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Carbon-coated silica(SiO2)and molybdenum carbide(Mo2C)particles are prepared by sol-gel method using tetraethyl silicate，ammonium molybdate and sucrose as silicon，molybdenum and carbon sources，respectively. The phase composition，morphology and structure of the composite are characterized by means of X-ray diffractometer， transmission electron microscope and other instruments， and the electrochemical performance of the composite as a negative electrode material for lithium ion batteries is also studied. The results show that when the mass ratio of tetraethyl silicate，ammonium molybdate and sucrose is 3∶1∶2(denoted as SiO2/Mo2C/C 2)，it has good electrochemical performance when it is used as the negative electrode material of lithium ion battery. At the current density of 100 mA/g，the first charge and discharge specific capacities are 662 mA·h/g and 896 mA·h/g，respectively，and the reversible capacity can still reach 625 mA·h/g after 200 cycles. Even at a larger current density of 2 A/g，the reversible capacity can still reach 272 mA·h/g. The composite exhibits good rate performance and cycling stability，which is mainly attributed to the good stability and high electrical conductivity of Mo2C which can effectively improve the poor conductivity of SiO2 itself. The core material directly reacts with the electrolyte to generate by-products，and in addition，it can be used as a buffer layer to slow down the volume expansion of SiO2，so the electrochemical performance of the material is significantly improved during the charging and discharging process. The new idea of using transition metal carbides to modify the poor conductivity and cycle performance of SiO2 proposed here can provide new research ideas and broaden the research direction for the modification of other anode materials. [ABSTRACT FROM AUTHOR]

:Transition metal light elements compounds (TMLEs) are a kind of robust functional materials due to high hardness, high melting point, superior conductivity, magnetic properties, and superconductivity. And high hardness allows TMLEs can be used in extreme evironment. While, synthesizing TMLEs need high pressure and high temperature (HPHT) conditions to overcome the energy barrier. Although many TMLEs were synthesized by HPHT, the growth mechanism is still mysterious. Summary of TMLEs synthesized by HPHT is significant to understand the growth process and developing of new TMLEs. In this work, the TMLEs synthesized by HPHT which include our groups research experience and other relevant literatures are summarized. The TMLEs include transition metal borides (TMBs), transition metal carbides (TMCs), and transition metal nitrides (TMNs). The starting materials, experimental conditions, and morphologies etc. are analyzed. It can be found that proportion of starting materials and the suitable temperature are very important to obtain the single phase of TMBs; the boron subunit in TMBs is related to growth kinetics, which induces step growth process; choosing different starting materials of carbon and nitrogen will define the growth process of TMLEs. Synthesizing single crystal with millimeter size in the future is meaningful to understand the basic properties of TMLEs. And study the new structure of TMLEs which has high of light elements is still urgent. With developing of new materials, TMLEs will be a kind of irreplaceable robust materials in the future [ABSTRACT FROM AUTHOR]