Monocrystal Cu₃Mo₂O₉ Confined in Polyaniline Protective Layer: an Effective Strategy for Promoting Lithium Storage Stability

Attributed to the high theoretical capacity and abundant reserve, Cu 3 Mo 2 O 9 has been considered as a potential anode material for lithium‐ion batteries. Nevertheless, the severe capacity fading caused by structure collapse and particle aggregation seriously hinders its practical application. In this work, Cu 3 Mo 2 O 9 coated with homogeneous polyaniline layer is obtained through oxidative polymerization of aniline on the surface of Cu 3 Mo 2 O 9 . The lithium storage performance is investigated systematically. As a result, a high reversible specific capacity of 800.2 mA h g −1 at a current density of 100 mA g −1 is delivered in Cu 3 Mo 2 O 9 @PANI anode even after 200 cycles, which is much higher than that of pristine Cu 3 Mo 2 O 9 anode (373.8 mA h g −1 ). Furthermore, a high capacity of 675 mA h g −1 at a high current density of 1 A g −1 is achieved even after 700 cycles. This result evidences that the introduction of a polyaniline protective layer is an effective way to improve the structural stability of the Cu 3 Mo 2 O 9 anode and further enhance cycling durability. This strategy is a starting point for the preparation and stabilization of other binary metal oxide composite materials for applications in lithium‐ion batteries.