Rakhi R B, Chen Wei, Hedhili M N, Cha Dongkyu, Alshareef H N
Material Science and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
ACS Appl Mater Interfaces. 2014 Mar 26;6(6):4196-206. doi: 10.1021/am405849n. Epub 2014 Mar 10.
Mesoporous cobalt oxide (Co3O4) nanosheet electrode arrays are directly grown over flexible carbon paper substrates using an economical and scalable two-step process for supercapacitor applications. The interconnected nanosheet arrays form a three-dimensional network with exceptional supercapacitor performance in standard two electrode configuration. Dramatic improvement in the rate capacity of the Co3O4 nanosheets is achieved by electrodeposition of nanocrystalline, hydrous RuO2 nanoparticles dispersed on the Co3O4 nanosheets. An optimum RuO2 electrodeposition time is found to result in the best supercapacitor performance, where the controlled morphology of the electrode provides a balance between good conductivity and efficient electrolyte access to the RuO2 nanoparticles. An excellent specific capacitance of 905 F/g at 1 A/g is obtained, and a nearly constant rate performance of 78% is achieved at current density ranging from 1 to 40 A/g. The sample could retain more than 96% of its maximum capacitance even after 5000 continuous charge-discharge cycles at a constant high current density of 10 A/g. Thicker RuO2 coating, while maintaining good conductivity, results in agglomeration, decreasing electrolyte access to active material and hence the capacitive performance.
采用一种经济且可扩展的两步法，在柔性碳纸基底上直接生长介孔氧化钴（Co3O4）纳米片电极阵列，用于超级电容器应用。相互连接的纳米片阵列形成三维网络，在标准两电极配置下具有卓越的超级电容器性能。通过在Co3O4纳米片上电沉积分散的纳米晶水合RuO2纳米颗粒，Co3O4纳米片的倍率性能得到显著改善。发现最佳的RuO2电沉积时间可带来最佳的超级电容器性能，此时电极的可控形态在良好的导电性和电解质对RuO2纳米颗粒的有效接触之间实现了平衡。在1 A/g电流密度下获得了905 F/g的优异比电容，在1至40 A/g的电流密度范围内实现了近78%的恒定倍率性能。即使在10 A/g的恒定高电流密度下连续进行5000次充放电循环后，该样品仍能保持其最大电容的96%以上。较厚的RuO2涂层在保持良好导电性的同时，会导致团聚，减少电解质对活性材料的接触，从而降低电容性能。
