Low-temperature synthesis of CeB6 nanowires and nanoparticles as feasible lithium-ion anode materials

Abstract

Metallic CeB6 nanomaterials were prepared via the low-temperature solution combustion method (nanoparticles) and high-pressure solid state reaction (nanowires). X-ray diffraction patterns and High-resolution transmission electron microscopy images reveal that CeB6 nanoparticles are highly crystalline and CeB6 nanowires are single crystals. The X-ray photoelectron spectroscopy analysis indicates that the cerium is present in the +3 and +4 mixed-valence state in CeB6. As lithium-ion anodes, CeB6 nanowires (nanoparticles) electrode achieves a capacity of ~531 (338) mA h g−1 in the initial cycle and keeps a reversible capacity of ~225 (185) mA h g−1 after 60 cycles. CeB6 nanowires are tested for 6000 cycles at 1000 mA g−1, which shows a specific capacity approaching to the capacity at 100 mA g−1 in spite offluctuation within a narrow range, and keep ~168 mA h g−1 after 6000 cycles, indicating a stable cycling performance owing to the excellent metal-like conductivity of (~5.67 × 103 S m−1). The reason of capacity rising is that the reduction and oxidation levels of CeB6 electrodes are improved after the 2nd cycle with Li+ insertion/extraction. Meanwhile, kinetic analysis reveals that the Li+ storage mechanism is mainly controlled by a surface capacitive behavior.