Enhanced Electrochemical CO 2 Capture Through Galvanostatic Protocol Optimization of MnO 2 ‐Based Proton Intercalation Systems

ABSTRACT Electrochemically‐driven CO 2 capture via aqueous proton intercalation offers a compelling route to low‐energy CO 2 separations, but development of this chemistry to‐date has been hindered by operation at low current densities and rapid electrode degradation. This work demonstrates that the use of certain electrochemical cycling protocols can improve the performance and energy‐efficiency of proton‐intercalation materials (specifically, manganese oxide, MnO 2 ) in aqueous CO 2 capture applications, and that untuned electrochemical cycling protocols can drive MnO 2 electrodes into damaging voltage and over‐discharge regimes. We demonstrate that charge‐limited cycling protocols reduce the rate of capacity fade and mitigate dissolution failure modes in MnO 2 , increasing the stability of our unmodified, binder‐less MnO 2 electrodes to >98% capacity retention over 60 capture‐release cycles, and doubling CO 2 throughput over prior bench‐scale demonstrations. Our optimized cycling conditions also reduce the electrical energy requirements of electrochemical CO 2 capture to values as low as 28 kJ e mol −1 CO 2 (non‐concentrating), approaching the theoretical minimums for this system. Overall, this work sets a new experimental benchmark for MnO 2 intercalation‐based electrochemical capture and highlights how process optimizations from the energy‐storage field can be adapted to improve electrochemical CO 2 capture methods.