Two-Dimensional Nanosheet Stacking Structure Films for Li/Na/K-Ion Batteries and Supercapacitors

Secondary batteries and supercapacitors are currently the most promising energy storage devices. The energy storage performance of these devices is mainly dependent on the structure and electrode materials. Compared to zero-dimensional (0D) and one-dimensional (1D) nanomaterials, two-dimensional (2D) materials have advantages such as short ion diffusion and electron transfer paths, large specific surface area, and good flexibility. The nanosheet stacking structure film formed by the assembly of nanosheets along the vertical direction of the substrate has obvious structural advantages for battery or supercapacitor electrodes, such as open ion diffusion and electron transport channels, inhibition of volume changes of electrochemically active species during ion insertion and extraction cycles, and improvement of electrode conductivity. In this Review, several common synthesis processes of 2D nanosheets by exfoliation and fabrication methods of nanosheet stacking structure films were first introduced. Then, the applications of nanosheet stacking structure films in secondary batteries and supercapacitors were introduced in detail. It should be pointed out that the nanosheet stacking structures mentioned in this article exist in the form of thin films, either deposited on substrates or as self-standing thin films. Finally, the limitations of nanosheet stacking structure films in the field of energy storage were summarized, and prospects for future development trends of the nanosheet stacking structure films in energy-related areas were highlighted.