bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on LiMn1.5Ni0.4Cr0.1O4 Cathode Spinel Combined with Graphene for Lithium Ion Batteries
Authors: Katiyar Rajesh K. , Shojan Jifi , Puli Venkata S , Sahoo Satyaprakash , Morell Gerardo , Weiner Brad R. , Katiyar Ram S.
Published: February 2020

The low-cost development of rechargeable lithium ion batteries is of considerable technological importance.  In this context, the use of active cathode LiMn1.5Ni0.4Cr0.1O4 material has attracted much attention due to its stable structure while intercalation and de-intercalation of lithium ions. The necessity of such battery material is that the energy density stored electrochemically in the electrodes is quite high. They combine high theoretical energy storage capability with low weight and good mechanical strength. Here we report the development of a rechargeable lithium ion battery with homogeneous mixing of graphene powder (with 10, 15 and 20%) in active cathode materials for high energy applications. The reduced graphene oxide was synthesized using modified Hummers method with high purity concentrated of H2SO4 (50 ml), oriented pyrolytic graphite, KMnO4 (7 g) and H2O2 (30 wt %). The resultant mixture was stirred well and then filtered with the help of a glass filter. The obtained precipitates were dried for 30 h in a vacuum oven at room temperature. Highly conducting reduced graphene powder was obtained using hydrazine treatment. The redox behavior of the cell, which is normally too slow for practical applications, is accelerated with highly conductive powder of the graphene (which itself functions as an active cathode material). Intimate mixing of the two materials is achieved by a slurry maker using an organic solution for a cathode paste. The resulting electrode can be repeatedly charged to near its theoretical limit and discharged. The gravimetric energy density of our composite cathode materials exceeds that of the LiMn1.5Ni0.4Cr0.1O4 oxide electrodes in lithium-ion batteries, a feature that is likely to prove advantageous in applications where weight, rather than volume, is a critical factor. The aforementioned results will be discussed.
Examining the Electrochemical Impedance at Low States of Charge in Lithium- and Manganese-Rich Layered Transition-Metal Oxide Electrodes
Authors: Gallagher Kevin G. , Gowda Sanketh R. , Jansen Andrew N. , Dees Dennis W.
Published: February 2020

Lithium- and manganese-rich layered transition-metal oxide (LMR-NMC) intercalation electrodes are projected to enable batteries with high energy density and low costs for energy. However, implementation of LMR-NMC materials are challenged by life limiting mechanisms as well as less than desired rate performance. Here-in, we use electrochemical characterization of LMR-NMC electrodes to examine the large magnitude of impedance and the asymmetric polarization between charge and discharge at low states of charge (SOC).

The lithium metal oxide cathode materials examined were LMR-NMC and standard NMC both from Toda Kogyo (Japan). The LMR-NMC material, referred to as HE5050, had the composition 0.5Li2MnO3•0.5LiMn0.375Ni0.375Co0.25O2 (or in layered notation Li1.2Ni0.15Mn0.55Co0.10O2). The NMC material had composition of Li1+x(Ni1/3Mn1/3Co1/3)1-xO2 and can be considered to be the commercial standard stoichiometry for Li-ion transportation cells at the time of this publication. Full cells used A12 graphite (Conoco Phillips) and half cells used lithium metal (FMC Lithium) both with standard LiPF6based carbonate electrolyte. A three electrode pouch cell was utilized for the asymmetry polarization experiments in the study, with a composite LMR-NMC electrode as the working electrode, lithium metal was used as the reference and counter electrodes

The area-specific impedance (ASI) of LMR-NMC in Fig. 1 displays a similar dependency as standard layered lithium metal oxides when compared as a function of voltage rather than SOC. The increasing and asymmetric behavior of the polarization in LMR-NMC measured at low SOC is hypothesized to be the result of the differing lithium contents and lithium mobilities in the heterogeneous, nano-composite metal oxide material. Transport of lithium within LMR-NMC is suggested to be governed by the relatively facile nickel- and cobalt-rich domains even as this domain appears to reach full lithiation. As the majority of capacity at low SOC in LMR-NMC is associated with the lithium- and manganese-rich domains, the observed high impedance presents a significant hurdle to utilizing this capacity in moderate power-to-energy ratio applications. Much work is needed to clarify the transport and structural mechanism in LMR-NMC. Other studies have shown the structural transformation known as voltage fade is less severe with lower lithium content. However, lowering the lithium stoichiometry also tends to lower the specific energy of the material at beginning of life. Optimizing the stoichiometry of the lithium and manganese to achieve a maximum specific energy over life at relevant discharge rates is a potentially viable path forward.

Figure 1
On the Stability and Reactivity of Phenothiazine-Based Redox Shuttles for Overcharge Protection
Authors: Odom Susan A , Risko Chad , Casselman Matthew D , Elliott Corrine F , Narayana Kishore Anand , Kaur Aman Preet
Published: February 2020

The performance of aromatic compounds as redox shuttles for overcharge protection in lithium-ion batteries is variable and difficult to predict. Redox shuttles can decompose in battery electrolyte in their neutral and oxidized forms, both of which are present during overcharge protection. The reasons for differing stability in compounds with only slight structural differences is often unclear, and the exploration of decomposition of redox shuttles has been severely limited, restricting our ability to design improved versions of redox shuttles. To better understand the stability and reactivity of redox shuttles (also relevant to the improvement of positive electrode materials in non-aqueous redox flow batteries) our research has focused on measuring the stability of neutral and oxidized forms of redox shuttle candidates as well as using a variety of spectroscopic methods to analyze the byproducts of decomposition, both from radical cations generated in model solvents and electrolytes from postmortem analysis of failed batteries.

