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

Lithium (Li)-CO₂ batteries, capable of converting CO₂ to Li₂CO₃/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 O₂ permeation (0.5%) from air can elevate the discharge plateau, misleadingly transforming Li-CO₂ into Li-O₂/CO₂ batteries. Under strict testing, true Li-CO₂ battery performance falls short of reported successes. Experimental and theoretical confirmation shows the 4Li + 3CO₂ → 2Li₂CO₃ + 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-CO₂ battery research so that this field can develop sustainably.