Smart construction of 3D N-doped graphene honeycombs with (NH4)2SO4 as a multifunctional template for Li-ion battery anode: “A choice that serves three purposes”

Abstract

Not only do theoretical studies predict that doping graphene with nitrogen can tailor its electronic properties and chemical reactivity but practical results have also shown that tuning the shapes of graphene could make it more applicable in electronic devices. However, the successful transfer of lab procedures to commercialization and scale-up fabrication of N-doped graphene with specific architectures still faces great challenges at the moment. Herein, we report a smart approach to rationally design and deliberately construct 3D N-doped honeycomb-structured graphene, denoted as 3D-NHrGO, by a (NH₄)₂SO₄-templated self-assembly method in which (NH₄)₂SO₄ plays the role of “a choice that serves three purposes”. (NH₄)₂SO₄ can not only facilitate the ultrafast separation of GO from the obtained mixed liquor of Hummers’ method, but also act as a nitrogen source and a green template to tailor the electronic properties as well as control the morphology of 3D-NHrGO, respectively. Particularly, (NH₄)₂SO₄ can be recovered with simple recrystallization at the end of the synthesis, which makes the process environment-friendly and resource-effective. The compositions, structures, and morphologies of the samples during overall evolution of the synthetic procedure were investigated, and the substitution of N in the graphene framework is also evidenced. When evaluated as an anode material for Li-ion battery, the 3D-NHrGO gives high rate capability and stable cycle life. This research inspires new methodologies in addressing the enormous problems associated with the traditional graphene preparation process while using GO as the precursor, and sheds light on the great potential of industrially viable manufacturing of 3D N-doped graphene architectures for other applications.