Figure 1
High-Performance Non-Aqueous Redox Flow Batteries at Pnnl
Authors: Wei Xiaoliang , Xu Wu , Cosimbescu Lelia , Vijayakumar Murugesan , Liu Tianbiao , Liu Jun , Wang Wei , Sprenkle Vincent
Published: February 2020

With the potential applications in power grid stabilization, redox flow battery has been widely considered as a promising large- and middle-scale stationary energy storage technology. The cell architecture enables separation of the energy capacity and power rating, offering excellent scalability and tremendous design flexibility to meeting different energy-to-power ratio requirements. Traditional aqueous flow batteries have been extensively developed, but the limited voltage window narrows down the intrinsic capacity to achieve high energy density. Therefore, alternative nonaqueous redox flow techniques are rapidly emerging because of their wider voltage window that has a direct impact on the energy density. Currently, the primary focus of the nonaqueous flow research is on the flow chemistry study. Most of these efforts use organic electroactive materials taking advantage of the structural diversity and tunability.1

Here we update the flow battery community with our recent development in nonaqueous flow chemistries. The first type is the hybrid lithium-organic flow battery, which uses Li-based anode and organic catholyte materials including ferrocene and TEMPO.2,3 High solubilities in the supporting carbonate electrolytes were obtained to TEMPO (2M) and structurally modified ferrocene (0.8M). Taking advantage of the low potential of the Li anode, cell voltages of ~3.5V were achieved. Consequently, these flow cells delivered high volumetric energy densities of 50Wh/L for ferrocene and 126Wh/L for TEMPO, respectively.

Because of the limitations of the Li anode, organic anolyte materials were explored coupled with another organic catholyte material in the second type. Cell voltages of >2V were obtained in these total-organic flow batteries. Electrolyte optimization was performed to achieve improved cycling stability and gain mechanistic understandings of capacity fading. The flow cell tests demonstrated remarkable cell efficiencies and high operational current densities that exceed those of most reported non-aqueous flow chemistries.

References

                (1)           Wang, W.; Luo, Q. T.; Li, B.; Wei, X. L.; Li, L. Y.; Yang, Z. G. Advanced Functional Materials
2013, 23, 970.

                (2)           Wei, X.; Cosimbescu, L.; Xu, W.; Hu, J. Z.; Vijayakumar, M.; Feng, J.; Hu, M. Y.; Deng, X.; Xiao, J.; Liu, J.; Sprenkle, V.; Wang, W. Adv Energy Mater
2014.

                (3)           Wei, X.; Xu, W.; Vijayakumar, M.; Cosimbescu, L.; Tianbiao, L.; Sprenkle, V.; Wang, W. Adv Mater
2014.

Figure 1
Liquid Catholyte Molecules for Non-Aqueous Redox Flow Batteries
Authors: Zhang Lu , Huang Jinhua , Cheng Lei , Assary Rajeev , Wang Peiqi , Xue Zheng , Burrell Anthony K. , Curtiss Larry
Published: February 2020

Non-aquoes redox flow battery is a unique energy storage technology. Unlike traditional battery systems, the active energy storage material is in mobile phase and could basically be stored anywhere separately. This gives a lot of flexibility in terms of capacity, power and safety control, making it an idea candidate for large scale stationary energy storage application.

Material development for this technology is crucial for possible implementation. Molecular engineer of organic redox active molecules could lead to tunable physical and electrochemical properties, including solubility in organic solvents, molecular mobility, redox potential, and electrochemical reversibility, which are key factors to energy storage applications. A novel series of catholyte molecules, ANL-8, ANL-9, and ANL-10, has been developed by incorporation of PEO chains with different lengths on one or both sides of the dimethoxy-di-tert-butyl-benzene based redox structure. All of these molecules can afford electrochemically reversible behavior with similar redox potentials around 4.0 V vs Li/Li+. Due to the asymmetrical incorporation of PEO groups, ANL-8 and ANL-9 are found to be liquid at room temperature. The results from the diffusion, viscosity, DFT calculation, overcharge evaluation, and cell cycling indicate that ANL-8 is likely to be the best candidate among the redox active molecules in this study and does have promise to be a novel catholyte material for NRFBs. To our knowledge, it is the first time that the liquid catholyte molecules have been discovered for the application of NRFBs. The liquid nature of these catholyte molecules may open a new door to utilization of these molecules as the solo or co- solvents for high energy NRFB applications.
Solution Phase Catalysts for Lithium-Oxygen Batteries
Authors: Shen Yue , Huang Yunhui , Sun Dan
Published: February 2020

A lithium-oxygen battery (LOB) would deliver the highest energy density of a rechargeable battery. But there is a central problem of catalytic action required for the rechargeable LOB: conventional solid state catalysts are not effective enough to catalyze the multiphase electrochemical reactions on the cathode side. The discharge product Li2O2 is also in solid state; it will accumulate at the catalyst surface and hence block the electrode reactions during the discharge process. Meanwhile, during the charging process, it is also difficult to make good contact between the solid catalyst and Li2O2. Therefore, instead of solid catalysts, some novel solution phase catalysts have been developed to solve the above problems1-3.

Here, we present a solution-phase catalyst, iron phthalocyanine (FePc), and provide a mechanism involving iron-oxygen coordination and a redox shuttle across the electrolyte4. The Fe-oxygen coordination and the electron dislocation in the big conjugated structure lowers the energy of the high energy intermediates in the ORR and OER. The dissolved FePc can act as a molecular shuttle of (O2)− species and electrons between the surface of electronically conducting carbon and product Li2O2 particles. With this novel approach, the formation and decomposition of Li2O2 is no longer confined to the carbon surface. The Li2O2blocking effect in the discharge process was greatly depressed. Meanwhile, the redox shuttle mechanism effectively lowers the overpotential during the charging process. Thus, the capacity and cyclability of the battery was improved dramatically.

