We request 2 days beam time on HRPD for ex-situ, room temperature, powder diffraction studies of P2-type sodium-ion battery cathode materials based on the Na2/3Mn2/3Ni1/3O2 standard material. The principal objective of this proposal is to determine the structure of a series of P2-type materials, to whit: Na2/3Mn2/3Ni1/3O2, Na0.656Mn0.7Ni0.3O2 and Na0.62Mn0.75Ni0.25O2, which have each been synthesised at four different temperatures. HRPD is the beamline of choice because of its excellent resolution, which is necessary for elucidating the exact structural variation between the materials. The knowledge gained will be used to inform the synthesis of improved sodium-ion battery cathode materials.