Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session A47: Energy Storage: Cathodes and Supercapacitors |
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Sponsoring Units: GERA Chair: Michelle Johannes, United States Naval Research Laboratory Room: BCEC 213 |
Monday, March 4, 2019 8:00AM - 8:12AM |
A47.00001: Facet dependent cation segregation in layered lithium transition-metal oxide cathode materials Hakim Iddir, Juan Garcia, Javier bareño, Guoying Chen, Jason Croy The development of energy storage devices with enough power and energy density, long term stability, and extended cycle life that are capable of meeting environmental constraints is an important challenge for modern electrochemistry. Lithium-ion batteries are the primary energy storage devices for electric vehicles. However, there are still challenges for making this technology more competitive. Improving the understanding of the fundamental processes taking place in such materials is a prerequisite to accomplish any significant improvement. For example, the segregation of transition metals (TM) from the bulk to the surface of typical cathode-oxide particles plays a critical role in the formation and composition of surface reconstruction layers (SRL) that appear on pristine and cycled materials. Such layers have been indicated as the origin of cathode impedance rise with cycling, and hence, may significantly decrease the performance of batteries. The origin and thermodynamic driving force for such segregation processes are not clear yet. In the present work, we propose a facet dependent TM segregation/phase-change mechanism to explain observed experimental results. |
Monday, March 4, 2019 8:12AM - 8:24AM |
A47.00002: LiFePO4-Carbon Nanofiber Composite Cathodes for Li-ion Batteries Adewale A. Adepoju, Quinton L Williams LiFePO4 offers interesting possibilities as a cathode material for Li-ion batteries because of its steady operating voltage, excellent structural stability, nontoxicity, and inexpensive source materials. However, its poor electronic conductivity is a major challenge for commercialization. Although different techniques have been developed to address this problem, we approach this challenge by incorporating carbon nanofibers (CNFs) as conductive additives in the LiFePO4 cathode material. CNFs have high electrical conductivity and high aspect ratio. The effect of adding different percentages of CNFs to LiFePO4 cathodes was investigated using scanning electron microscopy (SEM), four-point probe, and electrochemical measurements. Electrochemical testing showed the LiFePO4 with few percents CNFs added to the composite cathode exhibited excellent rate capability performance at 20C and higher cycling capacity with less fading over 200 cycles at 5C. This improved performance is attributed to the increase in electronic percolation pathways created by adding CNFs. |
Monday, March 4, 2019 8:24AM - 8:36AM |
A47.00003: First principles theory of unanticipated electron transfers in new organic energy-storage materials: application to phenothiazine-based polymer cathodes. Mariel Tader, Brian Peterson, Héctor Abruña, Brett Fors, Tomas Alberto Arias Organic polymer cathodes have promise as low-cost, environmentally clean, lightweight alternatives to traditional inorganic battery cathodes, but are limited by their instability. To explain the observed limits to the charge capacity of PT-DMPD, a phenothiazine-based organic material, we utilize recently developed Joint Density Functional Theory (JDFT) methods to study electron transfer (redox) events. Comparing to experimental cyclic voltammetry (CV) data, we find that electron transfer from the primary PT-DMPD redox sites actually occurs at lower voltages than anticipated. As a consequence, batteries using this and related materials have been operated at voltages where some of the primary redox reactions have actually already occurred, so that, during operation, unexpected redox centers are accessed. These new centers weaken important structural bonds, perhaps explaining the observed loss of capacity of PT-DMPD cathode batteries with cycling. These findings suggest a pathway for design of more power dense, stable energy storage materials. |
Monday, March 4, 2019 8:36AM - 8:48AM |
A47.00004: Electrogenerated Hexacyanoferrate Thin Films for Battery Applications Else Amanda Rensmo, Scott D Joffre, Jennifer R Hampton Prussian Blue Analogues such as transition metal hexacyanoferrates (HCFs) have gained increasing interest as materials for energy storage applications, as they provide enhanced stability due to their open framework structure and potential for reduced cost by use of earth-abundant materials. Using Ni, NiCo and NiCu substrates, a variety of alloy HCF films were electrogenerated by cyclic in the presence of hexacyanoferrate. For NiCo- and NiCu-based HCF materials, the charge storage and transport properties were measured and compared to Ni-HCF to explore the effects of the addition of alloying metals. The addition of Co or Cu in the substrate results in a small increase in the total stored charge, but no observable trend in the transport kinetics. For Ni-HCF, the total amount of Fe in the resulting material was measured both electrochemically and with x-ray spectroscopic methods. Unexpectedly, the spectroscopic measurements were smaller than the electrochemical ones, indicating there must be additional electrochemical reactions occurring in the presence of the HCF. |