Some other solution phase catalysts based on the redox shuttle mechanism, such as ferrocene-derived compounds and iodine, will also be discussed. The efficiency of various redox couples to oxidize the Li2O2during charging is compared with an oxygen monitoring method. We also show some evidence of side reactions caused by some certain redox shuttle compounds.

 Reference:

(1)           Y.H. Chen, S.A. Freunberger, Z.Q. Peng, O. Fontaine & P.G. Bruce, "Charging a Li-O-2 battery using a redox mediator". Nat. Chem., 2013, 5(6),489-494.

(2)           H.-D. Lim, H. Song, J. Kim, H. Gwon, Y. Bae, K.-Y. Park, J. Hong, H. Kim, T. Kim, Y.H. Kim, X. Lepró, R. Ovalle-Robles, R.H. Baughman & K. Kang, "Superior Rechargeability and Efficiency of Lithium–Oxygen Batteries: Hierarchical Air Electrode Architecture Combined with a Soluble Catalyst". Angewandte Chemie International Edition, 2014, 53(15),3926-3931.

(3)           B.J. Bergner, A. Schurmann, K. Peppler, A. Garsuch & J. Janek, "TEMPO: A Mobile Catalyst for Rechargeable Li-O2 Batteries". J. Am. Chem. Soc., 2014, 136(42),15054-15064.

(4)           D. Sun, Y. Shen, W. Zhang, L. Yu, Z. Yi, W. Yin, D. Wang, Y. Huang, J. Wang, D. Wang & J.B. Goodenough, "A Solution-Phase Bifunctional Catalyst for Lithium–Oxygen Batteries". J. Am. Chem. Soc., 2014, 136(25),8941-8946.
Flower-like Nickel Sulfide As Efficient Electrocatalyst for Lithium Air Batteries
Authors: Ma Zhong , Yuan Xianxia , Li Lin , Ma Zi-Feng
Published: February 2020

Lithium air batteries (Li-air batteries) can realize the reversible transport between chemical and electric energy by electrochemical reactions of lithium at the anode and air (O2) at the cathode, respectively1-3 and have ultrahigh theoretical specific energy (11140 Wh∙kg-1 excluding oxygen and 3505 Wh∙kg-1 if oxygen included)3
,
4. Therefore, they have attracted the widespread concern of electric vehicle industry and the relevant researchers.

However, Li-air technology is still remained at an early stage of development at this moment. Many problems, such as low specific energy, low round-trip efficiency, poor cycling life and rate capability hinder the practical applications of Li-air battery technology5
,
6. An efficient and stable cathode catalyst is one of most promising strategies to improve the performance of Li-air batteries7
,
8.

In this work, a novel flower-like nickel sulfide was synthesized via hydrothermal method and used as the efficient electrocatalysts for cathode of Li-air batteries. The flower-like NiS is a promising candidate as an efficient electrocatalyst for non-aqueousrechargeable Li-air batteries due to its good performance.

Acknowledgements

The authors are grateful for the financial support of this work by the National Science Foundation of China (21176155 and 21476138).

References

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

2.      G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson and W. Wilcke, J. Phys. Chem. Lett., 1, 2193 (2010).

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

4.      M. Armand and J. M. Tarascon, Nature, 451, 652 (2008).

5.      A. C. Luntz and B. D. McCloskey, Chem. Rev. (2014), DOI: 10.1021/cr500054y.

6.      J. Christensen, P. Albertus, R. S. Sanchez-Carrera, T. Lohmann, B. Kozinsky, R. Liedtke, J. Ahmed and A. Kojic, J. Electrochem. Soc., 159, R1 (2012).

7.      Z. Ma, X. Yuan, L. Li and Z.-F. Ma, Chem. Commun., 50, 14855 (2014).

8.      H. S. Jadhav, R. S. Kalubarme, J.-W. Roh, K.-N. Jung, K.-H. Shin, C.-N. Park and C.-J. Park, J. Electrochem. Soc., 161, A2188 (2014).
Analysis of the Aqueous/Solid Interface in a Mixed Aprotic/Aqueous Lithium-Air Battery
Authors: Uhlmann Christian , Braun Philipp , Illig Jörg , Ivers-Tiffée Ellen
Published: February 2020

A rechargeable Li-air cell is promising due to its high theoretical energy density of about 11140 Wh/kg. A practical energy density of approximately 1000 Wh/kg [1] would be still about five times higher compared to a state-of-the-art Li-ion cell.

However, there are manifold problems concerning cell chemistry, reaction kinetics and cycleability of Li-air cells. In this study, a mixed aprotic/aqueous Li-air cell with a Li3xLa2/3-xTiO3 (LLTO) solid electrolyte was characterized in a new interface-cell setup. This setup is capable to analyse the polarization contribution caused by the liquid/solid interface between the solid electrolyte and different liquid electrolytes.

The cell design is inspired by Abe et al. [2], consisting of two compartments, which are in contact with the solid electrolyte. Four-point electrochemical impedance measurements are performed using two electrodes on both sides. The excitation signal is applied on the outer working electrodes (WE, CE) and the voltage is measured between the inner reference electrodes (RE1, RE2). The impedance spectra are further processed by calculating their distribution of relaxation times, to clearly separate the different processes [3].

