Comprehensive Understanding of Closed Pores in Hard Carbon Anode for High-Energy Sodium-Ion Batteries

• This review establishes a unified conceptual framework for closed pores in hard carbon anodes, clarifying their origin and structural characteristics. • It systematically correlates closed pore features with sodium storage behavior, proposing design principles for directional pore regulation. • Advanced modification strategies integrating molecular-level design and kinetic/thermodynamic analyses are highlighted for performance optimization. • The insights aim to accelerate commercialization of hard carbon anodes for high-energy-density sodium-ion batteries.