Discharge Performance Dependence on Electrode Thickness for Li4Ti5O12/LiMn2O4 Cells for Application in Wafer-Integrated Microbatteries

Abstract

Rechargeable lithium-ion microbatteries are attracting attention for application in self-sufficient microelectronic systems. However, energy densities need to be improved. Introduction of thicker electrodes would increases the energy density. Thus, discharge performance investigations on Li4Ti5O12(s)|LiPF6(sol.)|LiMn2O4(s) pouch-cells containing electrodes with 0.95, 1.90, 2.85, 3.80, and 4.75 mAh cm-2 loading were done. The results showed that for lower current densities (< 13 mA cm-2) the thicker electrodes generate a higher discharged capacity. On the other hand, as the current density rises, the discharged capacity seems to become almost independent of the electrode thickness. This maximum capacity retention might be related to the polarization in the electrolyte and electrodes upon discharging. Based on the Newman model for micro porous electrodes, simulation of the battery discharge characteristics has been done with help of the simulation software COMSOL multiphysics.