“Mechanics, microstructure and interfaces in solid-state batteries”

RWTH Publications (RWTH Aachen)

Abstract

The development of Solid-State Batteries (SSBs) is a critical aspect in advancing technologies such as electric vehicles and renewable energy storage. This work investigates key scientific and engineering challenges related to the Lithium Metal Anode (LMA) and its interface with the Solid Electrolyte (SE). Through atomistic simulations, we show that lithium exhibits strong mechanical anisotropy not only in elasticity but also in plasticity, with orientation and load type-dependent deformation mechanisms and clear size effects at the nanoscale. Meanwhile, experimental studies on anode foils find that the manufacturing process significantly influences microstructure and hardness. At the solid-solid interface between the LMA and SE, alloying lithium with sodium enables pressure-free stable cycling by forming new carbonate phases and a beneficial 3D microstructure through spinodal decomposition. Via thermodynamic modeling, we identify the sodium concentration thresholds for the onset of this spinodal instability. Additionally, this thesis explores the use of Quantum Annealing (QA) as a valuable tool for energy materials simulations. We formulate mechanical deformations and interface energetics into Ising models and demonstrate the feasibility of modeling large-scale, complex systems using hybrid quantum-classical approaches. Particularly, we apply the model to lithium and predict deformation twinning in polycrystalline specimens, complementing the investigations of single crystals via atomistic simulations. The QA approach offers substantial speedups, highlighting quantum computing as a promising method in computational materials science. Overall, this research addresses the mechanics, microstructure, interface chemistry and modeling strategies essential for the advancement of SSBs. It offers multi-physics insights across many scales, ranging from atomistic behavior and continuum simulations to micro-level experiments and cell-relevant performance.

Authors 1

1. Lara Caroline Pereira dos Santos corresponding Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen