Events @ Warwick Chemistry

On Wednesday 10th May at 3pm in MB0.08, we will have a computational chemistry seminar by two of our PDRAs, Tanmoy Chakraborty and Huseyin Sener Sen, working in the Karasulu group. The seminar will be followed by drinks and snacks in G block. Everyone is welcome to come along.

"Computational Discovery of Superior Niobate Based Cathode Materials for Next-Generation All-Solid-State Lithium-Ion Battery Applications"

Speaker: Dr. Tanmoy Chakraborty

Abstract:

All-solid-state lithium-ion batteries (ASSLIBs) are at the forefront of green and sustainable energy development research. A key challenge in the development of ASSLIBs for commercial applications is to find cathode materials having superior properties than the existing ones. Using a combination of first-principles calculations and various crystal structure prediction algorithms, we explore Li3NbO4-based system to identify novel stoichiometries with improved properties as cathode materials for ASSLIB applications. Based on more than 10,000 Density Functional Theory (DFT) calculations using crystal structures obtained from ab initio random structure searching (AIRSS), genetic algorithm, and configuration enumeration procedures, we predict five novel stoichiometries, along with an experimentally known stoichiometry. All the novel stoichiometries were found to have cation disordered rock-salt crystal structures and fall within 30 meV/atom from the convex hull of the parent compositions. Excitingly, these new phases are predicted to have superior properties compared to the current niobate electrode materials, including a higher theoretical capacity, lower band gap, higher average Li intercalation voltage, minor volume change upon full delithiation, good mechanical & dynamical stability, improved Li-conduction activation barrier and high-temperature crystal stability. Our results are anticipated to inspire further experiments to synthesise and test these specific niobate-based materials for their actual performance as Li-ion cathode materials.

"Design of radiation damage tolerant Zr-Nb nanoscale metallic multilayer composite"

Speaker: Dr. Huseyin Sener Sen

Abstract:

Nanoscaled metallic multilayers systems (NMMs) represent a new generation of engineering materials, exhibiting unique properties, distinct from those of the bulk constituents because below a critical layer thickness, the strain mechanism does not follow the classic Hall– Petch relationship. These novel materials show high yield strengths, anomalous Young’s modulus values and even superior radiation tolerance for layer thicknesses up to a few tens of nanometers which make them perfect candidates as coating materials for nuclear applications. However, there are still many unknowns such as the response of the specific material to the various types of irradiation. We investigated the mechanical properties of Zr(0001)/Nb(110) metallic multilayers with varying thicknesses as well as their response to neutron and Helium irradiation. We performed both experiments and simulations to understand the mechanism and underlying physics at nanoscale. The results indicate that hcp-Zr/bcc-Nb NMMs are strong materials with high radiation tolerance which can be designed for desired application easily. For example, we propose a doping mechanism to get rid of He atoms that would accumulate inside the material and cause fractures. We also propose that ZrNb55 (Zr = 24nm, Nb = 31nm) multilayered structure has the optimal layer thickness which possesses high resistance against radiation damage and minimal swelling to ensure the structural integrity.