(378al) A Macroscopic Model Accounting for the Composite Effects for an Ion Lithium Cell with a LiFePO4 Cathode

The increasing energy demand and actuals pollution problems derived from fossil fuels require the generation of energy by renewable sources, and energy storage devices to solve the intermittency problems. Li-ion batteries have been positioned as one of the best storage devices recently in electric vehicles and have the possibility to implement as large energy storage [1]. A typical Ion-Lithium cell is formed for two electrodes (anode and cathode), one separator to avoid the contact between them, and an electrolytic solution containing dissociated salts for enable ion transfer between two electrodes [1-3].

The electrodes are porous structures composed by the mixture of the active material and additional compounds that improve the transport properties of charge and mass; however, it is paramount to account for numerous problems related to transport mechanisms of charge and mass that significantly affect its capacity and power [4]. The understanding of these mechanisms is complex due to various kinetic and transport phenomena interacting within the cell, and the difficulty of predicting local variables such as concentration, potential, among others. Mathematical modelling is a tool normally used to understand and decouple this interaction [5-10].

On other hands, the composition of the cathode slurry has, recently, been reported to influence battery performance and rate capability [10]. In order to understand the battery behaviour, the relation of Li⁺ diffusion with cathode composition and operation conditions (C-rate and state of discharge), in this work, we propose a pseudo-heterogeneous model for the description of the electrochemical behaviour of a half cell configuration of Li°/1M LiPF₆ in 1:1:1 CE: DMC:EMC/LiFePO₄:PVDF-Csp. This model accounts for the main transport phenomena involved in the cell (diffusion and migration) and the intercalation kinetics of Li⁺ ion in the active material from electrode. This model is used to analyse the influence of operation conditions in the transport and kinetic mechanisms during the cell operation.

References

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Acknowledgements

I.O. Santos Mendoza thanks to CONACYT for the scholarship granted to pursue her doctoral studies and Universidad Autónoma Metropolitana for the support.