Activation of MOF Catalysts with Low Steric Hindrance via Undercoordination Chemistry for Efficient Polysulfide Conversion in Lithium–Sulfur Battery

Abstract

AbstractLithium–sulfur (Li–S) batteries promise high theoretical energy density and cost‐effectiveness but grapple with challenges like the polysulfide shuttle effect and sluggish kinetics. Metal–organic framework (MOF) catalysts emerge as a leading solution, despite limited conductivity and high steric hindrance. This study employs undercoordination chemistry to modify Zn–Co bimetallic MOFs (D‐ZIF L), removing organic ligands from active centers. This process mitigates spatial hindrance, thereby promoting comprehensive contact between sulfur species and metal active centers, consequently enhancing the catalytic efficiency of MOFs. Moreover, undercoordination treatment of the metal active centers induces electron redistribution, augmenting electron density at the Fermi level of the metal elements, thereby ameliorating the intrinsic conductivity. Leveraging these advantages, fabricated Li–S batteries employing D‐ZIF L catalysts exhibited markedly mitigated shuttling effects and accelerated sulfur species conversion kinetics. Notably, a substantial reverse areal capacity of 5.0 mAh cm⁻2 is achieved after 100 cycles with an evaluated sulfur loading of 5.5 mg cm⁻2. Furthermore, a practical pouch cell demonstrated an initial capacity of 1.8 Ah at 85.8 mA with stable cycling for 50 cycles. This study underscores the potential of undercoordination chemistry in the development of highly conductive MOF catalysts with minimized steric hindrance, thereby advancing the prospects of Li–S battery technology.