▎ 摘　　要

Co(CO3)(0.5)(OH)center dot 0.11H(2)O/graphene composites are synthesized by a hydrothermal method through altering reaction time. Their capacitive performance is studied. The results show the that the crystallite size of Co(CO3)(0.5)(OH)center dot 0.11H(2)O in the composites increases when reaction time prolongs. The morphology of Co(CO3)(0.5)(OH)center dot 0.11H(2)O in the composites consists of flake and rod structures and remains unchanged when reaction time prolongs. The specific capacitance of the composites decreases when the composites prepared in long reaction time. Co(CO3)(0.5)(OH)center dot 0.11H(2)O/GNS-8 (Co(CO3)(0.5)(OH)center dot 0.11H(2)O/graphene composites prepared for 8 h) electrode possesses the largest specific capacitance. A specific capacitance of 197.4 F g(-1) is obtained at 0.2 A g(-1) in Co(CO3)(0.5)(OH)center dot 0.11H(2)O/GNS-8 electrode and its specific capacitance reduces to 136.2 F g(-1) at 1.8 A g(-1). 69% of the specific capacitance is remained. The specific capacitance after 2400 cycles reaches 364.5 F g(-1) at 0.2 A g(-1), which is 184.7% of initial specific capacitance.