bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using XPS to Determine the Relative Thickness of Lithium-Ion Surface Films at the Negative Electrode
Authors: Somerville Limhi , Bareno Javier , Prezas Panos D. , Basco John K. , Jennings Paul , McGordon Andrew , Lyness Christopher , Duong Tien Q. , Bloom Ira 
Published: February 2020

During typical lithium-ion cell usage over application lifetimes (e.g. automotive) they form a film, which is nanometres thick, on the surface of the negative electrode which helps to passivate against further reaction. Its chemical composition and thickness affect capacity and power capabilities of a cell through 1. Consumption of lithium inventory during the surface film forming reactions and 2. More surface film which increases surface resistance. Over time and with further cycling, this film thickens. Understanding and controlling surface film thickness and composition as well as its relationship to cell operating conditions could provide a pathway to extend cell and device service life.
As a first step toward achieving this goal we focused on characterising surface film thickness as a function of cell age and operating conditions. Currently, there is no reliable method for determining surface film thickness at the electrode surface. We tested the capacity and power of commercial 18650-sized cells cycled at different C-rates or stored at different temperatures and states of charge. We then present a method of XPS analysis to determine the relative surface film thicknesses within each of these three conditions. XPS analysis was completed at two different institutions on two different systems to determine reproducibility.
The novel XPS method reliably showed that the surface film thickness increased with temperature, state of charge and higher C-rates.
We found that the chemical composition of the surface film changed as a consequence of temperature, State of charge and charge rate. We also found that the thickness of the surface film followed traditional 1-dimensional models of surface film growth, that is, a sharp initial growth followed by a reduced rate after ‘X’ months / C-rate.
These findings indicate that, using our method, it is possible to determine the relative thickness of the negative electrode surface film. It also showed that surface film thickness increased with cell charge- rate, temperature and SoC. This is invaluable in determining the relationship between cell conditions and its effect on internal chemical composition of the cell.
The work at Argonne National Laboratory was performed under the auspices of the U.S. Department of Energy (DOE), Office of Vehicle Technologies, under Contract No.
DE-AC02-06CH11357.
The submitted issue has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-Eng-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, non-exclusive, irrevocable, worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
Activated Lignin Based Carbon Nanofibers As Binder-Free Anodes for Lithium Ion Batteries
Authors: Stojanovska Elena , Serife Pampal Esra , Kilic Ali 
Published: February 2020

Anode, as a constituent element of a battery is the crucial component for battery’s cycle life and rate capability. Anodes with different zero-, 1D-, 2D- and 3D nanostructures made of different materials have been proposed. Among them 1D carbon nanofibers (CNF) can provide shorter lithium ion diffusion lengths, electron transport and enhanced surface area. The possibility for adding different active materials into their structure and their usage as free standing electrodes are another advantages of CNF. Another approach to improve battery performances increasing their surface area by activating the carbonaceous material.
Lignin is abundant low-cost polymer obtained from a variety of biomasses by solvent extraction as most common method. As a byproduct of paper industry it can be used as fuel additive, emulsifier or dispersant in agriculture, as binder or reinforcement in different composite structures, as antioxidant for polymers. Due to its highly functionalized macromolecules can be used as starting material for renewable polymers, such as polyesters, polyurethanes or polyanilines. Besides, its high carbon content allows its usage as precursor polymer for carbon production. As non-toxic and biocompatible polymer is promising precursor to replace PAN in carbon fiber production. However, its low molecular weight is an obstacle for its conversion into nanofiber. One approach to overcome this problem is blending it with high molecular weight polymers, such as poly (vinyl alcohol), polyethylene oxide, poly acrylonitrile, polyethylene glycol, polypropylene, etc.
In this study, lignin/PVA blends were converted into nanofibers by electrospinning. The fibrous structure was further stabilized under iodine vapor and then carbonized in inert atmosphere. Activation of the carbonaceous structure was realized by dissolving the polymers into basic aqueous solution and completed by neutralization with acidic aqueous solution. In order to study the effect of the degree of activation on electrochemical properties, solutions with different KOH concentrations were prepared. As prepared carbon nanofibers were used as free-standing anodes without addition of current collector in a half cell button type Li-ion battery. The change in morphology of the fibers was characterized by SEM, while the change in their chemical structure by RAMAN spectroscopy. Battery rate capability and cycling stability were analyzed by galvanostatic cycling test. The results showed activated lignin-based carbon nanofibers can improve the cycling stability and rate capability when used as anodes in Li-ion batteries.
Atom Probe Tomography Study on Lithiation Behavior in Silicon Alloy Electrodes
Authors: Zheng Yueming , Pradeep Konda Gokuldoss , Renner Frank Uwe 
Published: February 2020

