bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Li-Ion Diffusion Studies of Li6Hf2O7 As Solid-State Electrolyte for Li-Ion Batteries
Authors: Amores Marco , Cussen Edmund J , Corr Serena A
Published: February 2020

Development of safe Li-ion batteries with high operating voltages and enhanced capacities is the keystone for the development of high energy density demand in emerging technologies such as the electric car. Current Li-ion batteries involve the use of flammable organic solvents as liquid electrolytes for Li-ions diffusion between the electrodes. These organic solvents present several safety concerns thereby limiting their operating voltage due to potential decomposition. The replacement of these liquid electrolytes with a solid-state electrolyte would overcome not only the safety concerns but the voltage window limit at which the battery could operate. A major requirement in the design of solid-state electrolyte materials is therefore high electrochemical stability and high ionic conductivity.

Here we present the synthesis and electrochemical study of Li6Hf2O7 as a candidate for solid-state electrolyte for next generation Li-ion batteries. Phase pure material was synthesized via a new microwave-assisted solid-state approach.1 In the crystal structure, Hf4+ ions are coordinated with 6 surrounding O2- ions in a octahedral fashion, whereas Li+ ions are located on square-pyramidal interstitial sites.2 Scanning Electron Microscopy images show inhomogeneous sized microparticles without a particular morphology.

Li-ion conductivity has been analysed by electrochemical impedance spectroscopy, with ionic conductivities of 1.42 × 10-2 S cm-1 achieved at 324 oC and a modest activation energy of 0.97 eV, comparable with the isostructural Li6Zr2O7 material.3 Also presented will be our further attempts to substitute on the Hf position to introduce Li-ions on interstitial sites to facilitate the Li hoping diffusion mechanism.4

M. Amores, T. E. Ashton, P. J. Baker, E. J. Cussen and S. A. Corr, J. Mater. Chem. A, 2016. DOI: 10.1039/C5TA08107F

R. Czekalla, W. Jcitschko, Z. anorg. allg. Chcm. 619, 1993, 2038

R. Prasada Rao, M.V. Reddy, S. Adams, B.V.R. Chowdari, Mater. Sci. Eng. B, 177, 2012, 100

Y. Liao, P. Singh, K. Park, W. Li, J. B. Goodenough, Electrochim. Acta 102, 2013, 446            

Figure 1
Substrate Effects on the Cycleability of Metallic Sodium Electrode in Organic Electrolyte
Authors: Yang Yifu , Xu Qian , Shao Huixia
Published: February 2020

Sodium (Na) shares similar chemical properties with lithium (Li) in many aspects, and Na has more positive potential, so it should be able to be used in the majority of the organic electrolytes which have been used in Li ion batteries. More importantly, Na is one of the most abundant elements in the Earth’s crust. Therefore rechargeable sodium batteries are the ideal alternative to LIBs [1-3] in many applications. Na-ion batteries (NIBs) consist of sodium intercalation materials for both positive and negative electrodes, which are electronically separated by electrolyte as a pure ionic conductor. Na ions are cycled back and forth from host electrodes, which is similar to LIBs. This design avoids the use of reactive metallic Na. So the research of NIBs is mainly focused on the development of the cathode materials, and the study of the metallic Na electrode has drawn few attentions in the past. As the Li+ deposition-stripping is crucial to LIBs, the nature of the metallic Na, especially electro-deposition-stripping characteristics, is also worthy of in-depth and systematic research.

In this work, the electrodeposition and stripping characteristics of metallic Na in the electrolyte of 1 mol L-1 NaClO4/EC+DMC (1:1 vol. %) were studied and the deposition-stripping behavior of Na+ on Cu and Sn substrates were compared. The deposition-stripping cycling performances of Na on the substrates were studied through galvanostatic charge-discharge method and cyclic voltammetry. The morphologies of the substrates before and after Na+ deposition were investigated through digital video microscopy. The kinetics of the Na+ electrodeposition on the different substrates was studied through galvanostatic pulse method. The solid electrolyte interface films of Na+ deposits on the substrates were characterized via electrochemical impedance spectroscopy. The results indicate that the nature of the substrate can significantly affect the electrodeposition characteristics of Na+. The high reactivity of metallic sodium with the organic electrolyte solvents and the dendrite formation during metallic Na deposition are even more problematic than metallic Li anodes. Sn is a more suitable substrate than Cu for Na+ electrodeposition due to the formation of Na—Sn alloy during the deposition of Na+.

References

[1] M. D. Slater, D. Kim, E. Lee, C. S. Johnson, Adv. Funct. Mater., 2013, 23, 947.

[2] S. Komaba, W. Murata, T. Ishikawa, N. Yabuuchi, T. Ozeki, T. Nakayama, A. Ogata, K. Gotoh, K. Fujiwara, Adv. Funct. Mater., 2011, 21, 3859.

[3] S. W. Kim, D. H. Seo, X. H. Ma, G. Ceder, K. Kang, Adv. Energy Mater., 2012, 2, 710.

