bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing the Electrochemical Performance of NaCrO2 through Structural Defect Control
Authors: Luo Mei , Ortiz Angel , Shaw Leon
Published: May 2020

It is known that structural defects have impacts on electrochemical properties of layered transition metal oxide cathode materials such as O3-NaCrO2 for Na-ion batteries. However, this study clarifies, for the first time, that misplacement of Cr3+ ions at the Na1+ site plays a more important role in dictating the specific capacity and capacity retention over charge/discharge cycles than the Na-O bond length and the NaO2 interlayer spacing. It is shown that O3-NaCrO2 crystals with lower degree of misplacement of Cr3+ ions at Na sites and longer Na-O bond length have higher specific capacity (i.e., 115 mAh/g for the first discharge), better capacity retention (91% capacity retention for the first 50 cycles), and smaller cell impedance than O3-NaCrO2 crystals with higher degree of misplacement of Cr3+ ions at Na sites and shorter Na-O bond length (68 mAh/g for the first discharge and 64% capacity retention for the first 50 cycles). Furthermore, O3-NaCrO2 crystals with high degree of cation mixing at the Na plane exhibit the formation of some monoclinic Oꞌ3-NaCrO2 crystals over 300 cycles between NaCrO2 and Na0.5CrO2 formulas, whereas the rhombohedral structure of O3-NaCrO2 crystals with low degree of cation mixing at the Na plane is fully reversible. The effects of structural defects discovered in this study are interpreted based on the interference of Cr ions in Na transport on the Na plane and gradual migration of Cr ions to the Na plane during cycles. The insights established in this study will provide guidance in rational design and synthesis of NaCrO2 cathode materials with high specific capacity and long-term cycle stability in the future.
Liquefied Gas Electrolytes for All-Temperature Lithium Metal Batteries
Authors: Yang Yangyuchen , Yin Yijie , Davies Daniel M , Borodin Oleg , Lee Jungwoo Z. , Rustomji Cyrus S. , Meng Ying Shirley
Published: May 2020

Among the several challenges to enable next-generation batteries is the development of an electrolyte which compatible with both lithium (Li) metal anode and high-voltage cathode at wide temperature range. Liquefied gas electrolytes with a new cosolvent and higher salt concentration show improved ionic conductivity of > 4 mS/cm at wide temperature range from -80 to +70 °C. With a new solvation structure, the liquefied gas electrolytes demonstrated high-temperature operation of Li-metal batteries at 55°C, which is the operation above the electrolytes’ critical point for the first time. The electrolytes enable improved Li metal stability and coulombic efficiency at aggressive current and capacity of 3 mA·cm-2 and 3 mAh·cm-2 with average coulombic efficiency of 99%. The use of liquefied gas electrolytes presents stable cycling of Li/NMC (4.4 V) cell at all-temperature range between -60 and 55°C. This study opens up a promising avenue toward the applications of all-temperature high energy density Li-metal batteries.
Extremely Fast Solvers for Newman-Type Models of Li-Ion Cell (dis)Charge
Authors: Korotkin Ivan , Richardson Giles , O'Kane Simon , Foster Jamie M
Published: May 2020

The Newman model for charge transport within porous electrodes was developed by Newman, Fuller and Doyle in the mid-90s, and has become the standard tool for simulating Li-ion cell (dis)charge. The model is comprised of a system of nonlinear partial differential equations that must, in general, be solved numerically.

The computational costs associated with solving the Newman model, even for a single planar cell, are relatively high; for example, most solvers take several minutes to compute a single discharge curve. This makes its application to computationally expensive problems (such as cell optimisation, parameter estimation or battery pack simulation) problematic. Motivated by the lack of a fast Newman solver in the literature we have developed a new software tool, named DandeLiion. This provides extremely fast code with which to solve the Newman model. It is straightforward to install, comes with concise and clear documentation, is fully parallelisable and free to use. As an example of its power it has the capability of simulating a full discharge curve in less than a second (with fully nonlinear transport and sufficient resolution to compute the solution to several digits of accuracy) which is approximately several hundred times faster than most commercial solvers. In addition, it is equipped with a library of battery chemistries that incorporates models for nonlinear lithium transport and open circuit voltage in most active electrode materials, and for lithium transport and conduction in the most common electrolytes. This gives the user the ability to simulate a wide range of devices designs. It can also be used to simulate realistic drive cycle data.

In order to illustrate the power of this software we perform a thermally coupled simulation in a realistic pouch cell geometry, using DandeLiion to compute the electrochemical discharge of the cell stack in the resulting three-dimensional evolving temperature field. We note that such thermally coupled pack simulations are normally performed using simple equivalent circuit models of the cell, rather than the Newman model, because the computational cost associated with a thermally heterogenous Newman model has, up until now, been too high.
Advanced 18650 Lithium-Ion Batteries with LiMn2O4@Carbon Core-Shell Cathode and Si/Mcmb Anode
Authors: Tomon Chanikarn , Sarawuthanukul Sangchai , Wutthiprom Juthaporn , Phattharasupakun Nutthaphon , Sawangphruk Montree
Published: May 2020

Nowadays, the 18650 cylindrical cells of lithium-ion batteries using cobalt-containing cathode materials have currently produced with a purpose of operating source of electric-powered application such as electric vehicle (EV), hybrid electric vehicle (HEV), and small-scale energy storage system (ESS). However, cobalt is not abundant and expensive. Thus, cobalt-free cathode materials are of interest. In this work, 18650 lithium-ion battery using LiMn2O4/Carbon core-shell (LMO@C) cathode and Si/MCMB anode. The LMO@C materials was synthesized bya sonvent-free mechanofusion method with a highly uniform coating. The LMO particles with fully covered by carbon nanoparticles can exhibit higher capacity ca. 10-15% as compared with the pristine LMO.In addition, the LMO@C also presents the superb rate capacity retention as well as cycling stability due to the improved intrinsic conductivity and mechanical property.
Decoration of Pd Porous Structures on Perovskite Oxides to Improve Li-Air Battery Performance
Authors: Nahm Kee Suk , Oh Mi-Young , Park Hyoseok
Published: May 2020

