bluuebunny/crossref_metadata_2025 huggingface dataset:
The Enhancement Effect of Borate Doping on the Oxygen Evolution Activity of α-Nickel Hydroxide
Authors: Zhang Zhao , Zhang Tianran , Lee Jim Yang
Published: February 2020

ABSTRACT:

The availability of low-cost, high-efficiency oxygen evolution catalysts is pivotal to the application of renewable energy conversion and storage systems based on solar energy and water splitting reactions. We demonstrate here that a moderate amount (~12 wt%) of borate doping of crystalline α-Ni(OH)2, a common low-cost catalyst, can lower the Tafel slope of the oxygen evolution reaction (OER) from the typical value of 60 mV decade-1 to 43 mV decade-1; and the overpotential for 10 mA cm-2 of current density from 390 mV to 340 mV in 0.1 M KOH aqueous solution. Borate doping also improves the stability of α-Ni(OH)2 in OER. The borate-doped α-Ni(OH)2 can even surpass the reference Ir/C precious metal catalyst in both activity and stability. These results here highlights the potential of borate doping as a promising strategy to increase the catalytic activity of base metal in water oxidation catalysts.

Figure Caption:

a). Cyclic voltammograms of OER on borate-doped α-Ni(OH)2 (denoted as B-NOH), α-Ni(OH)2 (denoted as NOH), and Ir/C

b). The volcano curve of OER overpotential as a function of the boron content of B-NOH

c). The proposed mechanism on a borate-coordinated Ni active center.

Figure 1
A Bifunctional Electrocatalyst for Full Water Splitting: CoNi@BSCF Encapsulated in N-Doped Carbon
Authors: Lyu Yuqi , Ciucci Francesco
Published: February 2020

Oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are two half reactions of full electrochemical water splitting, which is a promising solution to produce hydrogen, a clean and renewable energy carrier to replace fossil fuels. Up to now, the benchmark catalysts for OER and HER are noble metal based materials, such as IrO2 and Pt/C. However, the scarcity, extremely high cost, and poor stability of these noble metals highly limit their large-scale commercialization. Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), a perovskite material with cubic structure, has been recognized as one of the most promising OER catalysts to replace noble metals. The excellent OER activity of BSCF is partially due to its high oxygen vacancy content, which, however, leads to a relatively poor operation stability. As to HER, BSCF also shows superior performance in comparison to other oxide catalysts, but still far from comparable to Pt/C.

Herein, we report a facile way to enhance the operation stability as well as the HER and OER activity of BSCF. Through hydrothermal preparation and mechanical ball milling, we obtained a three-layer composite containing BSCF particles, CoNi nanoparticles, and N-doped carbon. With the protection of carbon shell, this composite, CoNi@BSCF/NC, displays a significant enhanced stability in both OER and HER in comparison to BSCF in alkaline media. The OER activity of CoNi@BSCF/NC is much higher than that of BSCF, including a smaller onset potential (by 30 mV) and a smaller overpotential at 10 mA/cm2 (by 72 mV). More interestingly, this composite displays a self-improvement in OER activity during CV test, while BSCF shows obvious activity decay upon CV cycle numbers. This is mostly due to (i) the gradually oxidation of Ni in CV process, (ii) the protection of carbon shell, and (iii) the synergistic effect of BSCF and CoNi nanoparticles. Moreover, the HER activity of CoNi@BSCF/NC is also greatly improved with a small onset potential, which is 180 mV smaller than BSCF. Furthermore, CoNi@BSCF/NC also shows an excellent performance in full water splitting with our homemade electrolyzer, with a small overpotential at 10 mA/cm and good operation stability. Our study shows that CoNi@BSCF/NC is one of the best OER catalysts reported so far and among the best perovskite-based HER catalysts. This work may open new opportunity to further enhance the activity and operation stability of some state-of-the-art catalysts, such as BSCF.
Nickel Electrocatalyst Promoted By Lace Oxide on Carbon Support for Hydrogen Evolution Reaction in Alkali Media
Authors: Jang Myeong Je , Park Yoo Sei , Choi Woo Sung , Choi Sung Mook , Lee Kyu Hwan
Published: February 2020

In this work, we present a mass production method of nano-sized Ni catalyst using late transition metal oxides La2O3 and CeO2 as promoters on a carbon support. The Ni­­_La0.67Ce0.33O1.67/C catalyst was synthesized by co-precipitation for La0.67Ce0.33O1.67 and solvo-thermal for Ni, which are an easy method and capable of making higher activity and durability catalysts. La0.67Ce0.33O1.67 plays an important role in decreasing the size of the Ni particles and helps to improve the properties of the catalyst in reducing atmosphere by forming a solid solution. The Ni_La0.67Ce0.33O1.67/C catalyst recorded a lower overvoltage of 124 mV at a current density of 10 mA/cm2 and a higher long-term stability in 1 M KOH solution at room temperature compared to the Ni/C catalyst. It is suggested that La0.67Ce0.33O1.67 forms a partial alloy with Ni to prevent the detachment of Ni and acts as a barrier to prevent the migration of Ni. Based on the results of this study, a mechanism of Ni catalyst degradation was proposed.
Effect of Co-Generated MoO3 on the Electrocatalytic Hydrogen Evolution Performance of O2 Plasma Modified MoS2
Authors: Zhang Chengxu , Jiang Lin , Hu Jue , Leung Michael K.H. , Zhang Yingjie
Published: February 2020

