Freeze-Dried Low-Curvature Porous Structure Iron Phosphate Electrodes for Efficient Lithium Extraction from Brine

Abstract

This study demonstrates the fabrication of high-loading lithium iron phosphate electrodes with a low-curvature porous structure via a freeze-drying method (FD-LFP) and investigates the differences in electrochemical performance and lithium extraction applications compared to electrodes prepared using a conventional heat-drying method (HD-LFP). The results indicate that the FD-LFP electrode surface exhibits a low-curvature porous structure, which increases the effective surface area of the electrode material, providing more active sites for electrochemical reactions and thereby enhancing lithium storage capacity. Additionally, this pore structure demonstrates excellent connectivity, effectively reducing lithium ion accumulation and blockage on the electrode surface, thus improving ion transport efficiency. Furthermore, it strengthens the interaction between the electrode material and the current collector, preventing detachment of the electrode material.Utilizing the freeze-drying method, FD-LFP electrodes with graphite-coated paper as the current collector (FD-LFP-GCP) exhibited superior performance. The FD-LFP-GCP//AC electrodes were evaluated for lithium extraction from simulated brine in the Atacama salt lake, showing an energy consumption of 0.422 Wh / mol, a lithium extraction capacity of 40.45 mg / g, a lithium extraction areal capacity of 0.906 mg / cm2, and a lithium ion purity of 92.04 %. The low-curvature porous structure electrode provides more active sites, enhancing lithium storage capacity per unit electrode area, thus offering significant potential for the widespread application of electrochemical lithium extraction technology.

Keywords: Electrochemical lithium extraction, High-loading, porous structure, Freeze-drying method