Pre-intercalation of potassium to improve the electrochemical performance of carbon-coated MoO3 cathode materials for lithium batteries

Abstract

Low conductivity and irreversible structure change impede the practical use of MoO3 as cathode material for rechargeable lithium batteries. In this article, to address these issues, carbon-coated and K-doped MoO3 composite materials (KxMoO3@C) were prepared by hydrothermal treatment followed by a high-temperature annealing. Benefiting from the doped K+ ions, the interlayer spacing of crystal is expanded, and the layered structure of MoO3 is stabilized at the same time. Besides, electric conductivity of the KxMoO3 is enhanced by surface coating of carbon layer. Consequently, electrochemical properties of the KxMoO3@C composites are improved remarkably. The as-prepared K0·046MoO3@C composites can deliver the specific capacities of 258 and 118 mAh g−1 at the current densities of 30 and 3000 mA g−1 over the potential range of 1.5–4.0 V (vs. Li+/Li) respectively, displaying an outstanding rate capability. When cycled at 1500 mA g−1, it can retain 83.9% of the initial capacity after 500 cycles, exhibiting a long-term span life. Our results suggest that synergistic effects of the carbon coating and the interlayered doping of K+ ions can significantly improve the electrochemical performance of the MoO3 cathode, making it promising to be used in rechargeable lithium batteries.