bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lithium Overpotential and Dendrite Formation
Authors: Heine Jennifer , Bieker Peter , Winter Martin 
Published: February 2020

Lithium metal has a higher theoretical capacity compared to graphite, which is the most commonly used anode material in a lithium ion battery (LIB).[1] Nevertheless, secondary lithium metal batteries have plenty of challenges to overcome, before they could replace the well established LIBs. One main challenge of these batteries is the lithium dendrite formation during cycling. In the presence of an appropriate organic electrolyte, lithium is kinetically stable against corrosion due to the formation of a solid electrolyte interphase (SEI).[2] If the SEI is locally different in morphology and composition, the current density distribution on the lithium electrode during charging can be inhomogeneous. This leads to an inhomogeneous lithium plating process and results in a needle-like deposition, which is frequently called dendritic lithium deposition.[3] Figure 1 depicts needle-like lithium deposition on the lithium electrode after cycling. During cycling, dendrites can grow from the anode to the cathode and can cause a short circuit or a thermal runaway.
Different types of lithium deposition morphologies are known: needle-like, mossy and granular lithium.[4-5] The needle-like lithium (Figure 1b), with its high surface area, has most detrimental impact on cycling and safety performance of lithium metal cells. A novel method to monitor the changes of the surface morphology during cycling is the continuous observation of the development of lithium overpotential during cycling (Figure 1a).
In this work, we will explain how the overpotential occurs and how the lithium overpotentials correlate with the change of the surface structure. Furthermore, it is demonstrated that by increasing the surface area of the lithium metal electrodes and, in parallel, using a highly concentrated electrolyte, the formation of dendritic lithium can be reduced.

References

[1] von Sacken, U.; Nodwell, E.; Sundher, A.; Dahn, J. R., J. Power Sources
1995,
54(2), 240-245.
[2] Winter, M., Zeitschrift für Physikalische Chemie
2009,
223(10-11), 1395-1406.
[3] Aurbach, D.; Zinigrad, E.; Cohen, Y.; Teller, H., Solid State Ionics
2002,
148(3–4), 405-416.
[4] Gireaud, L.; Grugeon, S.; Laruelle, S.; Yrieix, B.; Tarascon, J. M., Electrochem. Commun.
2006,
8(10), 1639-1649.
[5] Sano, H.; Sakaebe, H.; Matsumoto, H., J. Power Sources
2011,
196(16), 6663-6669.
Figure 1 a) Overpotential of lithium during cycling, b) needle-like dendrites.

Figure 1
3,7-Bis(trifluoromethyl)-N-Ethylphenothiazine: A Highly Soluble, Highly Stable Redox Shuttle and Electro-Active Material for Non-Aqueous Redox Flow Batteries
Authors: Odom Susan A , Ergun Selin , Elliott Corrine F , Kaur Aman Preet , Holubowitch Nick 
Published: February 2020

3,7-Bis(trifluoromethyl)-N-ethylphenothiazine (BCF3EPT) is one of several derivatives of phenothiazine prepared in our laboratory for evaluation as redox shuttles for overcharge protection in lithium-ion batteries. We varied alkyl substituents at the N position and incorporated electron-withdrawing substituents at the 3 and 7 positions. Derivatives with ethyl and iso-propyl groups at the N position were the most stable, and those with chloro and trifluoromethyl substituents were the most robust in overcharging lithium-ion batteries. BCF3EPT showed the highest rate performance when dissolved at 0.5 to 1.5 M in 1.2 M LiPF6 in EC/EMC in graphite/LFP coin cells. At 0.08 M BCF3EPT, batteries lasted over one year in overcharge at a charging rate of C/10. When compared to dimoethoxybenzene-based redox shuttles, the radical cation of BCF3EPT – generated by chemical oxidation with tris(2,4-dibromophenyl)aminium hexachloroantimonate – was more stable in battery electrolyte. The stability of the radical cation form of redox shuttles is critical to overcharge protection and limited effects of the redox shuttle on SEI formation, so the stability of the radical cation of BCF3EPT may explain its extended performance in side-by-side overcharging experiments. In addition to overcharge protection studies, we also studied BCF3EPT as an electron-donating electro-active material in non-aqueous redox flow batteries including one example in which BCF3EPT and trimethylquinoxilane (TMeQ) were incorporated into 1 M LiBF4 in PC and tested in a stationary coin cell following a setup used by Brushett’s group, testing concentrations up to 0.4 M of both species, the anolyte being the limiting factor in high concentration batteries. Lastly, we have focused on the scale-up of BCF3EPT, which we prepare in three steps from commercially available phenothiazine. So far the first and second transformations have yields of more than 95%, and the last step - the trifluoromethylation – can be conducted in over 90% yield.

