Elevating the Orbital Energy Level of dxy in MnO6 via d–π Conjugation Enables Exceptional Sodium‐Storage Performance

Abstract

AbstractTransition metal oxides (TMOs) suffer from inherently low electronic conductivity, while atom orbital related regulation can be critical to promote the electron transfer kinetics in energy storage applications. Herein, the study utilizes a d–π conjugation strategy to improve the electronic conductivity of TMOs. Briefly, phthalocyanine (Pc) molecules with large conjugated systems are selected to modify transition metal oxide (δ‐MnO2). By density functional theory (DFT) simulations, it is clarified that the strong d–π conjugation between MnO2 and Pc can elevate the orbital energy level of low energy orbital (dxy) in MnO6 units, which further activates the redox activity of dxy. The delocalized π electrons from Pc to MnO6 unit repel the original dxy electrons, and then elevate the dxy orbital energy level, thus facilitating the electron transfer in MnO2‐Pc. Subsequently, the MnO2‐Pc exhibits a significant specific capacitance of 310 F g−1 at 1 A g−1. At a power density of 900 W kg−1, the fabricated asymmetric supercapacitor delivers a maximal energy density of 50.3 Wh kg−1. This work paves the way to boost the redox activity of transition metal center in TMOs by regulating the orbital energy level, which can be expanded to design other advanced energy materials.