Host–Guest Synergy of COF and CoO Enables In Situ Oxygen Vacancies and Regulated Li + Behavior for High‐Performance Anode‑Free/Less Li Metal Batteries

ABSTRACT Anode‐free Li metal batteries (AFLMBs) are excellent candidates for electric vehicles and low‐altitude aircrafts because of their high energy density. However, the industrialization of AFLMBs remains limited by the poor reversibility of Li + deposition and stripping on Cu current collectors (CCs). In this study, a composite CC (TCMS@Cu) integrating a covalent organic framework (COF) membrane and CoO nanoparticles is constructed to address these challenges. The TCMS@Cu forms a dense COF crystalline membrane on Cu foil via epitaxial growth and incorporates lithiophilic CoO nanoparticles. The host–guest synergistic effect between the COF and CoO effectively guides Li + migration into COF cavities, effectively suppressing dendrite formation and the accumulation of inactive Li. During the initial deposition process, CoO reacts with Li + to generate oxygen vacancies, further enhancing the performance of the TCMS membrane. The anode‐less Li metal batteries (ALLMBs) assembled with LiFePO 4 cathode achieve an exceptional cycle life of 850 cycles and a high‐rate capacity retention of 94.4% at 5C. The assembled AFLMB pouch cells deliver energy densities of 288 Wh kg −1 (LFP|CC) and 452 Wh kg −1 (NCM811|CC) (calculated without cell can and tabs). This work provides an effective strategy for designing high performance AFLMBs and promotes the development of next‐generation energy storage devices.