bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Electrochemical Charging on Fracture Toughness and Elastoplastic Properties of LiCoO2
Authors: Swallow Jessica G. , Woodford William H , McGrogan Frank P , Ferralis Nicola , Chiang Yet-Ming , Van Vliet Krysytn J.
Published: February 2020

Capacity fade and impedance growth of lithium ion battery (LIB) electrodes have been correlated with mechanical degradation of active particles through extended cycling.  The design of fracture-resistant electrodes requires understanding of material mechanical properties such as elastic modulus E, hardness H, and fracture toughness K
Ic over the entire range of compositions through which the active materials are cycled.  In this work, we measured E, H, and K
Ic of the prototypical layered material LiXCoO2 using instrumented nanoindentation, varying the composition, X, through varying durations of galvanostatic charging.  We found that within a single charge cycle, E and H decreased by up to 60%, while K
Ic decreased by up to 70% compared to the fully-lithiated state. X-ray diffraction, Raman spectroscopy, and optical and electron microscopy demonstrated that the drop in mechanical properties was correlated with extensive grain boundary fracture and attributable to Li depletion at the sample surfaces.  Such differences in mechanical properties of Li-storage materials can impact the critical length scales (either grain size or particle size) that mark the boundary between fracture-resistant and fracture-prone electrode designs.  This work demonstrates that when fracture toughness is used in battery design, it cannot be assumed to be constant over the course of charge cycling. This evidence of electrochemical-history-dependent fracture toughness is particularly important to the design of Li-storage compounds that undergo significant chemical expansion or phase changes during electrochemical cycling.
Aerosol Spray Deposition of Carbon Nanotube Enhanced LiFePO4 Batteries
Authors: Tennyson Wesley Daniel , Duong Nhung N , Stevens Adam H , Resasco Daniel E
Published: February 2020

Batteries technologies with high power and high energy density seem to be inevitable exhibit poor battery life. Nevertheless, the need to solve our energy and transportation problems demands that we make materials that can both deliver high current densities and do it reliably over thousands of cycles. A failure mechanism within the composite of intercalation cathodes is the loss of electrode contact as the materials swell and crack during Lithiation and de-Lithiation. A well dispersed and stabilized conductive network of carbon nanotubes should alleviate this failure mechanism. Producing a well dispersed and well connected network of CNTs cannot be done with ball milling, the traditional battery mixing method, as the CNTs tend to be broken apart instead of dispersed. In this work we demonstrate an ultrasonication and aerosol deposition technique of CNTs, PVdF, and Lithium Iron Phosphate (LFP) that produces batteries that exhibit little capacity fade. Additionally, the inactive material content (10%) is drastically reduced compared to batteries made with carbon black (25%). Microanalysis demonstrates that the optimized aerosol method can produce composites with well dispersed and open networks of CNTs more effectively than slurry methods.
Inhibition of Al/Cu Contact Corrosion in Lithium Ion Batteries
Authors: El Mofid Wassima , Ivanov Svetlozar , Bund Andreas , Rentenberger Stephan , Goers Dietrich
Published: February 2020

Nowadays, the safety of lithium ion batteries (LIBs) has attracted considerable attention. Therefore, battery components have been studied rigorously in a way to reduce safety problems such as explosion and fire accidents [1]. A key component in LIBs is the current collector which ensures electronic conduction between the electrode materials and the external circuit. Metallic Al which is widely used as the current collector material for the positive electrode in LIBs [2,3] might be subjected to contact corrosion, when connected to Cu, during the charge and discharge cycles. Such phenomena can shorten the lifetime and compromise the safety of LIBs.

This paper will discuss the corrosion behavior of various coatings on Al in contact with metallic Cu. The coatings Ni, Cu and NHP (Nickel High Phosphorus with about 10%P) were studied as corrosion protection coatings for Al current collector.

The anodic behavior of the three coatings on aluminum substrates in an organic carbonate based electrolyte were investigated by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscopy (SEM). CV data showed that already after the second cycle Cu and NHP exhibited very low current densities and good passivation behavior. Results analysis in Tafel coordinates also demonstrated better corrosion behavior for Cu and NHP samples expressed by a shift of the corrosion potentials to more anodic values. At the same time their corrosion rate values are lower.

EIS data showed no considerable variation with the polarization potential especially in the high frequency range. Moreover, in the Nyquist representation the EIS data take approximately the shape of a straight line, suggesting that the charge transfer resistance Rct is large and no corrosion takes place in the potential region [3.6V-4.2V].

References

[1] B. Scrosati, J. Garche, J. Power Sources 195 (2010) 2419.

[2] C. Iwakura, Y. Fukumoto, H. Inoue, S. Ohashi, S. Kobayashi, H. Tada, M. Abe, J. Power Sources 68 (1997) 301.

