A novel approach to prevent the CO2 shuttle corrosion in Li-CO2 battery by a separator gas barrier design

Lithium carbon dioxide (Li-CO 2 ) batteries exhibit an ultrahigh theoretical energy density of 1876 Wh∙kg −1 and enable potential CO 2 capture for carbon neutrality. However, acidic CO 2 reacts with Li-metal anodes (CO 2 shuttle effect), causing pulverization and battery failure. Herein, we propose a separator gas barrier design strategy to address the critical issue of CO 2 shuttle-induced corrosion in Li- CO 2 batteries. The core of this strategy lies in a diamond-like carbon (DLC)-modified separator, which is engineered to possess exceptional gas barrier properties. Theoretical calculations and systematic experimental verifications collectively confirm that this separator efficiently suppresses the CO 2 shuttle effect, fundamentally mitigating Li-anode corrosion. Notably, the Li-CO 2 battery with this separator achieves a long cycle life over 1200 h (500 mAh∙g −1 , no extrinsic metal-based catalyst)—over 5 times longer than that with a pristine separator (240 h). This work provides a novel, universal design paradigm to enhance the cycling stability of metal-gas batteries (e.g., Li-O 2 , Na-CO 2 ), addressing a long-standing challenge in high-performance metal-gas energy storage systems by using separators as “gas barriers” to protect metal anodes.