bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic Perspective on Co-Intercalation Behavior of Li/Mg Dual Cations in Intercalation Cathode Materials
Authors: Li Hongyi , Hatakeyama Takuya , Okamoto Norihiko L. , Kumagai Yu , Oba Fumiyasu , Ichitsubo Tetsu
Published: February 2020

Post Li-ion batteries using multivalent ions, such as Mg2+, Ca2+, Zn2+, have attracted much attention in recent years, but developing appropriate intercalation cathode materials for these multivalent cations remains a difficult task due to the sluggish solid-phase diffusion behavior, which is usually caused by the strong coulomb interaction between multivalent cations with the ionic cathode hosts. As an attempt to solve this problem, we proposed a new battery technology, which is referred to as Li-Mg dual-cation batteries.[1-2] The Li-Mg dual-cation batteries possess a so-called “rocking-chair”-type structure, where Li ion and Mg ion are involved in each half-cell reaction simultaneously.

When exploring the characteristics of these batteries, we found an interesting phenomenon that Mg intercalation usually shows higher discharge potential in Li-Mg dual-cation electrolyte than in Mg single-cation electrolyte. The increase of discharge potential (i.e. decrease of the overpotential for Mg intercalation) strongly suggests that the co-existing Li ion is helpful to promote the Mg intercalation with cathode hosts. To elucidate what causes this phenomenon, we performed the first-principles calculations[3-4] with the Nudged Elastic Band (NEB) method[5] to estimate the activation energy of Mg cation migration in cathode hosts that are discharged in Li or Mg single-cation and Li-Mg dual-cation electrolytes and finally revealed a facilitating mechanism for the solid-phase diffusion of Mg cation.[6]

In this presentation, we give a comprehensive explanation on the co-intercalation behavior of Li ion and Mg ion in Li-Mg dual-cation batteries, especially from a thermodynamic perspective. This work advances the fundamental understanding of ionic conduction phenomena of multivalent cations, which is indispensable for developing future energy storage devices.

[1] T. Ichitsubo, S. Okamoto, T. Kawaguchi, Y, Kumagai, F. Oba, S. Yagi, N. Goto, T, Doi, E. Matsubara, J. Mater. Chem. A
3, 10188(2015).

[2] H. Li, T. Ichitsubo, S. Yagi, E. Matsubara, J. Mater. Chem. A
5, 3534(2017).

[3] P. E. Blöchl, Phys. Rev. B
50, 17953(1994).

[4] J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett.
77, 3865(1996).

[5] G. Henkelman, B. P. Uberuaga, H. Jónsson, J. Chem. Phys.
113, 9901(2000).

[6] H. Li, N. L. Okamoto, T. Hatakeyama, Y, Kumagai, F. Oba, T. Ichitsubo, Adv. Energy Mater.
8, 1801475(2018).
Experimental and Theoretical Investigation of Lithium Sulfide Deposition on a Polished Graphite Cathode for Lithium-Sulfur Batteries during Discharge
Authors: Shen Chao , Andrei Petru , Zheng Jim P.
Published: February 2020

Solid deposition accounts for three quarters of the theoretical capacity in lithium-sulfur (Li-S) batteries with liquid electrolyte. Despite extensive research efforts on cathode material synthesis, little knowledge has been gained so far in understanding and controlling the growth of solid discharge product in Li-S batteries. In this work, a polished graphite was used as the standard cathode material to understand the growth mechanism of Li2S.1 To avoid the effects of higher-order lithium polysulfides,2,3 the battery was discharged by starting with a fresh liquid Li2S4 catholyte. The SEM analysis of the discharged cathodes indicates that the Li2S precipitate can grow over a micrometer in size and its morphology strongly depends on the depth of discharge (DODs) and discharge rate of the cell. In addition, the morphology evolution and the in-situ electrochemical impedance spectra (EIS) show that the Li2S follows a dissolution-precipitation mechanism during its deposition on the graphite surface. Finally, a mathematical model based on the multicomponent transport theory4 is developed and used to describe the nucleation and precipitation phenomena on the 2D surface and the EIS spectra at different DODs. The model confirms that the surface passivation of the cathode plays a major role during the discharge of the battery and offers a simple way to measure experimentally the surface coverage as a function of the DOD in Li-S batteries.

C. Shen, P. Andrei, and J. P. Zheng, ACS Appl. Energy Mater, accepted.

C. Shen, J. Xie, M. Zhang, P. Andrei, M. Hendrickson, E. J. Plichta, and J. P. Zheng, Electrochim. Acta, 248, 90–97 (2017).

C. Shen, J. Xie, M. Zhang, J. P. Zheng, M. Hendrickson, and E. J. Plichta, J. Electrochem. Soc., 164, A1220–A1222 (2017).