Perovskites La0.6Sr0.4CoO3-δ (LSC) and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) are still low in the catalytic activity of oxygen reduction reaction (ORR) although it exhibits relatively good catalytic activity for oxygen evolution reaction (OER). In this work, palladium (Pd) was deposited over the LSC surface to improve the ORR activity of the LSC. The Pd decorated perovskite La0.6Sr0.4CoO3-δ (Pd/LSC) was characterized by using various analytic techniques. Pd was deposited on the surface of LSC powders in nanostructured forms without giving a influence on the crystallinity of LSC. The surface area of the Pd/LSC samples dramatically increased over 10 wt% due to the formation of Pd porous structure over the perovskite surface. The electrochemical characterization of the Pd/LSC was examined in both aqueous and non-aqueous electrolyte solutions. In aqueous electrolyte, the Pd/LSC materials exhibited higher ORR and OER activities than LSC and KB. The ORR activity rapidly increased with the increase of Pd wt% deposited in order of 5<10<20<30, though the OER activity displayed not much different values for all the Pd weight percentages. The Pd/LSC materials were applied as air cathode catalyst of lithium air battery to examine their catalytic performances in non-aqueous electrolyte. The highest discharge capacity and the longest cycle life were observed over 30wt% Pd/LSC catalyst. It is concluded that the decoration of Pd over perovskite LSC oxide was more effective to increase the ORR activity, resulting in increasing the performance of lithium air battery.

References

[1] Mi Young Oh et. al., Journal of Industrial and Engineering Chemistry, 80 (2019) 686–695.]
Redox Mediators Degradation By Singlet Oxygen in Lithium Oxygen Batteries
Authors: Kim Hun , Sun Yang-Kook
Published: May 2020

Non-aqueous lithium-oxygen batteries cycle by forming and decomposing the lithium peroxide to deliver a capacity. During charging, oxidizing the solid insulating lithium peroxide can greatly be facilitated by redox mediators which shuttle electron-holes between the porous substrate and lithium peroxide. Redox mediator stability is thus key for energy efficiency, reversibility, and cycle life. However, the gradual deactivation of redox mediators during repeated cycling has not conclusively been explained. Here, we show that organic redox mediators are predominantly decomposed by singlet oxygen that forms during cycling. Their reaction with superoxide, previously assumed to mainly trigger their degradation, peroxide, and dioxygen, is orders of magnitude slower in comparison. The reduced form of the mediator is markedly more reactive towards singlet oxygen than the oxidized form, from which we derive reaction mechanisms supported by density functional theory calculations. Thus, design of redox mediators considers the stability against singlet oxygen.

References:

1. Kwak, W.-J.; Kim, H.; Jung, H.-G.; Aurbach, D.; Sun, Y.-K. Review—A Comparative Evaluation of Redox Mediators for Li-O 2 Batteries: A Critical Review. J. Electrochem. Soc.
2018, 165, A2274–A2293.

2. Mahne, N.; Schafzahl, B.; Leypold, C.; Leypold, M.; Grumm, S.; Leitgeb, A.; Strohmeier, G. A.; Wilkening, M.; Fontaine, O.; Kramer, D.; et al. Singlet Oxygen Generation as a Major Cause for Parasitic Reactions during Cycling of Aprotic Lithium–Oxygen Batteries. Nat. Energy
2017, 2, 17036.

3. Kwak, W.-J.; Kim, H.; Petit, Y. K.; Leypold, C.; Nguyen, T. T.; Mahne, N.; Redfern, P.; Curtiss, L. A.; Jung, H.-G.; Borisov, S. M.; et al. Deactivation of Redox Mediators in Lithium-Oxygen Batteries by Singlet Oxygen. Nat. Commun.
2019, 10, 1380.
Microwave Fusion of the Composite LiMn1.6Ni0.4O4-LiFePO4 /C to Improve the Stability of Spinel Phase
Authors: Vásquez Ferley , Rosero Carolina , Miura Akira , Calderon Jorge , Tadanaga Kiyoharu
Published: May 2020

Lithium-ion batteries are a promissory technology for energy storage devices in electric vehicles and renewable energy generation systems. Lithium nickel manganese oxides (LMNO, spinel structure) are promising cathode materials for lithium-ion batteries because of their high potential (4.7V vs. Li/Li+, 147 mAhg-1), moderate thermal stability and environmental friendliness. However, their chemical stability and electronic conductivity needs to be improved for practical applications. The microwave fusion of composite material LiMn1.6Ni0.4 (LMNO, spinel) coated with LiFePO4 /C (LFP, olivine structure) is studied in order improve the stability of active material without reducing the active sites for lithium intercalation. Synchrotron diffractions shows superior crystallographic order and no further impurities precipitation for the composite material heated at 10W (see Figure 1). Electrochemical characterizations shows high cycled stability for LMNO-2LFP/C heated at 10W (97% after 100th cycles) (see Figure 2). The composite materials heated at 100W presents lower discharge capacity due to the changes in the lattice parameters and impurities precipitation during microwave heating. Sincrotron diffraction after 60th cycle in composite material heated at 10W shows the same lattice parameters for spinel phase and the reductions of lattice parameters for olivine structure in “b” direction.

