ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

Spatially resolved modelling of (de-)intercalation in Li-Ion battery materials (SP4)

Charging and discharging processes in lithium ion batteries are connected with intercalation and deintercalation of lithium into/ from the electrode material. While (de-)intercalation is in progress, voltage change, phase transformation, mechanical loading and plastic deformation can occur, depending on the chosen electrode material. With phase diagrams of the materials at hand, it is possible to model the phase transformations within the battery system using the OpenPhase simulation framework developed at the STKS department. It offers also the basic set of tools to include modelling of e.g. composition transport and elastic deformation.

Simulation result: A FePO4 electrode particle fixed at a inert layer is intercalated by lithium from the surrounding electrolyte (left figure); during the intercalation the pressure within the particle rises, especially at the top part (right figure)

Within this project, the available calculation schemes are expanded by an electrostatic solver to take the electrical driving force acting on the lithium ions into account. Also, the mechanical approach is coupled with the solution of the composition distribution to allow composition dependent mechanical variables resulting in additional material fluxes and a realistic stress field. Together with a plasticity model (in collaboration with the MMM department), a complete picture of the electrode (dis-)charging process shall be developed allowing material failure analysis and the possibility of optimization of structure and chemical composition.

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