bluuebunny/crossref_metadata_2025 huggingface dataset:
A Moisture- and Oxygen-Impermeant Separator for Aprotic Lithium-Oxygen Batteries
Authors: Kim Byung Gon , Choi Jang Wook
Published: February 2020

Lithium-oxygen batteries (Li-O2) have lately received considerable attention because of their exceptional potential gravimetric energies, i.e., 3~5 times compared to those of conventional lithium ion batteries. In spite of the unparalleled theoretical gravimetric energy, lithium-oxygen batteries are still under research because of their insufficient cycle lives. This shortcoming is associated with several entangled fading mechanisms [1,2]: partly irreversible nature of the air-cathode, electrolyte evaporation, unstable lithium anode interface, etc. While the reversibility in air-cathodes has been recently improved significantly by the deepened understanding on the electrode-electrolyte reaction and the integration of diverse catalysts, the stability of the lithium anode interface has received relatively much less attention. The destabilization of the lithium anode interface by crossover of water and oxygen from the air-cathode side can indeed cause as fatal degradation for the cycle life as the irreversibility of the air-cathodes [3]. Here we report that cheap poreless polyurethane separator can effectively prevent this crossover while allowing the selective diffusion of lithium ions by high electrolyte uptake of the polyurethane separator through the interchain space. The polyurethane separator also protects lithium anodes from redox mediators, lithium iodide, used to enhance the reversibility of the air-cathode reaction. Based on the lithium anode protection, a consistent capacity of 600 mAh/g is preserved for more than 200 cycles. This study reveals that in most operation conditions, the destabilization of the lithium anode is more critical for the cycle life than the poor reversibility of air-cathode reaction. The present study can also be readily applicable to many other rechargeable batteries that suffer from similar interfacial degradation by side products from the other electrode.

Fig. 1. Comparative schematic illustration of lithium-oxygen cells with (a) conventional polyolefin porous PE separator and (b) poreless PU separator. (c) The cycling performance of the PE, PU, PE+LiI, and PU+LiI cells at a current density of 200mA/g with a fixed capacity of 600 mAh/g. The inset shows XRD spectra and color changes of the Li metals of PE and PU cells after 70 and 100 cycles, respectively.

References

[1] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J.-M. Tarascon, Nat. Mater. 11 (2012) 19-29.

[2] L. Grande, E. Paillard, J. Hassoun, J.-B. Park, Y.-J. Lee, Y.-K. Sun, S. Passerini, B. Scrosati, Adv. Mater. 27 (2015) 784-800.

[3] R. S. Assary, J. Lu, P. Du, X. Luo , X. Zhang, Y. Ren, L. A. Curtiss, K. Amine, ChemSusChem 6 (2013) 51-55.

Figure 1
Integral-Type Porous Cobalt@Cobalt Oxide Anode with Micro/Nano-Sized Pores for Lithium-Ion Battery
Authors: Park Hyeji , Kim Kyungbae , Cho Hunhui , Kim Jae-Hun , Dunand David C. , Choe Heeman
Published: February 2020

The integrated porous Cobalt@Cobalt oxide anode was prepared by facile processes including freeze-casting and thermal-oxidation for use as high-capacity anode material of lithium-ion battery. The three-dimensional Co foam with elongated, aligned micropores was synthesized by a freeze-casting process. Subsequently, it was heat-treated in order to form cobalt oxide material with nano-structure on the surface of the Co foam. In this electrode design, the hierarchical three-dimensional Co foam was used as current collector and nanowall-like cobalt oxide layer acted as anode that reacts with lithium ions during discharging and charging. The integrated porous Cobalt@Cobalt oxide anode exhibits highly reversible capacity of 1200 mAhg-1 even after 45 cycles with an initial coulombic efficiency of 79.1%, which is much higher than that of the conventional cobalt foil anode (259 mAhg-1). The integrated porous Cobalt@Cobalt oxide anode, which was fabricated in this study, has promising potential applications as a self-supporting advanced anode architecture with high capacity for lithium-ion battery.
Sustainable Redox Mediation for Lithium-Oxygen Battery By Using Protected Lithium Anode
Authors: Lee Hongkyung , Lee Dong Jin , Kim Yun-Jung , Noh Hyungjun , Lee Jinhong , Park Jung-Ki , Kim Hee-Tak
Published: February 2020

Because of the growing needs for secondary batteries with greater energy density in various applications including electric vehicle, rechargeable non-aqueous lithium–oxygen (Li-O2) battery is receiving a great attention owing to its high theoretical energy density of 3505 Wh kg-1 which far exceeds that of conventional lithium ion battery (LIB) [1, 2]. However, due to the insulating nature of main discharge product, lithium peroxide (Li2O2) the oxygen-evolving reaction (OER) during charge requires a much higher overpotential, which is the one of the main challenges to practical applications [2, 3]. Incomplete decomposition of Li2O2 at the cathode causes excessive accumulation of solid discharge products on cathode surface during cycling, resulting in cell failure by pore clogging. As a consequence, Li-O2batteries usually present poor round-trip efficiencies and severe capacity decays. To alleviate this problem, redox mediators (RMs) as soluble and mobile catalyst in aprotic media, have been intensively studied to address the overvoltage problem [3, 4]. In spite of such a smart strategy, self-discharge of redox mediator is inevitable in current battery configurations due to its chemical reduction at Li metal anode, as shown in Figure 1.

