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

Abstract

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.