Figure 1
Synthesis and Performance Evaluation of SiO2 Coated Li-Rich Li1.2Ni0.13Mn0.54Co0.13O2 Cathode Materials for Li-Ion Batteries
Authors: Shakoor Rana Abdul , Abraham Jeffin James , Monawwar Haya , Quddus Aisha Abdul , Tariq Hanan , Saleh Ismail , Kahraman Ramazan , Al-Qaradawi Siham Y.
Published: May 2020

Lithium rich layered oxides (LLO) are one of the potential candidates for Li-ion batteries. however, LLO materials have serious drawbacks such as poor cyclic stability, poor rate capability and rapid voltage decay upon cycling, which needs to be overcome in order to successfully commercialize them. In this work, SiO2 coating is employed (1.0%, 1.5%, and 2.0 wt. %) to combat these issues. Li1.2Ni0.13Mn0.54Co0.13O2 synthesis was carried out by sol-gel process and SiO2 coating was done using dry ball milling method. XRD analysis confirmed the synthesis of phase pure materials without the presence of any impurity phases. SEM and TEM analysis showed the synthesis of nanometric sized particles. Furthermore, TEM elemental mapping displayed the homogeneous distribution of SiO2 on the cathode particles. XPS was further employed to confirm the SiO2 on the cathode material. The electrochemical analysis showed that 1.0 wt.% SiO2 displayed the best performance in terms of rate capability. Uncoated Li1.2Ni0.13Mn0.54Co0.13O2 displayed a fast capacity fade, especially at higher C-rate. On the other hand, SiO2 coated Li1.2Ni0.13Mn0.54Co0.13O2 materials showed improved rate capability. Coated materials also showed improved cycling performance when compared with bare Li1.2Ni0.13Mn0.54Co0.13O2. The improved electrochemical performance can be attributed to the positive impact of SiO2 coating, which impedes the electrolyte oxidation by preventing the direct contact of cathode active material and electrolyte. Overall, the SiO2 coating had a positive impact on the electrochemical performance of Li1.2Ni0.13Mn0.54Co0.13O2 and can pave the way for commercialization of LLO materials.
(Invited) Stability and Evolution of Solid Electrolyte Interphase on Silicon Anodes
Authors: Ban Chunmei
Published: May 2020

Solid electrolyte interphase (SEI), which forms at the interface between the electrolyte and the electrode, can passivate the surface of graphite anodes and finally facilitate the intercalation of lithium ions into graphite electrodes. However, the concept of only using SEI protects the electrode surface from the reductive electrolyte may be not applicable for silicon (Si) anodes. Different from the intercalation chemistry in graphite anodes, Si anodes experience alloying/dealloying reactions during electrochemical process, leading to phase transformation, morphology and volumetric changes. It generates great complexity in understanding the formation and the structural/composition evolution of the SEI layer during electrochemical process. Considering the high theoretical capacity Si anodes can offer, the investigation of SEI behavior on Si anodes is critical for developing next-generation anode materials. This presentation, which is based on recent results from advanced electrochemical and spectroscopy characterization, systematically elaborates the chemical and physical properties of SEI toward mitigation strategies for stabilizing SEI on Si anodes.
Tunable Syntheses of Advanced Silicon Anodes Using Cyclohexasilane
Authors: Elgammal Ramez Ahmed
Published: May 2020

The ability to develop fast charging lithium-ion batteries with high-energy density is being pursued intensively due to increasing demands of portable electronics and electric vehicles. Replacing the conventional graphite anode with a silicon-based one offers several advantages, namely the roughly 10 times higher gravimetric capacity and the safer lithium alloying potential. However, full scale realization of replacing graphite with silicon has been hampered due to the large volumetric expansion silicon typically suffers which causes mechanical degradation, low electrical conductivity, and multiple-step syntheses from a traditional silicon precursor which leads to higher cost. Here we present a silicon precursor, cyclohexasilane, that can offer solutions to all three of those limitations. Cyclohexasilane (CHS) exists as a liquid at room temperature and is relatively low boiling (~ 200 °C) relatively facile synthesis of nanostructured silicon materials, significantly reducing the volumetric expansion typically observed. Cyclohexasilane can be readily used to manufacture silicon/carbon composite materials and is readily chemically functionalized allowing the development of tailored materials with improved electrical conductivity. CHS may also be tailored to deliver structures with engineered artificial SEIs during the device fabrication step, offering an efficient and direct route to electrode structures. Moreover, cyclohexasilane is relatively inexpensive and its physical properties allow for roll-to-roll manufacturing with significantly reduced capital costs. Relevant comparisons of this technology compared to incumbent technologies will be given.
(Invited) Dielectric Science on Today's Devices
Authors: Misra Durgamadhab
Published: May 2020

Device scaling in CMOS technology has approached to 10nm range and below. The gate dielectric, being the critical constraint, has evolved significantly and requires constant quality improvements in order to keep the proper functioning of the transistors and memory devices. While the transistor has transformed from a planar device to a three-dimensional device to a gate all around device, several new devices such as ferroelectric FETs and negative capacitance FETs have emerged to be integrated into standard CMOS technology. Additionally, many forms of memory devices such as resistive random-access memory (ReRAM) devices and ferroelectric RAM devices are being investigated for possible implementation of artificial intelligence hardware. All these devices use high dielectric constant (high-k) materials in some form or other. The electrical performance in these devices depends on the dielectric deposition process, precise selection of deposition parameters, pre-deposition surface treatments and subsequent thermal budget. In this work we describe the evolution of dielectric science in nanoelectronics.

