A solid-electrolyte-interface (SEI) layer that grows at the electrode surface is a vital factor to predict calendar-life time and cycling performance of lithium-ion batteries. This thesis intends to develop a model that couples detailed chemistry and multi-species transport with a stress evolution process in the SEI, and make an uncertainty quantification of relative parameters. Electrochemical and mechanical equations are derived and solved, and a global uncertainty analysis method with polynomial chaos (PC) expansions is developed. Particularly, transport equations involve species and charge conversation with a constraint of electroneutrality. The coupling model focuses on the stress evolution in the SEI layer from 0.1C to 1C.

The kinetic parameters are quantified by variance...[ Read more ]

A solid-electrolyte-interface (SEI) layer that grows at the electrode surface is a vital factor to predict calendar-life time and cycling performance of lithium-ion batteries. This thesis intends to develop a model that couples detailed chemistry and multi-species transport with a stress evolution process in the SEI, and make an uncertainty quantification of relative parameters. Electrochemical and mechanical equations are derived and solved, and a global uncertainty analysis method with polynomial chaos (PC) expansions is developed. Particularly, transport equations involve species and charge conversation with a constraint of electroneutrality. The coupling model focuses on the stress evolution in the SEI layer from 0.1C to 1C.

The kinetic parameters are quantified by variance-based method, and the numerical integral method is employed by Smolyak’s cubature. Compared with prior models, this model which starts from a valid 1 nm thickness provides an advanced understanding of electrochemical properties of charged species in the SEI layer, and couples with mechanical aspects. This coupling model gives a first description of the diffusion-induced stress generation in the SEI, where the tangential components mainly affect the mechanical properties with a value above 100 MPa. After uncertainty quantification, we figure out the electron charge transfer reaction mainly control the growth process and the stress generation process according to its highest uncertainty.