Figure 1
Hollow Carbon Nanosphere/Germanium Nanoparticle Composite Li-Ion Anode
Authors: Banek Nathan A , Hays Kevin Alan , Wagner Michael J 
Published: February 2020

Since their introduction, lithium ion batteries have become ubiquitous for powering portable electronic devices. However, the charging rate of graphite (by far the most common anode material) is relatively slow due to long lithium diffusion pathlengths. Highly graphitic hollow carbon nanospheres (HCNS) have a tremendous advantage over micron-sized graphite particles as the diffusion path length is on the nanoscale, 3 orders of magnitude shorter than graphite’s, facilitating rapid charging within a few minutes, rather than many hours. In addition, HCNS anodes cycle stably in inexpensive low melting point electrolytes, cycling with excellent capacity retention and high rate at temperatures as low as -50 ˚C. Unfortunately, HCNS anodes have lower specific capacity compared to those made with graphite (~220 mAh/g vs. 372 mAh/g).(1) However, the high surface area, good electrical conductivity and excellent electrochemical stability of HCNS make it a promising support material for other high capacity lithium alloying materials, suggesting the possibility of significantly higher specific capacities, much better low temperature performance and charging rates than graphite-based anodes. Here we present our studies to date on the incorporation of germanium metal, second only to Si in gravimetric capacity as a Li alloying material (1385 mAh/g) and nearly equal to it in volumetric capacity (7372 mAh/mL), into HCNS anodes.
Syntheses were performed at room temperature by solution phase reduction of germanium precursors in the presence of the HCNS to produce conductive composites of Ge nanoparticles supported on HCNS. When cycling from 1.5 to 0.02 V vs. Li, a stable capacity of ~600 mAh/g electrode ( ~1200 mAh/g Ge) was obtained with average capacity fade of 0.03% per cycle. Long-term coulombic efficiency values were 99.9 and 99.6% for 20 and 40% Ge/HCNS, respectively. Owing to the high volumetric capacity of Ge and porous structure of the HCNS, areal capacities of ~2.5 mAh/cm2
could be obtained by slurry casted techniques. Performance comparisons of multiple Ge/HCNS compositions with differing cycling environments will be presented.
(1) Michael J. Wagner, J. Thomas McKinnon, J. Cox and K. Gneshin, “Hollow Carbon Naonsphere Based Secondary Cell Electrodes”, United States Patent 8,262,942, September 11, 2012.

Figure 1
Three-Phase 3D Reconstruction of Li-Ion Batteries Electrodes Via FIB-SEM Tomography
Authors: Liu Zhao , Wang Hongqian , Singh Deepak P. , Wagemaker Marnix , Faber Katherine T , Barnett Scott A 
Published: February 2020

