei , Carter Rich G. , Lerner Michael M. , Bommier Clement
Published: February 2020

The exploration of electrode materials in the paradigm of battery research has been shifting towards finding materials that are completely renewable, do not contain any transition metals, and are readily available. Recently, we have explored using pure polycyclic aromatic hydrocarbons (PAHs) as electrode materials for dual-ion batteries, where for the first time we demonstrated a crystalline coronene electrode showing flat plateaus at around 4.1 V in charge and discharge in a standard alkyl carbonate electrolyte. A voltage of 4.1 V avoids the use of expensive ionic liquids that are used with the conventional graphite anion insertion electrodes, which insert anions at much higher voltages of above 5.0 V. This electrode delivers a reversible discharge capacity of ~ 40 mA h g-1. We have further demonstrated that perylene and triphenylene, both PAH crystalline solids, exhibit even higher capacities than coronene, ~80 and ~100 mA h g-1, respectively. We are striving to investigate and identify a trend to elucidate structure-property relationships of PAHs that we believe can create a paradigm shift in dual-ion batteries based on pure hydrocarbons as the electrode materials.
Highly Stable Triclinic Polymorph in Nanoscale Na2-2xCo1+XP2O7/C for High-Voltage Na-Ion Battery Cathode
Authors: Song Hee Jo , Kim Jae-Chan , Kim Dong-Wan
Published: February 2020

In Na-ion batteries (NIBs), the net energy density decreases because of the intrinsically low practical capacity and limited Na ion migration compared to that of Li-ion batteries (LIB). So, it is essential to use a high-voltage cathode to compensate these problems [1]. Pyrophosphates are one of the candidates that can be used as high-voltage cathodes [2]. In pyrophosphate-based materials, it is well-known that the operating voltage can be increased if the transition metals (TMs) such as Mn, Co, or Ni are used instead of Fe under electrochemical TM2+
/TM3+ redox reactions [3,4]. Particularly, Na2CoP2O7 with triclinic polymorph exhibits an average operating voltage of ~4.3 V (vs. Na/Na+), which is one of the NIB cathode materials that electrochemically react with Na ions at high-voltage ranges [5]. Unfortunately, however, it is hard to synthesize a pure triclinic polymorph because of its metastability in synthesizing process. So, preparing a highly stable and pure triclinic-polymorph Na2CoP2O7 is challenging work for high-voltage cathode in NIBs.

In this work, we analyze an appropriate elemental ratio of Na/Co in Na2-2xCo1+xP2O7 to prepare a stable triclinic polymorph, and determine suitable synthetic conditions in each bulk and nano compound. The formation of rose or blue phase Na2CoP2O7 with regard to their particle size is schematically illustrated in Fig. 1. Also, the electrochemical performance is measured for the high-voltage NIB cathode. Na1.8Co1.1P2O7 nanoparticles with C (Na1.8Co1.1P2O7-NPs/C) exhibited the discharge capacity of 90 mA h g-1 at the 30th cycle. High operating voltage and good specific capacity could lead to the significant increase in energy density to ~400 Wh kg-1, which is the highest value among polyanionic NIB cathode materials.

Fig. 1. Schematic illustration for the formation of rose or blue phase Na2CoP2O7 with regard to their particle size.

References

[1] V. Palomares, P. Serras, I. Villaluenga, K. B. Hueso, J. Carretero-González, T. Rojo, Energy Environ. Sci. 5 (2012) 5884-5901.

[2] P. Barpanda, S.-i. Nishimura, A. Yamada, Adv. Energy Mater. 2 (2012) 841-859.

[3] G. Hautier, A. Jain, S. P. Ong, B. Kang, C. Moore, R. Doe, G. Ceder, Chem. Mater. 23 (2011) 3495-3508.

[4] M. Tamaru, S. C. Chung, D. Shimizu, S.-i. Nishimura, A. Yamada, Chem. Mater. 25 (2013) 2538-2543.

[5] H. Kim, C. S. Park, J. W. Choi, Y. Jung, Angew. Chem. Int. Ed. 55 (2016) 6662-6666.

Figure 1
Hierarchical Porous Carbon Spheres As an Effective Air Electrode for Li-O2 Batteries
Authors: Jeong Min-Gi , Jung Hun-Gi
Published: February 2020

For years, lithium oxygen (Li-O2) battery has been attracted attention thanks to extremely high energy density which might substitute natural resource [1-3]. However, several issues have obstructed the practical application of Li–O2 batteries such as poor rate capability, low energy efficiency and short cycle life [4-6]. To overcome those drawbacks, herein we propose a novel approach for preparing multi porous hierarchal (micro-, meso-, and macro-) carbon as an efficient positive electrode for Li-O2 batteries. Unlike currently existing carbon material, the hierarchical porous carbon spheres have the integrity to accelerate O2 gas flowing and electrolyte circulation (Li+ and O2-), and to provide enough space for Li2O2 accumulation and O2/Li2O2 transformation. As-synthesized cathode delivered higher discharge capacity (3891 mAh g-1
c) than that of Super P cathode (2427 mAh g-1
c) in deep charge/discharge condition and guided to a high round trip efficiency (~70%) compared to that of carbon black (Super P) (~63%), and efficiently boosted the overall electrochemical performance of the Li–O2 batteries.