For logic devices, once the thickness of SiO2 reached the onset of direct tunneling region (<1.5 nm) high-k insulators were introduced to suppress the direct-tunneling leakage current. Because of thermal stability, HfO2-based high-k dielectrics were selected to replace SiO2. To resolve issues like mobility degradation, threshold voltage control and Fermi-level pinning, HfO2-based high-k gate dielectrics was introduced with an interfacial SiO2 layer on silicon devices. Subsequently, higher-k dielectrics are required for transistors performance enhancement to keep up with the scaling without reducing the physical dielectric thickness. It was achieved by controlling the structural phase of HfO2 by doping HfO2 with various metal oxides including ZrO2 as cubic, or tetragonal phase that provides higher-k than amorphous or monoclinic phase. By considering the interface reaction kinetics and thermal budget various atomic layer deposition (ALD) schemes were identified to get a stable dielectric with a robust interface. We will discuss the deposition of Hf1-xZrxO2 or HfAlOx on both silicon and germanium, a higher mobility channel material. The reliability characterization of these dialectics based on dielectric-semiconductor interface will also be discussed.

In ReRAM devices, the resistance change, achieved in a dielectric material between two metal terminals by applying a voltage, is promising for further scaling of memory devices. The switching mechanism in transition metal oxides like HfO2 is, while evolving, based on similar mechanism to soft breakdown, where a conducting filament path is formed due to oxygen vacancy transition/formation. The process is reversed by rupturing the filament. Various dielectric stacks are currently being studied for ReRAM applications. Additionally, ferroelectric characteristics of HfZrO films also derived significant attention recently. Some of the current trends in memory devices involving high-k dielectrics will be discussed.
(Invited) Advanced Transistors for High Frequency Applications
Authors: Parvais Bertrand , Peralagu Uthayasankaran , Vais Abhitosh , Alian AliReza , Witters Liesbet , Mols Yves , Walke Amey , Ingels Mark , Yu Hao , Putcha Vamsi , Khaled Ahmad , Rodriguez Raul , Sibaja-Hernandez Arturo , Yadav Sachin , ElKashlan Rana , Baryshnikova Marina , Mannaert Geert , Alcotte Reynald , Kunert Bernardette , Simoen Eddy , Zhao Ellen , De Jaeger Brice , Fleetwood Daniel , Langer Robert , Zhao Ming , Wambacq Piet , Waldron Niamh , Collaert Nadine
Published: May 2020

The growing interest for 5G radios pushes technology development towards low-cost and high-performance solutions for operating at microwave and mm-wave. Downscaling CMOS technology has allowed the integration of high-speed transceivers on silicon chips, but high-power amplifiers rely on III-V technologies to deliver the power and efficiency levels required by modern radios.

In this work, we motivate the interest of non-Si technologies to meet 5G requirements, and we explore two routes to enable the fabrication of compound semiconductor devices on a large-scale manufacturable Si platform [1,2]. We provide insight on the potential of these new technologies for the design of advanced front-end modules, including modelling and reliability challenges.

In the first route (Figure 1(a)), we report on Al(Ga,In)N HEMTs, MISHEMTs and MOSFETs integrated on 200 mm Si wafers using Au-free processing in standard Si CMOS tools, and discuss the performance trade-offs, limitations and solutions. State-of-the-art contact resistance of 0.14 Ω.mm is demonstrated for a non-Au, low thermal budget (<600 oC) contact scheme, as well as a high vertical breakdown voltage (VBD) of >300 V. We show that MISHEMTs, which feature the highest field effect mobility (μFE), >2000 cm2/V.s, and the best 1/f noise performance, have the potential to outperform the other device types in terms of device scalability for high frequency operation. The GaN-on-Si substrate optimization for low RF losses and nonlinear distortion is further discussed.

The second route (Figure 1(b)) includes the formation of HBT on Si wafer by selective epitaxy. We demonstrate GaAs/InGaP HBTs grown on a 300 mm Si substrate. A DC current gain of ~112 and breakdown voltage, BVCBO, of 10 V is achieved. The emitter-base and base-collector diodes show an ideality factor of ~1.2 and ~1.4, respectively. This demonstration shows the potential for enabling a hybrid III-V CMOS/ technology for 5G and mm-wave applications, not limited to GaAs but which can also be extended to InGaAs on a 300 mm Si substrate.

Figure 1
(Invited) Junctionless Device Cross-Section: A Key Aspect for Overcoming Boltzmann Tyranny
Authors: Kranti Abhinav , Gupta Manish
Published: May 2020

The demonstration of higher impact generate rate at relatively lower applied biases in a junctionless transistor (JLT) [1-2] has renewed interest in its device physics, operation and technology downscaling. This phenomenon is particularly interesting as it can lead to an associated steep current switching from off-to-on state with a subthreshold swing lower than 60 mV/decade [3-4]. A 3dimensional tri-gate JLT while offering immunity from short channel effects due increased gate controllability offers an additional degree of freedom apart from gate length and drain bias to tune the impact generation rate. Since JLT is a heavily doped device (figure 1(a)), the cross-section governs the concentration of carriers in the channel available for impact ionization and steep switching. Hence, the cross-section of a 3d JLT is expected to serve as a key facilitator for steep switching.

Figure 1(b) shows the comparison of the 3d simulations exhibiting a sharp increase in current in a JLT with the available experimental data [1]. The default models of TCAD simulation tool [5] were calibrated to ensure a reasonable agreement with published results. Figure 1(c) shows the drain current (I
ds) – gate voltage (V
gs) characteristics of JLT for two different device cross-sections. The lower aspect ratio (AR = 0.2) JLT exhibits a lower subthreshold swing (SS) of 3 mV/decade while a JLT with AR of 1 showcases a conventional SS of 60 mV/decade. As shown in figure 1(d), results clearly indicate that device cross-section of a 3d JLT is crucial for overcoming the Boltzmann tyranny, and should be a crucial component for device design and operation. The research work demonstrates new possibilities through the optimization of 3d cross-section of a JLT for attaining a sharp enhancement of drain current at shorter gate lengths.

