Self‐Confinement Effect Enabled by Hollow Carbon Nanoreactor for High‐Performance Li–Cl ₂ Battery

Rechargeable Li─Cl 2 batteries represent a promising high‐energy‐density technology. However, the open‐pore structure of conventional cathode materials poses a fundamental challenge by permitting the uncontrolled diffusion of Cl 2 into the electrolyte, resulting in severe local concentration dilution that plagues rate capability and specific capacity. Herein, a self‐confinement strategy by hollow carbon nanoreactors (HCNRs) is proposed to regulate the local concentration of active Cl 2 species with micropores (≈0.8 nm) on their walls. These micropores act as size‐selective barriers, allowing to block the escape of larger active Cl 2 species (kinetic diameter ≈0.86 nm), and mesopores (30–50 nm) function as nanoreactors that concentrate active Cl 2 species. This design enables the as‐assembled Li─Cl 2 cell to achieve an ultrahigh current density of 100 mA cm −2 during the charge/discharge process and a record‐breaking specific capacity of 8000 mAh g −1 (9 mAh cm −2 ), superior to the reported literature. This hollow nanoreactor design highlights the potential of Li─Cl 2 batteries as high‐power and energy‐dense systems, paving the way for their practical application.