Dual-directional electronic modulation of manganese oxides enabled by heterostructures for efficient sodium ion storage

Abstract

Heterostructures of manganese oxides (MnOx, i.e., MnO and Mn3O4) with carbon nitride (CN@MnOx) are prepared to boost the Na + storage capability of MnOx. Two different interfacial electric fields originated from the electronic redistribution at the interfaces of CN@MnO and CN@Mn3O4 endow CN@MnOx with high reversible capacity of 305 F g−1 at 1 A g−1, ultrahigh rate capability of 223 F g−1 at 20 A g−1, and exceptional long-term cycling lifespan without significant capacity decay up to 5000 cycles at 1 A g−1. An asymmetric supercapacitor based on CN@MnOx electrode materials delivers a high energy density of 46.7 Wh kg−1 at a power density of 1000 W kg−1. Mechanism studies showed that the enhanced sodium ion storage performance in CN@MnOx is attributed to a dual-directional electronic modulation of MnOx, which simultaneously improve the electronic conductivity and accelerate the Na+ transfer kinetics. This work opens up a unique strategy to regulate the electronic structure of multi-phase electrode materials, and meanwhile provides new clues for the energy storage mechanism in multi-phase electrode materials.