With respect to its high specific capacity, silicon would be an ideal replacement for carbonaceous anodes in lithium-ion batteries. But the usage of silicon-based active materials has been hindered by its tremendous volume change and related problems during lithiation cycles. To mitigate the problems, the silicon particles are often used as (expensive) nanoparticles, or some recent strategies include confined Si precipitates embedded in a matrix material. Among others, for example, Si/Ti4Ni4Si7 (STN) has been recently proposed [1]. However, the lithiation mechanisms remain poorly understood for either pure silicon or silicon alloys, due to the silicon (and silicon alloy) amorphization induced by lithiation. We consider Atom Probe Tomography (APT) as a powerful tool [2] to understand the mechanisms of lithium insertion and interaction in silicon alloy electrodes. APT is enabling for a sub-micron sample prepared by Focused Ion Beam (FIB) to address the elemental distribution at the atomic level. Our results propose a strong contribution of interfaces in such nano-scale Si alloys [3]. In the discharged state we revealed a core-shell structure with the formation of a Li-rich shell surrounding a pure silicon core. Hereby, not only an accurate composition of this shell is determined by APT, but also the lithium atom position in the matrix is provided. We believe that this study will be beneficial not only for silicon alloys, but also for understanding pure silicon lithiation mechanisms.
[1] Son et al. “A Highly Reversible Nano-Si Anode Enabled by Mechanical Confinement in an Electrochemically Activated LiXTi4Ni4Si7 Matrix.” Advanced Energy Materials 2 (2012), 1226.
[2] Diercks et al., Microscopy of Chemical and Mechanical Heterogeneities in Lithium Cobalt Oxide, Microscopy and Microanalysis 21 (2015), 523.
[3] Y.Zheng, KG. Pradeep, F.U. Renner et al., to be published.
Figure 1. The atom probe tomography reconstruction of Silicon atoms in pristine Si/Si7Ti4Ni4.

Figure 1
New Findings in the Degradation of LiNi1-x-yCoxMnyO2 Cathode Material By Transmission Electron Microscopy
Authors: Xu Zhongling , Lang Ye , Gao Pengfei , Liu Na , Wang Long 
Published: February 2020

Phase transitions and the related phase identifications for the layered rhombohedral Li(Ni1/3Co1/3Mn1/3)O2 with different electrochemical experience have been studied by transmission electron microscopy. The preliminary results show the existence of two types of new phases: spinel and rocksalt phases. The phase transition from rhombohedral to spinel phase happened only after formation and distributed on the surface of the particles, while the layered rhombohedral structure was kept inside.Another rocksalt phase was also identified on the surface of cycled sample which may getting thicker with the number of cycles. The phase transition from layered rhombohedral phase to spinel and then the rocksalt phase may explain the increased DCR and the capacity loss during cycling and storage. The twinning domains of layered rhombohedral phase were also found on the surface of the crystallite after 60°C storage at discharged state. The twinning domains on the surface may block the Li+ diffusion space between the layers of the bulk, and thus make contribution to the DCR increase during storage.
Simulation of Lithium Dendrite Growth: Surface Morphology Effect
Authors: Byun Seoungwoo , Park Joonam , Appiah Williams Agyei , Lee Taejoo , Lee Young-Gi , Ryou Myung-Hyun , Lee Yong Min 
Published: February 2020