Monday, March 4, 2019 8:48AM - 9:00AM |
A47.00005: Structural, Electronic, and Magnetic Properties of Li1+xMn2O4 Based on First-Principles Calculations Jinseon Park, Mina Yoon Recent studies have focused on understanding the reaction mechanisms driven by the lithiation of Li1+xMn2O4 spinels, in an effort to enhance the energy density of lithium-ion batteries. Experiments to characterize the spinels’ fundamental properties during the reaction are challenging. Thus computational/theoretical modeling is highly desirable. In this study, we identified global/local minimum structures of Li1+xMn2O4 spinels by using a global structure optimization algorithm coupled with first-principles calculations, and further characterized their basic electronic and magnetic properties, as well as their relative structural stabilities under external perturbations. Interestingly, the local Jahn–Teller distortion was found to play a governing role in determining spinels’ relative stabilities, in comparison to other key factors such as charge states of the Mn ions, positions of the Li ions, and magnetic configurations. Feasible pathways for the experimental verification of lithiation are proposed. |
Monday, March 4, 2019 9:00AM - 9:12AM |
A47.00006: Structural mechanisms in complex oxides enabling high-rate lithium-ion energy storage Kent Griffith, Kamila Wiaderek, Giannantonio Cibin, Lauren Marbella, Clare Grey The maximum power output and minimum charging time of a lithium-ion battery depend on mixed ionic–electronic conduction. We show that complex niobium tungsten oxides with frustrated polyhedral arrangements and dense μm-scale particle morphologies can rapidly and reversibly intercalate large quantities of lithium. Analysis of high-rate and multi-electron energy storage will be discussed with insights from operando X-ray diffraction, solid-state nuclear magnetic resonance spectroscopy, and multi-edge X-ray absorption spectroscopy for the recently reported crystallographic shear structure and bronze-like oxide phases[1]. Materials and mechanisms that enable lithiation of μm particles in minutes have implications for high power applications, fast charging devices, all-solid-state batteries, and general approaches to electrode design and materials discovery. |
Monday, March 4, 2019 9:12AM - 9:24AM |
A47.00007: Study of Structural Transitions, Jahn-Teller Distortion, Cyclability, and Specific Energy in P2-type NaxMO2 Na-ion Battery Cathodes William Rexhausen, Uma Garg, Nathaniel Smith, Joshua Harris, Deyang Qu, Prasenjit Guptasarma Recent years have seen an interest in exploring the viability of Na-ion based battery cathode materials. Here, we report relationships between crystal structure and properties in the NaxMO2 (M=transition metal) family of layered metal-oxide battery cathodes. Using detailed Rietveld fitting, we characterize structural transitions that occur as a result of cycling. We further report the effect of these transitions on battery cyclability, and the effect of transition metal substitution in crystal structure and distortion in Na2/3MnxFe1-xO2 (NMFO). Using specially designed transfer chambers, we have studied ex situ x-ray diffraction at different potentials in the charge-discharge cycle to examine the nature of the structural transitions both in the metal oxide planes and in the layering structure. We report specific energy, capacity, and cyclability of cells when cycling over several voltage ranges for different cathodes and find that substituents for Mn perform well when charged no higher than 4.0 V (vs. Na). Conversely, charging to 4.3 V degrades crystallinity. |
Monday, March 4, 2019 9:24AM - 9:36AM |
A47.00008: Modeling of 2D Materials for Sustainable Energy Storage: Opportunities and Challenges Vidushi Sharma, Kamalika Ghatak, Dibakar Datta In recent years, extensive research has been carried out on 2D materials to develop high-capacity anode materials for Li-ion batteries (LIBs). By first-principle calculations, we investigated the adsorption of Li on graphene with defects. We find that with controlled defect, we can achieve a maximum storage capacity of approximately 1675 for LIBs. However, despite enormous opportunities, we need to concern about several challenges such as adatom trapping at the defect sites, the effect of defects on adatoms diffusivity, microstructural changes, etc. In addition, our recent work shows that for the Si-based anode, we can achieve better electrochemical stability by coating the current collector surface with graphene sheets. Besides graphene, several other 2D materials such as graphene allotropes, Transition Metal Dichalcogenides (TMD), etc. have tremendous potential in energy applications. Moreover, by building heterostructures (stacking of different 2D materials), it is possible to combine the advantage and eliminate the disadvantages of the individual sheet. In this presentation, we will provide a detailed overview of opportunities and challenges of modeling of 2D materials and its heterostructures for the next-generation sustainable energy storage applications. |
