Tuning\nMnO<sub>2</sub>: A Nernstian-Type Electrode\nMaterial as a Substitute for Bare Zinc Foil for Triggering the Performance\nof ZHS

In\nelectrochemical energy storage, two factorsenergy density\nand power densityhave received significant attention. The\nfabrication of hybrid supercapacitors (HSCs), composed of battery-\nand capacitor-like electrodes, is an efficient way to obtain high\nenergy and power densities in a single device. Currently, multivalent\nZn<sup>2+</sup> metal-ion HSC (ZHS) has attracted increasing attention\ndue to its remarkable benefits. However, various challenges remain\nin the search for viable electrode materials with excellent electrochemical\nactivity. Accordingly, W- and K-dual ion-intercalated layered MnO<sub>2</sub> is introduced as a battery-type cathode material for fabricating\nhigh-performance ZHS. Optimized, 2W-KMO ZHS has delivered a specific\ncapacity of ∼67 mAh·g<sup>–1</sup> at a current\ndensity of 0.5 A·g<sup>–1</sup>. In addition, the device\n exhibits a power density of ∼499 W·kg<sup>–1</sup> at an energy density of ∼67.1 Wh·kg<sup>–1</sup> with a remarkable lifespan (∼91% capacity retention after\n10,000 charge–discharge cycles at a current density of 10 A·g<sup>–1</sup>). This study opens up the possibilities of viable\nelectrode design of high-performing ZHSs and takes a step forward\nto the practical application of HSC.