Preparation of the Novel Nanocomposite Co(OH)₂/ Ultra‐Stable Y Zeolite and Its Application as a Supercapacitor with High Energy Density

A Co(OH)2/zeolite nanocomposite with an extraordinarily high specific capacitance is described. Nanometer-sized Co(OH)2 whiskers on the zeolite surface permit high electrochemical accessibility and a fast diffusion rate of electrolyte through the material, resulting in a specific capacitance approaching the theoretical limit. Increasing the Co(OH)2 loading increases whisker growth (see Figure), until bulk Co(OH)2 begins to nucleate and grow in solution (arrows).