bluuebunny/crossref_metadata_2025 huggingface dataset:
Battery Functionality and Reactivity of a Cathode for Magnesium Ion Battery
Authors: Suto Koji , Zhang Ruigang , Mohtadi Rana
Published: February 2020

Post lithium ion battery is highly demanding energy storage for smaller scale as stationary use to greater scale as grid storage, and vehicle use as well. Magnesium ion battery with metal magnesium as an anode has been investigated over decades because of its high theoretical capacity of magnesium (3833 mAh cm3) and relatively lower potential (0.7 V vs lithium) for naturally abundant mineral resources in “multivalent” metals with less risk on forming dendritic deposits [1]. After over a decade of finding of stable and reversible electrolyte based on Grignard agent such as APC [2], our finding of magnesium monocarborane [3] opened next door toward high energy density by its wider potential window up to 3.7 V and high current density more than 1mS cm-1, without corrosive issue which is intrinsic to conventional electrolytes containing chlorine.

Although of many efforts for electrolytes and electrodes, the battery system has lack of cathode capable of providing high potential and / or capacity with stable performance over numbers of cycles in charge and discharge, to takeover Li ion battery. Recently some challenges proved custom approach for magnesium ion effective to certain extent; eg. C60 [4] works as a mimic of cluster aspect of highly reversible Chevrel Mo6S8, and spinel Ti2S4 [5] presents the design of host framework with “soft” anion and ionic path.

In this study we approach to new insights into active materials by means of charge transfer. Interfacial analysis such as electrochemical impedance, XPS, etc., to the most established cathode, Chevrel phase Mo6S8 [1] in contact with MMC electrolyte gives some key factors of highly reversible cathode. Besides, our new approach for a cathode active material and its battery performance will be introduced for the next step of the reaction design.

References:

[1] J. Muldoon, C. B. Bucur, and Th. Gregory, Chem. Rev.
2014,
114, 11683.

[2] D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, E. Levi, Nature
2000, 407, 724.

[3] O. Tutusaus, R. Mohtadi, T. S. Arthur, F. Mizuno, E. G. Nelson, Y. V. Sevryugina, Angew. Chem. Int. Ed.
2015, 54, 7900.

[4] R. Zhang, F. Mizuno, L. Chen,, Chem. Commn..
2015, 51, 1108.

[5] X. Sum, P. Bonnick, V. Duffort, M. Liu, Z. Rong, K. A. Persson, G. Ceder, an L. F. Nazer, Energy Environ. Sci.
2016, 9, 2273.
Enhanced Magnesium-Ion Charge Transport and Storage within Layered Vanadium Pentoxide-Poly(ethylene oxide) Nanocomposites
Authors: Rhodes Christopher , Perera Sanjaya , Archer Randall
Published: February 2020

Cathode materials that have high reversible magnesium-ion capacities and reasonable operating voltages are needed for rechargeable magnesium batteries. Layered materials are a particularly promising class of materials for electrochemical Mg-ion charge storage, however additional research is needed to increase Mg-ion capacities, improve capacity retension upon cycling, and understand the nature of interlayer interactions. Our work has investigated hydrated vanadium pentoxide (V2O5) xerogels that incorporate poly(ethylene oxide) (PEO) between the layers as an approach to improve Mg-ion charge storage and control interlayer structure and dynamics. V2O5 nanosheets were grown in the presence of PEO to allow inimate interaction with the V2O5 layers and allow control of the PEO content in V2O5-PEO nanocomposites. X-ray diffraction and high resolution transmission electron microscopy demonstrate that the interlayer spacing between V2O5 layers was increased by incorporating PEO within the layers. The Mg-ion diffusion coefficient was shown to be strongly dependent on not only interlayer spacing, but also interlayer composition. With specific polymer compositions, Mg-ion diffusion within V2O5-PEO nanocomposites was significantly increased compared with V2O5 xerogels. Raman spectroscopy supports that the polymer interacts with the V2O5 lattice resulting in interlayer water that is less strongly bound to the V2O5 lattice. The V2O5-PEO nanocomposite with specific PEO compositions exhibited significantly improved Mg-ion specific capacity compared with V2O5 xerogels and showed improved capacity retension upon cycling. Our work supports that in addition to interlayer spacing, controlling interlayer interactions between V2O5 layers, PEO, H2O, and Mg-ions allows significant improvements in Mg-ion charge transport and storage. The design of layered materials with controlled interlayer compositions provides a novel route to significantly improve charge storage and transport in layered materials.
Electrode Surface Chemical Effects on Lithium Ion Intercalation: Insights from First-Principles Simulations
Authors: Pham Tuan Anh , Ong Mitchell T. , Kweon Kyoung , Samanta Amit , Lordi Vincenzo , Pask John E.
Published: February 2020

Understanding Li ion intercalation at the electrode-electrolyte interface is critical for predicting and optimizing the performance of lithium-ion secondary batteries (LIB). In this work, we investigate the impact of the electrode surface chemical composition, in particular the edge termination of graphite anodes, on the energetics and rate of intercalation/de-intercalation and the related Li ion solvation structure near the interface. We carried out extensive first-principles molecular dynamics simulations of a prototypical electrolyte consisting of ethylene carbonate (EC) organic solvent containing dissolved LiPF6 salt, in contact with armchair- and zigzag-oriented graphite surfaces. By considering a variety of surface terminations, including H, 1:1 H/OH, and carbonyl, we find that surface composition shows significant effects on the energetics of Li+ intercalation. Specifically, the carbonyl-terminated surfaces exhibit a significantly larger energy barrier for Li+ insertion due to a complex interplay between the surface polarization, electronic charge transfer and the formation of pseudo-solvation shells involving surface chemical species, in sharp contrast to the H and 1:1 H/OH terminations. This work extends generally to a variety of solid/liquid interfaces in LIB, where surface chemical interactions play an important role in kinetics.
Molecular Design of Conjugated Lithium Carboxylates As Negative Electrodes for Lithium-Ion Battery
Authors: Thiam Amadou , Toumieux Sylvestre , Frayret Christine , Becuwe Matthieu
Published: February 2020

