A kind of surface-modified graphene with oxygen-containing functional groups for supercapacitors
A supercapacitor, surface modification technology, applied in graphene, hybrid capacitor electrodes, chemical instruments and methods, etc., can solve the problems of reducing graphene charge storage capacity, reducing graphene active sites, reducing the application efficiency of active sites, etc. , to achieve the effect of improving the ability of the affinity electrolyte, the reduction method is simple, and the performance of the supercapacitor is improved
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Embodiment 1
[0030] a) 3g of graphite and 1.5g of NaNO 3 Add 70ml of concentrated sulfuric acid under ice bath conditions, stir well and add 9g of KMnO 4 , ice bath for 12h; then the temperature was raised to 35°C and kept for 24h; then deionized water was added, the temperature was raised to 98°C and stirred for 12h. After the reaction is completed, add 20ml of H with a mass ratio of 30% 2 O 2 , then diluted with dilute hydrochloric acid, suction filtered into a filter cake, centrifugally cleaned, and ultrasonically treated to obtain graphene oxide with a high degree of oxidation.
[0031] The graphene oxide prepared in the above steps is fully dispersed in deionized water, hydrothermally treated at a temperature of 200° C., washed with water suction filtration, and freeze-dried to obtain graphene with surface-modified oxygen-containing functional groups. The mutual repulsion of oxygen-containing functional groups on the surface of graphene prevents graphitization and agglomeration bet...
Embodiment 2
[0034] The graphene oxide prepared by the steps described in Example 1 was fully dispersed in deionized water, hydrothermally treated at a temperature of 180° C., washed with water by suction filtration, and freeze-dried to obtain graphene with surface-modified oxygen-containing functional groups.
[0035] The surface-modified graphene with oxygen-containing functional groups has a specific capacity of 321 F / g at a specific current of 1 A / g, and the specific current is increased by 50 times and retains 71% of the specific capacity; at a scan rate of 3 mV / s, the specific capacity is 320 F / g g, 77% of the specific capacity is retained when the scan rate is increased by a factor of 50; the specific capacity can still retain 95% of the initial capacity after 10,000 charge-discharge cycles.
Embodiment 3
[0037] The graphene oxide prepared by the steps described in Example 1 was fully dispersed in deionized water, hydrothermally treated at a temperature of 140° C., washed with water by suction filtration, and freeze-dried to obtain graphene with surface-modified oxygen-containing functional groups.
[0038] The surface-modified graphene with oxygen-containing functional groups has a specific capacity of 330 F / g at a specific current of 1 A / g, and the specific current is increased by 50 times and retains 67% of the specific capacity; the specific capacity at a scan rate of 3 mV / s is 324 F / g. g, 50-fold increase in scan rate with 74% specific capacity retention.
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