Comprehensive assessment of carbon emissions and environmental impacts of sodium-ion batteries and lithium-ion batteries at the manufacturing stage

Under the background of carbon neutrality, automobile electrification has become an international consensus, and zero carbon throughout the life cycle of the automobile industry chain is an urgent task. Sodium-ion batteries (SIBs), a valuable supplement to lithium-ion batteries (LIBs), have attracted global attention due to their low price and rich raw materials. However, few studies have compared and evaluated the environmental indicators of SIBs and LIBs. Here, the carbon emissions and various environmental indicators of five LIBs and six SIBs at the manufacturing stage are calculated and compared utilizing the life-cycle assessment method in various scenarios. Our findings indicate that: (1) The most environmental indicators of SIBs are generally lower than those of LIBs, and the carbon emissions of the two types of battery demonstrate different distributions. (2) The carbon emission from the production of cathode material for LIBs accounts for the highest proportion of total carbon emission during battery production (over 50%), and that for SIBs exhibit diversity. (3) Carbon emissions are intensely associated with the electricity mix. The cleaner the electricity mix, the lower the carbon emissions of the battery production, and the more significant the gap between SIBs and LIBs. (4) As the proportion of renewable energy generation in China's future electricity mix continuously escalates, a progressive decline appears in carbon emissions, and the advantages of SIBs in carbon emissions have a prominent growth during battery production. This study provides a valuable reference for reducing the environmental impacts during the manufacturing stage of SIBs and LIBs in different material systems.