During the last twenty-five years Lithium Ion Batteries (LIBs) have expanded their landscape in large-scale applications and are now well positioned to achieve the Electrical Vehicle (EV) horizon, thus lessening our dependence towards fossil fuels. Among all possible negative electrode materials used in commercial LIBs, graphite is the most employed due to its lowest operating potential and to its excellent cyclability. However, such an operating potential (~ 0.1 V vs. Li+/Li) induces considerable risk of decomposition associated with lithium dendrite growth. Coupling many advantages in one material, conjugated lithium carboxylates can be seen as one of the best alternative to overcome these issues and thus became serious candidates to supplant LTO in the future. However, employment of organic material remains at an early stage compared with classical anode materials. A step forward deep structure-property relationship has clearly to be performed to reach the target of sustainable energy storage. The main difficulty of such approach nests in the combination of different fields, e.g. organic synthesis, material science and solid-state electrochemistry, all of them having an impact on the performances (e.g.material particle size on activity/conductivity or electrolyte on capacity. Nevertheless, electrochemical activity remains primarily governed by the molecular structure which is the starting point of the electrode material conception. As an example of the importance of molecular design on electrode performances, we first studied the impact on the rate capability of the stabilization center using naphthalene (Fédèle et al., JES, 2014) and perylene Fédèle et al., J. Mat. Chem. A, 2014) cores and very recently the incidence of the conjugation distance between two carboxylates using a layered material based on a 4,4’-biphenyl unit (Fédèle et al., Chem. Mater., accepted).

In order to explore in details the impact of the delocalization extent on electrochemical performances of conjugated dilithium carboxylate, we focused on substituted or bridged biphenyl-based materials using a coupled theoretical/experimental approach. Thanks to these investigations, we clearly showed a dramatic influence of key structural parameters modulating (or tuning) the electron movement ability and define new trends to control the redox potential, reversibility and rate capability by adding selectively atoms on the aromatic backbone. This work thus opens new perspectives towards the understanding of the reactivity of such family.

Figure 1
Effect of Material Anisotropy on the Mechanical Response of Protective Layers for Lithium Metal Anodes
Authors: Chadwick Alexander F. , Thornton Katsuyo
Published: February 2020

A critical challenge in the development of safe, long-lasting secondary batteries with lithium metal anodes is protecting the surface of the anode to prevent dendrite formation during charging1 or to minimize interactions between the anode and active species in the electrolyte.2,3 One approach is to place a protective layer in the cell, such as a coating on the anode itself or as a free-standing membrane material, which can inhibit many of the mechanisms that lead to failure of the lithium metal anode. These layers must be mechanically robust such that they do not fail over the course of many cycles. However, these materials experience stress during cycling, which can lead to mechanical failure at high current densities. While such phenomena have been examined in certain cathode materials, such as LiCoO2,4 it has yet to be investigated in depth for anode protective layers. The stress arises from gradients in the lithium concentration that lead to the formation of eigenstrains. Here, we present a continuum-scale model to examine the effect of anisotropy in mechanical and transport properties on eigenstrains in protective layer materials. The model solves for the mechanical equilibrium of the layer, with the anisotropic linear elasticity tensor as well as the concentration-dependent anisotropic eigenstrain in the material based on the steady-state concentration profile. The von Mises stress is calculated as a function of the anisotropic properties and applied current. This stress can be compared to the yield stress of the protective layer material to determine whether it is sufficiently robust for many charge/discharge cycles of the lithium metal anode. The presented work will cover a range of cases from single-crystal domains to polycrystalline films with varying levels of anisotropy. By examining the peak von Mises stress as a function of the applied current density, the model will predict design guidelines for the relevant material parameters.

References

1. Y. Cao, X. Meng, and J. W. Elam, ChemElectroChem, 3, 858–863 (2016).

2. R. Cao, W. Xu, D. Lv, J. Xiao, and J.-G. Zhang, Adv. Energy Mater., 5, 1402273 (2015).

3. S. E. Doris, A. L. Ward, P. D. Frischmann, L. Li, and B. A. Helms, J. Mater. Chem. A, 4, 16946–16952 (2016).

4. H. Wang, Y.-I. Jang, B. Huang, D. R. Sadoway, and Y.-M. Chiang, J. Electrochem. Soc., 146, 473–480 (1999).
Electrochemical Assessment of Li4Ti5O12 Li-Ion Battery Anodes
Authors: Rashid Muhammad , Sahoo Asit , Sharma Yogesh , Gupta Amit
Published: February 2020

