People are excited about batteries, from electric cars to Tesla’s 129 megawatt-hour energy storage project in South Australia. But one important issue is often overlooked: the raw materials needed to build this technology – where they come from and their environmental cost... We need to think carefully about the security of the sources of lithium-ion battery materials, as well as the environmental impact of their extraction... [One] main environmental concern [...] is that the extraction can impact water supply in desert areas. It also uses some chemicals for purification... Turning minerals into batteries takes a supply chain, and each stage – mining, processing, refining, manufacturing – could present a bottleneck. Manufacturers such as electric vehicle makers should be concerned that the supply of one of the key mineral components, or the processing and refining infrastructure, could become too centralised in a single country...