磷化钴微米花的制备及电化学性能

Synthesis and Electrochemical Properties of Cobalt Phosphide Micron-sized Flowers

通过简单的溶剂热,以水(H_2O)和无水乙醇(EtOH)作为混合溶剂,采用十六烷基三甲基溴化铵(CTAB)为表面活性剂成功地制备出均匀整齐的磷化钴(Co_2P)微米花。结果表明,所得产物为纯的斜方Co_2P,结晶度良好,其形貌为由大量长约1~1.5μm锥棒组成的花状。表面活性剂用量,水与无水乙醇体积比,反应时间对产物的形成均有一定的影响。其中,适量的CTAB能在水-乙醇体系中电离产生自由的十六烷基三甲铵阳离子(CTA^+),吸附在Co_2P晶体的某些晶面,对定向生长成花状形貌起重要作用。此外,以所制备Co_2P微米花作为锂电池负极材料,对其电化学性能进行研究。结果表明,样品的初始放电容量达到468.4mA·h/g,循环100次后,仍稳定在170mA·h/g左右。

The micron-sized flowers of cobalt phosphide(i.e.,Co_2P) were synthesized via a solvothermal route with anhydrous ethanol(EtOH) and water(H_2O) as solvents and cetyl trimethyl ammonium bromide(CTAB) as a surfactant.The results show that the as-prepared Co_2P has an orthorhombic phase and consists of the massive well-crystallized flowers with some taper-shaped nanorods with the length of 1-1.5 μrn.The effects of the amount of CTAB,solvent ratio and reaction time on the formation of CO_2P flowers were also investigated.The Co_2P flowers can be formed at an appropriate amount of CTAB due to the production of free cetyltrimethylammonium(CTA^+) cations and the adsorption on some faces of Co_2P crystal.It is indicated that the as-prepared Co_2P flowers as a lithium battery cathode material exhibit the superior electrochemical property.The initial discharge capacity is468.4 mA·h/g,and the discharge capacity is 170 mAh/g after 100 cycles.