[3] A.H. Whitehead, M. Schreiber, J. Electrochem. Soc. 152 (11) (2005) A2105.
Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds
Authors: Kinaci Alper , Yildirim Handan , Greeley Jeff , Chan Maria K. Y.
Published: February 2020

In rechargeable batteries, electrolytes are often unstable under operating potentials which results in the formation of a mixture of organic and inorganic compounds on the electrodes. This solid electrolyte interphase (SEI) has profound effects on battery performance. Thus, characterization of the SEI compounds in terms of ionic and electronic transport is essential for the understanding of the limitations in charge-discharge rates, overpotential, electrode passivation, metal plating etc. LiF and NaF are two of the common SEI compounds primarily formed when electrolytes contain fluorinated salts in Li- and Na-ion batteries. LiOH on the other hand, results from water content in the electrolyte. These materials have wide band gaps that favor the insulation of electrode surface by impeding further reduction of electrolyte. However, the ionic transport and the mediating defects in these compounds are still in question. In this study, we conducted density functional theory calculations to identify the defect formation energies and concentrations in a range of relevant Li and Na chemical potentials. We considered several possible defect sites at different charge states. The close packing of the LiF and NaF makes it energetically unfavorable for interstitials to be present in considerable quantities. However this is not the case for LiOH. Accordingly, vacancies of the constituent elements are found to be predominant defects in fluorides. Diffusion of Li and Na is also evaluated by employing nudged-elastic band (NEB) method in defected structures. The activated states and the diffusion barriers of possible transport routes will be presented.
Innovative Sulfur-Carbon Nanotube Cathodes for High-Performance Li/S Batteries
Authors: Yan Jianhua , Liu Xingbo , Li Bingyun
Published: February 2020

Li/S batteries suffer from major problems including low active material utilization, poor cycling performance and low Coulombic efficiency due to high solubility of intermediate polysulfides and low conductivity of sulfur. Here, wereport modified carbon nanotubes (MCNT)-S comprising the key features of elemental sulfur (S8) and sulfurized carbon (SC) when used as cathode materials. The use of a mixed solvent of MCNT in hydrogen peroxide and sulfur in carbon disulfide followed by 300°C heat treatment in vacuum oven leads to extremely uniform and dense sulfur layers on CNT surfaces via physical and chemical deposition, and enables the fabrication of remarkably improved Li/S cathodes with a reversible capacity of 1180 mAhg-1 without obvious capacity decay over 300 cycles at 0.25 C, and 67.5% of capacity retention from 1182 to 799 mAhg-1 over 600 cycles at 0.75 C with an average Coulombic efficiency of 95.5%. The results provide important progress towards the understanding of the role of MCNT on the realization of high efficiency and long cycle performances for Li/S batteries.
Silicon-Graphite Development: Robust, Practical, and Scalable High Performance Electrodes
Authors: Trask Stephen E , Polzin Bryant J , Kubal Joseph , Lu Wenquan , Jansen Andrew N.
Published: February 2020

Lithium-ion batteries in their current state of technology are not able to satisfy the transportation requirements set by the U.S. Department of Energy (DOE) for Hybrid Electric Vehicles, Plug-in Hybrid Electric Vehicles, and Electric Vehicles for gravimetric and volumetric energy capabilities. One approach to meet DOE’s transportation goals is to increase the capacity of the anode using silicon. Silicon has been recognized for several years as the most likely next generation high energy anode material. However, the silicon drop-in replacement of graphite is not as straight forward as it would seem.

Argonne National Laboratory has taken on the task of developing a silicon-graphite blend electrode to advance the lithium-ion battery technology and provide high quality electrodes to the battery community for further electrolyte development. Fabricating a robust, practical, and scalable high performance silicon-graphite electrode, with an emphasis on developing an electrode with >3 mAh/cm2, has required efforts to explore various sources of silicon powder, silicon particle sizes, graphite types, binder types, electrode compositions, compatible solvents for slurries, effective slurry mixing, and electrode coating conditions. The approach involved testing silicon-graphite exploratory slurries on the CAMP (Cell Analysis, Modeling, and Prototyping) Facility pilot-scale coating equipment to address processing issues on the coater and verify the scalability of developments.

The result of this work led to a silicon-graphite electrode containing 15 wt.% nano-silicon, 73 wt.% graphite, 2 wt.% carbon black, and 10 wt.% Li-PAA (lithiated poly acrylic acid) binder. The slurry has the capability of coating at least a 3.7 mAh/cm2electrode and shows much improved robustness, practicality, scalability, and reproducibility (Fig.1). Having this standard electrode enables diagnostic work, modeling, and electrolyte composition work. The silicon-graphite electrode is available in the CAMP Facility Electrode Library for the battery research community. The major barriers encountered and breakthroughs in the silicon-graphite electrode fabrication leading to the improved electrode will be discussed in this presentation.

Acknowledgement:

Support from Peter Faguy and David Howell of the U.S. Department of Energy’s Office of Vehicle Technologies Program is gratefully acknowledged.  This work was performed under the auspices of the US Department of Energy, Office of Vehicle Technologies, under Contract no. DE-AC02-06CH11357.

Figure 1
Impact of Silicon Expansion upon Lithiation on Electrode and Cell Thickness
Authors: Jansen Andrew N. , Trask Stephen E , Polzin Bryant J
Published: February 2020

The constant demand for more energy in smaller volumes requires the need for high energy density cathodes and anodes. While there exists a portfolio of available cathode materials with increasing incremental improvements in energy, the choices on the anode side of the cell have been limited to graphite and hard carbon. In recent years, attention has been directed to improving the graphite energy density by adding silicon. However, the volume expansion of a silicon particle can approach 400% upon full lithiation. This large expansion and contraction of the silicon particle during electrochemical cycling not only has a negative influence on the robustness of the solid electrolyte interface (SEI) layer, but also negatively impacts the dimensional tolerance of the electrode, cell, and battery.  