In this presentation, we suggest a synergic combination of soluble redox mediator and protected Li metal electrode for preventing the self-discharge of redox mediator and realize the concept by exploiting a redox mediator of 2,2,6,6,-tegramethylpiperidinyl-1-oxyl (TEMPO) and a composite protective layer (CPL) of Al2O3/PVdF-HFP composite. First, from the electrochemical characterization in conjunction with SEM and XPS analyses, the effectiveness of the highly reversible TEMPO/TEMPO+ redox couple as a RM was verified. More importantly, this presentation provides a detrimental effect of TEMPO on the interfacial stability of Li metal electrode by monitoring the battery cycling under Ar atmosphere, and thus, the necessity of Li metal anode protection was suggested in terms of the reversibility of RMs in the non-aqueous media. The CPL coated on Li metal electrode could suppress the reaction of TEMPO at Li metal electrode and maintain the redox mediated Li2O2 oxidation over repeated cycles, opening a new possibility for a robust use of RM for Li-O2batteries.

Figure 1. Schematic illustration of (a) the self-discharge of redox mediator in Li-O2 battery and (b) the CPL-coated Li electrode which prevent the reaction between redox mediator and Li metal electrode.

References

[1] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J.-M. Tarascon Nat. Mater.
2012, 11, 19-29.

[2] G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson, W. Wilcke J. Phys. Chem. Lett.
2010, 1, 2193-2203.

[3] Y. Chen, S. A. Freunberger, Z. Peng, O. Fontaine, P. G. Bruce Nature Chem.
2013, 5, 489-494.

[4] B. J. Bergner, A. Schürmann, K. Peppler, A. Garsuch, J. Janek J. Am. Chem. Soc.
2014, 136, 15054-15064.

Figure 1
The Carbon-Free RuO2-TiO2 Electrode for Li-Air Batteries
Authors: Park Jin-Bum , Belharouak Ilias , Lee Yun Jung , Sun Yang-Kook
Published: February 2020

Li-O2 batteries offer the highest energy density among rechargeable batteries. This superb energy density makes the system one of the most attractive energy storage devices for electric vehicles (EV), energy storage systems (ESS), and other applications1 where high energy density is the most important figure of merit. There remain many challenges, however, for the practical application of Li-O2 batteries including low energy efficiency caused by the large energy loss during Li-O2 electrochemical cycles. The widely-accepted theoretical reaction of Li-O2 batteries is 2Li+ + O2 + 2e- ↔ Li2O2. The forward direction forming Li2O2 represents the discharge process and the reverse reaction of Li2O2 decomposition the charge process; however, many parasitic reactions have been reported, especially involving electrolyte and carbon materials.2 These undesired side reactions significantly reduce the round-trip efficiency of Li-O2 batteries. Carbon in particular, the most common material for air electrodes because of its high surface area and good electrical conductivity, may react to Li2CO3 in Li-O2 cells that impede the reversible Li-O2 reaction.2

Some of the alternative cathode materials suggested recently include TiC,3 indium tin oxide (ITO).4 Bruce and his co-workers3 ascribed the stability of TiC cathodes to the surface TiO2 layer on TiC. The TiO2 surface layer was stable from the attack of oxygen radicals during cycling. Recently, TiO2 nano tubes have been explored as a support for electrocatalysts.5 The resulting cells showed enhanced cycle life due to the higher stability of TiO2 when compared with carbon materials. The Pt or RuO2 catalyst-loaded TiO2 nanotube exhibited an enhanced cyclability with low charge potentials, especially under high current density. Despite the high specific capacity in their research, however, the actual capacity of Li-O2 batteries was not sufficient for practical application, since the specific capacity was calculated based on the catalyst loading mass, which is only 0.1 mg on a 15 mm support. Li-O2 batteries must be highly reversible with a high cell capacity for high energy applications.

Here, we synthesized RuO2/mesoporous TiO2 composites, abbreviated as RuO2/mTiO2, and used as a cathode material for Li-O2 batteries. A carbon-free electrode of RuO2/mTiO2 showed 4 mAh of cell capacity with alow charge potential of under 4 V.

References

1. J. Lu, L. Li, J.-B. Park, Y.-K. Sun, F. Wu, K. Amine, Chem. Rev. 114, 2014, 5611-5640.

2. B. D. McCloskey, A. Speidel, R. Scheffler, D. C. Miller, V. Viswanathan, J. S. Hummelshøj, J. K. Nørskov, A. C. Luntz, J. Phys. Chem. Lett. 3, 2012, 997-1001.

3. M. M. Ottakam Thotiyl, S. A. Freunberger, Z. Peng, Y. Chen, Z. Liu, P. G. Bruce, Nat. Mater. 12, 2013, 1050-1056.

4. F. Li, D. M. Tang, Y. Chen, D. Golberg, H. Kitaura, T. Zhang, A. Yamada, H. Zhou, Nano Lett. 13, 2013, 4702-4707..

5. G. Zhao, F. Mo, B. Wang, L. Zhang, K. Sun, Chem. Mater. 2014, 26, 2551-2556.
Polymer Encapsulated Sulfur Nano-Composite for Long Cycle-Life Lithium Sulfur Battery
Authors: Ansari Younes , Zhang Sonia , Chiang Yet-Ming
Published: February 2020

The lithium-sulfur (LiS) battery is of great interest owing to its remarkable theoretical capacity of 1672 mAh g-1 and specific energy of 2600 Wh kg-1.  The low operating voltage of the LiS battery (~2.0 V) provides safety advantages over high-voltage cathode materials, and elemental sulfur is environmentally friendly and inexpensive.  However, well-known issues in Li-S batteries include the loss of electrical contact, low electronic conductivity of sulfur, and shuttling of polysulfides during cycling.  The shuttle effect is known to cause the low utilization of the sulfur, degradation of cycle-life and, low Coulombic efficiency in LiS batteries.

