表面活性剂软模板制备石墨烯/镍-铝层状双氢氧化物复合材料及其超级电容性能

Synthesis of Graphene /Nickel-Aluminium Layered Double-Hydroxide Composites Using Surfactant as a Soft Template and Its Supercapacitor Performance

氧化石墨经过微波辐射和高温热裂解处理得到深度还原的石墨烯。超声分散石墨烯于去离子水形成稳定的石墨烯分散液,加入硝酸镍、硝酸铝、尿素和表面活性剂软模板剂Pluronic 123;采用水热法制备石墨烯/镍铝层状双金属氢氧化物复合材料;利用扫描电镜、透射电镜、X-射线衍射和红外光谱对此复合材料进行结构和形貌表征。结果表明表面活性剂的空间限制及调节作用,使之形成超薄的镍铝层状双金属氢氧化物纳米片,且均匀分散在褶皱的石墨烯纳米片上。研究了复合材料作为超级电容器电极的电化学性能。结果表明,复合材料电极的表观多相电子转移常数(k s)为0.727 s-1,明显高于单独的镍铝双金属氢氧化物,因此石墨烯的引入大大改善了材料的电子传导性。在1 A/g的电流密度下,复合材料电极的比电容为1 354.8 F/g。当电流密度增加到10A/g时,循环充-放电1 000次后,比电容仍保持在98.5%以上。在4 kW/kg的功率密度下,其能量密度达到12.96 Wh/kg。所制备的石墨烯/镍铝层状双金属氢氧化物复合材料提供了高的比电容、充-放电循环稳定性和能量密度。

A well-reduced graphene was made from graphite oxide using microwave irradiation and thermal annealing treatments. The graphene was subsequently dispersed in deionized water to form a stable graphene dispersion in the help of ultrasonic wave. Then,nickel nitrate,aluminum nitrate,urea and surfactant Pluronic 123 as the soft template agent were added into the dispersion,using hydrothermal synthesis method to prepare graphene/nickel-aluminium layered double-hydroxide composite. The scanning electron microscope,transmission electron microscope,X-ray diffraction and IR spectrum were used to investigate the structure and morphology characterization of the composite. The space constraint and regulation of the surfactant result in forming ultrathin nickel-aluminium layered double -hydroxide nanoflakes,which were well dispersed on the surface of wrinkled graphene nanosheets. Moreover,electrochemical performance of the composite was studied as supercapacitor electrode materials. The results indicate that apparent heterogeneous electron transfer rate constant （ks） was found to be 0. 727 s-1 ,which is obviously higher than that of pure nickel-aluminium layered double-hydroxide. This has demonstrated that the introduction of graphene improves the electronic conductance. At current density of 1 A/g,the composite provides a maximum specific capacitance of 1 354.8 F/g. The value was above 98.5% of capacitance retention after 1 000 cycles when the current density increased up to 10 A/g. The power density of 12.96 Wh/kg was obtained when the energy density is 4 kW/kg. Therefore,the as-prepared graphene/nickel-aluminium layered double-hydroxide composte is of high specific capacitance,good cycle stability and power density.