bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Properties of Mo Doped High Voltage Cathode for Lithium-Ion Battery
Authors: Kazda Tomáš , Vondrák Jiří , Vanýsek Petr , Sedlaříková Marie , Tichý Jiří , Čudek Pavel 
Published: February 2020

Lithium-ion batteries play an important role in portable electronic devices and e-mobility due to their high gravimetric energy density. However they are not able to meet the growing demand for higher capacity batteries for extended range electric vehicles.
Alternatively, lithium-sulfur batteries based on multi-step redox conversion reaction provide a theoretical specific capacity of 1675 mAh/g. However LiS batteries also suffer from many problems, such as severe volumetric expansion/contraction during lithiation/de-lithiation, polysulfide (PS) dissolution and shuttling dendritic lithium growth on the anode, corrosion of aluminum current collector, low sulfur utilization and low current efficiency (CE).
In this manuscript, we demonstrate that specific types of sulfur allotropes react differently from standard orthorhombic sulfur used in state of art LiS batteries. Significant improvements are achieved by using sulfur allotropes as both cathode active mass and 3D structural additive. Dissolution of polysulfides is confined within the cathode by the use of a bi-functional additive capable of controlling cathode reaction and the first discharge plateau is extended to deliver a capacity of 408 mAh/g at 0.2C which is close to theoretical limit of 418 mAh/g for long chain PS (Fig.1). Instead of using various methods for controlling PS dissolution and migration which are mostly based on PS binding and interaction with host-catalyst structures, we used a bi-functional additive capable to control both reaction proceeding as well as its kinetics. This method allows PS dissolution but reactions are strictly limited into cathode compartment and cannot proceed outside the cathode. An important aspect of this approach is significantly reduced side-reaction between PS and electrolyte.

Fig.1: Comparison of discharge curves of standard electrode and electrode with bi-functional additive 0.7M LiTFSI + 0.25M LiNO3
, DOL/DME 2:1 v/v, active mass S loading bi-additive 1.95 mg/cm2, standard 1.65 mg/cm2

This research has been carried by Graphene Batteries AS in close cooperation with the Centre for Research and Utilization of Renewable Energy (CVVOZE) as a part of collaboration project NPU I programme (project No. LO1210), (project No. FEKT-S-14-2293)

Figure 1
Improving Metal Anode Stability in Potassium Oxygen Batteries with Concentrated Electrolyte
Authors: Ren Xiaodi , Lau Kah Chun , Wu Yiying 
Published: February 2020

In recent years, metal-oxygen batteries, especially non-aqueous lithium-oxygen batteries (or Li-O2 batteries), have drawn considerable research attention for future energy storage applications due to high theoretical specific energy densities. Compared to conventional lithium-oxygen batteries, potassium-oxygen (K-O2) batteries are based on a reversible O2/KO2 redox chemistry, resulting in much better round-trip efficiencies (higher than 90%) without using electrocatalysts. While the reversibility of the cathode reactions is improved, the cycling performance of K-O2 batteries is greatly limited by the K metal anode stability. The highly reducing K anode would react with electrolyte molecules and degrade seriously during cycling. Moreover, the oxygen crossover to the anode further accelerate the degradation process. Here, we report our studies about the improved K metal anode stability in K-O2 batteries with concentrated electrolytes. It is shown that in this class of electrolytes, a stable Solid Electrolyte Interface (SEI) layer is critical for protecting the K anode and suppressing the undesired side reactions. As a result, the metal anode cycling efficiency and the cycle life of K-O2 batteries can be largely increased.
Materials Selection and Chemistry Development for Redox Flow Batteries
Authors: Wang Wei , Wei Xiaoliang , Li Bin , Vijayakumar Murugesan , Nie Zimin , Sprenkle Vincent 
Published: February 2020

Redox flow battery technologies are leading candidates for stationary energy storage, which provide a potentially cost-effective approach that would be beneficial for renewable energy integration, balancing the mismatch between supply and demand, as well as improving the overall reliability and efficiency of the grid. Until very recently, most research in this area has focused on aqueous electrolyte systems, with the choice of electroactive materials mostly focused on transition-metal redox species, such as the all-vanadium and Fe/Cr redox flow batteries. This choice limits aqueous systems to low energy density because of the low solubility of metal salts in water. Some of the high-cost transition-metal elements further limit the potential of cost reduction of the flow battery system.
Materials selection and chemistry development are therefore of critical important to expand the chemical space for the flow battery technology. Through a molecular ligand design approach, we demonstrate that the structure of organic and inorganic redox active species can be tuned to capture the most attractive properties, such as favorable potential, high solubility, and low cost, etc. In the Zn-I redox chemistry, alcohol (ethanol(EtOH)) can be used as a stabilizing agent to mitigate the triiodide dissociation and subsequent precipitation reaction through direct coordination of EtOH with the zinc cation (Figure 1).1 A new total organic aqueous redox flow battery (OARFB) has also been developed using low-cost and sustainable methyl viologen (MV, anolyte) and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-HO-TEMPO, catholyte), and benign NaCl supporting electrolyte (Figure 2).2The electrochemical properties of the redox active materials and their performance in flow cell will be presented.