In this work, the variation of the electrodes and cell thickness is measured for a baseline graphite and several silicon-graphite/graphene electrode systems. These values were determined before cycling, after formation, and at various states of charge by measuring the entire cell thickness change and the electrodes themselves after disassembly. For this study, xx3450 (format size) single-sided single-layered pouch cells were used with ~20 mAh capacity, and 1.2 M LiPF6 in EC:EMC (3:7 wt.%) + 10 wt.% FEC was used as the electrolyte. These cells were made and tested in Argonne’s Cell Analysis, Modeling, and Prototyping (CAMP) Facility.

Figure 1 is a summary of the percent change in thickness for the anode only relative to the initial dry electrode for the baseline graphite anode and three classes of silicon-based anodes still in development. The silicon-based anodes in general have a higher percent rise in thickness than graphite alone, but with proper particle composition and morphology the impact on electrode thickness can be controlled to an acceptable level. In these cells, the cathode (and separator) changes were relatively insignificant.

The impact of anode expansion on the total cell thickness was estimated for various anode-cathode pairings. With proper electrode design, it was found that the variation in cell thickness during charge and discharge could be held within 10% for the three classes of silicon-based anodes studied in this work, provided the silicon content was the minor constituent. While accounting for the thickness changes in anode systems is an important feature to monitor when using silicon-based materials, more work is still needed to enhance their cycle life.

Support from David Howell and Peter Faguy of the U.S. Department of Energy’s Office of Vehicle Technologies is gratefully acknowledged. This work was performed under the auspices of the US Department of Energy, Office of Vehicle Technologies, Hybrid and Electric Systems, under Contract No. DE-AC02-06CH11357

Figure 1
Li1.14Mn0.53Ni0.28Co0.19Oy layered-Layered Spinel Material Prepared Using Taylor Vortex Reactor
Authors: Kahvecioglu Feridun Ozgenur , Shin Youngho , Krumdick Gregory
Published: February 2020

In this work, precursor for Li1.14Mn0.53Ni0.28Co0.19Oylayered-layered spinel cathode material was synthesized by carbonate co-precipitation method using a Taylor Vortex reactor. In a similar fashion, we also utilize a 20L continuous stirred tank reactor (CSTR) to produce and compare the cathode materials with same composition.

Recently, layered-layered spinel structures are explored to mitigate the voltage fade issue to some extent. Even though these materials deliver lower capacities than the Li- and Mn- rich (LMR-NMC) materials, they have the key feature of “spinel induced” structures which make the voltage fade relatively less compared to LMR-NMC materials.

Here, by adopting Taylor Vortex reactor, we demonstrate that the usage of Taylor Vortex Flow shows good advantages to produce highly crystalline, spherical and dense cathode precursors in a relatively short residence time compared to CSTR.

The particle size and distribution of the synthesized cathode powders are analyzed using particle size analyzer (PSA) and are confirmed with scanning electron microscopy (SEM). The composition and the phase determination of the cathode materials are characterized by inductively coupled plasma mass spectroscopy (ICP-MS) and X-ray diffraction (XRD). These cathode materials were electrochemically tested using Voltage Fade protocol of Argonne National Laboratory.
Lithium Sulfur Battery: Current Status and Future Prospects
Authors: Hara Toru , Kurmanbayeva Indira , Mentbayeva Almagul , Bakenov Zhumabay
Published: February 2020

Lithium sulfur battery is a promising candidate for the next generation rechargeable battery since the negative electrode, lithium, and the cathode, sulfur, have the highest theoretical capacities of 3862 and of 1672 mAh/g, respectively, among any other active materials, e.g., graphite (372 mAh/g) or LiCoO2 (274 mAh/g, only about 50% is practically available). However, there are several challenging issues in order to realize the use of this type of next generation battery. First, the lithium metal anode has an intrinsic safety issue, dendrite growth that can result in internal short circuit failure. Second, the sulfur cathode is a very insulating material; therefore, sulfur-based cathodes need a large amount of conducting additives, resulting in the decrease in the practically available gravimetric capacity per the unit mass of cathode composite. Third, lithium polysulfides, reduced (discharged) forms of sulfur, dissolve into an electrolyte solution, resulting in capacity fading. For realistic battery applications, these issues from both the anode and the cathode need to be solved or mitigated. To this end, we integrate three practically possible solutions: (1) manufacture-friendly pre-lithiation of anode or cathode materials, (2) practically optimal choice of conducting agent and of the method for sulfur-conductive-agent integration, and (3) stabilization of discharged forms of the cathode. In addition, we are tackling with a well-known issue among lithium sulfur battery researchers, low mass-loading of sulfur: sulfur-based cathode, 2 mg/cm2; LiCoO2-based cathode, 20 mg/cm2, graphite-based anode, 10 mg/cm2. In this presentation, the current status of our research and future prospects will be introduced.

