Heterostructure engineering of MnO/TiO2 embedded in N-doped hollow carbon nanofibers for superior sodium storage

TiO2-based materials are viewed as promising anodes for sodium-ion batteries due to their high theoretical capacity and superior structural stability, but they suffer from low electron conductivity and sluggish Na+ diffusion kinetics, which leads to inferior rate performance and cyclability. Herein, a novel MnO/TiO2 embedded into N-doped hollow carbon nanofibers (MnO/TiO2@N-C) is proposed to address this challenge via combining the heterostructure engineering and nanostructure designing. The integrated design greatly enhances the Na+ transfer and adsorption, provides more active interfacial sites and promotes the electric conductivity. The first -principle density functional theory calculations manifest that the constructed hetero-interfaces between MnO and TiO2 induce strong electric fields and accelerate Na+ transfer. Due to these merits, the MnO/TiO2@N-C exhibits a high reversible discharge capacity of 406.5 mA h g-1 at 0.3 A/g, superior rate capability (213.3 mA h g-1 at 3 A/g), and exceptional cycling performance (99.3 % capacity retention after 10,000 cycles at 3 A/g). In addition, the Na full cell based on MnO/TiO2@N-C anode exhibits a promising energy density of 332.8 Wh kg- 1 at 677.1 W Kg-1. This work offers a novel and an interesting strategy to improve electrochemical sodium storage of TiO2-based materials, which is significant for the practical applications of sodium-ion batteries.

Automated summary

A novel MnO/TiO2@N-C nanocomposite is proposed to improve the electrochemical sodium storage of TiO2-based materials by combining heterostructure engineering and nanostructure designing, which enhances Na+ transfer and adsorption, provides more active interfacial sites, and promotes electric conductivity. The nanocomposite exhibits high reversible discharge capacity, superior rate capability, exceptional cycling performance, and promising energy density, making it significant for the practical applications of sodium-ion batteries.