Progress in preparation and application for alkali metal ion battery anodes of dealloyed nanomaterials

SONY achieved the commercialization of lithium-ion batteries (LIBs) in 1991. Compared with traditional lead-acid and nickel-cadmium secondary batteries, the novel energy storage device offers the advantages of no memory effect, longer cycle life, and higher energy density. The continuous development of electrolytes, electrode structure, and battery production has resulted in the doubling of the energy density of LIBs since 1991. Lithium resources are limited, expensive, and unevenly distributed. Researchers are committed to replacing lithium with other inexpensive alkali metals, such as sodium and potassium, to reduce cost and save lithium resources. Sodium ion batteries (SIBs) and potassium ion batteries (PIBs) have attracted increasing attention because of their relatively low cost and abundant reserves. With the rapid development of electric automobiles, battery anode materials with high energy density have been drawing increasing attention. Owing to their high energy capacity, Group IV elements (Si, Ge, and Sn) and Group V elements (Sb and Bi) are considered appealing anode materials for LIBs, SIBs, and PIBs. Various methods, such as the hydrothermal method, template method, chemical precipitation, and magnetron sputtering method, are used for preparing anode materials. The dealloying technique is considered an effective method to fabricate alkali metal ion battery anode materials because of its scalable production, controllable structure, and low cost. This is a typical process in which the active components in the precursor alloy are selectively removed, with the residual components reorganizing into a nanostructure with specific morphology and space arrangement. The size, dimension, and morphology of battery anode materials play a considerable role in boosting electrochemical performance. The dealloying technique can be used to achieve the dynamic control of structure, morphology, and spatial arrangement by regulating dealloying and subsequent treatment processes. It can be categorized as chemical, electrochemical, liquid metal, and vapor phase dealloying. Thus far, researchers have successfully synthesized several nanomaterials via the dealloying technique, including three-dimensional (3D) nanoporous Si, 3D nanoporous Ge, 2D Si nanosheets, 1D Bi nanorods, and 0D Sb nanoparticles. Compared with bulk materials, dealloyed nanomaterials have large specific surface areas and remarkable structural stability. Hence, when used as anodes for LIBs, SIBs, and PIBs, dealloyed nanomaterial anodes usually deliver outstanding electrochemical performance. This review describes the common classification of dealloying techniques and the representative research progress. Emphasis is placed on the preparation of dealloyed nanomaterials with various dimensions and the application of dealloyed nanomaterials in alkali metal ion batteries. Finally, the development trend of dealloying and its application prospects in energy storage are also discussed.