Relating topic:

New Na based Electrodes
Investigation of GeP5 As a High Reversible and Large Capacity Anode Material for Sodium Ion Batteries
Authors: Li Huiqiao
Published: February 2020

Sodium ion batteries (SIB) have attracted more and more research interests recently as a low-cost alternative for LIB. The great challenge is to find proper electrode materials which can satisfy the requirements of commercial application. Among the current reported anodes for SIB, black phosphorus which holds a layered structure and possess high conductivity, can exhibit a large capacity as well as good rate performances, thus becomes the star material in SIB.[1-2] However, the critical requirements of synthesis and low thermo stability of black phosphorus would greatly limit its commercial utilization in battery industry. Recently, we proposed a new phosphorus-like material GeP5 as the anode candidate for SIB. This material possesses a similar two-dimensional layered structure as black phosphorous and graphite.[3] The introducing of Ge element in the layered structure results in an even higher electronic conductivity than black phosphorus. Besides, the chemical and thermo stability of GeP5 is much higher than that of black phosphorus. The higher conductivity and better stability made GeP5 a high performance anode for SIB.

GeP5 can be easily obtained in a large scale by simply mechanical milling of elemental Ge and low cost red P at ambient pressure. In a typical half cell, GeP5 can deliver a reversible discharge capacity of 1200 mAh/g for SIB at a current density of 100 mA/g. The large capacity is attributed to the bi-active components of Ge and P in this material which can both store large capacity of sodium during the charge/discharge processes. More important, the first coulombic efficiency of this material reaches 95%, which is much higher than that of other reported anode materials for SIB and can even compete with the commercial anode in LIB industry. By further treating GeP5 with carbon by high energy ball milling, the obtained GeP5/C nanocomposite demonstrate much enhanced cycle performances and rate capabilities, due to the good volume accommodation effect of carbon matrix in the composite. Profit from the large capacity and low voltage of GeP5, a full cell coupled with a GeP5 anode and a Na3V2(PO4)3 cathode can deliver a high cell voltage and large cell energy density, which shows a promising potential of GeP5 in SIB applications.

References:

[1] J. Qian, Y. Xiong, Y. Cao, X. Ai, H. Yang, Nano Lett., 2014, 14, 1865-1869.

[2] J. Sun, G. Zheng, H. Lee, N. Liu, H. Wang, H. Yao, W. Yang, Y. Cui, Nano Lett., 2014, 14, 4573-4580.

[3] W. Li, H. Li, Z. Lu, L. Gan, L. Ke, T. Zhai, H. Zhou, Energy Environ. Sci., 2015, 8, 3629-3636.
Fabrication of Mesocrystal Nanowire Constructed By Oriented Nanoparticles for Na-Ion Battery and Soft X-Ray Adsorption Spectroscopy
Authors: Hosono Eiji , Asakura Daisuke , Kajiyama Satoshi , Okubo Masashi , Kikkawa Jun
Published: February 2020

For realization of low carbon society, the popularization of electric vehicles and plug-in hybrid vehicles by using high performances secondary batteries is important. Many researchers have studied Li-ion batteries with high energy density and high power density for automotive batteries. Especially, fabrication of nano-materials and development of process for nanostructural control have attracted researchers in industrial and academic fields because the short diffusion length of lithium ions in nanomaterials and high surface area of nanomaterials are suitable for high power density.

We have studied many kinds of nanostructural control processes of active materials for electrodes. In these days, we focus the crystalinity of the materials and easy fabrication processes. We reported fabrication of single crystalline nanowires of LiMnxFe1-xPO4 and mesocrystal nanowires constructed by oriented LiMn0.4Fe0.6PO4 grains by electrospinning methods.1-3 Moreover, we have studied Na-ion batteries, which are expected as low cost secondary batteries because sodium is abundant element.

Here, we report the fabrication of mesocrystal nanowires constructed by Na3V2(PO4)3 oriented nanoparticles by electrospinning method and the battery-performances as Na-ion batteries.4 In addition, we report the soft X-ray adsorption spectroscopy of the materials for understanding about the mechanism of Na insertion/extraction

 

References

[1] K. Kagesawa, E. Hosono, et al., CrystEngComm, 2013, 15, 6638.

[2] K. Kagesawa, E. Hosono, et al., J. Power Sources, 2014, 248, 615.

[3] J. Kikkawa, E. Hosono, et al., J. Phys. Chem. C, 2014, 118, 7678.

[4] S. Kajiyama, E. Hosono, et al., Chem. Eur. J.2014, 20, 12636.
Bridging the Gap Between Supercapacitors and Batteries By a New Material Based on Renewable Ressources
Authors: Fichtner Maximilian , Gao Ping , Chen Zhi , Zhao-Karger Zhirong , Ruben Mario
Published: February 2020

A new material is presented, which is based on an organic natural material and which delivers good specific energy capacities in the order of 190 mAh/g at an average voltage of approx. 3 V. The material can be charged and discharged at rates around 50 C. By a simple modification of the material, the typical issue of organic batteries, the degradation upon cycling, was greatly improved and 80% of the capacity was retained after 10,000 cycles. The material can be used as cathode or anode, or both. Charge and discharge can be done based on Li or other ionic shuttles such as Mg.