Furthermore, ruthenium (Ru) nanoparticles were uniformly dispersed inside the hierarchical architecture to increase the cathode surface adsorption energy toward O2 and decrease the over potential further, thus get benefit from the greater energy efficiency. Ru inclusion in our multi porous hierarchal carbon electrode (Triple hierarchical porous carbon spheres, THPC) effectively modified the morphology of discharge product (Li2O2) to a uniform toroidal-shaped, which is renowned for advancing the OER performance. Certainly, appreciation goes to the unique multi-porous structure of THPC cathode which offered a large number of active sites and allowed a uniform distribution Ru catalyst, thus facilitated a high capacity with prolonged cycle life alongside high energy efficiency.

References

[1] K. M. Abraham, Z. Jiang, J. Electrochem. Soc. 1996, 143, 1.

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

[3] Z. Peng, S. A. Freunberger, Y. Chen, P. G. Bruce, Science 2012, 337, 563.

[4] B. McCloskey, D. Bethune, R. Shelby, T. Mori, R. Scheffler, A. Speidel, M. Sherwood, A. Luntz, J. Phys. Chem. Lett. 2012, 3, 3043.

[5] B. McCloskey, A. Speidel, R. Scheffler, D. Miller, V. Viswanathan, J. Hummelshøj, J. Nørskov, A. Luntz, J. Phys. Chem. Lett. 2012, 3, 997.

[6] J.-L. Shui, N. K. Karan, M. Balasubramanian, S.-Y. Li, D.-J. Liu, J. Am. Chem. Soc. 2012, 134, 16654.
Comparative Study Nickel Rich Layered Oxides: NMC 622, NMC 811 and NCA Cathode Materials for Lithium Ion Battery
Authors: Omenya Fredrick , Chernova Natasha A. , Zhou Hui , Siu Carrie , Whittingham M. Stanley
Published: February 2020

LiCoO2 has conquered the cathode market for lithium ion batteries; recently the mixed transition metal oxide lithium nickel manganese cobalt dioxide have gained attention due to their superior electrochemical properties, better thermal stability, and lower cost. Nickel-rich compositions of lithium nickel manganese cobalt oxide (NMC) have been developed as promising high-energy, high-voltage and improved rate cathode materials capable of significantly increasing the energy density of lithium-ion batteries.

Here we report a systematic comparative study on rate capability, charge discharge behavior and nickel/lithium mixing of the nickel-rich layered oxides, NMC622, NMC811 and NCA. The results showed that both NMC622 and NMC811 have pure hexagonal layered phase with Ni/Li mixing below 4%. Both samples have similar specific capacity of about 220 mAh/g at current densities, C/10; however, NMC811 demonstrated superior electrochemical performance compared to NMC611 at higher rates. The 622 sample showed a strong dependence on the electrode loading, higher electrode loading above 15 mg/cm2 had poor performance compared to lower loading at the same current density in mA/cm2 while NMC811 sample does not show such loading dependence. This work was supported by the DOE-EERE-Battery500 consortium.
Reduce Graphene Oxide Micro-Ball Containing High Sulfur Nanoparticle Content for High Performance Lithium-Sulfur Batteries
Authors: Yeon JeongSeok , Yun Sol , Park Ho Seok
Published: February 2020

Lithium-sulfur batteries are receiving enormous interest because of its high theoretical capacity. (1,675mAhg-1) However, their commercialization still hindered by several issues, including short cycle life, low cycling and high self-discharge rate. Moreover, due to the low electrical conductivity and polysulfide dissolution (Li2S2 and Li2S), sulfur-based electrodes are limited its specific discharge capacity. Herein, we report a facile synthesis method for preparing reduced graphene oxide composites containing high sulfur content (up to 80%). With this strategy, we are used to homogeneously mixed the aqueous dispersed sulfur and the GO solution. And then electrode synthesis by using Spray method. Consequently, the electrode shows an initial capacity of 1211mAhg-1 and can retain a reversible capacity of 946mAhg-1 after 100 charge/discharge cycles at 0.1C and the strong covalent bonds between sulfur and rGO that enable to improve efficiency during charge/discharge.
Wettability between Controlled MWCNT-S Cathode and Electrolyte for High Performances of Lithium-Sulfur Batteries
Authors: Shin Subeom , Hwang Jang-Yeon , Kim Hee Min , Sun Yang-Kook
Published: February 2020

The lithium-sulfur (Li-S) battery has emerged as a next-generation rechargeable battery, owing to the involvement of multiple electrons during the redox reactions between Li and S, which provides high theoretical energy density (2,600 Wh kg-1) and specific capacity (1,675 mAh g-1). In addition, due to abundance of elemental sulfur and its environmental compatibility, Li-S battery has been considered the much more attractive power sources.1,2 The present study demonstrates how to improve the electrochemical performance and energy density of lithium-sulfur batteries based on controlling the wettability between the freestanding electrode and the electrolyte. First, to improve the volumetric energy density, we reduced the thickness of freestanding electrode by the applying pressure. Second, in order to improve electrolyte conductivity and wettability for pressed freestanding electrode, we reduced the viscosity of electrolyte solution by reducing the LiTFSI salt concentration.3,4 Through these controls, the Li-S cell is constructed from a pressed freestanding carbon nanotube-sulfur cathode, 0.5 M LiTFSI in DME/DOL with 0.4 M LiNO3 as a low-viscosity electrolyte (0.72 cP), and Li-metal foil as an anode. As a result, we can obtain a high discharge capacity of 1,400 mAh g-1 at 0.1 C and excellent cycle retention of 95% after 80 cycles at 0.5 C in coin-type cell. In addition, scale-up (3 by 5 cm) pouch-type Li-S cell delivers a high discharge capacity of 500 mAh at 0.1 C with high gravimetric and volumetric energy densities.5

