bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bulk and Surface Modifications in High Ni Cathode Materials
Authors: Pinedo Ricardo , Weber Dominik , Weldert Kai , Zeier Wolfgang , Janek Jürgen 
Published: February 2020

High energy-density lithium ion batteries (LIBs) are in demand for portable electronic devices and electrical vehicles. Since the energy density of these batteries relies heavily on the cathode material, a great deal of attention is being focused on developing alternative materials with a higher degree of Li utilization and specific energy density [1]. In particular, layered Ni-rich oxides can deliver higher capacities at lower cost than the conventional LiCoO2(LCO). However, there are still several problems associated with their cycle life, thermal stability, and safety, which need to be solved [2]. In addition, these drawbacks increase with increasing Ni amount, and motivate major research efforts to understand, mitigate and overcome these effects.
In stoichiometric layered lithium metal oxides, every vacant tetrahedral site is coordinated by either 3 lithium ions and 1 transition-metal (TM) ion, or 1 lithium ion and 3 TM ions. Effectively, only in the first case at least two Li sites are connected and can therefore sustain lithium migration. Hence, for each Li diffusion channel in the layered structure, exactly one gate site is a TM site, while the second one is a lithium site [3]. The barrier for lithium migration through such a 1-TM channel is correlated to the TM valence and the areal lithium-TM separation. The latter varies with the width of the Li layer (the distance between TM-O slabs), constraining the degree of local relaxation for the TM when lithium enters the activated state [4]. Nevertheless, the Li slab distance highly varies during discharge-charge processes and leads to cell volume fluctuation which is considered a potential source of electrode degradation, as it could favor the formation of microcracks [5]. Moreover, this fluctuation increases with increasing Ni amount.
One promising approach to control the Li slab distance in high Ni materials is anionic substitution [6]. In this work, the effect of N and F dopants is evaluated and a correlation between structural parameters and electrochemical performance was established. Moreover, the effect of N and F can be restricted to the materials surface. The stabilization of surfaces in high Ni materials is a fundamental challenge in order to control the aging processes of these materials.

References

[1]. W. Liu et al., Angew. Chem. Int. Ed.
2015, 54, 4440.
[2]. L. Wu et al. Chem. Mater.
2011, 23, 3953.
[3]. A. Urban et al., Advanced Energy Materials
2014, 4, 1400478.
[4]. K. Kang et al. Phys.
Rev. B
2006, 74, 094105.
[5]. R. Hausbrand et al., Materials Science and Engineering: B
2015, 192, 3.
[6]. F. Kong et al., J. Mater. Chem. A
2015, 3, 8489.
Enhanced Rate Capability in Two Phase Reaction in LiFePO4 By Interfacial Modification Between Cathode and Electrolyte
Authors: Orikasa Yuki , Yoshinari Takahiro , Kato Eri , Mori Takuya , Nakanishi Koji , Uchimoto Yoshiharu 
Published: February 2020

