Modelling of Solid Electrolyte Interface (SEI) layer of lithium-ion batteries using kinetic Monte Carlo approach

The accurate model on the growth of Solid-Electrolyte Interface (SEI) layer of Lithium-ion batteries is useful to study the capacity fade, ageing, and cycling life, and provides significant information to ensure the battery safety. The model for SEI layer dynamics is based on the Kinetic Monte Carlo approach, in which four major dynamical processes of adsorption, absorption, diffusion, and passivation are described by their individual rates, determined from chemical and physical properties of materials used in the battery. Total cycle numbers to be simulated determined the number of Kinetic Monte Carlo steps. The formation of a passive SEI layer with variable thickness is simulated based on the mathematical model of SEI dynamics. For every cycle, with the update of coverage and the thickness, the interfacial resistance is calculated. The simulation results are found consistent with literature where thickness increases as proportional to the square root of the time (cycle). The interfacial resistance obtained from the simulation is used in 1D-electrochemical model, to predict the charge-discharge behavior of the battery with varying resistance. After the coupling of SEI layer model to the 1-D electrochemical model, the results obtained from the simulation will be validated with the experimental results.