References

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

J.-Y. Hwang, H. M. Kim, S. K. Lee, J. H. Lee, A. Abouimrane, M. A. Khaleel, I. Belharouak, A. Manthiram, Y.-K. Sun, Adv. Energy Mater. 2016, 6, 1501480

J.J. Hu, G. K. Long, S. Liu, G. R. Li, X. P. Gao, Chem. Commun.,
2014,
50, 14647

H.-S. Kang, Y.-K. Sun, Adv. Funct. Mater., 2016, 26, 1225

H.-S. Kang, E. Park, J.-Y. Hwang, H. Kim, D. Aurbach, A. Rosenman, Y.-K. Sun, Adv. Mater. Technol. 2016, 1600052
The Use of Mixed Organic/Ionic Liquid Electrolytes with Forcespun Metal Oxides/Carbon Microfiber Electrodes in Lithium Ion Batteries
Authors: Villarreal Jahaziel , Zuniga Luis , Valdez Alejandra , Alcoutlabi Mataz
Published: February 2020

We present results on the Forcespinning (FS) of PAN solution precursors for the mass production of metal/oxides carbon (MO/C) composite microfibers as anode materials for Lithium-ion batteries. The MO/C composite microfiber anodes are produced using a scalable technique (FS) and subsequent thermal treatment (calcination). The composite anodes were porous and flexible. The flexible composite microfibers were directly used as binder free electrodes in lithium-ion batteries. Mixed organic/ionic liquid electrolytes (MOILEs) were employed in Lithium ion cell cycling studies with the MO/C composite fibers and composite fiber cathodes to investigate the electrochemical and cycling performance of the Li-ion cells. The ionic conductivity of MOILEs and the electrochemical performance of LIB cells were investigated at different temperatures and current rates. 1-Ethyl-3-Methyl-imidazolium Lithium bis(trifluoromethanesulfonyl) imide (EMI-TFSI) ionic liquid was synthesized in our laboratory by reacting the EMI cation and TFSI ion in a 1:1 mole ratio. The EMI-TFSI ionic liquid and LiTFSI salt were mixed with organic liquids (Ethylene carbonate (EC) dimethyl carbonate (DMC) and Succinonitril (SN) to improve the ionic transport of the electrolyte during the charge/discharge cycles. The MO/C composite electrodes delivered a good electrochemical performance and Columbic efficiency when used as half and full cells. The electrochemical performance of the Forcespun composite fiber cathodes was also investigated in half-cell cycling.
Material-Dependent Solid Electrolyte Interphase Formation Behavior of Artificial Graphite Battery Anodes
Authors: Pham Hieu Quang , Kim Byoung Ju , Jo Hyuntak , Kang Sung , You Seung-Jae , Song Seung-Wan
Published: February 2020

For the past decades, natural graphite has been widely used as anode material in commercial Li-ion batteries. Although natural graphite holds the strong merits such as low cost and stable performance, there are several issues to consider natural graphite; safety issue due to Li dendrite formation at low charge potential close to that of Li metal, its low gravimetric capacity and volumetric capacity than theoretical values of 372 mAhg−1 and 850 mAhcm−3, respectively, and a large initial irreversible capacity loss due to solid electrolyte interphase (SEI) formation.2 Those deleteriously affect the safety and performance of Li-ion batteries. Artificial graphite, which is a material made from petroleum or coal tar, provides higher safety, reliability and performance than natural graphite.3 However, the effects of the type of artificial graphite on the SEI formation and their correlation to cycling performance are little reported. Here, we present the systematic investigation of the SEI formation behavior depending on the characteristics of model artificial graphite (AG) anode active materials,4 which include different particle characteristics including particle size, surface area and graphitization degree, etc., in the conventional electrolyte with 1 wt% vinylene carbonate (VC) additive as a SEI forming agent, and the correlation among particle characteristics, the SEI formation and stability, interfacial resistances and cycling performance of Li//AG half-cells and full-cells of AG//LiCoO2.

Acknowledgements

This work was supported by Research Institute of Industrial Science & Technology (RIST).

References

B. Scrosati, Chem. Rec., 5, 286 (2005).

H. Zheng, K. Jiang, T. Abe, and Z. Ogumi, Carbon, 44, 203 (2006).

Y.-S. Park, T.-W. Lee, M.-S. Shin, S.-H. Lim, and S.-M. Lee, J. Electrochem. Soc., 163, A3078 (2016).

H. Q. Pham, B.-J. Kim, H. Jo, S. Kang, S.-J. Yoo, S.-W. Song, J. Electrochem. Soc., 164, A3045 (2017).
New Additives for Li Ion Batteries
Authors: Liao Chen , Shkrob Ilya A , Sahore Ritu , Tornheim Adam , Abraham Daniel P , Zhang Zhengcheng
Published: February 2020

None of the battery chemistry would be possible without the component of electrolyte and additive, which is responsible for the formation of Solid Electrolyte Interface (SEI), the interface between the electrodes and the electrolyte. Studies have showed that EC would be reduced at ~ 0.7 V vs Li/Li+, and the reduction of EC forms SEI consisting of organic polymer, inorganic salts that serves as a filter for lithium ion conducting. The typical electrolyte consists of 1.0 to 1. 2 M of a lithium salt (such as LiPF6 or lithium bis(trifluoromethylsulfonyl)imide, LiTFSI) in mixed solvents of carbonates type. For example, the current prevalent electrolyte Gen 2 consists of 1.2 M LiPF6 in 30 wt % of ethylene carbonate (EC) and 70 wt % of ethyl methyl carbonate (EMC). Another vital role of the additive is to mitigate unavoidable electrolyte decomposition occurred both at anode and cathodes side during the charge/discharge process. Apparently, the quality of the SEI significantly affects the battery performance.

