bluuebunny/crossref_metadata_2025 huggingface dataset:
In-Situ and First Principles Characterization of Alpha-Manganese Oxide (MnO2)
Authors: Ford Denise , Yang Zhenzhen , Park Joong Sun , Trahey Lynn , Ren Yang , Kim Soojeong , Kim Hacksung , Fister Timothy T , Thackeray Michael M. , Chan Maria K. Y.
Published: February 2020

Alpha manganese oxide (α-MnO2) is of interest as a cathode material for lithium-ion batteries and as an electrode/electrocatalyst for hybrid Li-ion/Li-O2 systems. It has a tunnel structure with large 2x2 channels that accommodate different species such as Ba2+, K+, NH4
+, or H3O+/H2O. Characterization and modeling of the insertion and removal of Li, oxygen, and H3O+/H2O species under electrochemical cycling and heating is important for understanding how MnO2 acts as a hybrid Li-ion/Li-O2 battery material. In this talk, we will discuss our work in using in-situ synchrotron X-ray diffraction (XRD), X-ray absorption near-edge spectroscopy (XANES), in-situ UV resonance Raman spectroscopy, and density functional theory (DFT) calculations, to unravel the changes in α-MnO2during electrochemical cycling as well as dehydration process. We found evidence of oxygen incorporation and partial removal during electrochemical cycling, as well as two-stage water removal during heating. Both processes involve facile oxygen diffusion through the center of 2x2 tunnels.

Keywords: MnO2, in-situ XRD, DFT

Reference:

Z.-Z. Yang, D. Ford, J.-S. Park, Y. Ren, S. Kim, H. Kim, T. Fister, M. K. Y. Chan,# M. M. Thackeray,# “Probing the release and uptake of water in α-MnO2•xH2O,” Chemistry of Materials 29, 1507–1517 (2017).

Z. Yang, L. Trahey, Y. Ren, M. K. Y. Chan,# C. Lin, J. Okasinski, and M. M. Thackeray, “In-Situ High-Energy Synchrotron X-ray Diffraction Studies and First Principles Modeling of α-MnO2 Electrodes in Li-O2 and Li-ion Coin Cells,” Journal of Materials Chemistry A 3, 7389-7398 (2015).

Acknowledgements:

This work was supported as a part of the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Basic Energy Sciences under award number DE-AC02–06CH11. Use of the Advanced Photon Source, a US DOE Office of Science User Facility operated by Argonne National Laboratory, was supported by DOE under Contract No. DE-AC02-06CH11357. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Figure 1
Swelling-Suppressed Si/Siox Wrapped in Graphene for High Performance Li Storage Material
Authors: Yoo Hyundong , Park Eunjun , Kim Hyekyoung , Bae Juhye , Chang Hankwon , Kim Dae Sik , Jang Hee Dong , Kim Hansu
Published: February 2020

Si as an anode material for lithium-ion batteries has high theoretical capacity(3,580 mAhg-1), but Si has critical technical problems for its commercial such as poor cycle performance associated with severe volume changes during lithium insertion and desertion. In this work, we synthesized Si/SiOx nanospheres enveloped by reduced graphene oxide(rGO) shell layer using aerosol spray pyrolysis. Free void spaces between rGO envelop and Si/SiOx effectively accommodated the volume changes of silicon during cycle. Thus rGO wrapped SiOx nanospheres showed high reversible capacity of about 914 mAhg-1 with excellent capacity retention up to 200 cycle. In the presentation, more detailed microstructural characterization and electrochemical properties of the rGO wrapped Si/SiOx nanosphere anode material will be discussed.
Electrochemical Degradation Processes of Solid Polymer Electrolytes in Li-Ion Batteries: An Online Electrochemical Mass Spectrometry (OEMS) Study
Authors: Sun Bing , Sångeland Christofer , Brandell Daniel , Mindemark Jonas , Berg Erik J.
Published: February 2020

Li-ion polymer batteries are considered as a promising energy storage solution with respect to battery safety and processing flexibility. Recent advances towards fast Li+ transport and room-temperature ion-conduction in solid polymer electrolytes (SPEs) open up great possibilities promoting their implementations in all-solid-state electronics; amongst the viable candidates functionalized polycarbonates and polyesters have shown their versatility to be applied in all-solid batteries which can operate down to ambient temperatures [1]. Nevertheless, there is a general lack of knowledge about the interfacial chemistry and the electro-/chemical degradation schemes of polymer electrolytes, primarily due to the technical obstacles in sample preparation and reliable in-situ characterization.

In the present study, the gaseous decomposition products from polycarbonate and polyester-based SPEs are traced by online electrochemical mass spectrometry (OEMS). An operando characterization of the evolved gases from poly(trimethylene carbonate) (PTMC)-derived SPEs using high-molecular-weight PTMC and its copolymer as the host materials is performed under both cathodic reduction and anodic oxidation regions at close to ambient temperatures (e.g., 30 °C, 50 °C). Direct correlations between the oxidation and reduction potentials with the gas evolution are observed; the evolutions of CO2 (m/z = 44) and CH4 (m/z = 16) are traced and compared with LiTFSI-containing carbonate liquid electrolyte. Meanwhile, additional gaseous products are detected, such as SO2 (m/z = 64), which could be assigned to LiTFSI decomposition. This was indicated from the detectable salt decomposition residuals in Li-cells using PTMCnLiTFSI-based SPEs by X-ray photoelectron spectroscopy (XPS) [2].

