Abstract
Sodium-ion batteries (SIBs) offer a promising, low-cost path for large-scale energy storage due to abundant sodium resources and favorable safety attributes. However, recycling technology for SIBs remains underdeveloped compared with lithium-ion systems, which have benefited from cobalt-driven economic incentives. This review critically examines recent research and pilot efforts in SIB recycling, emphasizing hydrometallurgical leaching and recovery of Na, Fe, Mn; direct regeneration of cathode materials; and emerging green and bio-based extraction techniques. We compare these methods with established Li-ion recycling workflows, identify technical bottlenecks (electrolyte/fluorine handling, low-value material economics, heterogeneous cathode chemistries), and evaluate industrial readiness. Finally, we outline policy and design-for-recycling recommendations, including extended producer responsibility, Na-salt integration into chemical streams, and standardized dismantling protocols that are necessary to close the loop for SIBs in a post-2030 circular economy. This perspective aims to guide hydrometallurgical research and industry planning for sustainable SIB lifecycle management.