References:

[1] C.-W. Lee et al., Applied Physics Letters, 96, 102106, 2010.

[2] S.M. Lee et al., IEEE Trans. Electron Devices, 60, 11, 3856-3861, 2013.

[3] M. Gupta et al., IEEE Trans. Electron Devices, 65, 6, 2406-2412, 2018.

[4] M. Gupta et al., IEEE Trans. Electron Devices, 64, 5, 2061-2066, 2017.

[5] ATLAS User’s Manual, Silvaco.

Figure 1
Enabling Fast Charging Lithium-Ion Batteries through Highly Ordered Laser-Patterned Electrode Design
Authors: Chen Kuan-Hung , Namkoong Min Ji , Goel Vishwas , Yang Chenglin , Mazumder Jyoti , Thornton Katsuyo , Sakamoto Jeff , Dasgupta Neil P.
Published: May 2020

Current Li-ion battery technology is highly optimized for performance at relatively slow charging rates. However, significant challenges still present for fast charging conditions (< 15-minute charge time). These bottlenecks include large kinetic polarizations, concentration gradients, and Li plating on the anode surface.1 In state-of-the-art Li-ion batteries with high energy densities, the electrodes are relatively thick (> 50 μm), which leads to a tradeoff between energy density and high-power performance. Thicker electrodes with tortuous pathways limit Li-ion transport through the electrode thickness, leading to large electrolyte concentration gradients during cycling. This results in large cell polarizations, which reduce the accessible capacity of the battery. In addition, the electrochemical potential of the graphite anode can become more negative than the thermodynamic potential of Li metal during fast charging, resulting in Li plating. Therefore, to simultaneously achieve fast charging and maintain energy density of Li-ion batteries, new approaches are required to address Li ionic transport limitations through the thick graphite anodes.

In this work, we demonstrate a structural modification of conventional graphite anodes to improve their fast charge capability. This is achieved by introducing laser-patterned vertical channels into post-calendared graphite anodes2. This 3-D electrode architecture consists of a hexagonal close-packed array of vertical channels that serve as linear pathways for rapid ionic diffusion through the electrode thickness, allowing for a more homogeneous flux of Li throughout the volume of the electrode and decreased ionic concentration gradients. As a result, the accessible capacity of the electrode can be significantly improved and Li plating can be minimized during fast charging. Utilizing the 3-D electrode design, we demonstrate significant improvement in capacity fade at 4C (15-minute) and 6C (10-minute) charge rate with industrial-relevant electrode material and loading (3 mAh/cm2 electrode loading in >2Ah pouch cells). This work thus demonstrates the viability of realizing high energy density Li-ion batteries with fast charge capability based on thick electrodes.

References:

1. Ahmed, S. et al. Enabling fast charging e A battery technology gap assessment. J. Power Sources
367, 250 (2017).

2. Kim, Y., Drews, A., Chandrasekaran, R., Miller, T. & Sakamoto, J. Improving Li-ion battery charge rate acceptance through highly-ordered hierarchical electrode design. Ionics
24, 2935 (2018).
Visualization of Internal Potential Distribution in an All-Solid-State Fluoride Shuttle Battery Using Operando Hard X-Ray Photoelectron Spectroscopy
Authors: Kiuchi Hisao , Sakurai Katsutoshi , Okazaki Ken–ichi , Nakanishi Koji , Morita Yoshiyuki , Matsubara Eiichiro , Abe Takeshi
Published: May 2020

Introduction

Fluoride shuttle battery (FSB), which uses fluoride ions as carrier ions, has attracted much attention as one of the innovative batteries that can theoretically exceed the energy density of conventional lithium-ion batteries. However, there are still few reports on charge/discharge reactions using fluoride ions as carriers[1, 2], and most of the electrode reactions are still unclear. Here we have applied the newly developed operando hard X-ray photoelectron spectroscopy (HAXPES) to a thin film Cu-based all-solid-state FSB, which allows us to observe the bulk-sensitive electronic structure changes in all the components (positive and negative active materials, a solid electrolyte and a current collector) during charge and discharge processes.

Experimental

A Cu positive electrode was deposited on a LaF3 substrate by a DC magnetron sputtering method, and an Au current collector was deposited thereon by the same method. A W current collector for the anode side was deposited on the back side of the LaF3 substrate by the same method. Electrochemical tests were performed with a constant current mode under potential rages from 3.6 V to 2.0 V at 140⁰C. The Au 4f, F 1s, La 3d, Cu 2p
operando HAXPES measurements was performed at BL28XU in SPring-8 during the charge process.

Results and Discussion

Fig. 1 shows the Cu 2p
3/2, F 1s and La 3d
5/2
operando HAXPES spectra at each charge capacity. The Cu 2p
3/2 HAXPES spectra were normalized with a peak intensity of 932.5 eV derived from Cu metal. As charging progressed, new peaks derived from CuF2 appeared at 936.8 eV and 943.0 eV, indicating that Cu converts to CuF2. In the F 1s and La 3d
5/2 HAXPES spectra, a peak shift of approximately 1.4 eV toward the lower binding energy was observed at the beginning of charging. These peak shifts correspond to the sudden increase in the cell voltages at the beginning of charging, indicating that a potential difference is generated between the LaF3 solid electrolyte and Cu positive electrode. As the charging reaction further proceeds, the peak shifts to the lower binding energy as the cell voltage increases in the La 3d
5/2 region, however, a new peak appeared at 684.7 eV to the higher binding energy in the F 1s region, suggesting that F species of CuF2 have been detected. Therefore, we succeeded in capturing the fluorination process of Cu by both Cu 2p and F 1s HAXPES spectra changes and the potential distribution of the all-solid-state FSB using operando HAXPES.