Figure 1 a. Triiodide complexed zinc cation and b EtOH-complexed zinc cation formed in the catholyte during the charging process. c. Efficiencies of the cell with (2.5 M ZnI2 + 10 vol% EtOH) and Nafion 115 as membranes tested under the current density of 10 mA cm-2at different temperatures.

Figure 2. Cyclic voltammograms of MV (blue trace) and 4-HO-TEMPO (red trace); conditions: 4.0 mM analyte in 0.5 M NaCl electrolyte; scan rate: 50 mV/s; glassy carbon working electrode; glassy carbon counter electrode; Ag/AgCl reference electrode.

Acknowledgements

The authors would like to acknowledge financial support from the U.S. Department of Energy’s (DOE’s) Office of Electricity Delivery and Energy Reliability (OE) (under Contract No. 57558). Pacific Northwest National Laboratory is a multi-program national laboratory operated by Battelle for DOE under Contract DE-AC05-76RL01830.

References

(1) Li, B.; Nie, Z.; Vijayakumar, M.; Li, G.; Liu, J.; Sprenkle, V.; Wang, W. Nat Commun
2015, 6, 6303.
(2) Liu, T.; Wei, X.; Nie, Z.; Sprenkle, V.; Wang, W. Advanced Energy Materials
2015, n/a.

Figure 1
Multi-Directional 3D Laser Scanning of Lithium-Ion Cells to Detect Inhomogeneity during Cycling and Aging
Authors: Rieger Bernhard , Erhard Simon Vincent , Keil Peter , Jossen Andreas 
Published: February 2020

Introduction

Measuring the thickness of lithium-ion batteries is a reliable method to detect the intercalation stages of the electrodes, the state of charge and irreversible effects during aging [1]. When using tactile high-precision displacement sensors, the measurement is limited to only a few positions of the cell at the same time [2].

Experimental

In this work, we developed a test stand, which enables simultaneous precise thickness measurement at 100 positions of the cell. This allows for investigations of the homogeneity of mechanical expansion during charging and discharging, as well as non-destructive state-of-health (SOH) mapping. In a first step, inhomogeneity of mechanical expansion during cycling is studied. In a second step, the effects of expansion inhomogeneity during cycling on the aging behavior of the cells are investigated by determining the irreversible and reversible thickness change at each of the 100 positions every 100th cycle.

Results

We found that the cell contracts homogeneously during discharge, whereas a significant overshoot in the thickness increase during high-rate charging at the current collector tabs is observed at 25 °C. When the ambient temperature is increased to 40 °C, this inhomogeneity is no longer observable. This effect has been ascribed in literature to non-homogeneous intercalation of Li-ions due to the interplay of fast and slow Li ion diffusion processes [3]. The SOH distributions reveal a homogeneous aging of the cells cycled at low charging rate and high charging rate at 40 °C. Compared to that, the cells cycled at high charging rate at 25 °C show inhomogeneous degradation in areas close to the current collector tabs which show the largest degradation.

Literature

[1] J. Cannarella, C.B. Arnold, Journal of Power Sources 269 (2014) 7–14.
[2] K.-Y. Oh, J.B. Siegel, L. Secondo, S.U. Kim, N.A. Samad, J. Qin, D. Anderson, K. Garikipati, A. Knobloch, B.I. Epureanu, C.W. Monroe, A. Stefanopoulou, Journal of Power Sources (2014).
[3] L.W. Sommer, P. Kiesel, A. Ganguli, A. Lochbaum, B. Saha, J. Schwartz, C.-J. Bae, M. Alamgir, A. Raghavan, Journal of Power Sources 296 (2015) 46–52.

Figure 1
Development of an Li2FeSiO4 Vs. Graphite Lib for Sustainable Energy Storage
Authors: Thomas Josh , Cai Jingjing , Eriksson Henrik , Fredin Kristofer , Liivat Anti , Gustafsson Torbjörn , Skårman Björn , Vidarsson Hilmar 
Published: February 2020