We are reporting a series of new additives for lithium ion batteries, and the ability of the additives to mitigate the presence of HF in the electrolyte was probed by solution-state nuclear magnetic resonance (NMR) spectroscopy. A galvanostatic charge/discharge protocol cycled between 3.0-4.4V at 30°C with periodic hybrid pulse power characterization (HPPC) tests gave electrochemical information from which capacity and impedance data were derived. Investigation of the harvested electrodes using X-ray photoelectron spectroscopy (XPS) after being cycled shed light on surface films formed and transition metal dissolution.
Oxidatively Stable Fluorinated Sulfones Electrolytes for High Voltage High Energy Li-Ion Batteries
Authors: Su Chi-Cheung , He Meinan , Tornheim Adam , Cao Jiyu , Redfern Paul , Curtiss Larry A , Shkrob Ilya A , Zhang Zhengcheng
Published: February 2020

Developing a high-voltage enabling electrolyte is extremely critical for the success of the next generation high-energy density lithium-ion battery especially for electric vehicles. Material scientists have developed new cathode materials with improved specific capacity[1,2] and operating voltage (5 V vs. Li+/Li).[3,4] However, designed for a 4V-class lithium-ion chemistry, the conventional electrolyte suffers from oxidation instability on the charge cathode/electrolyte interface at high charging voltages which leads to severe transition metal (TM) dissolution and rapid capacity fading. The voltage instability of electrolyte becomes the bottleneck for the extensive application of the high voltage cathode materials. Thus, new electrolytes with elevated voltage stability has been widely explored.[5-8]

Here we report a new class of fluorinated electrolytes comprising novel fluorinated sulfones including ((trifluoromethyl)sulfonyl)ethane (FMES), 1-((trifluoromethyl)sulfonyl)propane (FMPS) and 2-((trifluoromethyl)sulfonyl)propane (FMIS).[9] These compounds have been synthesized via new synthetic routes and evaluated as electrolyte materials under high voltage operation. The results indicate that sulfones with an α-trifluoromethyl group possess enhanced oxidative potential and reduced viscosity as compared to their non-fluorinated counterparts. The α-fluorinated sulfones also show enhanced wetting ability with polyolefin separator. A facile synthesis method for a reported sulfone 1,1,1-trifluoro-3-(methylsulfonyl)propane (FPMS) was also developed. With the new reaction method, large quantity of material was obtained and comprehensive electrochemical properties of FPMS as high voltage electrolyte was evaluated. Unlike the α-fluorinated sulfones, the γ-fluorinated sulfones resemble the property of the non-fluorinated ones.

References:

[1] Nyten, A.; Abouimrance, A.; Armand, M.; Gustafsson, T.; Thomas, J. O. Electrochem. Commun., 2005, 7, 156-160.

[2] Ellis, B. L.; Makahnoul, R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F., Nat. Mater., 2007, 6, 749-753.

[3] Hu, M.; Pang, X.; Zhou, Z. J., Power Sources, 2013, 237, 229-242.

[4] Santhanam, R.; Rambabu, B. J., Power Sources, 2010, 195, 5442-5451.

[5] He, M.; Su, C. C.; Feng, Z.; Zeng, L.; Wu, T.; Bedzyk, M. J.; Fenter, P.; Wang, Y.; Zhang, Z., Adv. Energy Mater.,
2017, 7, 1700109.

[6] He, M.; Su, C. C.; Peebles, C.; Feng, F.; Connell, J. G.; Liao, C.; Wang, Y.; Shkrob, I. A.; Zhang, Z., ACS Appl. Mater. Interface, 2016,
8(18), 11450-11458.

[7] Kunduraciz, M.; Amatucci, G.G., J. Electrochem. Soc.,
2006, 153, A1345-A1352.

[8] Wolfenstine, J.; Aleen, J., J. Power Sources, 2005, 142, 389-390.

[9] Su, C. C.; He, M.; Redfern, P. C.; Curtiss, L. A.; Shkrob, I. A.; Zhang, Z., Energy Environ. Sci.,
2017, 10, 900-904.

Figure 1
(Invited) High Voltage Aqueous Batteries
Authors: Xu Kang
Published: February 2020

High voltage energy storage devices have always been supported by non-aqueous electrolytes, whose intrinsic wide stability window as well as the capability to form protective interphases at extreme potentials ensures the reversibility of electrochemical reactions, but whose high flammability, toxicity and sensitivity to ambient also bring compromises of safety, environment and rigid-format.