Using conductive materials to encapsulate sulfur nano-particles to improve the electronic conductivity of sulfur and limit the polysulfide dissolution is one of the striking strategies for the development of LiS batteries of long cycle-life and high Coulombic efficiency (above 95%).  Most polymer-encapsulated nanocomposites reported thus far require low-temperature treatment as well as long synthesis time, and have short cycle life barely exceeding 100 charge/discharge cycles.  Here, we demonstrate that by controlling the pore size of the encapsulating polymer membrane, we can achieve significant improvement in the cyclability and Coulombic efficiency of an Li-S battery.  Polyaniline is used as the encapsulating polymer membrane since it reacts with sulfur at high temperature to form a cross-linked structure, which is known to significantly improve the cycling performance. Morphology of the polymer may be controlled by intercalation of metal oxide nano-particles (e.g., MnO2, ZrO2, TiO2) into the pores of the porous polyaniline (PAN) as the encapsulating polymer. To accommodate the large volumetric expansion of sulfur during lithiation, sufficient empty space can be provided by heat treatment of the sulfur/PAN nano-composite.

Up until now, the sulfur/PAN nano-composites production has required low- temperature treatment of reactants for 24-48 hours under nitrogen or argon atmosphere. As a unique advantage, we provide a simplified short-time (3 hours) synthesis method at room temperature under air atmosphere.

Acknowledgment: This work is supported as part of the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.
Intermediate Temperature Molten Salt Lithium Batteries, New Chemistries and Beyond
Authors: Giordani Vincent , Chase Gregory V , Uddin Jasim , Tan Hongjin , Tozier Dylan , Burke Colin M , Greer Julia R , McCloskey Bryan D , Addison Dan
Published: February 2020

A current focus in battery research, particularly for electric vehicles and stationary energy storage applications, is identifying new chemistries that could enable a higher energy density and lower cost battery than currently available Li-ion batteries. Li-ion electrode materials, which dictate attainable battery energy densities, used in these batteries have changed little in the past decades, and therefore physical limits in Li-ion battery pack energy density are being approached given the enormous development efforts in the field.  In this work, we take a close look at molten salt lithium batteries and in particular alkali metal nitrate/nitrite molten salt electrolytes which exhibit low melting point temperature, high ionic conductivity, high thermal stability and good interfacial properties against lithium metal anode. More specifically, we investigated the O2 electrode electrochemical behavior as well as the reduction of nitrates on metal and metal oxide nanoparticles to form lithium oxide and nitrites. The results reported herein provide a potentially transformative approach to enable a rechargeable Li-O2 battery chemistry through the use of inorganic molten salts as electrolytes. Building on our previous foundational research, in which we identified that all organic electrolytes are incompatible with the reversible Li-O2 electrochemistry, the electrolyte compositions reported here do not contain unstable organic solvents. As a result, the reversibility of the Li-O2 electrochemistry reported here is unprecedented.  Another approach developed at Liox Power, Inc. is the use of nitrates as electroactive material, or in other words, as both the electrolyte and the cathode material. In this case the battery discharge reaction proceeds as the electrochemical reduction of nitrate anions NO3
- present in the electrolyte phase. High Li+ and NO3
-concentration and ionic conductivity allow extremely fast kinetics at 150 °C resulting in very low discharge overpotentials. Furthermore, we demonstrate that such electrochemical reaction is reversible and lithium oxide particles (octahedron equilibrium Wulff shape) can be recharged with energy efficiencies greater than 97%.

Figure 1. Top, voltage profile (first 2 cycles) of a cell employing a Li metal anode, a LiNO3-KNO3 eutectic and a Ni cathode, cycling at 150 °C at 0.32 mA/cm2, under Ar gas. Bottom, voltage profiles of (black) organic electrolyte Li-O2 cell and (red) LiNO3-KNO3 molten salt Li-O2 cell; both cells used a Li metal anode, a Super P carbon black cathode (5% PTFE binder) and cycled at 0.32 mA/cm2 under pure O2 gas.

Figure 1
High Rate Performance Spinel-Layered Based Li-Rich Compounds As Cathode Materials for Next Generation Lithium-Ion Batteries Application
Authors: M Subramaniyam Chandrasekar , Tai Zhixin , Liu Hua Kun , Dou Shi Xue
Published: February 2020

A quest to hunt for reliable, cost-effective and high rate performing materials constitute the hot topic in applications for lithium-ion batteries (LiBs) in hybrid/plug-in electric vehicles.  In order to foresee these objectives, herein, we have attempted to synthesis spinel-layered Li-rich Li-Mn-M-O based compound as cathode material for lithium-ion batteries applications via simple, low temperature - solvothermal method. Both as-obtained and annealed samples were characterized for their phase, morphology using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. When electrochemically tested against Li+/Li0 between 2.0 – 4.8V, the annealed Li-rich spinel-layered exhibited excellent specific capacity and rate capability even at high current density, making it as a probable next generation cathode material for LiBs application.
Effects of the Chemical Structure of Thickening Agent on the Dispersion and Electrochemistry of Li-Ion Batteries
Authors: Li Chia-Chen , Chen Meng-Fu , Rohan Rupesh , Lee Jyh-Tsung
Published: February 2020

To make electrode sheets for lithium-ion (Li-ion) cathodes or anodes with appropriate mechanical properties, the electrode-active material and conductive agent generally have to be blended with specific polymeric binders. To mix all the inorganic electrode materials homogeneously with polymeric binder, appropriate solvent that can dissolve the binder is required. According to the type of solvent used, the as-prepared electrode slurry can be classified as two systems – a water-based system and an organic solvent-based system. For environmental consistency and cost considerations, the water-based system, which uses environmentally benign binders and solvents, has attracted increasing attention and has become a new trend in the manufacture of Li-ion electrodes. Among water-compatible polymers, the aqueous emulsion of styrene-butadiene rubber (SBR) is the commonly used binder for electrodes of Li-ion batteries. It is known that SBR provides not only good binding for electrode powders but also the required adhesion of electrode sheets to the current collector. Nevertheless, SBR comes in the form of an aqueous emulsion, which has very low viscosity and, therefore, does not facilitate the wetting of its fabricated electrode slurry on the current collector during casting. To improve the wetting, SBR is generally blended with the thickening agent CMC.