The special cell design allows a selective investigation of a single liquid/solid interface process by assembling different symmetric cells, using the same liquid electrolyte in each compartment. By changing the ratio of conducting salt to solvent (Fig. 1), we clearly defined the interface process in a frequency range from 102 Hz to 103 Hz and determined an activation energy of 0,44 eV. Furthermore, the interface process is a major contribution to the overall polarization, which even exceeds the contribution of bulk electrolyte and grain boundary for low lithium concentration and low pH-value.

References: 

[1] Jake Christensen et al., Journal of The Electrochemical Society, 159 (2) R1-R30 (2012)                  

[2] Takeshi Abe et al., Journal of The Electrochemical Society, 152 (11) A2151-A2154 (2005)                    

[3] Helge Schichlein et al., Journal of Applied Electrochemistry, 32 (8) 875-882 (2002)

Figure 1
TiO2 Nanotubes/Ionic Liquid Electrolyte System Enhances Li-Ion Battery Performance
Authors: Chu Peter Pojen , Tuan Jhen-Bin
Published: February 2020

High capacity advanced lithium ion batteries (LIBs) utilizes non-volatile ionic liquid (IL) electrolyte is considered a  promising candidate to address the safety and durability issues of traditional LIBs. Compared to organic-based electrolyte, however, IL has lower ionic conductivity at almost temperature range and shows less effective contact with the electrodes in absence of organic solvent, thus created barrier of lithium transfer at the electrolyte-electrode interface, which in turn reduce the cell performance
1
. Current study is focused on the design of composite ionic liquid electrolyte which gives higher ionic conductivity coupled with the improved of interface stability. Highly conductive electrolyte could be achieved through optimizing synergistic function between ionic liquids, salt, and the PVdF substrate. By suitable composition of lithium-bis-(trifluoromethyl sulfonyl)imide (Li-TFSI) and 1-butyl-3-methyl imidazolium bis-(trifluoromethyl sulfonyl)imide (BMI-TFSI) ionic liquids in poly-(vyniliden fluoride-hexafluoropropylene) (PVDF-HFP) co-polymeric host material,  optimized membrane morphology is achieved through phase inversion technique during membrane casting, where an unique pore structure is formed.  High ionic conductivity in the order of 10-3 Scm-2 is observed in PVDF-HFP: BMI-TFSI: Li-TFSI (10:10:2, w/w) electrolyte system, which is found to be higher than that of commercial membrane with liquid electrolyte. . Furthermore, the addition of small amount of TiO2 nanotubes (TiNT) incorporated onto the ionic liquid electrolyte system further raises the ionic conductivity up to ~1.5 x 10-3 Scm-2 (25 oC) and ~8.0 x 10-3 Scm-2 (80 oC), which is attributed both to higher lithium salt dissociation in presence of TiO2 and the establishment of more direct ion conducting pathway
2
. Further addition of TiNT, however, leads to reduction of ionic conductivity, which drops significantly after 5 wt% (relative to the solvent) of TiNT addition, which is probably the result of inorganic self-aggregation. Wider thermal decomposition around ~400 oC from TGA and DSC shows a remarkable improvement in thermal stability of membrane containing TiNT. Battery performance in a Li/electrolyte-TiNT/LiFePO4 coin cells indicates relatively high discharge specific capacity around ~136 mAh/g at 0.05 C moderate electrochemical cycling and shows better cycling performance with almost constant ~ 99% coulombic efficiency as a result of improved electrolyte interface stability to the electrode.

References:

Y. Kobayashi, Y. Mita, S. Seki, Y. Ohno, H. Miyashiro and N. Terada, J. Electrochem. Soc., 2007, 7, 677-681

H.K. Liu, G. X. Wang, Z. P. Guo, J. Z. Wang, and K. Konstantinov, J. New Mat. Electrochem. Systems, 2007, 10, 101-104
Specific Capacity and Capacity Fading of Interstitial and Substitutional Doping of Li in LiNi0.3Co0.3Mn0.3Ti0.1O2
cathode Material for High Energy Density Li-Ion
Authors: Rusdi Roshidah , Kamarulzaman Norlida , Elong Kelimah , Abd Rahman Azilah
Published: February 2020

Pure and single phase LiNi0.3Co0.3Mn0.3Ti0.1O2 , Li1.05Ni0.3Co0.3Mn0.3Ti0.1O2 and Li1.05Ni0.3Co0.
25Mn0.3Ti0.1O2 materials were successfully prepared using a self-propagating combustion method. The structure and morphology of the materials were characterized using X-Ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and the elemental analysis were done using by Energy Dispersive X-Ray Spectroscopy (EDX). The oxidation state of element and their chemical environments were identified using X-Ray photoelectron Spectroscopy (XPS). The electrochemical performances of the materials were carried by means of galvanostatic charge-discharge test on the fabricated cells.  XRD results showed that the materials are impurity-free and single phase with well ordered hexagonal layered structure of R-3m space group. The different samples annealed at 700 °C for 48h showed variations in discharge capacities. The discharge capacities are between 130 and 141 mAhg-1. The undoped LiNi0.3Co0.3Mn0.3Ti0.1O2 compound exhibits the highest first cycle capacity of 141.3 mAhg-1 over the voltage range of 2.5 to 4.2 V and the lowest capacity was 130.43 mAhg-1 for sample Li1.05Ni0.3Co0.
25Mn0.3Ti0.1O2. The 30th cycle revealed that the Li interstitially doped material is (Li1.05Ni0.3Co0.3Mn0.3Ti0.1O2) shows the highest specific discharge capacity of 131.74 mAhg-1. The capacity fading is only about 1.3% compared to 7.66% for undoped LiNi0.3Co0.3Mn0.3Ti0.1O2
and 12.3% for Li substitutionally doped material (Li1.05Ni0.3Co0.
25Mn0.3Ti0.1O2). The XPS studies showed that the binding energy of Li 1s is lowest for the best performance compound meaning that the Li+ ions can be extracted more easily from Li1.05Ni0.3Co0.3Mn0.3Ti0.1O2 than the other two materials. Therefore, XPS results show that the deintercalation of Li from the interstitially doped compound was much more efficient and enhanced the electrochemical performance of the material. The results also suggest that the self-propagating combustion method is a good synthesis method for the preparation of LiMn0.3Co0.3Ni0.3Ti0.1O2 and their Li doped materials for applications in lithium-ion batteries.
Electrochemical Performance of Full Concentration Gradient Cathode for Lithium-Ion Batteries
Authors: Wu Huiming , Xu Rui , Lu Jun , Amine Khalil
Published: February 2020

