The true performance of Li−CO2 batteries for resolving the disagreement on their feasibility

Lithium (Li)−CO 2 batteries, capable of converting CO 2 to Li 2 CO 3 /C while delivering significant energy, have attracted extensive research interest. However, their feasibility remains controversial and underexplored. To address this, a rigorous testing system combining ECC−Air battery models and differential electrochemical mass spectrometry (DEMS) was developed to ensure a pure gas environment. Findings reveal that even minute O 2 permeation (0.5%) from air can elevate the discharge plateau, misleadingly transforming Li−CO 2 into Li−O 2 /CO 2 batteries. Under strict testing, true Li−CO 2 battery performance falls short of reported successes. Experimental and theoretical confirmation shows the 4Li + 3CO 2 → 2Li 2 CO 3 + C reaction proceeds at a lower discharge plateau (<2.0 V), a voltage window traditionally overlooked. This work underscores the need for rigorous testing to enhance scientific reliability in Li−CO 2 battery research so that this field can develop sustainably.