Acknowledgments

This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) under the “Research and Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING2)”.

References

[1] M. A. Reddy et al., J. Mater. Chem.
21, 17059 (2011).

[2] D. T. Thieu et al., Adv. Funct. Mater.
27, 1701051 (2017).

Figure 1
Study of Solid State Lithium Batteries with a Ceramic Electrolyte
Authors: Dussart Thibaut , Laberty-Robert Christel , Stevens Philippe , Toussaint Gwenaëlle
Published: May 2020

Solid state lithium batteries are considered as the next generation of batteries due to its potential higher energy density and better safety compared to Li-ion technology[1]. Oxides, sulfides, polymers and polymer/ceramic hybrid materials can be used as lithium ion conducting solid electrolytes, some of which have very good ionic conductivities (up to 10-3 S.cm-1 at 25°C) and good electrochemical stability[2,3].

Li1,3Al0,3Ti1,7(PO4)3 (LATP) is a potential candidate as a solid electrolyte with an ionic conductivity of 1.10-4 S.cm-1 at 25°C. It is stable up to 5V vs Li/Li+ but it is instable in contact with lithium due to the reduction of Ti4+ in Ti3+ [4]. A thin protective layer of a stable lithium ion conducting material is deposited to avoid contact between LATP and Li metal[5]. The LATP solid electrolyte has been synthesized via solid state synthesis and LATP particles exhibit a cubic morphology.

Al doped Li7La3Z2O12 (LLZO), another good candidate for solid electrolyte, displays a high ionic conductivity >10-4 S.cm-1 [6] and an good stability in contact with lithium metal. LLZO synthesized by the Pechini route exhibit a cubic phase with minor impurity of La2Zr2O7.

The main challenge is to control this interphase in order to decrease the interfacial resistance. Different strategies are employed to deposit the lithium such as electrochemical deposition and vapor deposition. Full cells are assembled using different positive electrode compositions and characterized in order to overcome the technological barriers related to this technology.

[1] T. Placke, R. Kloepsch, S. Dühnen, M. Winter, Lithium ion, lithium metal, and alternative rechargeable battery technologies: the odyssey for high energy density, J. Solid State Electrochem. 21 (2017) 1939–1964. doi:10.1007/s10008-017-3610-7.

[2] J. Janek, W.G. Zeier, A solid future for battery development, Nat. Energy. 1 (2016) 1–4. doi:10.1038/nenergy.2016.141.

[3] Y. Zhu, X. He, Y. Mo, Origin of Outstanding Stability in the Lithium Solid Electrolyte Materials: Insights from Thermodynamic Analyses Based on First-Principles Calculations, ACS Appl. Mater. Interfaces. 7 (2015) 23685–23693. doi:10.1021/acsami.5b07517.

[4] P. Hartmann, T. Leichtweiss, M.R. Busche, M. Schneider, M. Reich, J. Sann, P. Adelhelm, J. Janek, Degradation of NASICON-type materials in contact with lithium metal: Formation of mixed conducting interphases (MCI) on solid electrolytes, J. Phys. Chem. C. 117 (2013) 21064–21074. doi:10.1021/jp4051275.

[5] H.S. Kim, Y. Oh, K.H. Kang, J.H. Kim, J. Kim, C.S. Yoon, Characterization of Sputter-Deposited LiCoO 2 Thin Film Grown on NASICON-type Electrolyte for Application in All-Solid-State Rechargeable Lithium Battery, ACS Appl. Mater. Interfaces. 9 (2017) 16063–16070. doi:10.1021/acsami.6b15305.

[6] R. Murugan, V. Thangadurai, W. Weppner, Fast lithium ion conduction in garnet-type Li7La 3Zr2O12, Angew. Chemie - Int. Ed. 46 (2007) 7778–7781. doi:10.1002/anie.200701144.

Figure 1
(Invited) Systematic Study of Electrolyte Components and Their Effects on the Fast Charging of High Energy Density Li-Ion Cells
Authors: Wu Xianyang , Du Zhijia
Published: May 2020

Energy density, cost and safety are, more than ever, the most significant barriers to overcome in order to increase the wide acceptance of Li-ion batteries (LIBs) in electric vehicles (EVs).1 The U.S. Department of Energy (DOE) has set ultimate goals for battery electric vehicles (BEVs), which include reducing the production cost of the battery pack to $150/kWh, increasing the electrical range of the battery to 300 miles, and decreasing the charging time to 15 minutes or less.2 Increasing electrode thickness, and hence increasing active material loading, is an effective way to achieve these energy density and cost targets.3 The caveat, however, is that thicker electrodes fail during fast charging.

One of the solutions for enabling extreme fast charging while retaining most of the battery energy can be achieved through the significant enhancement of the Li-ion mass-transport in electrolytes such that enough Li ions are available for intercalation in graphite. The mass transport of Li-ions can be evaluated by two macroscopic characteristic values: 1) the Liions ionic conductivity that is related to the total flux of charge carriers, 2) the Liion transference number that is related to the fraction of the total current that is carried by Liions. An electrolyte with both higher Liions conductivity and transference numbers is ideal for higher Liions transport, and hence would be a step toward realizing cells with higher charging rates.