Figure 1
Investigations of Lithium-Sulfur Batteries at Low and High Temperatures
Authors: Cañas Natalia Andrea , Zhao Sijie , Wagner Norbert , Friedrich Kaspar Andreas
Published: February 2020

The research of lithium-sulfur (Li-S) batteries keeps growing motivated by its high theoretical energy density (around 2600 Wh kg-1) and the continuous improvement on the cycling stability, like it has been gained in the last five years [1,2]. In situ and ex situ techniques have been already developed to get a deeper understanding on reaction mechanisms and degradation processes [1-5]. However, only few studies investigated the behavior at temperatures below and above ambient [6,7].

In this work, Li-S batteries were investigated in a temperature range between -15 °C and 75 °C. The cathode consisted of a simple carbon/sulfur composite and lithium foil was used as anode. Two electrolytes were investigated: 1 M Lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) in DOL:DME (1:1, v:v) with and without LiNO3. Electrochemical impedance spectroscopy was chosen as principal characterization technique to evaluate the influence of the temperature on the electrochemical and degradation processes. The resistance of electrolyte, charge transfer resistance in the electrodes, as well as the dissolution and precipitation of the end products (sulfur and lithium sulfide) were analyzed by modelling the experimental results with an equivalent electric circuit. Furthermore, the function of the already known electrolyte co-salt LiNO3 to avoid the shuttle mechanism was evaluated in a wide temperature range. The results show that the “protective” effect of LiNO3 is negatively influenced by extreme temperatures. Moreover, morphology and structural changes in the sulfur/carbon composite cathode were analyzed using ex situ scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively.

1. A. Manthiram, Y. Fu , S.-H. Chung , C. Zu , Y.-S. Su, Chem. Rev., 2014, Article ASAP, DOI: 10.1021/cr500062v

2. M.-K. Song, E. J. Cairns, and Y. Zhang, Nanoscale, 2013, 5, 2186–204.

3. N. A. Cañas, K. Hirose, B. Pascucci, N. Wagner, K. A. Friedrich, and R. Hiesgen, Electrochim. Acta, 2013, 97, 42–51.

4. N. A. Cañas, S. Wolf, N. Wagner, and K. A. Friedrich, J. Power Sources, 2013, 226, 313–319.

5. N. A. Cañas, D. N. Fronczek, N. Wagner, A. Latz, and K. A. Friedrich, J. Phys. Chem. C, 2014, 118, 12106–12114.

6. Y. V. Mikhaylik and J. R. Akridge, J. Electrochem. Soc., 2003, 150, A306.

7. X. He, W. Pu, J. Ren, L. Wang, J. Wang, C. Jiang, and C. Wan, Ionics, 2007, 14, 335–337.

Figure 1
N-Doping Effect for Polysulfide Reservoir within Mesoscale Electrodes for Practical Application of Lithium Sulfur Batteries
Authors: Chen Junzheng , Wu Dangxin , Walter Eric , Engelhard Mark H , Bhattacharya Priyanka , Pan Huilin , Shao Yuyan , Gao Fei , Xiao Jie , Liu Jun
Published: February 2020

Lithium sulfur batteries have become one of the most promising energy storage technologies, potentially meeting the needs for vehicle electrification and stationary applications, because of its lower costs, environmental friendly property and much higher energy density (cathode theoretical energy: 3500 Wh/kg, or 2800 Wh/L) than that of state-of-art Li-ion batteries. However, many challenges exist for the broad deployment of Li/S system. The main challenge is the low Columbic efficiency and fast capacity decay due to the shuttle reactions caused by the soluble intermediate polysulfide

Nitrogen-doped porous carbon (NPC) and multi-wall carbon nanotube (MWCNT) have been frequently studied to immobilize sulfur in lithium-sulfur (Li-S) batteries. However, neither NPC nor MWCNT itself can effectively confine the soluble polysufides if cathode thickness e.g. sulfur loading is increased. In this work, NPC was combined with MWCNT to construct an integrated host structure to immobilize sulfur at a relevant scale. The function of doped nitrogen atoms was revisited and found to effectively attract sulfur radicals generated during the electrochemical process. The addition of MWCNT facilitated the uniform coating of sulfur nanocomposites to a practically usable thickness and homogenized the distribution of sulfur particles in the pristine electrodes, while NPC provided sufficient pore volume to trap dissolved species. More importantly, the wetting issue, the critical challenge for thick sulfur cathodes, is also mitigated after the adoption of MWCNT, leading to a high areal capacity of ca. 2.5 mAh/cm2 with capacity retention of 81.6% over 100 cycles. This work provides clues on the fundamental mechanism of N-doping and the strategies to practically develop nano-structured materials for battery applications.

Acknowledgment

This work was supported by the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The EPR, XPS, and SEM analyses were performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Department of Energy’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL).
SEI-Film-Suppression Additive for Enhancing Compatibility and Electrochemical Stability of Graphite Anode in PC-Based Electrolytes
Authors: Xiang Hongfa , Yan Pengfei , Bhattacharya Priyanka , Bowden Mark E , Cao Ruiguo , Qian Jiangfeng , Polzin Bryant J , Wang Chongmin , Zhang Ji-Guang , Xu Wu
Published: February 2020