Figure 1
Oxygen Selective Membrane for Lithium Air Batteries
Authors: Lu Zhou Guang , Cao Lujie , Liu Ying , Huo Yifeng
Published: February 2020

Lithium air batteries have attracted great recent research interest due to their much higher energy density than that of the currently used Li-ion batteries (3600 Wh kg-1 vs 300 Wh kg-1). However, one of the most critical issues for practical application of Li-air batteries was the contamination of moisture and CO2 from the air. Here we report a high performance O2 selective mixed matrix membrane based on the metal organic framework (MOF) nanocrystallines of CAU-1-NH2@PDA (CAU = Christian-Albrechts-University) and the polymer of polymethylmethacrylate (PMMA). CAU-1-NH2 is a stable metal–organic framework [Al4(OH)2-(OCH3)4(H2N-bdc)3]·xH2O, containing the new Al-containing octameric brick {Al8(OH)4(OCH3)8}12+. It has been found that the obtained mixed matrix membrane (MMM) possessed several advantages including high surface area, controlled porosity, adjustable chemical functionality, high affinity for specific gases and compatibility with polymer chains, making it attractive candidate for selective gas separation. Specifically, the functional group –NH2 in the MOF, –OH in the polydopamine molecule, and the –C=O in the PMMA would preferably interact with CO2 molecule. Also, the intrinsic hydrophobic behaviour of the PMMA polymer can favourably prevent the intrusion of moisture (Fig. 1). These two favourable effects guaranteed the Li-air cell working very stable under ambient atmosphere with very high relative humid (30%) by repelling CO2 and moisture from the air. Evidently, the developed mixed matrix membrane based on CAU-1-NH2@PDA and PMMA polymer opens the way to develop novel air-permeable membrane for real Li-air batteries applied in ambient conditions rather than in pure oxygen (Li-O2) conditions.
Carbon Based Phthalocyanines As Electrocatalysts for Li Air Batteries
Authors: Arul Anupriya , Christy Maria , Moon Kwang Uk , Oh Mi Young , Nahm Kee Suk
Published: February 2020

Li-air batteries are appealing as they offer much higher energy density than the current Li-ion batteries. However, the non–aqueous Li-air batteries suffer from poor cycle life due to electrolyte decomposition and clogging of the air electrode by insoluble discharge products. Efficient bifunctional catalysts could lower the overpotential and improve the stability of Li-air batteries, thus prolonging its cycle life. This study focuses on Iron phthalocyanines (FePc) supported on carbon materials as a solid electrocatalyst for lithium air batteries. Metal phthalocyanines were utilized mainly because of their structural analogy which could be fine- tuned by the metal being used, accessibility, and low cost. The carbon supports such as reduced graphene oxide (rGO) and carbon nanotubes (CNT) were utilized which rendered desirable surface properties like high surface area and high electronic conductivity. FePc/carbons delivered superior electrocatalytic performance for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) comparable and better than that of commercial Pt/C. The bifunctional catalysts were then applied as electrocatalysts in non-aqueous lithium air batteries. The air cells delivered better electrochemical performance mainly by reducing the large overpotential associated with ORR and OER. The cells exhibited better reversibility and cyclability as well. The improved electrocatalytic activity was mainly because of the π–π interaction between carbons and iron phthalocyanines. In addition, the effects of ball milling by ball milling the FePc, and the effects of nitrogen (N2) doping by doping the carbon supports with N2 were investigated. Ball milling has significantly improved the electrocatalytic properties of FePc and N2 doping further enhanced the overall performance.
Molybdenum Disulfide Catalyst for Lithium-Oxygen Batteries
Authors: Asadi Mohammad , Liu Cong , Kumar Bijandra , Phillips Patrick J , Zapol Peter , Klie Robert F , Curtiss Larry A , salehi-Khojin Amin
Published: February 2020

Molybdenum Disulfide Catalyst for Lithium–Oxygen Batteries

Mohammad Asadi1, Cong Liu2, Patrick Phillips3, Peter Zapol2, Robert F. Klie 3, Larry A. Curtiss2, Amin Salehi-Khojin1

1Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA

2Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA

3Department of Physics, University of Illinois at Chicago, Chicago, IL, 60607, USA

   Lithium–oxygen (Li-O2) batteries have been recognized as an emerging technology for energy storage systems owing to their high theoretical specific energy1
-
4. In this study, we discovered a system based on molybdenum disulfide (MoS2) nanoflakes and an ionic liquid (IL) that work together as an effective co-catalyst for discharge and charge in a Li-O2 battery.  Cyclic voltammetry results show superior reaction rates for this co-catalyst at lower overpotentials for both oxygen reduction (15 mV) and evolution (20 mV) reactions compared to Au and Pt metal catalysts under identical experimental conditions. This MoS2/IL co-catalyst also performs remarkably well in the Li-O2battery system with 85% round-trip efficiency and reversibility up to 50 cycles.

   Deferential Electrochemical mass spectroscopy (DEMS), X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR) and Raman experiments were used to elucidate the cell performance.  The results show the fully formation and decomposition of Li2O2 and demonstrate the cell cyclability and stability by the absence of any side products after 50 cycles charge and discharge. Atomic scale characterizations (STEM and EELS experiments) and DFT calculations were used to elucidate the mechanism by which the MoS2 nanoflakes and the ionic liquid electrolyte act together to promote the catalytic properties of the MoS2. The MoS2/IL co-catalyst discovered in this work provides new opportunities for exploiting the unique properties of ionic liquids such as their stability in Li-air batteries as well as activity of MoS2as a cathode material.

 

Zu, C.-X. & Li, H. Thermodynamic analysis on energy densities of batteries. Energy Environ. Sci.
4, 2614 (2011).

Rahman, M. A., Wang, X. & Wen, C. High Energy Density Metal-Air Batteries: A Review. J. Electrochem. Soc.
160, A1759–A1771 (2013).

Zheng, J. P., Liang, R. Y., Hendrickson, M. & Plichta, E. J. Theoretical Energy Density of Li–Air Batteries. J. Electrochem. Soc.
155, A432 (2008).

