Electric vehicles are poised to play a large role in the decarbonisation of the transportation sector. World governments have pledged to bring 13 million plug-in electric vehicles on the road by 2020 and 100 million by 2030. The rapid expansion required to meet these targets, from a global stock of 5 million electric vehicles in 2018, has the potential to be constrained by material supply chains. This study has identified 7 key elements which are significant supply risks to the electric vehicle industry: battery grade natural graphite, lithium and cobalt for electric vehicle batteries, and the rare earth elements dysprosium, terbium, praseodymium and neodymium for electric vehicle motors. None of these elements are able to be substituted without (i) increasing the supply risk of the other constrained elements, or (ii) altering industry wide manufacturing processes. The inability to fully mitigate material supply risks at the required market expansion rates is a key issue for minimising carbon emissions from the transportation sector.