Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session C20: Energy Storage: Towards High Capacity ElectrodesFocus
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Sponsoring Units: GERA Chair: Carlos Gutierrez, Sandia Natl Labs Room: LACC 308B |
Monday, March 5, 2018 2:30PM - 3:06PM |
C20.00001: Nanoporous-Carbon Based Anode Materials for Increased Li-Ion Energy Specific Capacity Invited Speaker: Michael Siegal Li-ion intercalation into graphite anodes has an optimized practical (theoretical) specific capacity ~ 330 (370) mAh/g. With both sides of each sheet accessible for lithiation, graphene has double the specific capacity, but experiences low coulombic efficiency and capacity fade from Li-loss to the solid-electrolyte interphase (SEI) with repeated cycling. Instead, we study nanoporous carbon (NPC). NPC self-assembles at room-temperature during pulsed-laser deposition. NPC mass density (and surface area) is controlled via deposition energetics from 2.25 g/cm3 (~ graphite) to below 0.1 g/cm3, consisting of randomly aligned graphene sheet fragments with interplanar spacings expanded compared to graphite. Controlling these NPC properties enables a binderless study of Li intercalation vs. nanostructure, correlating electrochemical results with charge/discharge rate, mass density, and film thickness. |
Monday, March 5, 2018 3:06PM - 3:18PM |
C20.00002: Generalized Synthesis of Highly Heteroatom Doped Ordered Mesoporous Carbons for Energy Storage Yanfeng Xia, Zhe Qiang, Bryan Vogt Heteroatom doped carbon materials represent one of the most common materials for energy applications, such as fuel cells, batteries, hydrogen storage or supercapacitors. For Li+ batteries, the lithium-ion storage capacity for heteroatom doped carbon largely depends on the heteroatom doping level. Similarly for Li/Na-S batteries, heteroatom doping can decrease polysulfide shuttling through the favorable interaction between polysulfides and the polarized carbon matrix. One challenge to inhibit shuttling is achieving high heteroatoms doping in the carbon, while maintaining porosity for transport. Here we demonstrate a generalized synthesis for highly doped ordered mesoporous carbons through infiltration of molten dopants in silica reinforced mesoporous crosslinked polymer (resol) and subsequent carbonization. This method is demonstrated to generate ordered mesoporous carbons with high heteroatom content (up to 26 at% N, 15 at% B, 7 at% P, or 4 at% S) for a wide variety of elements through melt infusion of the appropriate heteroatom precursor (melamine, boric anhydride, ammonium dihydrogenphosphate or dibenzyl sulphide).We demonstrate that the high doping content can nearly fully inhibit polysulfide shuttling in Na-S batteries. |
Monday, March 5, 2018 3:18PM - 3:30PM |
C20.00003: Synthesis and Electrochemical Characterization of Titanium Carbide (TiC) Nanowires Justin Ramsey, Milinda Wasala, Austin Peterson, Chung-Ying Tsai, Kanchan Mondal, Saikat Talapatra Titanium Carbide (TiC) is a material which has recently been used in a variety of applications as a bulk material, such as hard coatings for drill bits, heat shields, and in catalysis. It also shows promise at the nanoscale and has many favorable properties which may make it useful in electrochemical energy storage systems. Here we will report on our efforts in synthesis of TiC nanowires using a cost-effective route. Results of structural characterization using electron microscopy and X-ray diffraction (XRD) will be presented. Electrical measurements performed in order to understand the nature of electrical conductivity in assemblies of such nanostructures will be presented and discussed. A detail electrochemical characterization through cyclic voltammetry, charge discharge and electrochemical impedance spectroscopy of assembled sheets of TiC nanowires will be presented and the possibility of developing these materials for super capacitor electrodes will be discussed. |
Monday, March 5, 2018 3:30PM - 3:42PM |
C20.00004: Synthesis, in-situ TEM characterization and electrochemical behaviors of Sb2Te3/C nanocomposite for sodium-ion batteries Jingying Sun, Ze Yang, Yizhou Ni, Zhenhuan Zhao, Jiming Bao, Shuo Chen The limited resource of Li cannot satisfy the rapid development of Li-ion batteries applications. Na-ion battery is respected as a potential alternative because Na possesses the abundant storage. Sb-based anode materials are attracting more attention owing to the high capacity, but the poor cyclic property caused by the huge volume change during sodiation and desodiation is still a problem. Usually, the cyclic performance is improved by introducing inactive elements but sacrificing the capacity simultaneously. Here, we introduce Na-active Te to Sb2Te3/C nanocomposite where Sb2Te3 nanocrystals (~20 nm) embedded in the carbon matrix, via a high-energy ball-mill method. The specific capacity of Sb2Te3/C electrode could deliver 360 mA h g–1 at 1 A g–1. Moreover, its capacity retention is as high as 93% after 400 cycles. In-situ TEM analysis indicates that the stress during volume change can be released and the pulverized nanoparticles aggregation can be suppressed efficiently by the synergetic effects of carbon matrix and nanosized particles. |
