Hollow multishelled structure: A versatile platform for boosting the performance of sodium-ion batteries

Sodium-ion batteries (SIBs), with abundant resources and low cost, have established themselves as a core candidate for large-scale energy storage in the post-lithium-ion battery (LIB) era. However, electrode materials suffer from severe volume expansion, sluggish ion transport kinetics, and low energy density due to the larger radius and higher atomic weight of sodium. These challenges cannot be resolved by simply replicating LIB technologies and have thus become the core technical barriers hindering the industrialization of SIBs. Endowed with hierarchical shells, internal cavities, a large accessible surface area to volume ratio, and excellent loading capacity, hollow multishelled structure (HoMS) effectively alleviates these issues. This review systematically summarizes the design strategies and optimization mechanisms of HoMS for SIB anodes (carbon-based, alloy-type, and conversion-type materials) and cathodes (metal oxides, polyanionic compounds (PCs), and Prussian blue analogues (PBAs)), focusing on addressing key performance degradation bottlenecks. It also outlines synthesis challenges and industrialization prospects, expanding SIB electrode structural portfolios and offering actionable guidance for rational HoMS-based electrode design.