References

[1] B. Sun, J. Mindemark, K. Edström, D. Brandell, Solid State Ionics, 262 (2014) 738-742;  J. Mindemark, B. Sun, E. Törmä, D. Brandell, J. Power Sources, 298 (2015) 166-170; Kimura, M. Yajima, Y. Tominga, Electrochem. Comm., 66 (2016) 46-48.

[2] B. Sun, C. Xu, J. Mindemark, T. Gustafsson, K. Edström, D. Brandell, J. Mater. Chem. A, 3 (2015) 13994-14000.
(Invited) Towards High Cycle Efficiency of Si Based Negative Electrodes for Next Generation Lithium Ion Batteries
Authors: Xiao Xingcheng , Zhang Qinglin , Verbrugge Mark W , Sheldon Brian W. , Chen Zhongwei
Published: February 2020

Si is an attractive negative electrode material for lithium ion batteries due to its high specific capacity (~3600 mAh/g). However, the huge volume swelling and shrinking during cycling leads to several coupled mechanical and chemical degradation at the material/electrode/cell level, including fracture of Si particles, unstable solid electrolyte interphase (SEI), and low Coulombic efficiency. In this talk, we will discuss how to improve the cycle efficiency from those aspects, starting with the fundamental understanding of the relationship between the structure and properties of SEI to pinpoint the SEI failure mechanisms using advanced in-situ electrochemical tools. Then we will discuss how to develop artificial SEI, combining the design of Si nanostructure and electrode architecture to enable the high cycle efficiency and the extended life. At last, we will discuss how the nanostructure design at material level can impact the electrochemical-mechanical behaviors at electrode and cell level and the trade-off between gravimetric energy density and volumetric energy density for EV applications.
A Combinatorial Model of the Effect of Additives in High-Voltage, NMC Cells
Authors: Bloom Ira , Sahore Ritu , Peebles Cameron , Abraham Daniel P , Gilbert James A
Published: February 2020

Coin cells containing the additives, vinylene carbonate (VC) and tris(trimethylsilyl)phosphite (TMSPi), in the range of 0 to 0.020 wt. fraction, were cycled between 3.0 and 4.4 V. The changes in C/10 and C/1 capacity and cell resistance at 60% SOC were found to follow linear-with-time kinetic rate laws. After aging, the electrodes were characterized by X-ray photoelectron spectroscopy. The concentration of some surface species correlated very strongly with changes in cell performance.

Further, the cell performance data could be modeled using a statistics of mixtures approach. The modeling indicated that there was a strong, synergistic interaction between VC and TMSPi, as expected. The interaction between these additives lessened capacity fade. These results, as well as others, will be discussed.

Acknowledgment

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 U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, 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.
Improvement of Li-Garnet Interface and in Situ Neutron Depth Profiling Diagnose
Authors: Wang Chengwei , Gong Yunhui , Xie Hua , Zhang Lei , Liu Boyang , Wang Howard , Wachsman Eric D. , Hu Liangbing
Published: February 2020

Solid state electrolytes are known for non-flammability, dendrite blocking, and stability over large potential windows. Garnet-based solid state electrolytes have attracted much attention for their high ionic conductivities and stability with lithium metal anodes. However, high interface resistance with lithium anodes hinders their application to lithium metal batteries. Herein, we develop several efficent and effective techniques that exhibit a significantly improved contact and lead to an interface resistance as low as ~ 7 Ω·cm2. We also use neutron depth profiling (NDP), a nondestructive and uniquely Li-sensitive technique, to reveal the interfacial behaviors of garnet SSE in contact of metallic Li through monitoring Li plating-stripping processes in situ. The NDP measurement has demonstrated the predictive capabilities for diagnosing short-circuits in garnet-based solid state batteries. Two types of cells, symmetric lithium/garnet/lithium (LGL) cells and asymmetric lithium/garnet/carbon-nanotubes (LGC) ones have been fabricated to emulate the behavior of Li metal and Li-free Li metal anodes, targeting full-cell applications with Li-free cathode (e.g., sulfur, and oxygen) and Li-containing cathode (e.g., LiCoO2, LiFePO4, etc.), respectively. The NDP data implies the limitation of Li-free Li metal anode in forming reliable interfacial contacts, and strategies of excessive Li and better interfacial engineering need to be investigated.
Modeling Electrolyte Influence on Stability and Interfacial Structure of Functionalized LiMn2O4 Battery Cathodes
Authors: Letchworth-Weaver Kendra , Nicolau Bruno G. , Ghadar Yasaman , Knight Chris , Gewirth Andrew A , Chan Maria K. Y.
Published: February 2020

Creating an artificial cathode-electrolyte interface (CEI) from self-assembled monolayers of phosphonic acids offers a promising avenue to prevent capacity loss in Li-ion batteries due to metal dissolution from the cathode. A complete theoretical description of the complex and inherently multi-scale interface between the battery electrode surface and an organic electrolyte can enable rational design of such functionalized cathode coatings. We first present a microscopically informed continuum model for organic electrolyte [1,2] which reproduces key solvation phenomena relevant to battery operation. We go on to predict how the structure and energetics of the metal oxide cathode in Li-ion batteries change due to the presence of liquid electrolyte. We find that compared to vacuum calculations [3], the voltage stability window of the Li-terminated (001) and (111) surfaces of the spinel LiMn2O4 (LMO) cathode in solution is enhanced. Furthermore, we demonstrate that our solvation model, in combination with density-functional theory and classical molecular dynamics, simultaneously captures both the formation of a stable artificial CEI on the LMO surface and the interaction of the CEI molecules with the electrolyte. Our theoretical description captures the experimentally observed trends in solubility and cyclic voltammetry of the coated LMO surface, demonstrating how adjusting the length and functionalization of the phosphonates can balance the competing needs of maximizing Li-ion conductivity but minimizing cathode dissolution.

Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

[1] K. Letchworth-Weaver and T.A. Arias, Phys. Rev. B. 86, 075140 (2012).

[2] D. Gunceler et al, Modelling Simul. Mater. Sci. Eng. 21,074005 (2013).

[3] R. Warburton et al, ACS Applied Materials and Interfaces, 8 (17), 11108–11121 (2016).
Poly Ionic Liquid Solid Electrolyte Interphase (SEI) Formation in an Improvement of 5V Class Lithium Ion Batteries
Authors: Wang Fu-Ming
Published: February 2020

Electric vehicles (EVs) are poised to dominate the next generation of transportation, but meeting the power requirements of EVs with lithium ion batteries is challenging because electrolytes containing LiPF6 and carbonates do not perform well at high temperatures and voltages. However, lithium benzimidazole salt is a promising electrolyte additive that can stabilize LiPF6 through a Lewis acid–base reaction [1]. The imidazole ring is not eligible for high-voltage applications owing to its resonance structure, but in this research, electron-withdrawing (−CF3) and electron-donating (−CH3) substitutions on imidazole rings were investigated. According to the calculation results, the CF3 substitution facilitates a high electron cloud density on imidazole ring structures to resist the electron releases from bezimidazole in oxidation reactions. In addition, through CF3 substitution, electrons are accepted from the lattice oxygen (O2−) in Lithium-rich (Li-Excess) layer material and O− is converted by electron to a great quantity, which catalyzes the electrolyte reduction and forms a new polyionic liquid solid electrolyte interphase on the cathode’s surface. Furthermore, the cycle performance tested at 60 °C and 4.8 V showed that the CF3 substitution maintains the battery retention effectively and exhibits almost no fading compared with both the blank electrolyte and the CH3 substitution. In addition, the results of this study confirm that bezimidazole salt greatly catalyzed the reduction of EC to a stage II reaction, and therefore less Li2CO3 formation was found. A possible reaction mechanism is shown in Figure 1.

Figure 1
Flexible High Performance Lithium Ion Battery Electrode Based on Free-Standing TiO2 Nanocrystals/Carbon Cloth Composite
Authors: Tjandra Ricky , Li Ge , Wang Xiaolei , Yan Ji , Li Matthew , Yu Aiping
Published: February 2020

Wearable and flexible electronics is an emerging and popular area of research. However, the availability of flexible energy storage to accompany these devices is lacking. Herein, a flexible electrode based on a composite of TiO2 nanocrystals and carbon cloth was synthesized by a simple drop-casting method followed a post-annealing treatment. The obtained TiO2/carbon cloth electrode shows a reversible capacity of 280-310 mAh g-1 at a current density of 100 mA g-1. The composite electrode also exhibits excellent mechanical stability even after 100 cycles of flexion. A proof-of-concept flexible pouch half-cell was assembled and it was able to power an LED bulb under flexion.
Synthesis of Li4Ti5O12 Microspheres and Their Electrochemical Performance As Anode Materials for Li-Ion Batteries
Authors: Park In-Su , Hong Hye-Jin , Kim Jiwoong , Ryu Taegong
Published: February 2020

Lithium titanate, Li4Ti5O12 (LTO) has drawn significant attention in the lithium ion battery because it shows some interesting features such as a low toxicity and low volume change (2-3%) on both lithium insertion and de-insertion, along with an excellent cycling life. Especially, the mesoporous LTO microspheres are considered as an ideal anode material because of their good rate performance, morphological properties, and a large tap density. However, it is very challenging to synthesize monodispersed LTO microspheres with desirable structural characteristics and electrochemical performances. In this study, LTO microspheres were synthesized using a facile process and cheap Ti-source (TiOSO4). The round shaped secondary particles (μm scale) were consisted of LTO primary particles (< 100 nm). The structural properties and electrochemical performances of Li4Ti5O12 microspheres will be discussed in the Meeting.

References

[1] Goriparti, S.; Miele, E.; De Angelis, F.; Di Fabrizio, E.; Proietti Zaccaria, R.; Capiglia, C. J. Power Sources,
2014, 257, 421.

[2] Lin, C.; Fan, X.; Xin, Y.; Cheng, F.; Lai, M.O.; Zhou, H.; Lu, L. Nanoscale, 2014, 6, 6651.

Figure 1. FE-SEM images of the synthesized microspheres.

Figure 1
In-Operando EDXRD of Graphite and Silicon-Graphite Electrodes in Lithium-Ion Cells
Authors: Yao Koffi P.C. , Kalaga Kaushik , Okasinski John , Almer Jon , Abraham Daniel P
Published: February 2020

Improvements in the energy density of lithium-ion batteries (LIBs), through the adoption of novel high capacity anodes as alternatives to graphite, are being widely pursued. Silicon, with a theoretical capacity of 3579 mAh g-1, lithiation voltage comparable to that of graphite, and high abundance, is considered the most appropriate alternative. The advantages of high energy density are countered by severe capacity fade, limiting the cycle life of Si-containing cells. Fundamental mechanistic understanding of lithiation and de-lithiation processes in Si-electrodes is essential to identify causes of capacity loss. Several in-situ and ex-situ microscopy and spectroscopy techniques have provided information on structural, chemical, and morphological changes of electrodes at specific states of charge and during calendar/cycle life ageing.

