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

Heterostructures of manganese oxides (MnO x , i.e., MnO and Mn 3 O 4 ) with carbon nitride (CN@MnO x ) are prepared to boost the Na + storage capability of MnO x . Two different interfacial electric fields originated from the electronic redistribution at the interfaces of CN@MnO and CN@Mn 3 O 4 endow CN@MnO x 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@MnO x 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@MnO x is attributed to a dual-directional electronic modulation of MnO x , 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. • The electronic structure of multi-phase CN@MnO x is successfully regulated. • Dual electric fields are induced by dual-directional redistribution of charges. • The resultant CN@MnO x displays high capacity and significant rate capability.