Metal–Organic\nFramework/Polyaniline Nanocomposites\nfor Lightweight Energy Storage

Abstract

We describe a simple strategy to\nmodify zeolitic imidazolate framework-8\n(ZIF-8) using polyaniline (PANI) via a controlled interfacial polymerization\nmethod, without using a template, to synthesize ZIF-8/PANI nanocomposites.\nOur method avoids the agglomeration of ZIF-8/PANI, boosts the utilization\nof active materials, and exposes more active sites, and hence, it\nis advantageous to facile electron transfer. Because of its unique\nhierarchical structure, ZIF-8/PANI has a high surface area (610.8\nm²·g^–1) and the ZIF-8/PANI electrode\nexhibited a capacitance value of 395.4 F·g^–1 at 0.2 A·g^–1, which is the highest among\nthe metal–organic framework (MOF)-based composites reported\nto date. A solid-state asymmetric supercapacitor (SASC) fabricated\nwith ZIF-8/PANI as the electrode showed good capacitive behavior over\na wide potential window from 0 to 2.5 V without nonaqueous electrolytes.\nIt exhibited a specific areal capacitance of 28.1 mF·cm^–2 at 0.1 mA·cm^–2, which is much higher than\nthe values reported for other MOF-based supercapacitors. The SASC\nalso possessed a high energy density (3.2 μW h·cm^–2) and power density (1.1 mW·cm^–2), good cycling\nstability, and flexibility. These characteristics make our ZIF-8/PANI\nnanocomposite an excellent MOF-based electrode for highly flexible\nand lightweight energy storage applications.