bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interfacial Reactivity of a High Capacity Manganese Rich (HCMRTM) Li-Ion Positive Electrode
Authors: Terborg Lydia , Park Yirang , Venkatachalam Subramanian , Hernandez Pedro , Kostecki Robert 
Published: February 2020

High capacity manganese rich (HCMR™) materials are promising candidates for commercial Li-ion battery positive electrodes for applications in electric and plug-in hybrid electric vehicles.1 These oxides, also denoted as xLiMO2 - (1-x)LiMnO3 (M = Co, Mn, Ni), deliver a high discharge capacity (>240 mAh/g) at operating voltages exceeding 3.5 V vs. Li/Li+.2 However, these materials have significant limitations and suffer from high first cycle irreversible capacity loss, impedance rise and voltage fade during cycling.2-4 Extensive studies of HCMR™ electrodes indicate a structural modification/ rearrangement as one of the major reasons for the electrode/material degradation. In this work, the surface and interfacial phenomena of HCMR™ electrodes were investigated using in situ and ex situ spectroscopic techniques as a function of electrode potential and charge/discharge cycling.
HCMR™ materials surface structural changes were investigated during electrochemical cycling by confocal Raman microscopy in a custom-designed spectro-electrochemical cell. A carbon- and binder-free cathode was prepared by pressing the active material onto Al foil, which is then loaded into the spectro-electrochemical cell. Figure 1 shows Raman spectra collected during a first charge-discharge cycle. Surface structural changes due to the delithiation of the HCMR™ material are observed by the change in position of the Raman peaks during cycling.
While the oxidation of Ni2+ to Ni4+ appears to be a fully reversible process, other surface structural changes manifest themselves during the prolonged cycling (Figure 2). A shift of the major peak Mn-O band from 595 cm-1 to higher frequency, as well as an increase in intensity for another Mn-O mode at 650 cm-1 was observed.
Shifting from the Raman spectra indicates significant structural deviation of the HCMR™ material during cycling. The correlation of the structural changes with the observed interfacial phenomena will be discussed in regards to their influence on the electrode and cell electrochemical performance and lifetime.

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, under the Applied Battery Research for Transportation (ABR) Program and Award Number DE-EE0006443.

References

1. M. M. Thackeray, S. H. Kang, C. S. Johnson, J. T. Vaughey, R. Benedek and S. A. Hackney, J Mater Chem, 17, 3112 (2007).
2. Y. Li, M. Bettge, B. Polzin, Y. Zhu, M. Balasubramanian and D. P. Abraham, J. Electrochem. Soc., 160, A3006 (2013).
3. K. J. Carroll, D. Qian, C. Fell, S. Calvin, G. M. Veith, M. F. Chi, L. Baggetto and Y. S. Meng, Phys Chem Chem Phys, 15, 11128 (2013).
4. D. Mohanty, A. S. Sefat, S. Kalnaus, J. L. Li, R. A. Meisner, E. A. Payzant, D. P. Abraham, D. L. Wood and C. Daniel, J Mater Chem A, 1, 6249 (2013).

Figure 1
Mechanistic Insights into Rechargeability and Capacity Limitations in Nonaqueous Li-O2 Batteries
Authors: McCloskey Bryan D 
Published: February 2020

Li-air batteries have received significant attention as a potential high specific energy alternative to current state-of-the-art rechargeable Li-ion batteries.1-3 However, numerous scientific challenges remain unsolved in the pursuit of attaining a battery with high capacity and modest Coulombic efficiency. This presentation will highlight efforts to improve Li-air battery cyclability and capacity through studies that elucidate the mechanism of Li2O2 electrochemical formation and oxidation at the positive electrode. Results will be presented confirming that Li-O2 battery capacity is limited by Li2O2-induced cathode electronic insulation and rechargeability is limited by electrolyte and electrode instabilities in the presence of Li2O2.4-5 Strategies to circumvent both of these challenges will be discussed.6

