Functional Defects in Electroceramic Materials: On-Demand Oral Presentations
Sponsored by: ACerS Electronics Division
Program Organizers: Hui Xiong, Boise State University; Hua Zhou, Argonne National Laboratory
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 5
Location: MS&T On Demand
Invited
Dislocation-based Nanomechanics in Functional Oxides: A Case Study on SrTiO3: Xufei Fang1; Kuan Ding1; Stephan Janocha1; Christian Minnert1; Till Frömling1; Karsten Durst1; Atsutomo Nakamura2; Jürgen Rödel1; 1Technische Universität Darmstadt; 2Nagoya University
In light of the rising topic of dislocation-based functionality of oxides, the dislocation-based mechanical behavior, for instance, dislocation plasticity and potentially crack formation induced by dislocations is also drawing increasing attention. Understanding the dislocation-based mechanics in oxides can play a critical role in assessing the materials’ mechanical and functional reliability. Here we present an approach to actively engineer and evaluate the incipient dislocation plasticity and crack formation using nanoindentation. We propose the concept of “defect chemistry engineering” to actively tune the dislocation plasticity of the oxide crystals, as will be demonstrated in single-crystal SrTiO3. Two methods, i.e., via stoichiometry change of the Sr/Ti ratio, and by reduction treatment to increase oxygen vacancy concentration, have been validated to modify the dislocation nucleation and motion. Our approach may also serve as a potential method to increase the fracture toughness of the material with appreciable dislocation plasticity achieved.
Invited
Leveraging Structure and Energetics to Enhance Electrochemical Kinetics in Batteries: Kai He1; 1Clemson University
The power density of rechargeable ion batteries is one of the key limiting factors for their applications in large-scale and energy-intensive applications, which is closely correlated to the kinetics of the ionic conduction and electrochemical reaction of the electrode materials. Recent advancement of transmission electron microscopy (TEM) has enabled unprecedented capabilities to allow in situ visualization of the spatiotemporal evolution of nanoscale structural and chemical pathways. Here, we use various in situ TEM techniques to show how to leverage the structure, energetics, and strain engineering to facilitate alkali-ion reaction kinetics and improve the microstructural stability upon prolonged cycles. Through the combination of in situ TEM characterizations, electrochemical measurements, first-principles calculations, and electrochemo-mechanical modeling, we have uncovered the mechanistic understanding of the structure-kinetics relationship that may be further leveraged as design principles for next-generation lithium-ion and beyond-lithium energy storage technologies.
Invited
Modeling the Electrical Double Layer at Solid-state Electrochemical Interfaces: Yue Qi1; Michael Swift2; James Swift3; 1Brown University; 2Michigan State University ; 3Northern Arizona University
Models of the electrical double layer (EDL) at electrode/liquid-electrolyte interfaces no longer hold for all-solid-state electrochemistry. Here we show a more general model for the EDL at a solid-state electrochemical interface based on the Poisson–Fermi–Dirac equation. By combining this model with density functional theory predictions, the interconnected electronic and ionic degrees of freedom in all-solid-state batteries, including the electronic band bending and defect concentration variation in the space-charge layer, are captured self-consistently. Along with a general mathematical solution, the EDL structure is presented in various materials that are thermodynamically stable in contact with a lithium metal anode: the solid electrolyte Li7La3Zr2O12 (LLZO) and the solid interlayer materials LiF, Li2O and Li2CO3. The model further allows design of the optimum interlayer thicknesses to minimize the electrostatic barrier for lithium ion transport at relevant solid-state battery interfaces.
Invited
Defect-promoted Sulfur Cathode for Highly Stable Sodium-sulfur Batteries: Weiyang Li1; 1Dartmouth College
Room-temperature sodium-sulfur batteries hold great promise as the next-generation cost-effective energy storage systems. However, their practical implementation is still plagued by the low reversible capacity of a bulk-sized commercial sulfur cathode with low Coulombic efficiency and poor cycling stability. Here, we present a highly stable room-temperature sodium-sulfur battery using a facile-processed, nanocarbon-promoted, bulk-sized commercial sulfur cathode. This processed nanocarbon possesses a high binding affinity to sulfur and polysulfides, largely facilitating the sulfur reaction kinetics and leading to high reversible capacity. DFT calculation demonstrates that the abundant defects in the processed nanocarbon could contribute to the increased sulfur cathode capacity. Meanwhile, by applying a thin coating of the defect-rich nanocarbon on the polymer electrolyte, dead sulfur formation can be avoided, contributing to greatly enhanced capacity retention. The sodium-sulfur battery delivers a reversible capacity of >700 mAh/g with near-100% Coulombic efficiency and ultrahigh capacity retention of 98.2% at 0.2C after 200 cycles.
