Fluorine-Enriched Graphdiyne as an Efficient Anode in Lithium-Ion Capacitors

Lithium-ion capacitors (LICs) have shown extraordinary promise for electrochemical energy storage but are usually limited to electrodes with low energy density or power density owing to the lack of active storage sites and ion diffusion limitation. In this study, fluorine-enriched graphdiyne (F-GDY) is prepared by a solvothermal reaction. Owing to the 42-C hexagonal porous structure, abundant sp and sp² hybrid carbon atoms, and even distribution of fluorine, F-GDY has enormous potential as an anode for lithium-ion storage. The outstanding rate performance (1825.9 mAh g^-1 at 0.1 A g^-1 , 979.2 mAh g^-1 at 5 A g^-1 ) and stable cycling stability of F-GDY in the lithium-ion battery inspire the assembly of a LIC with F-GDY as an anode and activated carbon (AC) as a cathode. When the AC/F-GDY mass ratio is 7:1, the LIC gives the largest energy density of 200.2 Wh kg^-1 , corresponding to a power density of 131.17 W kg^-1 . This LIC also shows excellent long-term cycling stability with a retention of approximately 80 % after 5000 cycles at 2 A g^-1 and a retention of more than 80 % after 6000 cycles at 5 A g^-1 .