In this study, the performance of semi-solid electrodes for flexible lithium-ion batteries (LIBs) is investigated. The semi-solid electrodes are composed of the electrodes’ active and conductive additive materials that are suspended in liquid electrolyte. Flexible Li-ion batteries (LIBs) have a strong oncoming consumer market demand for use in wearable electronic devices, flexible smart electronics, roll-up displays, electronic shelf labels, active radio-frequency identification tags, and implantable medical devices. This market demand necessitates research and development of flexible LIBs in order to fulfill the power requirements of these next-generation devices. In this study, the performance of semi solid anode for flexible Lithium-ion battery is investigated through mathematical modeling and computer simulation in order to reduce the number of experiments and to achieve the desired energy density of the battery. This model is a multiphysics three-dimensional heterogeneous model, where all necessary transport phenomena including the charge and mass transfer and electrochemical reactions are considered at continuum mechanics level. The COMSOL Multiphysics software is used to solve governing equations numerically using the finite element method (FEM). This model is made for a half-cell simulation, and validated by experimental results obtained in lab. The maximum discharge specific capacity of the simulated Graphite half-cell and lithium cobalt oxide (LCO) have reached 248 (mAh/g) and 128 (mAh/g), respectively, in the computer simulation, while the values achieved by the experimental tests are 240 (mAh/g) for the graphite half-cell and 120 (mAh/g) for the LCO half-cell, respectively. This shows the simulation results are in acceptable agreement with the experiment. In fact, the simulation results are in agreement with experiment results with an error of 3% at the end of discharge for the anode (graphite) half-cell, and less than 8% for the cathode (LCO) half-cell. After validation, a parametric study is conducted through which the effects temperature, charge / discharge rates and volume fraction of electrodes active materials on the performance of graphite and LCO half cells are investigated. It is shown that how the specific discharge capacity of half-cells are increased with increasing temperature due to the faster electrochemical reactions and lower ohm resistance at higher temperatures. It is also shown that when the cell is discharged at a higher c-rate, how the reaction rate at the electrode particle surface leading to lower capacity at the end of discharge. Several other effects are also presented and discussed in this paper.Keywords: lithium-ion battery; Semi-solid electrode; full 3D mathematical modeling; Heterogamous modeling; electrochemical performance; Parametric study.

Mathematical Modelling of Semi-Solid Electrodes for Flexible Lithium-Ion Batteries

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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