Replacing non-aqueous solvents with water could provide an ideal resolution of these issues on materials level, if the water molecules could be electrochemically stabilized at potentials where ordinary aqueous electrolytes decompose. This talk will summarize the efforts in this direction, and the various high voltage aqueous battery chemistries thus enabled.
Design and Preparation of Cathode Catalysts for High-Performance Lithium-Oxygen Batteries
Authors: Wang Kai-Xue
Published: February 2020

The lithium-oxygen batteries have received considerable attention recently due to their high theoretical energy densities, which is highly desirable for long-range electric vehicles. However, their poor electrochemical performance, particularly the large overpotential, makes the practical application of Li-O2 battery full of challenge. In a typical prototype, non-aqueous Li-O2 battery is composed of a catalytic cathode, a lithium anode, and an organic Li+ conducting electrolyte. During the discharge process, oxygen molecules are reduced and reacted with the Li+ ions from the electrolyte (oxygen reduction reactions, ORRs), leading to the formation of dissoluble Li2O2 attached to the porous cathode. These Li2O2 species would reversibly decompose into Li+ ions and oxygen (oxygen evolution reactions, OERs) in the following charging process. Thus, the design of cathode catalysts with high ORR and OER reactivity, and porous structures with appropriate pore size for the permeation of O2 is of particular importance. In addition, polymer binders would react with superoxide Li2O2, consequently leading to the instability of Li-O2 batteries. It is also highly desired to develop novel binder-free cathode materials. Herein, strategies have been proposed for the preparation of free-standing porous structures promote the ORR and OER activities for high-performance Li-O2 batteries.
Improving Cathode and Electrolyte Stability in Lithium-Oxygen Batteries
Authors: Dornbusch Donald A. , Dynys Frederick W. , Radhakrishnan Balachandran , Viggiano Rocco , Lawson John W
Published: February 2020

Lithium-Oxygen and Lithium-Air batteries have been of great interest for energy storage due to their high theoretical energy density, which have the potential to enable other technologies such as electric and hybrid aircraft. However, due to the reactivity of the discharge product in nonaqueous electrolytes cells, cycling performance is severely inhibited which occurs due to side reactions at both sides of the deposited lithium peroxide (Li2O2), and consumes both the carbon from the supporting cathode structure as well as the organic solvent from the electrolyte. In this study, a synergistic approach utilizing computational modeling and experimental screening was applied to investigate novel cathode alternatives and coatings in addition to alternative electrolyte solvents to increase material stability and avoid both forms of side reaction driven decomposition.
Insights into the Kinetics of Redox Mediation for Li-O2 Batteries: A Dems and RRDE Study
Authors: Bawol Pawel P. , Thimm Jan H. , Baltruschat Helmut
Published: February 2020

Due to its theoretical high specific energy Li-O2 systems have generated much interest within the electrochemical community [1]. Understanding the fundamentals of this system is import to improve it. Therefore, much effort has been put into characterizing the products and the mechanism of the underlying electrolyte systems and electrodes (also by ourselves [2-5]). Recently in the electrolyte, soluble redox mediators were proposed as additives to improve the sluggish kinetics of the oxygen reduction reaction (ORR) as well as the oxygen evolution reaction (OER)[6, 7]. Although the impact of this redox mediators is impressive, very little is known about the underlying mechanism.

Therefore, we focused in this study our research in the mechanism of redox mediation of the ORR. We applied rotating ring disc technique (RRDE) as well as the differential electrochemical mass spectrometry (DEMS) to get insights into the kinetics of the mediated ORR and into the amount of consumed electrons per oxygen. The DEMS experiments were performed in a thin layer geometry without convective transport within the cell. In addition, the DEMS setup is highly sensitive to the gases formed during ORR and OER. At higher electrode potentials, the amount of evolved CO2 is reduced by adding a redox mediator to the electrolyte. We also observed that the amount of consumed oxygen is increased compared to the supporting electrolyte without redox mediator. In order to investigate the impact of the cationic charge density on the mechanism of the mediated ORR we also performed measurements in K+-, Mg2+-, Ca2+- containing electrolytes solutions. In our analysis of the data, we could calculate the share of current going into the mediation of the ORR. This analysis showed that for the investigated cations the amount of consumed electrons per oxygen molecule is 2 e-/O2. We found out, that the reaction speed of ORR could be influenced by changing the cation of the supporting electrolyte. The RRDE study revealed the generation of Li2O2 within the electrolyte volume through an analysis of the rotational dependency within the experiments.

[1] K. M. Abraham and Z. Jiang, J. Electrochem. Soc., 143, 1 (1996).

[2] P. Reinsberg, A. Weiss, P. P. Bawol and H. Baltruschat, J. Phys. Chem. C, 121, 7677 (2017).

[3] C. J. Bondue, P. P. Bawol, A. A. Abd-El-Latif, P. Reinsberg and H. Baltruschat, J. Phys. Chem. C, 121, 8864 (2017).

[4] C. Bondue, P. Reinsberg, A. A. Abd-El-Latif and H. Baltruschat, Phys. Chem. Chem. Phys., 17, 25593 (2015).

[5] H. M. A. Amin, C. Molls, P. P. Bawol and H. Baltruschat, Electrochim. Acta (2017).

[6] B. D. McCloskey and D. Addison, ACS Catalysis (2017).

