Over the past decades, ground‐breaking techniques and transformative progress have been achieved on exploring alternative battery candidates beyond lithium‐ion batteries, among which sodium‐/potassium‐ion batteries (SIBs/PIBs) are receiving rapidly increased attention. Great efforts have been devoted to developing verified anode materials. Carbon materials take the leading position because of their abundance, low‐cost, environmental friendless, and commercial potential. While it is easy to understand which specific carbon material exhibits outstanding performance, the understanding of electrochemical reaction mechanisms, the structure–performance relation, and the interfacial properties of carbon anodes are rather difficult. It is urgently required to comprehensively summarize and further compare these fundamental issues, but it is still insufficient. This review concentrates on recent progress of carbon materials for SIBs and PIBs, and at the beginning summarizes the fabrication and characterization of different carbon allotropes, then fundamentally compares the ion storage mechanisms and interfacial chemistries. Furthermore, the relationship between the mechanism‐oriented and interface‐correlated performance and material optimization strategies is established. Finally, critical challenges and future developments of carbon anodes for the practical realization of SIBs/PIBs are proposed. This review gives a comprehensive summary and perspective from mechanisms to material design, offering a reliable guidance of carbon materials for SIBs and PIBs.

Constructing a homogenous and inorganic‐rich solid electrolyte interface (SEI) can efficiently improve the overall sodium‐storage performance of hard carbon (HC) anodes. However, the thick and heterogenous SEI derived from conventional ester electrolytes fails to meet the above requirements. Herein, an innovative interfacial catalysis mechanism is proposed to design a favorable SEI in ester electrolytes by reconstructing the surface functionality of HC, of which abundant CO (carbonyl) bonds are accurately and homogenously implanted. The CO (carbonyl) bonds act as active centers that controllably catalyze the preferential reduction of salts and directionally guide SEI growth to form a homogenous, layered, and inorganic‐rich SEI. Therefore, excessive solvent decomposition is suppressed, and the interfacial Na+ transfer and structural stability of SEI on HC anodes are greatly promoted, contributing to a comprehensive enhancement in sodium‐storage performance. The optimal anodes exhibit an outstanding reversible capacity (379.6 mAh g−1), an ultrahigh initial Coulombic efficiency (93.2%), a largely improved rate capability, and an extremely stable cycling performance with a capacity decay rate of 0.0018% for 10 000 cycles at 5 A g−1. This work provides novel insights into smart regulation of interface chemistry to realize high‐performance HC anodes for sodium storage.

The powerful and rapid development of lithium‐ion batteries (LIBs) in secondary batteries field makes lithium resources in short supply, leading to rising battery costs. Under the circumstances, sodium‐ion batteries (SIBs) with low cost, inexhaustible sodium reserves, and analogous work principle to LIBs, have evolved as one of the most anticipated candidates for large‐scale energy storage devices. Thereinto, the applicable electrode is a core element for the smooth development of SIBs. Among various anode materials, metal selenides (MSex) with relatively high theoretical capacity and unique structures have aroused extensive interest. Regrettably, MSex suffers from large volume expansion and unwished side reactions, which result in poor electrochemistry performance. Thus, strategies such as carbon modification, structural design, voltage control as well as electrolyte and binder optimization are adopted to alleviate these issues. In this review, the synthesis methods and main reaction mechanisms of MSex are systematically summarized. Meanwhile, the major challenges of MSex and the corresponding available strategies are proposed. Furthermore, the recent research progress on layered and nonlayered MSex for application in SIBs is presented and discussed in detail. Finally, the future development focuses of MSex in the field of rechargeable ion batteries are highlighted.

Hard carbon (HC) has attracted extensive attention due to its rich material source, environmental non-toxicity, superior sodium storage capacity, and lower sodium storage potential, and is considered most likely to be a commercial anode material for sodium-ion batteries (SIBs). Nevertheless, the limited initial Coulombic efficiency (ICE) of HC is the main bottleneck hindering its practical application. To alleviate this issue, herein, a ZrO2 coating was skillfully constructed by using a facile liquid phase coating method. The ZrO2 coating can act as a physical barrier to prevent direct contact between the HC surface and the electrolyte, thus effectively reducing irreversible sodium adsorption and inhibiting the continuous decomposition of the electrolyte. Meanwhile, this fresh interface can contribute to the generation of a thinner solid electrolyte interface (SEI) with high ionic conductivity. As a result, the ICE of the ZrO2-coated HC electrode can be optimized up to 79.2% (64.4% for pristine HC). Furthermore, the ZrO2-coated HC electrode delivers outstanding cyclic stability so that the capacity retention rate can reach 82.6% after 2000 cycles at 1 A g−1 (55.8% for pristine HC). This work provides a flexible and versatile surface modification method to improve the electrochemical property of HC, and hopefully accelerate the practical application of HC anodes for SIBs.

Sodium‐Ion Batteries In article number 2300002, Yu Li, Chuan Wu, Ying Bai, and co‐workers develop an efficient strategy to reconstruct the surface functionality of hard carbons in situ, which can controllably catalyze preferential salt decomposition to form an inorganic‐rich and layered solid electrolyte interphase (SEI). The structurally stable and ion‐conductive SEI enables advanced hard carbon anodes with an ultrahigh initial Coulombic efficiency and long cycling life for sodium‐ion batteries.