Controlling Sub-Nanometer Pore-Entrance size Enables Kinetic Separation of Li+, Na+, and K+ in Capacitive Deionization

• Carbon molecular sieve (CMS) was applied to a CDI electrode. • Kinetic separation of monovalent ion was demonstrated using the CMS-CDI system. • The adsorption rate was correlated with hydration radii and energies. • The CMS electrode exhibited high cycle stability. Efficient recovery of lithium and potassium from saline resources is vital for energy storage and global food security. We present a novel capacitive deionization (CDI) approach employing carbon molecular sieve (CMS) electrodes with precisely tuned sub-nanometer pore entrances. By leveraging chemical vapor deposition (CVD) to control entrance size, CMS enables kinetic separation of Li + , Na + , and K + – ions with nearly identical hydrated radii – through differences in hydration energy. Electrochemical analysis reveals that moderate CVD treatment dramatically suppresses Li + adsorption while preserving Na + and K + uptake, achieving unprecedented selectivity and cycle stability. This work establishes pore-entrance engineering as a transformative strategy for energy-efficient ion recovery, unlocking new pathways for sustainable lithium extraction and potassium utilization in agriculture.