Extensive efforts have been devoted to developing MoS2 nanostructures to maximize the number of active edge sites [1], but little attention has been paid to simultaneously tailoring of both the edge and planar structure itself for enhancing the HER kinetics. In this work, we used the one-step O2 plasma modification to simultaneously engineer the edge and planar structure of MoS2 to fabricate the high-performance MoS2 electrocatalyst with defect-rich edge and oxygen-doped planar structure. We further notice that the influence of the inevitably generated MoO3 species on the HER activity and stability of MoS2 and its structure changes after long-term electrocatalytic reaction, which are significant to understand the HER electrocatalysis on the O-incorporated MoS2 catalysts, however, are still unknown [2]. Herein, controlled plasma exposure time has been designed to explore the influence of MoO3 species on the HER performance of O2 plasma modified MoS2 catalysts. We find that the MoO3 species in MoS2 are not conductive to the HER electrocatalysis. More importantly, these co-generated MoO3 species are reduced and resolved from the MoS2 lattice during the electrocatalytic hydrogen evolution, leading to a holey structure in the MoS2 nanosheets and thus a significant improvement of its hydrogen evolution stability (Figure 1a). This work is the first to explore the Janus effect of O2 plasma modification on MoS2 for acceleration the hydrogen evolution reaction, and opens a new way to developing layered materials for electrochemical energy applications. Aside from the fundamental insight attained from the rational materials design, the MoS2 O2-plasma 60s catalyst exhibits a boosted HER activity with the overpotential as low as 131 mV at the current density of 10 mA/cm2 and striking long-term durability, better than most reported MoS2-based catalysts (Figure 1b).

Figure captions

Figure 1. (a) Polarization curves recorded from the MoS2 O2-plasma 60s catalyst at a scan rate of 5 mV/s before and after the chronopotentiometry test. Inset: chronopotentiometry responses (η ~ t) recorded at a constant current density of -10 mA/cm2. (b) TEM image of the MoS2 O2-plasma 60s sample after the chronopotentiometry test at -10 mA/cm2 for 20 hours.

References

[1] Hu J, Huang B, Zhang C, Wang Z, An Y, Zhou D, et al. Engineering stepped edge surface structures of MoS2 sheet stacks to accelerate the hydrogen evolution reaction. Energy Environ Sci. 2017;10:593-603.

[2] Tao L, Duan X, Wang C, Duan X, Wang S. Plasma-engineered MoS2 thin-film as an efficient electrocatalyst for hydrogen evolution reaction. Chem Commun. 2015;51:7470-3.

Figure 1
Ruthenium Cobalt Phosphide Hybrid Clusters with Exceptional Hydrogen Evolution Performance in Both Acidic and Alkaline Electrolytes
Authors: Liu Lifeng , Xu Junyuan
Published: February 2020

The hydrogen evolution reaction (HER) is crucially important for water splitting, for which platinum (Pt) has been considered the state-of-the-art electrocatalyst. Despite recent progress in non-Pt electrocatalysts, few Pt-free catalysts can compete against Pt in terms of HER activity particularly in alkaline solution. Here, we report a new efficient Pt-free HER catalyst – hybrid ruthenium cobalt phosphide (RuCoP) cluster where Ru exists in metallic chemical state in the hybrid. The unique hybridization allows electron transfer to take place from both Co and P to Ru, thereby significantly enhancing the hybrid’s HER activity. The as-synthesized RuCoP clusters demonstrate a considerably low overpotential (η) of 11 mV at -10 mA cm2 and a high turnover frequency (TOF) of 5.64 s-1 at η = 100 mV in 0.5 M H2SO4. Remarkably, even in alkaline solution (1.0 M KOH) the excellent HER performance of RuCoP remains, with a very low η
10 of 23 mV and exceptionally high TOF value of 3.85 s-1 at η = 100 mV. Moreover, the RuCoP catalysts show outstanding catalytic stability toward the HER in both acidic and alkaline solutions, superior to that of commercially available Pt/C catalysts.

Figure 1
(Invited) Water Adsorption on Transition Metal Oxide Pure IrO2, RuO2 and Alloy RuxIr1-XO2(110) Surfaces Investigated By Density Functional Theory
Authors: Oliveira Luiz , Franco Alejandro A. , Loffreda David
Published: February 2020

RuO2 and IrO2 are the most used catalyst materials for water electrolysis in the anode electrode of the so-called polymer electrolyte membrane water electrolyzers (PEMWE), the former presents higher activity and the latter a higher resistance to corrosion. Therefore alloys, RuxIr1-xO2, have been proposed in order to enhance the stability of the anode electrode without affecting its activity. However, up to date, the origins of such an improvement are not elucidated. In this article, we propose to progress on that question by exploring the adsorption properties of one water molecule on model surfaces of RuO2(110), IrO2(110) and RuxIr1-xO2(110) from density functional theory (DFT) calculations. The manuscript details several initial structures of water molecule above the metal oxide surfaces. Energetics of adsorption of water on those oxide surfaces is presented and compared, as well as magnetic properties of these systems, an element which is rarely detailed in the corresponding literature. In particular, the role of the second metal in the alloy oxide surface on the adsorption properties is addressed by playing with the relative surface composition between Ru and Ir and alloying structure. For a substantial content of Ir in the surface of RuO2(110) (1D model), our DFT results show that the adsorption properties are similar to those on pure RuO2(110). This means that these particular mixed oxide surfaces should exhibit an equivalent activity than the one on pure RuO2(110), and in the same time, a larger resistance to corrosion due to the presence of Ir.