The development of larger, more efficient, cheaper, safer and necessarily “greener” Li-ion batteries (LIBs) for electric vehicle (EV) and especially stationary energy-storage applications continues to present a major challenge to battery researchers and developers the World over. There are several underlying reasons for this; not least, the availability and cost of appropriate raw materials. For example, several millions of tons/year of active cathode material will be needed if we are to achieve the long-term goal of a worldwide transition from ICEs to EVs – and to realistically cheap LIBs for use in large-scale sustainable-energy storage applications.
In this context, the absence of an ideal CATHODE material with a sufficiently high energy-density is arguably the most serious bottleneck facing us. A significant breakthrough has come with the development of polyanion-based cathode materials; typically, phosphates and silicates: e.g., LiFePO4 [1] and Li2FeSiO4 [2]. These materials are expected to be both cheaper and safer than conventional LIB transition-metal oxide cathode materials. A negative feature of these materials is, however, their poor electronic conductivity – a problem which is normally addressed by reducing particle-size into the nano-range and promoting ion conductivity through the use of various particle-surface coatings. Arguably the most promising cathode materials for large-scale applications involve the Li-M-SiO4 family of silicates, typically Li2FeSiO4.
We present here an account of our recent advances in addressing the challenge of scaling up our successes on a lab-scale to produce well-functioning Li2FeSiO4 vs. graphite full-cell prototypes suitable for the sustainable energy storage market.

Keywords: lithium-ion battery, cathode material, scale-up, EV, sustainable-energy storage

REFERENCES

[1] A.K. Padhi et al., J. Electrochem. Soc., 144, 1609 (1997).
[2] A. Nytén et al., Electrochem. Commun., 7, 156 (2005).

ACKNOWLEDGEMENTS

This work has been supported by the Global Climate and Energy Project of Stanford (GCEP), the
Swedish Energy Agency (STEM), VINNOVA and the Swedish Science Research Council (VR).
How Mixing Tetraglyme with Ionic Liquid Changes Volumetric and Transport Properties: An Experimental and Computational Study
Authors: Zhang Yong , Maginn Edward J. 
Published: February 2020

Ionic liquids (ILs) are salts possessing many properties that make them attractive for use in a wide range of applications including batteries. One of the biggest drawbacks of ILs is that they tend to be more viscous than conventional solvents, which means low ionic conductivity when used as electrolytes in batteries. One effective way to lower the viscosities is to mix ILs with low viscosity additives such as molecular solvents. An obvious disadvantage of mixing molecular solvents with ILs is that the extremely low volatility of the IL is compromised by the finite vapor pressure of the diluent. One strategy to overcome this is to mix ILs with molecular solvents that are themselves of very low volatility. One such class of compounds are the glymes, which are oligoethers having a CH3O-(CH2CH2O)n-CH3 structure. In addition to having low volatility, glymes are effective at dissociating salts because of the electron donating nature of their ether oxygen groups. They also tend to have high thermal and electrochemical stability, which has led many groups to investigate mixing glymes with alkali metal salts (most commonly Li+ [NTf2]) for use as electrolytes in batteries. The alkali metal cation tends to coordinate with the oxygen atoms of the glyme, which can significantly lower the melting point of the salt. Such systems usually retain the attractive properties of pure ILs but the transport properties are improved. They are considered a new class of ILs and have been termed “solvate ILs”. Tetraethylene glycol dimethyl ether (tetraglyme or G4) is a particularly promising glyme.
While there are many studies devoted to the properties of Li-based solvate ILs, much less work has been done investigating the properties of mixtures containing glymes and more conventional ionic liquids. In the current work, the density and viscosity of the IL [C6mim][NTf2]) and its mixtures with tetraglyme were measured at different temperatures and concentrations. Molecular dynamics (MD) simulations were also carried out on the mixtures in order to compute the density, self-diffusivity, viscosity, ideal ionic conductivity and liquid structure. We find that both the density and viscosity drop with increasing temperature and G4 concentration. Detailed analysis of the simulation results suggests that G4 preferentially solvates the cations, thereby weakening the interactions with the anions and resulting in faster dynamics, particularly for the anions. Such behavior was previously observed in solvate ionic liquids. Based on the simulation results of a model G4 system, it was further revealed that the localized negative charges on the oxygen atoms of G4 are primarily responsible for the preferential solvation of cations. If G4 (or a similar solvent) instead had large localized positive charges, it would tend to preferentially solvate the anions, resulting in increased cation mobility. This suggests a strategy for selecting molecular solvents that will selectively enhance cation dynamics.
Modelling of Li+ and Na+ Conduction Under Electric Fields in Organic Ionic Plastic Crystals
Authors: Jónsson Erlendur , Chen Fangfang , Forsyth Maria 
Published: February 2020

Solid electrolytes are a promising topic, which could replace the flammable solvents currently used for both Li-ion battery electrolytes, and their Na-counterpart (still under development). Thus the transport properties of such solid electrolytes must be understood. Here, we studied the effect of applying an external electric field to an organic ionic plastic crystal, P1224PF6, previously reported to have interesting alkali-ion transport properties[i]. The study employed molecular dynamics (using a previously reported force field[ii]).
The roles of electric field strength and Li+/Na+ concentration were explored. Furthermore, system polarisation was explored by adding a surface/electrode to the system. This was done both on the basis of an external electric field and one due to electrode charge.