Lithium titanate oxide (Li4Ti5O12, LTO) has been receiving significant attention as alternative over graphitic anode for Li-ion batteries (LIBs) due to its zero strain property, no lithium plating at quick charging and higher thermal stability [1-2]. The Li/Li+ potential plateaus of LTO anodes lies around 1.55 V [2-3] which forms 2V–class batteries when used with high voltage cathodes, i.e., LiMn2O4, LiCoO2 and LiNi1/3Mn1/3Co1/3O2. Several studies have been conducted on the synthesis, characterization and electrochemical performance assessment of LTO as potential anode material for Li-ion battery technologies [1-4]. However, the effect of design and cell parameters on the discharge capacity and electrochemical behavior of the LTO anodes has not been reported in the literature so far. Numerical simulations using mathematical models are widely used as an alternative to carry out detailed parametric analysis, which can assist in quantifiable implications of cell variables on the charge-discharge capacity of LIBs. Therefore, the objectives of the present study are focused on the investigation of intercalation-deintercalation phenomena in LTO electrodes (against Li-foil) through experiments and simulations. The experimental work consists of synthesis, characterization and electrochemical performance assessment including open-circuit potential (OCP) measurement of the LTO material. Furthermore, lithium diffusivity in the solid matrix of the LTO electrode is also gauged through galvanostatic intermittent titration technique (GITT). The measured cell variables are used as input to the numerical simulations for Li/LTO half-cells which utilize the Doyle’s [5] pseudo-two-dimensional cell model. Figure 1 shows numerically simulated cell potential vs. normalized capacity which indicates departure of cell voltage from OCP due to lithiation and delithiation in LTO electrode. This study will lead to quantification of electrochemical performance, rate capability and optimum cell parameters for synthesized LTO as anode material for LIBs.

N. Nitta, F. Wu, J.T. Lee and G. Yushin, “Li-ion battery materials : present and future”, Mater. Today, 18, 252 (2015).

Y. Wang, L. Gu, Y. Guo, H. Li, X. He, S. Tsukimoto, Y. Ikuhara and L. Wan, “Rutile-TiO 2 nanocoating for a high-rate Li4Ti5O12 anode of a Li-ion battery”, J. Am. Chem. Soc., 134, 7874 (2012).

C. Zhang, Y. Zhang, J. Wang, D. Wang, D. He and Y. Xia, “Li4Ti5O12 prepared by a modified citric acid sol-gel method for Li-ion battery”, J. Power Sources, 236, 118 (2013).

A.S. Prakash, P. Manikandan, K. Ramesha, M. Sathiya, J. Tarascon, A.K. Shukla and D.P.J. Verne, “Solution-combustion synthesized nanocrystalline Li4Ti5O12 as high-rate performance Li-ion battery anode”, Chem. Mater., 22, 2857 (2010).

M. Doyle, T.F. Fuller and J. Newman, “Modeling of galvanostatic charge and discharge of the lithium/polymer/insertion cell”, J. Electrochem. Soc., 140, 1526 (1993).

Figure 1
Electroactive Materials Design Strategies Toward Increased Electrical Conductivity: Impact on Electrochemistry
Authors: Marschilok Amy C , Takeuchi Esther S , Takeuchi Kenneth J
Published: February 2020

Energy storage materials remain important due to their ability to store electricity for many applications including aerospace, transportation, portable electronics, and biomedical devices. Full utilization of materials requires fast transport of both ions and electrons to all regions of the electrode. Several approaches have been utilized to facilitate ion diffusion including dimension reduction, morphology control, and synthesis of layered and tunneled structures, however, electron access must also be considered. Low electrical conductivity can limit active material utilization, especially at high rates, and may be a cause of capacity fade.

One approach to address the low electrical conductivity of cathode materials is to utilize composite electrodes that contain conductive media, most often carbon. While commonly employed, this strategy is imperfect, as inhomogeneous dispersion of the active material in the conductive additive results in incomplete electrical contact to all particles in the electrode. Encapsulation of individual active material particles with a carbon coating can be more effective for providing electrical contact to each particle, however have the disadvantages of additional synthesis steps and increased production cost. An alternative strategy to approach an ideal electrode that we have been exploring is the use of bimetallic material systems. In this approach, the active material particles are electrically connected as they generate a conductive network in-situ on initiation of reduction. Bimetallic cathode materials offer the opportunity for conductive matrix formation via reduction displacement reactions that result in the formation of metal nanoparticles providing the electrical connections.

The investigation of bimetallic materials and the formation of electrically conductive pathways has included exploration of metal oxide and metal polyanion type structures including phosphate and diphosphate moieties. Additionally, composites containing bimetallic materials have been explored. The impact of this strategy on delivered capacity and capacity retention will be discussed.
Exceptional Lithium Intercalation Capacity of Incommensurate Graphene Foam in Rechargeable Batteries
Authors: Paronyan Tereza M. , Thapa Arjun Khumar , Sherehiy Andriy , Jasinski Jacek B. , Jangam John Samuel Dilip
Published: February 2020

Development of high capacity Lithium battery anode materials will have a profound and direct impact on current commercial and emerging markets such as portable electronics, electric vehicles and electric grid storages.

 Graphite’s capacity of intercalating lithium in rechargeable batteries is limited (theoretically, 372 mAh/g) due to low diffusion of lithium atoms within commensurately-stacked infinite graphene layers. Graphene foam with highly enriched incommensurately-stacking layers is grown using Chemical Vapor Deposition (CVD) method and applied as an active electrode in rechargeable batteries. Raman spectroscopy is used to estimate the fraction of incommensurately-stacking layers in a bulk material. ~90% incommensurate graphene foam is demonstrated up to 1540 mAh/g reversible specific capacity at 100 mA/g current density stable throughout hundred cycles with 75-100% Coulombic efficiency. C-rate testing of the electrochemical cells exhibit stability under high current densities which makes these cells feasible.