Li metal has been considered as an anode material for lithium secondary batteries (LSBs) for over four decades. However, its uncontrolled chemical reactivity towards organic solvents and dendritic growth at random in electrochemical cells delayed its commercialization in the secondary battery market. Thus, without developing stable Li metal electrode, we will not encounter lithium-oxygen (Li-O2) and lithium-sulfur (Li-S) batteries as well as lithium metal secondary battery forever. However, regardless of tremendous endeavour to control the Li metal, unfortunately, the dendrite formation and growth mechanism has not been fully understood owing to the limited analysis in operando.
Therefore, we try to contruct a mathematical model to study the current distribution upon the Li metal and the growth rate of dendrites with a simulation tool, COMSOL Multiphysics 5.2. Since this simulation contains a moving electrode surface during electrodeposition process, the deformed geometry should be considered carefully. From these simulated results, we can have different dendrite growth behaviours depending on initial Li metal surficial morphology.

References

1. V. Srinivasan and J. Newman, Journal of the Electrochemical Society, 151, A1530 (2004).
2. P. Arora, M. Doyle, A. S. Gozdz, R. E. White and J. Newman, Journal of power Sources, 88, 219 (2000).

Acknowledgements

This work was supported by the international Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No. 20158510050020) and by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977).

Figure 1
Electrochemical Reduction from a Single Particle to the Systems Level
Authors: Marschilok Amy C , Kirshenbaum Kevin , Bock David C , Brady Alexander B , Zhong Zhong , Takeuchi Kenneth J , Takeuchi Esther S 
Published: February 2020

Understanding electrochemical behavior requires inquiry of the material fundamental properties as well as the behavior of the material when configured into a fully functioning device. Thus, the ability to use local electrochemical probes and integrate the results with system level behavior is needed. In this work, quantitative electrochemistry was conducted on individual particles of vanadium phosphorous oxides, (specifically SVPO, AgwVxPyOz) cathode materials. Silver ions incorporated into the layered vanadium phosphorous oxide structure facilitated monitoring of the reaction progress through the formation of silver metal. The results obtained from the single particle were related to the systems level through in-situ examination of the reduction progress in fully assembled cells probed through energy dispersive x-ray diffraction, EDXRD.
At the particle level, individual particles of active material, Ag2VO2PO4, were electrochemically reduced to various depths of discharge. After the material was reduced, the conductivity of the individual particles was determined using a nanoprobe integrated with a scanning electron microscope, Fig. 1. The individual particles showed a drastic reduction in local resistance when discharged.
At the system level, in situ energy dispersive X-ray spectroscopy (EDXRD) was used to probe Li/ Ag2VP2O8 cells at several stages of reduction, allowing depth profile analysis of the discharge process. This technique enables micron scale spatial resolution of reduced Ag2VP2O8 and Ag0 discharge products in the bulk electrode. Results suggest the formation of a 3-dimensional Ag0 percolation network that increases conductivity throughout the entire electrode, occurs concurrently with a substantial decrease in the charge transfer resistance. The resistance of the reduced cathode is dependent upon discharge rate even in the presence of conductive additives.
Development of the next generation of battery systems with improved energy utilization requires accessing all of the active material in an electrode. The multiscale inquiry methodology described provides a template for future investigations of both particle level and system level properties of electrochemically discharged materials highlighting the importance of advanced instrumental techniques to gain insight into complex discharge processes.

Figure 1
Functional Electrolyte Additives for Improved Performance and Gas Suppression in Li4Ti5O12 / LiMn2O4 Li-Ion Battery Systems
Authors: Hoffmann Jennifer , Milien Mickdy S , Lucht Brett L , Li Jing , Payne Martin 
Published: February 2020

Li4Ti5O12 (LTO) as a material for lithium ion batteries has garnered attention from industry and academia due to its increased safety properties, high rate capabilities, and exceptional cycling stability. The main concern arises in that cells using LTO anodes produce gas especially at elevated temperatures leading to swelling and decreased performance. It has been reported that this gassing is associated with the electrolyte and salt decomposition on the catalytic surface of the LTO anode1,3. In the open literature, efforts have been made to address the gassing issue through either coating on LTO materials2,4 or electrolyte technology3. In this work, we investigate the impact of various additives to the LTO-based cell performance in an electrolyte stabilization approach. Additives presented, including an electrolyte stabilizer, improved the electrochemical performance and reduced the gassing of pouch cells using LTO as anode and LiMn2O4 (LMO) as cathode. These results of electrochemical tests, surface analysis of the anode and cathode through XPS and FTIR will be discussed in the meeting. The results presented prove that electrolyte stabilization through use of functional additives can allow the benefits of LTO to be harnessed and the gassing behavior to be controlled.