P. Andrei, C. Shen, and J. P. Zheng, Electrochim. Acta, 284, 469–484 (2018).
Li-Substituted Layered-Spinel Cathode Material for Sodium-Ion Batteries
Authors: Deng Changjian , Skinner Paige , Liu Yuzi , Hunt Riley , Lau Miu Lun , Sun Meiling , Ma Chunrong , Tong Wei , Xu Jing , Xiong Hui (Claire)
Published: February 2020

Sodium-ion battery (SIB) has been considered as an attractive technology for the next-generation, large-scale energy storage systems (EES) in support of reliable, robust and cost-effective electrical power grids.1-4 The O3-type layered Na(NixFeyMnz)O2 (0 < x, y, z< 1) cathode materials are of great interest in sodium-ion batteries due to the abundance and cost of raw materials and their high specific capacities. However, the cycling stability and rate capability at high voltages (>4.0V) of these materials remains an issue. Herein, we successfully synthesized a Li-substituted layered-tunneled (O3-spinel) intergrowth cathode (LS-NFM) to address these issues. The remarkable structural compatibility and connectivity of the two phases were confirmed by X-ray diffraction (XRD), selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). LS-NFM electrode reached a discharge capacity 107 mAh g-1 with a capacity retention of 95% after 50 cycles at a current rate of 100 mA g-1 in a voltage window of 2.0 - 4.2 V. Moreover, the LS-NFM cathode exhibited an enhanced rate capability in comparison to the un-doped layered cathode (NFM). The enhanced rate capability of LS-NFM can be explained by the significantly increased effective Na+ diffusivity measured by galvanostatic intermittent titration technique (GITT) compared to the un-doped control NFM cathode, which can be ascribed to the improved charge transport kinetics through shortened diffusion path by direct connection between the 3D channels in the spinel phase and 2D channels in the layered phase. The results from ex situ hard/soft X-ray adsorption spectroscopy (XAS) suggest that the capacity of LS-NFM cathode is mainly associated with the Ni2+/Ni4+ redox couple, and slightly from the Fe3+/Fe4+ redox couple. The voltage profile of the LS-NFM cathode exhibited a reversible plateau above 4.0 V, indicating great stability at high voltages and structural stabilization by the spinel phase. In addition to the substitution of various transition metals, or the modification of the stoichiometry of each transition metal, this study provides a new strategy to improve electrochemical performance of layered cathode materials for sodium ion batteries.

References:

(1) Yabuuchi, N.; Kubota, K.; Dahbi, M.; Komaba, S. Chemical Reviews
2014, 114, 11636.

(2) Pan, H. L.; Hu, Y. S.; Chen, L. Q. Energ Environ Sci
2013, 6, 2338.

(3) Kundu, D.; Talaie, E.; Duffort, V.; Nazar, L. F. Angew Chem Int Edit
2015, 54, 3431.

(4) Slater, M. D.; Kim, D.; Lee, E.; Johnson, C. S. Advanced Functional Materials
2013, 23, 947.

Figure 1
Sodiation Driven Mechano-Electrochemical Interaction in Alloy Electrodes
Authors: Sarkar Susmita , Verma Ankit , Mukherjee Partha P.
Published: February 2020

The abundance of alkaline sodium (Na) is promising toward achieving a better, cheaper and more efficient energy storage system for renewable energy integration into the electric grid. However, the intercalation-based anode materials of Na-ion battery are inadequate in storing bulky Na ions which raises the concern about efficient reversibility. Desirable alternatives are alloy-based anode material such as tin (Sn), which has relatively high theoretical capacity of 847 mAh/g (for complete conversion of Na15Sn4). However, rapid volume expansion, which strains basic Sn skeletons, coupled with more frequent and extreme noxious events linked to electrolyte decomposition exacerbates the Na-Sn cycling properties and deteriorate the reversibility. The goal of this study to is to wade through different combinations of binders and electrolytes and extract kinetic and transport properties of Sn based Na-ion chemistry and to elucidate mechano-electrochemical underpinnings thereof.
Ion Tracking in Aqueous Sodium-Ion Batteries
Authors: Oleson Karl , Madden Thomas
Published: February 2020

An energy economy based on renewable technologies will need energy storage capabilities on an enormous scale to combat power generation fluctuations. To provide the amount of energy storage that will be needed, low-cost batteries made with earth abundant elements will be a necessity for grid-scale storage. Furthermore, these batteries should have chemistries that can guarantee safety for the users and be non-toxic to the environment. Aqueous sodium-ion batteries (ASIB) are one option that can fill these requirements while also promising long lifetimes. There has been considerable effort put forth into the development of sodium ion intercalation batteries that combine sodium and lithium chemistries. Sodium titanium phosphate (NTP) as the anode and lithium manganese oxide (LMO) as the cathode are a commonly researched pairing. While the LMO is only capable of cycling the lithium ions in solution, the NTP is capable of cycling both sodium and lithium ions, although to different degrees at different potentials. This talk will look into the conditions at which the different ions cycle into the NTP, how this can turn sodium titanium phosphate into lithium titanium phosphate (LTP), as well as the effect that lithium insertion into NTP has on the LMO cathode. This will be done by tracking ionic concentrations in laboratory scale batteries at different states-of-charge (SOC’s) and states-of-health (SOH) and correlating to differential capacity curves. Comparisons will be made against ex-situ cyclic voltammetry studies for NTP and LTP when these materials are exposed to different ratios of Li+ and Na+ in solution.
Properties of Thin Lithium Metal Electrode in Carbonate Electrolytes
Authors: Guo Juchen , Zhang Jian
Published: February 2020

The utilization of Li anode in Li-ion batteries is still illusive to date: In addition to the significant safety hazard, Li anode suffers from inferior cycle stability. Furthermore, the majority of the lab-scale investigations uses thick Li foils as the study subject, which can behave extremely differently from the practical Li anode. To provide a realistic baseline to evaluate the electrochemical performance of Li anode in liquid electrolytes, the electrochemical and micromorphological properties of thin Li film (50 µm) are investigated in this study. The deposition-stripping coulombic efficiency (CE) of the thin lithium electrode and the cycle life of the symmetric cell under various conditions are measured combined with microscopic and spectroscopic characterizations. The failure mechanism of the symmetric cells is also investigated. Our results indicates the average CE is strongly related to the cycling parameters including area capacity (depth of Li utilization), C rate and cycle number; and indicating loose relationship with the type of Li salts and concentration due to beneficial surface compounds. Meanwhile, CE has no correlation to the cycle lives of the symmetric cells, which is clearly dictated by the areal capacity and C rate. Our results also suggest that the failing of symmetric cells is due to “soft shorting” (direct contact of SEI covered Li) due to the separator breach induced by the drastic volume change of Li electrode during deposition.
Enhancing the Performance of Vanadium Redox Flow Batteries Using Carbon Cloth Electrode Decorated with C/WOx Nanocomposites
Authors: El Diwany Farah , El Sawy Ehab N , Allam Nageh
Published: February 2020