This work is a prerequisite towards a systematic investigation of the adsorption of intermediate species for the oxygen evolution reaction (OER) on model surfaces of the aforementioned materials.
A Spatially-Reduced Dynamic Thermal Model for Liquid Cooling Lithium-Ion Battery Pack
Authors: Dan Dan , Zhang Yangjun
Published: February 2020

In electric vehicles, thermal management of a battery pack is becoming critical as both excessive and low temperature may affect the overall battery life and even trigger disastrous damage to a battery pack. Therefore, estimating the temperature distribution and its variation over time is an essential requirement to ensure safe and provide design guidance for control strategy.

This study carries out a transient thermal model to predict the thermal behavior of a square lithium-ion battery pack with liquid cooling thermal management system. Different from Equivalent thermal circuit (ETC) model, which can only predict a lumped temperature of a battery cell, a one-dimensional thermal model was built in this study to estimate the temperature distribution throughout the cell and its variation over time according to the structural feature and the liquid cooling mode.

The model is based on the Green function method, capable of calculating one-dimensional thermal dynamics and achieving high accuracy with low calculation requirements, making it suitable for real-time control. A second order equivalent circuit model was used in the approach to predict the dynamics of the cell voltage and SOC in relation with the current. Then the electric model is coupled with a lumped thermal model to describe the dynamics of internal temperature distribution of one cell. Based on this cell model, a coupled flow-electro-thermal model for a battery pack was built, which was able to predict the uneven heat generation during the charge and discharge procedure under different cooling conditions.

3D CFD calculation was conducted for the model calibration and validation results are presented to support the proposed modeling approach.
Using Local Volume Expansion to Design Better Charging Protocols for Lithium-Ion Batteries
Authors: Spingler Franz B. , Wittmann Wilhelm , Sturm Johannes , Jossen Andreas
Published: February 2020

Introduction

Reduction of charging time is desirable in most battery-powered applications and may be a key factor for wider acceptance of battery electric vehicles (BEVs). However, fast charging of lithium-ion cells may result in accelerated aging [1]. In state-of-the-art cells, lithium deposition on the graphite anodes is a significant mechanism of capacity loss, especially with high charging rates and/or low temperatures.

In this work, we show that local cell expansion can serve as an indirect measure of lithium deposition and how this relationship can be used to design charging protocols that provide both beneficial battery cycle life and charging time.

Experimental and Results

A 2-D thickness scan setup [2] is used to measure locally resolved thickness changes of commercial pouch cells during operation. After accounting for thermal expansion, the thickness changes are linked to reversible and irreversible lithium plating. The analysis is underpinned by voltage relaxation [3] and post-mortem examination. It is shown that the locally resolved thickness measurement helps detect lithium deposition more reliably and at an earlier stage than a with single-spot or a surface-averaged thickness measurement.

Finally, a screening of charging conditions and corresponding thickness changes is performed. Fast charging protocols are derived based on maximum allowable local irreversible thickness change. An extended cycling experiment serves as a proof of the cycle life advantage of our fast charging protocols compared to standard constant current – constant voltage charging.

Acknowledgements

This work has received funding from the European Union's Horizon 2020 research and innovation programme under the grant 'Electric Vehicle Enhanced Range, Lifetime And Safety Through INGenious battery management' (EVERLASTING-713771).

References

[1] Sikha G, Ramadass P, Haran BS, White RE, Popov BN. Comparison of the capacity fade of Sony US 18650 cells charged with different protocols. Journal of Power Sources 2003;122(1):67–76.

[2] Rieger B, Schuster SF, Erhard SV, Osswald PJ, Rheinfeld A, Willmann C et al. Multi-directional laser scanning as innovative method to detect local cell damage during fast charging of lithium-ion cells. J. Energy Storage 2016;8:1–5.

[3] Zinth V, Lüders C von, Hofmann M, Hattendorff J, Buchberger I, Erhard S et al. Lithium plating in lithium-ion batteries at sub-ambient temperatures investigated by in situ neutron diffraction. J. Power Sources 2014;271:152–9.

Figure 1
Evaluation of Thick Electrode Architectures for High Energy Density Li-Ion Batteries
Authors: Wood Marissa , Li Jianlin , Wood David L , Daniel Claus , Dunlop Alison R , Polzin Bryant J. , Jansen Andrew N. , Krumdick Gregory
Published: February 2020

