Carbon coating and oxygen vacancies modulated hierarchical urchin-like MoNb12O33 microspheres for superior lithium-ion storage

Abstract

MoNb₁₂O₃₃ has garnered interest as a potential anode for lithium-ion batteries because of its high theoretical capacity, safe operating voltage, and excellent structural stability. However, its slow Li-ion diffusion kinetic and comparatively low electrical conductivity hamper its practical application. Herein, oxygen vacancies and nitrogen-doped carbon coating co-modify three-dimensional hierarchical urchin-like MoNb₁₂O₃₃ were made using the hydrothermal and polydopamine carbonization process. As anode applied in LIBs, MoNb₁₂O₃₃@N-C composite exhibits superior rate capacity (192 mAh g^-1 at 30 C), and excellent cycling stability (90.3% capacity retention at 10 C after 500 cycles). Moreover, a full cell with MoNb₁₂O₃₃@N-C as the anode also demonstrated excellent electrochemical performance. The improved lithium storage performance of MoNb₁₂O₃₃@N-C can be attributed to the synergistic effects of its unique hierarchical urchin-like structure, N-doped carbon coating, and oxygen vacancies. These factors reduce the Li⁺/electron transfer distances, mitigate volume fluctuations of the active substance, improve the electrical conductivity and Li⁺ diffusion, and enhance the quantity of reactive sites and structural stability.