Many studies have shown that using CMC as a thickening agent is beneficial to the rate capability of the as-prepared cathodes but too much addition may cause the corresponding electrode slurries to gel, which the gelled slurries are unavailable for casting. Since CMC contains two kinds of functional groups, carboxyl and hydroxyl groups, it would be interesting to clarify which one of the functional groups causes the gelation of the electrode slurries. Based on the experimental results of replacing CMC by other reagent, such as poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA) and guar gum (GG), it was found that the hydroxyl group rather than the carboxyl group dominates the gelation of CMC in the slurry. Besides to the gelling function, the presence of hydroxyl group in the chemical structure of the thickening agent is also detrimental to the electrochemical performances of as-constructed electrodes and Li-ion cells.
Electrochemical Behavior of Li5FeO4 (LFO) in Energy Storage Applications
Authors: Johnson Christopher , Lin Chi-Kai , Lee Eungje , Su Xin , Lu Wenquan , Trask Stephen E. , Wang Xiaoping , Maroni Victor A. , Ren Yang , Alp Esen E. , Brown Dennis , Krumpelt Michael , Thackeray Michael M. , Chan Maria K. Y. , Kinaci Alper , Li Liang , Yao Zhenpeng , Wolverton Christopher
Published: February 2020

The push for high capacity cathodes capable of Li storage greater than Li/TM (TM=transition metal) ratio of one in Li-ion batteries (LIB) is extremely challenging, but necessary to increase energy densities. The rock-salt layered lithium oxide material, Li2MnO3, is particularly well studied and can release essentially all of its Li during electrochemical charge on the first cycle yielding over 400 mAh/g (cycled >4.6 V vs. Li metal), but this process is irreversible, and capacity rapidly fades. Recently we have been studying the electrochemical behavior of higher lithium-content containing phase, Li5FeO4 (LFO) (a defect anti-fluorite structure, with large lithium content, Li/Fe = 5), in the following three roles: (1) as a reversible 2.8 to 3.0 V cathode, (2) as a Li-source additive to enable Si anode for LIBs, and (3) as a hybrid Li-ion•Li-O2 cathode material.1 As reported by our group, this LFO can provide over 700 mAh/g specific capacity below 4.4 V vs. Li metal2 which now identifies it as an ideal candidate for a myriad of energy storage applications. This poster highlights the LFO material and addresses the following aspects: (1) synthesis of LFO, (2) electrode fabrication, blends and implementation in LIB full cells. The LFO is particularly effective at full cell cycle improvement due to both elimination of high first cycle irreversible capacity losses (ICL), and cycle-to-cycle inefficiencies. Lastly we will back-up our findings through a number of characterization methods in addition to first principles modeling. For example we make use of
novel fast operando Mössbauer spectroscopy
in order to decipher the charge compensation and the stability of tetravalent iron (Fe4+) during real-time cycling of Li/LFO pouch cells. All these results taken together have given us ample understanding of the material, its versatility and extreme effectiveness in energy storage.

[1] L. Trahey, et al., Electrochem. and Solid State Lett., 14, A64 (2011)

[2] C. S. Johnson, et al., Chemistry of Materials, 22, 1263-1270 (2010)

 

This work was supported as part of the Center for Electrochemical Energy Science (CEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Use of the Center for Nanoscale Materials, (Raman) The Advanced Photon Source (operando XRD), and the Electron Microscopy Center (SEM) is supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A Systematic Adhesion Map in Lithium-Ion Battery Electrodes Having Different Design Parameters By Using a Saicas Tool
Authors: Kim Kyuman , Byun Seoungwoo , Cho Inseong , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

When we fabricate a variety of electrodes for lithium-ion batteries (LIBs), some electrode design parameters such as composition, loading level, density, etc. are generally predetermined depending on the targeted energy and power densities. Since they are complexly related to each other, repetitive experiments should be carried out to get reliable long-term cycle life as well as initial capacity. At this point, an optimum binder content or density always remains a difficult question, because there is no systematic research on adhesion properties for LIB electrodes. In addition, only the peel test with the 3M Scotch tape has widely used to compare electrode adhesion strength as a relatively comparing tool. Thus, our group has introduced a tool, the Surface and Interfacial Cutting and Analysis System (SAICAS), to measure shear stress as well as adhesion strength of the LIB electrodes [1-3]. Although our previous works provided battery scientists and engineers with worthwhile data, more systematic investigation to separate intrinsic adhesion property from loading is greatly required.

Herein, we applied the SAICAS tool to measure all the adhesion properties of LIB LiCoO2 electrode having three different loading levels, 5, 10, and 15 mg cm-2, and four different electrode densities, 2.0, 2.5, 3.0, and 3.5 g cm-3. Not only the adhesion strength between current collector and electrode coating layer, but also the adhesion strength at the middle of the electrode coating layer are obtained and compared to divide each intrinsic adhesion strength independent of loading effect. From those data, we could propose an empirical equation to predict adhesion strength if density and loading level are provided. This equation is also confirmed in the LiCoO2 electrode system by comparing the adhesion strength of arbitrary electrodes with different loading and density.