Three-dimensional (3D) reconstructions of lithium-ion battery electrodes provide quantitative microstructural characteristics and input for 3D computational modeling of electrode lithiation and de-lithiation (1-3). In much of the work reported to date, it was not possible to identify all three electrode phases – oxide particles, carbon, and electrolyte – because there was little or no image contrast between the carbon-based epoxy used to fill the pore regions of the electrode (after electrolyte removal) and the carbon phase (4). Recently, it was shown that filling with a silicone resin allows good electrolyte/carbon contrast, although the high viscosity of the resins may make effective pore filling difficult (5).
In this work, three-phase 3D reconstructions of a commercial LiCoO2 cathode and lab-made LiFePO4 cathodes (6) are demonstrated using a low viscosity silicone resin as a filling material. As illustrated in Figure 1, contrast among oxide, carbonaceous materials (conducting carbon and binders, CB) and resin-filled porosity (electrolyte space) is obtained using focused ion beam-scanning electron microscopy tomography. Structural parameters including, phase volume fraction, surface area, particle size distribution, pore connectivity and tortuosity are extracted for electrode microstructure-performance correlation analyses. For the commercial LiCoO2 cathode, the electrolyte tortuosity within the electrode is found to be inhomogeneous. For LiFePO­4 cathodes, the microstructure characteristics are compared with conventional electrodes and those with additional large-scale pores added using a sacrificial templating technique. The improved high rate performance found in the templated LiFePO4 electrode can be explained by 3D microstructural characteristics created by the sacrificial template. The present study demonstrates the importance of obtaining all three phases for accurate analysis of microstructure-performance correlations.
1. Z. Liu, J. Scott Cronin, Y.-c. K. Chen-Wiegart, J. R. Wilson, K. J. Yakal-Kremski, J. Wang, K. T. Faber and S. A. Barnett, Journal of Power Sources, 227, 267 (2013).
2. Andreas H. Wiedemann, Graham M. Goldin, Scott A. Barnett, Huayang Zhu and R. J. Kee, Electrochemica Acta, 88, 580 (2013)
3. T. Hutzenlaub, S. Thiele, N. Paust, R. Spotnitz, R. Zengerle and C. Walchshofer, Electrochimica Acta, 115, 131 (2014).
4. J. R. Wilson, J. S. Cronin, S. A. Barnett and S. J. Harris, Journal of Power Sources, 196, 3443 (2011).
5. M. Ender, J. Joos, T. Carraro and E. Ivers-Tiffee, Journal of the Electrochemical Society, 159, A972 (2012).
6. D. P. Singh, F. M. Mulder, A. M. Abdelkader and M. Wagemaker, Advanced Energy Materials, 3, 572 (2013).

Figure 1
Design and Optimization of 3DSi Electrode for Li-Ion Battery Applications
Authors: Ababtain Khalid Abdullitife , Arava Leela mohana reddy , Ganguli Babu 
Published: February 2020

Abstract

Lithium ion batteries are revolutionized today's information-rich e-society due to their light weight and high energy density. Despite their great success in portable electronic devices at the present time, interest is continued in advancing new and improved electrode materials for lithium ion batteries with higher energy capacity and longer cycle life. Silicon is one of the most promising anode materials for lithium batteries, as it appeals with highest theoretical specific capacity (4200 mAh/g) among known materials, relatively low cost, and environmental benignity. However, silicon anodes suffering from huge volume change associated with the insertion and extraction of lithium during charge-discharge process. Such an unavoidable volume changes result to cracking and pulverization of the anode, which leads to a loss of electrical contact and eventual fading of capacity upon cycling. Herein, we report a porous three-dimensional framework of current collectors to form 3DSi nanostructure to provide continuous electron transport network and accommodate the volume expansion of Si particles.
3D porous Ni current collectors are prepared by galvanostatic electrodeposition with tuning its experimental parameters such as deposition current and pH of bath solution etc. Silicon is deposited conformally by plasma enhanced chemical vapor deposition (PECVD) technique. During PECVD process, parameters such as time, flow rate of the silane gas (SiH4), pressure and power are optimized to ensure uniform conformal coating of Si to form desired three-dimensional silicon structure. X-ray diffraction and Microscopy analysis revealed the formation of 3DNi current collectors by electrodeposition and conformal coating of Si by PECVD. Electrochemical studies such as cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge studies have been carried out to understand the influence of 3D structure on silicon capacity and cycle life properties. Such a 3D Si electrodes exhibit capacity of 2600 mAh/g with an excellent columbic efficiency at 0.2 C rate for 100 cycles. Further, full cell configuration has been fabricated using LiFePO4/C cathode to demonstrate feasibility of presently designed 3D Si electrode for high capacity Li-ion battery applications.
# - Corresponding Author - leela.arava@wayne.edu
Metal Oxide Anode Materials for Lithium-Ion Batteries
Authors: Mustain William E , Liu Ying , He Junkai , Meng Yongtao , Suib Steven 
Published: February 2020

