Co Single-Atom Catalysis for High-Efficiency LiCl/Cl2 Conversion in Rechargeable Lithium-Chlorine Batteries.

Lithium-chlorine (Li-Cl2) secondary batteries are emerging as promising candidates for high-energy-density power sources and an extensive operational temperature range. However, conventional electrode materials suffer from weak adsorption for chlorine gas (Cl2) and low conversion efficiency of lithium chloride (LiCl), leading to significant loss of chlorine-based active materials. This issue hampers the cyclability of Li-Cl2 batteries. In this work, it is demonstrated that synergistic Cl2 adsorption on the electrode surface and the energy barrier for LiCl reactions are crucial for enhancing Cl2/LiCl conversion efficiency. Consequently, a cobalt (Co) single-atom site catalyst with a Co-N4 coordination environment has been developed, which significantly diminishes the transformation barrier of solid LiCl particles into Cl2 and concurrently enhances the chemical adsorption of Cl2, facilitating uniform nucleation of LiCl. As a result, the Li-Cl2@Co-NC battery developed has achieved a 0.6 V reduction in polarization voltage under high current densities, effectively addressing the issue of low conversion efficiency between Cl2 and LiCl. At room temperature, the Li-Cl2@Co-NC battery achieves over 600 cycles at 1500 mA g-1; At -40 °C, it reaches 650 cycles at 500 mA g-1. The research overcomes the cycle stability barrier in high-current Li-Cl2 batteries and offers a strategy for batteries with a wide temperature range and long cycle life.