We present a study to understand the role of defects in enhancing the charge capacity of many layered graphene by gradually increasing the defect concentration in a pristine graphene sample by ion beam irradiation. An Ar+ ion beam with energies of 50-105 KeV was used to engineer defects by varying the penetration depth of the ion beam in the sample. Electrochemical cycling of these defective graphenic layers against Li metal foil showed a correlation between the specific charge capacity and the energy of the irradiated ion beam used to create defects. The charge capacity was found to increase to 440mAh/g compared to the charge capacity of a pristine many layered graphene sample of 250mAh/g after 100 cycles. The charge capacity however, doesn't increase linearly with the energy of the Ar+ ion beam but tends to decrease after an optimum value that can be attributed to the distribution of the created defects in the sample.