混合氨-碱沉淀剂制备Ni（OH）2/还原氧化石墨烯复合材料及其电化学性能
Ammonia-alkali mixed precipitant route for preparation of Ni(OH)2/reduced graphene oxide composites and electrochemical performance

利用简单易行的化学沉淀-回流法制备了Ni（OH）2/还原氧化石墨烯（RGO）复合材料，研究了不同混合氨-碱沉淀剂对复合材料电化学性能的影响。采用XRD、拉曼光谱（Raman）和SEM表征Ni（OH）2/RGO复合材料的微观结构和形貌。当以NH3·H2O-NaOH作为沉淀剂时，Ni（OH）2/RGO复合材料中β-Ni（OH）2纳米片均匀分散在石墨烯片层之间，形成相互插层结构。利用循环伏安（CV）、恒电流充放电（GCD）和电化学交流阻抗（EIS）测试了复合电极材料的电化学性能。研究结果表明：放电倍率为0.2 C时，Ni（OH）2/RGO复合电极材料的放电比容量达到344.8 mAh/g，比β-Ni（OH）2的放电比容量高出约29%；5 C时放电比容量为274.5 mAh/g，经过50个循环，容量保持率为98.8%，呈现出良好的倍率性能和循环性能。 Nickel hydroxide/reduced graphene oxide (Ni(OH)2/RGO) composites were synthesized by simple and practicable chemical precipitation-reflux method. The influence of different ammonia-alkali mixed precipitant on electrochemical performance of composite materials was researched. The microstructure and morphology of the Ni(OH)2/RGO composites were characterized by XRD, Raman spectra and SEM. The synthesized Ni(OH)2/RGO composite shows that β-Ni(OH)2 nano sheets are homogeneously dispersed and inserted into RGO sheets, thus mutually inserted structure is formed using ammonium hydroxide-sodium hydroxide as precipitant. The electrochemical characteristics of composite electrode materials were tested by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results show that the prepared Ni(OH)2/RGO composite exhibits a high discharge specific capacity of 344.8 mAh/g at 0.2 C rate, and is 29% higher than the specific capacity of β-Ni(OH)2. The discharge specific capacity of the β-Ni(OH)2/RGO composite is 274.5 mAh/g at 5 C rate. Moreover, 98.8% of the initial specific capacity of the composite is maintained after 50 cycle test. Ni(OH)2/RGO composite displays a better rate capability and cycle performance as electrode material. 内蒙古青年科技英才计划（NJYT-14-A08）；内蒙古自然科学基金（2014MS0523；2015MS0208）；包头市科技计划（2015C2004-1）