caused by the large Na + radius (1.02 Å) lead to undesirable electrochemical performance, including low capacity, poor rate capability and short life span, which plagued the wide-scale application of SIBs. [3] Thus, exploring suitable anodes with rational design and controllable preparation aiming to improve the kinetic of sodiation and desodiation is believed to be an essential task to realize the practical usage of SIBs.By virtue of conspicuous features including high theoretical capacity and intrinsic metallic property, transition metal selenides are regarded as promising anodes for SIBs. Generally, the Na + -storage process of transition metal selenides refers to the reaction between Na and transition metal selenides involving the total reduction of the transition metal to its metallic or alloy states and subsequently endowing the high theoretical capacity. [4] Compared to materials based on insertion Na + -storage mechanism (such as carbon anodes), transition metal selenides exhibit higher specific capacity and better safety by avoiding the formation of sodium dendrite in the low voltage area. While compared to the corresponding metal oxides and sulfides, transition metal selenides display more favorable reactivity benefiting from the weaker metal-Se bond and better conductivity of discharged product (Na 2 Se). [5] Nevertheless, every coin has two sides. The sluggish kinetics coupled with the huge volume expansion caused by the crystal structure destruction and new phases formation during the electrochemical reaction process, lead to the unsatisfied capacity and limited cycling life. Therefore, plenty of efforts, such as designing a novel structure to exposure more active sites, [6,7] coupling with carbon matrix to improve the conductivity, [3,8] modifying the electrolyte to reduce the reaction energy barrier, and so on, [9] have been made to address the issues mentioned above. Nevertheless, these strategies are mainly focused on the external charge transfer tailing, severe electrode polarization and sluggish Na + diffusion kinetic are still crucial obstacles for the achieving high-performance SIBs.Defects and interface engineering have been proved to be igneous strategies to improve the physical and chemical properties of materials, which have attracted wide interests in energy storage areas. [10][11][12][13] As a typical point defect, vacancies can boost the electrochemical performance of metal-ionThe exploitation of effective strategies to accelerate the Na + diffusion kinetics and improve the structural stability in the electrode is extremely important for the development of high efficientcy sodium-ion batteries. Herein, Se vacancies and heterostructure engineering are utilized to improve the Na + -storage performance of transition metal selenides anode prepared through a facile two-in-one route. The experimental results coupled with theoretical calculations reveal that the successful construction of the Se vacancies and heterostructure interfaces can effectively lower the Na + diffusion barrier, accel...

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Lithium batteries (LBs) are developed tremendously owing to their excellent energy density as well as cyclic persistence, exhibiting promising applications from portable devices to e‐transportation and grid fields. However, with the ever‐increasing demand for intelligent wearable electronics, more requests are focused on high safety, good durability, and satisfied reliability of LBs. The self‐healing route, which can simulate the ability of organic organisms to repair damage and recover initial function through its intrinsic vitality, is believed to be an efficient strategy to alleviate the unavoidable physical or chemical fatigue and damage issues of LBs, beneficial for the realization of the above mentioned high requests. In this review, the applicability and development of self‐healing materials are summarized in electrodes, electrolytes, and interfacial layers in recent years, focusing on exploring the feasibility of different self‐healing strategies in LBs, discussing the advantages and disadvantages of existing strategies in different parts of batteries, and indicating the possible research directions for beginners who are interested in this field. Finally, the critical challenges and the future research directions as well as opportunities are prospected.

Lithium-ion batteries (LIBs) with high energy density and fastcharge capability are urgently required for the ever-growing demands for electric vehicles and hybrid electric vehicles. To achieve this demand, as one of the important components, electrolytes are required to work well at a high voltage to fulfill the good performance of high energy density batteries and facilitate the fast-charge process. In this review, we mainly focus on the electrolytes design for LIBs under high-voltage and fast-charge conditions. The bottlenecks and the typical resolving strategies referring to lithium salts, solvents, solid electrolyte interface, additives and solvent structures in electrolytes are presented in detail. Finally, we propose the challenges regarding electrolytes design insight and inspiration for LIBs under the two conditions to give a better guide for the rationale design of the high energy density and fast-charge devices in the future applications.