Acknowledgements

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977).

References

[1] Son, B.; Ryou, M.-H.; Choi, J.; Lee, T.; Yu, H. K.; Kim, J. H.; Lee, Y. M., Measurement and Analysis of Adhesion Property of Lithium-Ion Battery Electrodes with SAICAS. ACS Appl. Mater. Interfaces 2013, 6, 526-531.

[2] Choi, J.; Ryou, M.-H.; Son, B.; Song, J.; Park, J.-K.; Cho, K. Y.; Lee, Y. M., Improved High Temperature Performance of Lithium-Ion Batteries through Use of a Thermally Stable Co-Polyimide-Based Cathode Binder. J. Power Soures 2014, 252, 138-143.

[3] Choi, J.; Kim, K.; Jeong, J; Cho, K. Y.; Ryou, M.-H.; Lee, Y. M., Highly Adhesive and Soluble Co-polyimide Binder: Improving the Long-Term Cycle Life of Silicon Anodes in Lithium-Ion Batteries, ACS Appl. Mater. Interfaces, 2015, 7, 14851-14858

Figure 1
A Single-Lithiun-Ion Conductor Coordinated Porous Pvfm-Peg Based Membrane and Plasticizer As Electrolyte for Lithium Ion Batteries
Authors: Lian Fang , SUN Xiaomeng
Published: February 2020

Polymer electrolyte comprised of lithium dissolved in polymer matrix has draw great attention due to its safety as well as processability, flexibility and lightweight. The dissociation of binary lithium salt in polar polymer matrix gives rise to so called bi-ionic conductors in which both cations and anions migrate as charge carriers. But unfortunatelly, a serious concentration polarization takes place in bi-ionic conductors due to the buildup of the anions at the electrode/electrolyte interface[1]. In order to solve the above problem, a single ion conductive polymer electrolyte has been proposed, in which the counter anions are tethered to the polymer backbone or immobilized in a matrix, eliminating polarization loss and enabling the passage of larger currents through the cells[2]. Until recently, single ion polymer electrolytes reported show low ambient temperature ionic conductivities (<10-6S·cm-1) due to the strong interaction between cations and their immobile matrixes[3].

A single-ion conductive hybrid electrolyte of porous PVFM-PEG based membrane and the optimized PC/EC (1/1, vol) mixed solvent as plasticizer was fabricated. The membrane and its electrolyte were characterized using scanning electron microscopy (SEM), stress-stain test, linear sweep voltammetry (LSV), ionic conductivity and lithium ion transference number measurement. The results indicate the combination of optimized PC/EC (1/1 in vol) plasticizer and porous PVFM-PEG based membranes[4] contributes to a considerable enhancement of room-temperature conductivity  to 1.59×10-4S/cm. At the same time, lithium ion transference number of hybrid electrolyte based on the porous PVFM-PEG electrolyte membranes increased to 0.76. The assembled cells from the hybrid electrolyte also show wide electrochemical stability window and excellent cyclability.

Reference

[1] Bouchet R, Maria S, Meziane R, et al. Single-ion BAB triblock copolymers as highly efficient electrolytes for lithium-metal batteries[J]. Nature materials, 2013, 12(5): 452-457.

[2] Sinha K, Wang W, Winey K I, et al. Dynamic Patterning in PEO-Based Single Ion Conductors for Li Ion Batteries[J]. Macromolecules, 2012, 45(10): 4354-4362.

[3] Kobayashi N, Uchiyama M, Tsuchida E. Poly [lithium methacrylate-co-oligo (oxyethylene) methacrylate] as a solid electrolyte with high ionic conductivity[J]. Solid State Ionics, 1985, 17(4): 307-311.

[4] Fang Lian, Hong-yan Guan, Yan Wen, Xiao-rong Pan, Polyvinyl formal based single-ion conductor membranes as polymer electrolyte for lithium ion batteries, Journal of membrane science 2014, 469, 67-72
Superior Capacity Retention of Lithium Sulfur Batteries with Nano-Sized TiO2-Embedded Polymer Electrolyte
Authors: Hwang Bing Joe , Lee Felix , Tsai Mon-Che , Lin Ming-Hsien , Ni'mah Yatim Lailun , Hy Sunny , Kuo Chao-Yen , Cheng Ju-Hsiang , Su Wei-Nien
Published: February 2020

A lithium sulfur battery with superior capacity retention is unexpectedly achieved by using a nano-sized TiO2-embedded polymer electrolyte. Computational results based on bonding interaction and Raman characterization of the different components reveal the undesired shuttle mechanism causing the passivation of Li anode can be suppressed due to the preferential adsorption effect of the nano-sized TiO2 to the polysulfides. This configuration can deliver more than 1450 mAh/g for the first discharge capacity with ~87% capacity retention after 100 cycles versus 38% in the absence of TiO2 due to the inhibition of polysulfide species passivated on the lithium anode. Thus, it provides an opportunity of overcoming today’s new technological system issue.
Materials for High Energy Density and Long-Life Lithium-Sulfur Batteries
Authors: Bugga Ratnakumar V , Jones Simon C. , Jones John-Paul , Pasalic Jasmina , Torres Loraine , Addison Dan , Thiallaiyan Ramanathan
Published: February 2020

