Preparation And Electrochemical Properties Of Go₃O₄/Graphene Composite

Environment pollution and combustion of fossil fuels are the issue we all faced today, so, the development of new energy storage is one of the solutions to solve the subject. And electrode material is the key to the energy storage has become one of hot research areas. Co₃O₄ has high specific capacity, but the poor conductive performance, good electrical conductivity graphene composite with Co₃O₄, can improve its performance. This paper mainly studied the preparation and electrochemical performance of the composite material Co₃O₄ and graphene, the main results were as follows:（1） Using homogeneous coprecipitation preparation of Co₃O₄ and graphene composites （Co₃O₄/rGO ）. In aqueous solution or graphite oxide （GO） dispersed in aqueous solution,we use CoCl2 as the source of cobalt, and CO（NH2）2 as the mineralizer, using the homogeneous coprecipitation preparation of graphene respectively are 7.7%, 13.5% and 25.2% composite materials (marked as Co₃O₄/rGO^-1,2,3).We use XRD, FT-IR and FE-SEM to test the morphology of all samples. The results show that the Co₃O₄ stacked on the lamellar structure of rGO is acicular structure. With the doping quantity increase of rGO, Co₃O₄/rGO microstructure of the composite material is slightly different.（2） Study of Co₃O₄/rGO composite as anode materials for lithium ion batteries electrochemical performance. The result shows that the initial discharge/charge capacity of Co₃O₄/rGO^-1,2,3 are 1359.0/824.9,1459.2/995.2 and 1786.6/1111.7mAhg^-1 at the current density of 0.1 Ag^-1 in the voltage of 0.005-3.0V. The discharge/charge capacity were higher than the pure Co₃O₄ (1205.0/687.7 mAhg^-1). Comparison of relatively high capacity of Co₃O₄/rGO-2, its first irreversible specific capacity is 464.0 mAhg^-1, the coulomb efficiency of 68.2%; Cycle performance tests show that except for the 1 st cycle （68.2%） is slightly low, Co₃O₄/rGO-2 retains good coulomb efficiency more than 94% at every cycle, which show its good circulatory; The result of rate performance tests show that when the current density increased to 2.0 from 0.1Ag^-1, the discharge specific capacity(1416.2mAhg^-1) of Co₃O₄/rGO-2 is reduced, but after the large current discharge, back to the small current, the discharge specific capacity (1261.5 mAhg^-1) of the material is close to the initial value, which intend the good performance.（3） We do a study about Co₃O₄/rGO composite to be used as electrode material for supercapacitors. Cyclic voltammograms show that the specific capacity of Co₃O₄/rGO^-1,2,3 are 241.5 Fg^-1、644.8Fg^-1 and 340.6Fg^-1, at a scan rate of 2 mVs^-1. The specific capacity of Co₃O₄/rGO composite is much bigger than that of pure Co₃O₄ (190.3 Fg^-1).