Given the growing world population and the industrial revolution, there is an immense global energy demand, which has heavily been established by fossil fuels for several decades. However, the depletion rate of fossil fuel reserves and their environmental hazards have led the global energy systems to shift to using renewable energy sources. Even though the roles of solar and wind energy are expected to increase over the coming years, their intermittent behavior requires their integration with electrical energy storage systems for frequency balancing and efficient utilization. Whereas conventional energy storage techniques (e.g., pumped hydro, compressed air, flywheel, and thermal energy) have large footprints, require big investments and lack flexibility, electrochemical energy storage methods, have higher energy density and better flexibility depending on their design. Compared to other electrochemical systems (e.g., Li-ion batteries and supercapacitors), vanadium redox flow batteries are thought to be an optimal solution to create smart grids when combined with renewable energy sources, owing to their scalability, site versatility, long lifetime and ease of operation.

Nevertheless, there are some issues concerning their efficiency and further market penetration, including (i) low solubility of vanadium ions in acidic electrolyte leading to low energy density; (ii) crossover of vanadium ions through membrane leading to self-discharge and low capacity; and (iii) slow kinetics of vanadium ions reactions at the electrodes. Even though the widely used carbon-based electrodes have high stability in acidic solutions and high conductivity, modifications are needed to improve the kinetics of the electrocatalytic reaction, which is the aspect being concerned in this study. Thermal treatment of carbon cloth showed faster electrode kinetics at 0.1 M and 1 M vanadium ion concentration in pure H2SO4 and H2SO4/HCl. Incorporation of carbon and tungsten oxide nanostructures also demonstrated excellent electrocatalytic activity, resulting in high energy efficiency. A proposed description of the poorly understood mechanism of this electrochemical reaction will be presented, along with these findings, allowing for a big step forward towards a more efficient vanadium redox flow battery.
(Invited) A Breath of Fresh Air in Solid State Battery: Moving Beyond Sulfide Solid Electrolyte
Authors: Zimmerman Mike , Muldoon John
Published: February 2020

Polymer materials are ubiquitous in current battery technology and are commonly used as binders, separators and packaging. Poly(ethylene oxide) (PEO) was first discovered to dissolve Li salts in 1973, making its use as an electrolyte possible. Today, it is still one of the most intensely studied and widely used polymer electrolytes; however, the conductivity is several orders of magnitude lower than inorganic solid electrolytes. This easy-to-synthesize, polymer electrolyte has the potential to be a superior candidate to present-day inorganic solid electrolytes. We will report the properties of a breakthrough polymer technology with a new Li+ conduction mechanism that does not rely on chain-segmental motion as with PEO. This new polymer electrolyte supports high-Li+-conductivity while maintaining a wide electrochemical window. We will present the performance of this electrolyte with a wide variety of anodes and cathodes.
Novel Electrolytes to Enable Energy Dense Batteries
Authors: Mohtadi Rana , Tutusaus Oscar
Published: February 2020

The ever-increasing demands for safe, energy dense and low cost energy storage systems have been driving interests in beyond Li-ion batteries such as those based on Li metal, magnesium metal and all solid state battery systems[1,2]. These high energy density batteries suffer from several challenges, several of which are related to the instability or incompatibility of the electrolytes[1,3,4]. Our group has been pioneering the development of electrolytes that enabled overcoming several key challenges in magnesium batteries and created a new family of highly performing and practical electrolytes [3,4]. One challenge with electrolytes for batteries in general is the high flammability and volatility, that can be overcome with the use ionic liquid solvents. However, available ionic liquids suffer from several key draw backs associated with insufficient anodic stability and incompatibility with reactive metallic anode.

Herein, we outline the classes of electrolyte materials we developed and how we overcome current challenges with ionic liquids for Mg and Li metal batteries.[5]

References

[1] Choi J. W. Aurbach D. Nature Reviews Materials 1, 2016, 16013 1-16.

[2] Manthiram A., Yu X., Wang S. Nature Reviews Materials 2, 2017 16103.

[3] Mohtadi R., Orimo S., Nature Reviews Materials, 2016, 2,16091. 1311.

[4] Mohtadi R., Mizuno F. Beilstein J. Nanotechnol. 2014, 5, 1291–

[5] Kar, M., Tutusaus O., Doug R. MacFarlane, Mohtadi R., Energy Environ. Sci., 2018, Advance Article
Amorphous Silicon Nitride - an Anode Material for the Next Generation Li-Ion Batteries
Authors: Ulvestad Asbjørn , Koposov Alexey Y , Skare Marte O , Preston Thomas J , Prytz Oystein , Mæhlen Jan Petter , Andersen Hanne Flåten
Published: February 2020

Despite a decade of extensive research, silicon, as material for anodes of lithium ion batteries, still has not become a practical solution. Suffering from enormous expansion/contraction during lithiation/delithiation cycles, silicon undergoes rapid self-destruction resulting in battery failure. To counteract the degradation several options has been explored over the years. Those include downsizing of the material to nanoparticles, doping and coating with organic or inorganic shells.