Monday, March 4, 2019 9:36AM - 9:48AM |
A47.00009: Impact of Hybridization and Correlations on Transition-Metal Valence and Oxygen Redox in Li-ion Battery Cathode Materials Ilkyu Lee, Chunjing Jia, Brian Moritz, Thomas Devereaux Transition-metal oxide battery cathode compounds undergo distinct changes in their electronic distribution as one goes from a fully lithiated to a fully delithiated state. This would lead nominally to energetically unfavorable high valence states on the transition-metal, affecting overall energy capacity. Here, we analyze the influence of metal-to-ligand orbital hybridization and effective charge transfer using a configuration interaction cluster model to simulate different spectroscopic tools. We connect our observations to the framework of anionic redox, which prevents high transition-metal valency, and has been linked to increases in energy capacity of Li-ion batteries. By gaining insight into crucial features that are identified with such processes, we aim to have a greater understanding of the fundamental physics of Li-ion cathode materials, in the hopes of predicting novel, better performing Li-ion compounds. |
Monday, March 4, 2019 9:48AM - 10:00AM |
A47.00010: Advanced characterization of high-capacity electrodes with x-ray Compton scattering Hasnain Hafiz, Bernardo Barbiellini, Kosuke Suzuki, Gregory Houchins, Hiroshi Sakurai, Arun Bansil, Venkatasubramanian Viswanathan Li-rich layered oxides (LRLOs) have been very promising cathode materials due to their exceptionally high capacity of ~300 mAh/g and energy density of ~1000 mWh/g. However, the reaction mechanism underlying their electrochemical operation is not fully understood. Recent work on pristine cathode materials shows that Compton scattering spectroscopy can provide a useful tool to unravel the relationship between the key battery characteristics and the nature of the electronic orbitals involved in Li intercalation reactions [1]. Here, we discuss high-energy x-ray Compton scattering spectra along with parallel first-principles computations from Li1.2-xTi0.4Me0.4O2 (Me = Mn and Fe) for the purpose of developing advanced spectroscopic tools for characterizing LRLO battery materials. Our study gives insight into how we can obtain a faithful reconstruction of the redox orbitals using the Compton scattering technique. We also discuss the reversibility of the solid-state redox processes, and the related issues of lattice distortions, charge compensation, and the covalent mechanism of transition metal and oxide ions as a pathway to provide a new generation of insights into the mechanisms at play in LRLO battery materials. |
Monday, March 4, 2019 10:00AM - 10:12AM |
A47.00011: Theoretical understanding of oxygen redox feature observed on RIXS map of battery cathode materials Iwnetim Abate, Chunjing Jia, Brian Moritz, Michael F Toney, Thomas Devereaux, Sri Chaitanya Das Pemmaraju High energy density rechargeable batteries are essential to meet the ever growing global energy demand. Recently, cathode materials which have redox activity of both transition metal and oxygen are found to be very promising in this regard. However, the exact mechanism for the oxygen redox is yet to be understood. Resonant inelastic x-ray scattering (RIXS) has been established as a reliable probe of the critical oxygen states involved in battery electrodes with oxygen redox activities. The interpretation of specific O -K RIXS features; however, has not yet been achieved. To this end, we have performed theoretical calculations using new algorithm we developed to understand the spectroscopic feature from first principle. We aim to shed light on the physics of cathode materials and suggest design schemes for cathodes with exceptional capacity. |
Monday, March 4, 2019 10:12AM - 10:24AM |
