The drive to replace polluting petrol and diesel cars with a new breed of electric vehicles has gathered momentum in recent weeks. But there is an unanswered environmental question at the heart of the electric car movement: what on earth to do with their half-tonne lithium-ion batteries when they wear out? [...] In the EU as few as 5% of lithium-ion batteries are recycled... Not only do the batteries carry a risk of giving off toxic gases if damaged, but core ingredients such as lithium and cobalt are finite and extraction can lead to water pollution and depletion among other environmental consequences. There are, however, grounds for optimism... “Car producers will be accountable for the collection and recycling of spent lithium-ion batteries,” he [chief executive of Umicore] says. “Given their sheer size, batteries cannot be stored at home and landfilling is not an option.”