An alternative approach was proposed to mitigate the structural destruction of silicon, which is preparation of the alloyed materials. In the present work we demonstrate the use of nanostructured amorphous substoichiometric silicon nitride as such alternative anode material. We demonstrate that upon lithiation, silicon nitride forms lithiated subunits of silicon and ternary phase of lithium silicon nitride, which serves as a matrix material. Such phase separation leads to remarkable stability: the nanostructured thin films of SiNx allowed fabrication of electrodes exhibiting capacities above 1500 mAh/g for 2000 cycles. To achieve sufficient capacities for the practical applications, we demonstrate the application of this principle to particle-based composite electrodes, using SiNx nanoparticles fabricated through a CVD process. Such amorphous substoichiometric nanoparticles demonstrated reversible capacities above 1000 mAh/g and excellent cycling stability over several hundred cycles. We also demonstrate the effects of chemical composition on initial and long-term cycling stability of nanostructured silicon nitride.
Single-Step Synthesis of Highly Conductive Na3PS4 Solid Electrolyte for Sodium All Solid State Batteries
Authors: Nguyen Han , Banerjee Abhik , Wang Xuefeng , Wu Erik , Doux Jean-Marie , Meng Ying Shirley
Published: February 2020

Na3PS4 has been demonstrated to be a promising solid electrolyte material to be used in all-solid-state sodium batteries. Although, much research has been conducted on this electrolyte, there is no consensus on the optimal synthesis protocols that form similar material properties from the electrolyte. This work investigates the present synthesis parameters and variations and determines the critical parameters used to synthesize highly conductive Na3PS4. By using only ball milling, a single-step and scalable synthesis method was determined to form Na3PS4 from its starting precursors.
A Systematic Comparative Analysis of Redox Mediators in Li-O2 Batteries
Authors: Kim Hun , Nguyen Trung Thien , Sun Yang-Kook
Published: February 2020

To solve the low-energy efficiency problem of Li-O2 batteries, many kinds of redox mediators (RMs) have been studied. However, systematic research looking into the problems of RMs in these systems are insufficient. We compare herein effects and problems of RMs in Li-O2 batteries by applying unique methodology, based on two types of cells, comparison between argon and oxygen atmospheres and combining electrochemistry in conjunction with spectroscopy. Using systematic electrochemical measurements, representative RMs in Li-O2 battery prototypes were thoroughly explored with respect to oxygen presence, voltage ranges and scan rates. By this comparative, multi-parameters study we reached valuable insights. We identified possible routes for RMs degradation in Li-O2 batteries related to the cathode side, using bi-compartments cells with solid electrolyte that blocks the crossover between the cathode and the Li metal sides. Based on comparative research, we confirmed that degradation of the RMs activity was caused by intrinsic decomposition of the RMs in the electrolyte solution at the cathode part, even before further reactions with reduced oxygen species. This work provides a realistic view of the role of important RMs in Li-O2 batteries and suggests guidelines for selecting suitable RMs, mandatory additive in Li-O2 batteries electrolyte.

References

W.-J. Kwak, H.-G. Jung, D. Aurbach, and Y.-K. Sun, Adv. Energy Mater. 2017, 7, 1701232.

W.-J. Kwak, J.-B. Park, H.-G. Jung, and Y.-K. Sun, ACS Energy Lett.
2017, 2, 12, 2756.

H.-G. Jung, J. Hassoun, J.-B. Park, Y.-K. Sun, and B. Scrosati, Nat. Chem. 2012, 4, 579.
Probing Solid-Solid Interfacial Reactions in All-Solid-State Batteries
Authors: Tang Hanmei , Deng Zhi , Banerjee Abhik , Wu Erik , Nguyen Han , Meng Shirley , Ong Shyue Ping
Published: February 2020

We have developed a hierarchy of DFT-based approaches to understand and design electrode/buffer/SE interfaces in all-solid-state batteries. Even with relatively efficient thermodynamics approximations, we reveal that S-O exchange reactions between oxides (O2-) and thiophosphates (PS4
3-) resulting in the formation of phosphates (PO4
3-) are responsible for large reaction driving force between the common NaMO2 (M = Co, Ni, Fe, Mn) cathodes and Na3PS4 SE. Such reactions, with their associated large volume changes, can be mitigated by careful selection of the cathode/SE combination, or the use of buffer layers with good stability between both materials. We have also identified several promising binary oxides with similar or better chemical compatibility with most electrodes and SEs than the commonly-used Al2O3.

Despite the success of thermodynamics-based approximations, we further demonstrate that explicit modelling of the electrode/SE interface via ab initio molecular dynamics (AIMD) simulations sometimes yield different and more realistic predictions of interfacial reaction products. For example, AIMD predicts that formation of SO4
2– are kinetically favored over the formation of PO4
3– at the NaCoO2/Na3PS4 interface model, in contrast to the predictions of the thermodynamic models. These observations have been validated experimentally. We have also extended such studies to the LiNi0.85Co0.1Al0.05O2/Li6PS5Cl interface, with and without buffer layers, and the predicted interfacial reactions are in good agreement with experimental characterizations.
In Operando XAFS of Vanadium Oxide Nanomaterials Produced through Rapid Microwave Synthesis
Authors: Booth Samuel Guy , Corr Serena
Published: February 2020

The increase in demand for portable electronics combined with a need for grid storage to match the expansion of renewable energy sources has led to a requirement for new, higher capacity electrode materials. For such a development, vanadium is a promising material due to the number of readily accessible oxidation states. The ability to access multiple oxidation states results in much higher theoretical capacities when compared to sites capable of only single electron transfer.1 A number of previously studied materials have shown that such an increase in capacity can come at the cost of battery cyclability. Where the intercalation and deintercalation processes result in the breakdown of the framework structure, causing the rapid capacity fade.