Worldwide effort is being devoted to development of lithium-ion batteries for consumer devices, plug-in hybrid electric vehicles (PHEVs) and all-electric vehicles (EV), which require higher energy, increased safety, and lower cost. Most commercial lithium-ion batteries use a layered LiCoO2 as the cathode material, but LiCoO2has a limited practical capacity of about 140 mAh/g. A high capacity cathode material with high packing density is thus being sought to improve the energy density of lithium-ion batteries with improved safety.

Recently, some novel design structures cathode material are reported, such as core-shell, gradient material. First, a co-precipitation process is used to synthesize core-shell or gradient structure spherical precursor, then using this precursor to prepare a same structure cathode material. Using this new process, it is easy to control the elements distribution inside of single particles. This concept make it is possible to achieve the high capacity, cycling life and safety for a cathode material. So the composition design is based on those, high Ni in bulk material for high capacity and high Mn on the surface for safety with certain Co are investigated.

In this study, we investigated a full concentration gradient material, and the average composition is closed to Li1.0Ni0.6Co0.2Mn0.2O2. The material was synthesized by a solid-state reaction from full concentration gradient spherical precursor Ni0.6Co0.2Mn0.2(OH)2 and LiOH precursors. The full concentration gradient spherical precursor Ni0.6Co0.2Mn0.2(OH)2was prepared by a co-precipitation process. It exhibited uniform spherical particle shape with 15-mm diameter and high tap density of 2.7 g/cc. The electrochemical performance of the material was evaluated in a coin-cell. When the current density was 16 mA/g (C/10), the discharge capacities were about 191 mAh/g.

The significant improvement in tap density and the high capacity of this material makes it a potential cathode material for high energy battery application.

Acknowledgments

The authors acknowledge the financial support of the U.S. Department of Energy, FreedomCAR & Vehicle Technologies Office, under Contract No. DE-AC02-06CH11357.

Figure 1
Understanding Complex Ion Dynamics in Lithium-Ion Battery Electrolytes from First Principles
Authors: Ong Mitchell T. , Lordi Vincenzo , Bremer Timo , Gyulassy Attila , Draeger Erik W. , Bhatia Harsh , Pask John E.
Published: February 2020

Lithium-ion secondary batteries are commonly used to power many consumer devices such as handheld phones, laptops, portable music players, and even electric vehicles. One of the key properties that influence the performance of lithium-ion batteries is the ionic conductivity of the electrolyte. This is dependent on the mobility of the Li ion in solution and also related to their solvation structure. In this work, we have performed first principle molecular dynamics of an LiPF6 salt solvated in different organic solvents such as ethylene carbonate (EC), ethyl methyl carbonate (EMC) and a mixture of the two. We observed that the diffusivity of Li+ is correlated to the degree of Li+ solvation. Corresponding analysis for PF6
- shows greater diffusivity than Li+ associated with a weakly-bound, poorly defined first solvation shell. Using a recent analysis method to study the distribution of directional change from relative angles at successive time intervals, we also characterize the complex motion of these ions and find distinct patterns for each ion in different organic solvents. These results provide valuable insight that can be used to improve the cycling rate of Li-ion batteries and potentially lead to the design of new electrolytes for better overall battery performance.
A New Type of Reference Electrode for Three-Electrode Setups: Choice of Material and Geometry
Authors: Costard Janina , Ender Moses , Illig Jörg , Weiss Michael , Ivers-Tiffée Ellen
Published: February 2020

Electrochemical Impedance Spectroscopy (EIS) is highly supportive for analyzing electrode processes in lithium-ion cells. Commonly, a three-electrode setup is used, with a lithium metal counter electrode and/or a lithium metal point-like reference electrode. But its usability is restricted, as lithium metal as a counter electrode often dominates the impedance response, and in general, causes a stochastic component in the EIS data. Furthermore, a point-like lithium metal reference electrode may cause errors such as quantitative factors, cross contaminations and inductive artifacts, as shown by experiment and FEM-simulation [1]. Therefore, material choice and geometric arrangement of a reference electrode seems crucial for obtaining reliable, reproducible and long-term stable measurements.

Li4Ti5O12 (LTO) was already proposed in literature as a most promising candidate, showing a stable potential plateau at 1.55 V versus lithium, because of a two-phase equilibrium [2]. This study compares LTO versus lithium metal and examines various geometries for reference electrodes by EIS measurements and FEM-simulations.

Our results recommend a reference electrode in a mesh-type design, centered between two separators, as most reliable in terms of symmetry. Furthermore, an aluminum mesh slurry coated by fine LTO particles delivered a stable potential over more than hundred hours, as proven by potential measurements.