[i] Chen, F., Pringle, J.M., Forsyth, M. Chem. Mater.
2015, 27, 2666-2672.
[ii] Chen, F., Jin, L., de Leeuw, S.W., Pringle, J.M., Forsyth, M. J. Chem. Phys.
2013, 138, 244503.
Electrode Degradation Analysis in Li-Ion Batteries
Authors: Malik Romeo , Finegan Donal P , Huang Qianye , Loveridge Melanie , Shearing Paul R. , Bhagat Rohit 
Published: February 2020

This study investigates modes of degradation in composite silicon (Si) anodes for Li-ion batteries, with emphasis on the electrode architecture. In recent years, considerable studies have shown that crystalline Si is a promising negative electrode candidate, with a specific capacity of 3579 mAh/g which is ca. 10 times the specific capacity of graphite. However, Si still has major performance issues associated with it, predominantly the volume expansion (up to 280%) which can result in cracking and pulverisation of active particles. Additionally the surface of the Si reacts with the electrolyte at lower voltages to form the solid-electrolyte interphase (SEI) – a major source of continued irreversible Li loss. Subsequent charge-discharge cycling causes repeated disruption of the SEI layer where it continues to form and grow. These phenomena culminate in conductivity loss and capacity fade. Despite the numerous studies and evolution of sophisticated in-situ characterisation techniques, relatively little is understood still about the microstructural evolution and its impact and relation to the cell performance during operation and failure. Therefore, a more detailed study is required to fully characterise types of crystalline Si as well as the importance of electrode architectures for high capacity lithium-ion storage materials.
It is imperative to comprehensively understand the fundamental degradation mechanisms inside anode microstructures and at their interfaces. X-ray computed tomography (CT), in conjunction with impedance spectroscopy and associated physical characterization, will be employed to capture and quantify key aspects of the evolution of internal morphology and resistance build up. This includes characterisation of SEI growth, porosity changes and conductive network breakdown during charge-discharge operation. The study will also include in-situ and operando tomography, and diffraction experiments for clearer insights into key degradation processes, such as delamination, initiation and propagation of particle cracking as well as time-resolved identification of phase transformations. X-ray CT has been proven to be an effective tool to explore the hierarchical structure of battery electrodes and for diagnosing battery failure mechanisms at multiple- length scales. This approach will enable us to observe and quantify failures in Li-ion batteries at the electrode level, and thus facilitate construction of better electrode architectures.
This study aims to characterise electrode structures to be able to develop and compare microstructural architecture with performance. It is anticipated that this study will influence major improvements in the design of Li-ion battery materials and their processing which in turn positively impact cell performance.

Figure 1
Investigation of Reaction Kinetics in Oxide Nanostructures for Li Ion Battery Conversion Electrodes
Authors: Kim Jae Jin , Fister Timothy T , Emery Jonathan D , Suh Hyo Seon , Elam Jeffrey W , Martinson Alex B. F. , Nealey Paul F. , Fenter Paul 
Published: February 2020

As one of promising candidates for achieving a higher capacity Li ion battery electrode, transition metal oxides can electrochemically react with lithium to form lithium oxide and reduced metal phases as a so-called conversion reaction. Despite its higher energy density and use of cheaper materials than conventional intercalation materials, conversion materials have been commercially limited by several factors, including its slow, diffusion-limited kinetics, poor cycling performance driven by substantial structural re-organization and corresponding large volume changes, and Coulombic inefficiency—especially in the first cycle. In addition, there are substantial deviations in redox potentials for conversion reactions in oxides with respect to the thermodynamically expected values (Etherm~ 2 V). It is obvious that the interfacial processes play a critical role in the overall conversion reaction which enlists charge/mass transport through a complex network of metal-rich and lithia-rich domains and consequent nucleation/growth.
To understand and control the reaction kinetics, we have studied nanoscale model electrodes that take advantage of a geometrically well-defined, simple and reproducible structure, which enables us to investigate more readily the correlation between electrochemical reactivity and electrode microstructure. Using epitaxial thin films, we explore the role of strain and initial metal oxide surface structure on the potential for lithiation. To control transport and phase-separation, we have also examined various nanoscale oxide structures including spheres, cylinders and lamellae structures. These electrodes are prepared by combining the rich phase-space of self-assembled block copolymers with sequential infiltration synthesis via atomic layer deposition. Traditional scanning probe methods are combined with both in situ x-ray diffraction and small angle scattering to investigate the controlled phase separation of a conversion reaction. These results provide deeper knowledge of the reaction kinetics and new perspective on the energy loss mechanisms in conversion reaction while helping develop strategies for improving the viability of conversion materials.