Monte Carlo or Stochastic Electrode Structure Model

4 Monte Carlo or Stochastic Electrode Structure Model 

A third distinct type of electrode model developed in response to the need for modelling the composite structure of SOFC electrodes more accurately is the Monte Carlo, or stochastic structure, model. This model is based on a random number-generated 2- or 3-D structure of electrode particles, electrolyte particles, and holes (for gas pores). It has been shown to represent the composite conductivity quite well and may be able to model polarisation behaviour adequately [56-58]. This is of Interest because microstructure, and in particular hard-to-control variations in local microstructure, may have an important effect on overall polarisation, perhaps more so than the intrinsic kinetic characteristics measured at an ideal interface. 

The Monte Carlo-type electrode model is also called the particle connectivity model because its physics is straightforwardly based on KirchhofTs law for an electrical network, with particle resistance and interconnection resistances defined by a set of rules to mimic the current flow and electrochemical current generation within the microstructure. The electrochemical process is considered to take place with a constant resistance in agreement with intuitive notions about the mechanism. Variants of this concept attach correlated values to the resistances in the network to model polarisation more closely according to a percolation concept of active sites and passive connections [59]. Other specialised types of electrode models are mentioned briefly below, 

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