 XRD, XPS and Raman analysis of graphene anodes show that lithium atoms highly intercalate within weakly interacting incommensurately-stacked graphene structure, followed by a flexible rearrangement of layers for a long-term stable cycling. We have tested several samples with various incommensurateness degree and found that specific capacity is enhanced when commensurately-stacking order of graphene layers is reduced in an anode material1. The incommensurately-stacked infinite layer graphene cab be considered as a “graphite-like” structure with weakened interplanar interaction which may exhibit exceptionally high lithium capacity of 1116 mAh/g with LiC2 stoichiometry. New intercalation model of multilayer graphene is considered, where capacity varies with N number of layers, resulting LiN+1C2N stoichiometry in which the finite layers of graphene can demonstrate higher capacity, achieving a maximum of 1674 mAh/g in bilayer configuration. An effective capacity increase over six times compared to commonly use commercial graphite battery cells promises the feasibility of the rapid development of lightweight, cost-efficient and high energy density secondary batteries.

Paronyan, T. M. et al. Incommensurate Graphene Foam as a High Capacity Lithium Intercalation Anode. Sci. Rep. 
6, 39944; doi: 10.1038/srep39944 (2016).
High-Performance Rechargeable Lithium-Sulfur Dioxide Batteries Exploiting Conventional Carbonate-Based Electroyltes
Authors: Park Hyeokjun , Lim Hee-Dae , Lim Hyung Kyu , Bae Youngjoon , Kim Hyungjun , Kang Kisuk
Published: February 2020

Shedding new light on conventional primary batteries sometimes inspires new chemistry adoptable for rechargeable batteries. Recently, a primary lithium-sulfur dioxide battery, which offers a high energy density and a long shelf-life, was successfully renewed as a promising rechargeable system exhibiting significant merits over the lithium-oxygen chemistry such as small polarization and good reversibility.1 Here, we demonstrate, for the first time, that the reversible operation of the lithium-sulfur dioxide battery is also possible exploiting conventional carbonate-based electrolytes. Even though carbonate-based electrolytes possess advantages such as high ionic conductivity and good electro/chemical stability and have thus been widely used in commercial lithium-ion batteries, they have not been used in metal–air batteries because of the occurrence of serious side reactions. The attempt to use carbonate-based electrolytes during the early development of rechargeable lithium–oxygen and sodium–oxygen batteries failed, yielding significant side reaction products; thus, appropriate charging process could not be achieved.2,3 The organic carbonate was highly vulnerable to chemical attacks by gas radicals generated during the discharge process. This finding has led to the general perception that carbonate-based electrolytes cannot be considered for metal–gas batteries. However, theoretical and experimental studies reveal that the SO2 electrochemistry is highly stable in the carbonate-based electrolytes enabling the reversible formation of Li2S2O4 in contrast to lithium-oxygen batteries. The use of the carbonate-based electrolyte leads to the remarkable enhancement of power and reversibility with much improved compatibility with lithium metal; furthermore, the optimized lithium-sulfur dioxide battery with catalysts achieves the outstanding cycle stability over 450 times with 0.2 V polarization, which is one of the highest efficiencies reported for metal-gas batteries. This study highlights the potential promise of rechargeable lithium-sulfur dioxide chemistry along with the viability of the conventional carbonate-based electrolytes in metal-gas rechargeable systems. We expect this finding to open up a further opportunity for the lithium–sulfur dioxide chemistry as a promising next-generation rechargeable battery and spur vigorous discussions on the role of the electrolyte in metal–air batteries.

Reference

Lim. H. -D. et al. Ange. Chem.
127, 9799 (2015).

Freunberger, S. A. et al.
J. Am. Chem. Soc.
133, 8040 (2012).

Kim. J. et al. Phys. Chem. Phys. Chem.
15, 3623 (2013).
Understanding Capacity Fading of LiNi0.8Co0.15Al0.05O2 Via Long-Term Operando X-Ray Diffraction Studies
Authors: Liu Hao , Karki Khim , Stach Eric A. , Chapman Karena W , Chupas Peter J
Published: February 2020

Layered lithium transition metal oxides are promising high-capacity cathode materials for Li-ion batteries. However, capacity fading has restricted the practical capacity to less than 70% of the theoretical capacity. Higher initial capacity can be achieved by charging to a higher voltage, yet this initial gain in capacity is quickly offset by the rapid fade in capacity. Understanding the capacity fading mechanism will help develop strategies to mitigate this problem. We used operando X-ray powder diffraction to follow the reactions of the layered LiNi0.8Co0.15Al0.05O2 over extended charge-discharge cycles at a slow current rate. The operando result shows that the capacity loss can be explained by the heterogeneity developed in the electrode after extended charge-discharge cycles.
Chemical, Morphological, and Structural Tuning of Tunnel Manganese Oxides for Intercalation Batteries
Authors: Byles Bryan , Pomerantseva Ekaterina
Published: February 2020

In this work, we investigate the effect of tunnel dimension, material morphology, and structural water content on the performance of two tunnel structured manganese oxides in intercalation batteries. Tunnel manganese oxides represent an attractive family of materials for intercalation-based energy storage due to their open crystal structures consisting of well-defined structural tunnels that allow for the reversible insertion/extraction of charge-carrying ions, as well as their low cost, low environmental impact, and high electrochemical activity. Facile hydrothermal methods can be used to synthesize tunnel manganese oxides, which have the general formula AxMnO2, where “A” is a stabilizing cation present within the structural tunnels built from MnO6 octahedra.