Shao, Y. et al. Electrocatalysts for Nonaqueous Lithium–Air Batteries: Status, Challenges, and Perspective. ACS Catal.
2, 844–857 (2012).
Investigation on High Energy Density Lithium-Ion Batteries with Long Cycle Life
Authors: Feng Zhen he , Li Wei , Song Jinhua , Liu Xiang , Xie Jingying
Published: February 2020

In order to improve the duration performance of next generation electric vehicle by reducing weight and enhancing cycle life of the batteries[1, 2], a pouch cell named PINP3 with high energy density and long cycle life has been investigated.

The PINP3 was designed based on Nickel-based materials (NCA). The NCA and graphite were respectively used to prepare the positive and negative electrodes. The cell was assembled with three-layer separator and LiPF6based electrolyte. The capacity of the PINP30 is above 3 Ah, with the beginning of life (BOL) energy density of 200 Wh/kg at C/10.

Increasing the initial energy should not be made to the detriment of cell life, which is unfortunately often the case. Cycling at 100% DoD ability is described in Fig.1. More than 3000 cycles performed at the ambient temperature (charge @ C/2 to 4.2V, discharge @1C to 2.75 V). The capacity fade rate is 23.25% and the average capacity loss is only 0.0075% per cycle. The results of characteristics and achieved life tests demonstrate that the PINP3 cell could be the promising candidate for future electric vehicle.

References

[1] Y.K.Sun, S.T.Myung., B.C.Park, J.Prakash, I.Belharouak, K, Amine.Nature Materials.8 (2009)320-324

[2] Richard Van Noorden.Nature.507 (2014)26-28.

Figure 1
The Impact of Tab Alignment and Temperature on Current Density Distribution in a Multi-Tab Lithium-Ion Cell
Authors: Erhard Simon Vincent , Osswald Patrick J , Keil Peter , Wilhelm Joern , Rheinfeld Alexander , Kosch Stephan , Rieger Bernhard , Kloust Hauke , Thoennessen Torge , Jossen Andreas
Published: February 2020

Thermally and electrochemically driven imbalances might reduce the overall net energy within large format lithium-ion batteries. In this study, we designed a proprietary multi-tab pouch cell for investigation of these imbalances depending on cell design and temperature. The cell consists of a single-layered NMC/graphite electrode pair with a length of 50 cm and a width of 10 cm. 22 equidistantly distributed tabs are connected to each electrode giving insight to local potentials within the current collector domain (Fig. 1). Temperature variation is negligible due to the comparably small heat generation of the cell and the global influence of temperature can be analyzed. A high precision measurement setup is prepared for a μV resolution between tab pairs. By that, the internal current density distribution can be assessed.

The cell is operated at 5, 25 and 40 °C and 0.1, 0.5, 1 and 2C current rate, whereby three different tab patterns are applied: Standard pouch cell, counter-tab and center-tab design. It turns out that higher potential drops along the cell as well as larger potential variation occur at elevated temperature. Further, the differentiation of potential difference between the tabs indicates a larger state of charge inhomogeneity at higher temperature, even at low current rates. It might be concluded that the interaction of an increased current collector resistance and an increased electrochemical performance in between the collector foils provokes a more distinct inhomogeneity in current density at higher temperature.

Corresponding to our previous work [1,2], we apply a multi-dimensional modeling approach to the presented multi-tab cell to describe the temperature dependent current spread for purpose of optimized cell design. Based on these simulations, a maximum tab-to-tab distance depending on temperature can be estimated under the objective of an acceptable potential drop along the current collectors.

References:

[1] P.J. Osswald, S.V. Erhard, J. Wilhelm, H.E. Hoster and A. Jossen: Simulation and Measurement of Local Potentials of Modified Commercial Cylindrical Cells - Part I: Cell Preparation and Measurements, Journal of The Electrochemical Society 162 (10), A2099, 2015

[2] S.V. Erhard, P.J. Osswald, J. Wilhelm, A. Rheinfeld, S. Kosch and A. Jossen: Simulation and Measurement of Local Potentials of Modified Commercial Cylindrical Cells - Part II: Multi-Dimensional Modeling and Validation, Journal of The Electrochemical Society 162 (14), A2707, 2015

Figure 1
Hierarchical Molybedenum Sulfide - Carbon Microspheres for High Performance Lithium Ion Battery Anode
Authors: Luo Hongmei , Chen Gen
Published: February 2020

With higher theoretical lithium ion capacity of 670 mAh g–1 comparing with commercial graphite electrodes, molybdenum disulfide (MoS2) may be a promising alternative for lithium ion batteries (LIBs) because it offers unique layered crystal structure with Mo atoms sandwiched between two layers of closely packed S atoms and the MoS2 layers are linked by weak van der Waals interaction. Either bulk or nanoscale MoS2 delivers poor conductivity for the electron/ion transfer, thus leading to obvious capacity loss after several cycles. To overcome these barriers, numerous efforts have been devoted into the engineering of MoS2 nanostructures with optimized electrochemical performances. Herein, we prepared hierarchical MoS2-carbon microspheres via continuous and scalable ultrasonic nebulization route. The structure, composition, electrochemical properties are investigated in detail. The MoS2-carbon microspheres consist of MoS2 nanosheets with a few layers bridged by carbon (15 wt%), which separates the exfoliated MoS2 layers and prevents their aggregation and restacking. The novel architecture offers additional merits such as overall large size, high packing density, which promote their practical applications. The MoS2-carbon microspheres have been demonstrated to deliver excellent electrochemical performances in terms of low resistance, high capacity even at large current density, ultrastable cycling over hundreds of cycles, etc. Specifically, the electrodes exhibited over 900, 800 mAh g–1 at 200, 1600 mA g–1 over 500 cycles, respectively. At higher current density of 3200 mA g–1, a capacity of 730 mAh g–1 can be also maintained. The MoS2-carbon microspheres are practically applicable not only because of the continuous and large scale synthesis via current strategy, but also the robust and integrated architecture which ensures the excellent electrochemical properties.
Microstructural Characterization of Oriented Cathodic Thin Films for Lithium Ion Batteries Prepared By Chemical Solution Deposition
Authors: Ikuhara Yumi H. , Gao Xiang , Sugawara Yoshihiro , Fisher Craig Andrew James , Kuwabara Akihide , Moriwake Hiroki , Kohama Keiichi , Ikuhara Yuichi
Published: February 2020