Thick electrodes have attracted considerable interest due to their potential role in achieving high energy density Li-ion batteries for electric vehicle applications. Incorporating thick electrodes eliminates many of the inactive separator and current collector layers that add cost, weight, and volume to the battery. However, mass transport of Li ions becomes a limiting factor at these dimensions and leads to poor rate capability at high charge and discharge rates. Different electrode architectures have been proposed to facilitate Li ion transport throughout the entirety of the electrodes, but the connection between structure and performance remains unclear. We used two different active material particle sizes to create thick anodes and cathodes (~4 mAh/cm2) with different structures and pore size distributions to determine the effect of architecture on electrochemical performance. Seven graphite anodes and seven NMC 532 cathodes were coated in various single- and double-layer configurations and assembled into single-layer pouch cells in forty-nine different cathode/anode combinations. These cells were then subjected to charge and discharge rate performance testing. We found that both particle size and structural arrangement have significant impacts on the resulting rate performance. Mercury porosimetry was performed on all electrodes to help correlate pore size distribution with performance. In addition, the best- and worst-performing cells were selected for post-mortem analysis to further understand the nature of the observed electrochemical differences. Our results demonstrate that the rate performance of thick electrodes can be improved by altering the electrode architecture. More precise control over the structure could lead to further improvements and enable the implementation of thick electrode Li-ion battery designs for cheaper, long-range electric vehicles.

Figure 1
Thermodynamic Model for Substitutional Materials. Application to Lithiated Graphite, Spinel Manganese Oxide, Iron Phosphate, and Layered Nickel-Manganese-Cobalt Oxide
Authors: Verbrugge Mark W , Baker Daniel R , Koch Brian J. , Xiao Xingcheng , Gu Wentian
Published: February 2020

We derive and implement a method to describe the thermodynamics of electrode materials based on a substitutional lattice model. To assess the utility and generality of the method, we compare model results with experimental data for a variety of electrode materials: lithiated graphite and layered nickel-manganese-cobalt oxide (Chevrolet Bolt Electric Vehicle negative and positive electrode materials, respectively), manganese oxide (in the positive electrodes of the Gen 1 and Gen 2 Chevrolet Volt Extended Range Electric Vehicle and the positive electrode of many high-power-density batteries), and iron phosphate (Gen 1 Chevrolet Spark Electric Vehicle positive electrode material and of immediate interest for 12 and 48 V applications). An early version of the model has been applied to lithiated silicon (Li-Si). As was found in the Li-Si study, the model enables one to quantitatively represent experimental data from these different electrode materials with a small number of parameters, and, in this sense, the approach is both general and efficient. An open question is the utility of controlled-potential vs. controlled-current experiments for the elucidation of the system thermodynamics. We provide commentary on this question, and we highlight other open questions throughout this work.
Modeling Chemical Heat Sources in Li-Ion Batteries for a Broader Range of Materials and Conditions
Authors: Shurtz Randy C. , Hewson John
Published: February 2020

Calorimetry data have been used over the past two decades to develop models of thermal decomposition of single Li-Ion cells that yield reasonable predictions of the onset of thermal runaway. However, predictions of cascading runaway in systems with many cells require models that capture the total heat release with greater fidelity. This work is targeted at extracting additional information from existing calorimetry and chemical composition data to model electrode decomposition processes occurring at higher temperatures. The updated thermochemical models include more rigorous dependence on materials properties to enable application to customized battery builds with better predictive capability than previous models. Comparisons of the models to experimental data yield insights that are not always obvious from comparisons of data alone.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

SAND2017-12560 C
A New, Generalized Electrolyte Donicity Model for Prediction of Reaction Pathways in Li-S Batteries
Authors: Zavadil Kevin R , Watkins Tylan S
Published: February 2020

Li-S batteries are plagued by parasitic reactions driven by soluble reaction intermediates resulting in stored energy loss and short cycle life. Electrolytes with low solubility limits for these lithium polysulfide (LiPS) intermediates reduce parasitic reactions, improving efficiency and life of cells. Sparingly solvating electrolytes drive sulfur reduction through a solid state pathway, potentially eliminating parasitic losses due to LiPS.1 Realizing the goal of electrolyte design to enhance cell performance requires a quantitative model of LiPS solubility.

Predicting LiPS Solubility with Electrolyte Donor Number (EDN):

Building on the Gutman Donor Number concept, this talk will describe a new way of thinking about donicity—from the perspective of multicomponent systems (i.e. electrolytes). First, it will be shown that 23Na NMR can be used as a technique for deriving a pseudo-Gutman DN (23Na-DN) for any given electrolyte composition. This is similar to work described by Schmeisser et al., in which DNs for ionic liquids were derived from 23Na NMR.2 Next, it will be shown that an accurate descriptor for LiPS solubility also requires knowledge of the density of total available donor sites within a given electrolyte. Raman spectroscopy was used to deduce the specific populations of both solvent and anion species (i.e. establishing the coordinating behavior of solvating species to Li+ ions in solution as a function of salt concentration). Finally, it will be shown that the complete descriptor for LiPS solubility, as determined experimentally, relies on both the 23Na-DN and the structural arrangements of Li+ coordinating ligands within a given electrolyte. The combination of these two characteristics establishes an “electrolyte donor number” (EDN). Figure 1 shows that LiPS solubility values converge to a single function versus different functions with respect to the EDN and DN, respectively.

Discussion on the Prediction of Reaction Pathways:

The EDN model predicts LiPS solubility well. Thus, it is not surprising that it also acts as a useful tool for predicting the electrochemical reaction pathways taking place in a Li-S cell. Figure 2 shows the discharge curves for tetraglyme-based electrolytes that span a maximum range of EDN values. It is clear from this data that a higher EDN drastically changes the observed voltage profile, and therefore the mechanistic pathway.

