bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Silicon Expansion upon Lithiation on Electrode and Cell Thickness
Authors: Jansen Andrew N. , Trask Stephen E , Polzin Bryant J 
Published: February 2020

The constant demand for more energy in smaller volumes requires the need for high energy density cathodes and anodes. While there exists a portfolio of available cathode materials with increasing incremental improvements in energy, the choices on the anode side of the cell have been limited to graphite and hard carbon. In recent years, attention has been directed to improving the graphite energy density by adding silicon. However, the volume expansion of a silicon particle can approach 400% upon full lithiation. This large expansion and contraction of the silicon particle during electrochemical cycling not only has a negative influence on the robustness of the solid electrolyte interface (SEI) layer, but also negatively impacts the dimensional tolerance of the electrode, cell, and battery.
In this work, the variation of the electrodes and cell thickness is measured for a baseline graphite and several silicon-graphite/graphene electrode systems. These values were determined before cycling, after formation, and at various states of charge by measuring the entire cell thickness change and the electrodes themselves after disassembly. For this study, xx3450 (format size) single-sided single-layered pouch cells were used with ~20 mAh capacity, and 1.2 M LiPF6 in EC:EMC (3:7 wt.%) + 10 wt.% FEC was used as the electrolyte. These cells were made and tested in Argonne’s Cell Analysis, Modeling, and Prototyping (CAMP) Facility.
Figure 1 is a summary of the percent change in thickness for the anode only relative to the initial dry electrode for the baseline graphite anode and three classes of silicon-based anodes still in development. The silicon-based anodes in general have a higher percent rise in thickness than graphite alone, but with proper particle composition and morphology the impact on electrode thickness can be controlled to an acceptable level. In these cells, the cathode (and separator) changes were relatively insignificant.
The impact of anode expansion on the total cell thickness was estimated for various anode-cathode pairings. With proper electrode design, it was found that the variation in cell thickness during charge and discharge could be held within 10% for the three classes of silicon-based anodes studied in this work, provided the silicon content was the minor constituent. While accounting for the thickness changes in anode systems is an important feature to monitor when using silicon-based materials, more work is still needed to enhance their cycle life.
Support from David Howell and Peter Faguy of the U.S. Department of Energy’s Office of Vehicle Technologies is gratefully acknowledged. This work was performed under the auspices of the US Department of Energy, Office of Vehicle Technologies, Hybrid and Electric Systems, under Contract No. DE-AC02-06CH11357

Figure 1
Li1.14Mn0.53Ni0.28Co0.19Oy layered-Layered Spinel Material Prepared Using Taylor Vortex Reactor
Authors: Kahvecioglu Feridun Ozgenur , Shin Youngho , Krumdick Gregory 
Published: February 2020

In this work, precursor for Li1.14Mn0.53Ni0.28Co0.19Oylayered-layered spinel cathode material was synthesized by carbonate co-precipitation method using a Taylor Vortex reactor. In a similar fashion, we also utilize a 20L continuous stirred tank reactor (CSTR) to produce and compare the cathode materials with same composition.
Recently, layered-layered spinel structures are explored to mitigate the voltage fade issue to some extent. Even though these materials deliver lower capacities than the Li- and Mn- rich (LMR-NMC) materials, they have the key feature of “spinel induced” structures which make the voltage fade relatively less compared to LMR-NMC materials.
Here, by adopting Taylor Vortex reactor, we demonstrate that the usage of Taylor Vortex Flow shows good advantages to produce highly crystalline, spherical and dense cathode precursors in a relatively short residence time compared to CSTR.
The particle size and distribution of the synthesized cathode powders are analyzed using particle size analyzer (PSA) and are confirmed with scanning electron microscopy (SEM). The composition and the phase determination of the cathode materials are characterized by inductively coupled plasma mass spectroscopy (ICP-MS) and X-ray diffraction (XRD). These cathode materials were electrochemically tested using Voltage Fade protocol of Argonne National Laboratory.
Investigations of Lithium-Sulfur Batteries at Low and High Temperatures
Authors: Cañas Natalia Andrea , Zhao Sijie , Wagner Norbert , Friedrich Kaspar Andreas 
Published: February 2020