Rechargeable Li-ion secondary batteries are being developed for use in high power applications, such as fully electric vehicles and hybrid electric vehicles, because of their high energy density and high power density compared to other battery technologies. Future application of multilayer lithium ion secondary batteries requires a thorough understanding of the influence of microstructure on battery performance. In particular, cathode-substrate and cathode-electrolyte interfaces are known to affect charge/discharge rates, cyclability and battery lifetime. In this study, oriented LiMn2O4 and LiCoPO4 cathodic thin films were successfully fabricated on Au/Al2O3 substrates from precursor solutions. The films were analyzed by X-ray diffraction and Cs-corrected scanning transmission electron microscopy (STEM) using high-angle annular dark-field (HAADF) and annular bright-field (ABF) detectors. It was found that the film/substrate lattice misfit affects the degree of epitaxy of the thin films. Direct observation of atom columns showed that epitaxial LiMn2O4 film forms an atomically flat and coherent heterointerface with the substrate, but that the crystal lattice is distorted with a compositional gradient in the film near the interface. Using ABF-STEM, Li-ion columns in the LiCoPO4 cathode film could be viewed directly and antisite defects were identified in the surface regions.

References

[1]Y. H. Ikuhara, et al., J. Phys. Chem. C, 118 (2014) 19540.

[2]X. Gao, et al., Adv. Mater. Interfaces, 1(2014) 1400143.

Figure 1
Lithiated and Sulfonated Poly (Ether Ether Ketone) Binders with High Rate Capability for LiFePO4 Cathodes
Authors: Chiu Kuo-Feng , Leu Hoang-Jyh , Su Shih-Hsuan , Wu Chien-Hsun
Published: February 2020

Sulphonated poly (ether ether ketone) (SPEEK) was synthesized and used as ionic conducting binder for LiFePO4 cathodes. In order to further increase its ionic conductivity, SPEEK was lithiated by adding various amounts of LiClO4 (Li-SPEEK). SPEEK, Li-SPEEK and conventional polyvinylidene fluoride (PVDF) binders were applied to fabricate LiFePO4 cathodes for comparison. The LiFePO4 cathodes using Li-SPEEK with optimized amount of lithiation exhibited higher discharge capacity of 108 mAh/g under high discharge rate (10 C), compared with the LiFePO4 cathode with PVDF binder (80 mAh/g). It can be attributed to the lower charge transfer resistance resulted from the use of Li-SPEEK binder, which contained Li+ ions and exhibited ionic conductivity. The electrochemical impedance spectra showed more than 50 % of reduction in charge transfer resistance for Li-SPEEK compared with PVDF used samples. In addition, the LiFePO4 cathodes using Li-SPEEK and conventional binders exhibited comparable cycling stability in 100 cycles with capacity retention higher than 93%. It indicates that Li-SPEEK is a good candidate as an alternative binder for high rate applications.
Realization of High Performance Lithium Iron Phosphorus Oxynitride Thin Film Cathodes for Lithium Ion Batteries
Authors: Chiu Kuo-Feng , Su Shih-Hsuan , Leu Hoang-Jyh , Jheng Yuan Ruei
Published: February 2020

Experimental realization of nitrogen doping into LiFePO4 films has been carried out by reactive sputtering on graphite substrates without any carbon additive. LiFePOxNy films were deposited under various N2/Ar flow ratios followed by thermal annealing under Ar/H2 gas mixture. The amounts of nitrogen doping increased with the N2/Ar flow ratios. Enhanced Li-N signals were recorded by Fourier transform infrared spectroscopy, where Nitrogen substitutes for Oxygen at LiO6 octahedral structure in LiFePO4. The binding energy bands of the double and triple coordinated N-P bonds were found and the triple bond became predominant with increased nitrogen doping as characterized by X-ray photoelectron spectroscopy (XPS). With nitrogen doping, Fe2+ remained unchanged, whereas Fe-O defects in FeO8 octahedron increased. Nitrogen doping has effectively elevated the conductivity of the films to the order of 104 S/cm, and also reduced the electrochemical impedance. The charge-discharge tests show that capacity of 140 mAh/g at 0.2 C can be obtained with appropriate nitrogen doping. Even at a current rate of 10 C, the optimized LiFePOxNy film can delivered a capacity of 100 mAh/g. The LiFePOxNy films were charged-discharged for 100 cycles at 1C, and 97 % of capacity retention can be achieved for most films.
High Ni Layered Oxide Cathode Materials - Choice of Future High Energy Density Cells
Authors: Zhou Fu
Published: February 2020

Fu Zhou1, Lixin Wang1, Santo Iaconetti1, Yuehui Yin2, Bo Peng2, Yuan Yuan2 and Derek Johnson1

A123 Systems, 200 West Street, Waltham, MA 02451

Wanxiang A123 System Asia Co., Ltd, No. 118 Jianshe No. 2 Road , Xiaoshan District, Hangzhou 311215, China PRC

Lithium ion batteries have already dominated the portable electronics market and are now penetrating into the electrified vehicle market with at a rapid pace. In order to accelerate the adoption of electrified vehicles, increasing cruise range before recharging is a necessity, requiring ever-increasing energy density from the lithium ion battery systems.

