PPy@h-MoO3 nanorods as the cathode material for high-efficiency lithium-ion batteries

Abstract

Achieving high-energy density and ensuring cycling stability in rechargeable lithium-ion batteries (LIBs) pose significant challenges in the context of both environmentally friendly and commercial applications. Layered transition metal oxides (LTMOs) are attracting increasing attention as cathode materials for state-of-the-art performance LIBs. However, the application of such positive electrode materials is still limited by their sluggish redox kinetics and huge volume changes. Herein, we demonstrate a high quality, unique crystalline, smart surface coating of polypyrrole (PPy) over hexagonal molybdenum trioxide nanorods (h-MoO₃ NRs), with a length of 3–5 μm and diameter of 175–200 nm. Crystalline h-MoO₃ nanorods (NRs) with a coating of polypyrrole were synthesized by multiple steps, sonication, heating, autoclaving, and polymerization. During the cycling process, the coating of PPy not only avoids or hinders the dissipation of Mo ions and mitigates large changes in volume but also exhibits admirable conductive binder function between the particles to increase the contact. As a result, the PPy@h-MoO₃ NR electrodes manifest an initial discharge-specific capacity of 954 mA h g⁻¹, with a Coulombic efficiency of 98%. Notably, even after 100 cycles, PPy@h-MoO₃ NRs demonstrate a specific capacity of 905 mA h g⁻¹ with a remarkable capacity retention of 95% for LIBs, showcasing ultra-high capacity and excellent cycling stability.