Olivine-type LiFePO4 is considered as a promising cathode material for high power density lithium-ion battery. Lithium-ion intercalation proceeds thorough a two-phase reaction divided into LiFePO4 and FePO4. During the phase transition between LiFePO4 and FePO4, the nucleation of a new phase occurs at the electrode / electrolyte interface, which is reported to be the rate determining reaction.1 To improve the rate capability of LiFePO4, Park et al performed the surface modification by nitrogen on LiFePO4 particles.2 However, their improved mechanism is not clearly understood due to the difficulty in the observation of electrode / electrolyte interface. In order to analyze the electrode / electrolyte interface, thin-film electrodes and surface sensitive X-ray absorption spectroscopy are powerful tool.3 In this study, we prepared LiFePO4thin-film model electrodes to clarify the reaction kinetics and applied the interfacial modification of nitrogen. Their reaction mechanism is discussed with the information of X-ray absorption spectroscopy.
LiFePO4 thin-film was prepared on a polycrystalline Au substrate by pulsed laser deposition method. The deposition was conducted under Ar atmosphere (0.0001 Pa) at 923K for 30 min. The prepared thin films were annealed under ammonia gas at 873 K. The obtained thin-film was characterized by X-ray diffraction and TEM. X-ray absorption spectroscopy at Co K-edge was performed at BL37XU, Spring-8. N K-edge X-ray absorption measurements were performed in Ritsumeikan SR-center. For the electrochemical analysis, three-electrode cells employing Li metal as a counter and a reference electrode, and 1 M LiClO4in propylene carbonate liquid electrolyte were prepared.
Annealing of ammonia gas introduces nitrogen into LiFePO4 surface, which is confirmed by N K-edge X-ray absorption spectra. The rate capability of the nitrogen modified LiFePO4 thin-film electrodes is improved. The surface sensitive Fe K-edge X-ray absorption spectra show the increasing of oxidation state in iron, which implies the lattice mismatch is decreased in surface of LiFePO4. Therefore, nucleation reaction is enhanced during two phase reaction between LiFePO4 and FePO4, which is the origin of surface modification effect.
References
[1] Delmas, C.; Maccario, M.; Croguennec, L.; Le Cras, F.; Weill, F., Nat. Mater.
2008,
7(8), 665.
[2] Park, K. S.; Xiao, P. H.; Kim, S. Y.; Dylla, A.; Choi, Y. M.; Henkelman, G.; Stevenson, K. J.; Goodenough, J. B., Chem. Mater.
2012,
24(16), 3212.
[3] Takamatsu, D.; Koyama, Y.; Orikasa, Y.; Mori, S.; Nakatsutsumi, T.; Hirano, T.; Tanida, H.; Arai, H.; Uchimoto, Y.; Ogumi, Z., Angew. Chem. Int. Edit.
2012,
51(46), 11597.
Acknowledgement
This work was supported by JSPS KAKENHI Grant Number 25249141.
Cus-Carbon Composite As Cathode Material for Lithium Secondary Batteries
Authors: Li Yong , Liu Wen , Guo Rui , Pei Haijuan , Xie Jingying 
Published: February 2020

The Li/CuS battery was a promising high-energy battery system because of the good electronic conductivity of 103 S cm-1 and a high theoretical capacity of 560 mAh g-1 for CuS.[1-3]In this paper, S/C/nano-Cu composite was prepared by a fast deposit method in an aqueous solution. Then the S/C/nano-Cu composite was dried at 60℃ in a vacuum oven for 24h and the CuS/C composite was further in situ formed in the process of drying.
CuS/C composite cathode for a lithium rechargeable battery is tested with 1 M LiFSI/DOL-DME as electrolyte at room temperature. The cathode undergoes a two-step reaction during the initial discharge to 1.5 V with a specific capacity of 546.6 mAh g-1(see Figure 1a). Meanwhile, the composite also exhibits a good cycle behavior with 86.2% capacity retention after 30 cycles at 0.5 C (Figure 1b). These results suggest that the nano-size composite plays an important role during the charge-discharge process and the CuS/C composite is a promising cathode material for high-energy lithium secondary battery.
Figure 1. (a) Initial charge-discharge curves of the CuS/C composite cathode; (b) cycle performance of the CuS/C composite cathode at 0.5 C.

Acknowledgements

This work is supported by Shanghai Science and Technology Committee Rising-Star Program (15QB1402000).

Reference

[1] R.J. Jasinski, Electroanal. Chem. 26 (1970) 189.
[2] J.S. Chung, H.J. Sohn, J. Power Sources 108 (2002) 226.
[3] Y.R. Wang, X.W.Zhang, P.Chen, H.T.Liao, S.Q.Cheng, Electrochimica Acta 80 (2012) 264.

Figure 1
Post-Mortem Analysis of Commercial NMC/Graphite Li-Ion Pouch Cells within Mat4Bat European Project
Authors: Iturrondobeitia Amaia , Aguesse Frédéric , Waldmann Thomas , Kasper Michael , Wohlfahrt-Mehrens Margret , Bekaert Emilie 
Published: February 2020