The research of lithium-sulfur (Li-S) batteries keeps growing motivated by its high theoretical energy density (around 2600 Wh kg-1) and the continuous improvement on the cycling stability, like it has been gained in the last five years [1,2]. In situ and ex situ techniques have been already developed to get a deeper understanding on reaction mechanisms and degradation processes [1-5]. However, only few studies investigated the behavior at temperatures below and above ambient [6,7].
In this work, Li-S batteries were investigated in a temperature range between -15 °C and 75 °C. The cathode consisted of a simple carbon/sulfur composite and lithium foil was used as anode. Two electrolytes were investigated: 1 M Lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) in DOL:DME (1:1, v:v) with and without LiNO3. Electrochemical impedance spectroscopy was chosen as principal characterization technique to evaluate the influence of the temperature on the electrochemical and degradation processes. The resistance of electrolyte, charge transfer resistance in the electrodes, as well as the dissolution and precipitation of the end products (sulfur and lithium sulfide) were analyzed by modelling the experimental results with an equivalent electric circuit. Furthermore, the function of the already known electrolyte co-salt LiNO3 to avoid the shuttle mechanism was evaluated in a wide temperature range. The results show that the “protective” effect of LiNO3 is negatively influenced by extreme temperatures. Moreover, morphology and structural changes in the sulfur/carbon composite cathode were analyzed using ex situ scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively.
1. A. Manthiram, Y. Fu , S.-H. Chung , C. Zu , Y.-S. Su, Chem. Rev., 2014, Article ASAP, DOI: 10.1021/cr500062v
2. M.-K. Song, E. J. Cairns, and Y. Zhang, Nanoscale, 2013, 5, 2186–204.
3. N. A. Cañas, K. Hirose, B. Pascucci, N. Wagner, K. A. Friedrich, and R. Hiesgen, Electrochim. Acta, 2013, 97, 42–51.
4. N. A. Cañas, S. Wolf, N. Wagner, and K. A. Friedrich, J. Power Sources, 2013, 226, 313–319.
5. N. A. Cañas, D. N. Fronczek, N. Wagner, A. Latz, and K. A. Friedrich, J. Phys. Chem. C, 2014, 118, 12106–12114.
6. Y. V. Mikhaylik and J. R. Akridge, J. Electrochem. Soc., 2003, 150, A306.
7. X. He, W. Pu, J. Ren, L. Wang, J. Wang, C. Jiang, and C. Wan, Ionics, 2007, 14, 335–337.

Figure 1
N-Doping Effect for Polysulfide Reservoir within Mesoscale Electrodes for Practical Application of Lithium Sulfur Batteries
Authors: Chen Junzheng , Wu Dangxin , Walter Eric , Engelhard Mark H , Bhattacharya Priyanka , Pan Huilin , Shao Yuyan , Gao Fei , Xiao Jie , Liu Jun 
Published: February 2020

Lithium sulfur batteries have become one of the most promising energy storage technologies, potentially meeting the needs for vehicle electrification and stationary applications, because of its lower costs, environmental friendly property and much higher energy density (cathode theoretical energy: 3500 Wh/kg, or 2800 Wh/L) than that of state-of-art Li-ion batteries. However, many challenges exist for the broad deployment of Li/S system. The main challenge is the low Columbic efficiency and fast capacity decay due to the shuttle reactions caused by the soluble intermediate polysulfide
Nitrogen-doped porous carbon (NPC) and multi-wall carbon nanotube (MWCNT) have been frequently studied to immobilize sulfur in lithium-sulfur (Li-S) batteries. However, neither NPC nor MWCNT itself can effectively confine the soluble polysufides if cathode thickness e.g. sulfur loading is increased. In this work, NPC was combined with MWCNT to construct an integrated host structure to immobilize sulfur at a relevant scale. The function of doped nitrogen atoms was revisited and found to effectively attract sulfur radicals generated during the electrochemical process. The addition of MWCNT facilitated the uniform coating of sulfur nanocomposites to a practically usable thickness and homogenized the distribution of sulfur particles in the pristine electrodes, while NPC provided sufficient pore volume to trap dissolved species. More importantly, the wetting issue, the critical challenge for thick sulfur cathodes, is also mitigated after the adoption of MWCNT, leading to a high areal capacity of ca. 2.5 mAh/cm2 with capacity retention of 81.6% over 100 cycles. This work provides clues on the fundamental mechanism of N-doping and the strategies to practically develop nano-structured materials for battery applications.