In our lab we have been developing microwave-based reactions to produce a number of different vanadium oxide structures from V2O5. Such structures can be formed using non-harmful solvents with rapid reaction times (on the order of 2-4 hours). Whereas, to produce the same materials, traditional hydrothermal methods often require higher reaction temperatures and need to be run for upwards of a day, making them more energy intensive.

Such structures are of great interest as outlined above, however, to develop them further it is key to understand how the structures may alter during cycling to start to understand the degradation mechanisms. Alongside bulk techniques such as XRD and IR, highly incisive structural information can be garnered through X-ray absorption fine structural (XAFS) analysis; an element specific, local probe. When measurements are conducted during battery cycling, this can give precise information about what is happening to the local structure and how reversible the changes in structure are on charge and discharge.2 Such information provides a clear demonstration of the suitability of the materials for future battery cathodes. Additionally, a broader idea of the likely stresses induced in the structure will aid the design of model architectures for future battery materials.

1 J. Prado-Gonjal, B. Molero-Sánchez, D. Ávila-Brande, E. Morán, J. C. Pérez-Flores, A. Kuhn and F. Garcia-Alvarado, J. Power Sources, 2013, 232, 173-180.

2 Y. N. Zhou, J. Ma, E. Hu, X. Yu, L. Gu, K. Nam, L. Chen, Z. Wang and X. Q. Yang, Nature Commun, 2014, 5, 1-8.
A Series of Polyhydric Esters As Novel Candidates for Battery Solvents in Lithium Metal Cells: Electrochemical Investigations and Influences of Moisture and Alcohol Residues in Contact with Lithium Metal
Authors: Grünebaum Mariano , Buchheit Annika , Lürenbaum Constantin , Winter Martin , Wiemhöfer Hans-Dieter
Published: February 2020

In recent years, the lithium metal anode has aroused great interest, not at least through the development of the lithium//sulfur and the lithium//air battery technologies, in all-solid-state batteries. However, the application of lithium metal anodes is limited by safety issues and several failure mechanisms, including, dendrite growth and direct chemical reactions with electrolyte components like battery solvents, which leads to fast capacity losses.

In this context, a new series of polyhydric propyl-based esters were investigated, namely n-propyl acetate, isopropyl acetate (monohydric esters), trimethylene diacetate, 1,2-propylene glycol diacetate (dihydric esters) and triacetin (trihydric ester) as attractive and environmental friendly candidates for electrolyte solvents in lithium metal battery applications.The above mentioned organic esters were examined in respect to their reactivity in contact with lithium metal, influenced by water or alcohol impurities. The resulting reaction products were analyzed and determined via 1H-NMR spectroscopy. Additional experiments were performed and the resulting products compared to anticipated reaction products which were prepared separately, to evidence possible reaction mechanisms like the occurrence of a CLAISEN-condensation.

Furthermore, the here mentioned propyl-based esters and the reaction products were analyzed by cyclic voltammetry against copper, platinum and aluminum as working electrode to evaluate the anodic and cathodic stability, as well as possible anodic dissolution reactions in the presence of LiTFSI as conducting salt.

In both cases, the reactivity in contact with lithium metal and the anodic dissolution of aluminum, a reactivity could be observed whereupon the trihydric esters were least reactive followed by the dihydric and monohydric esters.

In absence of water and alcohols all investigated esters show no detectable reaction with lithium metal.

ACKNOWLEDGMENT

The authors want to acknowledge the German Federal Ministry for Economic Affairs and Energy (BMWi) for funding within the project FesKaBat (03ET6092E). The authors also acknowledge the analytical group of Sascha Nowak (MEET Battery Research Center, University of Münster) for all performed TXRF measurements.
Cell Heat Generation and Dissipation: From Experimentation to Application for Cell Design.
Authors: Bravo Diaz Laura , Hales Alastair , Zhao Yan , Marzook Mohamed W , Patel Yatish , Offer Gregory James
Published: February 2020

Lithium ion batteries (LIBs) are increasingly important in ensuring sustainable mobility and reliable energy supply, storing and managing energy from renewable sources [1]. Temperature is a critical factor in LIBs performance optimisation where large temperature deviations within the cell could lead to accelerated degradation and in extreme cases, thermal runaway. Thermal management has therefore become the focus of intensive research in an attempt to improve battery performance and lifespan [2-5]. Despite the growing research interest in this area, cell heat generation and heat dissipation pathways are not usually considered when designing a cell. This typically leads to cells with thermal bottlenecks prone to internal thermal gradients. With the goal of improving performance and lifetime, a two-dimensional electro-thermal model has been developed to simulate cell performance and internal states under complex thermal boundary conditions [6]. This model can be used to assess different cooling strategies and parameters such us tab position and dimensions can be optimised from the thermal performance perspective for a particular cell chemistry and geometry.

In this study, a novel experimental procedure is employed to evaluate cell heat generation and dissipation for various operation conditions. The two-dimensional electro-thermal model was employed to assess the internal temperature distribution during the measurements and to verify the heat dissipation patterns observed during the experiments. As a result, a new metric, the Cell Cooling Coefficient (CCC) is proposed to evaluate the thermal pathways of a cell cooled via its tabs.

