Self-Organization of Electroactive Suspensions in Discharging Slurry Batteries: A Mesoscale Modeling Investigation

Abstract

We report a comprehensive modeling-based study of electroactive suspensions in slurry redox flow batteries undergoing discharge. A three-dimensional kinetic Monte Carlo model based on the variable step size method is used to describe the electrochemical discharge of a silicon/carbon slurry electrode in static mode (i.e., no fluid flow conditions). The model accounts for Brownian motion of particles, volume expansion of silicon upon lithium insertion, and formation and destruction of conducting carbon networks. Coupled to an electrochemical model, this study explores the impact of carbon fraction in the slurry and applied c-rate on the specific capacity. The trends obtained are analyzed by following the behavior of parameters such as number of contacts between electroactive particles and the percentage of electroactive silicon particles. Furthermore, instead of studying the bulk behavior of the slurry, here the focus is given to the slurry/current collector interface in order to illustrate its importance. Hereby, it is demonstrated how this modeling tool can lead to deeper understanding and optimization of electroactive particle suspensions in redox flow batteries.

High-energy and high-power Zn–Ni flow batteries with semi-solid electrodes

“…The electronic percolation threshold for the semi-solid anolyte and catholyte was rst determined in order to design electrodes that provide sufficiently high electron-conducting pathways throughout the suspension. 39,40 The percolation threshold was dened as the critical volume fraction F c at which a sharp increase in the conductivity was observed. 41 Theoretically, below F c , only small clusters of conductive particles exist, whereas, at F c , at least one "innitely" large sample-spanning cluster of conductive particle gives rise to a sharp increase in conductivity.…”

Molecular modeling of organic redox‐active battery materials

“…Multiscale free energy calculations including explicit solvation should offer a much more robust approach to the modeling of electrochemically relevant reactions and physical processes. The atomistic simulations could be also used to parameterize mesoscopic models based on kinetic Monte Carlo simulations 138–141 . These, in turn, could be used to study the relation between OEMs’ morphology and electronic/ionic conductivity, thereby giving direct insights into the available capacity and power density.…”

Interphases in Electroactive Suspension Systems: Where Chemistry Meets Mesoscale Physics

“…However explicitly considering dynamic parameters like state of charge, particle volume, surface area, or surface functional groups that are inherent to electrochemical systems, would require simulation methods designed specifically to handle such complex phenomena at mesoscale. Mechanistic models like those based on kinetic Monte Carlo provide a suitable framework for such purposes . However application of such models is challenging because they necessitate elucidation of parameters that have not yet been measured or fully understood, and improving algorithmic efficiency through parallelization may not be straightforward if the physics to be captured by the model is to be left open to modifications.…”

“…The objective is to create a skeletal mind map with maximum possible freedom for parameter correlation . Based on this framework, a grey box kinetic Monte Carlo model was developed, which essentially hybridizes first principles and statistical mechanics methods. This allows creation of a pseudo‐topological ordering in the causal flow diagram, which is typically cyclic for complex systems .…”