References:

Cheng, L.; Curtiss, L. A.; Zavadil, K. R.; Gewirth, A. A.; Shao, Y.;

Gallagher, K. G. ACS Energy Lett. 2016, 1, 503−509.

Schmeisser, M.; Illner, P.; Puchta, R.; Zahl, A.; Eldik, R. Chem. Eur. J. 2012, 18, 10969–10982.­­

Figure 1
Substituted LiCoPO4 As Cathode Material for Lithium Batteries
Authors: Allen Jan L , Delp Samuel A , Wolfenstine Jeff , Jow T Richard
Published: February 2020

LiFePO4 (LFP) as a Li cathode is known for its safety and good rate capability but its adoption has been limited by its low voltage of only 3.5V vs. Li+/Li. Replacement of Fe by Co leads to a 4.8V cathode and up to 40% higher energy density. Can we couple the promise of a safe phosphate system with a high energy density? The path towards using LiCoPO4 (LCP) as cathode is challenging. There is an inherent capacity fade observed for unsubstituted LCP cycling in conventional electrolyte owing to both cathode and electrolyte deterioration. The mechanical properties of LCP were studied and are similar to LFP and are thus not responsible for its capacity fade. LCP’s electrical conductivity is several orders of magnitude lower than LFP. In order to realize the promise of the LCP system we have addressed structural stability and electronic conductivity through substitutional chemistry, electrolyte reformulation and surface modification. Even a low level of Fe substitution into LCP increases the electrical and ionic conductivity and stabilizes the de-lithiated structure through change in the electronic structure which shift the redox activity toward the transition metal and away from oxygen. Substitution of Cr for Co further increases the redox activity of Co leading to higher discharge capacity than for Fe-only substituted LCP. This stabilization mechanism is confirmed through spectroscopic measurements, through DFT calculation and is evidenced by extremely reduced discharge capacity fade during electrochemical cycling. Addition of Si to the cathode reduces the reactivity with the electrolyte as evidenced by an increase in the coulombic efficiency. Electrolyte stability has been further addressed through sacrificial additives, changes in solvent composition and surface modification of LCP. This paper will discuss the most recent progress in the path towards use of LCP as cathode material in lithium batteries and the path forward.
(Invited) Bulk and Surface Chemistry of High-Nickel Layered Oxide Cathodes
Authors: Manthiram Arumugam
Published: February 2020

Lithium-ion batteries have become the choice of power source for portable electronics and electric vehicles as they offer higher energy density than other rechargeable systems. They are also being intensively pursued for grid storage of electricity produced from renewable sources like solar and wind. Cost, safety, cycle life, energy, power, and environmental impact are the major factors in adopting them for a specific application. Among the various practically viable insertion-compound cathode chemistries available, the layered LiMO2 (M = Mn, Ni, Co, and their solid solutions) oxides offer the highest energy density. Accordingly, there is immense interest in both academia and industry in increasing the charge-storage capacities of the layered oxide cathodes beyond the current levels. In this regard, layered oxide cathode compositions with higher nickel contents (> 50 %) are drawing much attention in recent years since Ni offers higher capacity than Co as Ni3+ can be oxidized fully to Ni4+ without releasing oxygen from the lattice unlike Co3+, which can be oxidized only to ~ 3.5+ to avoid oxygen release from the lattice. Unfortunately, compositions with high Ni contents suffer from (i) multiple phase transitions, resulting in volume change and internal stress and (ii) high surface reactivity with the organic liquid electrolyte, resulting in a growth of cell impedance and fast capacity fade during cycling. They also suffer from high surface reactivity with ambient air to form lithium hydroxide and lithium carbonate on the particle surface, which not only degrades the electrochemical performance but also severely hampers the electrode fabrication process. Innovative approaches to overcome the above challenges are needed to employ high-nickel layered oxide cathodes in practical lithium-ion cells.

This presentation will focus first on developing a fundamental understanding of the factors that control the capacity fade and air-reactivity of high-nickel layered oxide cathodes, employing samples with secondary particle sizes of ~ 10 microns and advanced bulk and surface characterization methodologies. In-depth understanding obtained with high-nickel layered oxide cathodes with Ni contents of as high as 94% and graphite anodes retrieved from full cells before and after 1,000 – 3,000 cycles based on a combination of characterization techniques, viz., X-ray photoelectron spectroscopy (XPS), time-of-flight – secondary ion mass spectroscopy (TOF-SIMS), and high-resolution transmission electron microscopy (TEM), will be presented. Utilizing the understanding gained, the presentation will then focus on the design and development of layered oxide compositions with controlled bulk and surface structures as well as new electrolytes that offer a robust interface with both the graphite anode and high-nickel layered oxide cathodes will be presented. Viability to realize lithium-ion cells with cathode capacities of as high as ~ 220 mAh/g, high power capability, and high volumetric energy density will be discussed.
Tuning the Adsorption of Polysulfides(Li2Sx) in Lithium-Sulfur Batteries with Metal-Organic Frameworks(MOFs)
Authors: Park Haesun , Siegel Donald J
Published: February 2020