We focus on comparing the performance of two tunnel manganese oxides with square tunnel structures, α-MnO2 (K0.11MnO2), which contains tunnels of 2x2 octahedra dimension, and todorokite MnO2 (Mg0.20MnO2), which contains tunnels of 3x3 octahedra dimensions. When tested as intercalation electrodes in Na-ion batteries, we find that the material with smaller structural tunnels, α-MnO2, achieved a higher initial capacity of 330 mAh g-1­, while todorokite MnO2, which contains larger 3x3 octahedra tunnels, achieved a capacity of 157 mAh g-1. However, the larger tunnel structure proved to be more stable in a Na-ion battery, demonstrating superior capacity retention, as well as superior rate performance. These results suggest that although smaller tunnels may initially show higher capacity, larger tunnels are preferable for superior electrochemical stability. Further, the effect of material morphology is also shown by synthesizing todorokite MnO2 with both a platelet and a nanowire morphology. In Li-ion batteries, the nanowire morphology exhibited a 30% higher capacity retention after 100 cycles, demonstrating the advantage of a nanowire morphology in terms of enhanced cycling stability. Moreover, the effect of structural water in todorokite MnO2 (0.42 H2O molecules per Mn) is discussed, elucidating the role of structural water on ion insertion of into tunnel structured materials. Lastly, we discuss the effect of controlling the electrochemical potential window used during cycling, the trade off between capacity and capacity retention, and how the stability of these materials can be improved. This work describes the role of tunnel size, ionic content, and material morphology on the behavior of tunnel manganese oxides and thus provides insight into tailoring of tunnel structured materials for intercalation batteries.
Molecular Weight Effect of Poly(Acrylic Acid) on the Silicon Anode of Lithium-Ion Batteries
Authors: Hu Bin , Zhang Jingjing , Zhang Shuo , Zhang Zhengcheng , Zhang Lu
Published: February 2020

Silicon (Si) has been regarded as a promising anode material for the lithium-ion batteries due to its high theoretical specific capacity about 4200 mAh/g and low costs. However, during the lithiation/delithiation processes, the Si particle experiences repeated expansion in size up to 300 %, which leads to associated particle pulverization, electrode delamination, and destabilization of solid-electrode interface (SEI) layer. The conventional polyvinylidene fluoride (PVDF) binder has poor cycling performance on the Si anode and a lot of efforts are currently focused on flexible and polar polymeric binders such as carboxymethyl cellulose (CMC), alginate, and poly(acrylic acid) (PAA), etc. While there have been many promising progress reported regarding those binders, very little work has been conducted to explore the relationship of the molecular properties and cell performance. In this report, we have attempted to probe one very simple polymer property, molecular weight, using PAA binders and try to correlate this particular variation to the performance of the silicon lithium-ion cells. Specifically, five commercially available PAA samples with various molecular weights ranging from 5k to 450k Dalton were procured. Their molecular weights were further confirmed by gel permeation chromatography (GPC) after pre-treatment of methylation. The viscosity of the lithiated PAA aqueous solutions with a constant concentration of 15% was measured by rheometer. It is overserved that higher molecular PAA sample affords higher viscosity, which is one desirable property for binders. Those binders were then evaluated in silicon half cells, where the anodes were consisted of 10 % lithiated PAA, 73 % Hitachi MagE, 15 % Si nanoparticles (70-130 nm) and 2 % Timcal C45. According to the results, cells with different PAA binders indeed showed different cycling performance. It is noticed that the cells with higher molecular weight PAA binders could afford higher initial specific capacities and better capacity retentions. While the fundamental reason is still not fully understood, we are conducting various characterizations to pursue the insights. DFT calculations are conducted to estimate the conformations, which can be used to estimate the chain length of PAA polymers with different molecular weights. We believe the chain lengths could be an important indicator to quickly evaluate the compatibility to silicon particles with various sizes.

Figure 1
Electroless Deposition of Sn on Carbon Cloth for Use As Anodes in Lithium Ion Batteries
Authors: Kalu Egwu Eric , Watson Venroy George , Telama Wete
Published: February 2020

Graphite (372 mAh/g) powder is currently used as Li-battery anode material but urgent need exists to replace it with materials with higher capacity, energy and power density. Investigation of Sn (991mAh/g) as an alternative to graphite has been explored through many approaches which has not been able to address the large volume expansion (fabrication related) and performance limitations associated with Sn during cycling1,2.  In this work, by using electroless deposition method, we demonstrate that a new approach of fabricating high performing Cu-Sn alloy for lithium battery anode with high capacity, power density and long cycle life is feasible. In our approach, Cu was electrolessly deposited on carbon cloth followed by immersion of the Cu-plated cloth in a Sn bath for partial displacement of the Cu and subsequent formation of Cu-Sn alloy. The use of a woven fabric as a substrate provides pathways for flow of electrons while its pores accommodate the expansion of tin with minimal performance loss. Our electroless approach is also applicable for graphite particles. The Cu-Sn alloy deposited on carbon over various times was used in Coin cell with Li metal as counter electrode. The open circuit voltage of freshly fabricated cell varied from 2.02V (for pristine carbon cloth) to 3V (for Cu-Sn plated carbon cloth). First cycle specific discharge capacity from open circuit voltage to 0.007V for our new electrodes varied between 561 mAh/g to 656 mAh/g based on the mass of Cu-Sn deposited on the cloth. The results of the cell’s performance evaluation as a function of Sn Cu displacement time will be presented.

