Virtual electrode design of thick Li-Ion batteries

Abstract

Li-Ion batteries are commonly used in portable electronic devices due to their outstanding energy and power density. A remaining issue which hinders the breakthrough e.g. in the automotive sector is the high production cost. Going ‘giga’ is one approach currently pursued but requires large investments. Recently, battery concepts with thick electrodes were presented as attractive alternative1. Batteries with thicker electrodes provide higher theoretical energy densities with only a few electrode layers which reduces production time and cost2. In our contribution we present 3D micro-structure resolved simulations of thick (electrodes > 300µm) Graphite-NMC batteries based on our thermodynamically consistent simulation framework BEST3. The parametrization and validation of our model is presented in a recent publication4 and simulation results agree favourably with experimental data2. As a major problem we identified transport limitations in the electrolyte at comparatively small C-rates2,4. Novel design and operation strategies of the battery and its components are needed to mitigate this issue. In this presentation we will focus on our on-going electrode design studies. Two different design concepts using laser perforation and/or porosity gradients were evaluated regarding their performance at high C-rates. Therefore, multiple realizations of electrode structures were generated with a stochastic 3D geometry generator5. The structures and corresponding electrochemical simulations were validated against tomography and experimental data of model electrodes. The virtual screening of different configurations provides material-structure-function relationships which are a helpful tool for the processing of thick electrodes on larger scales. 1. Hopkins, B. J. et al, Component-cost and performance based comparison of flow and static batteries. J. Power Sources 293, 1032–1038 (2015). 2. Singh, M. et al, Thick Electrodes for High Energy Lithium Ion Batteries. J. Electrochem. Soc. 162, A1196–A1201 (2015). 3. Latz, A. et al, Multiscale modeling of lithium ion batteries: thermal aspects. Beilstein J. Nanotechnol. 6, 987–1007 (2015). 4. Danner, T. et al. Thick electrodes for Li-ion batteries: A model based analysis. J. Power Sources 334, 191–201 (2016). 5. Westhoff, D. et al. Parametric stochastic 3D model for the microstructure of anodes in lithium-ion power cells. Comput. Mater. Sci. 126, 453–467 (2017).