Finally, the suitability of this new type of reference electrode is validated for electrochemical impedance spectroscopy and C-rate tests.

References

[1]        M. Ender, A. Weber, E. Ivers-Tiffée, Journal of the Electrochemical Society, 159 (2012), A128-A136

[2]        F. La Mantia, C.D. Wessells, H.D. Deshazer, Y. Cui, Electrochemistry Communication, 31 (2013), 141-144
Thermofluids Analysis of the Coolant Flow during Lithium-Ion Battery Operation
Authors: Serincan Mustafa Fazil , Tabatabaei Malazi Mahdi
Published: February 2020

Thermal management of lithium ion battery packs has been accepted as one of the most critical application considerations amid the bad publicity suffered from the battery fires in the electric vehicles and airliners. Removal of the heat generated during lithium battery operation at high charge and discharge rates and rapid load changes is at paramount importance to restrain temperature rises. Forced air-cooling and liquid cooling via channels between cell pairs are frequently used in the designs of battery packs used in commercial applications.

In this study, liquid water-cooling of lithium ion battery packs is analyzed with a multiphysics computational fluid dynamics (CFD) model and a channel geometry is proposed to increase heat removal rates. The three dimensional CFD model geometry consists of two prismatic lithium polymer cells sandwiching a plate with the cooling channels grooved inside. Geometrical and electrochemical parameters of a 40 Ah commercial lithium polymer battery are used in the model. Non-isothermal electrochemical model of the lithium ion battery incorporates energy, charge and species balances in the solid and electrolyte phases with the electrochemical kinetics represented via Butler-Volmer equations. Effects of porous media on the energy, charge and species transport are taken into consideration. Electrochemical battery model is coupled with the flow model developed in the cooling channels. Non-isothermal momentum equation and the energy equation are solved in the cooling channels to account for the thermofluids phenomena.

Channel geometry is initially selected based on logarithmic mean temperature (LMTD) difference method. CFD model is developed based on the characteristic dimensions and the flowrate determined from the LMTD study. In the course of simulations shape and dimensions of the channel are further tuned to achieve a design enhancing heat transfer rates during the operation of the lithium ion battery.

Steady state simulations are carried out to investigate thermal management of the lithium ion battery during typical modes of operation. Temperature gradients and charge distribution inside the battery geometry are identified for different current densities drawn from the battery. A parametric analysis involving different discharge rates up to 8C is conducted. Temperature distribution at each discharge rate is obtained to estimate the possible locations of the spikes during the battery operation. Moreover, thermo-electrochemical behavior of the cell is studied at charging conditions. Charging rates beyond manufacturer recommended maximum of 2C are analyzed to estimate the accompanied rise of cell temperatures in the case of fast charging applications. Model results are exploited as preliminary design recommendations for a more inclusive thermal management system.
In Situ Fabrication of 3-Dimentional Li4Ti5O12/Reduced Graphene Oxide Microspheres with High Tap Density for High-Rate Lithium Ion Batteries
Authors: Kim Myeongseong , Lee Suk Woo , Kim Kwang-Bum
Published: February 2020

Spinel Li4Ti5O12 has attracted much attention as an anode material for lithium-ion batteries because of its good Li-ion intercalation reversibility and extremely small structural changes during charge-discharge cycling. Despite these advantages, Li4Ti5O12 is not suitable for commercial use due to its low electronic conductivity (10-13 S cm-1), which leads to poor rate capabiltiy.1 Several effective ways to improve the rate capability of Li4Ti5O12 have been reported, including reduction of the particle size to the nanoscale, doping Li, Ti, or O sites with small amounts of metal or nonmetal ions, surface modification or carbon coating, and its incorporation into composites with carbonaceous materials.2-4

Among the various carbonaceous materials, reduced graphene oxide (RGO) or graphene nanosheets has attracted considerable interest as electrode materials for electrochemical energy storage because of their unique properties such as high electronic conductivity, large surface area, and good mechanical properties. Some recent studies have demonstrated the excellent rate capability and cycle stability of   Li4Ti5O12/RGO nanocomposites.4 However, in all these reports, the lithium–titanium–oxide (Li–Ti–O)/RGO nanocomposite as the precursor for Li4Ti5O12, was initially synthesized using a two-step or multistep process. In such multistep methods, Li4Ti5O12 particles can be limited the available sizes and morphologies. In addition, it is difficult to fabricate the phase-pure Li4Ti5O12 due to the formation of titanates with several other phases.5

Previously reported Li4Ti5O12/RGO nanocomposites mostly have 2-dimension morphologies with low tap density.4,5 The 2-dimentional Li4Ti5O12/RGO nanocomposites are not suitable for commercial use because their low tap density limits the volumetric energy density. Therefore, a simple and facile synthesis of 3-dimentional Li4Ti5O12/RGO nanocomposites with a high tap density and superior rate capability is highly desirable.

In this study, we report in-situ synthesis of 3-dimentional Li4Ti5O12/RGO microspheres with high tap density, wherein the initial Li-Ti-O/RGO precursor is fabricated by the spray drying method in the presence of all precursors in a solution. Upon subsequent heat treatment, phase-pure 3-dimentional Li4Ti5O12/RGO microspheres with high tap density were successfully synthesized. More detailed on the synthetic procedure, morpology, electrochemical and structural properties of 3-dimentional Li4Ti5O12/RGO microspheres will be presented at the meeting.