Figure 1
Porous Structured SnO2 Nanofibers and Nanotubes As Anode Materials for Sodium-Ion Batteries
Authors: Kizil Huseyin , Duran Ercin Cagan
Published: February 2020

Sodium has similar electrochemical properties compare to lithium besides its abundancy on earth. Sodium-ion batteries are promising cost-effective alternatives to lithium-ion batteries for large scale applications where weight and energy density are of minor importance However, poor cycling stability and lower energy density of current sodium-ion batteries hinder their practical applications. Due to its excellent sodium ion storing capacity, tin dioxide (SnO2) emerged as a good candidate as anode material for sodium-ion batteries. However, large volume expansion upon cycling and subsequent pulverization of the active material is a great concern. In this study, novel tin dioxide porous nanofibers and nanotubes (SnO2 PNFs and SnO2 PNTs) were synthesized by electrospinning and subsequent heat treatment of a mixture containing different amount of mineral oil. Results indicated that low-porosity nanofibers led to higher capacity and improved cycling stability when compared to high-porosity nanotubes. Electrochemical performance studies indicated that porous nature of SnO2 PNFs and SnO2 PNTs anodes enabled to achieve good electrochemical performance, including relatively high capacity (311.8 mAhg-1 and 225 mAhg-1), large Coulombic efficiency (93.1% and 83.62%) and good capacity retention (79.2% and 79.47%) after 25th cycle, respectively.
Anode Surface Evolution in Aqueous Sodium-Ion Batteries
Authors: Zhan Xiaowen , Shirpour Mona
Published: February 2020

Aqueous sodium-ion batteries may solve the cost and safety issues associated with the energy storage systems for the fluctuating supply of electricity based on solar and wind power. Compared to their lithium counterparts, aqueous sodium-ion batteries offer multiple advantages including more earth abundant sodium, cheaper electrode materials and electrolyte solutions as well as less costly manufacturing conditions. However, poor overall performance and low electrode utilization (much of the electrode material ends up being electrochemically inactive) are the main barriers implementing them in (micro)grid systems.

Here we characterize the surface reactions on NASICON-type phosphate anode material and rationalize their close associations with capacity fading upon slow cycling of aqueous sodium-ion batteries. The surface reactions result in the formation of an electrically insulating surface layer causing the failure of electrochemical performance and the precipitation of surface particles that blocks the pores thereby leading to poor electrode utilization. These findings provide insight into new possibilities of improving the electrochemical performance of aqueous sodium-ion batteries by the design of protective layers through surface modifications that prevent the formation of insulating surface layers and insoluble precipitates.
Jahn-Teller Distortion and Electrode Performance of P’2-Na2/3Mn0.9Me0.1O2 (Me = Mg, Ti, Co, Ni, Cu, and Zn)
Authors: Kumakura Shinichi , Tahara Yoshiyuki , Sato Syuhei , Kubota Kei , Komaba Shinichi
Published: February 2020

Mn based P2-type layered oxides, Na2/3Me
y
Mn1-y
O2 (Me=a variety of metals), have been widely studied as positive electrode materials for Na-ion batteries, especially consisting only of the abundant elements in the Earth’s crust, such as P2-Na2/3[Fe1/2Mn1/2]O2. [1] The end member, P2-type Na2/3MnO2 is known to have crystal polymorphism, P2- and P’2- Na2/3MnO2 with hexagonal and orthorhombic lattice, respectively. The orthorhombic system is stabilized by co-operative Jahn-Teller distortion (CJTD) derived from six-coordinated high spin MnIII (t2g
3-eg
1
). Very recently, our group reported that the single-phase samples of these polymorphs, P2-Na0.59Mn0.9O2 and P’2-Na0.64MnO2, possess different stoichiometry and demonstrate the superior electrochemical performance of distorted P’2 sample [2], though the distortion in insertion materials is generally considered to be disadvantageous for battery application. Therefore, quantitative understanding how CJTD affects electrochemical properties such as reversibility, kinetics of sodium diffusion, and long-cycle stability is of great importance to realize high capacity performance of MnIII based oxide materials for high energy density NIBs. In this study, we demonstrate the systematic synthesis of differently distorted P’2-Na2/3MnO2samples by partial replacement of Mn with different metal elements to correlate their electrochemical properties and lattice distortion.

Single phases of P’2-Na2/3Mn0.9Me0.1O2 (Me = Mg, Ti, Co, Ni, Cu, and Zn) are synthesized when we optimized facile solid-state reaction. The distortion calculated from lattice constant is highly correlated with average oxidation state of manganese varied by divalent metals (MgII, NiII, CuII, ZnII), trivalent metal (CoIII) and tetravalent metal (TiIV). Because of Jahn-Teller active CuII
(t2g
6-eg
3
), P’2-Na2/3Mn0.9Cu0.1O2 possesses anomalous distortion compared to other samples with divalent-metal dopants as shown in Figure 1a. All samples show high reversible capacity about 200 mAh g-1 and have smooth charge/discharge profiles. Fig. 1b compares charge/discharge curves of divalent-metal doped samples. The P’2-Na2/3Mn0.9Ni0.1O2 delivers the reversible capacity of 227 mAh g-1 and the Na2/3Mn0.9Cu0.1O2shows stable electrochemical cycling, 95% capacity retention after 25 cycles. In this presentation, we will further discuss the effect of metal-substitution and lattice distortion on electrochemical properties and demonstrate successful improvement of both cycle and rate performance by Cu doping.

