Rational design and synthesis of hydrotalcite-like α-Co(OH)2 nanoflakes for extrinsic pseudocapacitive electrodes with superb cycling stability

Abstract Cycling stability and specific capacitance are two of important performance parameters for pseudocapacitive electrodes under frequent charging and discharging. Herein, we present a facile solvothermal approach to rationally design and fabricate chiffon-like and hydrotalcite-like α-Co(OH)2 nanoflakes for extrinsic pseudocapacitive electrode, which exhibits linear galvanostatic discharge behavior and superior charge-storage performance, including high capacitance of 475 F g−1 at 1 A g−1, excellent rate capability and superb cycling stability with capacitance retention of 93.9% after 10000 cycles at 10 A g−1. The superior performance is mostly attributed to the good electrical conductivity and stable microstructure of the hydrotalcite-like α-Co(OH)2 nanoflakes and the abundant redox active sites on the chiffon-like nanoflakes with short and facile electron transport. In addition, other α-Co(OH)2 samples with different morphologies and size as contrast are prepared and discussed, indicating that the morphology/size design and optimization of the α-Co(OH)2 could greatly improve the electrochemical energy-storage performance. The findings demonstrate that the chiffon-like and hydrotalcite-like α-Co(OH)2 nanoflakes have a great practical application potential in long-life and high-performance supercapacitors. This study also presents a facile way to design and prepare nanoflake-like materials with adjustable lateral size and thickness from spherical morphology consisting of nanoflakes.