 References

 

1. S. G. Doo et al, J. Am. Chem. Soc., 2008, 130, 14930.

2. N. Ohta et al, Adv. Mater., 2006, 18, 2226.

3. N. Jayaprakash et al, Appl. Nanosci., 2011, 1, 7.

4. H. K. Kim et al, Electrochem. Commun., 2010, 12, 1768.

5. H. K. Kim et al, J. Mater. Chem. A, 2013, 1, 14849
Heterostructure of SnO2/TiO2 Nanotubes with Precise Wall Thickness Control As Anodes for Lithium Ion Battery
Authors: Lee Jubong , Kim Myungjun , Lee Seonhee , Seo Seongrok , Bae Changdeuck , Shin Hyunjung
Published: February 2020

Devices of energy storage and conversion draw much attention recently, among the devices, secondary lithium-ion batteries for energy storage will play an increasingly important role. SnO2 as anode materials have attracted a lot of attention and are regarded as one of the most promising candidates for lithium-ion battery, with the theoretical reversible capacity of 782 mAhg-
1 and low enough discharge potential of 0.01V. Like to other alloy-type anode materials, its practical application has been impeded by the poor cycling performance owing to the pulverization and subsequent electrical disconnection of the electrode caused by extremely large volume change (about 300%) during the insertion and extraction processes of lithium ions. Li2O phases, produced by the reaction of SnO2 and lithium ions, are electrochemically inactive, which is the main reason for the large initial irreversible capacity. To overcome this problem, feasible strategy is to design the nanostructure. 1-dimensional nanotubular structures exhibit enhanced cyclability due to the short diffusion path of lithium ions within the wall of nanotubes and the local empty space in the core of tubular structures can accommodate its volume expansion. SnO2 and TiO2 nanotubes as well as their heterostructures were synthesized by anodic aluminum oxide (AAO) template-directed ALD (Atomic Layer Deposition) process. Nanotubes and their heterostructures were characterized by thermogravimetric/differential thermal analysis (TG/DTA), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray diffraction (XRD).  

The wall thickness of nonotubes can be easily controlled by the number of cycles during ALD processes. The porous nanotubes and their heterostructures exhibit high lithium ion storage capacity, fairly high rate performance, and high cyclability when evaluated as anode materials. As expected, the nanotubes of SnO2 with the wall thickness of about 10 nm show the initial capacity of 900 mAhg-1 and reduces down to 300 mAhg-1 after 50 cycle. The conversion reaction of SnO2 to Sn and further Li and Sn alloys were clealy observed by ex sity TEM. Composite heterostructures of TiO2/SnO2
  show much improved cycle performance without any degradation during Li insertion and di-insertion. Advantages of using heterostructure of TiO2/SnO2
  nanotubes as anode materials will be further discussed.

Figure 1
Enabling Aqueous Processing of Cathode Materials for Li-Ion Batteries
Authors: Laszczynski Nina , Kim Guk-Tae , Passerini Stefano
Published: February 2020

Nowadays, Li-ion batteries have become the most promising power source for hybrid and electric vehicles. Considering their environmental friendliness, recycling issues and therefore cost issues, one approach towards greener batteries is the substitution of fluorinated binders like polyvinylidene difluoride (PVdF) that require the use of toxic and highly volatile solvents (e.g. N-methyl-2-pyrrolidone (NMP)), with aqueous binders such as sodium carboxymethyl cellulose (sodium CMC) [1]. Nevertheless, there is a significant drawback associated aqueous processing: slurries become strongly basic due to the reaction of the cathode material with water. This leads to aluminium corrosion of the current collector [2] in addition to the active material degradation.

One strategy to overcome material degradation and aluminium corrosion is the preliminary coating of the active material to prevent its reaction with water. It is then of paramount importance that the active material is not damaged upon coating process and the coating layer itself does not affect negatively the capacity or rate performance of the active material [3-5].

Here, the properties of coated Li-NMC are investigated using different coating approaches and materials. The coated Li-NMC materials were analysed by XRD to study their structure. The positive influence of the coating on the composite Li-NMC electrodes prepared with the aqueous binder is demonstrated, in particular with regard to the prevention of aluminium corrosion. SEM and TEM were used to characterize the composite electrodes, while elemental analysis and TGA were used to investigate the coating, quantitatively. Electrodes of coated and uncoated materials were prepared using the aqueous binder and investigated in terms of their capacity and rate performance to establish the influence of the active material coating.

[1] G.T. Kim, S.S. Jeong, M. Joost, E. Rocca, M. Winter, S. Passerini, A. Balducci, Journal of Power Sources, 196 (2011) 2187-2194.

[2] S.F. Lux, F. Schappacher, A. Balducci, S. Passerini, M. Winter, Journal of The Electrochemical Society, 157 (2010) A320-A325.

[3] M. Bettge, Y. Li, B. Sankaran, N.D. Rago, T. Spila, R.T. Haasch, I. Petrov, D.P. Abraham, Journal of Power Sources, 233 (2013) 346-357.

[4] B. Lin, Z. Wen, J. Han, X. Wu, Solid State Ionics, 179 (2008) 1750-1753.

[5] J. Ni, L. Gao, L. Lu, Journal of Power Sources, 221 (2013) 35-41.