International Energy Agency. Tracking Clean Energy Progress 2017. 1–82 (2017). doi:10.1787/energy_tech-2014-en

Bandhauer, T. M., Garimella, S. & Fuller, T. F. A Critical Review of Thermal Issues in Lithium-Ion Batteries. J. Electrochem. Soc. 158, R1–R25 (2011).

Troxler, Y., Wu, B., Marinescu, M., Yufit, V., Patel, Y., Marquis, J.A., Brandon, N.P. & Offer, G. J. The effect of thermal gradients on the performance of lithium-ion batteries. J. Power Sources 247, 1018–1025 (2014).

Hunt, I. A., Zhao, Y., Patel, Y. & Offer, G. J. Surface Cooling Causes Accelerated Degradation Compared to Tab Cooling for Lithium-Ion Pouch Cells. J. Electrochem. Soc. 163, A1846–A1852 (2016).

Khan, M. R., Swierczynski, M. J. & Kær, S. K. Towards an Ultimate Battery Thermal Management System : A Review. (2017). Batteries 3, 9 (2017)

Zhao, Y., Patel, Y., Zhang, T. & Offer, G. J. Modeling the Effects of Thermal Gradients Induced by Tab and Surface Cooling on Lithium Ion Cell Performance. J. Electrochem. Soc. 165, A3169–A3178 (2018).
Characterizing Thermodynamic Properties in Concentrated Binary Electrolytes: Combined Differential Reference Concentration Cell and Hittorf Methods
Authors: Wang Andrew , Hou Tianhong , Monroe Charles W
Published: February 2020

Accurate models of ion transport in isothermal binary solutions require measurements of various properties, including ionic conductivity, salt diffusivity, cation transference number (t+
0), and the thermodynamic Darken factor (χ). In this work a novel method is proposed to quantify composition-dependent values of χ(1-t+
0 ).

Recent studies of highly concentrated “solvent-in-salt” electrolytes suggest a strong variation of transference number with respect to composition. In fact t+
0 for electrolyte systems may double in magnitude in the highly concentrated regimes.1

Previous studies have quantified the Darken factor by assuming that t+
0 is relatively constant across the concentration range of interest. Furthermore, concentration-cell experiments typically fix arbitrary reference concentrations that may be far from the test concentration across the liquid junction. Such methods employ integral values of t+
0; the accuracy of thermodynamic properties, and thereby numerical models, may be compromised if there are substantial concentration differences and concomitant local changes in t+
0.2 An alternative approach to concentration-cell experiments would apply differential forms of the equations relating potential difference, composition, thermodynamic factor, and cation transference number.3

We propose a novel approach to concentration-cell experiments in which a matrix of liquid-junction potentials banded about a variable reference concentration is employed. When coupled with independent Hittorf-cell measurements of t+
0, this 3-dimensional surface for potential difference can be numerically fitted to reliably and accurately determine differential values of the thermodynamic factor χ across the solubility range of an electrolyte. We demonstrate this method with the electrolyte lithium hexafluorophosphate in propylene carbonate (LiPF6:PC) to determine concentration-cell liquid-junction potential (U) across a wide the solubility range. Transference-number measurements from Hittorf experiments are then used to isolate χ from differential measurements of χ(1-t+
0 ) as a function of electrolyte particle fraction (y).

Suo, L., Hu, Y. S., Li, H., Armand, M. & Chen, L. A new class of Solvent-in-Salt electrolyte for high-energy rechargeable metallic lithium batteries. Nat. Commun.
4, 1–9 (2013).

Lundgren, H., Scheers, J., Behm, M. & Lindbergh, G. Characterization of the Mass-Transport Phenomena in a Superconcentrated LiTFSI:Acetonitrile Electrolyte. J. Electrochem. Soc.
162, A1334–A1340 (2015).

Newman, J. & Thomas-Alyea, K. E. Electrochemical Systems. (John Wiley & Sons, 2004).

Figure 1
Investigating the Grain Boundary Transport and Resulting Effective Bulk Properties for Polycrystalline Solid Electrolytes
Authors: Neumann Anton , Becker-Steinberger Katharina , Danner Timo , Hein Simon , Hamann Tanner R. , Wachsman Eric D. , Latz Arnulf
Published: February 2020

All-solid-state batteries (ASSB) are candidates for the next-generation of safe and high energy density storage systems. In order to reach the full potential in terms of energy and power density the current limiting processes on the microscopic interface level as well as the macroscopic cell level need to be overcome. In this contribution, we explore the working principle of ASSBs and their interfaces in a multi-scale approach. We combine our 3D microstructure-resolved simulation tool BEST [1,2] with a supplementary thermodynamically consistent modelling framework [3] to capture the electrochemical performance and gain insight on - homogeneous solid-solid interface processes. Through this combined approach we are able to provide additional microscopic interface and bulk properties which are transferred as theory-based input parameters to our 3D microstructure-resolved simulations.

Our focus lies on the transport limiting phenomena occurring at the homogeneous solid-solid interface e.g. grain boundary resistance in the polycrystalline electrolyte. On the microscopic level we resolve the formation of space charge layers in the solid electrolyte under the influence of grains and grain boundaries. This local electrostatic perturbation of the system through the additional polarization of the crystal grain boundaries is approximated by a mean-field approach to derive an effective dielectric constant for the polycrystalline bulk solid electrolyte. The new effective material parameter depends on the magnitude of the induced polarization and therefore relies on the material specific parameters e.g. grain size, grain width, grain volume fraction. This approach provides a link between microscopic material parameters and macroscopic electrochemical transport phenomena on cell level.