(1) Bruce, P. G.; Hardwick, L. J.; Abraham, K. M. Lithium-air and lithium-sulfur batteries. MRS Bulletin
2011,
36, 506-512.
(2) Girishkumar, G.; McCloskey, B.; Luntz, A. C.; Swanson, S.; Wilcke, W. Lithium−air battery: promise and challenges. J. Phys. Chem. Lett.
2010,
1, 2193-2203.
(3) Christensen, J.; Albertus, P.; Sanchez-Carrera, R. S.; Lohmann, T.; Kozinsky, B.; Liedtke, R.; Ahmed, J.; Kojic, A. A critical review of Li/air batteries. J. Electrochem. Soc.
2012,
159, R1-R30.
(4) McCloskey, B. D.; Valery, A.; Luntz, A. C.; Gowda, S. R.; Wallraff, G. M.; Garcia, J. M.; Mori, T.; Krupp, L. E. Combining accurate O2 and Li2O2 assays to separate discharge and charge stability limitations in nonaqueous Li-O2 batteries. Journal of Physical Chemistry Letters
2013,
4, 2989- 2993.
(5) Viswanathan, V.; Thygesen, K. S.; Hummelshoj, J. S.; Norskov, J. K.; Girishkumar, G.; McCloskey, B. D.; Luntz, A. C. Electrical conductivity in Li2O2 and its role in determining capacity limitations in non-aqueous Li-O2 batteries. J. Chem. Phys.
2011,
135, 214704.
(6) Luntz, A. C.; McCloskey, B. D. Nonaqueous Li–air batteries: a status report. Chemical Reviews
2014, Article ASAP.
Analysis of Diffusion Behavior in Lithium-Air Batteries Via Simulated and Experimental Impedance Spectroscopy and Equivalent Circuit Modeling
Authors: Nelson Ruben , Weatherspoon Mark H. 
Published: February 2020

Porous electrodes offer the advantage of high surface area in a compact structure and play an important role in the diffusion process in batteries. Particular to lithium-oxygen (Li-O2) batteries, diffusion of oxygen from an external source complicates transport properties due to the consideration of multiple active species at multiple phases and oxygen diffusion complexity. General diffusion from transport processes that normally result in relaxation time constants then may not apply. Instead a complex frequency response may occur, which may be explained by blocking electrode behavior.
In Li-O2 cells featuring binder-free electrodes with metal oxide catalyst material (1), rough surfaces and possible non-uniform current distribution may generate interesting impedance spectra from stochastic errors and depressed time constants. Previous studies by de Levie (2) and Bisquert (3-5) generally investigate via transmission line circuit models the impedance exhibited by porous electrodes. This work aims to apply the basis of a transmission line model like Figure 1 with the experimental impedance spectra of a Li-O2 cell with a lithium metal electrode and a carbon cloth coated cobalt, manganese composite oxide discharged and charged more than ten times (6). The circuit model estimates the thickness of the oxide, or length of the model pore, in terms of the number of resistor-constant phase elements (R-CPE), and the impedances along the line. The observed diffusion impedance and its frequency dispersion estimated by repeated R-CPE elements includes a terminating impedance at the end of the line, indicating what the impedance at the boundary where diffusion of the species to the electrode surface should occur. The impedance spectra of the experimental cell has high negative reactance values at the lower frequencies as shown in Figure 2. This capacitive nature is suggestive of a blocking behavior exhibited by electrodes where little faradaic current or charge transfer occurs, such as in the case of electrodes completely coated by a nonconductive oxide.
Acknowledgements
This work was supported by the ERC program of National Science Foundation under award number EEC-08212121.
References
1. J. Gomez, E.E. Kalu, R. Nelson, C. Akpovo, M.H. Weatherspoon, J.P. Zheng, ECS Electrochemistry Letters, 1, (2012) D25-D28.
2. R. De Levie, Electrochimica Acta, 8, (1963) 751-780.
3. J. Bisquert, Physical Chemistry Chemical Physics, 2, (2000) 4185-4192.
4. J. Bisquert, G. Garcia-Belmonte, Á. Pitarch, ChemPhysChem, 4, (2003) 287-292.
5. J. Bisquert, A. Compte, Journal of Electroanalytical Chemistry, 499, (2001) 112-120.
6. R. Nelson, M.H. Weatherspoon, J. Gomez, E.E. Kalu, J.P. Zheng, Electrochemistry Communications, 34, (2013) 77-80.

