PPy-Coated Mo₃S₄/CoMo₂S₄ Nanotube-like Heterostructure for High-Performance Lithium Storage

Heterostructured materials show great potential to enhance the specific capacity, rate performance and cycling lifespan of lithium-ion batteries owing to their unique interfaces, robust architectures, and synergistic effects. Herein, a polypyrrole (PPy)-coated nanotube-like Mo₃S₄/CoMo₂S₄ heterostructure is prepared by the hydrothermal and subsequent in situ polymerization methods. The well-designed nanotube-like structure is beneficial to relieve the serious volume changes and facilitate the infiltration of electrolytes during the charge/discharge process. The Mo₃S₄/CoMo₂S₄ heterostructure could effectively enhance the electrical conductivity and Li⁺ transport kinetics owing to the refined energy band structure and the internal electric field at the heterostructure interface. Moreover, the conductive PPy-coated layer could inhibit the obvious volume expansion like a firm armor and further avoid the pulverization of the active material and aggregation of generated products. Benefiting from the synergistic effects of the well-designed heterostructure and PPy-coated nanotube-like architecture, the prepared Mo₃S₄/CoMo₂S₄ heterostructure delivers high reversible capacity (1251.3 mAh g^-1 at 300 mA g^-1), superior rate performance (340.3 mAh g^-1 at 5.0 A g^-1) and excellent cycling lifespan (744.1 mAh g^-1 after 600 cycles at a current density of 2.0 A g^-1). Such a design concept provides a promising strategy towards heterostructure materials to enhance their lithium storage performances and boost their practical applications.