A systematic review of the life cycle analysis of sodium-ion batteries

Battery technologies are crucial for decarbonizing the energy system, serving various roles such as providing stationary storage to deliver renewable energy on demand and supporting mobility. Lithium-ion batteries (LIBs) are the leading technology due to their high energy density, numerous charge-discharge cycles, and low self-discharge rates. However, the extraction of lithium is geographically concentrated, with 90% of its production coming from just three countries, creating geographical risks for supply chains and dependent consumers. Similar concerns arise for other materials used in LIBs, such as Nickel, Copper, and Cobalt. In contrast, resources for the production of Sodium-Ion Batteries (SIBs) are more widely accessible, and they pose fewer safety concerns while offering better economic prospects than LIBs. Therefore, evaluating their sustainability and associated GHG emissions can guide their future design and deployment. In this systematic review of Life Cycle Assessments (LCA) of SIBs, we critically analyse existing literature on SIBs in terms of chemistry, technologies, methods, and best practices. It is found that the layered oxide chemistry is a promising alternative for a low environmental impact, with GHG emissions of 50 and 37 kg CO2-eq/kWh for the cradle-to-gate and cradle-to-grave approaches, respectively, based on the European electricity grid mix and assuming TRL 4-5. These figures represent a reduction of 8% to 25% compared to LIBs, indicating a substantial potential for emissions mitigation, which can be further enhanced by exclusively using renewable energy. Although the aforementioned values relate to the energy carriers currently in use, the application of renewable energy sources in battery production and usage is strongly recommended to achieve a low-emission life cycle. Based on this, we suggest future research directions for LCA practitioners and technology developers, emphasizing eco-design principles.