Graphdiyne/Graphene/Graphdiyne Sandwiched Carbonaceous Anode for Potassium-Ion Batteries.

Graphdiyne (GDY) has been considered as an appealing anode candidate for K-ion storage since its triangular pore channel, alkyne-rich structure, and large interlayer spacing would endow it with abundant active sites and ideal diffusion paths for K-ions. Nevertheless, the low surface area and disordered structure of bulk GDY typically lead to unsatisfied K storage performance. Herein, we have designed a GDY/graphene/GDY (GDY/Gr/GDY) sandwiched architecture affording a high surface area and fine quality throughout a van der Waals epitaxy strategy. As tested in a half-cell configuration, the GDY/Gr/GDY electrode exhibits better capacity output, rate capability, and cyclic stability as compared to the bare GDY counterpart. In situ electrochemical impedance spectroscopy/Raman spectroscopy/transmission electron microscopy are further applied to probe the K-ion storage feature and disclose the favorable reversibility of GDY/Gr/GDY electrode during repeated potassiation/depotassiation. A full-cell device comprising a GDY/Gr/GDY anode and a potassium Prussian blue cathode enables a high cycling stability, demonstrative of the promising potential of the GDY/Gr/GDY anode for K-ion batteries.