Lithium ion batteries have been successfull deployed in several NASA missions since 2000, including the Mars Exploration Rovers (Spirit and Opportunity), Mars Science Laboratory (MSL), Pheonix Lander, JUNO, Aquarius, Keppler Rovers and SMAP. Being compact, lightweight and durable, these batteries have contributed to significant enhancement or even enablement of these missions. However, NASA’s future missions, i.e. small planetary rovers, planter probes, small satellites, CubeSats etc., warrant more efficient battery technologies, ‘beyond Li-ion,’ with higher energy densities. The lithium-sulfur system emerges as the most promising technology because of its high theoretical specific energy (3-4x) compared to Li-ion cells.  To address the needs of the future missions, NASA has initiated projects to develop high-energy and long-life lithium-sulfur cells, with a high cell specific energy of 400 Wh/kg, good cycle life of 300 cycles and an ability to operate safely over a wide temperature range of -10 to +30 °C. Despite its high theoretical energy densities and significant developmental efforts in several laboratories, Li-S technology hasn’t matured yet, mainly due to challenges related to the leaching of reduced products into the electrolyte forming a redox shuttle and also poisoning the lithium anode. Several attempts are being made in the literature to develop cathode designs, e.g., hierarchical porous carbon structures to sequester sulfur and its reduction products, and also electrolyte solutions to minimize their solubility. 1-5 In a similar manner, we have developed improved cell components for Li-S cells,6 i.e., i) new sulfur cathodes with metal sulfide blends that show high specific capacities of ≥800 mAh/g at C/3 rates with high material loadings required for achieving high specific energy and energy densities, ii) Li anode protected with suitable polymer electrolytes that display efficient Li cycling and durability in laboratory Li-S cells, and iii) Electrolytes with co-solvents electrolyte additives and iv) new proprietary electrode coatings serving as polysulfide blocking layers to inhibit the deleterious effects of sulfur redistribution and contribute to a good cycle life.  In this paper, we will describe some of these material developments and their electrochemical behavior in three-electrode cells and performance in laboratory pouch.

Y. Yin, S. Xin, Y. Guo and L. Wan, Angew. Chem. Int. Ed. 2013, 52, 13186 (2013).

S. Evers, L. F. Nazar, Acc. Chem. Res., 46, 1135 (2013);

X. Ji, K. T. Lee, L. F. Nazar, Nat. Mater. 8, 500 (2009).

A. Manthiram, S.-H. Chung, C. Zu, Adv. Mater. 27, 1980 (2015).

S. S. Zhang, Front. Energy Res. 1, 1 (2013).

Ratnakumar Bugga, Simon Jones, Jasmina Pasalic, Dan Addison and Ramanathan Thillaiyan, 228th ECS Meeting, Phoenix, AZ, Oct. 11 (2015)
Efficient "on-the-Fly" Calculation of Raman Spectra from Ab-Initio Molecular Dynamics: Application to Lithium-Sulfur Batteries
Authors: Partovi-Azar Pouya , Kühne Thomas D. , Kaghazchi Payam
Published: February 2020

We present a novel computational method to accurately calculate Raman spectra from first principles. Together with an extension of the second-generation Car-Parrinello ab-initio molecular dynamics  (AIMD) method to propagate maximally localized Wannier functions along with the nuclei, a speed-up of one order of magnitude can be obtained. Due to expression of the total polarizability as a sum of Wannier polarizabilities, the method also enable us to find partial Raman activities corresponding to local vibrations of different fragments in the system.

We have used this method to investigate the Raman spectra of (Li2S4)𝑛, 𝑛=1,4,8 clusters which are believed to be the last intermediates in the S8→Li2S transition in lithium-sulfur (Li-S) batteries, during the discharge cycle. However, it is not fully established whether or not any other products coexist with the Li2S crystal in the discharged state. In this study, we have observed a clear evidence of Li2S4→Li2S2 transition by investigating the systematic changes in the simulated Raman spectra as the cluster size increases. In line with recent experiments, we found that the Raman-active sulfur-sulfur stretching mode at 440 cm-1 can be considered as a signature of covalent bonding between two and more sulfur atoms per formula. We have also demonstrated that the transition is mainly due to the strong electrostatic interactions between polar Li2S4 monomers which result in energy lowering by arranging the local dipole moments in anti-parallel fashion. This arrangement result in the formation of crystal-like Li2S2 structures at the interfaces of Li2S4 monomers. 

Furthermore, through minimum-energy conformation search combined with AIMD simulations, we have shown that upon carbonization of polyacrylonitrile in early discharge stages of Li-S batteries and further exposure of the product to octasulfur, S2 groups form a bridge between two consecutive nitrogen atom on the edge of carbon fiber. Moreover, our Raman simulations reveal a characteristic Raman activity for these -N-S-S-N- groups in 300 - 400 cm-1 frequency range, in form of two distinct peaks which researchers could not experimentally assign before. Finally, we will discuss our recent studies on structure of complex cathode materials using our approach together with experimental measurements.
Computation-Guided Design of Interface Engineering in All-Solid-State Li-Ion Batteries: A First Principles Study
Authors: Mo Yifei
Published: February 2020

