Sodium-ion batteries (SIBs) are considered as promising alternatives to lithium-ion batteries owing to the abundant sodium resources. However, the limited energy density, moderate cycling life, and immature manufacture technology of SIBs are the major challenges hindering their practical application. Recently, numerous efforts are devoted to developing novel electrode materials with high specific capacities and long durability. In comparison with carbonaceous materials (e.g., hard carbon), partial Group IVA and VA elements, such as Sn, Sb, and P, possess high theoretical specific capacities for sodium storage based on the alloying reaction mechanism, demonstrating great potential for high-energy SIBs. In this review, the recent research progress of alloy-type anodes and their compounds for sodium storage is summarized. Specific efforts to enhance the electrochemical performance of the alloy-based anode materials are discussed, and the challenges and perspectives regarding these anode materials are proposed.

Sodium‐ion batteries (SIBs) have been considered as the most promising candidate for large‐scale energy storage system owing to the economic efficiency resulting from abundant sodium resources, superior safety, and similar chemical properties to the commercial lithium‐ion battery. Despite the long period of academic research, how to realize sodium‐ion battery commercialization for market applications is still a great challenge. Thus, from the perspective of future practical application, this review will identify the factors that are restricting commercialization, and evaluate the existing active materials and sodium‐ion‐based full‐cell system. The design and development trends that are needed for SIBs to meet the requirements of practical applications in large‐scale energy storage will also be discussed in detail.

Constructing a heterojunction and introducing an interfacial interaction by designing ideal structures have the inherent advantages of optimizing electronic structures and macroscopic mechanical properties. An exquisite hierarchical heterogeneous structure of bimetal sulfide Sb 2 S 3 @FeS 2 hollow nanorods embedded into a nitrogen-doped carbon matrix is fabricated by a concise two-step solvothermal method. The FeS 2 interlayer expands in situ grow on the interface of hollow Sb 2 S 3 nanorods within the nitrogen-doped graphene matrix, forming a delicate heterostructure. Such a well-designed architecture affords rapid Na + diffusion and improves charge transfer at the heterointerfaces. Meanwhile, the strongly synergistic coupling interaction among the interior Sb 2 S 3 , interlayer FeS 2 , and external nitrogen-doped carbon matrix creates a stable nanostructure, which extremely accelerates the electronic/ion transport and effectively alleviates the volume expansion upon long cyclic performance. As a result, the composite, as an anode material for sodium-ion batteries, exhibits a superior rate capability of 537.9 mAh g −1 at 10 A g −1 and excellent cyclic stability with 85.7% capacity retention after 1000 cycles at 5 A g −1 .Based on the DFT calculation, the existing constructing heterojunction in this composite can not only optimize the electronic structure to enhance the conductivity but also favor the Na 2 S adsorption energy to accelerate the reaction kinetics. The outstanding electrochemical performance sheds light on the strategy by the rational design of hierarchical heterogeneous nanostructures for energy storage applications.

Phosphorus doping is an effective strategy to simultaneously improve the electronic conductivity and regulate the ionic diffusion kinetics of TiO2 being considered as anode materials for sodium ion batteries. However, efficient phosphorus doping at high concentration in well-crystallized TiO2 nanoparticles is still a big challenge. Herein, we propose a defect-assisted phosphorus doping strategy to selectively engineer the surface structure of TiO2 nanoparticles. The reduced TiO2–x shell layer that is rich in oxygen defects and Ti3+ species precisely triggered a high concentration of phosphorus doping (∼7.8 at. %), and consequently a TiO2@TiO2–x -P core@shell architecture was produced. Comprehensive characterizations and first-principle calculations proved that the surface-functionalized TiO2–x -P thin layer endowed the TiO2@TiO2–x -P with substantially enhanced electronic conductivity and accelerated Na ion transportation, resulting in great rate capability (167 mA h g–1 at 10 000 mA g–1) and stable cycling (99% after 5000 cycles at 10 A g–1). Combining in/ex situ X-ray diffraction with ex situ electron spin resonance clearly demonstrated the high reversibility and robust mechanical behavior of TiO2@TiO2–x -P upon long-term cycling. This work provides an interesting and effective strategy for precise heteroatoms doping to improve the electrochemical performance of nanoparticles.

Currently, the state-of-the-art lithium-ion batteries (LIBs) are the most widely used energy storage devices and have brought a great impact on our daily life. However, even many strategies have been reported to improve the energy density, these LIBs still can not meet the rapidly growing demand from the many lately emerged devices. During the pursue of higher energy densities, lithium-metal batteries (LMBs) have been the most promising candidates of the next-generation energy storage devices. Unfortunately, the Li-metal anode usually induces severe safety concerns and inferior cycle performance, because of the dendrite growth, high reactivity, and infinite volume changes of Li metal. As a result, these problems limit the commercial application of LMBs and must be resolved prior to the practical deployment of LMBs. In this review, we will firstly discuss the failure mechanisms of Li-metal anodes and introduce latest characterization technologies to study dendritic Li formation. The advances to improve the safety and performance of Li metal anode through electrolyte modification, interfacial engineering, solid-state electrolyte incorporation, and host materials design will then be comprehensively summarized and discussed. Lastly, we will conclude by summarizing the challenges in the current research on LMBs and highlight the future perspectives as well. Through this review, we hope to present the latest developments of the Li metal anode materials for the readers, and also shed light on the possible solutions for the current issues in order to accelerate both fundamental research and practical deployment of the various LMBs.