Metal-organic frameworks derived anatase/rutile heterostructures with enhanced reaction kinetics for lithium and sodium storage

Heterostructured electrodes with interfacial effects have exhibited great potential in improving the electrochemical kinetic of electrode materials. Herein, to accelerate the sluggish kinetic of TiO2 electrodes in lithium ion batteries (LIBs) and sodium ion batteries (SIBs), anatase-rutile heterostructure with affluent surface/bulk oxygen vacancies was fabricated via an in-situ topological conversion strategy. The abundant surface/bulk oxygen vacancies, enhanced electronic conductivity and regulated C-N bonds accelerated the electronic/ionic transport and improved the pseudo-capacitive behaviors of the heterostructured electrode. Theoretical calculation corroborated that the introduction of anatase-rutile heterostructure favored the close connection between TiO2 and carbon layers, heightened the electronic conductivity of the composites and lowered the migration energy barriers of Li+ and Na+. Deservedly, TRA electrode with abundant anatase-rutile heterostructures delivered a ultrahigh rate capability of 334.9 mAh g(-1) in LIBs under an expanded potential range (3-0.05 V vs. Li/Li+) and a competitive reversible capability of 223.0 mAh g(-1) in SIBs at 3.36 A g(-1). This work not only revealed the migration/transformation process of Ti, O, C and N elements during the calcination of metal-organic framework, but also provided new insights into the charge storage mechanism of anatase-rutile heterostructure.

Automated summary

The fabricated anatase-rutile heterostructure TiO2 electrode with abundant oxygen vacancies exhibited enhanced electronic/ionic transport and improved pseudo-capacitive behaviors. The theoretical calculation confirmed that the heterostructure favored the connection between TiO2 and carbon layers, leading to improved electronic conductivity and lower migration energy barriers for Li+ and Na+.