ZnO-Carbon Nanostructure Derived from Metal-Organic Framework As Stable Lithium Metal Anodes

Recently, research interest in next-generation rechargeable batteries is focused on lithium (Li) metal batteries due to its high specific capacity (3860 mA h g –1 ) and lowest redox potential (–3.04 V vs standard hydrogen electrode). However, they have two serious drawbacks, which are unstable Li deposition/dissolution during cycling and low cycle efficiency, to use in practical Li storage applications. These problems are strongly related to dendritic Li growth mechanism, and many strategies have been proposed to suppress the Li dendritic growth. One of the favorable method is to control the stability of surfaces by designing stable artificial interfaces for Li nucleation and growth. In this study, we adopted a simple sol-gel method to synthesize the zeolitic imidaloate framework-8 (ZIF-8). ZIF-derived nitrogen-doped ZnO-carbon scaffold was obtained by pyrolysis of ZIF to construct the novel structure for Li deposition. The porous electrode can reduce intensive local current density for Li metal growth. The three-dimensionally interconnected porous surface confines the metallic Li within the nanostructure leading to filling the ZnO-carbon scaffold as well as covering the electrode surface. We demonstrate a design of ZIF-derived lithiophilic ZnO-carbon nanostructure to use as a Li metal anode. The obtained porous electrode provides fast electron transfer and Li ion diffusion as well as reduces the local current density. As a result, the structure leads to flat voltage profiles and stable cycle life over 100 cycles at a current density of 2 mA cm –2 .