The dissolution of polysulfide (PS) intermediates during discharge is a well-known obstacle to achieving long cycle-life in lithium-sulfur batteries. Prior work has shown that PS dissolution can be partially suppressed via physical encapsulation of sulfur and PS within a porous cathode support. Metal-organic frameworks (MOFs) are crystalline, nanoporous materials with extremely high surface areas, whose structure and composition can be varied extensively. MOFs are promising cathode support materials because the encapsulation afforded by MOF pores can be augmented by chemical adsorption of PS onto coordinately unsaturated metal sites (CUS). Here we demonstrate that this additive approach – restricting PS dissolution by combining encapsulation and adsorption within a MOF – can be tuned to maximize PS anchoring via metal substitution on the CUS. Optimal MOF compositions are pinpointed by computationally screening 16 metal-substituted variants of M2(dobdc) (MOF-74) for their ability to chemically anchor prototypical species (S8, Li2S4, and Li2S) present during the cycling of Li-S batteries. Ti2, Ni2, and Mo2(dobdc) are identified as the compositions with the largest affinities for Li2S4 and Li2S. As Ni2(dobdc) has been synthesized previously, this MOF is proposed as a promising cathode support for Li-S batteries.

[1] R. Demir-Cakan et al., J. Am. Chem. Soc., 133, 16154 (2011)

[2] J. Zheng et al., Nano
Lett., 14, 2345 (2014).

[3] H. Park and D. J. Siegel, Chem. Mater., 29(11), 4932 (2017)
(Invited) Progress in Gradient Cathode Materials for High-Performance Rechargeable Lithium-Ion Batteries
Authors: Sun Yang-Kook
Published: February 2020

High-energy-density rechargeable batteries are needed to fulfill various demands such as self-monitoring analysis and reporting technology (SMART) devices, energy storage systems, and (hybrid) electric vehicles. As a result, high-energy electrode materials enabling a long cycle life and reliable safety need to be developed. To ensure these requirements, new material chemistries can be derived from combinations of at least two compounds in a secondary particle with varying chemical composition and primary particle morphologies having a core−shell structure and spherical cathode-active materials, specifically a nanoparticle core and shell, nanoparticle core and nanorod shell, and nanorod core and shell. To this end, several layer gradient cathode materials were developed to ensure high capacity, reliability, and safety. One of the most promising oxides is full concentration gradient (FCG) lithium nickel-cobalt-manganese oxide composed of a Mn-rich outer surface providing excellent safety and Ni-rich center achieving high capacity. In addition, we extended the FCG concept and report a new novel Li[NixCoyMnz]O2 cathode material with two-sloped full concentration gradients (TSFCG) of Ni, Co, and Mn ions throughout the cathode particles to maximize the average Ni concentration at the core as active redox species and the Mn concentration in the area near the particle surface. Comparison of electrochemical and thermal properties of the TSFCG with those of NCA and conventional cathode Li[NixCoyMnz]O2 is presented.
In Operando Depth Profiling Studies of Thick NMC Cathodes
Authors: Khalifah Peter , Li Zhuo , Yin Liang , Mattei Gerard , Lee Byoung-Sun , Wu Zhaohui , Bak Seong-Min , Yang Xiao-Qing , Liu Ping
Published: February 2020

In order to understand the nature of their transport limitations, thick NMC cathodes have been studied in operando using synchrotron radiation. From this data, the state of charge (SOC) of cathode films were determined with high spatial and temporal resolution, allowing the behavior at different heights within the film to be independently followed. A number of unexpected phenomena present in the cycling data will be discussed.
Investigation of Degradation Pathway in High Ni-Content Cathode Materials at Primary and Secondary Particle Level By Multi-Scale Characterization
Authors: Lin Ruoqian , Bak Seong-Min , Lee Hung-Sui , Yang Xiao-Qing , Xin Huolin L.
Published: February 2020

There is an increasing interest in studying the high Ni-content layered oxide materials for Li-ion batteries, especially for their application in electrical vehicles, since they are promising candidates for next-generation energy storage materials. Compared to traditional layered oxide materials such as LiCoO2 (LCO) or LiNi1/3Mn1/3Co1/3 O2 (NMC333), high Ni-content materials can provide higher specific capacity and energy density due to the two electron transfer per Ni by the Ni2+/Ni4+ redox couple. However, these materials are still suffering from the problems of capacity fading. It is quite important to understand the relationship between performance deterioration and structural degradation. The in-depth understanding of such relation can provide valuable guidance for future material design. The results obtained from our newly developed multi-scale characterization techniques will be reported, including the state-of-the-art aberration-corrected scanning transmission microscopy (STEM) imaging, STEM-electron energy loss spectroscopy (EELS), X-ray imaging, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). These results show that such multi-scale combined characterization tools can help us to study the formation of internal nano-pore structure at primary particle level and understand its impact on the formation of micro-cracks at secondary particle level. This structure degradation is highly correlated to the irreversible cation migration and intermixing at atomic level during extensive electrochemical cycling. Also, we found that the surface plays a vital role in the function of these materials. By combining the synchrotron based X-ray techniques with electron microscopy and spectroscopy, this presentation will report the degradation pathway of high Ni-content cathode materials for Li-ion batteries.
Nanostructured Metal Chalcogenide Networks As Carbon- and Binder-Free Cathode Materials for Li, Na, and Al-Ion Batteries
Authors: Hawkins Casey , Whittaker-Brooks Luisa
Published: February 2020

