Organocatalytic Lithium Chloride Oxidation by Covalent Organic Frameworks for Rechargeable Lithium-Chlorine Batteries

Rechargeable Li-Cl₂ battery is a promising high energy density battery system. However, reasonable cycle life could only be achieved under low specific capacities due to the sluggish oxidation of LiCl to Cl₂ . Herein, we propose an amine-functionalized covalent organic framework (COF) with catalytic activity, namely COF-NH₂ , that significantly decreases the oxidation barrier of LiCl and accelerates the oxidation kinetics of LiCl in Li-Cl₂ cell. The resulting Li-Cl₂ cell using COF-NH₂ (Li-Cl₂ @COF-NH₂ ) simultaneously exhibits low overpotential, ultrahigh discharge capacity up to 3500 mAh/g and a promoted utilization ratio of deposited LiCl at the first cycle (UR-LiCl) of 81.4 %, which is one of the highest reported values to date. Furthermore, the Li-Cl₂ @COF-NH₂ cell could be stably cycled for over 200 cycles when operating at a capacity of 2000 mAh/g at -20 °C with a Coulombic efficiency (CE) of ≈100 % and a discharge plateau of 3.5 V. Our superior Li-Cl₂ batteries enabled by organocatalyst enlighten an arena towards high-energy storage applications.