We adopted Energy Dispersive X-ray diffraction (EDXRD) to track structural changes in all components of pure Graphite (Gr) and Silicon/Graphite (Si/Gr = 15/73 w/w) based lithium-ion cells. Beamline 6 A-B at the Argonne Photon Source (APS), equipped with a fixed 3º angle single element Ge detector and incident white X-ray beam was used to obtain in operando EDXRD spectra from CR2032-type coin cells. The coin cells were assembled with a Li metal counter electrode, and 1.2 M LiPF6 in EC/EMC (3:7 w/w) + 10 wt% FEC as the electrolyte, and underwent electrochemical cycling at a ~C/8 rate. Lattice parameters corresponding to the spectral peaks were derived from the energy of the diffracted X-rays. Variations in the average Gr layer spacing during lithiation of the pure Gr half-cell was used to calibrate an “average layer spacing vs. state of lithiation” in the Gr-component. The lattice parameters of different phases formed upon lithiation and delithiation of Si and graphite were estimated which can, thus, be used to obtain the extent of lithiation in Si and in graphite quantitatively at every state-of-charge. The consequences of this lithiation-delithiation behavior will be highlighted during our presentation.

Acknowledgement:

The authors acknowledge colleagues at Argonne, especially S. Trask, B. Polzin, A. Jansen, and D. Dees. The electrodes and electrolytes are from Argonne’s Cell Analysis, Modeling and Prototyping (CAMP) Facility, which is supported within the core funding of the Applied Battery Research (ABR) for Transportation Program. Support from the U.S. Department of Energy’s Vehicle Technologies Program (DOE-VTP), specifically from Peter Faguy, is gratefully acknowledged. This document has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
High Safety Electrode Additive for Preventing Internal Short Circuit Problem in Lithium Ion Battery
Authors: Yeh Nan-Hung , Wang Fu-Ming
Published: February 2020

In January 2017, Samsung announced the reason why the Note 7 explodes and losses of more than 5 billion US dollar. According to their explanations, it was caused by the internal short circuit problem in the lithium ion battery. Currently, there is no effectively solution for eliminating the internal short circuit problem owing to the sudden accident.

In this research, a new technology has been developed, which can be used to terminate the thermal runaway and promise the safety performance of lithium ion battery. High voltage layer-type cathode material LLNNO (Li1.2Ni0.2Mn0.6O2) is employed and combined with this safety electrode additive for investigation. In terms of the results, Fig. 1 shows that the electrode additive significantly enhances the cycle performance at 60oC. In addition, the first charge and discharge curve shows in Fig. 2 that the power density is increased by the safety additive, indicating the Li+ diffusion pathway is well established on the electrode’s surface. This electrode additive not only provides high thermal stability on electrochemical reaction, but the columbic efficiency of charge-discharge is also enhanced.

Figure 1
Surface Modification of 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2 with SnO2 Cathode Material for Lithium Ion Batteries
Authors: Luo Hongze , Fikeni Lusanda , Manquthu Sinethemba Patricia , Seteni Bonani , Rapulenyane Nomasonto , Mathe Mkhulu K. , Wen Lei
Published: February 2020

Lithium and manganese-rich xLi2MnO3·(1−x)LiMO2 (M=Ni, Co, Mn) composite cathode materials are one of the most investigated cathode materials due to their ability to provide high discharge capacity. However, xLi2MnO3·(1−x)LiMO2cathode materials suffer from high initial irreversible capacity and poor cycling stability. The development of this type composite cathode materials for lithium ion battery is still the challenge for meeting current and future energy storage requirements.

The surface modification of the materials is an effective way to overcome those disadvantages according to many work have been reported. In this work, we report that the discharge capacity and cycle performance of 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2  was significantly improved though SnO2 surface modification. The X-ray diffraction study confirms that the material has layered LiMn0.5Ni0.5O2 structure along with the formation of the superlattice ordering of Li2MnO3 without any major change in the crystal structure with SnO2 surface modification. The lower resistance to charge transfer in the SnO2 modified sample is responsible for its better performance.
Ionically Enhanced SixFey/Li1.3Al0.3Ti1.7(PO4)3 Nanocomposite for High Performance Lithium-Ion Batteries
Authors: Cho Jong-Soo , Letfullina Alla R , Alaboina Pankaj Kumar , Uddin Md-Jamal , Cho Sung-Jin
Published: February 2020

Silicon (Si) is one of the most promising anode materials with the potential to meet the increasing demands of high energy and power for the next generation lithium-ion batteries. However, Si-based anodes suffer from huge capacity fading limiting their use in commercial applications. As one of root cause, it is known that Li+ ion diﬀusion is dramatically hindered leading to a strongly heterogeneous lithiation of the electrode and a rapid capacity fading after long term cycling. To break through the issue, we propose the SixFey/Li1.3Al0.3Ti1.7(PO4)3 (SFLATP) Nanocomposite. In this study, we synthesized SFLATP Nanocomposite with high energy planetary ball milling. The SFLATP nanocomposite exhibited excellent cycle life, rate capability and coulombic efﬁciency demonstrating its potential to be readily transformable to commercial applications.

