循环伏安沉积纳米氧化钌基超级电容器电极材料

Supercapacitor Electrode Materials of Nanostructured Hydrous Ruthenium Oxide Deposited by Cyclic Voltammetry Method

摘要:

在三氯化钌 (RuCl3) 水溶液中，采用循环伏安法在钽电极表面电化学沉积无定形水合氧化钌(RuO2·xH2O) 作为超级电容器电极材料。能谱分析表明，在循环伏安负向扫描时Ru3+在钽电极表面还原为钌金属 (Ru)，沉积的Ru在随后的正向扫描时被氧化为RuO2·xH2O。扫描电镜观测显示出负向扫描沉积的Ru为纳米尺度，因而获得了纳米结构的RuO2·xH2O。由于纳米结构可以提高电极比表面积和显著缩短离子和电子的传输路径，因而获得了具有高电化学活性的RuO2基超级电容器电极材料。循环伏安、恒电流充放电和电化学阻抗谱测试证实，该电极材料在38% (质量分数, 下同)的H2SO4溶液中具有接近理想电容器的容量行为，比容量高达730 F·g-1 (扫描速率为50 mV·s-1)。在质量负载为1.2 mg·cm-2时，比容量仍高达700 F·g-1。另外，其容量在10万次循环后仍保持不变，充放电效率接近100%。并且该方法可以直接在钽金属基底上电化学沉积RuO2·xH2O，避免了在常规电化学沉积法中需要的预涂层

Abstract:

Nanostructured hydrous ruthenium oxide (RuO2·xH2O) was directly deposited on tantalum (Ta) substrates by cyclic voltammetry (CV) technology in RuCl3·xH2O aqueous solutions. The growth mechanism, revealed by energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) techniques, is that Ru3+ ions are reduced to nanostructured ruthenium (Ru) particles during negative potential scanning, then are oxidized to RuO2·xH2O granules (also in nanometers) during the following positive scanning. The unique nanometer structure of RuO2·xH2O, rather than the conventional “mud-cracked” structure, enable itself a high specific capacitance of 730 F·g-1 at a scanning rate of 50 mV·s-1 and a very fast charging/discharging ability. The speci?c capacitance is still up to 700 F·g-1 when the oxide loading is up to 1.2 mg·cm?2. In addition, the capacitance retains about 100% after 100,000 charging/discharging cycles. All of these indicate that the nanosized RuO2·xH2O is an excellent electrode material for energy storage and conversion devices, such as supercapacitors