References

Y. He, B. Li, M. Liu, C. Zhang, W. Lv, C. Yang, J. Li, H. Du, B. Zhang, Q. Yang, J. Kim, F. Kang, Sci. Rep. 2, 913 (2012)

L. Wang, K. Nakura, M. Imazaki, N. Kakizaki, K. Ariyoshi, and T. Ohzuku, J. Electrochem. Soc., 159, A1710 (2012)

J. Liu, P. Bian, J. Li, W. Ji, H. Hao, A. Yu, J. Pow. Sour., 286 (2015)

W. Li, X. Li, M. Chen, Z. Xie, J. Zhang, S. Dong, M. Qu, Elect. Acta., 139 (2014)
Evaluation of Electrolyte Resolution Behavior of 18650 Type Lithium Ion Battery By NMR Measurements
Authors: Haruna Hiroshi , Takamatsu Daiko , Hirano Tastumi , Takahashi Shin , Tanaka Yasutaka 
Published: February 2020

Li-ion batteries are currently used in portable electronic and power tool and electric vehicles and grid energy applications due to their high energy density. The development of higher power, higher capacity and longer life batteries becomes more pressing. Current cycle life may be insufficient. One method to developing longer life cells is to use electrolyte additives such as vinylene carbonate to electrolyte solution which has been shown to significantly increase lifetime [1].In this report, the effects of vinylene carbonate an electrolyte additive were studied to improve battery life. VC was added to electrolyte solution to examine the impact in the solution structure change before / after cycling tests by 18650-type battery cells. All solutions were extracted from cycled 18650- type cells to detect solution composition by nuclear magnetic resonance (NMR) techniques.Compared with the case of no additives, VC that was included at 1 wt% concentration in the electrolyte at the initial state was reduced to half after only one cycle. Then it was completely consumed after 100 cycles due to be reacted at the interphase of positive/negative electrodes. Then the electrolyte composition change in until 100 cycles was slightly different with the addition of VC detected by NMR measurement. However, after 1000 cycles both electrolytes showed substantially the same composition. Ethyl methyl carbonate (EMC) which was one component of the electrolyte solution was decomposed and degradation products were produced in electrolyte solution. And the products were detected dimethyl carbonate and diethyl carbonate as the ester exchange reaction of EMC [2]. Furthermore NMR results showed poly-carbonate species from the polymeric reaction ethylene carbonate with non cyclic carbonate. Those were revealed by 1D as 1H or 13C NMR and 2D HMQC techniques. We will discuss relations of the resolution mechanism of the electrolyte with the degradation of the battery.
[1] J. Self, C.P. Aiken, R. Petibon, J.R. Dahn, J. Electrochem. Soc. 162(2015) A796-A802. [2] E. S. Takeuchi, H. Gan, M. Palazzo, R. A. Leising, S. M. Davis, J. Electrochem. Soc. 144(1997) 1944-1948.
Role of 1, 3-Propane Sultone and Vinylene Carbonate in Solid Electrolyte Interface (SEI) Formation and Gas Generation
Authors: Zhang Bo , Metzger Michael , Solchenbach Sophie , Payne Martin , Meini Stefano , Gasteiger Hubert A. , Garsuch Arnd , Lucht Brett L 
Published: February 2020