Figure 1
Highly Engineered Si Alloy Flexible Battery
Authors: Alaboina Pankaj Kumar , Letfullina Alla R , Uddin Md-Jamal , Cho Jong-Soo , Puvvada Sudhakar , Cho Sung-Jin
Published: February 2020

Flexible, portable electronics and wearable devices are on emergence in the market and are anticipated to be the next generation of electronics advancement. To embrace the device flexibility requirement, the demand for high energy density flexible batteries itself are heavily considered. In this work, structurally controlled and highly engineered Silicon-Iron metal alloy (Si Alloy) was designed as the core chemistry materials for high energy and cycle life, and hosted on flexible substrates to support bending without mechanical degradations. This design integration into a pouch cell confirmed excellent flexible anode properties delivering significantly high capacity and stable cycle life. The battery pouch was bend to ~1.7 cm radius position and over, and was still able to to easily light up different Light-Emitting Diodes (LEDs) ranging from 2 V (Red LED) – 3 V (Blue LED) showcasing its flexibility and bendability features. The results spectacle an enormous potential for high energy ultrathin flexible batteries design and project the capability of great technical innovation.

Figure 1
The Effect of Tailoring Morphology of Ni-Rich Cathode Oxides on Electrochemical Stability for Lithium Ion Batteries
Authors: Gim Jihyeon , Yonemoto Bryan T , Gao Han , Liu Jianzhao , Ma Tianyuan , Xu Gui-Liang , Amine Khalil , Chen Zonghai
Published: February 2020

Understanding the correlation between physical and electrochemical/chemical properties are significantly crucial for development of electrode materials for lithium ion batteries. Among the materials, Ni-rich cathode materials with high energy density has degradation issue of electrochemical performance due to the parasitic reaction at the cathode electrolyte interface. The core-shell or concentration gradient materials consisting of a high-Ni core and a relatively high-Mn outer layer might be potential candidate providing improved stability as well as cycle life performance. In this respect, the porosity of final sintered particle can be an indicator to affect the electrode stability. The strategy to tune the particle porosity is introduced by controlling a feed rate of reactants during co-precipitation synthesis. The structural characteristics was compared for the materials obtained by different feed rate X-ray diffraction, electron microscopy, electrochemical performances, particle size distribution and porosity. The interfacial kinetic reaction between the Ni-rich cathode and a nonaqueous electrolyte at different SOCs is investigated by our home-built high-precision leakage current measurement system. This study can be an indicator for the safety of Ni-rich cathode by co-precipitation.
Lithium Molybdenum Oxyfluorides As High-Capacity Positive Electrodes for Rechargeable Lithium Batteries
Authors: Takeda Nanami , Hoshino Satoshi , Ikeuchi Issei , Natsui Ryuichi , Nakura Kensuke , Yabuuchi Naoaki
Published: February 2020

The demand for the increase in energy density of rechargeable lithium batteries are still growing. Recently, the use of two-electron redox of vanadium ions coupled with a high electronegativity anion in the crystal lattice is proposed as an effective strategy to enhance the energy density of positive electrode materials.[1] Theoretical capacities of lithium insertion materials depend on both total extractable lithium ions and electron numbers in the structure of positive electrodes. Therefore, in addition to the lithium-enrichment in the structure, the use of multi-electron redox processes for transition metals is expected to be an important strategy to further increase energy density of positive electrode materials. We have recently proposed a new lithium-excess oxide, Li9/7Nb2/7Mo3/7O2, which delivers a large reversible capacity of ca. 290 mAh g-1 based on highly reversible three-electron redox of Mo3+/Mo6+.[2] Three-electron redox of molybdenum ions is expected to be a promising system to further increase energy density of positive electrode materials with less transition metal ions. Nevertheless, redox potential of Mo3+/Mo6+in the oxide framework structure is relatively low for positive electrodes.

In this study, to increase in the redox potential of three-electron redox reaction of Mo3+/Mo6+, a mixed anion system, oxyfluorides, is targeted. Crystal structures and electrode performance of a new series of xLiF–LiMoO2 binary system, Li1+x
MoO2F
x
, as oxyfluoride positive electrodes are systematically examined. The highest theoretical capacity based on Mo3+/Mo6+ is expected for x = 2 (Li3MoO2F2) in this binary system. Li3MoO2F2 was prepared by mechanical milling from LiMoO2 and LiF. A mixture of LiMoO2 and LiF was mechanically milled with a ZrO2 container and balls. Li3MoO2F2 is found to crystallize into an anion-/cation-disordered rocksalt structure with low crystallinity. Electrochemical properties of Li3MoO2F2 before and after mechanical milling are compared in Figure 1. The sample after mechanical milling delivers a large reversible capacity of ca. 280 mAh g-1, which nearly corresponds to that of theoretical capacity based on the two-electron redox reaction of Mo3+/Mo5+. However, higher average voltage for the molybdenum oxyfluoride is evidenced compared with those of oxides.[2]

From these results together with structural and electrochemical data of Li1+x
MoO2F
x
(x= 0.5, 1, and 1.5), we will discuss the feasibility of molybdenum oxyfluoride materials with multi-electron redox reactions as positive electrode materials for rechargeable lithium batteries.

References

[1] R. Chen et al., Adv. Energy Mater.,
5, 1401814 (2015).

[2] S. Hoshino, et al., and N. Yabuuchi, ACS Energy Letters, 2, 733 (2017).