Besides the effective material parameter estimation of the system, the three dimensional resolved transport through the granular solid electrolyte e.g., the grain and grain boundary transport is of special interest. In order to account for the lithium ion hopping probability between two neighbouring particles we introduce a modified interface flux at the grain interfaces. By explicit modelling of the polycrystalline electrolyte, the experimentally observed impedance characteristics are reproduced and identified. In an extended study for oxidic garnet type systems the correlation between grain size and grain impedance as well as the varying transport properties between boundary and core phase are presented. The comparison between simulations and experiments demonstrates the importance of interfacial processes and gives directions for the development of future ASSBs.
Prediction of Large Format High Power Cell Performance Using NTG Model
Authors: Manikandan Balasundaram , Lain Michael J , Widanage Widanalage Dhammika , Kendrick Emma
Published: February 2020

Accurate prediction of cell performance using electrochemical parameters has always been a challenge in terms of computational complexity and collection of parameters for individual cell components (such as cathode, anode and electrolyte). In construction of a completely physics based model, the parameterisation is tedious and extremely time consuming. In order to save time and maintain accuracy, an alternate mathematical model which demands less experimental inputs especially from full cell alone is of interest in this study. In addition, the model which offers scope to manipulate the geometrical features such as tab positions and cell dimensions to further optimise the cell performance at minimal computational time is desirable. NTG model is a semi empirical model which predicts the transient behaviour of lithium ion batteries. In this study, two significant full cell parameters namely effective conductance and open circuit voltage are determined for a high power cell by stepped pulse experiments over a wide range of operating temperatures between -25°C and 50°C. Other parameters such as cell thermal conductivity, specific heat capacity and density are also determined. Additional heat balance equations are incorporated to simulate the thermal behaviour of cell. The model is constructed using partial differentiation equations in COMSOL and solved across a representative 3D geometry. Interestingly, the electrochemical performance curves and the cell surface temperature from simulations are quite close to that of experiments. The feasibility of potential, current density and temperature distribution in three dimensions in this model give better insights into the underlying battery physics. Although the diffusion of lithium ions is overlooked in this model for simplicity, the model offers the advantage of faster simulations for high power cells where the electrode loading is lesser.
(Invited) Electrochemical “Zinc-Ion” Storage at Nanostructured Manganese Oxides: Mechanistic Insights from 2D Interfaces to Advanced 3D Electrode Architectures
Authors: Long Jeffrey W. , Ko Jesse S. , Sassin Megan B. , Chervin Christopher N. , Parker Joseph F. , Jeon Seokmin , So Christopher R , Rolison Debra R.
Published: February 2020

Alkaline Zn/MnO2 cells remain a popular energy-storage technology due to their low cost and benign components, yet they lack the long-term rechargeability and high-power capability required in many present and emerging applications. The benefits inherent to the coupling of zinc and manganese oxide (MnOx) electrodes can be translated to a new generation of rechargeable “zinc-ion” batteries that incorporate mild-pH Zn2+-containing electrolytes. By pairing such electrolytes with particular nanostructured forms of MnOx that undergo reversible Zn2+-based redox reactions, the rechargeability of Zn/MnOx systems can be extended to hundreds or thousands of cycles. We are exploring two particular MnOx polymorphs—layered, birnessite-type and cubic-spinel ZnMn2O4—for zinc-ion storage, where these oxides are expressed as nanoscale coatings on 3D carbon nanofoam (CNF) architectures. Such electrode designs enable high oxide-normalized capacity delivered at moderate-to-high rates and over hundreds of charge–discharge cycles. When Na+ or Li+ salts are added to the Zn2+-based aqueous electrolyte, pseudocapacitive reactions at the MnOx become active to provide pulse-power functionality at time scales approaching those for electrochemical capacitors [1]. Electrochemical charge storage in zinc-ion electrolytes may follow multiple pathways, including direct Zn2+ insertion/association at MnOx or via proton-insertion reactions that drive the formation of Znx(OH)y(SO4)z salts at the MnOx surface. We use ex situ characterization (diffraction, spectroscopy, and microscopy) of electrochemically conditioned MnOx–CNF electrodes to show that the latter reaction is dominant for birnessite-type MnOx, where the reversibility of Znx(OH)y(SO4)z formation/dissolution is promoted by the pore–solid architecture of the CNF [2]. These findings are further confirmed by scanning-probe microscopy and quartz-crystal microbalance techniques at planar MnOx–carbon electrodes that mimic the interfaces in MnOx–CNF. Insights from these investigations inform the design of advanced electrode architectures for high-performance, rechargeable zinc-ion batteries.

[1] “Combining Battery-Like and Pseudocapacitive Charge Storage in 3D MnOx@Carbon Electrode Architectures in Zinc-Ion Cells.” J.S. Ko, M.B. Sassin, J.F. Parker, D.R. Rolison, and J.W. Long, Sustain. Energy Fuels, 2 (2018) 626–636.

[2] J.S. Ko, M.D. Donakowski, M.B. Sassin, J.F. Parker, D.R. Rolison, and J.W. Long, MRS Comm., in press (2019).
The Study of Nicofe-Ternary Layered Double Hydroxide As Electrode for Supercapacitors
Authors: Ni Chung Sheng , Chen Han-Yi , Huang Jin-Hua
Published: February 2020

The transition metal hydroxides are well-known electrode materials for supercapacitors (SCs) due to their high theoretical specific capacitances. Nevertheless, low electronic conductivity of those hydroxides limits their real applications. To improve the electronic conductivity, ternary NiCoFe layered double hydroxides (LDHs) with different composition ratios were synthesized via a simple electrodeposition method in this study.

