Hard carbon is one of the most promising anode materials for sodium‐ion batteries, but the low Coulombic efficiency is still a key barrier. In this paper, a series of nanostructured hard carbon materials with controlled architectures is synthesized. Using a combination of in situ X‐ray diffraction mapping, ex situ nuclear magnetic resonance (NMR), electron paramagnetic resonance, electrochemical techniques, and simulations, an “adsorption–intercalation” mechanism is established for Na ion storage. During the initial stages of Na insertion, Na ions adsorb on the defect sites of hard carbon with a wide adsorption energy distribution, producing a sloping voltage profile. In the second stage, Na ions intercalate into graphitic layers with suitable spacing to form NaC x compounds similar to the Li ion intercalation process in graphite, producing a flat low voltage plateau. The cation intercalation with a flat voltage plateau should be enhanced and the sloping region should be avoided. Guided by this knowledge, nonporous hard carbon material has been developed which has achieved high reversible capacity and Coulombic efficiency to fulfill practical application.

A Sb/C nanocomposite was synthesized and found to deliver a reversible 3 Na storage capacity of 610 mA h g(-1), a strong rate capability at a very high current of 2000 mA g(-1) and a long-term cycling stability with 94% capacity retention over 100 cycles, offering practical feasibility as a high capacity and cycling-stable anode for room temperature Na-ion batteries.

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Sodium‐ion batteries (SIBs) are considered to be a low‐cost complement or competitor to Li‐ion batteries for large‐scale electric energy storage applications; however, their development has been less successful due to the lack of suitable host materials to enable reversible Na+ insertion reactions. Prussian blue analogs (PBAs) appear to be attractive candidates for SIB cathodes because of their open channel structure, compositional and electrochemical tunability. In this paper, the authors present a comprehensive review on the recent advances in the development of PBA frameworks as SIB cathodes with particular attention to the structure‐performance correlation of the PBA materials, and discuss the possible strategies to address the problems present in the SIB applications of PBAs. Also, the development of the PBA frameworks for the insertion cathodes of other monovalent and multivalent ions is briefly introduced, with the aim of providing a new insight into the design and development of new host materials for the next‐generation advanced batteries.