Modeling Slurry Electrodes for Redox Flow Batteries Using Kinetic Monte Carlo

Abstract

A new technological avenue, that allows utilization of conventional rechargeable battery material at grid scale, has opened up with the development of slurry redox flow batteries (SRFBs) [1]. These can offer volumetric capacity of up to 5-20 times greater than conventional redox flow batteries based on aqueous solutions [1]. However optimization and commercialization of SRFBs requires better understanding of suspension stability, non-Newtonian fluid flow behavior, electrochemical cycling phenomena, and consequent particle dynamics of the solid material in suspension. In this work we present a multiphysics mesoscopic modeling tool resolved using an kinetic Monte Carlo algorithm [2,3] in three dimensions. This model simulates the phenomena which take place during the discharge of a SRFB in static mode with a silicon-carbon based slurry in organic electrolyte [4]. It captures the dynamics of electronic percolation networks of carbon particles created during Brownian motion. These percolation networks form electron conduction pathways for silicon particles to discharge and eventually undergo volume expansion [Fig.1]. Results are discussed in contrast to in-house experimental data [4]. Our model offers a first look into the complex interplay of intrinsic parameters that need to be understood to achieve optimization based on factors like carbon volume fractions and C-rates [5]. Fig. 1. Snapshot of the channel during galvanostatic discharge slurry containing carbon (in red) and silicon particles (in blue). When silicon is in contact with carbon percolation networks (in yellow), it can discharge. The channel thickness is 1.5 μm and the area of the current collector is 6.25 μm2. References : [1] M. Duduta, B. Ho, V. C. Wood, P. Limthongkul, V. E. Brunini, W. C. Carter, and Y. Chiang, Adv. Energy Mater., 1(2011) 511 [2] M. A. Quiroga, and A. A. Franco, J. Electrochem Soc. 161(7) (2015) E73. [3] G. Blanquer, Y. Yin, M. A. Quiroga, and A. A. Franco, J. Electrochem Soc., 163(3) (2016) A329 [4] S. Hamelet, D. Larcher, L. Duport, and J. M. Tarascon, J. Electrochem Soc., 160(3) (2013) A516. [5] G.Shukla, D. del Olmo Diaz, V. Thangavel, and A. A. Franco, in preparation (2016) Figure 1