Interlayer engineering in V6O13 nanobelts toward superior Mg-ion storage

Abstract

Magnesium-ion batteries are considered as a potential candidate to replace lithium-ion batteries owing to their advantages such as high theoretical capacity, high natural abundance and favorable safety. However, the exploitation of desirable cathode materials suffers from sluggish Mg²⁺ intercalation kinetics, resulting in poor specific capacity and terrible rate capability. Herein, an in situ polyaniline-intercalation strategy is developed to enlarge the interlayer distance of V₆O₁₃, thus boosting the Mg²⁺ intercalation kinetics. More critically, the strong coulombic interaction between divalent Mg²⁺ and anions in the host materials is another key factor hindering the Mg²⁺ diffusion kinetics, which can be effectively weakened by the π-conjugated structure of the polyaniline molecule. Reflected in magnesium-ion batteries, polyaniline-intercalated V₆O₁₃ exhibits high reversible capacity, superior rate capability and outstanding cycling stability. Such a novel strategy can also be utilized widely in other layered structure materials, which opens up a new avenue for exploiting desirable multivalent-ion battery cathode materials.