(777c) Performance and Modeling of Convection Battery

The convection battery forces flow of electrolyte through the cathode, anode, and the separator between them. The goal is to increase ion fluxes (A/cm2) to realize the benefit of thicker electrodes, lower cost batteries, and reduced charge times. A pump that circulates electrolyte was turned off to create a diffusion cell that was used as a control to which the performance of the convection battery was compared.

Based on performance at <1.1 V overpotential (based on a 3.1 V open circuit) and similar capacity utilization, the convection battery provided a 5.6 fold increase in ion flux for these initial studies, increasing flux from 1.6 A/cm2 to 8-10 A/cm2. Little capacity fade was observed on the measured discharge cycles (10 cycles). These studies provided an important milestone in the research, development, and validation of a new battery design including cycling studies with lithium iron phosphate chemistry.

A model for the convection cell is presented based on porous electrode theory. The model uses a concentrated binary electrolyte. The model was applied to a convection cell without electrolyte flow electrolyte, and a convection cell with flow of electrolyte. The different models are compared and parametric studies were performed on the convection cell to determine the effect of flow rate on the cell.