2D layered metal chalcogenides have displayed extraordinary properties that have put them on the forefront of various applications as promising catalysts, sensors, electrochromic devices, and electric actuators. Specifically, metal chalcogenides such as titanium (IV) sulfide (TiS2), has been identified as a promising low cost cathode for rechargeable batteries. TiS2 can exhibit specific capacities with a completely lithium-intercalated LixTiS2 (x = 1) as high as 238 mAhg-1. The electrochemical performance of bulk TiS2 cathodes has been hindered by its low ion diffusion coefficient and moderate electrical conductivity. To overcome these challenges, bulk TiS2 cathodes are mixed with conductive additives (typically carbon) and polymer binders (typically polyvinylidene fluoride -PVDF) to yield a paste that is finally cast onto a current collector. However, the electrochemical performance of the electrode is lowered due to the extra weight of all the inactive components (i.e., additives, polymer binder, and metal substrates) introduced during the fabrication. An alternative to the use of pasted electrodes is the direct growth of well-defined nanostructures on a conducting substrate. In this work, we report the synthesis, characterization, and electrochemical performance of carbon- and binder-free cathodes comprised of highly conducting TiS2 nanobelts. The short ion diffusion paths, high electrical conductivity and absence of materials that hinder ion migration such as carbon and PVDF have led to Li-ion and Na-ion batteries exhibiting high capacity, less capacity fade, and resilience under higher cycling rates. Moreover, key to developing new secondary battery systems is multielectron reactions involving more than one electron transfer, which may lead to higher specific capacity and energy density. Herein, we will discuss our recent findings towards rechargeable aluminum batteries comprising carbon- and binder-free TiS2 cathode electrodes. Finally, we will also discuss preliminary results that demonstrate high electrochemical performance of carbon- and binder-free TiS2 electrodes in all-solid state ion batteries.
Spray Coated Nanorod Structured Molybdenum Oxide (MoO3) on Celgard for Ultra-Fast and Highly Stable Next Generation Lithium-Sulfur Battery
Authors: Kaisar Nahid , Abbas Syed Ali , Diang Jiang , Jou Shyankay , Chu Chih-Wei
Published: February 2020

Lithium-sulfur (Li-S) battery with high theoretical energy density of 2600 Wh/kg, expected to be next generation battery. In reality Li-dendrite growth, polysulfide formation, shuttling effect, low conductivity of sulfur and low active material loading become major challenges to develop Li-S battery technology. To overcome these problems we have tried a bilayer separator, which consists of low dimensional molybdenum oxide (MoO3) nanorods on one side and polymer on other side to prevent the migration of polysulfides. The low dimensional transition metal oxide was prepared by simple physical grinding process. 10 wt% solution was prepared in isopropyl alcohol (IPA) and spray coated onto one side of the celgard. Initial capacity of 1185 mAh/g was achieved at 0.5 C (1C=1675mAh/g) and at the end of 500 cycles 80% initial discharge capacity was retained with degradation rate of 0.04% per cycle. Rate capability of the Li-S battery using MoO3 coated separator was measured starting with 0.5 C rate followed by 1 C, 2 C, 3 C, 4 C and finally, return to 0.5 C and the test illustrates that the Li-S battery possesses very good rate capability by showing 93.21% retention of initial discharge capacity.

Figure 1
A New Approach to Synthesis Micrometer-Sized Porous Silicon Anode for Lithium Ion Batteries
Authors: Jia Haiping , Li Xiaolin , Zhang Ji-Guang
Published: February 2020

A New Approach to Synthesis Micrometer-sized Porous Silicon Anode for Lithium Ion batteries

Haiping Jia, Xiaolin Li, and Ji-Guang Zhang

Pacific Northwest National Laboratory, Richland, WA, United States.

With the increasing demand on high energy Li-ion batteries (LIBs) for electric vehicles and other large scale energy storage applications, silicon (Si) based composite material has been regarded as one of the most promising candidate to replace the state-of-the-art graphite anodes and can further boost the specific energy of LIBs to be more than 300 Wh/kg. Silicon has the highest practical capacity of 3,579 mAh g-1 and a relatively low lithiation potential of 0.2 V vs. Li/Li+. However, fast capacity fade still largely limits the practical application of Si based anode. A large volume change during lithiation and delithiation processes lead to pulverization and subsequent loss of electrical contact, continuous consumption of electrolyte, repeated breaking/formation of the solid electrolyte interphase (SEI) and an increase in the overall resistance. There has been significant effort to understand and mitigate the capacity fade in Si-based anodes exploiting nanostructured electrodes, surface coatings, additives and novel binders. These advances have paved the way for practical application of Si-based anodes for Li-ion battery applications. Although significant progress has been made, most nanostructured Si materials have to be prepared by high-cost processes (such as chemical vapor deposition) that are difficult to scale up. Therefore, there is an increasing need to prepare Si microparticles (SiMP) with high conductivity and stable structures.

