We intend to utilise the unique ability of neutron reflection to probe surface structures of ions at a graphene substrate with particular relevance to electrolyte solutions and electrochemical double layer capacitors (supercapacitors). Here we aim to directly assess one of the key factors determining the capacitance of an electrode/electrolyte interface -the distance between the electrode surface and the centres of the bound ions perpendicular to the surface. This approach can also be used to address the solvation of the ions at the surface.