Advanced Materials for Energy Conversion and Storage: Functional Materials II
Sponsored by: TMS Functional Materials Division, TMS: Energy Conversion and Storage Committee
Program Organizers: Amit Pandey, LG Fuel Cell Systems Inc.

Thursday 8:30 AM
March 2, 2017
Room: 15A
Location: San Diego Convention Ctr

Session Chair: Reza Shahbazian-Yassar, University of Illinois at Chicago; Paul Ohodnicki, NETL

8:30 AM  Invited
Free the Electron: Mitigating Polaronic Bottlenecks in Cathode Materials: Sarbajit Banerjee1; 1Texas A&M University
    Limitations to the power and energy densities of Li-ion batteries constitute a major impediment to our energy future. The development of novel battery architectures and new battery chemistries is imperative to address this challenge. In recent work, we have used V2O5 as a model system to seek atomistic understanding of lithiation/delithiation pathways. Scanning transmission X-ray microscopy studies in conjunction with density functional theory suggest that polaron localization plays a key role in limiting cation mobility, giving rise to heterogeneous lithiation across individual cathode particles. As a means of circumventing polaron localization, metastable polymorphs accessible from topochemical synthesis represent a particularly useful set of compounds. I will discuss some recently discovered metastable phases that allow for unprecedented Li-ion and even multivalent cation mobility. These compounds represent particularly excellent examples of the concept of “frustrated coordination” and mitigate polaron confinement by dint of greater degeneracy of orbitals at the conduction band edge.

8:55 AM  
Increasing Ionic Conductivity with Highly Ionizing Radiation: Jacob Shamblin1; Cameron Tracy2; Rodney Ewing2; Joshua Sangoro1; Caitlin Taylor1; Maulik Patel1; William Weber1; Raul Palomares1; Eric O'Quinn1; Maik Lang1; 1The University of Tennessee; 2Stanford University
    Many complex oxides exhibiting the pyrochlore structure display ionic conductivity on the order of yttria-stabilized zirconia and thus find use as potential electrolytes in solid oxide fuel cells. Here we present a new strategy for further increasing ionic conductivity through irradiation with heavy ions of high specific energy (> 5 MeV/u). Select pyrochlore compositions (e.g., Gd2Ti2O7, Gd2Zr2O7 and Er2Ti2O7) have been irradiated at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany. Radiation-induced phase transformations include amorphization, disordering to a fluorite-type phase, and a combination of the two. Broadband dielectric spectroscopy measurements reveal that ionic conductivity in these far-from-equilibrium phases (which are stable up to about 800 C) is in some cases increased by a factor of 250 compared with the ordered pyrochlore phase prior to irradiation. This increase is due to enhanced mobility in the irradiated phases as well as an increased defect concentration.

9:15 AM  Invited
Mechanical Degradation and Optimization of Solid Electrolyte Interphases in Li Ion Batteries: Brian Sheldon1; Ravi Kumar1; Anton Tokranov1; Xingcheng Xiao2; 1Brown University; 2General Motors
    The stability of the solid electrolyte interphase (SEI) is critically important in Li-ion batteries. In particular, volume changes that occur in the active electrode materials during lithiation and delithiation can create significant mechanical deformations in SEI layers. It is difficult to probe the mechanical response of the SEI directly in complex electrodes. However, thin films provide an opportunity to investigate fundamental processes more directly. To accomplish this, we employed in situ stress, AFM, conventional in situ electrochemistry, and ex situ surface characterization. Significant differences between Si and graphitic carbon were observed in SEI growth and passivation mechanism. Both the electrolyte composition and the formation conditions had significant effects on the SEI structure and properties. The results from these experiments and corresponding models also suggest that stresses can be engineered during SEI formation, to enhance the electrochemical and mechanical integrity of these critical passivation layers.