References:

N. Yabuuchi, S. Komaba, et al., Nat. Mater., 11, 512 (2012).

S. Kumakura, Y. Tahara, K. Kubota, S. Komaba, et al., Angew. Chem. Int. Ed.
55, 12760 (2016).

Figure 1
Anode Free High Energy Density Sodium Batteries
Authors: Cohn Adam P , Pint Cary L.
Published: February 2020

Sodium-ion batteries (SIBs) have been pursued as a more cost-effective and more sustainable alternative to lithium-ion batteries (LIBs), but these advantages come at the expense of energy density. In this study, we demonstrate that the challenge of energy density for sodium chemistries can be overcome through an anode-free architecture enabled by the use of a nano-carbon nucleation layer formed on Al current collectors. The carbon nucleation layer lowers the overpotential for metal plating, supports uniform growth of sodium nuclei on the collector, and mitigates adverse effects of shorting or instability over extremely long cycling durations. Electrochemical studies demonstrate highly stable and efficient plating and stripping of sodium metal over a range of currents up to 4 mA/cm2, sodium loading up to 12 mAh/cm2, and with long-term durability exceeding 1,000 cycles at a current of 0.5 mA/cm2. Building upon this anode-free architecture, we demonstrate a full cell using a pre-sodiated pyrite cathode to achieve energy densities of ~400 Wh/kg based on total mass of electrode materials and sodium, far surpassing recent reports on SIBs and even the theoretical maximum for LIB technology (387 Wh/kg for LiCoO2/graphite cells) while still relying on naturally abundant raw materials and cost-effective aqueous processing.
Interfacial Chemistry at the Surface of Li-Metal Anodes
Authors: Balbuena Perla B , Camacho-Forero Luis Eduardo , Kamphaus Ethan , Bertolini Da Silva Oliveira Samuel , de la Llave Ezequiel
Published: February 2020

Efficient energy storage is essential not only for the success of renewable energies, but also for many of daily society needs including communications, electronics, and medical and biomedical applications, among others. Electrochemical cells are complex systems integrated by several materials and their corresponding interfaces whose physical-chemical behavior is dominated by highly coupled mass and electron transport and chemical and electrochemical reactions. During lithium ion battery operation for example, during charge, lithium ions move in the electrolyte towards the anode surrounded by coordination spheres that may include solvent, salts, and other species such as additives. Once the solvated ion (inserted in a usually multicomponent network) reaches the anode surface, many additional events will take place because of the sequential and sometimes almost simultaneous reduction of the cation and that of the various components of the coordination shell.

To characterize such complex environment, we analyze the Li ion coordination shell as a function of the distance to the electrode surface and electrode potential. We use density functional theory (DFT) and ab initio molecular dynamics (AIMD), to identify structural properties, as well as reactions and reaction mechanisms. Among the various “additional” species we consider the presence of long-chain polysulfides, that migrate in the electrolyte towards the Li metal anode in the Li-S chemistry. In this talk we will discuss physical, chemical, and electrochemical phenomena occurring at solid/electrolyte interfaces of Li-ion batteries and how the methods of first-principles computational analysis may be used to understand them and suggest strategies for practical solutions. In particular we will focus on the solid electrolyte interphase (SEI) occurring due to electrolyte reduction on or near Li anode surfaces and the role of the nature of the solvents, salts, and additives on the resultant SEI properties as well as on dendrite formation and battery performance.
Industrial Carbon-Coated Current Collectors Grades for Higher Energy and Power Density Lithium Ion Batteries
Authors: Busson Christophe , Lestriez Bernard , Crosnier Olivier , Blin Marie-Anne , Guichard Pierre
Published: February 2020

Electric mobility and renewable energy storage became very challenging and will continue growing up in interest on the next decades. Lithium-ion batteries are one of the most acclaimed devices to treat these problematics and constant developments on this technology aim to achieve higher specific energy density and specific power in order to fit numerous applications. Since the beginning of research on lithium ion energy storage devices, a large part of studies focus on the optimization of electrolytes, active materials and also, but more recently, on the electrode formulation. Although they are effective ways to improve these systems performances, they usually put aside the current collectors influence. However, several shortened lifetime, failures, or reduced performance can be ascribed to the metallic current collector. We can take as an example the electrode delamination [1], the metallic corrosion [2] or the electrical contact resistivity between the current collector and the electrode [3]. To avoid these problems, a conductive and protective coating of the metallic current collector (fig.1) can be added to obtain a better interface between the electrode and its substrate. In the present work, various types of carbon-coated aluminum current collectors for positive electrodes will be presented and compared to bare aluminum foils. Their characteristics such as physical properties, ageing on electrolyte, electrode affinity and electrical resistivity will be presented. The electrochemical performance will be assessed in full cells with a LiFePO4 – PVdF positive electrode, graphite negative electrode and carbonate-based electrolyte with LiPF6. Results of electrochemical impedance spectroscopy, C-rate capability and cycling experiments will be discussed. By reducing the carbon content of electrode, the bare aluminum shows a raising internal resistance by more than a factor two, an optimized coated current collector allows containing a smaller value. With a low carbon content in the electrode formulation, the capacity retention is about only 40% for bare aluminum system, and 60% for a coated current collector after 500 cycles in severe cycling conditions. These results show that an improvement of energy density and power capability are possible with an adapted coated current collector.

