MoNb12O33 as a new anode material for high-capacity, safe, rapid and durable Li+ storage: structural characteristics, electrochemical properties and working mechanisms

Abstract

Intercalation-type niobium-based oxides are considered as promising anode materials for lithium-ion batteries owing to their high theoretical/practical capacities, long-term cyclability, and high safety. However, studies in this research field are still very limited. Here, we explore MoNb₁₂O₃₃ as the first molybdenum niobium oxide anode material, and prepare microsized MoNb₁₂O₃₃ particles (M-MoNb₁₂O₃₃) and porous MoNb₁₂O₃₃ microspheres (P-MoNb₁₂O₃₃) based on solid-state reaction and solvothermal methods, respectively. MoNb₁₂O₃₃ shows a Wadsley–Roth crystal structure, consisting of 3 × 4 × ∞ NbO₆ octahedra linked by corner-sharing MoO₄ tetrahedra. This very open and stable structure results in fast Li⁺ diffusivity and superior structural stability, respectively. These structural merits together with the nanosizing effects in P-MoNb₁₂O₃₃ lead to outstanding electrochemical properties in its half cell, including a high practical capacity (321 mA h g⁻¹ at 0.1C), significant intercalation pseudocapacitive contribution (85.5% at 1.1 mV s⁻¹), prominent rate capability (200 mA h g⁻¹ at 10C), and superior cyclability (capacity retention of 95.7% after 1000 cycles at 10C). Moreover, outstanding electrochemical properties of a LiMn₂O₄//P-MoNb₁₂O₃₃ full cell are also achieved, such as a high reversible capacity (274 mA h g⁻¹ at 0.1C), good rate capability (106 mA h g⁻¹ at 10C), and superior cyclability (capacity retention of 93.9% after 1000 cycles at 5C). All these findings indicate that P-MoNb₁₂O₃₃ can be a practical anode material for high-capacity, safe, rapid and durable Li⁺ storage.