Li-ion batteries are good candidates for electric vehicles and stationary applications due to their high power and energy densities. It is well known that the lifetime of lithium ion batteries is limited by undesirable side reactions. Moreover, these side reactions can affect different parts of the battery including the electrolyte, the active material, binder, conducting agents, current collectors and the separator. Over time, this fact leads to a gradual capacity fade and the end of life of the battery. Thus, the understanding of degradation mechanisms in lithium ion batteries is considered to be of great importance.
In this work, the “post mortem analyses“ of NMC/graphite commercial pouch cells has been performed. For this, a standard procedure for cell opening and preparation of the samples has been defined. As safety plays an important role in the dissemination of batteries, full discharge of the investigated cells has been carried out [1,2,3]. Furthermore, a controlled environment such as an Ar-filled glove box has been used during cell opening in order to avoid material decomposition [4,5]. Once the electrodes have been separated, the conductive salt has been removed to prevent corrosion. Diagnostic evaluation of the first degradation mechanisms has been studied by ex-situ destructive physico-chemical and electrochemical analyses of the cell components. The crystallographic and morphological studies of the electrodes have been carried out by X-ray diffraction (XRD) and electron microscopy (SEM). Additionally, elemental analysis of the electrode composition has been determined by EDS and ICP techniques. In order to evaluate the electrochemical characterization of the harvested electrodes, galvanostatic testing in half-cell configuration has been performed.
The research leading to these results has been performed within the MAT4BAT project (http://www.mat4bat.eu)
[1] D. Aurbach, B. Markovsky, A. Rodkin, M. Cojocaru, E. Levi, H.-J. Kim, Electrochimica Acta 47 (2002) 1899.
[2] Y. Kobayashi, T. Kobayashi, K. Shono, Y. Ohno, Y. Mita, H. Miyashiro, Journal of the Electrochemical Society 160 (2013) A1181.
[3] T. Waldmann, M. Wilka, M. Kasper, M. Fleischhammer, M. Wohlfahrt-Mehrens, Journal of Power Sources 262 (2014) 129.
[4] H.-Y. Amanieu, D. Rosato, M. Sebastiani, F. Massimi, D.C. Lupascu, Materials Science and Engineering: A 593 (2014) 92.
[5] C. Wu, Y. Bai, F. Wu, Journal of Power Sources 189 (2009) 89.
Effects of Mesoscopic Microstructural Features on the Effective Ionic Diffusivity of Solid Electrolytes for Li Batteries
Authors: Heo Tae Wook , Wood Brandon C. 
Published: February 2020

The kinetics of ion transport in solid electrolytes is known to be highly sensitive to the topological characteristics of ion conduction pathways. The conduction mechanisms usually involve concurrent ionic diffusion along a variety of mesoscopic features of internal microstructures such as bulk grain, structural domains, and associated boundaries as well as their network. Due to the complexity of these structural features of the solid electrolytes during operation, it is significantly challenging to characterize the microstructure-ionic diffusion property relationship. For better mechanistic understanding of relevant conduction mechanisms, it is necessary to thoroughly explore the impacts of individual microstructural factors on the overall kinetic properties and performances. In this presentation, we will present our development of an efficient mesoscopic computational method for extracting the effective diffusivity of the solid electrolyte containing arbitrarily distributed microstructural inhomogeneities such as differently oriented multiple grains, several structural variants of phase domains, and grain/domain boundaries. Using two- and three-dimensional digital microstructures generated by phase-field simulations as well as the fundamental diffusivity tensors of reference phases and boundaries derived from atomistic calculations as inputs, the method enable us to efficiently compute the effective diffusivity tensor of the entire system. We will then discuss the applications of this framework to investigating the relationship between relevant individual microstructural features and effective diffusivity of highly conductive solid electrolytes (e.g., LLTO and LLZO) focusing on the impacts of topological features of grains, internal mesoscopic structures of high- and low-temperature phase domains, and grain/phase boundary networks.
*This work of was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Evaluation of Commercial High Energy Lithium Primary Cells for Wide Temperature Range Aerospace Applications
Authors: Krause Frederick C. , Jones Simon C. , Brandon Erik J. , Ratnakumar Bugga V. , Jones John-Paul , West William C. , Pasalic Jasmina , Billings Keith J. 
Published: February 2020