The fast charging performance of high-energy density (NMC811/graphite) Li-ion cells is studied when different electrolytes were used. The effect of electrolyte components and their effect of the electrode materials, electrolytes and electrolyte/electrode interfaces were studied and will be presented.

(1) Needell, Z. A.; et al. Potential for Widespread Electrification of Personal Vehicle Travel in the United States. Nat. Energy
2016, 1 (9).

(2) Howell, D.; et al. Enabling Fast Charging: Enabling Fast Charging: A Technology Gap Assessment. 2017, No. October.

(3) Du, Z.; et al. Understanding Limiting Factors in Thick Electrode Performance as Applied to High Energy Density Li-Ion Batteries. J. Appl. Electrochem.
2017, 47 (3), 405–415.
Impact of Solvation Energetics on the Oxygen Reduction Reaction in Alkali-Metal/Oxygen Batteries
Authors: Sankarasubramanian Shrihari , Ramani Vijay
Published: May 2020

Alkali-metal/Oxygen batteries are a potential high-energy alternative to Li-ion batteries1. In these systems, the critical performance bottleneck is the oxygen reduction reaction (ORR) which in turn depends on the non-aqueous electrolyte that mediates ion and oxygen transport2. Herein, we show that a multifold increase of the practical discharge power of these batteries can be achieved by tuning the tripartite interactions between the salt cation, anion and the solvent in the electrolyte3. A single descriptor of the solvation energetics, the solvent reorganization energy (λ), is shown to capture the influence of electrolyte composition on both reactant transport (DO2
) and reaction kinetics (k) at the electrode and found to be broadly applicable to alkali-metal/oxygen (i.e. Li-, Na- and K-O2) batteries. Increasing cation size (from Li+ to K+) doubled k/λ, indicating an increased sensitivity of k to the choice of anion, while variations in DO2
were minimal over this cation size range. These multifarious effects were captured in the Electrochemical Thiele Modulus incorporating Marcus-Hush kinetics and guidelines are presented for the choice of electrolyte solvent and salt when designing systems for high discharge rates. In a model symmetric K-O2 cell4, both the formation of solvent-separated ion-pairs and the existence of unsolvated anions reduced overpotential losses by 200mV compared to electrolytes with partial anion solvation, successfully demonstrating the rational, ab-initio design of electrolytes for high-power alkali-metal/Oxygen batteries.

References

1. N. Xiao, X. Ren, W. D. McCulloch, G. Gourdin, and Y. Wu, Acc. Chem. Res., 51, 2335–2343 (2018).

2. S. Sankarasubramanian, J. Seo, F. Mizuno, N. Singh, and J. Prakash, J. Phys. Chem. C, 121, 4789–4798 (2017).

3. S. Sankarasubramanian, J. Kahky, and V. Ramani, Proc. Natl. Acad. Sci. U. S. A., 116, 14899–14904 (2019).

4. S. Sankarasubramanian and V. Ramani, J. Phys. Chem. C, 122, 19319–19327 (2018).
Catalytic and Stability Performance of the Electrode and Electrolyte in Na-O2 Batteries: Electrochemical Insight
Authors: Hasan Maksudul , Ravikumar Ravikumar , Mamlouk Mohamed , Scott Keith
Published: May 2020

Using a metal anode in a metal air battery should maximise the cell voltage and energy density compared to the counterpart metal-ion technology but currently is challenging [1]. In sodium and lithium air batteries sodium or lithium dendrite formation at the anode is problem both in terms of performance and safety [2]. Oxygen (O2) may also diffuse to the anode and partly passivate the metallic surface and increase the cell impedance [2]. Side reactions of the metallic anode with the liquid electrolyte, O2 can also take place at the anode surface [3].

Here, we report how the Na anode, the cathode and electrolyte limit the performance of Na-O2 batteries. The capacity limitation of the Na-O2 batteries not only relates to air blockage of the cathode by the discharge products but also to the metallic anode due to its side reactions with electrolyte and O2. A pX logged cyclic voltammetry studies showed that metallic Na is passivated significantly in aerated electrolyte as indicated by a shift in the Na/electrolyte interface's oxidation and reduction reaction potential to both positive and negative directions. Consequently, the overall cell potential decreases while the charging over potential increases (Fig. 1). The isolation by a solid-state electrolyte of the metallic anode from the direct contact of liquid electrolyte and O2 resulted in a long operating time with cell potential close to the theoretical value. A high stability was achieved at slower charge-discharge rates due to lower ionic conductivity of the solid-state electrolyte at room temperature. We will examine a number of solid-sate electrolytes for high performance Na-O2 batteries. This study will also analyse ex situ characterisation of the products formed at the metallic Na/electrolyte and non-precious metal oxide air-cathode/electrolyte interfaces that correlates the catalytic and stable performances of Na-O2 batteries.

References:

1. L. J. Hardwick and C. P. de Leon, Johnson Matthey Technology Review, 62, 134 (2018).

2. B. Sun, C. Pompe, S. Dongmo, J. Q. Zhang, K. Kretschmer, D. Schroder, J. Janek and G. X. Wang, Advanced Materials Technologies, 3 (2018).

3. I. Landa-Medrano, C. Li, N. Ortiz-Vitoriano, I. Ruiz de Larramendi, J. Carrasco and T. Rojo, Journal of Physical Chemistry Letters, 7, 1161 (2016).

Figure: CV’s in TEGDME containing 0.5 M NaFSI with N2 and O2 saturated; catalyst loading 1.5 mg cm-2 and scan rate 10 mV s-1. Three-electrode glass cell using Na foil wire as the counter, Ag/AgCl as the reference and Ni/TiC/NiCo2O4 as the working electrode were used. The counter electrode potential was measured vs Ag/AgCl using pX data logger.