Lithium-ion batteries (LIBs) are one of the most promising power sources for electric vehicles because of their high energy density and long lifetime. Graphite is widely used as anode electrode material in the state-of-the-art LIBs. However, a graphite anode is usually only compatible with an ethylene carbonate (EC)-based electrolyte. When contacting with a propylene carbonate (PC)-based electrolyte, which is advantageous over the EC-based one for its wider temperature range and higher low-temperature conductivity, the graphite anode may suffer from substantial exfoliation problem during the initial lithium intercalation step. Consequently, a PC-based electrolyte cannot be used in LIBs with graphite as the anode unless some solid electrolyte interphase (SEI) film-formation additives are introduced into the electrolytes. Usually this type of additives is reduced predominantly on the graphite electrode surface before PC is intercalated and reduced. These additives mainly contain some functional groups such as vinylene or cyclic unsaturated compounds. For example, vinylene carbonate (VC) and fluoroethylene carbonate (FEC) have been widely studied and used as additives for PC-based electrolytes. They play an important role in the protection of the structure of the graphitic anode from destruction by PC, but they also have some shortcomings. Usually these additives result in a thick SEI protective layer, which could significantly reduce the rate capability and limit low-temperature performance and cycling stability at elevated temperatures because of its additional impedance and poor thermal stability.

Recently, we developed a novel electrolyte additive that can suppress the PC reductive decomposition on the graphite anode without a thick and resistant SEI film. The additive may provide a novel protective mechanism for the graphite anode in the PC-containing electrolytes without or with suppressed SEI film formation. The SEI-film-suppression additive can not only significantly improve the compatibility between graphite anode and PC-containing electrolyte, but also exhibit superior rate capability and excellent cycling stability at elevated temperatures.We believe that this new electrolyte additive can be applied to LIBs and other electrochemical systems using PC-containing electrolytes and graphite anodes. The details of the results will be reported.

  

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technology of the U.S. Department of Energy (DOE). The electron microscopy and XRD measurements were performed at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL.
(Invited) New Electrolyte Solvents and Additives Designed for Li Ion and Beyond Chemistries
Authors: Xu Kang , Zhang Zhengcheng , Abraham Daniel P , Amine Khalil , Cresce Arthur v. , Russell Selena M. , Borodin Oleg , Wang Chunsheng
Published: February 2020

Ever since the birth of Li ion chemistry, carbonate esters have been the main solvents used as the skeleton composition of the electrolytes. This class of polar organic compounds, ethylene carbonate in particular, brings both their merits of supporting reversible intercalation of Li+ at electrodes of potential differences as wide as 4.2 V, and their intrinsic limits of narrow temperature range, chemical reactivity toward conducting salts, and inflammability. Numerous efforts were made during the past decades in an attempt to replace these carbonate, either partially or entirely, but little change has occurred as the result.

The emergence of new chemistries such as the high voltage (>4.5 V) cathode intercalation materials and the beyond-Li-ion concepts −− most of which resort to conversion-reaction concepts to maximize the specific capacities −− presents unprecedented challenges to these carbonate esters that have been widely used by Li-ion industry, and activities resumed in seeking new alternatives. This presentation will summarize our recent efforts of designing, synthesizing and characterizing such new electrolyte solvents in both high voltage and Li-ion as well as beyond-Li-ion chemistries.
Galactomannan-Bound Battery Electrodes for High-Performance Applications
Authors: Dufficy Martin K , Khan Saad A , Fedkiw Peter S
Published: February 2020

Lithium-ion batteries are ubiquitous energy storage devices, yet expanding market needs require higher energy and power densities than presently available. Inexpensive materials with low-processing costs stimulate the exploration of novel battery materials. One possible solution to meet charge capacity demands is through the incorporation of silicon in anode materials. However, volume expansions during lithiation leads to fractured electrodes and binders, which leads to electronic isolation. Binding agents are a critical component in a battery and may also be used to enhance electrode performance. Herein, we report the use of galactomannans—an inexpensive, environmentally friendly, biorenewable polymer—as a novel binder for Si electrodes. Silicon-containing electrodes with as low as 5 wt.% binder exhibit large reversible capacities with > 90% charge retention after 100 cycles without use of electrolyte additives. Increased capacities allow for greater energy densities while lower binder content allows for fast Li-extraction for high-power applications (Figures 1a, b). The observed performance enhancement may be attributed to polymer-particle interactions between the hydroxyl groups of galactomannans and native-oxide layer of Si. The interactions, coupled with the inherent mechanical integrity of galactomannan thin films, allow for minimal electrode cracking and delamination upon lithiation. The undamaged electrode microstructure during large volume expansions (Figure 1c) allows for columbic efficiencies > 99% to be observed. Galactomannans also experience ample polymer swelling in common electrolyte solvents, which leads to rapid Li transport and lower resistivities than other biopolymer-bound electrodes. Galactomannan binders may thus provide a critical step forward in next-generation lithium-ion batteries.

Figure 1. (a) Charge/discharge profiles of guar gum-bound Si electrodes and (b) Li-extraction capacities using guar gum and locust bean gum as binders. Electrodes were lithiated at 0.05-C and delithiated at the specified C-rate. (c) The scanning electron microscope image shows the undamaged porous electrode structure of galactomannan-bound Si nanoparticles after 50 charge/discharge cycles of deep lithiation at 1-C.