For the delivery of high energy density, new generation of cathode materials are under development. Among all the candidates, high Ni layered oxide provides the best chance of fulfilling all the challenging demands. A123 Systems, LLC is now working hard to integrate the high Ni layered oxide into next generation products capable of delivering ≥ 250 Wh/kg specific energy and ≥ 600 Wh/L energy density with favorable cycle/calendar life and safety performances.

A123 Systems, LLC is well known as a supplier of high power lithium ion batteries using lithium iron phosphate.  This paper reviews A123 strategy to expand its focus to also provide safe, high energy batteries, positioned for the EV market.
Evaluation of V2O5 Coatings Grown By Plasma Enhanced and Thermal Atomic Layer Deposition
Authors: Kazadojev I I , O'Brien S , Modreanu M , Osiceanu P , Somacescu S , Apostolopoulou M , Katsarakis N , Koudoumas E , Vernardou D , Pemble Martyn E , Povey Ian M
Published: February 2020

The atomic layer deposition (ALD) of vanadium pentoxide on fluorine doped tin dioxide coated glass substrates has been examined. Growth was performed by employing Tetrakisdimethylaminovanadium with either water, oxygen or oxygen/argon plasma as the co-reagent. It was observed that only the plasma assisted ALD material was crystalline as grown, with all samples requiring a one hour 400°C to give material that demonstrated well orientated material that exhibited long term stoichiometric stability. The optical properties, morphology, stiochiometry and crystallinity are discussed with respect to the materials' electrochemical performance. More specifically intercalation-deintercalation rates and the charge storage capacities. In addition, the influence of Ag doping is investigated both in terms of electrochemical performance and the physical properties of the resultant materials.
On-Demand Internal Short Circuit Device Reveals Li-Ion Cell Design Vulnerabilities and Enables Verification of Safer, Higher Performing Battery Designs
Authors: Darcy Eric
Published: February 2020

In partnership with the National Renewable Energy Laboratory (NREL), we have invented (U.S. Patent #9,142,829) an on-demand internal short circuit (ISC) device that is activated by raising the cell temperature > 57 degC, rather than > 130 degC required without the device. We have achieved > 90% success rate in driving a 2.4Ah (180 Wh/kg) cell design into thermal runaway with a device designed for an anode active material to cathode current collector short and usign a non-shutdown separator (M. Keyser, ECS Phoenix mtg, Oct 2015). Building on this success, we are now implanting the device in cell designs exceeding 250 Wh/kg to learn their design vulnerabilities and effectiveness of safety features like shutdown separators, cathode coatings, current interrupt devices, positive thermal coefficient switches, center mandrels, cell vents, and crimped headers. We are providing our cells to researchers conducting in-operando tomography on cells during thermal runaway (Finegan et. al, Nature Communications, 7924, 2015) for first time video insight into the response of an 18650 cell to a thermal runaway that is internally induced by an internal short circuit instead of external driven by thermal, mechanical, or electrical abuse. This enables the study of conditions that replicate latent defect induced field failures with the most fidelity.

As the specific energy of commercially available 18650 cell designs exceed 250 Wh/kg, we are presented with additional challenges for integrating them into safe, high performing (> 200 Wh/kg) battery designs for manned spacecraft applications. Specifically, these cell designs are susceptible to side wall rupturing and/or eletrode jellyroll ejection during thermal runaway. Such packs require cell interstitial materials that provide high thermal conductivity and structural structural strength. This leaves very little cell surface area for heating unmodified cells into thermal runaway for battery safety testing. In fact, the only way to acheive single cell thermal runaway in these battery designs is by triggerring cells implanted with the ISC device. These tests give us insight into the impact of battery design parameters life cell-cell spacing, cell electrical isolating wraps, and features that protect the adjacent cells from propagating into thermal runaway. Finally, battery flame arresting materials and vents are crucial to prevent flames and sparks for exiting battery enclosures. Our IMLB submission will be our first public forum disclosure of these results.
Implications of Material Reponse for Battery Safety
Authors: Santhanagopalan Shriram , Cao Lei , Zhang Chao , Pesaran Ahmad
Published: February 2020

There has been a significant amount of effort to make lithium ion batteries safer, resulting in improvements across the board from safer cathode chemistries, alternate candidates for anode materials, electrolytes with wider operating windows, separators with better mechanical and thermal properties, to binders that are less reactive under abuse conditions.  At the cell level, safety improvements include tabs that limit electrical conductivity at high temperatures, alternate pathways to dissipate heat and/or abuse reaction currents and preferential channeling of vent gases.  Test methodologies have improved a great deal over the last few years:  we are able to selectively investigate the effect of SEI additives on abuse response of the cell in situ and obtain tomographic images during thermal runaway.  All these capabilities have enabled our understanding of the interactions among the different cell components during cell abuse scenario considerably.

