Symposium SF12—Bioinspired Structural Composites—Advances in Experiments, Simulations and AI-Based Design

Luke Henderson, Deakin University

Modifying Composite Interfaces to Maximize Physical Performance and Functionality

Written by Henry Quansah Afful

Carbon fiber composites (CFRP) have shown potential for use in energy storage applications such as electrodes in car batteries. “The main challenge facing carbon fibers in energy storage is their very small surface area,” says Henderson. Some approaches attempted to increase the surface area sacrifice some mechanical properties of the carbon fiber. Henderson addressed this problem by grafting a conductive polymer (polyaniline) to the carbon fiber surface using a new, relatively easier method developed in his laboratory. A reductive potential is applied to the fibers in an electrochemical bath which reduces the polymer in the electrolyte, setting up a chain of reactions to graft the polymer to the fiber surface. Henderson used this method for different polymer chemistries and layers and demonstrated an increase in the tensile strength of the composite by up to 45%. This increase was due to the reinforcement of defects on the fiber surface from the grafting. Also, this method improved the polymer adhesion on the fiber surface by up to 215% higher than what is obtained conventionally.

The Rise of 2D Halide Perovskites – Symposium X speaker Aditya Mohite of Rice University

Two-dimensional halide perovskites (2D-HaP) are a sub-class of 3D perovskites, which have emerged as a new class of solution-processed organic-inorganic (hybrid) low-dimensional semiconductors. 2022 MRS Spring Meeting Symposium X speaker Aditya Mohite discusses his work on 2D-HaPs ranging from the fundamental light-induced structural behaviors, and solvation dynamics to control homogeneity of layer thickness, novel photo-physical behaviors, charge transport and their role in a high-efficiency optoelectronic device, with technologically relevant durability. Mohite's presentation can be viewed online through June 30, 2022.



Symposium EN06—Solid-State Batteries—From Electro-Chemo Mechanics to Devices

Munekazu Motoyama, Kyushu University

The Influence of Temperature on Li Plating/Stripping at Metal/Oxide Solid Electrolyte Interfaces

Written by Xinzi He

Oxide solid electrolytes (Li-ion conductors) are non-flammable and have no risk of releasing toxic gas. Munekazu Motoyama started the talk with two mechanisms of short-circuiting: the isolated void formation on the interface and hydrostatic pressure of Li at the flaw. Prof. Motoyama then introduced his systematical study on how different factors, including temperature, area, pressure, and interface wetting, would influence the critical current density (CCD) for short-circuiting using Li6.6La3Zr1.6Ta0.4O12 (LLZT) solid electrolyte. The CCD was found to increase with the increase of the temperature and the increase of the LLZT thickness. Moreover, the activation energies of the CCDs were also discussed. An important founding is that the improvement of the wettability between Li and LLZT does not help increase the CCD. At the end, Prof. Motoyama and the audience also discussed the experiment setup on the electrode constructions.

Symposium SF07—In Situ Material Performance and Dynamic Structure Characterization Under Coupled Extremes

Daniel Kiener, Montanuniversity Leoben

Size Affected Toughening and Strain Rate Sensitivity of Silicon

Written by Henry Quansah Afful

It is a well-known phenomenon that nanostructured materials are much stronger than their bulk counterparts but this usually limits their fracture toughness. Can we emit dislocations that will blunt the crack tip and thereby increase the fracture toughness in these nanostructured materials? Kiener demonstrates this phenomenon in nanostructured silicon (Si) using in situ transmission electron microscope (TEM) at room temperature. Kiener created a notch in the material along some crystallographic orientation to act as a stress concentration site. TEM images reveal the nucleation of dislocations from the crack tip in <250 nm-thick Si which blunted the crack tip and increased the fracture toughness by a factor of 3 from what is observed in bulk Si. Dark field mode in TEM revealed the absence of these dislocations prior to the bending test proving that these were formed during the test. The presence of this intrinsic toughening mechanism in Si makes it more damage-tolerant and useful for microelectromechanical devices.

Plenary Session Featuring The Fred Kavli Distinguished Lectureship in Materials Science - MRS-TV Interview

Sossina Haile of Northwestern University discusses her Plenary address to the 2022 MRS Spring Meeting, titled “Vignettes in Solid State Electrochemistry for Sustainable Energy Technologies.” Haile's presentation can be viewed online through June 30, 2022.



2022 MRS Spring Meeting "Science as Art" winners

Symposium EN06—Solid-State Batteries—From Electro-Chemo Mechanics to Devices

Peter Bruce, University of Oxford

Factors Influencing the Critical Current in Lithium Anode Ceramic Electrolyte Solid-State Batteries

Written by Xinzi He

The critical current density (CCD) for solid-state batteries pairing with a lithium anode is always discussed in the scenario of dendrite penetration. Peter Bruce started the talk by pointing out that the void formation on the lithium stripping side can be another critical reason that makes the CCD smaller than the dendrite-penetration-controlled one. Moreover, using x-ray computed tomography, the location where dendritic cracks initiate and propagate were revealed. The cracks were found driven by Li at the back of the crack, not the tip. An important lesson found is lower stacking pressure can be more favorable to achieving higher CCD without crack propagation. In the end, together with the session chair Prof. Matt McDowell (Georgia Institute of Technology) and Prof. Xin Li (Harvard University), Prof. Bruce discussed how the cell structures design—with and without lateral restriction—may influence these crack phenomena.

Symposium SF09—High Entropy Materials II—From Fundamentals to Potential Applications

Dmitri Louzguine-Luzgin, Mathematics for Advanced Materials-OIL, National Institute of Advanced Industrial Science and Technology

High Entropy Approach Starting from a Corner of the Phase Diagram in Designing High Strength Fe–Based Alloys

Written by Henry Quansah Afful

Solid solutions can be easily formed by following Hume-Rothery rules and this also applies to high entropy alloys (HEA). In essence, the atomic radii of the solute and solvent must not be different by more than 15% and crystal structures must be similar. The low yield strength of HEAs has been attributed to the disorder in these compositions and introducing some amount of ordering (small or medium range) can enhance the strength. Louzguine-Luzgin tested some HEAs having the Fe–Mn–Al–C base system, and by starting from the corner of the phase diagram, added varying amounts by mass of Co and Ni to replace a portion of Fe and Mn. The compositions tested had both face centered cubic (FCC) and body centered cubic (BCC) phases but the BCC phase was ordered. The Fe–Mn–Co–Al–C alloys formed had high tensile plasticity of 10% and high yield and ultimate strength values of up to 1590 MPa and 1650 MPa, respectively. Louzguine-Luzgin attributed the high strength values to solid solution hardening and deformation strengthening from the thermomechanical treatments.

Symposium EN05—Emerging Materials for Electrochemical Energy Storage Devices—Degradation and Failure Characterization—From Composition, Structure and Interfaces to Deployed Systems

Yazhou Zhou, Stevens Institute of Technology

Suppressing Volume Change in the Li Metal Anode via Three-Dimensional Current Collector Construction for Anode-Free Batteries

Written by Xinzi He

Yazhou Zhou started the talk with the introduction of the challenges of poor Coulombic efficiency and substantial volume change toward the practical application of anode-free batteries. Yazhou utilized a novel technique of electro-writing to fabricate a three-dimensional (3D) current collector. The complex 3D polymer structures consist of polymer microfibers with a uniform diameter of ~20 µm, which enables the stable formation of uniform solid-electrolyte interphases (SEI) and allows extended (>150 times) cycle life at 1 mA cm-2. In the end, Yazhou emphasized the great opportunities this unique method could provide for scalable and safe anode-free batteries.