[7] X. Gao, Y. Chen, L. Johnson and P. G. Bruce, Nat. Mater., 15, 882 (2016).
Analyzing Microstructural and Electrolyte Phase Limitations in Li-Air Battery Performance
Authors: Mistry Aashutosh N , Mukherjee Partha P.
Published: February 2020

Lithium-air batteries, despite having a superior theoretical performance as compared to other lithium chemistries, demonstrates poor discharge performance. The discharge product in organic electrolyte Li-air cells is lithium peroxide (Li2O2), which precipitates as a solid phase during discharge and gives rise to pore network evolution for the porous electrode. To make matters worse, lithium peroxide is electronically insulating and in turn evolves the electrochemically active interface. On the other hand, as dissolved oxygen is consumed during electrochemical discharge, additional oxygen from air is to be transported from ambient to reaction zone. Finite solubility and finite rate oxygen transport may lead to oxygen starvation for faster operation (related with electrolyte phase transport description). The relative severity of these microstructural and electrolyte phase limitations jointly determines the cell performance. Consistent and comprehensive descriptions for microstructural evolution and electrolyte phase transport are developed here, and in turn physicochemical evolution in Li-air cells investigated. Depending on the severity of these resistive modes, different strategies for cell performance improvement are highlighted.
Micro-Patterning Technology and Conformal Protective Coating for Lithium Metal Electrodes
Authors: Park Joonam , Jin Dahee , Byun Seoungwoo , Roh Youngjoon , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Li metal is still one of promising anode candidates for advanced lithium secondary batteries due to its lowest potential (-3.045V vs. SHE) and high specific capacity (3860 mAh g-1). However, dendrite formation during Li deposition process is known to be the main knotty problem to be solved. To overcome this challenging issue, a variety of previous approaches such as protection layer on Li metal, electrolyte additives, all-solid-state electrolytes, etc. have been attempted consistently (see Figure). However, their improvement levels are limited and insufficient to apply them to commercial-level secondary batteries.

To control lithium deposition/stripping location in the lithium metal, we have already proposed a micro-patterning technology with micro-needle and micro-stamp. [1-2] When micro patterns are formed on the lithium metal, the lithium deposition/stripping reaction is preferentially taken place within the patterns. With a simulation tool, Comsol Multiphysics ®, we can provide some discussion on which dimension will lead to better electrochemical performance. In addition, we will share state-of-the-art experimental results based on thin lithium metals and electrolyte additives, together.

References

1) M.-H. Ryou†, Y.M. Lee†, Y. Lee, M. Winter, and P. Bieker, Advanced Functional Materials 25(6) (2015) 834

2) J. Park†, J. Jeong†, Y. Lee†, M. Oh, M.-H. Ryou, and Y.M. Lee, Advanced Materials Interfaces 3 (2016) 1600140

Figure 1
Oxygen Reduction Reaction on Nitrogen and Cobalt Modified Silicon Carbide Derived Carbon in Acidic Media
Authors: Teppor Patrick , Jäger Rutha , Härk Eneli , Joost Urmas , Tallo Indrek , Paiste Päärn , Kirsimäe Kalle , Lust Enn
Published: February 2020

Active research is currently being done to study and develop alternative cathode catalyst materials for the purpose of lowering the oxygen reduction reaction (ORR) overpotential in polymer electrolyte membrane fuel cells. In this regard, carbon materials modified with nitrogen and a non-platinum group metal, either iron or cobalt, have shown promising results.[1-3]

In this work, non-platinum group metal and nitrogen type ORR catalysts were successfully synthesized via a simple solution-based method using a silicon carbide derived carbon support, cobalt and different nitrogen precursors, namely 2,2’-bipyridine and 1,10-phenanthroline.[2]

The characteristics of the resulting materials were studied using various physical and electrochemical methods. The main physical characterization was done by low-temperature nitrogen sorption analysis, X-ray photoelectron spectroscopy and inductively coupled plasma mass spectrometry. The electrochemical characterization was done in an acidic environment using the rotating disc electrode and cyclic voltammetry methods carried out in a three-electrode electrochemical cell.

According to the electrochemical measurements, modifying the carbon support with cobalt and nitrogen increased the half-wave potential value of the ORR curves by around 460 mV. Furthermore, the achieved ORR activities of both synthesized catalyst materials were comparable to the activities of similar catalysts presented in the literature. The ORR stabilities of both materials were additionally studied and the calculated activity decrease speeds were found to be somewhat smaller than those reported for similar materials.[3]

[1] H. T. Chung, D. A. Cullen, D. Higgins, B. T. Sneed, E. F. Holby, K. L. More, P. Zelenay. Science 357 (2017) 479.

[2] F. Roncaroli, E. S. D. Molin, F. A. Viva, M. M. Bruno, E. B. Halac. Electrochimica Acta, 174 (2015) 66.

[3] S. Li, L. Zhang, H. Liu, M. Pan, L. Zan, J. Zhang. Electrochimica Acta 55 (2010) 4403.
In-Situ Electrochemical X-Ray Diffraction of Pt Oxidation and Reduction in Hydrogen Fuel Cells
Authors: Martens Isaac , Drnec Jakub , Blanco Maria Valeria , Pusa Janne , Honkimäki Veijo , Wilkinson David P. , Bizzotto Dan
Published: February 2020

The commercialization of proton exchange membrane (PEM) fuel cells has increasingly demanded lower precious metal catalyst loadings. A better understanding of platinum nanoparticle degradation mechanisms and electrochemistry will be essential in preserving fuel cell performance over increased device lifetimes. In-situ synchrotron x-ray diffraction/scattering is a powerful tool for characterizing commercial catalyst layers in an electrochemical cell1-2. Recent advances in hardware presently allow time-resolved scattering measurements and diffractive imaging3 without compromising electrochemical experiments. New cell designs4 greatly improve the ease and flexibility of measuring membrane electrode assemblies under environmental conditions and Pt loadings relevant for fuel cell operation and degradation.

