Achieving High-Temperature Stability of Metastable α-MoC1-x by Suppressing Phase Transformation with Mounted Atoms for Lithium Storage Performance

Despite a significant advancement in preparing metastable materials, one common problem is the strict and precious reaction conditions due to their metastable structures. Herein, we achieved the preparation of high-temperature stabilized metastable alpha-MoC1-x by mounting zinc atoms into its lattice structure. Such a structural construction could suppress the phase transformation from alpha-MoC1-x to beta-Mo2C through restricting the displacement of Mo atoms upon increased temperature. The resultant metastable alpha-MoC1-x can be stabilized up to 1000 degrees C and this stability temperature is the highest for the metastable alpha-MoC1-x so far. Synchrotron X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) confirm the structure of Zn-mounted alpha-MoC1-x. Density functional theory (DFT) calculations reveal that the introduction of the Zn atoms in the lattice structure of alpha-MoC1-x could significantly decrease the energy difference (Delta E) between alpha-MoC1-x and beta-Mo2C, thus effectively suppressing the phase transformation from alpha-MoC1-x to beta-Mo2C and accordingly maintaining the high-temperature stability of alpha-MoC1-x. This novel strategy can be used as a universal method to be extended to synthesize metastable alpha-MoC1-x from different precursors or other mounted elements. Moreover, the optimal product exhibits excellent lithium storage performances in terms of the cycling stability and rate performance.