Due to the uprising demand of energy storage in consumer electronics and electric vehicles, tremendous effort and interest have been drawn into the development of novel electrolyte additive blends in lithium-ion batteries (LIBs). However, the applications of LIBs have several critical limitations, including elevated temperature performance, calendar life performance, and safety. The solid electrolyte interface (SEI), generated from the electrolyte reduction on the anode surface during the first few cycles, is believe to be one of the key players improving LIBs thermal stability. Various attempts to screen ultimate electrolyte additive blends and produce robust SEI layer for better cyclability in lithium-ion batteries operations at elevated temperature have been widely reported. The graphite/LiNi1/3Co1/3Mn1/3O2 coin cells containing electrolytes with and without 1, 3-propane sultone (PS) and vinylene carbonate (VC) have been prepared and investigated. The electrochemical performance of the cells is correlated with ex-situ surface analysis of the electrodes conducted by FTIR and XPS, and in-situ gas analysis by on-line electrochemical mass spectrometry (OEMS). The results suggest that incorporation of both PS and VC results in improved capacity retention upon cycling at 55 °C and lower impedance. Ex-situ surface analysis and OEMS confirm that incorporation of PS and VC alter the reduction reactions on the anode inhibiting ethylene generation and changing the structure of the solid electrolyte interface (SEI). Incorporation of VC results in CO2 evolution, formation of poly(VC), and inhibition of ethylene generation. Incorporation of PS results in generation of lithium alkylsulfonate (RSO2Li) and inhibition of ethylene generation. The combination of PS and VC reduces the ethylene gassing during formation by more than 60 %.
Investigation of NaxMgx/2Mn1-x/2O2 (1.0 > x > 1/3) for Na-Ion Battery Positive Electrodes
Authors: Zheng Lituo , Nguyen Peter , Obrovac Mark N 
Published: February 2020

Introduction

Manganese-based layered oxide materials are promising positive electrode for sodium ion batteries. It has been shown that the partial substitution of Mn with Mg can smooth the voltage curve and improve the cycling stability.1 Mg substitution can also induce the activation of the redox reaction of oxide ions.2 In this study, the NaxMgx/2Mn1-x/2O2 (1.0 ≥ x ≥ 1/3) series of layered oxides were synthesized and characterized in Na cells.

Experimental

Stoichiometric amounts of MgO, MnO and Na2CO3 were combined by ball milling, then heated at 900 ºC in air to obtain samples of
NaxMgx/2Mn1-x/2O2. Electrodes were made with active material, PVDF binder, carbon black at a ratio of 8:1:1 and dried under vacuum at 120 ℃ overnight. 1M NaPF6 in a solution of EC, DEC, FEC (volume ratio 3:6:1) was used as electrolyte and Na foil was used as counter/reference electrode. X-ray diffraction (XRD) patterns were measured with a Rigaku Ultima IV X-ray diffractometer equipped with a Cu anode X-ray tube and a diffracted beam monochromator.

Results and discussion

Figure 1 shows the XRD patterns of NaxMgx/2Mn1-x/2O2 (1.0 ≥ x ≥ 1/3). All the samples were found to be P2-dominant, even when x approachs 1. The sample with x = 2/3 has the highest P2 phase purity. The further x deviates from 2/3, the more impurities are present in the XRD patterns.
Figure 2 shows the voltage curve of Na2/3Mg1/3Mn2/3O2. Na2/3Mg1/3Mn2/3O2 was found to have a reversible capacity of ~250 mAh/g (corresponding to a theoretical energy density of approximately 520 Wh/kg) with 80% capacity retention after 20 cycles. The voltage curve exhibits a plateau at > 4 V during the first charge, and a slope between 1.5 V and 3.5 V during discharge. The loss of capacity of the 4 V plateau during cycling indicates irreversible structure changes upon first charging, possibly due to oxygen loss. After about 10 cycles, the 4 V plateau becomes stabilized and the material cycles reversibly.
The voltage curve of Na2/3Mg1/3Mn2/3O2 is consistent with the voltage curve of Li2MnO3, wherein all the Mn is also in the 4+ oxidation state. This result is the first report of the reversible sodium extraction from layered manganese oxide materials where all the Mn exist as Mn4+.
References
1. J. Billaud et al., Energy Environ. Sci., 7, 1387-1391 (2014)
2. N. Yabuuchi et al., J. Mater. Chem. A, 2, 16851-16855 (2014)

Figure 1