Figure 1
Optimization of the Thermal Treatment of Electrospun Poly(acrylonitrile) for Flexible, Binderless, and Collectorless Lithium-Ion Carbon Nanofibers Anode
Authors: Beach Jeremy , Moore Robert B
Published: February 2020

The processing of carbon nanofibers prepared by electrospinning poly(acrylonitrile) and subsequent thermal treatment has been optimized for use as a binderless, flexible, and collectorless anode for lithium ion batteries.  Previous literature has failed to report, and in some instances account for, all aspects of processing as they relate to specific capacity in a comprehensive and systematic study.  Solutions of 12 wt% poly(acrylonitrile) in DMF were used throughout and were electrospun and thermally treated using various approaches.  The highest specific capacity obtained after 10 cycles at a current of 100 mA/g was greater than 550 mAh/g and exhibited Coulombic efficiencies of < 98% after the first cycle.  This specific capacity is <30% higher than previously reported anodes cycled at half of the reported current (50 mA/g) and almost 200 mAh/g higher than the theoretical capacity of pure graphite (372 mAh/g).  Flexible carbon nanofibers prepared by this scalable method have been shown to be a viable binderless and collectorless lithium ion anode material.  Applying these concepts to carbon nano-composite anodes previously reported in literature would further enhance their energy and power densities.
Redox-Active Functionalized Graphene Nanoribbons As Electrode Material for Li-Ion Batteries
Authors: Pirnat Klemen , Bitenc Jan , Jerman Ivan , Dominko Robert , Genorio Bostjan
Published: February 2020

Current Li-ion systems still require substantial optimization in terms of realizing a more favorable price-to-performance ratio, especially in the renewable energy storage sector. To achieve this, several new materials and approaches are currently being tested and developed and, in particular, great promises and expectations lie in the graphene-based materials. Graphene is a stable 2D honeycomb-structured carbon material with extraordinary mechanical, optical, thermal and electrical properties.1 On the other hand redox-active organic materials offer high theoretical capacities; however, most organic materials show drastic capacity fading during cycling, mainly caused by the dissolution of the active materials in organic electrolytes. In this work, we combined extraordinary properties of graphene with high capacity of organic compounds to get electrochemically stable composite material.  Graphene nanoribbons (GNRs) were grafted with electroactive molecules, where functionalized GNRs serve as a current collector, binder, and active material at the same time. GNRs were prepared by unzipping commercially available multi-walled carbon nanotubes with a Na/K alloy and in-situ functionalized with different hydroquinone derivatives. All synthesized materials were electrochemically characterized in Li-ion battery cells. The physical characteristics of the synthesized materials were determined by using evolved-gas analysis, Raman spectroscopy, and scanning electron microscopy. These analyses show the successful functionalization of GNRs and improved electrochemical performance compared to non-functionalized GNRs.2

(1) Rao, C.; Sood, A. Graphene: Synthesis, Properties, and Phenomena; Rao, C. N. R.; Sood, A. K., Eds.; 1st ed.; Wiley-VCH Verlag GmbH & Co. KGaA: Weinheim, 2013; p. 400.

(2) Pirnat, K.; Bitenc, J.; Jerman, I.; Dominko, R.; Genorio, B. Redox-Active Functionalized Graphene Nanoribbons as Electrode Material for Li-Ion Batteries. ChemElectroChem
2014, n/a–n/a.

Figure 1
Insight for Formation of Oxygen Deficiency in Spinel-Type LiNi0.5Mn1.5O4-δ
Using Ab Initio DFT Calculations
Authors: Shiiba Hiromasa , Zettsu Nobuyuki , Nakayama Masanobu , Oishi Shuji , Teshima Katsuya
Published: February 2020

Spinel-type LiNi0.5Mn1.5O4 (LNMO) have attracted attention as cathode materials for lithium-ion batteries due to its high-voltage at ~ 4.7 V vs. Li+/Li. LNMO is considered to belong to two different crystal structures such that Ni/Mn ordered P4332 and disordered Fd-3m. Relationship between crystal structures and their electrochemical performances has been experimentally- and computationally- investigated, showing that disordered Fd-3m structure contains oxygen deficiency with reduction of Mn from Mn4+ to Mn3+. Although the presence of Mn3+ improve electronic conductivity, Jahn-Teller distortion and dissolution of Mn occurs. Phase transition from disordered Fd-3m to ordered P4332 occurs with diminish oxygen deficiency by annealing in oxygen atmosphere at 700 ̊C. Understanding the formation mechanism of the oxygen deficiency would be helpful to synthesis aimed crystal structure. However, computational studies with oxygen deficient model are limited so far. In this study, we evaluate the defect formation energies in oxygen deficient LNMO.

The Vienna ab initio simulation package (VASP) was utilized with the generalized gradient approximation (GGA-PBEsol) + U and projector-augmented wave (PAW) methods. For the GGA + U calculations, the U values for the d-orbitals of Ni and Mn were set to 6.0 eV and 3.9 eV following relevant previous reports. An energy cutoff of 500 eV and a k-point mesh were chosen such that the product of the number of k-points and the number of atoms in the unit cell was greater than 1000.

In the case of disordered  Fd-3m structure, we used ‘uniform’ Ni/Mn distribution computationally reported by Lee et al., that is, the highest degree of local cation arrangements within random cation ordering. Coulombic energy was calculated for different 524 structures by Ewald method, the most stable Ni/Mn arrangement was consistent with ‘uniform’ distribution as mentioned above.