Figure 1
Excellent Stability of a Li-Ion-Conducting Solid Electrolyte upon Reversible Li+/H+ Exchange in Aqueous Solutions
Authors: Chi Miaofang , Ma Cheng , Sakamoto Jeffrey , More Karren L. , Liang Chengdu
Published: February 2020

Batteries with aqueous catholyte and Li metal anode have attracted intensive research interests due to their exceptional energy density and high charge/discharge rate. The long-term operation of such batteries requires particular conditions for the solid electrolyte separator between the anode and aqueous solutions. In addition to the compatibility with Li, the separator must be stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strong basic solutions was observed in a Li-stable solid electrolyte, the cubic Li7La3Zr2O12 garnet. The material experienced a Li+/H+ exchange in aqueous solutions. Nevertheless, its structure remained unchanged even under a high exchange rate of 63.6%. When treated with a 2M LiOH solution, the Li+/H+ exchange was reversed without any structural change. These observations suggest that cubic Li7La3Zr2O12 is a promising candidate for the separator in aqueous lithium batteries.
High-Yield Few Layered Graphene Wrapped Around Hematite As a Superior Anode Material for Lithium-Ion Battery
Authors: Wang Yukun , Yang Lichun , Zhu Min
Published: February 2020

A high performance Fe2O3 based anode material is synthesized via a facile and effective one-step P-milling method. With 15-25 layers FLG nanosheets wrapped around, the electrochemical performance of FLG@Fe2O3 composites is greatly improved. P-milling 20h sample reaches a reversible capacity of 758 mAh g-1 after 300 cycles, which equals to 88% of its theoretic capacity. The wrapping structure of FLG nanosheets plays an important role in improving the electric conductivity and restraining the volume change, which is beneficial for capacity and cycle performance. With the superior electrochemical performance, FLG@ Fe2O3 composites prepared via P-milling could be promising as anodes with high performance and long life for lithium-ion batteries.

Figure 1
Tri-Layered Si/CeO2/Polyaniline Composites As Anode Materials for Lithium-Ion Batteries
Authors: Bai Ying , Tang Yang , Wang Zhihui , Wu Chuan , Wu Feng , Liu Gao
Published: February 2020

Si has very high theoretical specific capacity as an anode material in a lithium-ion battery. However, its application is seriously restricted because of relatively undesirable conductivity and poor cycling stability. Here we report Si/CeO2/Polyaniline (SCP) composite as an anode material, which was synthesized by hydrothermal reaction and chemical polymerization. The structures and morphologies of the SCP composites are characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). It is shown that Si/CeO2 (SC) particles are well coated by polyaniline (PANI) elastomer which has good electrical conductivity. The SCP shows larger reversible capacity and better cycling performance compared with pure Si. The first reason is that CeO2 can protect Si from reacting with electrolyte.  More importantly, the PANI elastomer can accommodate the volume change of the composite during Li-alloying/dealloying processes, so the pulverization of silicon would be significantly reduced. The SCP material can retain a capacity nearly 775 mAh/g after 100 cycles, while pure Si only shows a capacity of 370mAh/g after 100 cycles.
Generation of Agsi Film By Magnetron Sputtering for Use As Anodes in Lithium Ion Batteries
Authors: Polat Deniz Billur , Eryilmaz Levent , Keles Ozgul
Published: February 2020

In the present work we deposit Si film with 20%at. Ag, to improve the capacity retention and the cycleability of Si anode. The physical properties of the as-synthesized sample is investigated by thin film X-ray diffraction (XRD) and scanning electron microscopy (SEM). The as-prepared sample is used as negative electrode materials for lithium ion battery, whose charge-discharge properties, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and cycle performance are examined in detail. The galvanostatic test result shows that the electrode delivers 1800 mAh/g initially with 99% Coulombic efficiency and retains 85% of its initial discharge capacity after 50 cycle. This outstanding property of the electrode can be related to the presence of Ag, which decreases the polarization of the anode.

Keywords: Ag based anodes, lithium ion batteries, magnetron sputtering.
Lithium Sulfide/Carbon (Li2S/C) Electrode Preparation in Hydrogen Sulfide (H2S) Flow and Its Electrochemical Performance
Authors: Dressel Carina B , Jha Himendra , Gasteiger Hubert A , Fässler Thomas F.
Published: February 2020

Energy storage for automotive and portable devices is one of the main research topics today and in the future. Today’s batteries based on Li-ion technology are not up to par with the demands of long-range vehicles[1]. The solutions to this problem are beyond Li-ion technologies, e.g. Li/S or Li/air. Possible distances of >400 km or >550 km for Li/S or Li/air, respectively, compared to today’s 160 km with Li-ion technology are desirable[2]. The biggest obstacle in Li/S and Li/air batteries are safety concerns due to the use of elemental lithium as anode material[3]. This may be overcome by using a Li2S cathode, equivalent to the discharged state of the Li/S battery, and a lithium free anode such as carbon.

Since Li2S is very moisture sensitive, preparation of Li2S electrodes needs to be in a very controlled environment. We invented a new method to produce Li2S/C electrodes in a H2S flow, by using various lithium salts as starting materials. This way the air-sensitive Li2S is introduced in the electrode in the very last step. This lowers the process costs and allows an easier handling of the electrodes during preparation, since it is less moisture sensitive. Furthermore it might allow the use of aqueous binder systems which is novel for Li2S electrodes.

Electrodes containing a lithium salt, carbon and a binder were cast and after drying exposed to H2S. The resulting electrode consists of lithium sulfide, carbon and the binder. The reaction is confirmed by X-ray diffraction and elemental analysis. The morphology and homogeneity of the electrode is investigated by scanning electron microscopy. Galvanostatic cycling of the Li2S/C electrode validates the new method.

[1] X. Ji, L.F. Nazar, Advances in Li–S batteries, Journal of Materials Chemistry, 20 (2010) 9821.

[2] P.G. Bruce, S.A. Freunberger, L.J. Hardwick, J.M. Tarascon, Li-O2 and Li-S batteries with high energy storage, Nature materials, 11 (2012) 19-29.

[3] J.M. Tarascon, M. Armand, Issues and challenges facing rechargeable lithium batteries, Nature, 414 (2001) 359-367.