Monday, March 5, 2018 3:42PM - 3:54PM |
C20.00005: In situ Optical Microscopy of Electrically-Driven Lithium Intercalation Dynamics in Graphite Jared Lodico, Mark Woodall, Ho Chan, Erick Garcia, William Hubbard, B. Regan Using optical microscopy we observed lithium intercalation and deintercalation in a micro-scale graphite electrode. Graphite was mechanically exfoliated and transferred via wet processing techniques to a pre-patterned nickel electrode. Then the nickel electrode was encapsulated with insulating Al2O3 using atomic layer deposition to minimize the nickel background contribution to the electrochemical currents. The counter and reference electrodes were lithium foil, the electrolyte was 1M LiClO4 in EC:DMC, and the experiments were conducted in an argon atmosphere at room temperature. We tracked the graphite’s color, which is directly related to its lithium content, as it evolved through grey, blue, red, and gold during multiple intercalation cycles. These color changes reveal that the intermediate lithium carbide structures adopted by the electrode during intercalation do not appear in reverse sequence during deintercalation. In other words, the deintercalation pathway is not the time-reverse of the intercalation pathway. |
Monday, March 5, 2018 3:54PM - 4:06PM |
C20.00006: Single-Step Flash-Heat-Treatment Synthesized Flame-Retardant Red Phosphorus/Graphene Composite as Flexible Anode for Sodium-Ion Batteries Yihang Liu, Anyi Zhang, Chenfei Shen, Qingzhou Liu, Jiansong Cai, Xuan Cao, Chongwu Zhou Among all of the anode materials for Na-ion batteries, phosphorus guarantees its role with the high theoretical specific capacity of ~ 2600 mAh/g, and the red phosphorus (RP) is the most cost-effective allotrope. In this work, a facile single-step flash-heat-treatment synthesis method was developed to realize the reduction of graphene oxide (GO) and deposition of RP onto the reduced graphene oxide (rGO) sheets simultaneously, and the resulted RP/rGO composite has been subsequently demonstrated to solve the poor electronic conductivity and large volume variation issues of RP during cycling. The RP/rGO flexible film anode achieved an average capacity of 1625 mAh/g during the 200 cycles at 1 A/g charge/discharge current density. Average charge capacities of 1786, 1597, 1324 and 679 mAh/g at 1, 2, 4, and 6 A/g current densities were obtained in the rate capability test, respectively. Moreover, the RP/rGO film also presented excellent flame retardancy over the rGO film by taking the advantage of the RP ingredient. |
Monday, March 5, 2018 4:06PM - 4:18PM |
C20.00007: Theoretical Exploration of Stable and Meta-Stable Li-Sn Compounds for Understanding the Reaction Mechanism of Sn Anode in Li-ion Batteries Raja Sen, Priya Johari It is already been shown that at high pressure several exotic and unusual stoichiometries can be obtained, that may even survive decompression from high-to-ambient pressure with improved mechanical properties. With a belief that hydrostatic pressure may also help in realizing Li-richer (x > 4.25) Li-Sn compounds, we performed extensive calculations using the evolutionary algorithm and density functional theory to explore all stable and possible low energy metastable Li-Sn compositions at a pressure ranging from 1 atm to 20 GPa. Besides the experimentally known Li-Sn compounds, our study reveals the existence of five unreported stoichiometries (Li8Sn3, Li3Sn1, Li4Sn1, Li5Sn1, and Li7Sn1). While Li8Sn3 has been identified as one of the most stable Li-Sn compounds in the considered pressure range with R-3m symmetry, the Li-rich compounds are predicted to be metastable at ambient pressure and found to get thermodynamically stable at high pressure. Here, the discovery of Li5Sn1 and Li7Sn1 opens up the possibility to integrate them as a prelithiated anode as compared to known Li4.25Sn, as void-space engineering by using a LixSn phase as a pre-lithiated anode, with an optimal value for x, may help in improving mechanical integrity and reducing pulverization in Li-ion batteries. |
Monday, March 5, 2018 4:18PM - 4:30PM |
C20.00008: In Situ and Ex Situ Transmission Electron Microscopy Study of Lithiation Behaviours of Porous Silicon Nanostructures Chenfei Shen, Mingyuan Ge, Langli Luo, Xin Fang, Yihang Liu, Anyi Zhang, Jiepeng Rong, Chongmin Wang, Chongwu Zhou In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanostructures transform to crystalline Li15Si4 phase while porous Si nanostructures transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanostructures during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanostructures. |
