Fabrication\nof Self-Assembled Graphene Oxide Film\nand Its Application in Aqueous Zinc Metal Batteries

Fabrication of well-dispersed thin\ngraphene oxide (GO) films (GOFs)\nhas always been a challenge. Herein, a quick preparation method for\nGOFs was developed using our homemade GO with a large lateral size.\nThe film can be prepared in less than 2 h via a metal framework-induced\nself-assembly process. The thickness of the films can be as thin as\n∼15.5 μm, which will be thinner with compression. When\nit is used as a flexible modification layer on the Zn metal for aqueous\nZn-ion batteries, Zn can grow along the [010] direction in plane and\nstack orderly along the [002] direction even on the Cu substrate with\nGOF through epitaxial plating owing to negligible lattice mismatch\nbetween the (002) plane of Zn and the hexagonal ring [also (002) plane\nfor graphite] of GO. Meanwhile, the rich O groups on the GO film can\nprovide abundant zincophilic points and promote uniform distribution\nof Zn<sup>2+</sup> around the anode. Finally, dendrite-free and dense\nZn stripping/plating can be achieved and well remained. The GOF@Zn\nsymmetric cell reveals long cyclic stability of 1300 h at 1 mA cm<sup>–2</sup> and 1 mA h cm<sup>–2</sup>. It still can remain\nat 350 h even at a very high current density of 10 mA cm<sup>–2</sup> accompanied by a high areal capacity of 10 mA h cm<sup>–2</sup>. With the same plating amount of 5 mA h cm<sup>–2</sup>,\nthe thickness of the plated Zn is only ∼10 μm with GOF\nmodification, very close to the theoretical value of 8.54 μm,\nmuch thinner than that without GOF (∼18 μm), indicating\nvery dense deposition. Full cells assembled with the GOF@Zn anode\nand the MnO<sub>2</sub> cathode exhibit a capacity retention rate\nof 71% over 1000 cycles at 0.7 A g<sup>–1</sup>, showing much\nbetter cycling performance than that using bare Zn.