The structural effects and kinetics of platinum electrochemistry on nanoparticles can be directly probed using x-ray diffraction. The evolution of nanoparticle strain, atomic ordering, oxidation, and dissolution are monitored in the presence of adsorbing molecular species under potential control. We show how by monitoring Pt particle size, and Pt lattice strain, it is possible to deconvolute chemical and electrochemical steps in the mechanism of Pt oxidation and reduction. Measurements using conventional single crystal and half cell experiments are compared with x-ray diffraction on an operating PEM fuel cell cathode. Several differences in surface chemistry between these cell configurations are detected, which is directly relevant to the development of better accelerated aging and stress-testing protocols.

Particular attention has been given towards developing these advanced synchrotron techniques as useful tools for the non-specialist. Recent advances improving the accessibility of in situ diffraction for the electrochemical community are discussed.

Figure 1. X-ray transparent half-cell suitable for high-energy x-ray diffraction of membrane electrode assemblies (left). X-ray powder diffractogram obtained from fuel cell cathode during the oxygen reduction reaction (right).

Imai, K. Izumi, M. Matsumoto, Y. Kubo, K. Kato and Y. Imai. J. Am. Chem. Soc., 2009, 131 (17), pp 6293–6300

K. Sasaki, N. Marinkovic, H.S. Isaacs, and R.R. Adzic. ACS Catal., 2016, 6 (1), pp 69–76

F. Reikowski, T. Wiegmann, J. Stettner, J. Drnec, V. Honkimaki, F. Maroun, P. Allongue, O.M. Magnussen. J. Phys. Chem. Lett., 2017, 8 (5), pp 1067–1071

B. Pinaud, A. Bonakdarpour, L. Daniel, J. Sharman and D.P. Wilkinson. J. Electrochem. Soc. 2017, 164 (4), pp F321-F327

Figure 1
Preparation and Characterization of Monovalent Cation Selective Membranes Prepared by a Layer-By-Layer Pore-Filled Technique
Authors: Choi Young-Woo , Kang Naeun , Jeong Nam-Jo , Kim Chan-Soo
Published: February 2020

Membrane fouling is one of fatal barriers in electrochemical water treating technologies using ion exchange membranes (IEM) such as electrodeionization (EDI), Electrodialysis (ED), capacitive deionization (CDI), and reverse electrodialysis (RED). Calcium and Magnesium ions are representative foulants which make cake-like scale on the IEMs, leading to high resistance and low durability. In order to minimize membrane fouling in systems using IEMs, we are having developed monovalent cation selective membranes prepared by a layer-by-layer pore-filled technique. Anion exchangeable electrolytes are pore-filled on both surfaces of a semi-pore-filled cation exchange membrane (layer-by-layer). A porous PE substrate (<20 um) is used to be filled with electrolytes and crosslinking agents and to be polymerized. Monovalent cation selectivity against divalent ions, calcium and magnesium ions, of the resulting membranes was evaluated using 1N MgCl2, CaCl2 and NaCl solutions.
Annealing Effect of Nafion-Propyl-1,2,3-Triazole Membrane By Autoclave Solution Processing
Authors: KIM Je-Deok , Ghil Lee-Jin , Ohira Akihiro
Published: February 2020

Keywords: Autoclave solution processing, Nafion-propyl-1,2,3-triazole membrane, Annealing treatment, PEMFCs

Proton exchange membrane fuel cells (PEMFCs) are one of the most promising candidates among the various types of fuel cell systems due to their applications and mode of operation. There is a need for improvements to perfluorinated polymers such as lower membrane cost, high conductivity at high temperature (> 90°C) and low humidity, etc.

We prepared various acid-base composite membranes, and base compounds were found to be well incorporated into the nanostructure of sulfonic acid phase in Nafion polymers [1-9]. A propyl-1,2,3-triazole was synthesized by a perfluorosulfonic acid (PFSA) polymer solution (Nafion) with propyl alcohol using room temperature (RT) and autoclave (AC) solution processing [5-8]. Both the blend membranes were flexible. However, the Nafion-propyl-1,2,3-triazole membrane was required more improved chemical and mechanical stability. An annealing treatment was conducted at the temperature of 180 oC for 3 h. The annealing processing is responsible to increase a crystallinity in the nanostructure of pristine membrane. The annealed membrane showed more improved property than pristine in the chemical, mechanical, and crystallinity.

Acknowledgements

This work was partially supported by the MEXT program for development of environmental technology using nanotechnology.

References

[1] J.-D. Kim, Y. Oba, M. Ohnuma, M.-S. Jun, Y. Tanaka, T. Mori, Y.W. Choi, Y.-G. Yoon, J. ECS, 2010; 157: B1872-B1877.

[2] J.-D. Kim, Y. Oba, M. Ohnuma, T. Mori, C. Nishimura, I. Honma, Solid State Ionics, 2010; 181: 1098-1102.

[3] J.-D. Kim, T. Mori, S. Hayashi, I. Honma, J. ECS, 2007; 154: A290-A294.

[4] J.-D. Kim, M. Onhuma, C. Nishimura, T. Mori, A. Kucernak, J. ECS, 2009; 156: B729-B734.

[5] J.-D. Kim, M.-S. Jun, C. Nishimura, Y.-W. Choi, ECS Transactions, 2011; 35: 241-250.

[6] J.-D. Kim, M.-S. Jun, M.L. Divona, Fuel Cells, 2013; 13: 65-71.

[7] J.-D. Kim, M.-S. Jun, H.-W. Rhee, ECS Transactions, 2013; 58: 271-282.