Acknowledgment

This work was supported by the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The EPR, XPS, and SEM analyses were performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Department of Energy’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL).
SEI-Film-Suppression Additive for Enhancing Compatibility and Electrochemical Stability of Graphite Anode in PC-Based Electrolytes
Authors: Xiang Hongfa , Yan Pengfei , Bhattacharya Priyanka , Bowden Mark E , Cao Ruiguo , Qian Jiangfeng , Polzin Bryant J , Wang Chongmin , Zhang Ji-Guang , Xu Wu 
Published: February 2020

Lithium-ion batteries (LIBs) are one of the most promising power sources for electric vehicles because of their high energy density and long lifetime. Graphite is widely used as anode electrode material in the state-of-the-art LIBs. However, a graphite anode is usually only compatible with an ethylene carbonate (EC)-based electrolyte. When contacting with a propylene carbonate (PC)-based electrolyte, which is advantageous over the EC-based one for its wider temperature range and higher low-temperature conductivity, the graphite anode may suffer from substantial exfoliation problem during the initial lithium intercalation step. Consequently, a PC-based electrolyte cannot be used in LIBs with graphite as the anode unless some solid electrolyte interphase (SEI) film-formation additives are introduced into the electrolytes. Usually this type of additives is reduced predominantly on the graphite electrode surface before PC is intercalated and reduced. These additives mainly contain some functional groups such as vinylene or cyclic unsaturated compounds. For example, vinylene carbonate (VC) and fluoroethylene carbonate (FEC) have been widely studied and used as additives for PC-based electrolytes. They play an important role in the protection of the structure of the graphitic anode from destruction by PC, but they also have some shortcomings. Usually these additives result in a thick SEI protective layer, which could significantly reduce the rate capability and limit low-temperature performance and cycling stability at elevated temperatures because of its additional impedance and poor thermal stability.
Recently, we developed a novel electrolyte additive that can suppress the PC reductive decomposition on the graphite anode without a thick and resistant SEI film. The additive may provide a novel protective mechanism for the graphite anode in the PC-containing electrolytes without or with suppressed SEI film formation. The SEI-film-suppression additive can not only significantly improve the compatibility between graphite anode and PC-containing electrolyte, but also exhibit superior rate capability and excellent cycling stability at elevated temperatures.We believe that this new electrolyte additive can be applied to LIBs and other electrochemical systems using PC-containing electrolytes and graphite anodes. The details of the results will be reported.

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technology of the U.S. Department of Energy (DOE). The electron microscopy and XRD measurements were performed at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL.
(Invited) New Electrolyte Solvents and Additives Designed for Li Ion and Beyond Chemistries
Authors: Xu Kang , Zhang Zhengcheng , Abraham Daniel P , Amine Khalil , Cresce Arthur v. , Russell Selena M. , Borodin Oleg , Wang Chunsheng 
Published: February 2020

Ever since the birth of Li ion chemistry, carbonate esters have been the main solvents used as the skeleton composition of the electrolytes. This class of polar organic compounds, ethylene carbonate in particular, brings both their merits of supporting reversible intercalation of Li+ at electrodes of potential differences as wide as 4.2 V, and their intrinsic limits of narrow temperature range, chemical reactivity toward conducting salts, and inflammability. Numerous efforts were made during the past decades in an attempt to replace these carbonate, either partially or entirely, but little change has occurred as the result.
The emergence of new chemistries such as the high voltage (>4.5 V) cathode intercalation materials and the beyond-Li-ion concepts −− most of which resort to conversion-reaction concepts to maximize the specific capacities −− presents unprecedented challenges to these carbonate esters that have been widely used by Li-ion industry, and activities resumed in seeking new alternatives. This presentation will summarize our recent efforts of designing, synthesizing and characterizing such new electrolyte solvents in both high voltage and Li-ion as well as beyond-Li-ion chemistries.
Galactomannan-Bound Battery Electrodes for High-Performance Applications
Authors: Dufficy Martin K , Khan Saad A , Fedkiw Peter S 
Published: February 2020