[1] S. Lee, E-S. Oh, J. Power Sources 244 (2013) 721-725.

[2] I. Doberdò, N. Löffler, N. Laszczynski, et

Al
.
,, J. Power Sources 248 (2014), 1000-1006.

[3] S. Wennig, U. Langklotz, G-M. Prinz, et Al., J. Appl. Electrochem 45 (2015), 1043-1055.

Figure 1
In-Situ Measurements of Volume Change and Constraint Forces of C-Si Pouch Cells during Cycling
Authors: Wen Hao , Karulkar Mohan , Drews Andy
Published: February 2020

Silicon has been targeted as an anode material that can deliver higher capacity for lithium ion batteries than current prevailing graphite. One strategy to minimize the detrimental effects of volume expansion during lithiation of silicon is to use a limited amount of silicon in combination with graphite. Even in these cases, however, cell volume expansion is a key concern when considering battery packaging for applications like electric vehicles, where cells are cycled over a wide state-of-charge window and packaged energy density is critical to delivering long range. The first step towards understanding the implications of expansion to cell design and packaging is to characterize the volume expansion of silicon-containing cells during use.

In the current work, in-situ volume and pressure responses of pouch cells were carefully measured with specially designed in-house fixtures (Figure 1). Volume expansion of pouch cells was measured by tracking the buoyancy force with a high precision balance, giving volume change precision to 1 micro liter with a long-term drift of < 10 microliter/day. Cell stack loading pressure was investigated by constraining cells between two fixed plates and a floating plate under a load cell. We found that the volume and pressure fixtures provided very similar patterns during pouch cell charging and discharging. Commercially available NMC/Graphite pouch cells showed symmetric and reversible P/V responses, while in-house cells with silicon-composite anodes showed an asymmetric response and long-term drift associated with continued SEI formation and gas generation. [1] L. Lu, X. Han, J. Li, J. Hua, M. Ouyang, J. Power Sources, (226) 2012, pp 272 - 288

Figure 1
Carbon Encapsulated Silicon Nanoparticles As Anodes for Lithium Ion Batteries
Authors: Livan Pelin , Öztürk Tayfur
Published: February 2020

Most recently, silicon anodes for lithium ion batteries have been extensively explored due to their large theoretical capacity, moderate operation potential, environmental friendliness and high abundance. However, poor capacity retention caused by the large volume change during intercalation process of lithium ions, its intrinsic low conductivity and the formation of insulating solid electrolyte interphase (SEI) films are limiting factors for applications of silicon anodes. The most common attempt is to combine the Si structure with a conducting carbonaceous layer, which possess excellent flexibility, high conductivity, light weight, electrochemical and thermal stability. In addition to the ability to accommodate the volume change and enhance electrical conductivity, encapsulation of Silicon nanoparticles in a protective and homogenous carbon coating prevent agglomeration and environmental oxidation. In this study, feasibility study of encapsulation process of Silicon nanoparticles was carried out with a arc discharge generator were the metal was made one at the electrode against graphite. Followed by this preliminary study, additional experiments were carried out with RF induction thermal plasma system where methane gas fed into the system in different feeding locations. The products were analyzed using different characterization techniques: XRD, SEM and HRTEM. Raman spectroscopy was used to analyze the quality of carbon shells. Efficient and scalable approaches were used to obtain carbon encapsulated Si nanostructures for use in lithium ion batteries. Also, utilization of comparative synthesis methods provide the direct observation of mechanism of encapsulation process and effects of the process parameters on the morphology and structure of encapsulates.

Figure 1
Forcespinning: An Alternative Method to Produce Metal Sulfides/Carbon Composite Nanofibers As Anode Materials for Lithium-Ion and Sodium-Ion Batteries
Authors: Alcoutlabi Mataz , Agubra Victor , Zuniga Luis , Valdez Alejandra
Published: February 2020

We present results on the Forcespinning (FS) of SnS2/SnO2/PAN and MoS2/PAN precursors for the mass production of SnS2/SnO2 /carbon and MoS2/C as anode materials for Lithium-ion and Sodium-ion batteries. The binary composite nanofiber electrodes of SnS2/SnO2/C and MoS2/C are produced using a scalable technique (FS) and subsequent thermal treatment (calcination). The composite nanofiber anodes were porous and flexible. The nanofiber preparation process involved the FS of SnS2/SnO2/PAN and MoS2/PAN precursors into nanofibers and subsequent stabilization in air at 280oC and calcination at 800oC under an inert atmosphere. The flexible composite nanofibers were directly used as working electrode in lithium-ion and sodium-ion batteries without a current collector, conducting additives, or binder. The SnS2/C and SnS2/SnO2/C electrodes delivered a specific capacity of 556 mAhg-1 and 965 mAhg-1 respectively during the first sodiation cycle. This initial high capacity is attributed to the irreversible formation of a stable SEI layer and to the porous structure of the Forcespun composite nanofibers. In the subsequent cycles, the SnS2/C electrode exhibited a much stable cycling performance compared to SnS2/SnO2/C i.e. 145 mAhg-1 was maintained after 50 cycles. The MoS2/C composite nanofiber electrodes delivered a good electrochemical performance and Coulombic efficiency when used for Lithium-ion batteries. This study provides a novel and feasible pathway for designing and developing promising anodes and cathodes for high-performance lithium ion and sodium-ion batteries.