Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors
Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors
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DOI：
10.1038/nnano.2011.13
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发表时间：
2011-04-01
影响因子：
38.3
通讯作者：
Chen, Mingwei
中科院分区：
文献类型：
--
作者：
Lang, Xingyou;Hirata, Akihiko;Chen, Mingwei
电化学超级电容器可以提供高水平的电力并提供长的工作寿命（1-8），但它们的储能密度对于许多重要的应用来说太低（2，3）。准电容过渡金属氧化物如MnO 2可用于制造此类超级电容器中的电极，因为它们被预测具有用于存储电荷的高电容，同时还便宜且对环境无害（9，10）。然而，MnO 2的导电性差（10（-5）-10（-6）S cm（-1））限制了高功率应用的充电/放电速率（10，11）。在这里，我们表明，由纳米多孔金和纳米晶MnO 2制成的混合结构具有增强的导电性，导致组分MnO 2的比电容（类似于1，145 F g（-1））接近理论值（9）。纳米多孔金允许电子通过MnO 2传输，并促进MnO 2和电解质之间的快速离子扩散，同时还充当双层电容器。这种混合结构提供的高比电容和充电/放电速率使它们成为超级电容器中电极的有前途的候选者，将高能量存储密度与高水平的功率输送相结合。
Electrochemical supercapacitors can deliver high levels of electrical power and offer long operating lifetimes(1-8), but their energy storage density is too low for many important applications(2,3). Pseudocapacitive transition-metal oxides such as MnO2 could be used to make electrodes in such supercapacitors, because they are predicted to have a high capacitance for storing electrical charge while also being inexpensive and not harmful to the environment(9,10). However, the poor conductivity of MnO2 (10(-5)-10(-6) S cm(-1)) limits the charge/discharge rate for high-power applications(10,11). Here, we show that hybrid structures made of nanoporous gold and nanocrystalline MnO2 have enhanced conductivity, resulting in a specific capacitance of the constituent MnO2 (similar to 1,145 F g(-1)) that is close to the theoretical value(9). The nanoporous gold allows electron transport through the MnO2, and facilitates fast ion diffusion between the MnO2 and the electrolytes while also acting as a double-layer capacitor. The high specific capacitances and charge/discharge rates offered by such hybrid structures make them promising candidates as electrodes in supercapacitors, combining high-energy storage densities with high levels of power delivery.