Modeling and Simulation of All-Solid-State Batteries with Polymer Electrolytes

Kurzfassung

All-solid-state batteries (ASSB) are experiencing a growing scientific interest in recent years as potential next-generation high-voltage batteries with great intrinsic safety. Polymer electrolytes could provide a pathway to solid-state Li-metal batteries by solving current problems such as dendrite growth and flammability . Especially the mechanical properties and stability make polymer electrolytes promising candidates, as shown by the large number of different polymers being discussed. In this contribution, we derive a continuum transport model for charge and mass transport in polymer electrolytes and compare the results for two different polymer electrolytes. The methodological framework for our thermodynamically consistent multi-physics approach is given in previous work. The description of the material behaviour is given by the choice of the specific free energy, to which we include contributions from mechanical deformation, configurational entropy, and electric fields. The mechanics is described by the Ogden model for compressible rubber-like materials, while the Flory-Huggins solution model catches the entropic behaviour of the polymer solution. In contrast to other models, we formulate our transport theory with respect to the polymer reference system. This more intuitive approach enables an easier parametrization with data from atomic scale simulations, e.g. molecular dynamics simulations. We apply this transport model to the archetypical polymer electrolyte of Polyethylene glycole (PEO) with a Li salt and to a single-ion conducting block copolymer electrolyte . The comparison of these two different electrolytes demonstrates that our model can reproduce a wide variety of different polymer classes. This transport model serves as a first step towards the theory-based spatially and time-resolved description of processes in ASSBs with polymer electrolytes.