Mesoscopic architectures of Co(OH)2 spheres with an extended array of microporous threads as pseudocapacitor electrode materials

• Co(OH)2 microporous nano strands are synthesized.
• The surface area of these nano strands was found to be ∼100 m2 g−1.
• These nano strands reveal a significant power density of 8.2 kW kg−1.

The present study demonstrates a low temperature hydrothermal route for the synthesis of α-cobalt hydroxide comprising of randomly arrayed nano strands in a three dimensional plane. These micro/nano hybrid structures were used as building blocks for processing high surface area supercapacitor electrodes. Surface area of these structures was measured to be ∼100 m2 g−1. The influence of surface morphology in three different electrolytes namely lithium hydroxide, sodium hydroxide and potassium hydroxide was analyzed. The influence of surface morphology on capacitance and internal resistance was also determined and explained on the basis of redox reactions in these electrolytes. Capacitance values as high as 1024 F g−1 was attained for these structures when employed as thin film electrodes with life extending to more than 5000 cycles. Inductively coupled plasma-atomic emission spectroscopy was used to determine the electrode dissolution in the given electrolyte and the observations were co-related with the cycling stability. Low self-discharge, high rate capability along with low cost makes them promising systems for supercapacitor applications.

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