Ultrafast and stable ion/electron transport of MnNb2O6 in LIC/SC via interface protection and lattice defects.

Interface protection and kinetics optimization could effectively relieve the shortcomings of bimetallic oxides, such as low conductivity, strong hydrophobicity, insufficient ion diffusion rate and metal interatomic instability. In this work, ultrathin amorphous carbon shells and lattice defects (heteroatoms and vacancies) are introduced into the MnNb2O6 nanofiber surface to improve the electron/ion kinetic stability, conductivity and electrochemical activity. The ultrathin carbon interface protects unstable lattice with defects, thus restraining the adverse reaction between bimetallic oxides and electrolyte. Especially, ultrathin amorphous carbon layer enhances the stability and uniformity of ion transport as the substitute of solid-liquid ion exchange membrane. Lattice defects (N doping and oxygen vacancy) also enhance the ionic kinetics of the material. MnNb2O6 nanofiber, being optimized by interface protection and lattice defects, shows excellent electrochemical performances in Lithium-ion battery and supercapacitor.