In this work, we developed a low-cost and scalable synthesis processes to make desired micronmeter scale SiO2/MWNT spheres. The highly spherical SiO2/MWNT macrobeads ranging from 500 nm to 10 µm in diameter were employed as template and silicon precursor (Figure 1a, b). The as-prepared material basically retains the original morphology of template and demonstrates unique hierarchical structure (Figure 1c, d). The fine primary silicon particles can shorten the Li+ transport route, and avoid the pulverization of SiMP. The obtained silicon composite delivers a reversible capacity of 1290 mAh g-1 at 1C and 87% capacity can be retained after 300 cycles. We attribute this promising cycling stability to the well-designed hierarchical structure, which provides: 1) enough void space to accommodate the volume change so that the swelling of the composite can be minimized; 2) good mechanical structure and electronic conductivity from the MWNT matrix. More details on the synthesis process and electrochemical performance of SiMP will be reported in this report.

Figure 1. (a, b) SEM images of microsphere SiO2/MWNT; (c, d) SEM images of the obtained Si/MWNT.

Figure 1
Synthetic Control and Structural Stabilization of Ni-Rich Layered Oxides As High-Energy Cathode Materials for Lithium Ion Batteries
Authors: Zhao Jianqing , Zhu Wenchang , Gao Lijun
Published: February 2020

Ni-rich layered oxides (LiNi1-xMxO2, M=Co, Mn, Al, etc., x<0.5) have been demonstrated as practical cathode materials for high-energy and high-power lithium ion batteries. However, various synthetic factors affect the layered structural ordering of LiNi1-xMxO2 and related electrochemical lithium storage performances. Herein, we report on developing a high-capacity Ni-rich LiNi0.8Co0.1Mn0.1O2 oxide with enhanced cycleability via the synthetic control. Systemic investigation is made to the phase evolution of LiNi0.8Co0.1Mn0.1O2 oxide under different annealing temperatures by ex-situ and in-situ synchrotron X-ray diffraction (XRD) measurements, coupled with quantitative structural analysis through refinements. Structural characterization indicates an intriguing phase transition of LiNi0.8Co0.1Mn0.1O2 from a rock-salt structure at low annealing temperatures directly to a layered α-NaFeO2-type structure with a R-3m space group at high temperatures. The in-situ XRD studies gain us access to the phase diagram in the confined Ni-rich region of the Ni-Mn-Co space, thereby enabling the design of synthetic protocols for preparing high-capacity LiNi1-x-yMnxCoyO2 oxides with stabilized structure and reasonable cycling stability. Furthermore, a preheating process and Li2TiO3 coating layer have been introduced during the synthesis of LiNi0.8Co0.1Mn0.1O2 oxide, in order to manipulate the lithium source reaction by fabricating the outer shell in advance. As a result, the resulting LiNi0.8Co0.1Mn0.1O2 cathode material reveals the higher degree of structural ordering and considerably enhanced lithium storage performances. This work offers a feasible route to optimize the layered structure of Ni-rich cathode materials via the synthetic control of the lithium source reaction, and further sheds light on the fundamental relationship between crystal structure and electrochemical performance for high-energy lithium ion batteries.
Effects of Non-Uniform Temperature Distribution on Degradation of Lithium-Ion Cells
Authors: Zhang Guangsheng
Published: February 2020

Lithium-ion cells degrade much faster at temperatures higher than 25 °C mainly due to accelerated solid-electrolyte interface (SEI) growth in anode and degeneration of cathode [1, 2]. It is also known that temperature distributions in lithium-ion cells are not uniform [3] due to very low thermal conductivity of battery materials. The non-uniform temperature distributions could cause non-uniform degradation, thus exacerbating the thermal degradation problem, especially for large-format lithium-ion cells during high power operation. The effects of non-uniform temperature distributions on degradation of lithium-ion cells will be investigated and progress will be presented.

References

[1] C.Y. Wang, G. Zhang, S. Ge, T. Xu, Y. Ji, X.G. Yang, Y. Leng. Lithium-ion battery structure that self-heats at low temperatures, Nature, 529(7587) (2016) 515-518.

[2] T. Waldmann, M. Wilka, M. Kasper, M. Fleischhammer, M. Wohlfahrt-Mehrens. Temperature dependent ageing mechanisms in lithium-ion batteries – A post-mortem study, Journal of Power Sources, 262 (2014) 129-135.

[3] G. Zhang, L. Cao, S. Ge, C.Y. Wang, C.E. Shaffer, C.D. Rahn. In situ measurement of radial temperature distributions in cylindrical Li-ion cells, Journal of The Electrochemical Society, 161(10) (2014) A1499-A1507.
Modeling Cascading Failure of Thermal Runaway in Stacks of Li-Ion Pouch Cells with Variation in Cooling Attributes
Authors: Shurtz Randy C. , Hewson John
Published: February 2020

The propagation of a local thermal runaway event to adjacent cells will determine the severity of potential local thermal abuse events in large battery packs relevant to transportation or grid-scale storage. Propagation can occur or heat can be dissipated depending on the ratio of the thermochemical reaction rates to the heat transfer rates. Also of importance is the thermal capacity of a system relative to the thermal energy released. We demonstrate these phenomena with recently developed thermochemical models for thermal abuse scenarios. These models have been developed with greater fidelity for high temperature heat release rates that we will show are important. Predictions are compared with recent experiments where thermal runaway was initiated through thermal abuse of one cell and subsequent cascading propagation, or failure to propagate, through the remaining cells in a pack, depending on the energy stored and the thermal characteristics of the battery pack. Implications for cascading failure in larger systems are discussed.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

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