One embodiment is an EDLC with a capacitor cell that includes two electrodes of opposite polarity aligned in parallel, and a peptide separator disposed between the electrodes. The separator may be a peptide coating on an electrode surface. Another embodiment is an electrode for an electrochemical energy storage device, such as an EDLC, the electrode including graphene and coated with peptide. The peptide may act as a separator for the EDLC. A further embodiment is an electrode for an electrochemical energy storage device, the electrode-unit including: two graphene layers, CNTs, and electrolyte. The graphene layers are arranged separated along a first axis and aligned with parallel surfaces, where at least one graphene layer is coated with peptide. The CNTs are arranged along a second axis orthogonal to the first axis and disposed between the graphene layers. The electrolyte is impregnated within the volume defined between the graphene layers and CNTs.