Figure 1
Three-Dimensional Phase-Field Simulation of Mechano-Electrochemical Behavior in LiCoO2 and Solid Electrode
Authors: Suzuki Yushi , Tsuyuki Chisa , Yamanaka Akinori , Asari Yusuke , Iwasaki Tomio
Published: February 2020

The phase-field (PF) model has been extensively used as a powerful numerical methodology for simulating microstructure evolutions in various materials. This study develops a three-dimensional PF model to simulate the lithium (Li) diffusion and the stress evolution in the positive electrode of the all-solid-state Li-ion battery which consists of LiCoO2 (LCO) particles and a solid electrolyte. The PF model incorporates the Cahn-Hilliard equation which describes the Li diffusion and the Butler-Volmer equation to determine the Li-ion flux at the interface between LCO and the electrolyte. In order to calculate the stress evolutions in LCO particles and the solid electrolyte at a low computational cost, we employ the PF microelasticity theory for elastically inhomogeneous systems that employs the Fourier transform to solve the mechanical equilibrium equation and, therefore, is more computationally efficient than the finite element method. Using the PF model, the effect of the Li concentration-dependent elastic constants of LCO on the stress evolution in a LCO particle during charging and discharging processes was revealed.
Surface-Modified Li4Ti5O12 for High Stability and Rate Performance Anode Materials
Authors: Yang Guijun , Kang Ji Hoon , Kang Jin Kyeong , Park Jong Won , Jung Yongju
Published: February 2020

Lithium titanium oxides have attracted great attention worldwide for use in long-life applications such as electric vehicles and energy storage systems. Because Li4Ti5O12 (LTO) operates at a higher voltage range (~1.5 V vs. Li/Li+) and experiences little volume change, excellent structural stability and safety are ensured during cycling without the formation of Li dendrites. However, it is well known that LTO materials have a drawback in rate property due to their poor electric conductivity, which has limited their practical applications to long-life lithium batteries until now [1].

So far, various approaches have been presented to overcome this issue, including different metal ion doping [2], surface treatment with conductive materials [3], synthesis of nanomaterials [4], and partial reduction of surface Ti4+ to Ti3+ by hydrogen [5]. However, most of methods are considered complicated and expensive processes in the aspect of a large scale production.

In this work, we fabricate various Li4Ti5O12 materials with different Ti3+ content through a carbothermal reduction process and intensively investigate the effect of Ti3+ on their electrochemical performances. In addition, we suggest an optimal surface composition of Li4Ti5O12 materials enabling high current operation as well as high capacity.

References

1. T. Ohzuku, A. Ueda, N. Yamamoto, J. Electrochem. Soc., 142, 1431 (1995).

2. D. Dambournet, I. Belharouak, J.W. Ma, K. Aminev, J. Power sources, 196, 2871 (2011).

3. G.N. Zhu, H.J. Liu, J.H. Zhuang, C.X. Wang, Y.G. Wang, Y.Y. Xia, Energ environ sci., 4, 4016 (2011).

4. Y.G. Wang, H.Q. Li, P. He, E. Hosono, H.S. Zhou, Nanoscale, 2, 1294 (2010).

5. J.X. Qiu, C. Lai, E. Gray, S. Li, S.Y. Qiu, E. Strounina, C.H. Sun, H.J. Zhao, A.Q. Zhang, J. Mater. Chem. A, 2, 6353 (2014).
Flexible, Three-Dimensional Ordered Macroporous TiO2 Electrode with Enhanced Electrode–Electrolyte Interaction in High-Power Li-Ion Batteries
Authors: Lui Gregory , Li Ge , Wang Xiaolei , Jiang Gaopeng , Lin Edric , Fowler Michael , Yu Aiping , Chen Zhongwei
Published: February 2020

A simple methodology is developed for the in-situ preparation of flexible, three-dimensional ordered macroporous (3DOM) TiO₂ electrodes with greatly enhanced mass transfer. The 3DOM electrode is fabricated using a polystyrene colloidal crystal templated carbon cloth, and provides significant improvements over conventional nanoparticle electrodes without the use of binder or other additive. When evaluated as an anode in a Li-ion battery, the 3DOM electrode provides outstanding high rate performance. The electrode provides a specific capacity of 174 mAh g-1 at a current density of 2 A g-1, which is 2.6 times greater than that achieved with a nanoparticle electrode (68 mAh g-1). The 3DOM electrode also achieves excellent cycling stability, with a capacity retention of 94.8% (181 mAh g-1) over 1000 cycles at 10C (1.7 A g-1) compared to 93.7% (67 mAh g-1) for the nanoparticle electrode. To the best of our knowledge, the performance of our 3DOM electrode is among the highest of binder-free, flexible TiO₂ electrodes. We believe that this methodology is highly useful and is easily transferable to other materials and applications.
A Prognostic and Filtering Analysis Technique for Estimating Battery Remaining Useful Life
Authors: Morris Larry , Weatherspoon Mark H
Published: February 2020

Evaluating the life expectance of a lithium-ion battery is critical for cost analysis in small portable device development to large sustainable electric energy systems. Estimation of the serviceability of the battery/battery pack ensures users are effectively replacing legacy components with new ones at the most opportunistic moments, ensuring critical systems failure does not occur and that the essential functions are fully operational/supported. Prediction models have been developed to assist with the maintenance/upkeep of these devices.

Capacity fade modeling is capable of detecting the effects of the growth in the solid electrolyte interphase (SEI) layer through cycling within the battery cell. Capacity fade modeling techniques are helpful with identifying remaining useful life (RUL) and is a widely hailed techniques for battery prognostic. Miao developed an unscented particle filter capable of predicting RUL in [1] but didn’t take into account the effects of depth of discharge on the cyclability of the battery cell. Guo used cycling to monitor the loss of capacity and power fade for a battery in [2] but didn’t take into account the effects of temperature. Sustained usage at multiple temperatures can have an adverse effect on the nominal battery capacity during prolonged cycling. Development of a comprehensive RUL technique can be accomplished using filtering methods to simulate the behavior of a battery under the following criteria: temperature, multiple C-rate and depth of discharge (DoD).