Figure 1
Towards Moisture Tolerant Aprotic Lithium-air Batteries via Reversibly Cycling LiOH
Authors: Temprano Israel , Liu Tao , Petrucco Enrico , Kim Gunwoo , Ellison James , Jónsson Erlendur , Grey Clare P.
Published: May 2020

In the light of recent commitments from several European countries to ban the sale of internal combustion engine vehicles in the coming decades, the race to develop electrical storage strategies beyond the capabilities of lithium ion batteries is intensifying considerably. Amongst the many different options, Li-air batteries (LABs) have attracted significant attention due to their comparable energy density to fossil fuels1. Despite of its potential, several fundamental challenges remain to be overcome for their successful development2-4. Amongst these challenges, the instability of the typical discharge products (LiO2 and Li2O2) in the presence of moisture and CO2 represents a fundamental stumbling block5.

The development of moisture-tolerant, LiOH-based non-aqueous Li-O2 batteries is a promising route to bypassing the inherent limitations caused by the instability of their typical discharge products6. The use of the I-/I3
- redox couple to mediate the LiOH-based oxygen reduction and oxidation reactions has proven challenging to develop due to the multiple reaction paths induced by the oxidation of I- on cell charging7. In this work we demonstrate a reversible LiOH-based Li-O2 battery cycling through a 4 e-/O2 process with low charging overpotential (below 3.5 V vs Li/Li+). This is achieved by increasing the oxidizing power of I3
-, which shifts the charging mechanism from IO-/IO3
- formation to O2 evolution.

1. C. P. Grey and J. M. Tarascon, Nature Materials, 2017, 16, 45–56.

2. G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson and W. Wilcke, The Journal of Physical Chemistry Letters, 2010, 1, 2193-2203.

3. D. Aurbach, B. D. McCloskey, L. F. Nazar and P. G. Bruce, Nature Energy, 2016, 1, 16128.

4. D. G. Kwabi, N. Ortiz-Vitoriano, S. A. Freunberger, Y. Chen, N. Imanishi, P. G. Bruce and Y. Shao-Horn, MRS Bulletin, 2014, 39, 443-452.

5. N. Mahne, B. Schafzahl, C. Leypold, M. Leypold, S. Grumm, A. Leitgeb, Gernot A. Strohmeier, M. Wilkening, O. Fontaine, D. Kramer, C. Slugovc, Sergey M. Borisov and Stefan A. Freunberger, Nature Energy, 2017, 2, 17036.

6. T. Liu, M. Leskes, W. Yu, A. J. Moore, L. Zhou, P. M. Bayley, G. Kim and C. P. Grey, Science, 2015, 350, 530-533.

7. C. M. Burke, R. Black, I. R. Kochetkov, V. Giordani, D. Addison, L. F. Nazar and B. D. McCloskey, ACS Energy Letters, 2016, 1, 747-756.

Figure 1
Understanding the Interplay between Li Intercalation and Li Plating Using Single Graphite Particle Electrochemistry
Authors: Gao Tao , Chueh William C. , Li Ju , Bazant Martin Z.
Published: May 2020

Potential safety hazard of lithium ion batteries, their long recharging time and performance degradation during usage are the major obstacles that prevent the wide adoption of electric vehicles in our society. Lithium plating on graphite anode is considered the leading cause of thermal runaway, degradation and the barrier for fast charging. However, the onset of lithium plating on graphite anodes is not well understood. For the first time, we resolved the spatial dynamics of lithiation of a single graphite particle using in-situ optical microscopy, and shed light on the interplay between lithium intercalation and plating. Enabled by simultaneously monitoring of the voltage, phase transformation and lithium plating, we are able to elucidate the energetics and kinetics of the two competing reactions, and establish a comprehensive mechanistic picture of Li plating mechanism on graphite anode. The proposed mechanism was further validated by simulation using a 1-D phase field model. This work is therefore providing insights on guidelines of designing graphite anode and operating LiB for reducing the risk of lithium plating.
Effective Property Uncertainty of Graphite Electrodes from Computed Tomography Using Bayesian Convolutional Neural Networks
Authors: Norris Chance , LaBonte Tyler , Martinez Carianne , Roberts Scott A. , Mukherjee Partha P.
Published: May 2020

In recent years there have been great advances in using 3D tomography in battery research, providing the ability to see as-manufactured electrodes at the mesoscale. These structures are subsequently used to find effective properties or perform detailed electrochemical simulations. A key step of this analysis is image segmentation, which differentiates particle and void phases. Image segmentation, however, is painstaking and fraught with subjectiveness. Removing this subjectiveness is paramount in having credible direct numerical simulations to bridge the gap of the computational and experimental regimes. To improve the image segmentation process and quantify its uncertainty, a Bayesian convolutional neural network (BCNN) is implemented to segment greyscale tomograms of graphite electrodes. The use of a BCNN allows for native and explainable uncertainty estimates. Two manually segmented tomograms were used to train the BCNN, which was in turn used to segment an additional four tomograms. This process was effective in creating high quality binary stacks, which in some cases presented a subjectively superior segmentation compared to the manual process. Additionally, BCNN-generated uncertainty estimates provide a range of possible image segmentations and structures. These nominal and uncertainty ranged structures are propagated through simulations of effective electrical conductivity and pore phase tortuosity, providing both nominal property predictions and geometric uncertainty estimates of those predictions. This work demonstrates a new method for quantifying geometric uncertainty from as-manufactured electrode images and the impact of that uncertainty regarding battery-relevant physical phenomena.