To promote the transition of the transportation system towards a cleaner mode, battery electric vehicles (BEVs) have emerged as a trend in the automotive industry worldwide owing to their greater carbon reduction potential. However, an often−overlooked crucial fact is that BEVs yield higher carbon emissions during the production phase compared to internal combustion engine vehicles (ICEVs), primarily attributed to the carbon emissions generated by the core component − the battery. This results in a delayed carbon reduction benefit in BEVs, requiring a longer period of use to offset. This study employs the Life Cycle Assessment (LCA) to delve into the carbon emission risks of batteries. Firstly, this study systematically evaluates the carbon emissions of NCM and LFP batteries throughout the entire process, including raw material acquisition and processing, battery manufacturing, battery usage, and end−of−life treatment. Secondly, the study explores the delayed emission reduction benefits of BEVs resulting from the carbon emissions of batteries, indicating that it takes at least 3.6 years (NCM batteries) and 2.8 years (LFP batteries) of usage for the carbon emissions to be offset. Therefore, this study posits that the carbon emission risks of batteries in China primarily manifest in their significant carbon emissions and extended time required for carbon offsetting. Lastly, the study proposes strategies to address the carbon emission risks from three aspects: establishing a carbon accounting system, promoting standardized development in the recycling industry, and optimizing the structure of electric power systems.