The microstructure and morphology of the as-prepared NiCoFe LDH samples were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Comparing with the binary NiCo LDHs, the ternary NiCoFe LDHs show a different nanosheet structure which is beneficial to provide high specific surface area. Among these samples, the best NiCoFe LDH has performed a specific capacitance of ~ 950 F/g at 5 mV/s and a high rate retention of ~50 % at 500 mV/s, owing to the improvement in conductivity which was mainly attributed to the addition of Fe ions. The electrochemical impedance spectra (EIS) of all LDH samples were also measured and analyzed. This finding reveals the possibility of exploring the NiCoFe LDH as an effective electrode material for high-performance SCs.
A Water-in-Salt Electrolyte for High-Voltage Aqueous Sodium-Ion Batteries
Authors: Reber David , Kühnel Ruben-Simon , Battaglia Corsin
Published: February 2020

The inherent safety and potential low cost make rechargeable batteries based on aqueous electrolytes a promising option for large-scale energy storage for grid applications. So far, operational voltages of aqueous batteries have been too low to enable market penetration due to the narrow electrochemical stability window of water (~1.23 V). Using a highly-concentrated aqueous sodium bis(fluorosulfonyl)imide (NaFSI) (35 molal) electrolyte we recently reported a stability window of 2.6 V [1] and further developed a highly-concentrated ternary aqueous sodium-ion electrolyte which is robust against crystallization even at low temperatures and allows long term cycling of full-cells well below 0 °C. A 2 V class cell, based on this electrolyte, NaTi2(PO4)3 [2] and Na3(VOPO4)2F [3], displays excellent cycling stability between 30 and -10 °C with an energy density of 64 Wh kg-1, based on the active masses of both electrodes. This is almost twice as high as that of previously reported aqueous sodium-ion batteries [4]. At elevated temperatures however, the FSI-anion is susceptible to hydrolysis. As most so called water-in-salt electrolytes reported to date are based on fluorinated sulfonylimides we investigated LiFSI and NaFSI as model systems over a wide concentration and temperature range. We find that highly concentrated NaFSI electrolytes are significantly more stable than their lithium analogues. For 35m LiFSI solutions we observe complete degradation after storage at 60 °C for one week, whereas 35m NaFSI only exhibits a small decrease in pH. We suggest that FSI-destabilizing, strong anion-cation interactions in such highly concentrated electrolytes are cation dependent and relate the stability of the anion to the charge density of the cation.

References:

Kühnel, R. S.; Reber, D.; Battaglia, C., A High-Voltage Aqueous Electrolyte for Sodium-Ion Batteries. ACS Energy Lett.
2, 2005 (2017).

Li, Z.; Young, D.; Xiang, K.; Carter, W. C.; Chiang, Y.-M., Towards High Power High Energy Aqueous Sodium-Ion Batteries: The NaTi2(PO4)3/Na44MnO2 System. Adv. Energy Mater.
3, 290 (2013).

Qi, Y.; Mu, L.; Zhao, J.; Hu, Y. S.; Liu, H.; Dai, S., Superior Na-Storage Performance of Low-Temperature-Synthesized Na3(VO(1-x)PO4)2F(1+2x) (0≤x≤1) Nanoparticles for Na-Ion Batteries. Chem. Int. Ed.
54, 9911 (2015).

Kumar, P. R.; Jung, Y. H.; Wang, J. E.; Kim, D. K., Na3V2O2(PO4)2F-MWCNT nanocomposites as a stable and high rate cathode for aqueous and non-aqueous sodium-ion batteries. Power Sources
324, 421 (2016).
(Invited) Ionic Liquid Electrolytes and Ionogel Composites That Enable High Capacity Anodes for Lithium and Sodium Batteries
Authors: Forsyth Maria , Howlett Patrick C , MacFarlane Douglas R. , Mecerreyes David , Girard Gaetan , Ferdousi Shammi Akter , Armand Michel , Wang Xiaoen
Published: February 2020

Traditional electrolytes currently used for Li-ion and Na-ion devices are not compatible with higher energy-density anodes required for next generation devices, such as Li metal and Na metal anodes. In addition, there is now a recognition that operation at elevated temperatures is desirable for some applications. Therefore, new electrolyte materials are currently actively being investigated for beyond Li-ion technologies. It has recently been shown that, by using an ultra-high concentration of lithium or sodium salt in an ionic liquid (or indeed some organic solvents),it is possible to achieve stable cycling of Li metal and Na metal anodes, often at high rates and current densities, and even in the presence of water. These electrolytes indicate a decoupling of the alkali metal ion dynamics from the bulk with tLi+ or tNa
+ transport numbers approaching or even exceeding 0.5. We will discuss the structure and transport in these superconcentrated IL systems and the importance of clustering and structural rearrangement in the transport mechanism of the alkali metal cation.

It has also been demonstrated that polymerized ionic liquids, such as poly(diallyldimethylammonium) (PDADMA), with either TFSI or FSI counterions, are capable of dissolving even higher concentrations of lithium salt leading to highly conductive solid electrolytes. These materials have high tLi+ and improved mechanical properties and also enable stable Li metal cycling, thus offering exciting opportunities for all solid state lithium batteries. These materials will also be discussed in terms of their phase behavior, conductivity and electrochemical behavior.