Critical Advances in Seawater Battery Technology: From System Architecture to Anode Materials

This review critically examines seawater batteries (SWBs) as an innovative solution to overcome the limitations of conventional lithium-ion batteries (LIBs). As the global transition toward sustainable energy systems accelerates, fundamental vulnerabilities of LIBs—including resource scarcity, thermal safety concerns, and environmental degradation—have become increasingly apparent. SWBs emerge as a promising alternative by utilizing abundant sodium ions in seawater, effectively avoiding resource-intensive mining while providing inherent thermal management capabilities. The review systematically analyzes the evolution of SWB technology, focusing particularly on recent developments in anode materials across three distinct categories: hard carbon-based intercalation materials, alloy-based compounds, and conversion reaction materials. It elucidates how strategic material design approaches, including structural modifications, heteroatom doping, and hybrid composites, effectively address critical challenges such as capacity fading and volume expansion. The integration of sustainable precursors, exemplified by biomass-derived carbons, maintains high electrochemical performance while meeting environmental imperatives. Additionally, significant advances in electrolyte formulations and cell architecture demonstrate their collective contribution to system efficiency and scalability. While several challenges persist, including interface stability optimization and marine corrosion mitigation, SWBs present a promising pathway toward large-scale energy storage systems through their unique combination of abundant resources, inherent safety features, and advancing material technologies.