Monday, March 5, 2018 4:30PM - 4:42PM |
C20.00009: Computational Study of the O2/Li+-O2- Redox Couple in Li-Air Batteries Emily Crabb, Eric Fadel, Jeffrey Grossman Lithium-air batteries are an active area of research because of their potential to have a much higher energy density (per unit mass) than traditional lithium-ion batteries but are not yet commercially viable due to poor efficiency, high charging voltages, and low cycle lifetimes. It has been found experimentally that in Li-air batteries with aprotic solvents the O2 reduction starts when superoxide (O2-) forms in solvent and reacts with Li+ to form lithium superoxide (Li+-O2-) [1]. Solid Li2O2 is then formed as the final discharge product on the cathode. Recent experimental work has suggested that a better understanding of the factors governing the behavior of the lithium superoxide in solvent could help control the discharge at the cathode [1]. We have used a combination of density functional theory calculations and ab-initio molecular dynamics simulations to model the interactions of the Li+ and O2- ions in solvent and study properties such as the clustering behavior of Li+-O2-. [1] D. G. Kwabi, V. S. Bryantsev, T. P. Batcho, D. M. Itkis, C. V. Thompson, Y. Shao-Horn, Angew. Chem. Int. Ed. 2016, 55, 3129. |
Monday, March 5, 2018 4:42PM - 4:54PM |
C20.00010: Formation and Nucleation of Discharge Products in Metal-air Batteries Supported by Metal oxide Catalysts Khomotso Maenetja, Phuti Ngoepe Catalytic effect on the performance of metal air battery has been intensively studied for Li-air battery whereas, not much focus has been given to Na-air batteries yet. However, it has been reported that the most stable product in Na-air battery is NaO2 whereas in Li-air battery it has been reported that the major and stable product is Li2O2. In this work, we present density functional theory study of how metal oxide (MnO2, TiO2 and VO2) catalyst affects nucleation of Li2O2 and NaO2 and other products that may be formed. We further investigate the discharge products of these two metal air batteries compared to the known systems of the product in terms of their formation energy and their morphology. Interestingly it has been found that what was reported in literature, that the most stable products in Na-air batteries being NaO2 is indeed what has been observed in our study. Furthermore, the type of structure that has been found was the pyrite form whereas the most stable product in Li-air battery, Li2O2 has the hexagonal type. Amongst the three metal oxides, MnO2, is the most efficient catalyst because it encourages the formation of the reported stable products in both Li and Na air batteries. |
Monday, March 5, 2018 4:54PM - 5:06PM |
C20.00011: High performance supercapacitors enabled by conducting polymer-nanomaterial composites Shashi Karna, Ashwini Srivastava Electrochemical double-layer capacitors (EDLCs) have attracted a great deal of attention in recent years due to their considerably high power density, long cycle life, and low maintenance cost. However, the small double layer capacitance often limits the application of EDLCs. Here we present EDLCs composed nanocomposites that exhibit considerably enhanced power density, capacitance, and cycling life. For example, EDLC composed of graphene-PdNPs show exhibit specific apacitance of 637 F g-1, excellent cyclic performance, and maximum energy and power densities of 56 Whkg-1 and 1166 Wkg-1, respectively at a current density of 1.25 Ag-1. An EDLC composed of graphene nanosheets, AgNPs, and polyparrole exhibits specific capacitance of 450 F g(-1) at current density of 0.9 mA g(-1) and high charge discharge reversibility, retaining over 92.0% of its initial value after 1000 cycles. In addition to their superior elctrochemical performance, these EDLCs also offer promises as structural material. |
Monday, March 5, 2018 5:06PM - 5:18PM |
C20.00012: ab initio Investigation of Two-dimensional Coordination Polymers as the cathode materials for Lithium-sulfur batteries Guoping Gao, Lin-Wang Wang Rechargeable lithium-sulfur batteries are considered as next-generation energy storage systems. Tremendous progress has been made in the performance of lithium-sulfur batteries, but very few theories studies investigated the Li-S reaction mechanism in solvent solution. In this work, we use conductive 2D coordination polymers as the cathode materials and investigated the interaction behavior of LixSy on it in solvent model. Based on the these investigations, we try to develop reliable computational methods for a better understanding the the charging/discharging mechanism. |
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