Dual-Function Electrochemical Cell for Simultaneous Carbon Capture and Lithium Extraction from Saline Waters

Abstract

Effective utilization of saline waters as a large reservoir of both dissolved inorganic carbon (DIC) and lithium would simultaneously support carbon mitigation and secure critical mineral supply. Here, we report the first demonstration of a dual-function electrochemical system capable of coupling CO2 capture and Li⁺ extraction from saline waters. Using a pH-swing architecture with bismuth and LiFePO₄ electrodes, we achieve stable pH cycling between 8.1 and 4.7 in 2.1 mM DIC, while extracting lithium at concentrations down to 0.17 ppm Li⁺ (seawater levels). Under impurity-free conditions, the system maintains 80% bismuth utilization and 50% lithium utilization, with attractive energetic costs of 128 kJ mol⁻¹ CO2 and 121 kJ mol⁻¹ Li, comparable to state-of-the-art stand-alone electrochemical systems. By integrating Li⁺ and CO2 extraction using shared pumping, membrane, and reactor infrastructure, this system offers a compelling path toward co-production of critical materials and integrated CO2 capture using a single seawater-processing platform.