Preparation and electrochemical performance of the layered cobalt oxide (Co 3 O 4 ) as supercapacitor electrode material
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ORIGINAL PAPER
Preparation and electrochemical performance of the layered cobalt oxide (Co3O4) as supercapacitor electrode material Lijing Xie & Kaixi Li & Guohua Sun & Zhongai Hu & Chunxiang Lv & Jianlong Wang & Changming Zhang
Received: 11 July 2012 / Revised: 15 August 2012 / Accepted: 26 August 2012 # Springer-Verlag 2012
Abstract Layered Co 3 O 4 composed of oriented selfassembled micrometer-length rectangular 2D flakes has been successfully synthesized by a hydrothermal method in combination with subsequent calcination process. Structural and morphological characterizations were performed using powder X-ray diffraction and field emission scanning electron microscopy. The component and thermal stability of the sample were measured by FT-IR and thermal analyses, including thermogravimetry and differential thermal analysis. The electrochemical performances of the as-prepared Co3O4 product were investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and constant current charge/discharge techniques. The electrochemical results demonstrate that the layered Co3O4 product displays good capacitive behavior with a specific capacitance of 263 Fg−1 within a potential range of −0.4–0.55 V at a current density of 1 Ag−1 and a large capacity retention with 89.4 % of the initial capacitance over 1,000 consecutive cycles at 3 Ag−1, indicating that the asprepared Co3O4 product can be a promising electroactive material for supercapacitor. Keywords Co3O4 . Polyvinyl pyrrolidone . Hydrothermal method . Supercapacitor L. Xie : K. Li (*) : G. Sun : C. Lv : J. Wang : C. Zhang Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, People’s Republic of China e-mail: [email protected] L. Xie : C. Zhang Graduate University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China Z. Hu Gansu Key Laboratory of Polymer Materials, Northwest Normal University, Lanzhou 730070( Gansu, People’s Republic of China
Introduction Supercapacitors (electrochemical capacitors) have high power density, high durability, long cycle life, flexible operating temperature, environmental friendliness, and safety [1–5]. These beneficial properties have made supercapacitors very popular in many applications, such as electric vehicles, electric hybrid vehicles, digital communication devices, digital cameras, mobile phones, electric tools, pulse laser techniques, uninterruptible power supplies as well as energy storage generated by solar cells [6–9]. Pseudocapacitors [3], whose capacitance is attributed to the continuous and reversible Faradic redox reaction of electrode materials, are one kind of supercapacitor. Hydrous ruthenium oxide has been shown to exhibit ideal pseudocapacitive behavior [10] and has a specific capacitance higher than 800 Fg−1 [11, 12]. However, the high cost of Ru has retarded its commercial acceptance as electrode material in electrochemical capacitors. This limitation has encouraged finding other cheaper materials with capacitive behavior
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