▎ 摘　　要

Sulfonated graphene (GP-SO3H) was prepared by grafting reaction of sulfonated diazoniun salt. The sulfonated graphene was characterized by Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy(SEM), respectively. The experimental results indicate that the sulfonic groups have been grafted onto graphene oxide. The sulfonated graphene/activated carbon composite electrode (GP-SO3 H/AC) was prepared by mixing 10% (mass fraction) GP-SO3H as dopant. Compared with AC electrode, this composite electrode exhibits an ideal double layer capacitive behavior and high conductivity, confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. The hybrid capacitor was assembled by the resultant GP-SO3 H/AC as negative electrode and AC as counter electrode for capacitor deionization (CDI). Under the constant current charging-discharging condition, the salt removal amount of 10. 87 mg/g in single cycle was obtained, about 2. 4 times that of the normal AC capacitor. And the current efficiency was improved dramatically owing to the facile adsorption of sulfonic groups to cations, and the shielding effect of sulfonic groups on the counter-ions. The asymmetric capacitor is expected to be used for actual application in brackish water desalination.