All-solid-state Li-ion battery based on solid electrolyte materials is a promising next-generation Li-ion battery technology with intrinsic safety, high energy density, and enhanced cyclability. The key problem in enabling this new battery technology is the high interfacial resistance and interfacial degradation at the solid electrolyte-electrode interfaces. In this presentation, I will show how we use computational modeling to provide unique insights into the fundamental mechanisms at these buried interfaces, which are difficult to access in experiments. I will first demonstrate using first principles computation to predict various materials properties of the solid electrolyte materials with little experimental input. In addition, we systematically investigate and compare the electrochemical stability and chemical stability of the solid electrolyte-electrode interfaces, and study how these interfaces affect the interfacial resistance, low cyclability, and mechanical failure in all-solid-state Li-ion batteries. Our computation results suggest the formation of decomposition interphase layers in all-solid-state Li-ion batteries and the significant effects of the interphase layers on the electrochemical performance of the all-solid-state Li-ion batteries. Different interfaces between solid electrolyte and electrode materials may have different problems at the interfaces, which require different interfacial engineering strategies to resolve. The mechanisms of artificial layers to improve the interfacial properties are revealed by our computation. This computational study provides novel insights and general guidance for interfacial engineering in all-solid-state Li-ion batteries.
Potential-Dependent Mechanism of Li Diffusion in Li2s for Li-S Batteries
Authors: Moradabadi Ashkan , Kaghazchi Payam
Published: February 2020

Li2S is the final product of lithiation of sulfur cathode in Li-S batteries. Mechanism of Li diffusion in Li2S has not been studied so far. Such a study can help us to understand the origin of (measured) lower capacity of sulfur cathodes in comparison with the theoretical capacity. In this presentation, I will discuss formation energies of a variety of possible defects and their diffusion mechanisms in Li2S. We found that the pathway and energy barrier of Li diffusion in Li2S is potential dependent. 

To our knowledge, such a result has not been reported so far in any other electrode materials. Our results show that Li(2-δ)S (Li-vacancy-rich) is the most favorable defective structure of Li2S for the voltage ranges between 0.93 V and 2.03 V (widely-used operating voltage range of Li-S batteries). In this case, the vacant sites are dominant defect sites and Li diffusion occurs via single vacancy with relatively low energy barrier of 270 meV. However, Li(2+δ)S (interstitial-Li-rich) may also exist as a metastable phase at high cycling rates (far from equilibrium). Considering the fact that the lithiation of S cathodes is an intraparticle two-phase (core/shell S/Li2S) growth process, we conclude that lithiation of metastable S/Li(2+δ)S particles may be strongly hindered because of the high energy barrier of 450 meV for Li diffusion (via the exchange mechanism) within the Li(2+δ)S shells.

Figure 1
In Situ Characterization of Li Transport with Neutrons
Authors: Liu Danny X. , Co Anne C. , Lyons Daniel Joseph , Cao Lei Raymond
Published: February 2020

We have recently developed a nondestructive method to visualize and quantify Li atom position in real-time using neutrons by a method referred to as neutron depth profiling (NDP).  In situ NDP is an ideal technique for probing Li complex formation, accumulation and transport within the battery material during charge/discharge.  Currently, our work is focused on understanding the effect of an electrochemical event to the materials’ storage properties.  Specifically we report our recent work on the preferential Li nucleation, Li trapping and Li transport in intermetallic materials like LixSny, LixSiy and LixAly and intercalating materials like LiNiMnCoO3.
High Performance Iron-Doped LiMnPO4 Cathode Material for Lithium-Ion Batteries
Authors: Wang Liguang , Zuo Pengjian , Yin Geping , Wang Jiajun , Wang Jun
Published: February 2020

Olivine-type LiMPO4 (M = Fe, Mn, Co, Ni) has become of great interest as cathodes for next-generation high-power lithium-ion batteries. LiMnPO4, possessing a moderate working voltage compatible to the present electrolyte systems, can provide a higher energy density than LiFePO4 on account of its higher redox potential of Mn3+/Mn2+ (4.1 V) than Fe3+/Fe2+ (3.5 V). However, the electrochemical performance of LiMnPO4 is poor due to the slow lithium diffusion kinetics within the grains and the low intrinsic electronic conductivity, even much worse than those of LiFePO4. Up to now, low electronic conductivity can be successfully overcome by modifying the LiMnPO4 particles with carbon and minimizing particle size. The mesoporous and hollow sphere structure can further improve the electrochemical performance of olivine-type LiMnPO4 material.

Here, we synthesized the mesoporous hollow sphere LiMn0.8Fe0.2PO4/C composite by a solvothermal method using spherical Li3PO4 as the precursor. The small crystalline size of (~50 nm) LiMn0.8Fe0.2PO4 can reduce the diffusion length for lithium ion transport leading to the enhanced rate capability. The mesoporous and hollow sphere structure offers high surface area, which can enhance the electrochemical performance of LiMn0.8Fe0.2PO4/C composite as show in Figure 1. The material exhibits an ultra-long cycle life exceeding 1000 cycles with an extremely low capacity decay of 0.0068 mAh·g-1 loss per cycle, which is the best cycling performance to our knowledge. The results exhibit that the mesoporous hollow sphere LiMn0.8Fe0.2PO4/C composite is a promising cathode material for lithium ion batteries.

Figure 1
Binder Free Mesoporous Spinel Oxides As an Anode Materials for High Performance Li-Ion Battery
Authors: Jadhav Harsharaj S. , Thorat Gaurav M. , Seo Jeong Gil
Published: February 2020

The development of anode material with high specific capacity is the key issue in present lithium ion batteries (LIBs) technology. Recently, transition metal oxides (TMOs), especially cobalt-based oxides with spinel structure have attracted much attention as an anode material for LIBs due to its high theoretical capacity (~700 mAh g-1), long cycle life and high rate performances. In view of the high cost of Co, ternary cobalt oxides via partially substituting Co with less expensive metals, such as Cu, Zn, Ni, Fe, Ni, and Mn, are more practical anode materials for applications. Among these Cu and Zn not only less expensive, but also electrochemically active and contributes to the charge storage. Nevertheless, operation stability and high rating performance are two critical issues needing improvement before wide application of MCo2O4 (M=Cu, Zn) can be realized. However, the limitations of TMO materials could be possibly overcome by tailoring morphology and pore size distribution to sustain structural disintegration during cycling and promote lithium ion storage. Herein, flower-like and microsphere MCo2O4 (M=Cu, Zn) were synthesized by hydrothermal strategy with porous structure.

