Tailoring crystalline phases of MoO2 for enhanced lithium-ion storage performance

Abstract

Molybdenum dioxide has emerged as a promising anode material for lithium-ion batteries (LIBs), owing to its distinct advantages of high theoretical specific capacity, efficient charge transfer kinetics, and multivalent oxidation states. Its layered crystal structure facilitates rapid Li⁺ diffusion, while its multielectron transfer mechanism enables enhanced energy storage density, positioning it as a competitive alternative to conventional graphite anodes. We achieve the layered structure by synthesizing amorphous molybdenum dioxide (MoO_2−x) through a solution-based approach combined with low-temperature annealing. This tackles the critical challenges of structural degradation and restricted conductivity commonly encountered in transition metal oxide anodes. The non-crystalline structure of the as-prepared material induces reconfigured atomic arrangements, leading to a marked improvement in electronic conductivity and an enhancement in the kinetic response of Li⁺ insertion/extraction reactions during extended charge–discharge cycles. Electrochemical tests demonstrate that the optimized amorphous MoO_2−x anode demonstrates an exceptional reversible discharge capacity of 817.1 mAh g⁻¹ at a current density of 0.1 A g⁻¹. Moreover, the material exhibits exceptional cycling durability, retaining a capacity of 436.3 mAh g⁻¹ even after 500 charge–discharge cycles at an elevated current density of 5.0 A g⁻¹. Empirical evidence demonstrates that amorphous phase engineering significantly enhances both the structural integrity and cycling stability of MoO_2−x, facilitating its real-world implementation as a superior anode material in next-generation lithium-ion battery systems. This observation highlights the potential of non-crystalline design strategies as a systematic approach for optimizing transition metal oxide-based anodes for advanced energy storage technologies.