Synthesis And Electrochemical Properties Of Nanostructure Metal Chalcogenides As Electrode Materials For The Supercapacitors

Faraday pseudocapacitance (also known as the pseudo-capacitor), a kind of supercapacitors, can provide even dozens times of the specific capacitance than electric double layer capacitors. Pseudo-capacitor can effectively overcome the low energy density weakness of the traditional capacitors and hold promise to replace the battery as the main new generation energy storage device. Electrode materials are the most important factor in determining the properties of pseudocapacitors. Now various compounds of transition metals are mainly used as the electrode materials for the pseudo-capacitors. There are two main methods to improve the specific capacitance of the electrode materials. One is to improve the inherent defects of poor conductivity of electrode materials, such as compositing the electrode materials with good conductive graphene, etc, or synthesising the material by using conductive materials such as nickel foam or carbon fiber cloth as the substrates. The other way is to synthesize nanostructure electrode materials with various structures and morphologies such as nanowires, nanorods, nanotubes, nanospheres, etc, which can effectively improve the capacitance performance of the electrode materials by increasing the specific surface area and the reaction active sites in contact with the electrolyte. The research on the above two methods has always been a very strong interest of researchers. Based on the above two methods, this paper mainly made the following research.1. In-situ synthesis and electrochemistry properties of free-standing bundle-like Coo.ssSe nanotube arrays on Ni form.A novel bundle-like Co0.85Se nanotube arrays on Ni form has been successfully synthesized through a hydrothermal method. The diameter and length of the single Co0.85Se nanotube were about 100 nm and 1?m, respectively. The electrochemical supercapacitor measurements were performed in a three-electrode system with the Co0.85Se nanotube arrays loaded Ni foam directly acted as the working electrode. The specific capacitance was as high as 1394 F g-1 at a current density of 4 A g-1, with the corresponding energy density and power density were 34.97 Wh kg-1 and 849.98 W kg-1, respectively. In addition, this Co0.85Se nanotube arrays electrode also exhibited good rate capability and cycle stability, suggesting its potential for high-performance supercapacitor application.2. Preparation and electrochemistry properties of flower-like NiSe nanomaterial for supercapacitors.A novel flower-like NiSe nanomaterial has been synthesized through a facile two-step hydrothermal method. This flower-like nanostructure NiSe exhibited good electrochemical performance when it was used as electrode material for supercapacitor. The specific capacitance of NiSe nanomaterials reached 956 F g'1 at 1 A g'1 and 514 F g"1 at 10 A g'1, together with good rate capability and cycle stability, suggesting its potential for high-performance supercapacitor application.3. Synthesis and electrochemistry properties of the flower-like NiS nanospheres as electrode materials for supercapacitors.Flower-like NiS nanospheres have been successfully synthesized through a facile two-step hydrothermal method. The specific capacitance of the flower-like NiS nanospheres reached 670.8 F g-1 at 2 A g-1 and 410.6 F g-1 at 5 A g-1. In addition, this flower-like NiS nanospheres also demonstrated excellent long time cycling stability with only 16.1% capacity losses after 1000 cycles at the current density of 5 A g-1, suggesting its potential for high-performance supercapacitor application.