Figure 1
In Situ Observation of Sodiation and Magnesiation of ZnO Nanowire Compared to Lithiation Process
Authors: Asayesh-Ardakani Hasti , Nie Anmin , Klie Robert F , Shahbzian-Yassar Reza 
Published: February 2020

The over-growing demand of high capacity storage for application in electrical vehicles and green power backup energy has triggered the new battery concept search beyond Li-ion. Na-ion and Mg multivalent rechargeable batteries are recent concepts. The natural abadency of Na and Mg on earth makes these batteries more eco-friendly and affordable. Another considerable issues in batteries are performance and cyclability of batteries. The anode materials usually experience large volume changes through the ion insertion and extraction. This volume change and lithium embrittlement usually causes cracks and loss of contact in the anode material, which ultimately causes the failure of battery. Here, we investigated and compared the structural and mechanical changes of ZnO nanowires during sodiation and magnesiation to lithiation process by using in situ transmission electron microscopy. The cracks were created upon the first lithiation process of single crystalline ZnO nanowire. The lithiated ZnO nanowire shows multiple glassy domains, which has low strength and ductility. This results in poor cyclability of battery. On the other hand, ZnO nanowires do not show any cracks and degradation after sodiation and magnesiation. The direct comparison between Na and Mg-ion batteries to most consumed Li-ion battery would pave the new search for high capacity battery.
Revealing the Thermodynamics of Magnesium and Lithium Ion Insertion Chemistry in Ultrafast Discharging Hybrid Rechargeable Batteries
Authors: Aykol Muratahan , Kim Soo , Cho Jae-Hyun , Ha Jung-Hoon , Chung Kyung Yoon , Kim Kwang-Bum , Cho Byung-Won , Wolverton Chris 
Published: February 2020

We present a combined experimental and theoretical strategy to design dual-salt Mg2+/Li+ batteries with very high electrochemical performance.[1] In this work, we first investigate the (co)-insertion mechanisms of Mg2+ and Li+ ions into the Mo6S8 cathode by using density functional theory (DFT) calculations together with the Nernst relation. We show that there exists a threshold for the Li+ activity in the electrolyte above which lithiation is preferred instead of magnesiation. Based on the DFT results, to achieve high electrochemical performance, we suggest an approach to control the insertion chemistry by varying the Li salt content of the electrolyte. Using this approach, we have carefully revealed the ion insertion chemistry for the Mg-metal anode/Mo6S8cathode hybrid Mg/Li batteries with all-phenyl complex (APC) and LiCl electrolytes.
Our experimental results confirm that at low Li+ activities in the electrolyte, Mg2+ insertion dominates and the battery can cycle only below 80 mAh g-1, whereas at high Li+ activities, fast Li+ ionic transport in the entire intercalation range leads to higher voltage, capacity and rate capability. We find that the Mg/Li hybrid rechargeable battery with an APC 0.2 M and LiCl 0.5 M dual-salt electrolyte has a remarkable electrochemical performance. This hybrid battery with optimized insertion chemistry achieves 93.6% capacity retention at 20 C and 87.5% at 30 C at room temperature. Our combined computational and experimental study suggests an effective route to develop new dual-salt hybrid systems with controlled insertion chemistry.

Acknowledgement

This work has been supported by The Dow Chemical Company and Northwestern-Argonne Institute of Science and Engineering (NAISE).

References

[1] J.-H. Cho, M. Aykol, S. Kim, J.-H. Ha, C. Wolverton, K. Y. Chung, K.-B. Kim, and B. -W. Cho, J. Am. Chem. Soc.
2014, 136, 16116.
Does Pseudocapactive Charge Storage Take Place in Nanoparticulate TiO2 and Li4Ti5O12 Anodes?
Authors: Opitz Martin , Yue Junpei , Wallauer Jens , Smarsly Bernd , Roling Bernhard 
Published: February 2020

