Vertically Co-oriented Mn-Metal–Organic Framework Grown on 2D Cation-Intercalated Manganese Oxide via a Self-sacrificing Template Process for a High-Performance Asymmetric Supercapacitor

This is the authors' abstract. We don't add key points for this paper.

Metal–organic frameworks (MOFs) are a preferred electrode material choice due to their open crystalline framework and potential redox sites. However, their random crystal orientations and low conductivity hinder the straightforward applications. Herein, an accessibly manipulated strategy to prepare vertically co-oriented K0.5Mn2O4@Mn-MOF-8 nanosheet arrays by using K0.5Mn2O4 as both the template and the precursor is designed. The vertically co-oriented K0.5Mn2O4@Mn-MOF-8 achieves a high specific capacitance by increasing the Mn3+/Mn4+ redox couple and raising the conductivity due to the intercalation of the alkali cations (K+) of K0.5Mn2O4. Meanwhile, this structure conduces to shorten the charge-transfer path in electrochemical reactions. The K0.5Mn2O4@Mn-MOF-8 electrode exhibits excellent electrochemical performance (specific capacitance of 886.9 F g–1 at 1 A g–1). The asymmetric device (ASC) assembles with K0.5Mn2O4@Mn-MOF-8 and WO3 with a remarkable cycling ability (92.6% capacitance retention over 8000 cycles at 3 A g–1), and the potential window reaches 2 V. The ASC presents a high energy density of 42.94 Wh kg–1 with a power density of 1080.08 W kg–1. This convenient method provides a complete strategy for the uniform assembly of vertically co-oriented MOF arrays on highly conductive substrates and serves in energy storage devices.