Lithium-ion batteries have become the most popular power source for portable electronics, offering very good energy density, along with favorable stability and efficiency [1]. At the Li-ion anode, graphitic carbons have been ubiquitous [2], though these materials may lack sufficient energy density to enable grid or home-scale energy storage or the realization of fully electric vehicles with sufficient driving range. Therefore, recent years have seen a shift in focus to the development of materials with higher capacity than graphite.
Metal oxides are a promising family of materials that could potentially replace graphite as the anode in lithium-ion batteries. Metal oxides typically do not intercalate lithium during charging process, but rely on chemical transformations with more than one electron transfer to store and deliver energy, which results in much higher capacities. In addition, they also have a safer lithiation potential that eliminates the problematic lithium plating process during charging. However, the use of metal oxides has been limited mainly by their low electrical conductivity, and inferior cycling stability [3-5]. To circumvent these challenges, nanostructured metal oxides and their composites with advanced carbon materials, such as graphene, can be used to improve their capacity retention by suppressing phase segregation during charge/discharge and volumetric expansion, as well as enhancing ionic and electronic transport.
In this work, the interaction between metal oxides (Co3O4, SnO2, NiO, MnO2) and several carbon substrates was explored using a combination of electrochemical and physical characterization. Increased interfacial interaction between carbon and metal oxide, while minimizing the carbon loading, is critical to improve battery performance. Excellent capacity retention and rate capability can be realized through a combination of material chemistry and structure, and promising approaches to achieve this will be the focus of this presentation.
[1] Tarascon. J, Armand. M, Nature, 414 (2001) 359.
[2] Sawai. K, Ohzuku. T, J. Electrochem. Soc., 150 (2003) A674.
[3] Lee, S. H.; Kim, Y. H.; Deshpande, R.; Parilla, P. A.; Whitney, E.; Gillaspie, D. T.; Jones, K. M.; Mahan, A. H.; Zhang, S. B.; Dillon, A. C., Adv. Mater., 20 (2008) 3627.
[4] N.S. Spinner, A. Palmieri, N. Beauregard, L. Zhang, J. Campanella and W.E. Mustain, J. Power Sources, Accepted.
[5] N. Spinner, L. Zhang and W.E. Mustain, J. Mat. Chem. A, 2(6) (2014) 1627-1630.
Improved Structural and Electric Characterstics of Al/ALD-HfO2/Ge MOS Capacitor by Germanium Dioxide and Germanium Oxynitride as Interfacial Layer
Authors: Prasher Rakesh , Dass Devi , Vaid Rakesh 
Published: February 2020

In this work HfO2 thin films has been deposited on Ge substrate by ALD with thickness of 9.77 nm. Thickness evaluation of film was done by Spectroscopic Ellipsometer (SE) and Filmetrics Reflectometer whereas chemical compositions and the states of the elements of the films were investigated by X-ray Photoelectron Spectroscopy (XPS). High-frequency Capacitance-Voltage (C-V), Conductance-Voltage (G-V) techniques and Current-Voltage (I-V) measurement were used to obtain the electrical properties of the high-k MOS capacitor. Different Ge surface cleaning methods preceding high-k ALD have been used for reducing oxide traps. Rapid Thermal Oxidation (RTO) and Rapid Thermal Nitridation (RTN) have been used to form the gate interlayer (IL) of GeO2 and GeON for the gate stack of P-MOS capacitor. By assimilating a thin GeON interlayer, excellent MOS capacitors with very small capacitance–voltage hysteresis and low gate leakage have been demonstrated. Physical and Electrical characterization investigates the quality of the oxynitride interlayer and low interface trap density (Dit ≈ 0.63×1012eV-1cm-2) in case of GeON/Ge which is improved as compared to the GeO2/Ge interface (Dit ≈ 2.53×1013 eV-1cm-2). Further electrical characterizations of HfO2 gate dielectric MOS capacitors deposited by the ALD using RTO & RTN as IL were investigated for the measurement of EOT and Qeff. The calculated EOT and Qeff values for GeON/Ge are 3.23 nm and 16.92×1012 cm-2 respectively which is better in comparison with GeO2 and as deposited samples.
(Invited) Preparation of GaSb Surface for Low Interfacial Trap Density MOS Capacitors
Authors: Chen Chen-Yu , Hsueh Wei-Jen , Chang Chao-Min , Hsu Hsien-Ming , Chyi Jen-Inn 
Published: February 2020