Lithium-ion batteries are ubiquitous energy storage devices, yet expanding market needs require higher energy and power densities than presently available. Inexpensive materials with low-processing costs stimulate the exploration of novel battery materials. One possible solution to meet charge capacity demands is through the incorporation of silicon in anode materials. However, volume expansions during lithiation leads to fractured electrodes and binders, which leads to electronic isolation. Binding agents are a critical component in a battery and may also be used to enhance electrode performance. Herein, we report the use of galactomannans—an inexpensive, environmentally friendly, biorenewable polymer—as a novel binder for Si electrodes. Silicon-containing electrodes with as low as 5 wt.% binder exhibit large reversible capacities with > 90% charge retention after 100 cycles without use of electrolyte additives. Increased capacities allow for greater energy densities while lower binder content allows for fast Li-extraction for high-power applications (Figures 1a, b). The observed performance enhancement may be attributed to polymer-particle interactions between the hydroxyl groups of galactomannans and native-oxide layer of Si. The interactions, coupled with the inherent mechanical integrity of galactomannan thin films, allow for minimal electrode cracking and delamination upon lithiation. The undamaged electrode microstructure during large volume expansions (Figure 1c) allows for columbic efficiencies > 99% to be observed. Galactomannans also experience ample polymer swelling in common electrolyte solvents, which leads to rapid Li transport and lower resistivities than other biopolymer-bound electrodes. Galactomannan binders may thus provide a critical step forward in next-generation lithium-ion batteries.
Figure 1. (a) Charge/discharge profiles of guar gum-bound Si electrodes and (b) Li-extraction capacities using guar gum and locust bean gum as binders. Electrodes were lithiated at 0.05-C and delithiated at the specified C-rate. (c) The scanning electron microscope image shows the undamaged porous electrode structure of galactomannan-bound Si nanoparticles after 50 charge/discharge cycles of deep lithiation at 1-C.

Figure 1
Optimization of the Thermal Treatment of Electrospun Poly(acrylonitrile) for Flexible, Binderless, and Collectorless Lithium-Ion Carbon Nanofibers Anode
Authors: Beach Jeremy , Moore Robert B 
Published: February 2020

The processing of carbon nanofibers prepared by electrospinning poly(acrylonitrile) and subsequent thermal treatment has been optimized for use as a binderless, flexible, and collectorless anode for lithium ion batteries. Previous literature has failed to report, and in some instances account for, all aspects of processing as they relate to specific capacity in a comprehensive and systematic study. Solutions of 12 wt% poly(acrylonitrile) in DMF were used throughout and were electrospun and thermally treated using various approaches. The highest specific capacity obtained after 10 cycles at a current of 100 mA/g was greater than 550 mAh/g and exhibited Coulombic efficiencies of < 98% after the first cycle. This specific capacity is <30% higher than previously reported anodes cycled at half of the reported current (50 mA/g) and almost 200 mAh/g higher than the theoretical capacity of pure graphite (372 mAh/g). Flexible carbon nanofibers prepared by this scalable method have been shown to be a viable binderless and collectorless lithium ion anode material. Applying these concepts to carbon nano-composite anodes previously reported in literature would further enhance their energy and power densities.
Redox-Active Functionalized Graphene Nanoribbons As Electrode Material for Li-Ion Batteries
Authors: Pirnat Klemen , Bitenc Jan , Jerman Ivan , Dominko Robert , Genorio Bostjan 
Published: February 2020

Current Li-ion systems still require substantial optimization in terms of realizing a more favorable price-to-performance ratio, especially in the renewable energy storage sector. To achieve this, several new materials and approaches are currently being tested and developed and, in particular, great promises and expectations lie in the graphene-based materials. Graphene is a stable 2D honeycomb-structured carbon material with extraordinary mechanical, optical, thermal and electrical properties.1 On the other hand redox-active organic materials offer high theoretical capacities; however, most organic materials show drastic capacity fading during cycling, mainly caused by the dissolution of the active materials in organic electrolytes. In this work, we combined extraordinary properties of graphene with high capacity of organic compounds to get electrochemically stable composite material. Graphene nanoribbons (GNRs) were grafted with electroactive molecules, where functionalized GNRs serve as a current collector, binder, and active material at the same time. GNRs were prepared by unzipping commercially available multi-walled carbon nanotubes with a Na/K alloy and in-situ functionalized with different hydroquinone derivatives. All synthesized materials were electrochemically characterized in Li-ion battery cells. The physical characteristics of the synthesized materials were determined by using evolved-gas analysis, Raman spectroscopy, and scanning electron microscopy. These analyses show the successful functionalization of GNRs and improved electrochemical performance compared to non-functionalized GNRs.2