Titanium oxide-based materials, such as TiO2 and Li4Ti5O12 (LTO), are considered as interesting alternative anode materials for lithium ion batteries. In order to increase the interfacial area between TiO2 particles and the battery electrolyte and in order to reduce the diffusion length for Li+ ions within the particles, both materials have been extensively studied. [1], [2] Thereby, indication has been found that the charge storage is not entirely due diffusion-controlled Faradaic charge storage, but also due to pseudocapacitive charge storage. [3], [4]
We studied nanoparticlate LTO electrodes and compared this to Li storage in Nb-doped TiO2 particles. Using scan rate-dependent cyclic voltammetry, we determined the amount of Faradaic and of pseudocapactive charge with the same method that was reported in the literature [1], [4]. Thereby, we discovered that the application of this method leads to unphysical results, which is originated in the iso-potential plots of the scan-rate dependent current density. We show that even for simple prototype Faradaic reactions, such iso-potential plots yield an apparent pseudocapacitance.
References
[1] J. Wang, J. Polleux, J. Lim, B. Dunn, J. Phys. Chem. C 111 (2007) 14925–14931.
[2] D. Wang, X. Wu, Y. Zhang, J. Wang, P. Yan, C. Zhang, D. He, Ceramics International 40 (2014) 3799–3804.
[3] T. Brezesinski, J. Wang, J. Polleux, B. Dunn, S.H. Tolbert, Journal of the American Chemical Society 131 (2009) 1802–1809.
[4] P. Yu, C. Li, X. Guo, J. Phys. Chem. C 118 (2014) 10616–10624.
Direct Synthesis of Non-Stoichometric Nanocrystalline Metal Oxides and Their Composites: Improving the Reversibility and Current Capability of Lithium-Ion Batteries
Authors: Takeuchi Kenneth J , Marschilok Amy C , Takeuchi Esther S 
Published: February 2020

As the demand for large scale batteries grows, considerations such as earth abundance, cost, and toxicity gain increased significance. Metal oxides are worthy of evaluation as active materials for electrochemical energy storage, particularly those utilizing earth abundant, low cost, environmentally benign metal centers. However, to facilitate broader implementation of metal oxides in batteries, improvements to current capability and reversibility are needed.
Some metal oxides adopt close-packed coordination environments, which optimize ion density. However, ion and electron transfer are challenges which may or may not be exacerbated as a result of high ion density. An emerging paradigm for the implementation of close-packed materials in higher current applications is the tuning of the materials crystallite dimensions, where the reduction of crystallite size should minimize the path length for ion transport upon discharge, resulting in a reduction of both internal cell resistance and the resultant structural strain associated with lithium insertion. Significant improvements in current capability of metal oxides and their composites via direct crystallite size control and other strategies will be described.
The synthetic approaches described in this presentation will provide new strategies which may be applicable toward development of other new classes of materials and composites with energy or energy storage applications.
An Investigation of the Impact of Protic Impurities, Different Housing Materials and Silicon on the Thermal Aging of Electrolytes Used in Lithium-Ion Batteries
Authors: Handel Patricia , Fauler Gisela , Kapper Katja , Schmuck Martin , Stangl Christoph , Fischer Roland , Uhlig Frank , Koller Stefan 
Published: February 2020

Concerning prospective energy storage, lithium-ion batteries (LIBs) are one of the most outstanding technologies due to their high energy density as well as great cycle stability. To increase their operational lifetime, thermal degradation of the most common conductive salt lithium hexafluorophosphate LiPF6 (1) should be avoided. Therefore, it’s crucial to minimize traces of protic impurities resulting from e.g. organic carbonates. In fact, the products of the endothermic equilibrium of LiPF6 are preferably formed at higher temperatures, leading to the formation of hydrofluoric acid (HF) and subsequently to further degradation of electrolyte components. (2)
LiPF6 (s) LiF (s) + PF5(g) [1]
PF5 (g) + H2O (l) → O=PF3(g) + 2 HF (l) [2]
Lux et al. (3) followed the HF formation in LiPF6 containing electrolytes by spectroscopic ellipsometry of SiO2 layers. As we reported recently (4), SiO2 probably promotes the degradation of LiPF6 in organic carbonate based electrolytes.
Herein, we report about the decomposition of 1M LiPF6 in a binary mixture of ethylene carbonate and diethylene carbonate in a ratio of 40:60 (w/w) at ambient and elevated temperature (cf. table 1). Degradation products are studied by nuclear magnetic resonance spectroscopy (NMR, cf. figure 1), gas chromatography mass spectrometry (GC-MS) and headspace GC-MS (HS-GC-MS). Acid-base and coulometric titration are used to determine the total amount of acid and water content upon aging, respectively. Ultraviolet-visible (UV-Vis) spectroscopy is used to follow the color change of the electrolyte (cf. figure 2). The influence of protic contamination, different housing materials and added active materials on the electrolyte aging is shown.

Acknowledgement

VOLKSWAGEN VARTA Microbattery Forschungsgesellschaft and Herbert Quandt Foundation are gratefully acknowledged for funding.