RUL techniques used to estimate the serviceability of the battery cell define the capacity of the battery during all useable cycles compared to the capacity of a new cell multiplied by a degradation variable. The degradation variable is based on a Bayesian estimation process which considers temperature, C-rate, and DoD for multiple discharge scenarios. Fig 1 compares the filtering techniques supported by simulated data for multiple operating voltages at ambient temperature which enables better prognostics of the battery.

References:

[1] Miao, Q., et al. “Remaing Useful Life Prediction of Lithium-Ion Battey With Unscented Particle Filter Technique.” Microelctronics Reliability 53 (2013) pp 805-810.

[2] Guo, J., et al. “A Bayesian Approach for Li-Ion Battery Capacity Fade Modeling and Cycles to Failure Prognostics.” Journal of Power Sources 281 (2015) pp 173-184.

Figure 1
Triisopropoxyboroxine (TiPBx) As an Electrolyte Additive for 18650-Type Li-Ion Batteries
Authors: Haruna Hiroshi , Takahashi Shin , Terada Shouhei , Uemura Shin , Tanaka Yasutaka
Published: February 2020

Li-ion batteries are currently used in portable electronic and power tools, electric vehicles, and grid energy applications due to their high energy density. They have already been commercialized. However the development of higher power and capacity as well as longer life batteries becomes more pressing. One method to attain a longer life cells is to adopt electrolyte additives such as vinylene carbonate (VC) exhibiting the significant increase in lifetime [1].

Boron-based compounds have possibilities to develop advanced liquid electrolytes [2]. Xu and Angell discovered lithium bis(oxalate)borate (LiBOB), which furnished superior anodic stability up to 4.5V vs Li/Li+ [3]. The LiBOB also provided the other interactive properties for Li-ion batteries such as high stability at high temperature [4].

　In this report the effects of tri-isopropoxy-boroxine (TiPBx) as an electrolyte additive were evaluated with composition analysis. Thus 18650-type battery cells equipped with electrolytes (1.0 mol/L LiPF6 in ethylmethyl carbonate (EMC) and ethylene carbonate (EC)) with or without TiPBx were prepared and the charge-discharge tests were conducted. In fact the cell with TiPBx showed the long-life time as compared with no TiPBx where the decrease in discharged capacity was constricted. Therefore the electrolyte solutions were extracted from cycled cells and their solution compositions were detected by nuclear magnetic resonance (NMR) techniques so as to examine the impact of charge-discharge cycles and the presence of TiPBx. The electrolyte compositions analyses with 1H- and 13C-NMR indicated that composition transformations were observed after 1000 cycles without TiPBx. In particular the ester exchange reaction of EMC took place to form diethyl and dimethyl carbonates respectively. 2D HMQC NMR indicated that the ester exchange reaction of EC was also detected to afford linear polycarbonates. On the other hand, the electrolyte composition after 1000 cycles with TiPBx has almost been kept as compared with the initial composition since the ester exchange reactions were suppressed. These indicated that TiPBx prevented the ester exchange reactions giving rise to constricting the decrease in discharge capacity. We will discuss relations of the reaction mechanism of the electrolyte with the degradation of the battery performance.

[1] D. Aurbach, K. Gamolsky, B. Markovsky, Y. Gofer, M. Schmidt and U. Heider, Electrochimica Acta., 47, 1423 (2002).

[2] H.Horino, H. Tamada, A. Kishimoto, J.Kaneko, Y. Iriyama, Y. Tanaka and T. Fujinami, J. Electrochem., Soc., 157 (6) A677 (2010).

[3] K.Xu and C.A.Angell, Electrochem. Solid-State Lett., 4, E1 (2001).

[4] K. Amine, J.Liu, S.Kang, I.Belharouak, Y, Hyung, D. Vissers and G.Henriksen, J. Power Sources., 129, 14 (2004).
Non-Intercalating Phases and Electrochemical Behavior of Lithium-Ion Battery Cathode
Authors: Mistry Aashutosh , Mukherjee Partha P
Published: February 2020

Lithium-ion batteries are a promising choice for electric vehicles and grid storage, given the excellent cycle life and superior voltage response. A key thrust in current research efforts centers on improvement in energy and power density, which in turn is a strong function of the porous electrode microstructure. In particular, positive electrodes (cathode) can be limiting owing to poorer lithium storage capacity and inferior electronic conductivity. Consequently, positive electrode microstructures contain additional non-intercalating phases (such as, conductive additive and binder), which however have a bearing on the underlying transport mechanisms and ultimately on the electrochemical performance attributes. In this work, a hierarchical, mesoscale model has been developed to comprehend the implications of secondary phases on the cathode properties and cell performance. The cell response is quantified by rate capability, internal resistance, and electrochemical impedance response. The results reveal a highly non-linear dependence on the secondary phase characteristics and emphasize the significance of transport-electrochemical coupling.
Coupled Mechano-Electrochemical Interaction in Silicon Anode with Solid Electrolyte Interphase Layer
Authors: Verma Ankit , Mukherjee Partha P.
Published: February 2020

Silicon is an attractive candidate as a negative electrode material for lithium-ion batteries due to its high theoretical capacity (4200 mAh/g). However, high volume change (nearly 300%) in Si during lithiation and delithiation has significant deleterious effects, causing particle fracture beyond a critical size of around 200-300 nm even for low C-rates. The limitations of Si anodes are compounded by the fact that the prohibitively high expansion precludes the formation of a stable solid electrolyte interphase (SEI) layer. The SEI side reactions continue unabated with Si unlike graphite where the SEI film stabilizes after the first few cycles forming a protective layer between the electrode and the electrolyte. Consequently, capacity-fade with the Si anode progresses fast leading to low cycle life. In this regard, it is necessary to delineate the effect of coupled mechanical and chemical degradation modes in Si active particles along with SEI layer. In this work, we focus on investigating the coupled mechano-electrochemical interaction, based on a stochastic modeling and analysis, in Si active particles with SEI layer, as shown representatively in the attached figure including fracture evolution and damage stochastics phase map.

