The energy storage application of core-/yolk–shell structures in sodium batteries

Abstract

Materials with a core–shell and yolk–shell structure have attracted considerable attention owing to their attractive properties for application in Na batteries and other electrochemical energy storage systems. Specifically, their large surface area, optimum void space, porosity, cavities, and diffusion length facilitate faster ion diffusion, thus promoting energy storage applications. This review presents the systematic design of core–shell and yolk–shell materials and their Na storage capacity. The design of different metal structures with different shapes and their corresponding synthesis methods are also highlighted. Moreover, changes in capacity with a variation in the carbon moiety and porosity in terms of applications are highlighted. Furthermore, to compete with the dominant Li batteries in the market, materials with low-cost large-scale production and high active mass loading need to be developed. Thus, both yolk- and core–shell structures have been designed considering their significant structural advantages for application in Na batteries and their impacts on the rate capacity and reversible capacity. This review also demonstrates the advantages of yolk–shell and core–shell structures in faster Na ion transportation and excellent cycling stability. Furthermore, the synergistic effect of the core–shell structure enhances reversible capacity. Additionally, the conducting coating of the encapsulated structure increases electron transport, and a higher exposure of the electrode to the electrolyte is further beneficial for the growth of a stable SEI layer. Considering these advantages and disadvantages, this review may help guide the future advancement of sodium batteries (SIBs) in upcoming research based on the advantages of the core–shell and yolk–shell morphology. Finally, future perspectives regarding machine learning (ML) to access better performances in Na batteries are discussed.