As reported previously, improvements to individual components are not always adequate to address cell safety.  Given the extent of advancements in characterization techniques and material properties, the next logical step is to understand the influence of material-scale-improvements on the cell level response during short-circuit. However, this step is not straightforward.  There are several chemical/ electrochemical reactions involving multiple components that take place simultaneously.  Material properties such as thermal diffusivity and electrical conductivity change during both nominal operation as well as during the abuse reactions.  In this study, we present a rigorous characterization of the reactivity, as well as material properties with aging of the cell.  We then proceed to use these properties to better explain the temperature distribution within the cell during short-circuit. Implications of changes in material properties for propagation of thermal runaway at the cell level are described based on experimental observations.  The results are used in mathematical models to assess effectiveness of different design options in improving cell-level safety.
Electrospun Gel Electrolytes for Li-Ion Batteries
Authors: Croce Fausto
Published: February 2020

The quest for more efficient and low environmentally impacting energy conversion and storage technologies has become a priority for modern society. In particular, rechargeable, high capacity and high power electric energy storage systems, if developed, would play a central role in accelerating the transition toward an electric transportation economy, which, in turn, would dramatically reduce the risks associated with the burning of fossil fuels. To this purpose, ‘ad hoc’ engineered functional materials that join improved electrochemical properties with scalable preparation process for electrodes and electrolytes are needed. The most promising of such materials are those with nanometric-scale dimensions, including nanoparticles and nanofibers. These materials, having very high surface to volume ratio, show enhanced bulk charge transport and faster electrodic reaction rates. Nowadays, new methods have emerged for manipulation, assembly and characterization of nanostructured materials, particularly regarding functional electrodes and electrolytes based on nanofibers. Among the methods for generating nanofibrous structures, electrospinning is a top-down approach proved to be simple, cost effective and versatile, which allows the fabrication of polymeric and inorganic nanofibers in a scalable process. Electrospinning is based on the application of an electric field to a drop of a viscous solution on the tip of a spinneret. The electric field elongates the drop to form a conical shape known as the Taylor cone. For an electric field critical value, the repulsive electrical forces between the charges in the fluid overcome the surface tension of the drop and a charged jet of the solution is ejected from the tip of the Taylor cone. The jet becomes unstable and rapidly whipping leading to the evaporation of the solvent and the formation of dry, continuous, ultra-thin fibers on the collector [Fig. 1]. The collected electrospun mats present peculiar properties, such as very high surface to volume ratio, low density, high pore volume and remarkable mechanical strength.

            In this presentation, the electrospinning technique will be illustrated particularly regarding the optimization of the system and process parameters, which mostly influence the electrospun nanofibers. The characteristics of some gel electrolytes formed by electrospun polymeric separators based on PVdF and PEO will be discussed.

Figure 1
Carbon Disulfide As a Novel Additive for High-Performance Lithium Sulfur Batteries
Authors: Gu Sui , Jin Jun , Wen Zhaoyin , Qian Rong , Zhuo Shangjun
Published: February 2020

Rechargeable lithium batteries with long cycle life and high energy density have great market demand for energy storage systems. The lithium sulfur battery is attracting intense interest because of its theoretical capacity and energy density, which is much higher than that of Lithium ion battery based on intercalation reactions. Moreover, the cathode, sulfur, is highly abundant, low cost and nontoxic. Lithium sulfur battery has been considered as a next-generation energy storage system, especially for large scale applications.[1] The main obstacle to realize the practical use of lithium sulfur battery lies in the rapid capacity fading, which is primarily attributed to the solubility and shuttle of polysulfides generated during charge and discharge.[2] The shuttle of polysulfides between electrodes not only decreases utilization of sulfur, but also greatly corrodes lithium and reduces coulombic efficiency of the cell.

Here, we introduced carbon disulfide (CS2) as an additive for DOL/DME-based electrolytes. We found that CS2 is able to form complexes with polysulfides. These complexes are soluble in DOL/DME and can suppress shuttle reactions. In addition, the employ of CS2 can also passivate the surface of both cathodes and anodes. Improved coulombic efficiency and cycling performance were exhibited in Fig 1.a combined with LiNO3[3] as binary additives. Fig 1.b presents the morphology of anode after 50 cycles. It's observed that the surface is quite dense and smooth. XPS (Fig 1.c) shows the existence of LiF. This result indicates the ability of CS2 to passivate the Li metal because of the halides, which can improve Li cycling.[4]   

Fig 1. a. Electrochemical performance of lithium sulfur batteries. b. Morphology of Li anode after 50 cycles with CS2 and LiNO3 additives. c. The F 1s XPS spectra of Li anode after 50 cycles with CS2 and LiNO3 additives.

References

[1] X.L. Ji, L.F. Nazar, Journal of Materials Chemistry, 20 (2010) 9821-9826.

[2] Y.V. Mikhaylik, J.R. Akridge, J. Electrochem. Soc., 151 (2004) A1969.

[3] D. Aurbach, E. Pollak, R. Elazari, G. Salitra, C.S. Kelley, J. Affinito, J. Electrochem. Soc., 156 (2009) A694.

[4] Y.Y. Lu, Z.Y. Tu, L.A. Archer, Nature Materials, 13 (2014) 961-969.