Figure 1
Exploration of Electrolytes for High Voltage Substituted Lithium Cobalt Phosphate Cathode Materia
Authors: Delp Samuel A. , Allen Jan L. , Jow T Richard
Published: February 2020

Next generation lithium ion batteries need higher energy density to displace the current technology, which operate around 4 V. Higher energy density can be achieved by increasing the specific capacity and/or the working voltage of the cathode active material. One such possibility is LiCoPO4 (LCP) which theoretically delivers 167 mAh g-1 at 4.8 V. Unfortunately, LCP undergoes rapid capacity fading in its pure form. The introduction of small quantities of dopants to create a substituted-LCP has greatly increased the cycle life over pure LCP [1].

With the development of new high voltage cathode materials such as LCP comes the need for electrolytes that will enable their implementation. Current state of the art (SOA) LiPF6/carbonate based electrolytes are only stable up to ~4.5 V. Two strategies used to increase the electrochemical window of electrolytes include using different solvents such as fluorinated solvents that are stable to higher voltages or using sacrificial additives that undergo reduction/oxidation reactions before the bulk electrolyte does. The latter approach was explored in a recent study using 4.7 V LiNi0.5Mn1.5O4 (LNMO) spinel [2]. Vinylene carbonate (VC), a common additive for SEI formation, did not work with LNMO/graphite cells due to the fact that VC oxidizes at a much lower potential than the bulk electrolyte but at a higher potential than SOA cathode materials (>4.2 V) as shown by cyclic voltammetry on glassy carbon electrodes. The oxidation of VC at the cathode prevents its incorporation into the anode SEI layer. Another additive, tris(trimethylsilyl) phosphate showed a similar reduction behavior to VC but was more oxidatively stable. This showed the importance of not only the oxidation stability but also the reduction stability that are both necessary for future electrolytes. The oxidation and reduction stabilities of electrolytes with different additives and combinations of additives using LCP cathode material will be reported.

References

[1] J. L. Allen, J. L. Allen, T. Thompson, S. A. Delp, J. Wolfenstine, T. R. Jow, J. Power Sources, 327, 229 (2016).

[2] S. A. Delp, O. Borodin, M. Olguin, C. G. Eisner, J. L. Allen, T. R. Jow, Electrochimica Acta, 209, 498 (2016).
Ab-Initio Study of Li-Ion Electrolyte Li2(OH)Cl
Authors: Howard Jason David , Hood Zachary D. , Holzwarth Natalie A. W.
Published: February 2020

The material Li2(OH)Cl is experimentally found to exist in two phases, a poor Li-ion conducting orthorhombic phase (T<312K) and a fast Li-ion conducting disordered cubic phase (T>312K). Recently experiments report the high temperature phase cycled in a symmetric cell with lithium electrodes with the apparent creation of a stabilizing solid electrolyte interphase layer[1]. Li2(OH)Cl is related to a variety of other materials that have been studied for their Li-ion electrolyte properties, Li2+x(OH1-x)Cl, Li2(OH)Br, and Li2(OH)1-xFxCl.[2][3]

We report the results of a combined computational and experimental study of the structural and ion migration properties of this material as a function of temperature. Using first principles methods to calculate the idealized static structures together with estimations of the phonon free energies in the quasi-harmonic approximation, the simulations predict several phases at low temperature including tetragonal and orthorhombic structures. The predicted orthorhombic phases are similar to experimental X-ray analysis performed at temperatures 15 K < T < 300 K as well as with literature reports,[1][2] while the tetragonal phase may be difficult to experimentally realize. Additionally, the disordered cubic phase was investigated using first-principles molecular dynamics to determine the lithium tracer diffusion and several order parameters in the temperature range of ~350-650 K.

[1] Hood, Z. D., Wang, H., Pandian , A. S., Keum, J. K. and Liang, C. J. Am. Chem. Soc. 138 1768-1771 (2016).

[2] Schwering G., Hönnerscheid, A., van Wüllen, L., and Jansen, M.,
CHEMPHYSCHEM, 4, 343-348 (2003).

[3] Li, Y., Zhou, W., Xin, S., Li, S., Zhu, J., Lü, X., Cui, Z., Jia, Q., Zhou, J., Zhao, Y., Goodenough, J.B.,. Angewandte Chemie International Edition, 9965–9968 (2016).

Acknowledgements:

Jason Howard was supported by NSF grant DMR-1507942. Computations were performed on

the Wake Forest University DEAC cluster, a centrally managed resource with support provided in part by the University. A portion of this research was supported by the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, which is a U.S. Department of Energy (DOE) Office of Science User Facility. Zachary Hood was supported by a Graduate Research Fellowship award from the National Science Foundation (DGE-1148903) and the Georgia Tech-ORNL Fellowship.