Hierarchical materials Electrodes

Hierarchically Nanostructured Electrode Materials for Lithium-Ion Batteries... 

Carbon nanostructures often serve as components in hierarchically structured electrode materials. Conductive carbon, for example, is densely packed, sp -bonded, and classified based on its dimensions. A major asset of nanostmctured carbon is its high relative surface area, which facditates an increase of both MET and DET. 

The proper design and organization of hierarchically structured electrodes optimize the bioelectronic performance and enhance mass transport of fuel to the biocatalysts. By using nanostructured materials at the interface, the relative surface area for catalyst loading is increased compared with bulk materials and the distance between catalyst and the conductive surface may be decreased to enhance DET. Nanostructured modification or functionalization of 2D surfaces may enhance power output however, the essentially planar surface can limit scalability. 

Conducting polymers can be mixed with or electrochemically deposited onto transition metal oxides to achieve better performances as electrode materials. However, the wrapping of conducting polymers on metal oxides may reduce the effective contact area between metal oxides and electrolytes. This will further impede insertion of alkali ions into metal oxides and result in poor rate performance with low specific capacitance. A rational strategy is to use conducting polymers as active electrode materials directly and optimize their structures. To this end, a hierarchically nanostructured conductive polymer hydrogel was synthesized by a facile interfacial polymerization (Shi et al., 2014). 

Estevez, L., R. Dua, N. Bhandari, A. Ramanujapuram, R Wang, and E. R Giannelis. 2013. A facile approach for the synthesis of monolithic hierarchical porous carbons— High performance materials for amine based CO2 capture and supercapacitor electrode. Energy Environmental Science 6 1785-1790. 

Wang, Q., J. Yan, Y. B. Wang et al. 2014. Three-dimensional flower-like and hierarchical porous carbon materials as high-rate performance electrodes for supercapacitors. Carbon 67 119-127. 

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