Modern All Solid-State Batteries (ASSBs) with composite electrodes (i.e. made of blends of active material and electrolyte particles) give the promise of high energy density storage devices. However, they usually have significant performance limitations due to limited ionic and electronic percolation within the composite electrodes. Furthermore, mechanical aging is expected to impact the battery cell power-density as fracture in the electrolyte represents a barrier for lithium ion transport inducing rate performance decay.

This PhD thesis aims to develop a deep understanding of ASSB working principles by developing and experimentally validating an unique computational model accounting in 3D for the composite electrode microstructure and its corresponding evolution upon electrochemical cycling. Such a model will consider the interplays between electrochemical reactions, ionic and electronic transport and mechanics. The model will be able to calculate pressure fields as function of applied pressure on the cell, track microstructure evolution and its impact on the galvanostatic charge-discharge profiles. The electrode microstructures will consider realistic particle shapes and sizes. The latter will be characterized using Scanning Electron Microscopy and Computer Tomography (CT). The microstructures will arise from electrode manufacturing process simulations performed by another DESTINY PhD student (Cohort #1) and from CT characterizations. The simulations and experimental characterizations will focus in particular on active material volume changes, cracking, loss of contact between active material and electrolyte particles, as well as implicated mechanical stresses, as function of formulation, particle size distributions (and modality) and their shapes. For that, tape casted electrodes will be fabricated and implemented in electrochemical devices in order to perform electrochemical experiments such as EIS spectroscopy and galvanostatic measurements. The model should allow providing guidelines for the microstructure optimization in terms of mechanical stability. A starting point for this fascinating model will be an adaptation of the methodology for simulating mechano-electrochemistry in Lithium Ion Batteries recently developed by the LRCS team.

Secondment will take place at UMICORE for 3 months in Olen, Belgium.

Supervisor(s) contact:
FRANCO, Alejandro A. alejandro.franco@u-picardie.fr

SEZNEC, Vincent vincent.seznec@u-picardie.fr