The calculated lowest oxygen vacancy formation energies in P4332 and Fd-3m show 3.69 eV and 3.38 eV, respectively. Note that vacancy formation energy almost no difference in P4332 among different oxygen vacancy concentrations, whereas, in Fd-3m, vacancy formation energy decreased with increasing oxygen vacancy concentrations. This fact strongly suggests that Fd-3m structure promotes oxygen deficiency. In addition, not only oxygen vacancies type defect but also metal-excess type defect can be present as oxygen defect models. Formation energies for the system contains excess metals in P4332 and Fd-3m lattice show 2.98 eV and 2.58 eV, respectively. Formation energy for metal excess type in Fd-3m became 0.40 eV smaller than that in P4332, in agreement with experimental results that only Fd-3m contains oxygen defects. In addition, these values are lower than oxygen vacancy formation energies. These all finding indicates that metal-excess type oxygen deficiency can be more favorable than oxygen vacancy type oxygen deficiency for LNMO.
Interfacial Reactivity of a High Capacity Manganese Rich (HCMRTM) Li-Ion Positive Electrode
Authors: Terborg Lydia , Park Yirang , Venkatachalam Subramanian , Hernandez Pedro , Kostecki Robert
Published: February 2020

High capacity manganese rich (HCMR™) materials are promising candidates for commercial Li-ion battery positive electrodes for applications in electric and plug-in hybrid electric vehicles.1 These oxides, also denoted as xLiMO2 - (1-x)LiMnO3 (M = Co, Mn, Ni), deliver a high discharge capacity (>240 mAh/g) at operating voltages exceeding 3.5 V vs. Li/Li+.2 However, these materials have significant limitations and suffer from high first cycle irreversible capacity loss, impedance rise and voltage fade during cycling.2-4 Extensive studies of HCMR™ electrodes indicate a structural modification/ rearrangement as one of the major reasons for the electrode/material degradation. In this work, the surface and interfacial phenomena of HCMR™ electrodes were investigated using in situ and ex situ spectroscopic techniques as a function of electrode potential and charge/discharge cycling.

HCMR™ materials surface structural changes were investigated during electrochemical cycling by confocal Raman microscopy in a custom-designed spectro-electrochemical cell. A carbon- and binder-free cathode was prepared by pressing the active material onto Al foil, which is then loaded into the spectro-electrochemical cell. Figure 1 shows Raman spectra collected during a first charge-discharge cycle. Surface structural changes due to the delithiation of the HCMR™ material are observed by the change in position of the Raman peaks during cycling.

While the oxidation of Ni2+ to Ni4+ appears to be a fully reversible process, other surface structural changes manifest themselves during the prolonged cycling (Figure 2). A shift of the major peak Mn-O band from 595 cm-1 to higher frequency, as well as an increase in intensity for another Mn-O mode at 650 cm-1 was observed.

Shifting from the Raman spectra indicates significant structural deviation of the HCMR™ material during cycling. The correlation of the structural changes with the observed interfacial phenomena will be discussed in regards to their influence on the electrode and cell electrochemical performance and lifetime.

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, under the Applied Battery Research for Transportation (ABR) Program and Award Number DE-EE0006443.

 

References

1. M. M. Thackeray, S. H. Kang, C. S. Johnson, J. T. Vaughey, R. Benedek and S. A. Hackney, J Mater Chem, 17, 3112 (2007).

2. Y. Li, M. Bettge, B. Polzin, Y. Zhu, M. Balasubramanian and D. P. Abraham, J. Electrochem. Soc., 160, A3006 (2013).

3. K. J. Carroll, D. Qian, C. Fell, S. Calvin, G. M. Veith, M. F. Chi, L. Baggetto and Y. S. Meng, Phys Chem Chem Phys, 15, 11128 (2013).

4. D. Mohanty, A. S. Sefat, S. Kalnaus, J. L. Li, R. A. Meisner, E. A. Payzant, D. P. Abraham, D. L. Wood and C. Daniel, J Mater Chem A, 1, 6249 (2013).

Figure 1
Mechanistic Insights into Rechargeability and Capacity Limitations in Nonaqueous Li-O2 Batteries
Authors: McCloskey Bryan D
Published: February 2020

Li-air batteries have received significant attention as a potential high specific energy alternative to current state-of-the-art rechargeable Li-ion batteries.1-3 However, numerous scientific challenges remain unsolved in the pursuit of attaining a battery with high capacity and modest Coulombic efficiency.  This presentation will highlight efforts to improve Li-air battery cyclability and capacity through studies that elucidate the mechanism of Li2O2 electrochemical formation and oxidation at the positive electrode.  Results will be presented confirming that Li-O2 battery capacity is limited by Li2O2-induced cathode electronic insulation and rechargeability is limited by electrolyte and electrode instabilities in the presence of Li2O2.4-5 Strategies to circumvent both of these challenges will be discussed.6

(1)  Bruce, P. G.; Hardwick, L. J.; Abraham, K. M. Lithium-air and lithium-sulfur batteries. MRS Bulletin
2011,
36, 506-512.

(2)  Girishkumar, G.; McCloskey, B.; Luntz, A. C.; Swanson, S.; Wilcke, W. Lithium−air battery: promise and challenges. J. Phys. Chem. Lett.
2010,
1, 2193-2203.

(3)  Christensen, J.; Albertus, P.; Sanchez-Carrera, R. S.; Lohmann, T.; Kozinsky, B.; Liedtke, R.; Ahmed, J.; Kojic, A. A critical review of Li/air batteries. J. Electrochem. Soc.
2012,
159, R1-R30.

(4)  McCloskey, B. D.; Valery, A.; Luntz, A. C.; Gowda, S. R.; Wallraff, G. M.; Garcia, J. M.; Mori, T.; Krupp, L. E. Combining accurate O2 and Li2O2 assays to separate discharge and charge stability limitations in nonaqueous Li-O2 batteries. Journal of Physical Chemistry Letters
2013,
4, 2989- 2993.

(5)  Viswanathan, V.; Thygesen, K. S.; Hummelshoj, J. S.; Norskov, J. K.; Girishkumar, G.; McCloskey, B. D.; Luntz, A. C. Electrical conductivity in Li2O2 and its role in determining capacity limitations in non-aqueous Li-O2 batteries. J. Chem. Phys.
2011,
135, 214704.

(6)  Luntz, A. C.; McCloskey, B. D. Nonaqueous Li–air batteries: a status report. Chemical Reviews
2014, Article ASAP.
Analysis of Diffusion Behavior in Lithium-Air Batteries Via Simulated and Experimental Impedance Spectroscopy and Equivalent Circuit Modeling
Authors: Nelson Ruben , Weatherspoon Mark H.
Published: February 2020

Porous electrodes offer the advantage of high surface area in a compact structure and play an important role in the diffusion process in batteries.  Particular to lithium-oxygen (Li-O2) batteries, diffusion of oxygen from an external source complicates transport properties due to the consideration of multiple active species at multiple phases and oxygen diffusion complexity. General diffusion from transport processes that normally result in relaxation time constants then may not apply.  Instead a complex frequency response may occur, which may be explained by blocking electrode behavior. 

In Li-O2 cells featuring binder-free electrodes with metal oxide catalyst material (1), rough surfaces and possible non-uniform current distribution may generate interesting impedance spectra from stochastic errors and depressed time constants.  Previous studies by de Levie (2) and Bisquert (3-5) generally investigate via transmission line circuit models the impedance exhibited by porous electrodes.  This work aims to apply the basis of a transmission line model like Figure 1 with the experimental impedance spectra of a Li-O2 cell with a lithium metal electrode and a carbon cloth coated cobalt, manganese composite oxide discharged and charged more than ten times (6).  The circuit model estimates the thickness of the oxide, or length of the model pore, in terms of the number of resistor-constant phase elements (R-CPE), and the impedances along the line.  The observed diffusion impedance and its frequency dispersion estimated by repeated R-CPE elements includes a terminating impedance at the end of the line, indicating what the impedance at the boundary where diffusion of the species to the electrode surface should occur.  The impedance spectra of the experimental cell has high negative reactance values at the lower frequencies as shown in Figure 2.  This capacitive nature is suggestive of a blocking behavior exhibited by electrodes where little faradaic current or charge transfer occurs, such as in the case of electrodes completely coated by a nonconductive oxide.

Acknowledgements

This work was supported by the ERC program of National Science Foundation under award number EEC-08212121.

References

1. J. Gomez, E.E. Kalu, R. Nelson, C. Akpovo, M.H. Weatherspoon, J.P. Zheng, ECS Electrochemistry Letters, 1, (2012) D25-D28.

2.  R. De Levie, Electrochimica Acta, 8, (1963) 751-780.

3.  J. Bisquert, Physical Chemistry Chemical Physics, 2, (2000) 4185-4192.

4.  J. Bisquert, G. Garcia-Belmonte, Á. Pitarch, ChemPhysChem, 4, (2003) 287-292.

5.  J. Bisquert, A. Compte, Journal of Electroanalytical Chemistry, 499, (2001) 112-120.

6.  R. Nelson, M.H. Weatherspoon, J. Gomez, E.E. Kalu, J.P. Zheng, Electrochemistry Communications, 34, (2013) 77-80.

Figure 1
In Situ Observation of Sodiation and Magnesiation of ZnO Nanowire Compared to Lithiation Process
Authors: Asayesh-Ardakani Hasti , Nie Anmin , Klie Robert F , Shahbzian-Yassar Reza
Published: February 2020

The over-growing demand of high capacity storage for application in electrical vehicles and green power backup energy has triggered the new battery concept search beyond Li-ion. Na-ion and Mg multivalent rechargeable batteries are recent concepts. The natural abadency of Na and Mg on earth makes these batteries more eco-friendly and affordable.  Another considerable issues in batteries are performance and cyclability of batteries. The anode materials usually experience large volume changes through the ion insertion and extraction. This volume change and lithium embrittlement usually causes cracks and loss of contact in the anode material, which ultimately causes the failure of battery. Here, we investigated and compared the structural and mechanical changes of ZnO nanowires during sodiation and magnesiation to lithiation process by using in situ transmission electron microscopy. The cracks were created upon the first lithiation process of single crystalline ZnO nanowire. The lithiated ZnO nanowire shows multiple glassy domains, which has low strength and ductility. This results in poor cyclability of battery. On the other hand, ZnO nanowires do not show any cracks and degradation after sodiation and magnesiation. The direct comparison between Na and Mg-ion batteries to most consumed Li-ion battery would pave the new search for high capacity battery.