As NASA missions become increasingly demanding of robust, lightweight, and compact power sources, there is a need to develop long-life and high-energy battery systems. Lithium-ion batteries have been developed at JPL over the last two decades and have been successfully integrated into a number of NASA missions [1] in conjunction with solar arrays and radioisotope thermoelectric generator (RTG) power sources. In the case of short-term missions in extremely harsh conditions (i.e., thirty days or less and/or at temperatures reaching -40 °C) without an active thermal management system, lithium primary cells may be considered for their high specific energy, especially in environments where recharging secondary cells would be challenging [2]. The icy moons of the Jovian system, for example, offer little sunlight for photovoltaic power and Jupiter’s intense magnetosphere leads to constant potentially damaging radiation.
Many types of commercial lithium primary cells are available, reportedly offering high specific energies of ~500 Wh kg-1, with some designed specifically for low temperature operation. These commercial cells must be validated for space missions with extensive testing to demonstrate their performance, safety, reliability, and suitability for space environments. Radiation tolerance is also an important consideration, both as a method of sterilization for planetary protection and for survival in high radiation environments.
In the present study, we have evaluated a number of commercial lithium primary cells (ranging from AA to DD+ sizes) of varying chemistries (with CFx, MnO2, SOCl2, SO2, and FeS2 cathodes) and manufacturers for possible future use in NASA’s deep space missions. We have assessed various performance characteristics of these cells, including low temperature energy, rate capability, and tolerance to radiation exposure, which will be reported here.

Acknowledgement

The work described herein was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by the NASA Space Technology Mission Directorate Game Changing Development Program.

References

[1] Ratnakumar, B. V., Smart, M. C., Huang, C. K., Perrone, D., Surampudi, S., & Greenbaum, S. G. (2000). Lithium ion batteries for Mars exploration missions.Electrochimica Acta, 45(8-9), 1513–1517. doi:10.1016/S0013-4686(99)00367-9
[2] J.F. Whitacre, W.C. West, M.C. Smart, R. Yazami, G.K. Surya Prakash, A. Hamwi, et al., Enhanced Low-Temperature Performance of Li – CF x Batteries, Electrochem. Solid-State Lett. . 10 (2007) A166–A170.doi:10.1149/1.2735823
System Theoretic Analysis of Battery Charging Optimization
Authors: Vincent Tyrone , Weddle Peter , Kee Robert J. , Tang Gongguo 
Published: February 2020

Lithium-ion batteries have attractive features for many applications, and are widely used as high-energy density storage devices. The internal electrochemical and chemical reactions occurring during charge/discharge make Li-ion batteries sensitive to demand sequences and operating conditions. Battery management systems are necessary to keep cells within acceptable operating ranges to prolong life, reduce charging losses, and mitigate failure. One particular area of recent investigation is incorporating pulsed perturbations in charging protocols. Typical arguments for pulsed perturbations involve reduced chemical impedance and reduced electrode/electrolyte polarization which decrease losses, and electrode diffusion capabilities which can reduce losses and mitigate plating. However, published experimental and simulation evidence is contradictory, with some either arguing in favor pulsed charging and some indicating no effect or worse performance. While experimental results are useful, the measurable results are subtle enough that experimental conditions and uncertainty can be a plausible argument against both positive and negative results. In this work, we ask the following question: What are the features of a battery as a dynamic system that must appear in order for optimal charging sequences to include a periodic component? The answer to this question is then used to illuminate whether some of the physical, mechanistic explanations for the positive effects of perturbations are valid.
The analysis considers two cases: finding the current trajectory to minimize the energy required to supply a fixed amount of charge to a battery, and finding the current trajectory to maximize the charge supplied to the battery while meeting constraints on internal variables related to the deposition of lithium on the anode electrode. Under the assumption that the trajectories for the relevant battery parameters can be predicted using a linear time-invariant dynamic system, analytic solutions are obtained. Using these analytic solutions, we extract conditions on the battery model that must be satisfied in order for the solutions to contain a periodic component. In the case of energy minimization, it can be shown that the the electrochemical impedance must approach the imaginary axis, while in the case of meeting constraints, a necessary condition is developed involving the response of the internal variables to an impulse in charging current. By examining the impedance spectra and impulse responses of typical Li-ion batteries, these results indicate that that pulsed or sinusoidal perturbations do not appear in the optimal charging sequence. It should be emphasized that this analysis does not provide definitive arguments for or against pulse charging or any evidence against any particular experimental results. However, this study provides important guidance when considering a physical explanation for the benefits of pulsed or sinusoidal ripple charging.

