High Efficiency Acid-Base Generator for Carbon Management

Carbon dioxide capture is a critical technology for achieving carbon neutrality and mitigating the impacts of global warming. One promising approach 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.<br/>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. By optimizing the center chamber with a well-designed flow field, we achieved acid-base production at high concentrations (&gt; 1M) and high Coulombic efficiency (&gt; 94%) while maintaining relatively low energy costs (100 – 289 kJ mol⁻¹, at 20 – 200 mA cm⁻²). With this device, we have demonstrated practical carbon management in simulated flue gas capture, direct air capture, and green production of slaked lime, as one step toward green cement production.<br/>The key components of our prototype can be adapted for use in other electrochemical cell designs, ensuring high efficiency in concentrated acid-base utilization in other application scenarios. For example, management of the pH-difference and the acid-base crossover inside electrochemical systems is also crucial in pH-decoupling aqueous redox flow batteries, enabling the cell to achieve higher cell voltages and correspondingly higher energy densities, as well as supporting a broader range of redox pair combinations.