Figure 1
Lithium Complex Hydride Solid-State Electrolytes with Conventional Liquid Electrolyte-like Conductivity
Authors: Kühnel Ruben-Simon , Yan Yigang , Remhof Arndt , Rentsch Daniel , Lodziana Zbigniew , Battaglia Corsin
Published: February 2020

Solid-state electrolytes have the potential to improve the safety properties of lithium-ion batteries. Many different materials have been proposed over the years. However, especially at lower temperatures (at or near room temperature), most solid-state electrolytes display lithium ion conductivities lower than the one of conventional organic liquid electrolytes (about 3-5 mS cm-1 at room temperature). Several sulfides are among the only compounds reported so far displaying lithium ion conductivities in or above this range. However, issues regarding costs and/or electrochemical stability of sulfide electrolytes still remain.

Here we report on several complex hydrides that display, for the first time, lithium ion conductivities near room temperature comparable to liquid organic electrolytes, adding a second class of materials to the group of highly conductive solid-state electrolytes and paving the way for high-power lithium solid-state batteries. An in depth study was carried out to understand the lithium transport mechanism of these materials. Density functional theory calculations combined with molecular dynamics simulations support a new anion assisted lithium hopping mechanism. We also show excellent stability of our solid-state electrolytes via long-term cycling in half-cell battery configuration.

Figure 1
Electrolyte Studies for High Voltage Lithium Ion Batteries
Authors: Delp Samuel A. , Allen Joshua L. , Jow T. Richard
Published: February 2020

Extensive research on next generation lithium ion batteries, specifically batteries operating at high voltage (>4.4V), is currently underway. There are several issues that need to be addressed in order to produce a viable product. For example, graphite anodes are used in current state of the art batteries but silicon-based anodes offer higher energy density. Also, cathode materials that are electrochemically active at high voltages are available, e.g. LiNi0.5Mn1.5O4 (LNMO) @ 4.7V and LiCoPO4 (LCP) @ 4.8V. Unfortunately, batteries composed of these materials with the state of the art electrolyte suffer from poor cycle life. New electrolytes are essential for the operation of next generation high voltage lithium ion batteries.

This research focused on the electrolyte for LNMO-graphite based batteries. The importance of not only the high voltage stability of the electrolyte but also the low voltage stability will be discussed. Cyclic voltammetry (CV) on glassy carbon electrodes allow for the investigation of both the oxidative and reductive stability of the electrolytes. Cycle life data, Coulombic efficiency, and fade rate data was collected from LNMO-graphite coin cells. Differential capacity (dQ/dV) vs. V plots were also constructed from the coin cell data to show how the electrochemical behavior changed over time. The dQ/dV vs V data for the state of the art electrolyte show a buildup of impedance over time which was also evidenced via electrochemical impedance spectroscopy (EIS). Several different lithium salts and additives were investigated in this study. The results suggest that while the oxidative stability of the electrolyte is important, the reductive stability must not be ignored.
Reaction Mechanism of Alluaudite Sodium Iron Sulphate As High Energy Density Cathode Material for Na-Ion Battery
Authors: Nishimura Shinichi , Oyama Gosuke , Yamada Atsuo
Published: February 2020

The sodium-ion battery system is now growing as a potential alternative to the lithium-ion battery for large energy storage systems. The ubiquitous element Na allows us to realize stable production of large scale storages for broader applications. Electrode materials for the Na system is under intensive development by many battery researchers to make properties of the Na-ion battery comparable to those of Li-ion battery. In such pursuit we developed an ideal cathode material with abundant constituents sodium, iron and sulfate ions.1 Alluaidite-type sodium iron sulfate Na2+2x
Fe2–x
(SO4)3 exhibits high energy density due to high working potential of 3.8 V vs. Na/Na+. Large tunnel structure in the alluaudite framework derives high Na-ion conductivity. Thus Na2+2x
Fe2–x
(SO4)3 electrode allows high-rate battery operation.In this poster, we present detailed reaction mechanisms of Na2+2x
Fe2–x
(SO4)3 for Na batteries by means of crystal structural characterizations.

  As mentioned in our first report of this system, Na2+2x
Fe2–x
(SO4)3 (NFS) electrode undergoes irreversible change during first charing of NFS/Na half cells. Subsequent discharging and charging cycles are reversible. We carried out ex situ structural analysis to understand about the irreversible and reversible changes during electrochemical reaction.

  Crystal structure of NFS powder (x ~ 0.28) was successfully analyzed by the alluaudite structure model with C2/c symmetry.2 Ex situ structural analysis of NFS electrodes were carried out by powder X-ray diffraction using synchrotron radiation at Photon Factory in KEK, Japan. Electrochemically reacted samples were also successfully analyzed by using a monoclinic lattice with C2/c symmetry, which is isomorphic with the pristine lattice. Volume change is less than 5% in whole reaction range. The refined structure shows that the desodiation/resodiation reactions are essentially topochemical, while partially irreversible cation rearrangement is observed. One of the Na sites, Na3, is preferentially extracted due to higher site-potential than the other two sites. This model is consistent with computational evaluation of relative defect formation energy at the Na sites.1 Subsequent extraction sequence shows complex behaviors involving Fe migrations. 

[1] P. Barpanda, G. Oyama, S. Nishimura, S.-C. Chung, and A. Yamada, Nat. Commun., 5:4358, 2014.

[2] G. Oyama, S. Nishimura, Y. Suzuki, M. Okubo, and A. Yamada. ChemElectroChem, 2(7):1019–1023, 2015.

[3] G. Oyama, O. Pecher, K. J. Griffith, S. Nishimura, R. Pigliapochi, C. P. Grey and A. Yamada, in preparation.

Figure 1