Tuning MnO₂: A Nernstian-Type Electrode Material as a Substitute for Bare Zinc Foil for Triggering the Performance of ZHS

In electrochemical energy storage, two factors─energy density and power density─have received significant attention. The fabrication of hybrid supercapacitors (HSCs), composed of battery- and capacitor-like electrodes, is an efficient way to obtain high energy and power densities in a single device. Currently, multivalent Zn2+ metal-ion HSC (ZHS) has attracted increasing attention due to its remarkable benefits. However, various challenges remain in the search for viable electrode materials with excellent electrochemical activity. Accordingly, W- and K-dual ion-intercalated layered MnO2 is introduced as a battery-type cathode material for fabricating high-performance ZHS. Optimized, 2W-KMO ZHS has delivered a specific capacity of ∼67 mAh·g–1 at a current density of 0.5 A·g–1. In addition, the device exhibits a power density of ∼499 W·kg–1 at an energy density of ∼67.1 Wh·kg–1 with a remarkable lifespan (∼91% capacity retention after 10,000 charge–discharge cycles at a current density of 10 A·g–1). This study opens up the possibilities of viable electrode design of high-performing ZHSs and takes a step forward to the practical application of HSC.