Invited
Irradiation-enhanced Electrochemical Performance of TiO2 Anode Material: Janelle Wharry1; Chao Yang1; Tristan Olsen2; Hui (Claire) Xiong2; Kassiopeia Smith3; Yongqiang Wang4; Khalid Hattar5; Yaqiao Wu2; Dmitri Tenne2; Sheng Cheng2; 1Purdue University; 2Boise State University; 3National Institute of Standards and Technology; 4Los Alamos National Laboratory; 5Sandia National Laboratories
The objective of this study is to understand the effect of irradiation-induced defects on electrochemical charge storage capacity in TiO2 electrodes. Cation defects in metal oxide anodes for lithium-ion batteries are known to increase the extent of Li intercalation, and thus increase the charge storage capacity. Here, we utilize irradiation to intentionally produce defects in TiO2 metal oxide anode. We conduct room-temperature Nb ion irradiations on rutile [100] TiO2 single crystals, then subsequently carry out lithiation. Li pickup is enhanced along irradiation damage tracks and at the Nb ion implantation peak. We also observe irradiation-enhanced electrochemical cycling in both anatase and amorphous TiO2 nanotubes. This improved performance is attributed to irradiation-induced defects and disordering in the anatase tubes, and irradiation-induced crystallization in the amorphous nanotubes. These results are discussed in the context of irradiation-induced order/disorder transformations.
Dislocations as “Self-dopants” in Functional Oxides, Exemplified for TiO2: Qaisar Muhammad1; Lukas Porz1; Atsutomo Nakamura2; Katsuyuki Matsunaga2; Marcus Rohnke3; Jürgen Janek3; Till Frömling1; Jürgen Rödel1; 1Technical University of Darmstadt; 2Nagoya University; 3Justus Liebig University
Dislocations as heavily charged line defects have so far been underappreciated as a means to tune functionality but are finding increasing attention today. To modify electrical properties of rutile (TiO2), (prevalent due to its applications; for example, gas sensors) defect engineering via chemical doping has an important role. However, often the solubility limits of the dopant restricts this method for tailoring material properties significantly while it increases material complexity.Here, we demonstrate the possibility to induce equivalent conductivity enhancements akin to conventional chemical doping by mechanically introduced dislocations. By controlling the mesoscopic structure of dislocations, we are able to both enhance and reduce conductivity. These changes are documented by temperature and oxygen partial pressure dependent conductivity measurements. In this way, the prospect of dislocations as “self-dopants” is presented, where the additional design parameter of the dislocation arrangement renders them potentially superior to conventional chemical doping strategies.
Ceramics Are Brittle. Can Dislocations Change That?: Lukas Porz1; Arne Klomp1; Xufei Fang1; Ning Li2; Can Yildirim3; Carsten Detlefs3; Enrico Bruder1; Marion Höfling1; Wolfgang Rheinheimer4; Eric Patterson5; Peng Gao2; Karsten Durst1; Atsutomo Nakamura6; Karsten Albe1; Hugh Simons7; Jürgen Rödel1; 1Technical University of Darmstadt; 2Peking University; 3European Synchrotron Radiation Facility; 4Forschungszentrum Jülich; 5US Naval Research Laboratory; 6Osaka University; 7Technical University of Denmark
While the effect of dislocations on functional properties is increasingly appreciated, dislocations have barely been considered for toughening ceramics. Despite outstanding deformability of a range of ceramic single crystals (e.g., LiF, MgO or SrTiO3) at room temperature, an effect of dislocations on fracture toughness was rarely observed. Why? Here, we show that introducing a high dislocation density can allow local plasticity which is key for desirable mechanical properties. With local deformation enabled, stress concentrations around flaws or indents can be mitigated by plastic flow. In effect, crack nucleation and propagation are substantially reduced [1]. In consequence, dislocations can be a new avenue to combat short cracks and increase device reliability. Conventionally sintered samples, however, are not suitable as this process renders ceramics dislocation-free.1)Porz et al., Materials Horizons, 2021 (DOI:10.1039/d0mh02033h)