Figure 1
Breathable Polymer Encapsulation of Lithium Battery Electrode Materials Ensures Durable Cyclic Performance of Si Anode
Authors: Chu Peter Po-Jen , Tsai Minghan , Hsieh Y.S. 
Published: February 2020

Silicon Anode is considered a most critical component for advanced lithium battery since it has about 10 folds higher theoretical capacity than that of conventional graphite anode. However, Si suffers from huge volume change during lithiation/ delithiation process has led to pulverization and the formation of unstable SEI layer with the electrolyte that quickly deteriorated the cyclic performance of lithium battery. In this study, smart polymer material bearing breathable network-like structure is employed to encapsulate the high energy anode material through photo polymerization. The monomers of the smart polymer in the solvent are adsorbed first to the surface of silicon particle, followed by photo-polymerization to form the dendrimer network-like structure which homogeneously encapsulated the active anode. During charging and discharging process, the flexible and breathable protection layer effectively retained the pulverized anode materials due to the huge volume change, and avoided a direct contact with the liquid electrolyte. Both functions are essential to inhibit the dissolution of active material and responsible for maintaining the cyclic performance of Si anode battery. NMR spectroscopy is used to follow the photo-polymerization identified, and the effect of the coating and the change of morphology after extensive charge and discharge cycle are identified by SEM and TEM. Current results show the coating of a network-like breathable polymer protection layer is effective in preserving the integrity and the structure of Si anode, leading to improved life cycle performance.
Interfacial Li-Ion Storage Between Graphene Layers
Authors: Liu Tianyuan , Park Jinho , Joiner Corey A , Lee Seung Woo , Navaei Milad , Stern Ilan 
Published: February 2020

The ever increased development of portable devices and electrical vehicles demands the electrochemical energy storage devices with high energy and power densities. Graphite has been the most widely used anode materials for Li-ion batteries. However, because of its low theoretical capacity (372 mAh/g), there has been significant efforts in developing electrode materials with much higher energy densities. Graphene, a one-atom-thick carbon materials showed numerous advantages including superior electrical conductivity, thermal conductivity and high surface area; and is expected to be a good candidate as a high-power and high-energy electrode material for Li-ion batteries. Although, previous studies used graphene as anode materials, it showed significantly enhanced capacity >1000 mAh/g; the energy storage mechanism in graphene is still unclear. This is due to the high density of defects in chemically synthesized graphene. Few studies have been using chemical vapor deposition (CVD)-grown defect-free single layer graphene (SLG) on copper foil as anodes in Li-ion batteries.1 Despite this, the exact mechanism of Li ions storage in the SLG is still a subject of controversy. Theoretical study has shown that the absorption of Li-ions on defect-free SLG is energetically unfavorable.2 This is in controversy with the experiments which claims that CVD-grown SLG is promising electrode materials for Li anodes. In this study, we investigated the Li-ion storage in CVD-grown SLG graphene in comparison with Cu substrate, our results confirmed that the capacity obtained for SLG on Cu is mainly originated from the contribution of Cu substrate. However, by using bilayer or triple layer graphene which is prepared by a layer-by-layer transfer process, we found that the Li ion storage capacity will be significantly enhanced when additional layer graphene was placed on the top of initial SLG. The capacitance increased from 0.05 F/cm2 for Cu substrate to 0.08 F/cm2 for bilayer graphene on Cu and further increased to 0.129 F/cm2for triple layer graphene on Cu substrate. The areal capacity of the bilayer graphene is ~ 2 times of the capacity available for Cu substrate after 50 cycles. Our study indicates that the interfacial space between graphene layers plays a critical role for high performance Li-ion storage.

References:

1. D. Wei, S. Haque, P. Andrew, J. Kivioja, T. Ryhanen, A. Pesquera, A. Centeno, B. Alonso, A. Chuvilin and A. Zurutuza, Journal of Materials Chemistry A, 2013, 1, 3177-3181.
2. E. Lee and K. A. Persson, Nano Letters, 2012, 12, 4624-4628.