Electrochemical acid-base generators for decoupled carbon management

Abstract

Carbon dioxide capture and management are critical technologies for achieving carbon neutrality and mitigating the impacts of global warming. One promising approach for decarbonization involves electrochemical generation of concentrated acid and base. This effectively decouples the carbon capture-release process from the electrochemical cell, avoiding the kinetic limitations associated with reactions involving CO2. Designing an electrochemical acid-base generator with high current efficiency and low energy cost is challenging. Following investigations of the crossover rates of protons and hydroxide ions through ion-exchange membranes, we designed a multichambered electrochemical cell for generating weak acid and strong base, which significantly suppressed acid-base crossover. By equipping the center chamber with a serpentine flow field, we achieved acid-base production at high concentrations (> 1 M) and high Coulombic efficiency (> 95%) while maintaining relatively low energy costs. With this device, we demonstrated carbon management examples of simulated flue gas capture, direct air capture, and green production of slaked lime, as one step toward green cement production. The key components of the prototype can be adapted for use in other electrochemical cell designs, ensuring high efficiency in concentrated acid-base generation in other application scenarios.