High mobility III-V compound semiconductors have been extensively investigated recently for future complementary metal-oxide-semiconductor (CMOS) applications. GaSb, which has high electron and hole mobilities as well as a narrow bandgap is an attractive material for future high-speed and low-power integrated circuits. Due to the easy formation of native oxides, i.e. SbOx, GaOx, and elemental Sb clusters on GaSb surface, Fermi-level pinning and high interfacial trap density (Dit) has been a major obstacle to high quality MOS devices. In this talk, we will present both in-situ and ex-situ techniques to prepare GaSb surface and realize metal-oxide-semiconductor capacitors (MOSCAPs) with low interfacial trap density.
The i
n-situ approach is conducted in a system equipped with a high vacuum sample transfer tube that connects a molecular beam epitaxy (MBE) tool and an atomic layer deposition (ALD) chamber. A native oxide-free surface can thus be preserved for high-κ dielectrics deposition. HfO2/Al2O3/GaSb MOSCAPs fabricated on Sb-stabilized surface exhibit clear inversion behavior at low frequency and good modulation of the Fermi level across the whole GaSb band gap. Modulation of the inversion capacitance at 100 kHz reaches 30 %, suggesting low Dit as well as low bulk trap density at the interface. The Dit extracted by the conductance method is about 7.6×1011 cm-2eV-1 near the valence band. As to the ex-situ process, air-exposed GaSb samples are treated by hydrogen plasma at room temperature prior to ALD dielectrics. Under optimized plasma treatment conditions, similar C-V characteristics and gate leakage current of HfO2/Al2O3/GaSb MOSCAPs to those of the in-situ ones are observed. Modulation of the inversion capacitance at 100 kHz even reaches 36 % and the Dit near the valence band is as low as 6.0×1011 cm-2eV-1.
Structural and chemical analyses of the dielectric/semiconductor interface by high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS) show that the in-situ MOSCAPs have a native oxide-free interface, while hydrogen plasma treatment results in the formation of GaOx, which may serve to passivate defects and dangling bonds at the GaSb surface
Invited: Ohmic Contacts to Semiconductor Compounds: From III-V Semiconductors to Layered Transition Metal Dichalcogenides
Authors: Mohney Suzanne E. 
Published: February 2020

In this presentation, I will review work on low-resistance ohmic contacts to III-V semiconductors, particularly our group’s most recent work on contacts to InGaAs. Then I will discuss contacts to layered transition metal dichalcogenide semiconductors and how some of the lessons learned from III-V semiconductors may apply to contacts to the transition metal dichalcogenides. I will also highlight important differences between the families of materials and their ramifications for forming low-resistance ohmic contacts to layered semiconductor compounds.
To realize low-resistance ohmic contacts to semiconductors, it is necessary to understand and control many factors. The Schottky barrier between the metal and semiconductor should be minimized but is not always strongly affected by the choice of metal due to Fermi level pinning. The Schottky barrier can also be affected by the preparation of the semiconductor surface prior to metallization and the presence of intentional or unintentional interfacial oxide layers. I will discuss this effect in contacts to heavily doped n-type InGaAs, particularly Ni contacts of interest for self-aligned “salicide-like” processes. I will also discuss a possible explanation for the vastly different values of specific contact resistance reported by different groups that have studied these Ni contacts.
The interfacial reactions between a metal and semiconductor can be used in many ways to engineer current transport through contacts, so it is beneficial to understand the contact metallurgy­–both phase equilibria and reaction kinetics. This topic has been studied extensively for contacts III-V semiconductors. As a recent application, I will highlight the introduction of co-dopants (Si and S) through solid-state reactions to form a shallow ohmic contact to n-type InGaAs, which resulted in an exceptionally low contact resistance on lightly doped n-type InGaAs.
Finally, I will discuss our newest studies on contacts to transition metal dichalcogenide semiconductors. I will present information on phase equilibria and reaction kinetics in metal-Mo-S systems and their implications for contacts to MoS2. Then I will compare these systems to the metal-III-V systems and predict how reactions and surface preparation will be important for engineering contacts to layered transition metal dichalcogenide semiconductors.