Group IV elemental 2D materials beyond graphene used as electrodes for alkali-ion batteries

The group IV elemental materials, especially Si and Ge, have been conventionally used as the anodes for lithium-ion batteries. As the research field of two-dimensional (2D) materials was pioneered, the distinct phases of Si, Ge, and even Sn have begun to be investigated for energy storage devices. Moreover, their potential applications are extended from lithium-ion to sodium-ion and potassium-ion batteries. This article briefly introduces the mainstream production methods of the group IV elemental 2D materials beyond graphene and then discusses in detail the studies concerning their electrode applications in alkali-ion batteries. Eventually, the superiority and inferiority of the preparation approaches, the crystal structures of the materials obtained by various methods, the charge-discharge mechanisms causing the improved battery performance, and the urgent challenges as well as possible solutions for future development of alkali-ion batteries with the electrodes of silicene, germanene, or stanene, would be summarized.