9:35 AM  Invited
Multifunctional Graphene-based Hybrid Nanomaterials for Renewable Energy: Sanju Gupta1; 1Western Kentucky University
    Intense research in renewable energy is stimulated by global demand of electric energy. Electrochemical energy storage and conversion systems namely, supercapacitors and batteries, represent the most efficient and environmentally benign technologies. Moreover, controlled nanoscaled architectures and surface chemistry of electrochemical electrodes is enabling emergent next-generation efficient devices approaching theoretical limit of energy and power densities. This talk will present our recent activities to advance design, development and deployment of composition, morphology and microstructure controlled two- and three-dimensional graphene-base hybrids architectures with carbon nanotubes, conducting polymers, transition metal oxides and mesoproprous silicon wrapped with grapheme sheets as engineered electrodes for supercapacitor cathodes and battery anodes. They showed significant enhancement in terms of gravimetric specific capacitance, interfacial capacitance, charging-discharging rate and cyclability.1-4 We will also present fundamental physical-chemical interfacial processes (ion transfer kinetics and diffusion, imaging electroactive sites, and topography at electrode/electrolyte interface) governing underlying mechanisms via scanning electrochemical microscopy.4-6

9:55 AM Break

10:15 AM  Invited
Nanoscale Electrochemistry with In Situ Transmission Electron Microscopy: Reza Shahbazian-Yassar1; 1University of Illinois at Chicago
    Electrodes in rechargeable batteries undergo complex electrochemically-driven phase transformations upon driving Li ions into their structure. Such phase transitions in turn affect the reversibility and stability of the battery. This presentation gives an overview of the PI’s research program on in-situ transmission electron microscopy (TEM) of battery materials. In-situ TEM has been shown to be a very powerful technique in shedding light to some of the mysteries in electrochemical performance of new materials. Various anode materials including phosphorene, SnO2, and MnO2 were subjected to lithiation process and the transport of Li/Na ions was visualized within their atomic structure. We showed that twin boundaries in general provide a more accessible pathway for Li ion transport. The lithiation behavior in the presence of twin boundary defects was completely different compared to pristine state with no twin boundary defect. Anisotropic plastic deformation was also observed along [010] directions of MnO2 nanowires.

10:40 AM  
Preparation and Characterization of Eupatorium Adenophorum-derived Activated Carbon by Microwave-heating KOH and K2CO3 Activation: Li Chunyang1; Zhang Libo1; Xia Hongying1; Cheng Song1; Shu Jianhua1; 1Kunming University of Technology and Science
    Eupatorium adenophorum-derived activated carbon was prepared by chemical activation with KOH and K2CO3 at different carbonization temperature, impregnation ratio and microwave power. All of these parameters produced a high-development of porous structure. Optimized conditions were obtained at 500℃ with an impregnation ratio of 4:1 and microwave power of 800W, where apparent surface area is 1410m2/g and microporous is 0.93cm3/g. The eupatorium adenophorum-derived activated carbon present a high oxidation functional groups, due to the presence of hydroxyl on the carbon surface. Potassium is being active to form lots of microporous by evaporating in high-temperature activation process.

11:00 AM  Invited
High Energy Density Lithium Ion Battery Based on Li2O Activation: Ali Abouimrane1; Yanjie Cui2; Zonghai Chen2; Ilias Belharouak1; Hamdi Yahia1; Huiming Wu2; Rajeev Assary2; Larry Curtiss2; Khalil Amine2; 1Hamad Bin Khalifa University; 2Argonne National Laboratory
    Li2O has been successfully activated in Li-ion battery (LIB). This activation was conducted when Li2O was mixed with layer composite cathode materials such as Li2MnO3-LiMO2 (M=Mn, Ni, Co). The degree of activation depends significantly on the current rate, electrolyte salt, and anode type. The mechanism of Li2O activation will be presented and discussed. We provide a full evaluation of the possible causes of this activation. A key finding is the possible formation of a redox shuttle species during this activation. In full-cell tests, the Li2O was used as a lithium source to counter the first-cycle irreversibility of high capacity anodes. Indeed, when Li2O was mixed with a layer composite cathode material to serve as a cathode, the electrochemical performance was improved in a full cell having SiO-SnCoC composite material as an anode. Our hypothesis regarding Li2O activation can also explain the first charge plateau observed for the layer composite cathode material. These findings have implication for improving the energy density of both next generation LIB and lithium-air batteries.