Graphene as regulating zinc deposition layer for long-life zinc ion hybrid supercapacitors

Abstract Zinc ion hybrid supercapacitors (ZIHS) are promising aqueous energy storage devices due to their low-cost and excellent long cyclic stability. However, the poor stability caused by growth of zinc (Zn) dendrite due to Zn uneven deposition/stripping, which limits the applications of ZIHS. Hence, graphene is constructed as surface layer of Zn foil to inhibit the formation of protuberances and improve the cycle life of ZIHS. Moreover, the cyclic life of graphene@Zn anode in ZIHS at 1 A g−1 reaches at least 10,000 cycles, 200-fold higher than that of Zn foil anode. The ultra-long life of graphene@Zn electrode is attributed to abundant active sites on graphene for Zn2+ nucleation and subsequently uniform deposition. Importantly, graphene layers not only inhibit dendrites by guiding uniform Zn deposition, but also reduce the side-reactions by blocking the electrolyte. Overall, the proposed method to improve reversibility and cyclic stability of Zn anode looks promising for the development of large-scale ZIHS.