Advanced Current Collector Design for High Energy Density Anode-Free Sodium-Ion Batteries

Anode-free sodium-ion batteries (AFSIBs) achieve energy storage by completely eliminating traditional anode active materials and relying solely on the reversible plating and stripping of sodium from the anode source onto the current collector surface. This approach fundamentally addresses the limitations of energy density and safety inherent in conventional sodium batteries, positioning it as a promising candidate for high-energy “super-lithium” electrochemical storage technology. However, this innovative design also places unprecedentedly stringent demands on the current collector, making it a critical component in determining cell performance. This review systematically outlines the prevailing methodologies and research progress on modifying collectors for AFSIBs, with a focus on material sodophilicity engineering and structural modulation. By comprehensively reviewing the process of different sodium-friendly material modifications, interfacial functional modulation, porous structure configuration, and gradient engineering on the cell performance, the essential elements for enhancing the electrochemical performance of the current collector are outlined. Building on this, the paper discusses the challenges and opportunities in this field and suggests new research directions for developing high-performance AFSIBs.