References

1. K. Xu, Chem. Rev., 104, 10 (2004).
2. C. L. Campion, W. Li, B. L. Lucht, J. Electrochem. Soc., 152, A2327 (2005).
3. S. F. Lux, I.T. Lucas, E. Pollak, S. Passerini, M. Winter, R. Kostecki, Electrochem. Commun., 14, 47 (2012)
4. P. Handel, G. Fauler, K. Kapper, M. Schmuck, C. Stangl, F. Fischer, F. Uhlig, S. Koller, J. Power Sources, 267, 255 (2014).

Figure 1
Designing New Conductive Imidazole-Derived Salt for Lithium-Ion Battery Electrolytes: A Computational Approach
Authors: Leggesse Ermias Girma , Jiang Jyh-Chiang 
Published: February 2020

Ever since the commercialization of the rechargeable Li-ion cell, LiPF6 is by far the most widely used electrolyte salt. It can produce electrolyte solutions with a superior ion conductivity, good electrochemical oxidation stability, and adequate thermal stability when dissolved in binary or ternary solvent systems of cyclic carbonates. However, LiPF6is also reported to have series problems that may lead to performance and safety issues (1). In order to circumvent these issues, researches have focused on designing new lithium salts which have thermal and electrochemical stability, high ionic conductivity and easy synthesis route (2-6).
In this work, we report designing of an alternative salt derived from bis(trifluoroborane)imidazolide (LiIm(BF3)2) by employing density functional theory (DFT) calculations. New anion structures were generated by considering substitution at the C5 position with electron withdrawing groups (-F, -CF3, -SO3H and -NO2) and electron donating groups (-NH2, -OCH3 and –CH3). By using the optimized anion structures, random lithium ion-pair configurations (around 130 structures for each) were generated and optimized to identify the most stable configurations. The effects of different substituents were investigated with respect to ion dissociation energies, anion oxidative stability, and aromaticity of the molecules. Based on our calculations, we have found that, ion dissociation energies and intrinsic oxidative potentials of the anions were largely affected by the type of substituents introduced on the parent structure. Compared to –PF6 and -Im(BF3)2 (standard anions), –CF3 and -NO2 substituted anions showed an increase in anion oxidation stability. Since, BF3 occupies the strong Lewis basic sites of the imidazole ring, the parent structure itself exhibit a charge delocalization over the aromatic ring, which results in a weak coordinating ability with Li+. With the exception of –F, -CF3 and –CH3, further introduction of substituents at C5 position led to a much lower cation–anion interaction. Among the possible anions studied, 5-nitro-bis(trifluoroborane)imidazolide, with oxidation potentials > 5.7 V vs. Li+/Li , can be considered as a good candidates for high voltage Li-ion battery applications. Moreover, we have also found that the ion-pair dissociation energy, and anion stability of the selected salt are much improved compared to experimentally reported LiIm(BF3)2 and LiPF6.
References
1. K. Xu, Chem. Rev., 104, 4303 (2004).
2. J. Scheers, E. Jonsson, P. Jacobsson and P. Johansson, Electrochemistry, 80, 18 (2012).
3. K. Angenendt and P. Johansson, J Phys Chem B, 115, 7808 (2011).
4. P. Johansson and P. Jacobsson, J Power Sources, 153, 336 (2006).
5. E. Jonsson and P. Johansson, Phys Chem Chem Phys, 14, 10774 (2012).
6. J. Scheers, L. Niedzicki, G. Z. Zukowska, P. Johansson, W. Wieczorek and P. Jacobsson, Phys Chem Chem Phys, 13, 11136 (2011).

Figure 1
A Silicon-Graphene Electrode with Multilayered Structure for High Performance Lithium-Ion Batteries
Authors: Gao Xianfeng , Li Jiangyang , Xie Yuanyuan , Yuan Chirs 
Published: February 2020

A silicon-graphene electrode composed of porous Si and reduced graphene oxide with multilayered structure was synthesized from bulk Si particles through inexpensive electroless etching and graphene self-encapsulating approach. The prepared composite electrode presents superior electrochemical performance with a discharge capacity of 1026 mAh/g tested at 1A/g and good retention rate. The columbic efficiencies are about 99% during the whole cycling process. The electrode was extensively characterized and it is found that the superior performance attributes to the novel multilayered structure with porous Si particles encapsulated, which effectively accommodate the large volume change during the lithiation/delithiation process and provide increased electrical conductivity. This facile approach offers an alternative route to construct promising low cost Si electrode for future industrial applications.