(1) Rao, C.; Sood, A. Graphene: Synthesis, Properties, and Phenomena; Rao, C. N. R.; Sood, A. K., Eds.; 1st ed.; Wiley-VCH Verlag GmbH & Co. KGaA: Weinheim, 2013; p. 400.
(2) Pirnat, K.; Bitenc, J.; Jerman, I.; Dominko, R.; Genorio, B. Redox-Active Functionalized Graphene Nanoribbons as Electrode Material for Li-Ion Batteries. ChemElectroChem
2014, n/a–n/a.

Figure 1
Insight for Formation of Oxygen Deficiency in Spinel-Type LiNi0.5Mn1.5O4-δ
Using Ab Initio DFT Calculations
Authors: Shiiba Hiromasa , Zettsu Nobuyuki , Nakayama Masanobu , Oishi Shuji , Teshima Katsuya 
Published: February 2020

Spinel-type LiNi0.5Mn1.5O4 (LNMO) have attracted attention as cathode materials for lithium-ion batteries due to its high-voltage at ~ 4.7 V vs. Li+/Li. LNMO is considered to belong to two different crystal structures such that Ni/Mn ordered P4332 and disordered Fd-3m. Relationship between crystal structures and their electrochemical performances has been experimentally- and computationally- investigated, showing that disordered Fd-3m structure contains oxygen deficiency with reduction of Mn from Mn4+ to Mn3+. Although the presence of Mn3+ improve electronic conductivity, Jahn-Teller distortion and dissolution of Mn occurs. Phase transition from disordered Fd-3m to ordered P4332 occurs with diminish oxygen deficiency by annealing in oxygen atmosphere at 700 ̊C. Understanding the formation mechanism of the oxygen deficiency would be helpful to synthesis aimed crystal structure. However, computational studies with oxygen deficient model are limited so far. In this study, we evaluate the defect formation energies in oxygen deficient LNMO.
The Vienna ab initio simulation package (VASP) was utilized with the generalized gradient approximation (GGA-PBEsol) + U and projector-augmented wave (PAW) methods. For the GGA + U calculations, the U values for the d-orbitals of Ni and Mn were set to 6.0 eV and 3.9 eV following relevant previous reports. An energy cutoff of 500 eV and a k-point mesh were chosen such that the product of the number of k-points and the number of atoms in the unit cell was greater than 1000.
In the case of disordered Fd-3m structure, we used ‘uniform’ Ni/Mn distribution computationally reported by Lee et al., that is, the highest degree of local cation arrangements within random cation ordering. Coulombic energy was calculated for different 524 structures by Ewald method, the most stable Ni/Mn arrangement was consistent with ‘uniform’ distribution as mentioned above.
The calculated lowest oxygen vacancy formation energies in P4332 and Fd-3m show 3.69 eV and 3.38 eV, respectively. Note that vacancy formation energy almost no difference in P4332 among different oxygen vacancy concentrations, whereas, in Fd-3m, vacancy formation energy decreased with increasing oxygen vacancy concentrations. This fact strongly suggests that Fd-3m structure promotes oxygen deficiency. In addition, not only oxygen vacancies type defect but also metal-excess type defect can be present as oxygen defect models. Formation energies for the system contains excess metals in P4332 and Fd-3m lattice show 2.98 eV and 2.58 eV, respectively. Formation energy for metal excess type in Fd-3m became 0.40 eV smaller than that in P4332, in agreement with experimental results that only Fd-3m contains oxygen defects. In addition, these values are lower than oxygen vacancy formation energies. These all finding indicates that metal-excess type oxygen deficiency can be more favorable than oxygen vacancy type oxygen deficiency for LNMO.