biostudies-literatureUnknown28(12)Chen KLithium (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 + iScience114047https://www.ebi.ac.uk/biostudies/studies/S-EPMC12686804biostudies-literatureThe true performance of Li-CO<sub>2</sub> batteries for resolving the disagreement on their feasibility.PMC12686804Chen KHuang GFan YQYang DYZhang HRLi KDu JYWang JfalseThe true performance of Li-CO<sub>2</sub> 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 + 2025-01-01T00:00:00Z2025 Dec2026-06-06T00:13:23.39Z2026-05-23T03:14:03.004ZS-EPMC126868044137765510.1016/j.isci.2025.114047