Preparation and electrochemical properties of cobalt aluminum layered double hydroxide/carbon-based integrated composite electrode materials for supercapacitors

Abstract

Supercapacitors have been widely developed in electrochemical energy storage field. Cobalt aluminum layered double hydroxide (CoAl-LDH) has attracted much attention because of its potential characteristics in energy storage. However, this materials also have the disadvantages of poor electrical conductivity and short cycle life. In order to solve this problem, a special structure of CoAl-LDH/carbon-based composite integrated electrode materials are constructed by one-step hydrothermal method, and the electrochemical properties of the materials are improved by changing the solvent composition. It is found that the electrochemical properties of CoAl-LDH/graphitic carbon nitrides (g-C3N4), CoAl-LDH/carbon nanotube (CNT) and CoAl-LDH/activated carbon (AC) composites are superior to those of pure CoAl-LDH, and CoAl-LDH/AC, as a new type of lamellar structure electrode material, has the best capacitance performance. Compared with CoAl-LDH/AC prepared with pure water as the solvent, adding 5 mL ethanol to the solvent can increase the specific capacitance of CoAl-LDH/AC composites from 1700 F g−1 (850 C g−1) to 1891 F g−1 (946 C g−1) at 1 A g−1 current density. At 7 A g−1 high current density, after 5000 cycles, the capacitance retention rate is increased from 40.6% to 66.3%. These electrochemical properties suggest that CoAl-LDH/AC composites can be one of the high performance electrodes for supercapacitors.Hydrothermal method; CoAl-LDH/carbon-based composite integrated electrode materials; Solvent composition; Specific capacitance; Electrochemical performance.