A facile urea-assisted hydrothermal method and subsequent calcination for 2 h was pursued to obtain pure flower-like and microsphere MCo2O4 (M=Cu, Zn) samples. The Ni-foam was used as substrate for in-situ deposition MCo2O4 (M=Cu, Zn). The obtained flower-like and microspheres morphology was assembled by nanorods, and the nanorods were comprised of interconnected particles with a porous structure. The important properties of electrode material such as morphology, size, surface area, porosity, pore size distribution highly desirable for its high performance. The desirable electrochemical performance of MCo2O4 (M=Cu, Zn) clearly indicates it is promising candidates as an anode material for LIB. This work was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant number: NRF-2013R1A1A2060638 and No. 2009-0093816).
High Capacity Li-Ion Anodes with Tunable Rate Capability Comprised of Si-Ge Branched Nanowire Heterostructures
Authors: Kennedy Tadhg , Ryan Kevin M
Published: February 2020

Li-alloying nanowires (NWs) are promising anode materials for next generation lithium-ion batteries due to their large maximum theoretical capacity when compared with conventional graphitic based materials (372 mAh/g). Ge NWs, in particular, have shown great promise, exhibiting stable capacities of 900 mAh/g over 1000s of cycles and excellent rate capability due to the high rate of diffusivity of Li in Ge and its inherent high conductivity.1, 2 The superior capacity retention of Ge is attributed to the complete restructuring of the NWs that occurs within the ﬁrst 100 cycles to form a continuous porous network that is mechanically robust. The possibility of incorporating Si into this stable network of Ge is very appealing, combining the very high capacity of Si with the excellent rate characteristics and capacity retention of Ge.

Here we report the formation of high-performance and high-capacity lithium-ion battery anodes from high-density Si-Ge heterostructure nanowire arrays grown directly from the current collector.3 The unique morphology of the active material consists of Si NW branches grown from a Ge NW backbone. By tuning the ratio of Si to Ge in the material it is possible to design electrodes for either high-capacity applications (high Si : Ge mass ratio) or high rate capability applications (high Ge : Si mass ratio). We show by ex-situ high-resolution transmission electron microscopy (HRTEM) and high-resolution scanning electron microscopy (HRSEM) studies that the NW array transforms into a mechanically robust, porous network of Si and Ge ligaments. Once this network is formed it is highly stable, maintaining capacities of 1700 mAh/g over 100 cycles. The electrode material described here also has the advantage of being formed in a low energy, rapid synthetic protocol. Using a very simple reaction protocol, NW growth occurs by thermolytic decomposition of an organometallic precursor onto a preheated substrate in an inert atmosphere.

1. Kennedy, T.; Mullane, E.; Geaney, H.; Osiak, M.; O’Dwyer, C.; Ryan, K. M. Nano Lett.
2014, 14, (2), 716-723.

2. Mullane, E.; Kennedy, T.; Geaney, H.; Ryan, K. M. ACS Appl. Mater. Interfaces
2014, 6, (21), 18800-18807.

3. Kennedy, T.; Bezuidenhout, M.; Palaniappan, K.; Killian Stokes; Brandon, M.; Ryan, K. M. ACS Nano
2015, 9, 7456–7465.

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Porous Three-Dimension Activated Reduced Graphene Oxide As Anode Materials for Lithium Ion Batteries
Authors: Zhu X , Wei M , Wu S , Zuo L , Qu X , He L , Zhong Y , Zhu Y
Published: February 2020

A porous reduced graphene oxide, with a Brunauer-Emmett-Teller surface area of up to ~ 3120 m2 g-1, is prepared by using chemical activation of microwave exfoliated graphite oxide. The sp2-bonded carbon has a continuous three-dimensional network of highly curved atom-thick walls with ~ 1 to 5 nm width pores. As an anode material for lithium ion battery, it can deliver a reversible specific capacity of 1603.4 mAh g-1. To understand the Li storage mechanism, the porous carbon samples with specific surface area tunable are investigated. The high reversible capacity indicates that the meso- and micropores are the key factor for Li insertion/extraction during discharge and charge. The porous structure and large specific surface area is believed to have contributed to the high performance.

Figure 1
High Performance Li-Ion Capacitor Laminate Cells
Authors: Cao Wanjun , Luo Jifan , Yan Jin , Chen Xujie
Published: February 2020

High performance Li-ion capacitor (LIC) laminate cells have been fabricated with activated carbon positive electrodes (PEs) and hard carbon/lithium stripes negative electrodes (NEs). The LIC laminate cells can achieve a maximum specific power of 6 kW kg-1 and a maximum power density of 12 kW L-1. The specific energy and energy density of the LIC laminate cells are 14 Wh kg-1 and 28 Wh L-1 respectively, which is about 3 times of the traditional electric double layer capacitors (EDLCs). The DC life of such LIC cell has passed 2000 h testing while held at maximum operation voltage 3.8 V and 65 °C. Extended cycle performance under 50C rate of the LIC laminate cell has been tested: such LIC can remain 89% of the original discharge capacitance after 100,000 cycles without obvious changes in ESR value. When the LIC cell is charging and discharging under 125C rate, the cycle life is still more than 50,000 cycles.

Figure 1