[8] J.-D. Kim, L.-J. Ghil, M.-S. Jun, J.-K. Choi, H.-J. Chang, Y.-C. Kim, H.-W. Rhee, J. ECS, 2014; 161: F724-F728.

[9] J.-D. Kim, M.-S. Jun, Materials Science forum, 2014; 783-786: 1692-1697.
(Invited) Influence of Mechanical Stress on Lithium Chemical Potential in Lithium Ion Battery Electrodes
Authors: Amezawa Koji , Funayama Keita , Kimura Yuta , Mahunnop Fakkao , Nakamura Takashi , Kuwata Naoaki , Kawamura Junichi , Kawada Tatsuya
Published: February 2020

In solid-state ionic devices, such as all-solid-state lithium ion batteries (ASSLIBs) and solid oxide fuel cells (SOFCs), mechanical stress is introduced at the electrode/electrolyte hetrointerfaces due to differences in the crystal structures and the chemical/thermal expansion coefficients. A mechanical strain at the heterointerface might affect thermodynamic and kinetic properties of the electrodes and the electrolyte, resulting in the performance deterioration or improvement of the devices. Although such a so-called “mechano-electro-chemical coupling effect” has been empirically demonstrated by many researches, the origins of the effect are not fully understood so far.

In this presentation, we will discuss the influence of mechanical stress on thermodynamic properties of solid-state ionic materials. As a model case, lithium chemical potential in electrode materials for ASSLIBs under mechanical stress was investigated. A dense thin film electrode of LiCoO2, Li2MnO4 or LiFePO4 was deposited on a plate of solid-state lithium ion conductors, and the variation of the lithium chemical potential in the electrode was evaluated by measuring electromotive force under compressively- and tensely-strained conditions. Electromotive force accompanied by mechanical strain could be clearly observed, demonstrating a “mechano-electro-chemical coupling effect”. The influence of mechanical stress was different depending on the kinds of electrode material. The observed change in the electromotive force could be thermodynamically related to the lithium partial molar volume of the electrodes.
Phase-Field Modeling of Solid Electrolyte Interphase (SEI) Cracking in Lithium Batteries
Authors: Guan Pengjian , Liu Lin
Published: February 2020

Lithium batteries are becoming ubiquitous in portable and transportation energy storage systems. Unfortunately, severe degradation occurs and results in a solid electrolyte interphase (SEI) between the electrode and the electrolyte. On the other hand, the SEI can prevent the exfoliation of electrode materials and inhibit further electrolyte decomposition. It is believed that SEI cracks due to either of its unstable structure or the cracking of electrode during electrochemical cycling. However, our understanding of the fracture in the SEI remains tenuous due to the complexity of experimentation as well as numerically tracking the interface motion explicitly upon cycling. The phase-field method that can handle complex interfacial evolution without tracking the interface motion explicitly upon cycling. In addition, the phase-field method integrates morphological with electrochemical analysis as well as shed light on mechanical reliability. Thus, we adopt phase-field method to investigate the cracking of the SEI in Lithium batteries. Without loss of generality, we propose a nanoparticle agglomerate structure (i.e., primary particles and binder) to represent a secondary particle wildly adopted by different lithium batteries. Two types of SEI are considered herein, the compact layer and the porous layer. The location where has the maximum lithium concentration gradient will be picked up to investigate the crack propagation in the compact layer and the porous layer of SEI. The flux vector of lithium diffusion is assumed to be proportional to the gradient of the chemical potential. The main capacity loss due to the SEI fracture will also be estimated in this work.

Figure 1
Sustainable and Highly Robust Anodic C,C-Cross-Coupling Reaction of Phenols
Authors: Riehl Barbara , Waldvogel Siegfried R.
Published: February 2020

Electroorganic synthesis is a highly attractive technique to synthesize non-symmetric biphenols. These substances offer a unique structural motif in natural products and are important ligands for catalysts.[1] Typically, cross-coupling reactions need expensive transition-metal catalysts for the construction of biphenols.[2] Furthermore, commonly used methods require leaving groups or oxidizers. This leads to significant amounts of reagent waste during these cross-coupling reactions.

We established efficient pathways for the C,H activation cross-coupling to non-symmetric biphenols with tolerance of broad substitution pattern and a broad range of current density[3]. In this method, reagent waste is significally avoided due to electrons being the only reagent. Efficient and straightforward electro-organic reactions are highly attractive and sustainable.[4] Therefore, our developed method is ecological as well as economic and represents an inherently safe, and easily scalable alternative synthetic approach, which is superior to other oxidizers.[5]

References:

[1] (a) G. Bringmann, T. Gulder, T. A. M. Gulder, M. Breuning, Rev.
2011, 111, 563–639; (b) J. M. Brunel, Chem. Rev.
2005, 105, 857–898.

[2] (a) L. Ackermann, Modern Arylation Methods, Wiley-VCH, Weinheim, 2009; b) G. Dyker, Handbook of C-H Transformations, Wiley-VCH, Weinheim, 2005.

[3] Wiebe, B. Riehl, S. Lips, R. Franke, S. R. Waldvogel, Sci. Adv.
2017, 3:eaao3920.

[4] Elsler, D. Schollmeyer, K. M. Dyballa, R. Franke, S. R. Waldvogel, Angew.
Chem.
2014, 126, 5311–5314; Angew. Chem. Int. Ed.
2014, 53, 5210–5213.

[5] Riehl, K. M. Dyballa, R. Franke, S. R. Waldvogel, Synthesis
2017, 49, 252–259.

Figure 1