Amorphous SnSe quantum dots anchoring on graphene as high performance anodes for battery/capacitor sodium ion storage

Amorphous structure materials have isotropic characteristics, which provides open active diffusion channels to facilitate the sodium ion diffusion and transport. In this work, amorphous SnSe quantum dots (~2 nm) anchoring on the nitrogen doped graphene (a-SnSe/rGO) are rational designed by facile one-pot solvothermal synthesis . The amorphous SnSe structure largely suppresses the volume change comes from the tin alloying reaction process, further decreases the particle pulverization. Strong Sn–C, Sn–O–C, and Se–C chemical bonds form between a-SnSe and graphene, guaranteeing rapid electrical transport channels during the sodiation/de-sodiation process. As a result, it presents superior electrochemical reversibility of 397 mA h g −1 at 1 A g −1 after 1400 cycles with 0.014% capacity fading per cycle as sodium ion battery anode. The excellent rate performance and the high proportion of pseudocapacitance contribution for a-SnSe/rGO also make it very suitable for the anode materials for sodium ion capacitor. It exhibits high energy density of 58 Wh k g −1 after 5000 cycles at 1 Ag -1 in optimized a-SnSe/rGO||AC sodium ion capacitor. The strategy of fabrication of amorphous nanostructure material provides brand new thoughts for development and application of metal chalcogenide in energy storage devices.