A47.00012: Impact of Humidity on the Mobility of an Ionic Liquid Confined in Ti3C2TX MXene Naresh Osti, Matthew W Thompson, Katherine Van Aken, Mohamed Alhabeb, Madhusudan Tyagi, Jong Keum, Peter Thomas Cummings, Yury Gogotsi, Eugene Mamontov MXenes are two-dimensional materials with a potential in energy storage applications, especially as electrode materials in supercapacitors. MXenes provide high volumetric capacitance, but still have some limitations affecting their power capabilities. On the other hand, high energy and power density can be achieved using room temperature ionic liquids (RTILs) as an electrolyte that withstands a high operational potential window. Here, as an effort to overcome the high voltage limitation, and to provide a guidance for the development of most robust energy storage systems in the future, we have investigated the microscopic dynamics of a RTIL, [EMIm+][Tf2N-], confined in a Ti3C2TX MXene. We have found that the ionic liquid was confined between the stacks rather than in between the layers of the MXene, thus showing a diffusion coefficient at about a half of the bulk value. This result is consistent with the unchanged c-lattice parameter revealed by X-ray diffraction measurement after the ionic liquid intercalation. An increase in the overall cation diffusivity after water vapor exposure, as revelaed from quasi-elastic neutron scattering (QENS) and molecular dynamics simulations, will be presented. |
Monday, March 4, 2019 10:24AM - 10:36AM |
A47.00013: Symmetrical supercapcitors with α-MnO2 nanorods/carbon nanofiber (CNF) composite as electrode material Prasada Rao Talakonda, Ajay Kumar, Vaman M Naik, Ratna Naik α-MnO2 nanorods have been grown on the surface of CNF for enhancing the electrical conductivity of MnO2. α-MnO2/CNF (0-5 wt%) nanocomposites were synthesized using a co-precipitation method. The XRD results confirm the formation of a single phase α-MnO2 and SEM/TEM images reveal the formation of α-MnO2 nanorods. While α-MnO2/CNF(1.25 wt%) exhibits the largest surface area (381 m2/g) and only a slight increase in the electrical conductivity (0.05 S/cm), α -MnO2/CNF(5 wt%) shows the least surface area (131 m2/g) but an order of magnitude higher electrical conductivity (0.67 S/cm), compared to pure α-MnO2 nanorods. C-V measurements show improved performance in all α-MnO2/CNF supercapacitors compared to that of pure α-MnO2. Ragone plot shows that although α-MnO2/CNF(1.25 wt%) exhibits the highest specific capacitance (313 F/g at 1 A/g) and hence the highest energy density of 32.8 Wh/kg, it has a lower power density of 2720 W/kg. On the other hand, α-MnO2/CNF(5 wt%) shows the least energy density of 7.9 Wh/kg, but has a higher power density of 4640 W/kg. Results demonstrate that one can optimize both energy and power densities by controlling the amount of CNF in the nanocomposites. |
Monday, March 4, 2019 10:36AM - 10:48AM |
A47.00014: Flexible supercapacitors with vertically aligned multiwalled carbon nanotubes (MWCNT) directly synthesized on a metal foil. Thushani De Silva, Cole Damery, Robinson Karunanithy, Rana Alkhaldi, Prasanna Dnyaneshwar Patil, Milinda Wasala, Pooplasingam Sivakumar, Saikat Talapatra We will present the results of our investigation on all solid-state flexible supercapacitors using MWCNT directly grown on ultrathin Inconel foil. A poly(vinyl alcohol)/phosphoric acid (PVA/H3PO4) polymer gel has been used as both the electrolyte and the separator. Since the aligned MWCNT has a higher effective surface area and the direct synthesis on a metal decreases the resistance at the interface, these supercapacitors display improved performance with the highest measured areal specific capacitance of 19.6 mF/cm2. Key device parameters, measured and analyzed with standard electrochemical circuit modeling will also be presented. The flexibility of the devices was validated by testing them under different bending angles. These devices can withstand a large amount of such bending cycles, making them more durable and robust energy storage devices. |
Monday, March 4, 2019 10:48AM - 11:00AM |
A47.00015: Metal Organic Framework high performance supercapacitors fabricated by electrophoretic deposition Fatima Amir, Darien K. Nguyen 2 D ultrathin nanomaterials have attracted a significant interest because of their applications as energy storage devices. Metal organic frameworks (MOFs) a subset of these 2D nanomaterials are believed to be a key solution for energy storage devices such as electrochemical capacitors. In this work, we report the fabrication of the MOF Ni3(2,3,6,7,10,11-hexaaminotriphenylene)2 (Ni3(HITP)2) supercapacitor’ electrodes using electrophoretic deposition. The morphologies of the Ni3(HITP)2 electrodes were characterized using scanning electron microscopy, and transmission electron microscopy. The structure of the Ni3(HITP)2 electrodes was analyzed using x-ray diffraction. The MOF-based supercapacitor exhibited excellent capacitive performance in 0.5M Na2SO4 with an areal capacitance of 15.58mF/cm2. Furthermore, the supercapacitor exhibited an outstanding cycling stability with a capacitance retention of 81% over 50,000 cycles indicating excellent long term electrochemical stability. These results pave a promising route for the design and manufacture of a new generation of devices for energy storage applications. |
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