How batteries are powering ahead

Tesla's Elon Musk plans to make some big announcements about batteries that could transform cars, electricity and the fight against climate change. Justin Rowlatt gets the inside scoop from Seth Weinbaum, journalist at the electric vehicles news-site Electrek. Meanwhile, battery chemist Paul Shearing of University College London explains how lithium-ion batteries made the smartphone possible, and are now set to revolutionise transport. But electrifying the world's one billion road vehicles is no small task, not to mention building even bigger batteries to stabilise renewable energy sources on our electricity grids. Where on earth will all the lithium come from? Justin speaks to another American tech entrepreneur who thinks he has the answer - Teague Egan of start-up EnergyX. Producer: Laurence Knight (Picture: Battery charging icons; Credit: Iuliia Kanivets/Getty Images)